{"Bibliographic":{"Title":"The Navarin Basin environment and possible consequences of planned offshore oil and gas development /","Authors":"","Publication date":"1984","Publisher":""},"Administrative":{"Date created":"08-20-2023","Language":"English","Rights":"CC 0","Size":"0000426901"},"Pages":["The Navarin Basin Environment of\nTD\n195\n.P4\nPossible Consequences\nN3\nned and Offshore Oil and Gas Development\n1984\nOuter Continental Shelf Environmental Assessment Program\nJuneau, Alaska\nDEPARTMENT OF COMMERCE\nof\nU.S. National Oceanic and Atmospheric Administration\nU.S. DEPARTMENT OF THE INTERIOR\nMinerals Management Service\nNational Ocean Service\nOffice of Oceanography and Marine Services\nOcean Assessments Division","TD\n195\nP4\nN3\n1984\nThe Navarin Basin Environment\nand Possible Consequences of\nPlanned Offshore Oil and Gas Development\nEdited by\nLAURIE E. JARVELA\nOuter Continental Shelf Environmental Assessment Program\nJuneau, Alaska\nMAY 1984\nLIBRARY\nOCT 18 2005\nNational Oceanic &\nAtmospheric Administration\nU.S. Dept. of Commerce\nUNITED STATES\nUNITED STATES\nDEPARTMENT OF COMMERCE\nDEPARTMENT OF THE INTERIOR\nMalcolm Baldridge, Secretary\nWilliam P. Clark, Secretary\nNATIONAL OCEANIC AND\nMINERALS MANAGEMENT SERVICE\nATMOSPHERIC ADMINISTRATION\nWilliam D. Bettenberg, Director\nJohn V. Byrne, Administrator","","Notices\nThis report has been reviewed by the U.S. Department of Commerce, National Oceanic\nand Atmospheric Administration's Outer Continental Shelf Environmental Assessment Program\noffice, and approved for publication. The interpretation of data and opinions expressed in\nthis document are those of the authors and synthesis meeting participants. Approval does\nnot necessarily signify that the contents reflect the views and policies of the Department of\nCommerce or those of the Department of the Interior.\nThe National Oceanic and Atmospheric Administration (NOAA) does not approve,\nrecommend, or endorse any proprietary product or proprietary material mentioned in this\npublication. No reference shall be made to NOAA or to this publication in any advertising\nor sales promotion which would indicate or imply that NOAA approves, recommends, or\nendorses any proprietary product or proprietary material mentioned herein, or which has\nas its purpose an intent to cause directly or indirectly the advertised product to be used or\npurchased because of this publication.\niii","","Preface\nOn 14 November 1974, the Bureau of Land Management (BLM), U.S. Department of the\nInterior, published a new accelerated leasing schedule proposing 21 Outer Continental Shelf\n(O€S) oil and gas lease sales. This schedule was in response to President Nixon's order to\naccelerate leasing largely by opening up \"frontier\" OCS areas in order to gain self sufficiency\nin meeting the nation's energy needs. The Alaskan continental shelf, comprising 74% of all\nU.S. continental shelf areas and extending as far as 960 km off the coast in the southeastern\nBering Sea, constitutes the nation's largest unexplored petroleum area. Consequently, Alaska\nhas received special prominence in the planning schedules for OCS oil and gas development.\nAs part of the Alaskan OCS leasing program the BLM initiated the Outer Continental Shelf\nEnvironmental Assessment Program (OCSEAP) in 1975 through an interagency Basic Agree-\nment with the National Oceanic and Atmospheric Administration (NOAA), U.S. Department\nof Commerce. OCSEAP is a comprehensive, multidisciplinary environmental studies program\nthat provides the BLM, and more recently the Minerals Management Service (MMS), and other\nagencies with environmental data and results of original research to help them formulate leasing\ndecisions and to develop management strategies to obviate or mitigate undesirable effects\non the marine environment and its living resources resulting from OCS oil and gas develop-\nment. OCSEAP results are also available to the public and interest groups, in the form of\nprogrammatic documents and through their participation in reviews of environmental infor-\nmation for specific OCS areas.\nThe Navarin Basin was first proposed for OCS oil and gas leasing in 1979. It is the most\nremote of all Alaskan planning areas, being located far offshore in the central Bering Sea.\nThe planning area encompasses about 15 million hectares; it is bounded to the north and\nsouth by the 63° and 58° N. parallels, respectively, to the west by the U.S.-U.S.S.R. 1867\nConvention Line and 180° W. meridian, and to the east by the 174° W. meridian. The Depart-\nment of the Interior held the first lease sale for the area (OCS Sale 83) in April 1984; another\n(Sale 107) is scheduled for March 1986.\nBecause of the Navarin Basin's remoteness, the regional environmental data base was\ncomparatively scanty when it was placed on the OCS leasing schedule. OCSEAP subsequently\ninitiated several research efforts to address perceived key information gaps. These included\na limited number of field investigations and a summarization of available environmental infor-\nmation. The compilation was conducted by Science Applications, Inc. (SAI) under contract\nto NOAA; it was submitted to OCSEAP in December 1981.\nIn late October 1982 OCSEAP convened a 3-day Navarin Basin Synthesis Meeting in\nAnchorage, Alaska. One major objective of the meeting was to update the document prepared\nby SAI. As a consequence of the field studies that were underway during and after the prepara-\ntion of the document, a significant amount of new data had become available in 1982. Another\nobjective was to assess selected issues related to possible oil and gas development in the basin;\nthese concerned marine mammals, marine birds, environmental hazards, and fishery resources.\nU","The meeting began with a plenary session in which the participants were presented over-\nviews on the MMS study program and development scenarios, industry perspectives. a.summary\nof a forerunner transport workshop (held in Santa Monica in September 1982). and oil spill\nclean-up technology. These overviews were intended to provide information and a context\nfor the following workshop sessions. Information presented at the synthesis meeting was used\nby the MMS in the preparation of the Sale 83 draft environmental impact statement, which\nwas released in June 1983.\nThis report is in large part the end product of the synthesis meeting. However. it also includes\na significant amount of pertinent information that postdates the meeting or is appropriate\nto make the report more cohesive and comprehensive. The reader will find that the depth\nand breadth of the subject matter presented vary considerably among chapters. To a certain\ndegree this reflects the quality and quantity of available information. However, it also reflects\neditorial discretion. We have attempted to emphasize those attributes of the Navarin Basin\nand its biota that are perceived to be most at issue within the context of the proposed oil\nand gas development activities. This is most evident in the newly created final chapter. Ob-\nviously, a number of other environmental questions and issues remain to be further evaluated\nand resolved.\nM. J. Hameedi\nProgram Manager, Outer Continental Shelf\nEnvironmental Assessment Program\nvi","Acknowledgments\nThis report is the result of the efforts and cooperation of individuals from a variety of\norganizations within and outside OCSEAP: included are representatives of several federal\nagencies, the State of Alaska, universities, the petroleum industry, and private consultants.\nThe original summary of available environmental knowledge of the Navarin Basin was\nprepared at SAI's Boulder, Colorado, office by Ken Fucik, Bob Peterson, Joe Strauch, Jr., and\nGeorge Tamm.\nThe following persons helped make the Navarin Basin Synthesis Meeting a success. Allan\nAllen, Jawed Hameedi, Jerry Imm, Hans Jahns, Mauri Pelto, and Fred Sieber gave presenta-\ntions during the plenary session. Workshops were chaired by Cleve Cowles, Herman Karl, Mauri\nPelto, Allan Springer, Fredrik Thorsteinson, and Tom Warren. Supporting them were rapporteurs\nGuy Oliver, Bill Sackinger, Lyman Thorsteinson, and Steve Zimmerman. Chuck Cortese, Sharon\nHillman, Mark Hutton, Gunnar Knapp, and Terry Sample gave presentations in the fisheries\nworkshop. Bruce Kirstein and David Liu were instrumental in developing the quantitative oil\nspill transport and dispersion scenarios used as a basis for impact assessments. Marilyn Allen,\nBill Hopkins (Alaska Oil and Gas Association), and Toni Johnson provided much appreciated\nassistance during the planning and conduct of the meeting. Thanks also go to the other par-\nticipants whose questions, comments, and insights made the deliberations more informative\nand fruitful. Meeting attendees are listed at the back of this report.\nMany persons contributed to the revision and updating of the draft report prepared by\nSAI. Tom Kozo, Mauri Pelto, Terry Sample, Fred Sieber, Allan Springer, Fredrik Thorsteinson,\nand Lyman Thorsteinson provided written contributions. Paul Carlson, George Hunt, Herman\nKarl, Carol-Ann Manen, Guy Oliver, and Art Sowls reviewed portions of the revised document,\nwhile the MMS Alaska OCS Office staff and Jawed Hameedi, OCSEAP, undertook the review\nof the entire report. Barbara Griffin of our office typed the numerous drafts of the chapters.\nCatherine Mecklenburg (Point Stephens Press) coordinated preparation of the book for printing\nand personally attended to the technical editing, book design, and typesetting. Susan Alexander\n(Gossamer Graphics) prepared the illustrations, including the cover art, and camera-ready copy.\nGene Walsh (GKW Graphics) updated many of the maps that originally appeared in the draft\nreport to include the revised boundary of the Navarin Basin planning unit.\neii","","Contents\nPage\nPreface\nV\nAcknowledgments\nvii\nList of Figures\nxi\nList of Tables\nXV\n1\nChapter 1.\nGeography and Physiography\n1.1\nGeography\n1\n3\n1.2\nPhysiography\n3\nChapter 2.\nGeology\n3\n2.1\nStructural Framework\n2.2\nSurficial Sediments\n4\n2.3\nSediment Movement\n11\n12\n2.4\nSeismicity and Faulting\n12\n2.5\nPetroleum Potential\nMeteorology, Sea Conditions, and Sea Ice\n17\nChapter 3.\n17\n3.1\nClimate\n17\n3.2\nWeather\n18\n3.3\nStorm Tracks\n18\n3.4\nSea Conditions\n18\n3.5\nSuperstructure Icing\n31\n3.6\nSea Ice Distribution\n34\n3.7\nMarginal Ice Zone\n41\nChapter 4.\nOceanography\n41\n4.1\nHydrographic Structure\n42\n4.2\nSummer Circulation\n45\n4.3\nWinter Circulation\n49\n4.4\nModel Results\n50\n4.5\nTides\n51\n4.6\nChemistry and Nutrients\n55\nChapter 5.\nLower\nTrophic Levels\n55\n5.1\nBacteria\n55\n5.2\nPhytoplankton\n56\n5.3\nZooplankton\n59\n5.4\nBenthos\n63\nChapter 6.\nFishery Resources\n64\n6.1\nIchthyofauna\n65\nCommercial Fisheries (Finfish)\n6.2\n68\nCommercial Fisheries (Shellfish)\n6.3\n73\nFactors Affecting Fishery Resources\n6.4\nIX","Page\n77\nChapter 7. Marine Birds\n77\nPelagic Distribution of Seabirds\n7.1\n82\n7.2\nBreeding Colonies\n87\n7.3\nWaterfowl\n88\nShorebirds and Terrestrial Birds\n7.4\n88\nStatus of Seabird Populations\n7.5\n91\nChapter 8. Marine Mammals\n92\n8.1 Cetaceans\n92\n8.1.1 Baleen Whales\n94\n8.1.2 Toothed Whales\n96\n8.1.3 Cetacean Prey and Abundance\n97\n8.2 Pinnipeds\n98\n8.2.1 Hair Seals\n100\n8.2.2 Walruses\n101\n8.2.3 Eared Seals\n102\n8.2.4 Pinniped Prey and Abundance\n103\nChapter 9. Oil and Gas Development and Related Issues\n9.1 Resource Projections and Exploration, Development.\n103\nand Production Assumptions\n103\n9.1.1 Resource Projections\n104\n9.1.2 Exploration and Production Scenarios\n106\nOil Spill Transport, Environmental Partitioning. and Fate\n9.2\n106\n9.2.1 Advection\n110\n9.2.2 Horizontal and Vertical Spreading\n114\n9.2.3 Partitioning and Fate\n119\nHazards to Development\n9.3\n119\n9.3.1 Geologic Hazards\n120\n9.3.2 Ice Hazards\n121\n9.3.3 Wind and Wave Hazards\n121\n9.4 Impacts on Fisheries\n122\n9.4.1 Predicted Fish Losses From Oil Spills\n9.4.2 Socioeconomic Impacts of OCS Development\n129\non Navarin Basin Fisheries\n129\n9.5 Marine Bird Issues\n130\n9.5.1 Oil Effects\n131\n9.5.2 Disturbance Effects\n131\n9.5.3 Geographic Assessments\n134\nMarine Mammal Issues\n9.6\n134\n9.6.1 Oil Effects\n135\n9.6.2 Disturbance Effects\n136\n9.6.3 Geographic Assessments\n137\nSummary and Conclusions\n9.7\n143\nReferences Cited\n157\nNavarin Basin Synthesis Meeting Attendees\nx","Figures\nPage\nFigure\n2\nPlace names in the Navarin Basin OCS planning unit\n1.1\nGeneralized isopach map of sediment thickness above the acoustic\n1.2\n2\nbasement in the Navarin Basin province\nIsopach map of sedimentary strata above the acoustic basement\n2.1\n4\nin the Navarin Basin\n5\nDetailed bathymetry of the northwestern Bering Sea shelf\n2.2\nTracklines of seismic reflection profiles across the Navarin Basin\n2.3\n6\nprovince collected in 1980\n6\nLocation of bottom samples in the Navarin Basin collected in 1980\n2.4\n7\nSeismic reflection profile across the Navarin Basin\n2.5\n8\nMean sediment size in the Navarin Basin and vicinity\n2.6\n8\nWeight percent of sand-sized sediment in the Navarin Basin and vicinity\n2.7\nWeight percent of oxidizable organic matter in the\n2.8\n9\nNavarin Basin and vicinity\nPreliminary map of sediment types in the Navarin Basin province\n2.9\n9\nderived from visual inspection of core samples onboard ship\n2.10 Contour map of weight percent of organic carbon in surface\n10\nsediments from the Navarin Basin province\n2.11 Preliminary map of areas of gas-charged sediment in\n10\nthe Navarin Basin province\n2.12 Preliminary map of areas of sediment waves in\n11\nthe Navarin Basin province\n2.13 Preliminary map of areas of submarine landslides observed in seismic\n13\nreflection records in the Navarin Basin province\n13\n2.14 Earthquakes of magnitude 6 or larger on the Bering Sea shelf, 1900-79\n14\n2.15 All known earthquakes on the northwestern Bering Sea shelf\n14\nPreliminary map of faults in the Navarin Basin province\n2.16\n18\nMonthly statistics for several climate variables\n3.1\n19\nSynoptic maps of mean air temperature during February and August\n3.2\nPercent frequency of observations reporting precipitation\n3.3\n20\nduring February and August\nXI","Page\nFigure\n20\nPercent frequency of occurrence of all fog during February and August\n3.4\nWind speed and direction histograms for Marine Areas A and B\n22\n3.5\n27\nScalar mean wind speeds during February and August\n3.6\n28\nStorm track counts for October-February in heavy and light ice years\n3.7\n29\nPercent frequency of occurrence of waves for Marine Area B\n3.8\nPercent frequency of occurrence of hazardous wave conditions\n3.9\n30\nduring February and August\n32\n3.10 April mean icing conditions\n33\n3.11 November extreme icing conditions\n35\nAverage ice extent during fall and winter\n3.12\n3.13 Terminology for sea ice types and areal distribution\n36\nin the marginal ice zone\n3.14 Relationship between wind speed and ice motion with the\n36\ntrajectory of ice and superimposed wind vectors\n37\n3.15 Trajectory of Buoy 3600, 18 January-23 May 1982\n38\n3.16 Trajectory of Buoy 3603, 21 February-19 June 1981\n42\nHydrographic domains and fronts on the southeastern Bering Sea shelf\n4.1\nGeneral description of circulation and water masses in the Bering Sea\n43\n4.2\nSurface current patterns during July computed from analysis of\n4.3\n43\ngeostrophic currents and currents induced by winds\nResidual tidal and baroclinic currents found from a\n4.4\n44\npreliminary run of the Rand model\nEstimated mean circulation based on direct observations\n4.5\n45\nand inferred geostrophic flow\nVertical distribution of temperature and salinity across the\n4.6\n46\ncentral Bering Sea shelf, 30 March-2 April 1980\nVertical distribution of salinity 10-11 November 1980 illustrating\n4.7\n47\nstratification on the central Bering Sea shelf prior to ice formation\nCurrent-meter mooring locations and mean flows, winter 1980-81\n48\n4.8\nCophase lines for the semidiurnal M2 tidal constituent in the Bering\n4.9\n50\nSea, computed using a vertically integrated numerical model\nxii","Page\nFigure\nCo-tidal chart for the semidiurnal tidal component, computed using\n4.10\n51\nthe three-dimensional model of Bering and Chukchi seas\n52\nComputed 12.5-hour tidal ellipses at 10-m depth\n4.11\nLocations of recently occupied pressure and current stations\n4.12\n53\nin the northern Bering Sea\n54\nCurrent ellipses derived from mooring data\n4.13\nSpecies composition of diatom communities in the surface layer\n5.1\n56\nof the Bering Sea in early to midsummer\n57\nDiatom standing crops in the Bering Sea in early to midsummer\n5.2\nAnnual distribution of primary production over the\n5.3\n58\nsoutheastern Bering Sea shelf\nCharacteristic copepod communities in the Bering Sea in the\n5.4\n58\nupper water layers in early to midsummer\nAverage summer zooplankton biomass in 80-m water column\n5.5\n59\nover a 15-year period, 1956-70\nBenthos associations based on station groups formed by a\n5.6\n60\ncluster analysis of In-transformed density data\nDistribution of combined catches of the Japanese mothership and\n6.1\n67\nSouth Korean fisheries in the eastern Bering Sea in 1980\nDistribution of combined catches of the Japanese mothership and\n6.2\n67\nSouth Korean fisheries in the eastern Bering Sea in 1981\nDistribution and relative abundance of total flatfish during the\n6.3\n68\n1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of total roundfish during the\n6.4\n68\n1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of walleye pollock during the\n6.5\n70\n1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of Greenland turbot during the\n6.6\n70\n1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of Tanner crab, Chionoecetes opilio,\n6.7\n71\nduring the 1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of Tanner crab, Chionoecetes bairdi,\n6.8\n71\nduring the 1981 NWAFC eastern Bering Sea survey\nDistribution and relative abundance of blue king crab during the\n6.9\n72\n1981 NWAFC eastern Bering Sea survey\nxiii","Page\nFigure\n72\n6.10 Main fishing grounds for pink shrimp in the Bering Sea\n78\nSummer distribution of seabirds in the Bering Sea\n7.1\n78\nMarine domains of the Navarin Basin\n7.2\n79\nDensity distribution of all birds in the marine domains of the Navarin Basin\n7.3\n80\nSpring distribution of pelagic birds, Navarin Basin vicinity\n7.4\n80\nSummer distribution of pelagic birds, Navarin Basin vicinity\n7.5\n81\nFall distribution of pelagic birds, Navarin Basin vicinity\n7.6\n82\nMarine birds along the ice front\n7.7\n84\nDistribution of seabird colonies on the eastern Bering Sea shelf-edge islands\n7.8\n93\nSightings of baleen whales in the Navarin Basin and vicinity\n8.1\n95\nSightings of toothed whales in the Navarin Basin and vicinity\n8.2\n97\nMarine mammal haulouts, St. Matthew Island area\n8.3\n99\nSightings of phocid seals in the Navarin Basin and vicinity\n8.4\n100\nSightings of Steller sea lions and walruses in the Navarin Basin and vicinity\n8.5\n107\nGeneral pathways and mechanisms of the fate of oil\n9.1\nRelative magnitudes and timescales of the redistributive\n9.2\n108\nprocesses for the fate of oil spilled at sea\n109\nOil spill trajectory simulations, July-August\n9.3\n110\nOil spill trajectory simulations, September-December\n9.4\n111\nOil spill trajectory simulations, January-June\n9.5\nSchematic of a cross-section of the ocean with surface\n9.6\n112\nwater moving downwind\nDispersed oil profiles, exponential fit to calculated dispersion\n9.7\n113\nrate from the open-ocean oil weathering model\nConcentrations of oil along a transect oriented to the northeast\n9.8\n115\nof the Ixtoc I blowout, September 1979\nEvaluation of encounter risk for birds in the Navarin Basin:\n9.9\n132\nspring, summer, and fall\n9.10 Proximate factors associated with offshore oil exploration and\n133\ntheir effects on marine mammals\nxiu","Tables\nTable\nPage\n2.1\nEarthquakes in the vicinity of the Navarin Basin\n12\n3.1\nPredicted frequency of significant wave heights for waves\ncoming from eight directions in February\n29\n3.2\nPredicted frequency of peak wave periods for waves\ncoming from eight directions in February\n31\n3.3\nPredicted frequency of significant wave heights for waves\ncoming from eight directions in November\n34\n3.4\nPredicted frequency of peak wave periods for waves\ncoming from eight directions in November\n34\n4.1\nBC-26 tidal currents\n49\n6.1\nFinfish species of commercial importance inhabiting the Navarin Basin\n65\n6.2\nRelative importance of major commercial species within the\nNavarin Basin and Bering Sea as measured by average\ngroundfish catches of foreign nations, 1977-79\n66\n6.3\nForeign fishing activity by nation and vessel type\nin the Navarin Basin, 1980-81\n69\n6.4\nForeign fishing activity by number of vessels each\nmonth in the Navarin Basin, 1980-82\n73\n6.5\nAnnual and mean groundfish catches by Japanese vessels within\nthe Navarin Basin, mean Bering Sea catch, and percentage of\nBering Sea catch within the Navarin Basin, 1972-81\n74\n6.6\nEstimated incidental catch of prohibited species by foreign\nfisheries operating in the Navarin Basin and the entire\nU.S. FCZ in the Bering Sea, 1977-81\n74\n6.7\nJapanese mothership gillnet catch of Pacific salmon by 2° X 5°\nblocks in and near the Navarin Basin, 1980 and 1981\n75\n6.8\nEstimated biomass of commercially important crab species\nin the Navarin Basin and in the overall NMFS eastern\nBering Sea summer survey areas of 1980-82\n75\n7.1\nMean density of birds in the Navarin Basin by domain\n81\n7.2\nBird density indices for seasons and habitats in the eastern Bering Sea\n83\n7.3\nTransects with more than 100 birds, Navarin Basin\n85\n7.4\nBreeding bird colonies, eastern Bering Sea shelf edge\n86\nXU","Page\nTable\nRelative importance of prey types in the diets of cetaceans\n8.1\n96\nin the eastern Bering Sea\nSightings of cetaceans and estimates of their abundance\n8.2\n98\nin the Navarin Basin, 1982-83\nRelative importance of prey types in the diets of pinnipeds\n8.3\n101\nin the eastern Bering Sea\nParameters of selected major oil spills\n116\n9.1\nLethal concentrations of petroleum for various life history stages\n9.2\nand ecological groupings of fish and shellfish\n122\nSources and types of information used in oil spill damage\n9.3\nassessment for selected finfish species of the Navarin Basin\n123\nRelative seasonal abundance of major finfish species\n9.4\n123\ninhabiting the Navarin Basin\nSeasonal distribution of selected finfish species, eastern Bering Sea\n124\n9.5\n9.6 Spawning periods for selected finfish species of the Navarin Basin\n125\n9.7 Vertical distribution of eggs and larvae of major finfish species by season\n125\nMean female age, size, weight, and fecundity at maturity for\n9.8\nselected fishes inhabiting the Navarin Basin\n126\nKey growth parameters and calculations used in estimating\n9.9\ndensities of finfish eggs and larvae in the Navarin Basin\n126\n9.10 Relative seasonal composition of major commercial finfish species\ninhabiting \"deep\" and \"shelf\" waters of the Navarin Basin\n127\n9.11 Seasonal biomass estimates of major commercial finfish species\ninhabiting \"deep\" and \"shelf\" waters of the Navarin Basin\n127\n9.12 Estimated numbers of females, eggs, and larvae per square\nkilometer for four finfish species inhabiting the Navarin Basin\n128\n9.13 Estimated finfish egg and larval mortality over a 10-km2 zone\nof hydrocarbon contamination in the Navarin Basin\n129\n9.14 Estimated losses at replacement of fishable adults over a 10-km2\nzone of hydrocarbon contamination in the Navarin Basin\n129\n9.15 Summary of occurrence rates for accidental oil spills currently\nused in the MMS oil spill trajectory analysis model\n137\nxvi","Chapter 1.\nGeography and Physiography\nJOSEPH G. STRAUCH, JR.\nScience Applications, Inc., Boulder, Colorado\nThe continental slope covers an area of 40,000\n1.1 GEOGRAPHY\nkm2 between the 150- and 2,800-m isobaths. It is\ndissected by five large canyon systems; from north\nThe Navarin Basin OCS planning unit is remote;\nto south they are Navarinsky, Pervenets, St.\nthe nearest point of continental land is Cape\nMatthew, Middle, and Zhemchug canyons. St.\nNavarin (U.S.S.R.), 150 km northwest of the\nMatthew and Middle canyons are newly discovered\nplanning unit boundary (Fig. 1.1). Two small\nfeatures recently described by Carlson et al. (1983).\nuninhabited islands, St. Matthew and Hall, are\nThe large canyon systems of the Navarin Basin\nlocated to the east of the planning unit; they are\nprovince are believed to have been formed when\npart of the Bering Sea National Wildlife Refuge.\nglacio-eustatically lowered sea level exposed the\nSt. Lawrence Island is located about 300 km north\nBering Sea shelf to a present-day depth of about\nof St. Matthew Island and has several permanent\n150 m, thus allowing major rivers entering the sea\nsettlements and two airstrips. The Pribilof Islands\nto carry large amounts of sediment to the shelf\nare about 450 km south of St. Matthew Island.\nedge. Slumps and turbidity currents likely were the\nprimary canyon-cutting agents. The shapes of the\n1.2 PHYSIOGRAPHY\ncanyons are thought to be controlled by structures\nas old as Paleogene (Scholl et al. 1975). Continental\nThe physiography of the Navarin Basin province\nslope gradients range from 3° to 10°, as compared\nhas been described by Fischer et al. (1982). The\nto a world average of 4.3° (Shepard 1963).\nprovince comprises a very flat continental shelf,\nThe continental rise begins at the 2,800-m\na steep continental slope incised by several large\nisobath and continues beyond 3,600 m depth. It\ncanyons, and a gentle continental rise. The\nis dissected by many deep sea channels, including\ncontinental shelf within the Navarin province\nthose extending from the five canyon systems.\nencompasses an area of some 100,000 km²\nGraded sediments in and near the channels are\nbetween the 100- and 150-m isobaths. It has\nsuggestive of turbidity current deposition.\ngradients of 0.04° to 0.01° and a width of 100-250\nThe sedimentary basins in the Navarin Basin\nkm. The Bering shelf is one of the flattest in the\nplanning unit that may hold petroleum are located\nworld. Two ridges having very gentle surface\napproximately between the 100- and 200-m\nexpressions. Pervenets Ridge and Navarin Ridge.\ncontours (Fig. 1.2). These basins are described in\nlie on the outer shelf. The shelf break occurs be-\nChapter 2.\ntween the 150- and 175-m isobaths.","Navarin Busin Synthesis\n2\n150\n160\n175\n180\n175\n17C\n165\n63\nGulf of Anadyr\nGambell - Savoonga\n63\nKorak\nKulowiyi\nCoast\nCape Navarin\nST. LAWRENCE\n61\nISLAND\nPERVENETS\n61\nRIDGE\nHall Island\nNAVARINSKY\nNAVARIN\nCANYON\nSarichef Strait\n59\nRIDGE\nNome\nST. MATTHEW\nPERVENETS\nISLAND\nNUNIVAK\n59\nCANYON\nMIDDLE\nISLAND\nCANYON\n57\nST. MATTHEW\nWairus Island\n57\nCANYON\nSt Paul Island\nOtter Island\n1\nZHEMCHUG\nPRIBILOF ISLANDS\nCANYON\nSt. George Island\n55'\nCold Bay\n55\nMorzhovoi Bay\nUnimak Pass\nDutch Harbor\n53'\nALEUTIAN BASIN\nUnalaska\n53\n1.\n/204m\nFIGURE 1.1-Place - names\n200\n51\nin the Navarin Basin OCS\n200m\nplanning unit and adjoin-\n51\n160\n175°\n170°\n165\n180\ning area.\n175°\no\n170 o\no\no\n180'\n175\n50\n0\n100\n200 km\n63°\nO\n63\n50\n0\n50\n100 mi\nNavarin Basin\nProvince\n3\n61\no\n61\nSEDIMENT THICKNESS\n59\n< 1km\no\n59\nFIGURE 1.2-Generalized\n1-2km\nisopach map of sediment\nthickness above the a-\n> 2km\ncoustic basement in the\n57\nNavarin Basin province.\n(Adapted from Marlow et\no\n175°\n170°\n175\no\n180\nal. 1981.)","Chapter 2.\nGeology\nROBERT S. PETERSON\nScience Applications, Inc., Boulder, Colorado\nMost of the available information regarding the\nsuch as faults, gas-charged sediment, and slump\ngeology of the Navarin Basin is derived from\nfeatures; and (2) bottom topography. Bottom\ninterpretation of seismic profiling records, a survey\nsamples of surface sediment provide data on (1)\ntechnique used by geophysicists and geologists to\ngeotechnical properties that are important for the\ndetermine the structure of both unconsolidated\ndesign of platforms and pipelines; (2) recent\nand consolidated deposits to depths of several kilo-\ngeological history of the basins; and (3) sediment\nmeters. The lower depth limit, beneath which\ntransport processes that may become hazards to\nseismic profiling cannot resolve structure, is de-\noffshore structures, especially movement of large\nfined as the acoustic basement and often\nbedforms and slope instability.\nrepresents the boundary between sedimentary\nrocks and older igneous or metamorphic rocks.\n2.1 STRUCTURAL FRAMEWORK\nThe basins and ridges referred to in the follow-\ning discussion are generally defined by topography\nThe structure and evolution of the Navarin Basin\non this acoustic basement and not necessarily by\nprovince have been described by Marlow et al.\nthe topography on the sea floor. Thus, a basin\n(1976, 1983) and Marlow (1979). The province\nrepresents an area where sediments have accumu-\ncomprises three large basins, each of which may\nlated over time and where hydrocarbons may be\ncontain up to 15 km of sedimentary fill. Most of\nproduced or may accumulate.\nthis fill is Cenozoic (less than 70 million years old),\nFigure 2.1 shows the thickness of strata overly-\nalthough some portion may be from the upper\ning the acoustic basement. The Navarin Basin\nMesozoic (70 to 120 million years). The Navarin\nprovince consists of several northwest-trending\nBasin is enormous compared to the other basins\nbasins that are defined either by contours on the\nof the Bering shelf; the volume of sedimentary fill\nacoustic basement or isopach lines of sediment\nmay exceed 400,000 km³, and the area is roughly\nthickness above the acoustic basement (Chase et\n80,000 km². About 85% of the basin is less than\nal. 1979; Cooper et al. 1979; Marlow et al. 1981).\n200 m beneath the surface of the ocean.\nNote that the basins are not necessarily defined\nThe sedimentary rocks in the southern portions\nby the seafloor topography (Fig. 2.2).\nof the province are essentially undeformed, al-\nThe most recently acquired nonproprietary data\nthough minor normal faults have been observed\non sub-bottom geology and surface sediments are\nin seismic reflection profiles along the flanks of\nfrom U.S. Geological Survey (USGS) research\nthe individual basins (Fig. 2.5). These faults are\ncruises during the summers of 1980 and 1981. The\ncontemporaneous with basin filling and do not rep-\nseismic reflection survey tracklines and bottom\nresent tectonic activity involving crustal motions.\nsample locations from the 1980 cruise are shown\nIn the northern portions of the province. the\nin Figures 2.3 and 2.4. The 1981 cruise was in the\nsedimentary strata have been gently folded into\nsame general area. The seismic reflection surveys\nbroad. 10- to 15-km-wide anticlines. The forces pro-\nreveal information on (1) structures in uncon-\nducing these folds may have been either lateral\nsolidated sediment that may be geological hazards,\ncompression or diapiric intrusions: the cause is\n.3","Navarin Basin Synthesis\n4\nO\n175°\n170°\n175°\n180°\n63°\n63\n61\n61\n59\n59\nFIGURE 2.1 - -Isopach map\n57\nof sedimentary strata\n57°\nabove the acoustic base-\nment in the Navarin\nBasin. (Adapted from\n180°\n175°\n175\n170°\nMarlow et al. 1981.)\n2.2 SURFICIAL SEDIMENTS\nspeculative at this time.\nPrimary sources which have provided sedimen-\nThe general characteristics of surficial deposits\ntary materials to the Navarin basins are the high\non the Bering shelf (Figs. 2.6-2.8) have been com-\nland areas surrounding the Bering Sea on the\npiled by Sharma (1979). As one moves westward\nNorth American and Asian continents. The Yukon,\nacross the Bering shelf, sediments display finer\nKuskokwim, and Anadyr rivers apparently have\naverage grain diameters, smaller percentages of\nbeen major contributors of material throughout the\nsand-sized material, and increased proportions of\nCenozoic. During ice ages, numerous rises and falls\norganic matter. In the Navarin Basin area, surface\nin sea level have resulted in a variety of deposi-\nsediments are typically less than 7 in grain\ntional environments, some of which are conducive\ndiameter (i.e., very fine silt), contain 25% or less\nto the formation of source and reservoir beds for\nby weight of sand-sized material, and are relatively\nhydrocarbons.\nhigh in oxidizable organic matter, containing about\nAs of 1982, no wells had been drilled into the\nbasins, and hence, no samples of the basin fill were\n1% by weight.\nSediment samples collected during the summer\navailable. The geologic history of the basins,\n1980 and 1981 field seasons by the USGS reveal\ninferred from reconnaissance geophysical surveys,\nconsiderably more detail about the surficial\nsuggests that the sediments were deposited in a\nsediments in the planning unit. Sands and silts\nneritic (i.e., shallow water: deltaic, shoreline,\npredominate on the continental shelf and slope.\ncontinental shelf) environment. Neritic sediments\nCoarse silt and sand occur at the shelf edge, on\ntypically have coarse texture, high organic con-\nthe upper slope and in the heads of submarine can-\ntent, high porosity, and high permeability. All of\nyons. Preliminary analyses based on 14C dating of\nthese characteristics contribute to suitability for\nsediment core segments suggest that accumula-\nhydrocarbon generation and migration.","Geology\n5\n178\n180\nO\n178\nO\n176\n174\nO\n172\nO\n170\n150\n61\nO\n61\nO\n200\n800\nSt. Matthew Island\n2000\n60\nO\n60\no\n59\n59\no\n58\n58\nSt. Paul Island\n50\n57°\n57°\n0\n20\n40\n60\n80\n100\nkm\n180\nO\n178 o\n176\no\n174\n172 o\nFIGURE 2.2-Detailed - bathymetry of the northcentral Bering Sea shelf. (Adapted from Karl and Carlson 1983.)\ntion rates of the uppermost 6 m of sediment range\nriverine sediment sources are over 400 km away.\nfrom about 10 to 25 cm/1,000 yr over the continen-\nFigure 2.9 is a preliminary map of sediment\ntal shelf (Carlson and Karl 1983). It is not evident\ntypes and shows the high density of station loca-\nwhich of a number of processes is responsible for\ntions during the USGS cruises. Figure 2.10 shows\nthe observed sediment distribution pattern. The\nthe amount of oxidizable organic matter in the\ncoarser sediments on the outer shelf may be relict,\nsediment, which provides information on sediment\nhaving formed when sea levels were lower and\nprovenance and productivity in the water column.\nshorelines were in these areas. Alternatively, they\nAdditional sediment samples are required in order\nmay be the result of local winnowing of finer\nto provide information on depositional processes,\nfractions. Or, the finer sediments elsewhere may\nboth present and past, that control sediment distri-\nsimply represent dilution of relict sediments by\nbution in the planning unit.\nfines following flooding of the shelf. Present\nThe geotechnical characteristics of sediments in","Navarin Basin Synthesis\n6\n175°\n170°\n180°\n175°\n50\n0\n100\n200 km\n63°\no\n63\n50\n0\n50\n100 mi\n50\n61\n61\n59\n59\nFIGURE 2.3 - -Tracklines of\nSEISMIC TRACKLINES\n57\nseismic reflection profiles\nAll seismic systems\n57°\n3.5 kHz only\nacross the Navarin Basin\nprovince collected in 1980.\n(Adapted from Carlson\n180°\n175°\n170°\n175°\nand Karl 1981.)\n175°\n170°\n175°\n180°\n50\n0\n100\n200 km\n63°\no\n63\n50\n0\n50\n100 mi\n61\n61\n59\n59\nFIGURE 2.4-Location of\n57\nbottom samples in the\n57\nNavarin Basin province\ncollected in 1980. (Adap-\nted from Carlson and Karl\n180°\n175°\n170°\n175°\n1981.)","Geology\n7\n175°\nO\n180°\n170\n175°\n50\n0\n100\n200 km\n63°\no\n63\n50\n0\n50\n100 mi\nB - 92\nLine\n1800\n1900,\n2000\n61\n2100\n2200\n2300\n61\n0000\n0100\n0200\n0300,\n0400\n0600\n0700\n0800\n1000\n1200\n59°\n59\n57°\n57\n180° O\n175°\n170°\n175°\nLine B-92\nNunivak Arch\nNavarin Basin\n176°W\n60° 78°W\n177°W\n61'N\nFIGURE 2.5-Seismic\nI\n2000\n1900\n1800 HR\n1300\n1200\n1100\n1000\n0900\n0800\n0700\n0600\n0500\n0400\n0300\n0200\n0100\n0000\n2300\n2200\n2100\n0\nreflection profile across\n0\n1\nthe Navarin Basin. (Adap-\n2\nted from Marlow et al.\n3\nKM\nSEC\n1976.)\nexposed by slumping or erosion.\nthe uppermost 2 m of the Navarin Basin have been\nWater content of shelf sediments at 1 m sub-\ndescribed by Edwards and Lee (1983). Shelf sedi-\nbottom depth ranges from 20 to 137%. The highest\nment samples typically have undrained vane shear\nvalues are associated with the zone of weak sedi-\nstrengths of 2 to 22 kPa. (6.9 kPa = 1 psi.) A zone\nment 150 km west of St. Matthew Island. At 2 m\nof relatively weak sediment occurs about 150 km\nsub-bottom depth, water contents range from 43\nwest of St. Matthew Island. It is followed farther\nto 107%.\nwest by a relatively high shear strength (> 15 kPa)\nObserved values of grain-specific gravity range\nzone adjacent to Pervenets Ridge. A zone of\nfrom 2.55 to 2.77 and average 2.64. The lighter\nrelatively high (> 10 kPa) shear strength sediments\nvalues are indicative of the presence of diatoms.\nwas located to the southeast near the head of\nAtterberg limit tests show that the Navarin Basin\nZhemchug Canyon. Shear strengths of cores from\nshelf sediments are of medium to high compress-\nthe continental slope ranged from 2 to 51 kPa at\nibility and are more highly compressible in the\na sub-bottom depth of 1 m. being generally high\nnorthern part of the province near Navarinsky\n(> 10 kPa) at the heads of canyons and usually less\nCanyon. Consolidation tests show that Navarin\nthan 5 kPa on the lower slope. High (38-51 kPa)\nBasin sediments are overconsolidated and have\nshear strengths on the slope appear to be\nvery high overconsolidation ratios- an unlikely\nassociated with overconsolidated. older sediments","Navarin Basin Synthesis\n8\n175°\n170 O\n180°\n175°\n2\n3\no\n5\n63°\n50\n0\n100\n200 km\n1\nO\n63\n2\n50\n100 mi\n50\n0\n61\n61\n59\n59\nFIGURE 2.6-Mean - sedi-\nment size (phi units) in the\n57\nNavarin Basin and vicini-\n57°\nty. In the Navarin Basin,\nmean size is 8 or less.\n(Adapted from Sharma\n175°\n170°\n180°\n175°\n1979.)\n175°\n170°\n180°\n175°\n63°\n200 km\n50\n0\n100\n50\n50\n63\n75\n50\n100 mi\n50\n0\no\n61\n61\n59\n59\n50\n75\no\n57\nFIGURE 2.7-Weight per-\n57°\n25\ncent of sand-sized sedi-\nment in the Navarin Basin\nand vicinity. (Adapted\n175°\n180°\n170°\n175°\nfrom Sharma 1979.)","Geology\n9\n175°\n175°\n180°\n170\no\n50\n0\n100\n200 km\n63°\no\n63\n50\n0\n50\n100 mi\n6\n61\n59\n59\n0.5\no\n57\nFIGURE 2.8-Weight per-\n57\ncent of oxidizable organic\nmatter in the Navarin\nBasin and vicinity. (Adap-\n175°\n180°\n175°\nO\n170°\nted from Sharma 1979.)\no\n180°\no\n175°\n170°\n175\n50\n0\n100\n200 km\n63°\nO\n63\n50\n0\n50\n100 mi\n50\n61\n61\n3\n50\n59\n59\nFIGURE 2.9-Preliminary\nmap of sediment types in\nSEDIMENT TYPES\nthe Navarin Basin prov-\n57\nince derived from visual\nSandy gravel\nSandy mud\n57\ninspection of core samples\nSand\nMud\nonboard ship. (Adapted\nfrom Carlson and Karl\n180\n175°\n175\n170°\n1981.)","Navarin Basin Synthesis\n10\n175°\n170'\n180°\n175°\n63°\n50\n0\n100\n200 km\n63\n50\n0\n50\n100 mi\n61\n61\n€1.25\n1.50\n59\n59\nFIGURE 2.10 - -Contour\nmap of weight percent of\norganic carbon in surface\n57\nsediments from the\n0.50\n57°\nNavarin Basin province.\n1.00\nContour interval 0.25%.\n(Adapted from Carlson\n175°\n180°\n170°\n175°\nand Karl 1981.)\n175°\n170°\n180°\n175°\n63°\n50\n0\n100\n200 km\nO\n63\n100 mi\n50\n0\n50\n61\n61\n59\n59\nFIGURE 2.11 - -Preliminary\n57°\nmap of areas of gas-\no\n57\ncharged sediment in the\nNavarin Basin province.\n(Adapted from Carlson\n175°\n180°\n170°\n175°\nand Karl 1981.)","Geology\n11\no\n175\n170°\n175°\n180\n50\n0\n100\n200 km\n63°\n63\n100 mi\n50\n0\n50\n61°\n61\n59\n59\nFIGURE 2.12-Preliminary\n57°\nmap of areas of sediment\n57\nwaves in the Navarin\nBasin province. (Adapted\nfrom Carlson and Karl\n175'\n170°\n180\n175\n1981; Marlow et al. 1981).\ncircumstance given other sediment properties\nbiogenic origin. However, a possible thermogenic\nobserved. The cause of the overconsolidation is\nsource was indicated at a station in Pervenets\nCanyon.\nuncertain.\nUSGS geophysical records and geochemical\n2.3 SEDIMENT MOVEMENT\nsampling suggest that gas-charged sediments are\ncommonplace in the upper 200 m on the outer\nLarge sediment waves were found by the USGS\nshelf of the Navarin Basin province (Fig. 2.11).\nat the heads of Zhemchug, Pervenets, and Navarin-\nHowever, because no geochemical sampling has\nsky canyons (Fig. 2.12). In Navarinsky Canyon the\nyet been done below 5 m sub-bottom depth, it is\nwave field covers an area of 1,400 km2 between\nnot possible to firmly correlate deeper observed\nthe 215- and 450-m isobaths. The crests of the bed-\ngeophysical anomalies to gas-charged sediments.\nforms have a north-south trend. The distance\nSlope sediments have the highest concentrations\nbetween crests is about 600 m, while crest heights\nof gases, followed by shelf and rise sediments,\naverage 5 m and reach maxima of 15 m. The\nrespectively. Methane was the most abundant\nhydrocarbon gas observed in samples from sedi-\nstratigraphic unit containing the sediment waves\noverlies a flat-lying reflector and attains a max-\nment cores (Golan-Bac and Kvenvolden 1983),\nimum thickness of 120 m. It is not currently known\nwhere it was typically present in concentrations\nwhether these features are active.\ntwo or three orders of magnitude greater than the\nSubmarine slides have been observed at numer-\nother low-molecular-weight (C2-C4) hydrocarbons\nous locations in the Navarin Basin between depths\nexamined. Maximum concentrations of methane\nof 150 m and more than 1,200 m (Fig. 2.13). Zones\nexceeded 1,000 ul/liter in five cores from Navarin-\naffected by down-slope movement are up to 50 km\nsky Canyon. but generally were less elsewhere.\nlong and as much as 25 km wide. In some cases\nMost of the methane and other hydrocarbon gases\nthe slides may affect the upper 200-300 m of the\nin the Navarin Basin sediments appear to be of","Navarin Basin Synthesis\n12\na trackline (refer to Fig. 2.3 for trackline locations).\nsediment column. The morphological features of\nWith one exception. shown by the dashed line in\nthe slides indicate that slumps. debris-flow deposits,\nFig. 2.16, faults cannot be correlated between\nand mudflow deposits are present. The slides are\ntracklines with any confidence, due to the wide\nthought to have been triggered by seismic ground\nspacing between tracklines. The pattern of fault\naccelerations.\ncrossings, however, reflects a prevalence of cross-\nings on tracks normal to the shelf edge and\n2.4 SEISMICITY AND FAULTING\nrelatively few on tracks parallel to the shelf edge.\nThis suggests that most faults trend northwest-\nThere are no records of earthquakes of mag-\nsoutheast, or parallel to the shelf edge. The ma-\nnitude 6 or larger from the Navarin Basin (Fig.\njority of the faults are on the continental slope and\n2.14). However, because of the remoteness of the\noutermost shelf (Carlson et al. 1982). None of the\narea from seismic stations, small earthquakes may\nfaults mapped during the 1980-81 USGS cruises\nhave gone undetected. Locations of earthquakes\ncuts the Holocene sea floor. Based on sediment\nthat have been recorded on the northwestern Ber-\naccumulation rate and faunal evidence, the faults\ning shelf are shown in Figure 2.15. Data for all\nthat reach to within 3 m of the sea floor should\nknown events in the vicinity of the Navarin Basin\nbe considered active (Karl and Carlson 1983).\nplanning unit are listed in Table 2.1. The record\nof small earthquakes is incomplete; however, the\n2.5 PETROLEUM POTENTIAL\nrecord of large earthquakes (> magnitude 6) that\nhave occurred since the turn of the century is\nNo offshore drilling had occurred in the Navarin\nprobably complete (Fig. 2.14).\nBasin as of 1982. Analysis of the petroleum poten-\nA preliminary map of faults that have been iden-\ntial is based primarily on the thickness and struc-\ntified in the USGS seismic reflection records is\nture of sedimentary strata, as determined from\nshown in Fig. 2.16. Each dot on the map indicates\nseismic reflection profiles, and on the inferred\nthat a fault is present at a particular place along\nTABLE 2.1-Earthquakes in the vicinity of the Navarin Basin.\nIntensity\nTime\nLocation\nDate\nMap\nor\nHour\nMinute\nSecond\nLatitude\nLongitude\nMagnitude#\nNo.\nYear\nMonth\nDay\n57.000N\n170.000W\nV\n1\n1835\n04\n14\n-\n-\n-\n57.000N\n170.000W\nVII\n2\n1836\n04\n02\n-\n-\n-\n57.000N\n170.000W\nV\n3\n1836\n08\n-\n-\n-\n-\n59.500N\n170.000W\nV\n03\n4\n1861\n05\n-\n-\n-\n60.000N\n175.000E\n20\n58\n36\n5\n1925\n05\n27\n-\n06\n04\n50\n00.0\n62.000N\n179.000W\nIV\n6\n1929\n04\n24\n61.700N\n177.500E\n5.6 (unspec.)\n7\n1933\n09\n07\n22\n39\n173.000E\n5.6 (unspec.)\n8\n1934\n03\n09\n14\n02\n30\n63.000N\n179.000W\n21\n21\n00\n15.0\n59.000N\n9\n1949\n01\n-\n56.500N\n170.000W\nV\n13\n00\n00.0\n10\n1954\n05\n16\n11\n1965\n10\n22\n16\n26\n50.3\n56.600N\n169.700W\n4.7 (mb)\n27\n18\n41\n57.8\n57.571N\n169.940W\n4.2 (mb)\n12\n1977\n03\n4.2 (mb)\n26\n02\n52\n56.5\n57.615N\n169.925W\n13\n1978\n06\nSOURCE: NOAA, Environmental Data Services earthquake file.\nRefer to Figure 2.15.\n+ Locations for earthquakes prior to 1929 are estimates only.\n+ Intensity is a subjective measure of earthquake size based on felt effects or damage to structures. It is shown here in roman\nnumerals representing the Mercalli scale. Magnitude is an earthquake size measure based on instrumentally recorded\nmeasurements. In this table the type of ground motion magnitude specified is body wave motion (mg).","Geology\n13\n175°\n180°\n175°\n170°\n50\n0\n100\n200 km\n63°\n63°\no\n50\n0\n50\n100 mi\n61\n61\n59\n59\nFIGURE 2.1 13 - Preliminary\nmap of areas of subma-\nrine landslides observed\n57°\nin seismic reflection\n57\nrecords in the Navarin\nBasin province. (Adapted\nfrom Carlson and Karl\n175°\n180°\n175°\n170°\n1981.)\n170°\n175°\n180°\n175°\n170°\n165\n160\n155\n150\n65\nAD\n65\n62\n62\n59\n59\nAs\n56\n56\nFIGURE 2.14 - Earth-\nquakes of magnitude 6 or\nlarger on the Bering Sea\n53\n53\nshelf, 1900-1979 - (Data\nA\nsource: NOAA. Environ-\nmental Data Service.)","Navarin Basin Synthesis\n14\n175°\n170°\n180°\n175°\n50\n0\n100\n200 km\n63°\no\n63'\n8\n50\n0\n50\n100 mi\n6\n61\n61\n5\nO4\n59\n59\nO\n9\n12\n13\n2\nFIGURE 2.15-All known\n1\n57\nof\nearthquakes on the north-\n3\n57\n11\nwestern Bering Sea shelf.\n10\nNumbers refer to Table\n2.1. (Data: NOAA, Envi-\n175°\n180°\n170°\n175°\nronmental Data Service.)\n175°\nO\n170°\n180°\nO\n175°\n50\n0\n100\n200 km\n63°\nO\n63\n50\n0\n50\n100 mi\n61\no\n61\n59\n59\nFAULTS\n57\nFIGURE 2.16-Preliminary\nPossible\n57°\nProbable trace\nmap of faults in the\nNavarin Basin province.\n(Adapted from Carlson\n175°\n180°\n170°\n175°\nand Karl 1981.)","Geology 15\ngeologic history of the basin.\n(Burlin and Arkhipov 1973; Marlow 1979). It is\nFor a region to have a high potential for\nthought that these Cenozoic deposits are of the\nhydrocarbons, the sedimentary basin must contain\nsame age and general lithology as those of the off-\na sufficient thickness of hydrocarbon source beds,\nshore basins. Hydrocarbons have been found in\nporous and permeable strata to act as reservoirs,\nthese test wells, but many were dry holes; none\nand stratigraphic traps to contain the hydrocar-\nhas gone into production.\nbons. Although sufficient thickness of strata is well\nThe Navarin Basin province is considered to be\ndocumented for the Navarin Basin, information on\na \"frontier shelf area of significant hydrocarbon\nreservoir beds and stratigraphic traps is more\npotential\" (Marlow 1979; Marlow et al. 1981)\nspeculative at present (Marlow et al. 1976).\nbecause of (1) the great thickness of sedimentary\nSome indication of petroleum potential of the\ndeposits in the basin; (2) the probable existence\nbasin can be obtained from wells drilled into struc-\nof source and reservoir rocks; (3) pinchouts and\ntures on the Alaska Peninsula (Alaska Environmen-\nother stratigraphic traps observed in seismic\ntal Information and Data Center 1974), on the\nrecords; and (4) the similarity of offshore basins\ncoastal lowland surrounding the Gulf of Anadyr\nto onshore basins, especially those in Siberia,\n(Meyerhoff 1972), and into the Khatyrka Basin\nknown to have high hydrocarbon potential.","","Chapter 3.\nMeteorology, Sea Conditions, and Sea Ice\nMAURI J. PELTO\nU.S. Department of Commerce, NOAA, National Ocean Service, Office of Oceanography and Marine Services,\nOcean Assessments Division, Alaska Office, Juneau, Alaska\nAND\nROBERT E. PETERSON\nScience Applications, Inc., Boulder, Colorado\n3.1 CLIMATE\nfrequency of occurrence of precipitation for the\nBering Sea are shown in Figures 3.2 and 3.3.\nThe marine climatology of the Bering Sea has\nAlthough most of the precipitation occurs during\nbeen summarized by Overland (1981). The climate\nsummer, its frequency of occurrence is greater in\nover most of the Bering Sea is classified as polar\nwinter. This probably happens because the relative\noceanic, which indicates that the mean monthly\nhumidity of cold, dry arctic and continental air\ntemperature for the warmest month is 10°C or less\nmasses covering the region in winter is lower than\nand that annual precipitation ranges from 30 to\nin summer. Also, most of the precipitation report-\n50 cm. During the summer months, June through\ned in winter falls as snow.\nAugust, maritime air masses are the predominant\nLow visibility conditions, where visibility is less\ninfluence on the climate in the Navarin Basin\nthan 3.3 km, occur in 20-30% of the observations\nregion, producing winds from nearly any direction.\nin the Navarin Basin region in February (Brower\nDuring the winter period, from September through\net al. 1977). In August, low visibility occurs in about\nMay, air masses from the north and northeast bring\nthe same percentage of observations. Fog occurs\ncold weather and strong winds from a north-\nrarely in February, with less than 5% of observa-\neasterly direction. A summary of cycles of selected\ntions reporting fog (Fig. 3.4). Fog occurs more\nclimate factors for the Navarin Basin region is\nfrequently in August, being encountered 30-35%\npresented in Fig. 3.1.\nof the time (Fig. 3.4).\nSurface winds in the Navarin Basin region are\ngenerally north and northeasterly in winter, and\n3.2 WEATHER\nfairly evenly distributed over all directions during\nthe summer (Overland 1981). Figure 3.5 shows\nMonthly precipitation and mean temperature\ndata from Northeast Cape on St. Lawrence Island\nhistograms of wind data for Marine Areas A and\nprovide indications of conditions in the Navarin\nB, which include part of the Navarin planning unit.\nWinds during the winter from all directions are\nBasin region. The monthly mean temperature at\nNortheast Cape varies from about - -17°C in Feb-\ngreater than 8.5 m/s 50% of the time and have\na mean speed of 11 m/s. During the summer, they\nruary to 8°C in July, and mean total precipitation\nare greater than 8.5 m/s between 30 and 40% of\nvaries from a high of 113 mm in September to a\nlow of 9.4 mm in April (Overland 1981). Most of\nthe time with a mean of 8 m/s (J. E. Overland pers.\ncommun. 1982).\nthe precipitation occurs during the summer\nIn February scalar mean wind speeds are 9 m/s\nmonths when relatively warm and moist air\nin the Navarin Basin region; in August they are\nmasses from the southwest flow over the region.\nlower, averaging 7 m/s (Fig. 3.6).\nSynoptic maps of mean air temperature and the\n17","Navarin Busin Synthesis\nis\nMONTHLY CLIMATE\n21\n40\n20\n-8\n10\n40\nCloud cover (in 1/a's of the sky)\n19\n-7\n8\n35\n30\nPrecipitation (% of observations\nreporting precipitation)\n18\n-6\n6\n30\nScalar mean wind speed (knots)\n17\n-5\n4\n25\n20\nWave heights (% of observed\nwaves >3 m)\n16\n2\n20\n15\n0\n15\n10\nMean air temperature (°C)\n14\n-2\n10\n13\n-4\n12\n0\nD\nJ\nF\nM\nA\nM\nJ\nJ\nA\nS\nO\nN\nFIGURE 3.1-Monthly statistics for several climate variables. (Data source: Brower et al. 1977.)\n3.3 STORM TRACKS\nous wave conditions occur most frequently in the\nsouthern area of the Navarin Basin in winter, and\nMost storms move from west to east along the\nin the northern area in summer (Fig. 3.9).\nsouthern boundary of the Bering Sea and are\nDeep-water wave statistics for the Navarin Basin\nassociated with a low pressure region normally\nhave recently been hindcast by Kozo (1983a) using\nlocated in the vicinity of the Aleutian Island chain.\nHasselmann's parametric wind-wave model. The\nThe frequency of storms in the southern Bering\ncalculations employed regional wind statistics\nSea, which are associated with this region of low\nobtained in 1981-82 from ocean buoys and a land\npressure, is generally higher in winter than in\nstation on St. Matthew Island, as well as World War\nsummer, and the winter storms are more intense\nII meteorological data from the island (Kozo\n(Overland 1981). During summer, storm tracks are\n1983b). Fetch corrections were made for periods\noften displaced northward, in a direction toward\nwhen ice cover is present. Hindcast maximum\nthe Navarin Basin area. Typically, four to five\nsignificant wave heights and peak wave periods\nstorms occur per month during winter (September\nfor the Navarin Basin are 13 m and 16 S, respective-\nto May), and three to four per month during sum-\nly; they occur in February and November (Tables\nmer (June to August).\n3.1-3.4). During months when ice coverage was\nThe location of major storm tracks in winter\npresent, most extreme wave events occurred dur-\nvaries considerably from year to year. There is\ning periods when winds blew from the north,\na \"see-saw\" oscillation of track locations between\nnortheast, and east. Typical wave heights and peak\ntracks over and to the west of the Navarin Basin\nwave periods during winter were 1-5 m and 6-10\nand over the Aleutian Islands. The number of\nS, respectively. During summer, winds and waves\nstorms to the west is much greater in light ice\nhave relatively little directional preference; hind-\nyears than in heavy ice years (Fig. 3.7).\ncast wave heights and periods then were predom-\ninantly 1-3 m and 4-8 S, respectively.\n3.4 SEA CONDITIONS\n3.5 SUPERSTRUCTURE ICING\nIn Marine Area B, potentially hazardous high\nwaves, those higher than 3.5 m, occur most fre-\nSuperstructure icing is a little studied but poten-\nquently in November (Fig. 3.8). Potentially hazard-\ntially hazardous condition prevalent in the Bering","Meteorology, Sea Condition, & Sea Ice\n19\n150\n160\n155°\n175°\n180\n175\n170'\n165\n165\n170\n2\n63\"\n63\nto\n61°\n617\n12\n10\n59°\n59\n-8\n-6\n57°\n57\n-4\n55\n55\n2\no\n53°\n53\nFEBRUARY\n51°\n51'\n165\n160\n175\n170\n175\n180°\n165\n170\n175\n180\n175\n170\"\n165\n160\n155\n150\n63\"\n63\n8\n61\n61'\n59\n591\n57\n57\n55\n55\n9\n53\n53\nFIGURE 3.2-Synoptic\nmaps of mean air temper-\nature (°C) during Febru-\n10\nAUGUST\n51\nary and August. (Adapted\n175\n165\n160\n180\n175\n170\nfrom Brower et al. 1977).","Navarin Busin Synthésis\n20\n25\n90\n80\n70\n60\n55\n59\n59\n30\n57\n95\n>45\n40\n55\n90\n55\n35\n25\n80\n53\n53\n30\n5\nFEBRUARY\n175\n180\n175\n170\n165\n160\n150\n165\n170\n175\n180\n175\n170\n165\n160'\n155\n63\n63\n15\n61)\n61\n20\n59\n59\n57\n57\n25\nFIGURE 3.3-Percent - fre-\nquency of observations\n25\n55\n55\nreporting precipitation\n20\nduring February and Aug-\nust. Dashed lines in Febru-\n53'\n53\nary map represent fre-\nquency of precipitation\nobservations reporting\n51\n51\nAUGUST\n15\nsnow. (Adapted from\n<15\n<15\nBrower et al. 1977.)\n170\n165\n160\n175\n180\n175","Meteorology, Sea Conditions, & Sea Ice\n21\n165\n170°\n175*\n180\n175\n170\n165\n160\n155\n150\n63\n63\n61\n61\n59\n59\n57\n57\n10\n55\n55'\n5\n53\n53\nFEBRUARY\n51\n51\n175°\n180\n175\n170\n165\n160\n165\n170\n175\n180°\n175°\n170\n165\n160\n155\n150\nla\n63\n63\"\n61\n61\n59\n59\"\n17\n30\n57\n57\n5\n35\n55\n55\n53\n531\nFIGURE 3.4-Percent - fre-\nquency of occurrence of\nall fog during February\nAUGUST\n51\n51\nand August. (Adapted\n165\n160\nfrom Brower et al. 1977.)\n175\n170\n175\n180","22\ngrin Busin Synthesis\nYou\nLegend\nDirection frequency (top scale): Bars represent percent\n10 20 30 40 50 so 70 00 90 100\n0\nindicates < 0.5%\n+\nfrequency of winds observed from each direction.\nH\nbut 0.\nSpeed frequency (bottom scale): Printed figures repre-\nMI\nsent percent frequency of wind speeds observed from\nE\n(1% of all winds were\neach direction.\nSE\nfrom the S with a speed\n$\n(4% of all winds were\nof 22-27 knots.)\nSW\nfrom the N.)\nThe scalar mean speed\nNW\n1240\nwas 9.4 knots.\n(1% of winds from all\nCALM\n12\n29\n22\n1)\ndirections had wind\nTOTAL\n7 11 17 22 28 34\n0\n4\nspeed 48 knots.)\nWIND SPEED (KHOTS)\nNumber of observations.\nIndex map\n150°\n160' o\n170°\n180\no\n5\nSeward Peninsula\nGulf of\nAnadyr\nNorton Sound\nSt. Lawrence I.\n60\n60\nA\nNunivak I.\nBristol Bay\nSt. Paul I.\nAlaska Peninsula\n55\n55\nSt. George I.\nB\n160\n170°\n180\nO\nFIGURE 3.5-Wind speed and direction histograms for Marine Areas A and B. (Adapted from Brower et al. 1977.)","Meteorology, Sea Conditions, & Sea Ice\n23\nJanuary\nMarine Area A\nMarine Area B\n%\n%\n0 10 20 30 40 50 60 70 80 90100\n0 10 20 30 40 50 60 70 80 90100\n1\nN\n113311\nIS\n+\nN\n++11\nNE\n122\nNE\n1133431\n113331\nE\nE\n126856421\n24542\nSE\nSE\n1226532\n24432\nS\nS\n1221\n112\nSW\nSW\n1122\n1::::1\nW\nW\n1221+\n+1++\nNW\nNW\n2\n18.8\n3466\n5\n17.6 472\nCALM\nCALM\n35122223171051\nTOTALS\n861323:17:15125:1\nTOTALS\n4 7111722 28 344148\n047111722 28 344148+\nWIND SPEED (KNOTS)\nWIND SPEED (KNOTS)\nFebruary\nMarine Area A\nMarine Area B\n%\n0102030 40 50 60 70 80 90100\n%\n1 2 178534\n010203040 50 60 70 80 90100\nN\nE1366421\n26742\nN\nNE\n13876421\n25442\nNE\nE\n12333\n1232111\nE\nSE\n:11111\nSE\n1311.\nS\n111:+\nS\n11++\nSW\n:1:1:1\nSW\n2121+\n112211\nW\nW\n111111\n131\nNW\nNW\n17.3 427\n4\n2\n19.3 3271\nCALM\nCALM\n5 51225251782\n2.41125231711521\nTOTALS\nTOTALS\n04 7:111722 28 344148\n04 7111722 28 344148\nWIND SPEED (KNOTS)\nWIND SPEED (KNOTS)\nMarch\nMarine Area A\nMarine Area B\n%\n01020 30 40 50 60 70 8090100\n%\n01020 30 40 50 60 70 80 90100\n+ 4441\nN\n+ 2 354421\n344211\nN\nNE\n23331.\n+\n1\n322411\nNE\nE\n24422\nE\n4533\nSE\n2321.\nSE\n12322.\nS\n112111\nS\n2212\nSW\n11221\nSW\n13111\nW\n1.121\nW\n2421.+\n13321\nNW\nNW\n12.2 449\n6\n4\n16.7 3472\nCALM\nCALM\n918242314822\n595242014931\nTOTALS\nTOTALS\n4711172228 34 4148.\n0\n4 7111722 28 34 4148\nWIND SPEED KNOTS\nWIND SPEED (KNOTS)","24\nNararin Basin Synthesis\nApril\nMarine Area A\nMarine Area B\n0 020 3040 5C 60 70 80 90100\n%\n2412\n0 10 20 3040 50 50 70 80 90100\nN\n4\n:\n35221\nNE\nN\n3521\nNE\nE\n232211\n12\nE\nSE\n223211\n21121\nSE\nS\n122211:\n1212\nS\nSW\n11221\nSW\n:41111\nh\n12332\nW\n121244\nNW\n3532\nNW\n10.0\n157\nCALM\n3\n15.3 2455\nCALM\n117133620562\nTOTALS\n571727191374\nTOTALS\n04711172228 344148.\n4 7111722 28 344148\nWIND SPEED (KNOTS)\nWIND SPEED IKNOTS!\nMay\nMarine Area A\nMarine Area B\n0 1020 30 40 50 60 70 80 90100\n2 I 4 6 2 3\n0 10 20 30 40 50 60 70 80 90100\nN\n13 56211\n24532\nNE\nN\n21 67111\n235321-\nNE\nE\n23531\n11121\nE\nSE\n123211\nSE\nS\n123111\nS\nSW\n12221.\nSW\n2\n423\nW\n12321.\nW\n2\n5221.\nNW\n13422)\nNW\n3\n11.6 269\nCALM\n2\n14.2 1807\nCALM\n151720279731\nTOTALS\n502229181041.\nTOTALS\n047111722 28 34 4148\n04 71117 22 28 34 4148.\nWIND SPEED IKNOTSI\nWIND SPEED (KNOTS)\nJune\nMarine Area A\nMarine Area B\n%\n0 10 20 30 40 50 60 70 80 90100\n%\n212211\n01020304050 60 70 80 90100\nN\n1\n13421\n12442+\nNE\nN\n44421\n1\n2232.1\nNE\nE\n4421+\n222211\nE\nSE\n13321\n3431.\nSE\nS\n13311\nS\n3441.\nSW\n1321.1\nSW\n23421\nW\n1332\nW\n23411\nNW\n23621\nNW\n9\n10.9 451\nCALM\n12.2 2640\nCALM\nTOTALS\n141722261352\n911272915721\nTOTALS\n4 7111722 28 34 4148\n4 7111722 28 34 4148\nWIND SPEED IKNOTS!\nWIND SPEED (KNOTS)","Meteorology, Sea Conditions, & Sea Ice\n25\nJuly\nMarine Area A\nMarine Area B\n%\n%\n110203040 50 60 70 80 90100\n0\n10 20 30 40 50 60 70 80 90100\n11332\n11231\nN\nN\n122\n2221\nNE\nNE\n23311\n1222+\nE\nE\n23311\n13431\nSE\nSE\n34541\n124511\nS\nS\n234311\n1133532\nSW\nSW\n24411\n1124531\nW\nW\n23211.\n13411+\nNW\nNW\n5\n11.6 1682\n4\n12.3 2761\nCALM\nCALM\n1214242813521\nTOTALS\n913232916721\nTOTALS\n04711172228 34 4148\n04 7111722 28 344148+\nWIND SPEED IKNOTS\nWIND SPEED (KNOTS)\nAugust\nMarine Area A\nMarine Area B\n%\n0 10 203040 50 60 70 809010\n010203040 50 60 70 80 90100\n23422\n12421\nN\nN\n23311\n1222\nNE\nNE\n13421\n12321\nE\nE\n2322\n124221.\nSE\nSE\n2232\n36421\nS\nS\n23432\n24331.\nSW\nSW\n233.\n3431\nW\nW\n1232\n3432-\nNW\nNW\n12.4 1754\n15.5 2149\nCALM\nCALM\nTOTALS :0142325493\n391832251\nTOTALS\n04 11722 28 344148\n04 7111722 28 344148\nWINC SPEED IKNO'S\nWIND SPEED IKNOTS\nSeptember\nMarine Area A\nMarine Area B\n%\n010 203040 50 60 70 809010C\n0102030 40 50 60 70 80 90100\n236542\n354311\nN\nN\n3532\n222211\nNE\nNE\n2331\nE\nE\n1342\nSE\nSE\n123\n2222\nS\nS\n222\n12321\nSw\nSw\n1242:\n-\nn\n25431\nNo\n1232\n16.1 2346\nCA\nCAL\nTOTALS\n19 34 41484","26\nNavarin Basin Synthesis\nOctober\nMarine Area A\nMarine Area B\n00203040 50 60 70 80 90100\n0 10 20 30 40 50 6070 80 90100\n3 5 8 5 3 2\n2\n3\n3\n4\n2\nN\nN\n33221\n1221\nNE\nNE\n44211\n122111\nE\nE\n1222\n22221\nSE\nSE\n11221\n1222\nS\nS\n11222\n13342\nSW\nSW\n332\n145,42\nW\n-\n3231\n24443\nNW\nNW\n2\n17.9\n259\n20.6 1020\nCALM\nCALM\n36424235 771\nTOTALS\n22921222237\nTOTALS\n04711172228344148\n047111722 28 34 4148\nWIND SPEED IKNOTS\nWIND SPEED IKNOTS\nNovember\nMarine Area A\nMarine Area B\n%\n%\n0 1020 30 40 50 60 70 80 90100\n0 1020 30 40 50 60 70 80 90100\n2 2 2958\n2\n2\n3\nN\nN\n5\n1334211\nNE\nNE\n345312\n24332-\nE\nE\n2221.\nSE\nSE\n| . .\nS\nS\n112211\nSW\nSW\n1123321\nW\nW\n133431.\nNW\nNW\n21.9 165\n20.1 976\nCALM\nCALM\n25512222621231\nTOTALS\n25112120912721\nTOTALS\n04 7111722 28 344148\n047111722 28 34 4148\nWIND SPEED IKNOIS\nWIND SPEED IKNOTS\nDecember\nMarine Area A\nMarine Area B\n%\n%\n0 1020 30 40 50 50 70 800100\n0 10203040 50 60 70 80 90100\n143421\n123321\nN\nN\n45432\n24341:1\nNE\nNE\n35421\n25531\nE\nE\n653++\n24311\nSE\nSE\n:142.1\n1232..\nS\nS\n2 + 3 . 1\n22111\nSW\nSW\n1.3.3\n1221211..\nW\nW\n+1221.\n123322\nNW\nNW\n4\n14.7 274\n2\n17.9 1729\nCALM\nCALM\n682027221151\nTOTALS\n365252215941\nTOTALS\n4 7111722 28 344148\n047111722 28 34 4148\nn IND SPEED (KNOTS)\nWIND SPEED (KNOTS)","Meteorology, Sea Conditions, & Sea Ice\n27\n165\n170°\n175\n180\n175\n170\n165\n160°\n155\n150°\n63\n63°\n611\n61°\n12\n59\n59°\n20\n12\n57\n57°\n22\n55\n55\n20\n53\n53\nFEBRUARY\n51\n51\n200\n175\n180\n175\n170\n165°\n160\n165\n170\n175\n180°\n175\n170°\n165\n160\n155\n150\n63\n63\n>14\n61\n61\n59\n59\n10\n57\n57\n16\n55\n55\n53\n53\nFIGURE 3.6-Scalar mean\nwind speeds (knots) dur-\ning February and August.\nAUGUST\n51\n51\n(Adapted from Brower et\nal. 1977.)\n175\nPO\n175\n170\n165\n160","thesis\n28\nNavarin Basii\n171°\nYears\n160°\n65°\n65°\nA\n58/59\n180°\n170°\n65/66\n66/67\n77/78\n10\n78/79\n10\n20\n60\no\n60\n30\n20\n30\n40\n55°\n55\no\n50\n40\n60\n50\n70\n51\nO\n51\n70\n171\no\n160°\n180°\n170°\n171°\nYears\n160°\n65°\n65\nO\nB\n58/59\n180°\n170°\n65/66\n66/67\n77/78\n20\n78/79\n20\n30\n60°\n60\no\n40\n30\n50\n35\n60\n55°\n40\n55\nO\nFIGURE 3.7-Storm - track\ncounts for October-Febru-\nary in the five heaviest\n50\n73\nand five lightest ice years\n60\nin 23 winters, 1957-80. A,\n50\n50\n51\nO\n51\nO\nheaviest ice years; B,\nlightest ice years. (Adap-\n171\n160°\no\nted from Pease et al.\n180°\n170°\n1982.)","Meteorology, Sea Conditions, & Sea Ice\n29\nFebruary\nMay\nAugust\nNovember\n50\n50\n50\n50\n40\n40\n40\n40\n30\n30\n30\n30\n20\n20\n20\n20\n10\n10\n10\n10\n4-6\n0-1\n1-2\n2-3\n3-4\n4-6\n0-1\n1-2\n2-3\n3-4\n4-6\n0-1\n1-2\n2-3\n3-4\n4-6\n0-1\n1-2\n2-3\n3-4\nWave Height, m\nFIGURE 3.8-Percent frequency of occurrence of waves for Marine Area B. (Refer to Fig. 3.5 for index to area.\nData source: Brower et al. 1977.)\nSea. Recently Kozo (1983c) prepared an analysis\nstationary structures also poses dangers. It can\nof icing potential in the region. The following\nelevate the structure's center of gravity, cause\nunbalanced weight distribution, alter structural\nparagraphs summarize that analysis.\nFreezing spray is the most common and danger-\nresponses to external loading (as from waves), and\nous manifestation of superstructure icing. It results\nweaken structural members through pressures\nin accumulation of glaze ice of high density and\nexerted by water freezing in confined spaces.\nThe development of freezing spray results from\ngreat adhesion power. Icing effects are most pro-\nnounced on smaller vessels due to their lower\nthe concurrent action of several processes.\nfreeboards and often longer transit times through\nBecause atmospheric conditions generally change\nareas where icing is underway. Vessel icing is\nmore rapidly than oceanic conditions, they appear\nto be the most important variables in ice produc-\ndangerous because it increases weight, changes\ntion. Air temperature is important. The critical\ntrim, elevates the center of gravity, lowers meta-\nrange in the Bering Sea is - 18 to 0°C. Winds are\ncentric height, increases sail area, and increases\nnecessary to generate waves and associated sea\nheeling moment (Berry et al. 1975). Superstruc-\nspray, and ice accumulation is directly propor-\nture icing of oil production platforms and other\nTABLE 3.1 -Predicted frequency of significant wave heights for waves coming from eight directions in February.\nWave Height in Meters\n%\n7\n8\n9\n10\n11\n12\n13\nTotal\nDirection\n1\n2\n3\n4\n5\n6\n35.7\n8\n6\n5\n1\n0\n0\n0\n204\nNorth\n38\n19\n20\n69\n19\n19\n24.7\n7\n5\n0\n1\n0\n0\n0\n141\nNortheast\n23\n6\n18\n25\n37\n19\n10.2\n5\n2\n1\n0\n0\n1\n2\n2\n0\n0\n2\n58\nEast\n34\n9\n57\n10.0\n0\n5\n5\n0\n0\n0\n0\n0\nSoutheast\n22\n12\n6\n4\n3\n=\n31\n5.4\n0\n0\n0\n0\n0\n0\n0\n0\nSouth\n15\n7\n4\n4\n1\n19\n3.3\n0\n0\n0\n0\n0\n0\n0\n0\nSouthwest\n15\n1\n3\n0\n0\n0\n0\n0\n0\n23\n4.0\n0\n0\n0\n0\nWest\n17\n4\n2\n0\n0\n0\n0\n()\n0\n38\n6.7\n0\n0\n0\n0\nNorthwest\n23\n7\n4\n3\n1\n571\n38\n20\n17\n7\n4\n()\n0\n2\nTotal\n187\n65\n62\n107\n62\n3.5\n3.9\n0.4\n0.4\n0\n0\n0.4\n%\n32.8\n11.4\n10.9\n18.7\n10.9\n6.7\nNOTE: Data were derived from 3-hourly wind velocity measurements.\nSOURCE for Tables 3.1-3.4: Kozo 1983a.","Navarin Basin Synthesis\n30\n1/5\n63\n61\n10\n59\n15\n20\n25\n30\n57\n55\n55\n53\n53\nFEBRUARY\n51\n160\n165\n170\n175\n180\n175\n155\n150\n170\n165\n160°\n175°\n175\n180\n165\n170\n&\n63\"\n63\n61\n61\n5\n59\n59\n57\n55\n55\n10\nFIGURE 3.9-Percent - fre-\n53\n53\nquency of occurrence of\nhazardous wave condi-\n(2/200-\ntions during February and\nAUGUST\n51°\n51\nAugust. (Adapted from\n165\n160\n175\n170°\nBrower et al. 1977.)\n175\n180","Meteorology, Sea Conditions, & Sea Ice\n31\ntional to wind speed; the threshold value for spray\nMay through September. However, from Decem-\nformation is about 12.5 m/s. In the Bering Sea\nber through April moderate icing conditions per-\nicing most likely would occur at wind speeds of\nsist long enough to easily allow dangerous 10 cm\n12.5-30 m/s. Sea surface temperature is crucial\nice accumulations. Given no change in the other\nto the development of icing conditions. Water\nvariables, an increase of 5 m/s in wind speed could\ntemperatures of -2.2°C (the freezing point) to\nproduce heavy icing conditions. In April, presence\n8.9°C are suitable, although the upper value is not\nof ice cover over much of the Navarin Basin\nabsolute because spray can freeze rapidly if air\nreduces by more than 50% the area in which icing\ntemperatures are below - 2.2°C. Sea ice coverage\ncan occur (Fig. 3.10).\ninfluences icing conditions; 50% coverage reduces\nThe.extreme analysis showed that icing is possi-\nthe potential for icing to nil due to damping of\nble in the Navarin Basin from September through\nwave action and spray formation.\nJune. The most extreme icing rates are produced\nA 10-cm accumulation of freezing spray on\nin September-February by a combination of mini-\nsuperstructures is considered to be dangerous\nmum air and water temperatures and maximum\n(Berry et al. 1975). Accumulation depends on ac-\npack ice extent (see Fig. 3.11). During March-May\ncretion rate and exposure time, thus these are the\nthe maximum possible extent of ice coverage\nkey factors in assessment of the hazard. Kozo\nprohibits occurrence of much spray-induced icing.\n(1983c) has developed monthly icing potential\nInstead, the most extreme icing then occurs under\nmaps for the Bering Sea. Mean and extreme icing\nconditions of minimal ice extent.\nconditions are forecast based on mean and ex-\ntreme values of air and water temperatures and\n3.6 SEA ICE DISTRIBUTION\n50% sea ice coverage used in combination with\nwind speeds of 14 or 25 m/s. The lower wind\nThe distribution of sea ice changes greatly\nspeed represents the mean condition while the\nthroughout the year. In summer, the entire Ber-\nhigher speed represents extreme storm winds\ning Sea is free of ice. In October and November,\noccurring during passage of cyclones through the\nice forms in situ along the coasts in the northern\nregion. Icing rates were calculated from a nomo-\nBering Sea. Predominantly northeasterly winds\ngram developed by Wise and Komiskey (1980).\ndrive this ice toward the southwest, creating\nFive categories were used to represent differing\npolynyas along the southern sides of peninsulas,\nicing rates.\nSt. Lawrence Island, and St. Matthew Island.\nA number of features of icing conditions in the\nPolynyas are dynamic features. During periods of\nNavarin Basin were revealed by the analysis.\nsoutherly winds, for example, the polynya at St.\nUnder mean conditions icing does not occur from\nMatthew has been observed to shift to the north-\nTABLE -Predicted frequency of peak wave periods for waves coming from eight\ndirections in February.\nPeak Wave Period in Seconds\nDirection\n2\n14\n16\nTotal\n%\n4\n6\n8\n10\n12\nNorth\n6\n16\n35\n89\n38\n19\n1\n0\n204\n35.7\nNortheast\n4\n9\n16\n43\n56\n12\n1\n0\n144\n24.7\nEast\n5\n16\n22\n5\n3\n1\n4\n2\n58\n10.2\n=\nSoutheast\n6\n8\n20\n10\n3\n10\n0\n0\n57\n10.0\n=\nSouth\n3\n4\n15\n8\n1\n0\n0\n0\n31\n5.4\n19\n3.3\nSouthwest\n5\n4\n6\n4\n0\n0\n()\n0\nWest\n5\n4\n12\n2\n()\n()\n0\n0\n23\n4.0\nNorthwest\n6\n8\n16\n7\n1\n0\n()\n()\n38\n6.7\nTotal\n40\n69\n142\n168\n102\n42\n6\n2\n571\n7.0\n12.1\n24.9\n29.4\n17.9\n7.4\n1.1\n0.4","32\nNavarin Basin Synthesis\n180°\n170°\n160°\n65\nO\n65\n60\nO\n60\n55\no\n55\nICING CATEGORIES\nName\nRate (cm)/3 h\nHeavy\n1.03-1.54\nModerate\n0.51-1.03\n000\nLight\n0.20-0.51\n50\n50\n1801\n170°\n160°\nFIGURE 3.10-April mean icing conditions: 50% probability of 50% ice coverage (heavy black line), mean air\ntemperature, and ocean surface temperature corresponding to ice coverage. Under these mean conditions, a 28-knot\n(14 m/s) wind speed (gale level) is imposed. (Adapted from Kozo 1983c.)\nern side of the island (Burns et al. 1981a). Polynyas\nto the cold, off-ice winds and the addition of\nact as production sites for new ice during most\nmeltwater cool the ocean, so that the pack extent\nof the winter (Fay 1974; Muench and Ahlnäs 1976;\nadvances (Pease 1980).\nMcNutt 1981a, 1981b). The floes along the leading\nOn the average, by December the Gulf of\nedge of the pack ice are advected into water that\nAnadyr is covered by ice and the pack ice extends\nis warmer than the freezing point and they melt.\njust south of St. Lawrence Island (C. H. Pease pers.\nThe large, sensible heat flux from the ocean due\ncommun. 1982; see also Fig. 3.12). By January ice","Meteorology, Sea Conditions, & Sea Ice\n33\n180\nO\n170\n160\nO\n65\nO\n65°\n60\n60\n55\n55\nICING CATEGORIES\nName\nRate (cm)/3 h\nExtreme\n2.56+\nVery heavy 1.54-2.56\nHeavy\n1.03-1.54\n50\nO\n50\nO\nModerate\n0.51-1.03\nLight\n0.20-0.51\n180°\n170°\n160°\nFIGURE 3.11-November extreme icing conditions: produced by maximum extent of 50% ice coverage (heavy\nblack line). minimum recorded air temperatures, and ocean surface temperatures corresponding to ice coverage.\nA 50-knot (25 m/s) wind speed (storm level) is imposed. (Adapted from Kozo 1983c.)\nreaches the northern Navarin Basin, although it\nforward, one-step-back process. Years of minimal\nis possible for ice to reach the basin in early Dec-\nice extent are characterized by a predominance\nember. In succeeding months, through March, the\nof storms penetrating the western Bering Sea,\nice edge advances at a rate averaging 150-200\nwhereas years of maximum ice extent are charac-\nkm/mo. This process is not steady, however. Each\nterized by more storms trending east along the\ncyclone that penetrates the region causes a tem-\nAleutians and across the southeast Bering Sea or\nnorthwest Gulf of Alaska (Overland and Pease\nporary retreat. so the advance is a two-steps-","34\nNavarin Basin Synthesis\n1982; Pease et al. 1982). Meteorological steering\nregion may not be clear of ice until July (Webster\nof storms is thus the principal factor causing the\n1981). Usually by the end of June the entire Bering\ninterannual variability of sea ice extent.\nSea is ice free.\nIn April the ice in the Navarin Basin begins to\nIndividual drift rates ranging from about 8 cm/s\nretreat and decay. The region is usually clear of\n(Newton 1982) to 65 cm/s (Martin et al. 1983) have\nice by mid-June, although in a heavy ice year the\nbeen estimated for floes in the vicinity of the\nTABLE 3-Predicted frequency of significant wave heights for waves coming from eight directions in November.\nWave Height in Meters\nDirection\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n11\n12\n13\nTotal\n%\nNorth\n83\n41\n59\n33\n10\n4\n1\n0\n0\n0\n0\n0\n0\n231\n32.4\nNortheast\n29\n25\n28\n16\n15\n25\n0\n14\n7\n3\n1\n0\n0\n163\n22,9\nEast\n16\n9\n21\n17\n16\n0\n14\n8\n4\n0\n2\n1\n1\n109\n15.3\nSoutheast\n9\n7\n9\n6\n4\n0\n3\n1\n0\n0\n0\n0\n0\n39\n5.5\nSouth\n17\n9\n9\n2\n1\n0\n0\n0\n0\n0\n0\n0\n0\n38\n5.3\nSouthwest\n10\n4\n1\n0\n0\n0\n0\n0\n0\n0\n0\n0\n0\n15\n2.1\nWest\n23\n6\n2\n0\n0\n0\n0\n0\n0\n0\n0\n0\n0\n31\n4.4\nNorthwest\n69\n8\n8\n1\n0\n0\n0\n0\n0\n0\n0\n0\n0\n86\n12.1\nTotal\n256\n109\n137\n75\n46\n29\n18\n23\n11\n3\n3\n1\n1\n712\n%\n36.0\n15.3\n19.2\n10.5\n6.5\n4.1\n2.5\n3.2\n1.5\n0.4\n0.4\n0.1\n0.1\nNavarin Basin. Other estimates based on winter\net al. 1983). The MIZ of the Bering Sea has been\nsatellite imagery (McNutt 1981a) and on spring ice\ndescribed by Martin and Bauer (1981) as compris-\nbuoy experiments (Thomas and Pritchard 1981)\ning three types of sea ice (Fig. 3.13). Closest to the\nsuggest mean drifts of around 25 cm/s.\nopen water and extending in a 5- to 10-km-wide\nband is the edge zone, characterized by small floes\n3.7 MARGINAL ICE ZONE (MIZ)\nless than 20 m in diameter. Next is the transition\nzone extending 5 km or more, where floes are\nMarginal ice zones are regions where temperate\nsomewhat larger. Interior to the edge and transi-\nand polar climate systems interact (Johannessen\ntion zones is a region of large floes constituting\nTABLE .4-Predicted frequency of peak wave periods for waves coming from eight\ndirections in November.\nPeak Wave Period in Seconds\nDirection\n2\n4\n6\n8\n10\n12\n14\n16\nTotal\n%\nNorth\n15\n18\n91\n92\n14\n1\n0\n0\n231\n32.4\nNortheast\n11\n6\n47\n44\n40\n21\n4\n0\n163\n22.9\nEast\n1\n4\n20\n21\n33\n22\n7\n1\n109\n15.3\nSoutheast\n1\n2\n13\n15\n4\n4\n0\n0\n39\n5.5\nSouth\n0\n6\n20\n11\n1\n0\n0\n0\n38\n5.3\nSouthwest\n1\n7\n2\n5\n0\n0\n0\n0\n15\n2.1\nWest\n1\n9\n19\n2\n0\n0\n0\n0\n31\n4.4\nNorthwest\n22\n29\n26\n9\n0\n0\n0\n0\n86\n12.1\nTotal\n42\n81\n238\n199\n92\n48\n11\n1\n712\n%\n5.9\n11.4\n33.4\n28.0\n12.9\n6.7\n1.5\n0.1","Meteorology, Sea Conditions, & Sea Ice\n35\n175°\n180°\n175°\n170°\n165°\n160°\n155 O\n65\n65\n1 Nov.\n1 Jan.\n1 Dec.\n60\n1 Feb.\n60\n1 Mar.\n50\n50°\nFIGURE 3.12-Average\nice extent (50% probabili-\nty) during fall and winter.\n180 O\n175°\n170°\n165 O\n160 O\n(Adapted from Webster\n1981.)\nthe major portion of the pack ice. Although the\nmarginal zone, wind waves form, absorbing\nfloes are larger than in the transition zone, the\nenergy from the wind. This wave energy is im-\nbulk of the pack ice drifts freely, with little or no\nparted to the ice floes as radiation stress, causing\ntransmittal of ice stresses. The formation and\nthe ice to be pushed southwest by not only the\ndistribution of these zones are controlled by winds\ndirect wind stress but also indirectly by the wind\nand swell. Swell can propagate into the ice pack\nstress on the water upwind of the floes. During\nfor tens of kilometers (Squire and Moore 1980),\na period of off-ice winds and advancing ice con-\nfracturing the ice into smaller floes and losing\nditions in 1981, Martin et al. (1983) observed 30%\nenergy in the process.\nhigher ice velocities at the ice edge than did Pease\nWhen winds blow from the northeast, the\net al. (1982) for ice floes 80 km toward the interior\nfractured floes travel faster than the intact ice\nof the pack. For various reasons, not fully\nsheet. causing open water to form between widely\nunderstood, the separated floes in the marginal\nspaced bands of ice and the interior pack (Martin\nzone maintain a linear alignment as they drift\nand Bauer 1981: Martin et al. 1983). As open water\naway faster than the close ice behind them. It is\nappears between the pack ice and any part of the\nhypothesized that internal waves supported by the","36\nNavarin Basin Synthesis\nTRANSITION\nEDGE ZONE\nZONE\nINTERIOR ZONE\n5-10 km\n5 km\n- 100 km\n-\nSmall\nSmall\nRectangular\nOpen Water\nBroken Floes\nFloes\nLarge Floes\nFIGURE 3.13-Terminology for sea ice types and areal distribution in the marginal ice zone. (Adapted from\nMartin and Bauer 1981.)\nFloe\nFloe Station 3600. 16-31 May 1981 (Julian days 136-151)\nVelocity\nMean =\n0.17\n1 m/s\n=\ntoward\n260\n0.15\n180\n0.10\n0\n0.05\n138\n140\n142\n144\n146\n0.00\n-180\n136\n138\n140\n142\n144\n146\nMean =\na =\nMean =\n0 =\n0.0297\n0.0145\n59.9\n37.1\n63.0 N.\n176.0 W\n10 m/s =\n136\n138\n137\n139\n144\n140\n141\n143\nFIGURE 3.14 - Relation-\n142\nship between wind speed\nand ice motion with the\ntrajectory of ice and su-\nperimposed wind vectors.\nNumbers along trajectory\nindicate Julian day of ob-\nserved position. (Adapted\n61.5 N.\n179.0 W\nfrom Overland 1983.)","Meteorology, Sea Conditions, & Sea Ice\n37\n178°\n174°\n170°\n166°\n162°\n67°\n67\no\n66\n66\nO\n65\nO\n65\nO\n64\nO\n64\nO\n40\n20\n63\n63\nO\n140\n120\n60\n62\n62\n100\n80\n61\nO\n61\nO\n60 O\n60\nO\n178°\n174°\n170°\n166\n162°\nFIGURE 3.15-Trajectory of Buoy 3600 from 18 January to 23 May 1982 (Julian days 18 to 143). Daily positions\nat 0000 h GMT are marked with dots, and Julian days at 20-d intervals are identified. (Adapted from Thomas\nand Pritchard 1981.)\nsharp pycnocline cause the ice bands to maintain\nwater from the bottom, and allowing the ice to\ntheir linearity (Muench et al. 1983).\nmove more rapidly in response to wind stress.\nOne may expect higher speeds for ice in the\nThe behavior of ice floes near the ice edge has\nmarginal ice zone than in the pack farther north-\nimplications important to an accurate description\neast because the MIZ usually resides over a layered\nof oil spill behavior. Because ice floes in the MIZ\nwater column (see Section 4.1). The pycnocline\nmove faster than the water in which they rest,\nimpedes momentum transfer to the lower water\nthey will out-distance oil introduced in situ or\ncolumn. thereby uncoupling the ice and surface\ncarried there in association with the ice.","Navarin Basin Synthesis\n38\n166°\n162°\n174°\n170°\n178°\n140\n67\nO\n67°\n66\no\n66\no\n120\n65\no\n65\nO\n160\n64\no\n64\nO\n100\n63\n63\n80\n62\n62°\n61\no\n61\no\n60\nO\n60\no\n170°\n162°\n178°\n174°\n166\nFIGURE 3.16-Trajectory of Buoy 3603 from 21 February to 19 June 1981 (Julian days 52 to 169). Daily positions\nat 0000 h GMT are marked with dots, and Julian days at 20-d intervals are identified. (Adapted from Thomas\nand Pritchard 1981.)\nin response to the wind in the MIZ (and elsewhere\nWhen the winds blow toward the ice edge from\nin the pack ice as well) is quite different from the\nopen water, the ice retreats rapidly. The ice is\ndirection in which the winds blow. The floes drift\nreported to have moved 35 km/d during one such\nat an angle of 30-40° to the right of the wind\nevent (J. E. Overland pers. commun. 1982). Dur-\n(Overland 1983) (Fig. 3.14). This is not an unex-\ning periods of on-ice winds, the MIZ becomes\npected result, because it was observed in the Arctic\nnarrower as floes at the edge are driven into the\nOcean by Nansen (1902), elucidated by Ekman\ntight interior pack.\n(1905), and studied by OCSEAP in the Beaufort\nThe observed direction in which ice floes move","Meteorology, Sea Conditions, & Sea Ice\n39\nSea (Thomas and Pritchard 1979). Figures 3.14 and\nficients in air and water and the local latitude,\n3.15 may be compared at the point in the trajec-\nthrough the Coriolis effect. The ratio of drag coef-\ntory marked Julian day 136-140 which occurs in\nficients, which is crucial to accurate modeling of\nthe Navarin Basin. Figure 3.16 is included to show\nice motion, has recently been redetermined near\nthe high variability of ice movement. The present\nthe Navarin Basin by Pease et al. (1983) and\nwork is important because it includes simultaneous\nMacklin (1983).\nmeasurements of wind and water current speed\nThe speed at which ice moves is between 1.5\nand direction and because some of the measure-\nand 5.0% that of the wind in the northern Bering\nments were made in ice which was very likely\nSea (J. E. Overland pers. commun. 1982). These\nunder free drift conditions. Reduced turning angles\nestimates are from preliminary analyses in which\nare found where ice motion is restricted by near-\ncomputed geostrophic winds were compared to\nby fast ice or tight multiyear ice.\nthe motion of satellite-tracked buoys placed in the\nThe turning angle of a drifting ice floe is deter-\nice in 1981.\nmined in large measure by the ratio of drag coef-","","Chapter 4.\nOceanography\nMAURI J. PELTO\nU.S. Department of Commerce, NOAA, National Ocean Service, Office of Oceanography and Marine Services,\nOcean Assessments Division, Alaska Office, Juneau, Alaska\nAND\nROBERT S. PETERSON\nScience Applications, Inc., Boulder, Colorado\n4.1 HYDROGRAPHIC STRUCTURE\nincreases from the sea surface downward. Water\nproperties are relatively invariant year round\nDomains are ocean regions containing uniform\nbelow the pycnocline.\nhydrographic structures; fronts separate the\nThe currents and water masses of the Bering Sea\ndomains. Kinder and Schumacher (1981a) have\nhave been described in general by Takenouti and\ndescribed the hydrographic structure of the\nOhtani (1974). They show how water from the\ncontinental shelf of the eastern Bering Sea. There\nAlaska Stream, a westward-flowing current along\nare no direct observations to show that their class-\nthe south side of the Aleutians, enters the Bering\nification is valid for the Navarin Basin planning\nSea through Amchitka Pass and other passes west\nunit. However, the forces that control circulation\nof Attu Island (Fig. 4.2). This inflow is far greater\nand hydrographic structures are probably similar\nin volume than any other individual source. After\nin the two areas. Based on that rationale, three\nentering the Bering Sea, the Alaska Stream water\ndomains are expected in the Navarin Basin: mid-\nbecomes part of a generally counterclockwise\nshelf, outer shelf, and oceanic (Fig. 4.1). Between\ncirculation pattern, mixing with waters from other\nthe 50- and 100-m isobaths is the midshelf domain.\nsources along the way. More recent studies show\nHere the summer hydrographic structure consists\nthat coastal water derived from the Kenai\nof two layers. The upper layer is both warmer and\ncurrent-not Alaska Stream water-flows through\nfresher than the deeper layer; both layers are well\nUnimak Pass into the Bering Sea (Schumacher and\nmixed. The upper layer is mixed by winds and the\nPearson 1981; Schumacher 1982a).\nlower by tides. The outer shelf domain occupies\nWater is transported northwesterly along the\nthe area between roughly the 100-m isobath and\nnorthern side of the counterclockwise gyre, then\nthe shelf break. It is vertically stratified, having\ndivides in the vicinity of the Navarin Basin. Part\nsurface and bottom layers separated by a weak\nof the flow heads northeasterly to the Bering Strait\npycnocline that is frequently coincident with fine\nand the remainder southwesterly to become the\nstructure in the temperature and salinity profiles.\nEast Kamchatka Current, which ultimately exits\nThe oceanic domain lies seaward of the shelf\nthe Bering Sea. According to Takenouti and\nbreak. This domain is typified by a seasonally\nOhtani's (1974) general description, several quasi-\nvariable surface layer some 100 m thick overlying\npermanent gyres and eddies are present within the\nin summer a temperature minimum that is approx-\nlarger counterclockwise circulation pattern (Fig.\nimately coincident with the top of a permanent\n4.2), but they are not evident in subsequent studies.\npycnocline. Temperature rises with increasing\nOne feature of the general circulatory scheme\ndepth to a maximum value at depths of 200-500\nis a somewhat organized flow along the conti-\nm, then slowly decreases again. Salinity typically\nnental slope, which was named the Bering Slope\n41","42\nNavarin Basin Synthesis\n17C\n175\n180\n175\n62\n59\n59\nCOASTAL\nDOMAIN\nMID-SHELF\nDOMAIN\nOUTER SHELF DOMAIN\n56\n56\nOCEANIC DOMAIN\nFIGURE 4.1 - Hydrograph-\nic domains and fronts on\nthe southeastern Bering\n53\n53\nSea shelf. (Adapted from\nKinder and Schumacher\n180\n175°\n170°\n165\n160\n1981a.)\nCurrent (Kinder et al. 1975). This current may be\nA more detailed circulation pattern during\nbanded and replete with gyres; it has a transport\nsummer has been developed for the Bering and\nof 5 to 10 Sverdrups (Sv) and speeds of 5 to 15 cm/s\nChukchi seas (Liu and Leendertse In press). (See\ntoward the northwest. The bulk of this flow must\nalso Section 4.4.) Surface water movement along\nturn westward off Cape Navarin, but some is\nthe eastern side of the Navarin Basin is to the north\nthought to continue northeastward across the Gulf\nand the flow parallels the continental slope (Fig.\nof Anadyr. The flow, which may induce complex\n4.4). Current speeds are on the order of 5-10 cm/s,\ncirculation within the gulf, then continues eastward\nexclusive of wind-driven contributions. It is\nwhere it is apparently bifurcated by St. Lawrence\npostulated that the subsurface flow to depths of\nIsland. The major transport appears to be through\napproximately 1,500 m also follows this pattern\nAnadyr Strait toward Bering Strait, with a minor\nin areas of deep water (Hughes et al. 1974).\nportion flowing eastward along the southern shore\nKinder and Schumacher (1981b) have analyzed\nof St. Lawrence Island.\nthe circulation over the continental shelf of the\nsoutheastern Bering Sea (Fig. 4.5), using data\nobtained from sites east and south of the Navarin\n4.2 SUMMER CIRCULATION\nBasin planning unit. Over the outer continental\nArsen'ev (1967) calculated surface currents in\nshelf, between the 100-m isobath and the shelf\nbreak (near 170 m depth), mean flow is to the\nJuly (Fig. 4.3) by vectorially adding surface\nnorthwest at 5-10 cm/s. The currents do not\ngeostrophic currents-i.e., those driven by pressure\ngradients and the earth's rotation-and wind drift\nappear to be driven by local meteorological\nforcing. The flow is probably driven by pressure\ncurrents. The geostrophic circulation was a com-\ngradients established by variations in density. Over\nposite of several data sources, and the reference\nsurface of no motion was 1,000 decibars (db).\nthe middle shelf, between the 50- and 100-m","Oceanography 43\n160°\n170°\n180\nO\n170°\n160°\nAnadyr\nGulf\nNorton Sound\nwater\nwater\nIce-forming\narea\n60\n60\nCoastal\nwater\nBering\nSea\nwater\nConvective\narea\nAlaskan\nStream\nWESTERN\nSUBARCTIC\nSTREAM\nALASKAN\nGYRE\n50\n50\nFIGURE 4.2-General\ndescription of circulation\nand water masses in the\nBering Sea. (Adapted from\n160°\n170°\n180°\n170°\n160°\nTakenouti and Ohtani\n1974.)\n175°\no\n175°\n180°\n170°\n63°\n63\n61°\n61\n59\n59\nFIGURE 4.3-Surface cur-\nrent patterns during July\n57\ncomputed from analysis\n57\nof geostrophic currents\nand currents induced by\nwinds. (Data: Arsen'ev\n175°\n180'\n175°\n170°\n1967.)","44\nNavarin Basin Synthesis\n180°\n175°\n170°\n165 O\n160\nU.S.S.R.\nKotzebue Sound\nKolyuchin Bay\nEast Cape\nZaliv Kresta\nPrince\nof Wales\nSEWARD\nPENINSULA\n65\n65\nNome\nCape\nNorton Sound\nNavarin\nSt. Lawrence\n60\n60\nSt. Matthew I.\nBristol Bay\nNunivak\nPribilof Is\n55\n55\nLevel 2\nScale = 10 cm/s per grid length\nUnimak Pass\n180°\n175°\n170°\n165\nO\n160°\nFIGURE 4.4-Residual tidal and baroclinic currents found from a preliminary run of the Rand model. All density\ndata available are not yet in the model, nor have tidal data along the Bering Sea shelf been verified. The effect\nof wind is not included; it is not a significant factor in determining net circulation in most areas due to high variability\nof winds. (Adapted from Liu and Leendertse In press.)\nisobaths, the mean flow is less than 1 cm/s.\nraphy (Kinder and Coachman 1977). Similar bathy-\nHowever, strong tidal currents (> 20 cm/s) occur.\nmetrically controlled perturbations in the flow\nIn a hydrographic survey of Zhemchug Canyon\npresumably occur elsewhere along the shelf break.\nwhere stations were closer together than those of\nTides are probably the major source of energy\nKinder et al. (1975), a meander in the slope current\nfor currents on the shelf as well as on the\nwas revealed by the 50/500 db dynamic topog-\ncontinental slope (Kinder and Schumacher 1981b).","Oceanography\n45\n174°W\n170\nO\n166\nO\n162\no\n158\n62\n62°\n60\n60\n2-4\nO\n2-4\nW\n1-6\n58\n58\n1-6\nW\nW\n1-6\nW\n56\n56\n- 10\n1-10\n5-10\nFrequent eddies\n54\n54\n5-25\n174°W\n170°\n166\n162\n158\nFIGURE 4.5-Estimated mean circulation based on direct observations and inferred geostrophic flow. Values are\naveraged over at least 1 month. Numbers in boxes represent most likely range of mean current in cm/s. There\nis no strong distinction as to season or depth, although the higher speeds are more common in\nwinter\nand/or\nin the upper 20-40 m of the water column. Dashed arrows represent uncertainty or frequent eddies. (Adapted\nfrom Schumacher pers. commun. 1983 to M. J. Pelto.)\nThe semidiarnal component supplies about 80%\nfeature of the Navarin Basin, a semistationary\nof the tidal energy to the inner and middle areas\nhydrographic front is maintained approximately\nof the shelf and 60-70% to the outer shelf. Current\nover the shelf break and approximately parallel\nspeeds and direction vary annually because of\nto it. This front is formed by the melting of ice\nincreased storm activity in the fall, followed by the\ndriven southwestward by the mean flow of winter\npresence :: ice cover.\nair in which there is a slight preponderance of\nnortheasterly winds (Brower et al. 1977; Liu and\n4.3 WINTER CIRCULATION\nLeendertse In press). Melting of ice occurs near\nthe edge of the continental shelf because available\nwinter A hen partial ice cover is a dominant\nheat from relatively warm water is brought up from\nIn","Navarin Basin Synthesis\n46\n83\n82\n80\n78\n76\n74\n72\n71\n70\n69\n0\nIce Covered\n32.25\n32.50\n< 32.12\n50\n33.00\n32.75\n100\n33.25\n150\n30 km\n33.25\nA\n83\n82\n80\n78\n76\n74\n72\n71\n70\n69\n0\nIce covered\n1.0\n- 1.5\n0.5\n0.5\n50\n-1.5\nI\n1.0\n1.0\n-0.5\n2.0\n0\n1.5\n1.0\n100\n0.5\n> 1.0\nFIGURE 4.6-Vertical - dis-\ntribution of temperature\n2.5\n(°C) and salinity (ppt)\nacross the central Bering\n3.0\n150\nSea shelf obtained during\n30 km\n2.5\n30 March-2 April 1980. A,\nB\nsalinity; B, temperature.\n(Adapted from Newton\n1982.)\ndepth by diffusive and advective processes. In\nthe result of a balance between melting rate and\naddition, a deep current along the slope transports\nthe rate at which heat is made available by\nwarmer water from farther south. The ice edge\nbaroclinic currents steered by the salinity gradients\nactually intersects the shelf break at an acute angle\ncaused by the melting. The rate of heat flow is\nmodified also by the strong pycnocline formed\nas described by Muench (1983), who has presented\na model in which the location of the ice edge is\nbelow the melting ice.","Oceanography\n47\n58° N\n- 59°20' N\n1 174° W\nCast Locations\n- 171° W\n0\n32.7\n32.6\n32.5\n32.3\n32.1\n32.6\n32.4\n32.2\n50\n32.8\n32.9\n33.0\n33.1\n100\n33.2\n0\n50\n150\nkm\nFIGURE 1.7-Vertical distribution of salinity (ppt) on 10-11 November 1980 illustrating stratification on the central\nBering Sea shelf prior to ice formation. (Adapted from Muench 1983.)\nThe flux of ice brought down from the northeast,\nnortheastward, some fraction continues eastward\nmelting as it does in the MIZ, supports a two-\nto the south of St. Lawrence Island and results in\nlayered hydrographic structure (Figs. 4.6 and 4.7).\na weak but statistically significant mean flow\nThe effect of this structure on circulation has not\n(approximately 0.035 m/s at mooring NC-25A just\nbeen studied except at the southwesterly edge\nsouth of the island). Farther from the island (at\nwhere the horizontal gradient is at the surface, as\nNC-26A approximately 80 km to the southwest),\ndescribed earlier. The diminished vertical heat\nthe impact of the Gulf of Anadyr circulation is\nflow, because of the two-layered structure, enables\nslight and mean flow insignificant.\nthe ice to survive melting until it reaches the region\nAlthough variations in the wind and regional\nwhere slope currents supply additional heat and\ncirculation accounted for much of the low-fre-\nturbulent energy.\nquency flow south of St. Lawrence Island, there\nWater circulation is along isobaths at depth and\nwere reversals in the NC-25A records during winter\nroughly parallel to the ice edge at the surface.\nwhich suggested that brine rejection created an\nSubsurface current-meter records show overwinter\noffshore pressure gradient which, in concert with\nmean currents of 2-3 cm/s to the northwest, but\noffshore wind stress, reversed the mean flow\nwith frequent reversals. Baroclinic currents at the\n(Schumacher et al. 1983). Scaling of a simplified\nsurface are as high as 7 cm/s, also to the northwest,\nequation of motion indicates that density-induced\nparalleling the ice edge (Muench 1983).\nquasi-geostrophic flow resulting from brine rejec-\nOver the winter of 1980-81, five moorings were\ntion was an important element of the circulation.\ndeployed in the vicinity of the Navarin Basin (Fig.\nThe mean hourly rate of salinity increase, approx-\n4.8). Schumacher et al. (1983) reported results from\nimately 8 X 10-3 g/kg, suggests that about 0.17\nNC-19B, -25A, and -26A. West of St. Lawrence\nm/d of ice was formed during the events. Over this\nIsland there is a strong (approximately 0.15 m/s)\nparticular winter, approximately 5 m of ice were\nmean flow toward Bering Strait. The relatively high\ntherefore produced in the polynya adjacent to St.\nsalinity of this water suggests it is a continuation\nLawrence Island. An estimate of salinization in the\nof the anticyclonic circulation in the Gulf of Anadyr\nnorthern Bering Sea shelf polynyas suggests that\n(Coachman et al. 1975). While the major portion\nthis process is comparable in effect, but opposite\nof outflow from the Gulf of Anadyr is directed\nin phase. to that of runoff and thus an important","Valarin Basin Synthesis\n1789\n176°\n174°\n172°\n170\n168\nO\n166°\n164\nDo\n65\n65\nX\nx\nNC-19B\n64\n64\nX\nNC-26A\nX\n63\n63°\nNC-25A\n62°\n62\n61\n61\nBC-22\n60\n60\nFIGURE 4.8-Current-\n59°\n59°\nBC-21\nmeter mooring locations\nScale 3533516 at lat. 62.000\ncm/s\nand mean flows, winter\nFrom 803220000 to 810950000\n1980-81. Bars at ends of\n0.0\n25.0\n35-hour filter data, N = 557\nvectors indicate variance\nabout the mean. (Adapted\n178°\n176°\n174°\n172°\n170°\n168°\n166°\n164°\nfrom Salo et al. 1983.)\nconditions are well correlated with winds (Salo et\npart of the seasonal salt budget.\nMuench (1983) presented results from BC-26 and\nal. 1983).\n-22 and noted that both geostrophic estimates and\nMuench (1982) summarized winter circulation as\nobserved currents were generally consistent with\nfollows:\na net north-northwestward flow on the central\n1) The central Bering Sea shelf region was char-\nacterized in November 1980 and February-\nBering shelf similar to that depicted on the south-\nMarch 1981 by a water structure vertically two-\neastern shelf by Kinder and Schumacher (1981b).\nlayered in temperature, salinity, and density.\nVariations in current from the means are\nIn November, this structure covered the entire\napparently caused by meteorologic conditions with\nshelf. In February-March, the structure was\nonly certain exceptions, such as cited above, for\nrestricted to a band about 80 km wide which\nquasi-geostrophic flow caused by brine rejection.\nunderlay the ice edge.\n2) Associated with the two-layered structure in\nCurrents appear to be correlated on a distance\nwinter was a northwesterly baroclinic surface\nscale similar to that of mesoscale winds. Winter\ncurrent having maximum speeds of about 7\ncurrents under both ice-covered and ice-free\ncm/s relative to the 75-db level. Northwest-","Oceanography\n49\nLiu and Leendertse 1979, In press). The model pro-\nward baroclinic volume transport relative to\nthe same level was of the order 0.5 X 106 m³/s.\nvides a three-dimensional solution to the complete\n3) Observed overwinter mean currents at two\nequations of motion under long wave conditions,\nlocations on the central Bering Sea shelf at 50\nsubject to the usual boundary conditions, plus the\nm of depth were 2-3 cm/s, with flow along-\neffect of density gradients and stratification. Ice\nisobath to the northwest in agreement with\ncover is included in the model (Liu and Leendertse\nconventional wisdom on Bering shelf circula-\ntion. These mean flow speeds were somewhat\n1981) by a momentum equation for ice coupled\nhigher than those previously reported farther\nto the momentum equations for the water column.\nto the southeast on the shelf.\nAlthough the effect of winds is not included in\n4) Fluctuations, having time scales of 7-10 days,\nFigure 4.4, it is included in the complete model\nwere present in both speed and direction at\nsystem as a stochastically determined driving force\nboth current moorings, and led in several in-\non the surface layer.\nstances to reversals to southeastward flow.\n5) Monthly mean observed currents were all\nThe currents shown in Figure 4.4 are driven by\nalongshelf toward the northwest; however,\ntidal energy and the potential energy of density\ncross-shelf components fluctuated from month\ngradients present under typical summer condi-\nto month with maximum on-shelf flow in mid-\ntions. Note the similarity in direction to earlier\nwinter.\nconceptual models. Tidal residual currents arise\n6) Tidal currents were 20-40 cm/s east of St.\nMatthew Island and 10-30 cm/s west of it.\nin large measure from the nonlinear interaction\nTides were mixed, predominantly diurnal.\nof the tidal wave with a sloping bottom. As the\n7) Overall temperature-salinity characteristics on\ntide propagates over the shelf, harmonics of the\nthe central shelf in both November 1980 and\nconstituents are generated and advective terms in\nFebruary-March 1981 were similar to those of\nthe nonlinear equations are amplified wherever\nAlaska Stream and Bering Sea Water, rather\nthere is a substantial gradient in either bathymetry\nthan to Bering Shelf Water as defined farther\nto the southeast.\nor density. Therefore, the strongest currents occur\n8) A hypothesis is developed which qualitatively\nnear the shelf break (except in straits) where there\ninterrelates the ice edge location and the ob-\nis a rapid change in depth and where there also\nserved temperature, salinity, and current fields\nis a slight increase in the density gradient\nin terms of stability of a baroclinic current\n(Schumacher 1982b).\nwhich is maintained by the ice edge, under-\nice heat advection by near-bottom flow, and\nAs stated earlier, mean winds do not have a great\ncontrol over vertical heat exchange by a den-\neffect on the mean circulation in the Navarin Basin\nsity interface.\nduring summer because they tend to come from\nall directions. At any given time, if the effect of\n4.4 MODEL RESULTS\nwinds were added, the surface circulation shown\nin Fig. 4.4 would not be valid. The effect of winds\nFigure 4.4 shows results obtained recently with\non circulation is discussed further in Section 9.3.\na general circulation model (Leendertse et al. 1973;\nTABLE 1-BC-26 tidal currents. Location, 60°34' N, 176°02' W; total depth, 119 m; meter\ndepth, 50 m; start 1980 Julian day 318, end 1981 day 155.\nAmplitude (cm/s)\nPhase\nOrientation\n°T\nRotation\nConstituent\nMajor\nMinor\n°G\nClockwise\n146 + 5\n318 + 6\n01\n5.4 +0.4\n3.5 + 0.5\nClockwise\n163 + 7\n319 + 7\nK1\n8.2\n+0.3\n6.1 + 0.3\n47 + 13\nClockwise\nN2\n3.4 +0.4\n2.5 +0.4\n102 + 15\nClockwise\n7.9 I 0.4\n154 + 8\n44 +1 5\nM2\n10.4 + 0.3\nSOURCE Mofield 1982\nNOTE: Error estimates are standard deviations (1) Estimates based on 12 overlapping harmonic analyses\n(29-day): one anomalous estimate was rejected because the constituents deviated over 10g from the\nmean","Navarin Basin Synthesis\n50\n240\n42\n343\n300\n240\n300\n240\n180\n0\n180\n199\n300\n60\n150\n58\n240\n113\n180\n346\n167\n120\n300\n240\n103\n180\n80\n90\n96\n83\nFIGURE 4.9-Cophase lines (in degrees relative to the Greenwich transit) for the semidiurnal M2 tidal constituent\nin the Bering Sea, computed using a vertically integrated numerical model. Values in boxes are observed M2\namplitudes. (Adapted from Sündermann 1977.)\ncircular (Kitani and Kawasaki 1979; Mofjeld 1982).\n4.5 TIDES\nTidal excursions, which may cyclically transport\npollutants, are only 5 km even when all constitu-\nAs noted earlier, in the Navarin Basin the tides\nents are in phase.\nare mixed, predominantly semidiurnal. The M2 tide\nAs in the southeastern Bering Sea, most of the\nis the major constituent; it originates in the central\nkinetic energy driving water movements in the\nBering Sea and propagates across the continental\nNavarin Basin is generated by the tides. Bering Sea\nshelf as indicated by the co-phase lines of Figure\ntidal currents generated by the general circulation\n4.9. An inferred amphidromic system in the Gulf\nmodel (Fig. 4.11) have been verified by com-\nof Anadyr (Fig. 4.10) is of interest because it\nparisons with pressure-gauge and current-meter\ninfluences tides in the Navarin Basin, causing the\nrecords from Norton Sound and Bristol Bay.\ncircular tidal residuals seen in Figure 4.11. (The\n(Additional verifications will be possible for the\nAnadyr amphidrome has been predicted by two\nNavarin Basin when data from moorings shown\nmodels, but not yet verified.)\nin Figure 4.12 are available.) Comparisons between\nTidal current constituents in the Navarin Basin\nrecent model and observational results for the\nare weak. They varied from 3 to 10 cm/s at a loca-\nNavarin Basin can be made by reference to Figures\ntion in 100 m of water in the central portion of\n4.11 and 4.13. The first shows the modeled integra-\nthe planning unit (Table 4.1). Slightly higher values\ntion of 12.5 hours of tidal current, considering all\nwere obtained nearby at 200 m; however, moor-\ntidal constituents. The second figure shows tidal\ning motion there may have affected the records.\nellipses derived from mooring data, demonstrating\nAt both moorings the M2 tidal ellipses are nearly","Oceanography\n51\n180°\n170°\n160\nO\nU.S.S.R.\nKotzebue Sound\nEast Cape\nZaliv Kresta\n210°\nPrince of Wales\n65\no\n270°\n65\nNome\nNorton Sound\nCape\n7.\nNavarin\n330°\nSEWARD\n90°\n15 cm\nPENINSULA\n20\ncm\n60\n60\nBristol Bay\n200\n800\n330°\n40 cm\n90°\nPribilof Islands\n270°\n20 cm\n180°\n55\n55\nUnimak Pass\nFIGURE 4.10-Co-tidal -\nchart for the semidiurnal\ntidal component. com-\nwas\nputed using the three-\ndimensional model of Ber-\ning and Chukchi seas.\n180°\n170°\n160 O\n(Adapted from Liu 1981.)\nvery nearly elliptical bottom currents on the order\norganisms in water or sediment samples collected\nof 15 cm/s. The implication is that tidal currents\nfrom the Navarin Basin.\nconstitute a significant source of mixing energy\nKaplan and Venkatesan (1981) found that organic\nsimilar to that available in Bristol Bay. However,\ncarbon concentrations in the sediments of the\nbecause the Navarin Basin is deeper than Bristol\nNavarin Basin are 0.1-1.4%, values which are\nBay, the energy density in the former region is less.\nsimilar to concentrations measured in other areas\nof the Alaskan shelf and are typical of unpolluted\n4.6 CHEMISTRY AND NUTRIENTS\nregions. Gas chromatographic analyses of the sedi-\nments conducted by these investigators suggested\nChemical oceanographic data for the Navarin\nthat the hydrocarbons in the sediments derive\nBasin are limited. However, judging from informa-\nentirely from local and remote biogenic sources.\ntion obtained in other parts of the Bering Sea and\nAbundance of polyolefins indicates input from\nNorton Sound (Shaw 1977; Robertson and Abel\nphytoplankton or zooplankton. In view of the\n1979: Cline 1981; Shaw and Smith 1981), it is\nNavarin Basin's remoteness from terrestrial sources\nprobable that the hydrocarbons and trace metals\nof organic material, the sediments were expected\nnow present in these waters do not derive from\nto have little in the way of terrestrial hydrocarbons.\npetrogenic sources. Evidence supporting this\nHowever, Kaplan and Venkatesan found substantial\nconclusion was presented by Atlas (1981). who\nlevels of terrestrial hydrocarbons as evidenced by\nfound no petroleum hydrocarbon-degrading micro-\nhydrocarbon and n-alkane contents and odd-even","Vatarin Basin Synthesis\n160\nO\n170°\n165\n180°\n175°\nU.S.S.R.\nKotzebue Sound\nKolyuchin Bay\nEast Cape\nZaliv Kresta\nPrince\nSEWARD\nof Wales\nPENINSULA\n65\n65°\nNome\nNorton Sound\nCape Navarin\n60\no\n60°\nBristol Bay\nPribilof\n55\n55°\nUnimak Pass\nTidal Ellipses\nLevel 1\nVect 85.7330\n165\nO\n160°\n175°\n170°\n180\nFIGURE 4.11-Computed 12.5-hour tidal ellipses at 10-m depth. (Adapted from Liu and Leendertse In press.)\nThe outer continental shelf and slope in the\nratios of C15-C34, which are in the same range as\nNavarin Basin appear to be areas of upwelling of\nlevels observed in Norton Sound and the southeast-\nnutrients during summer which foster high\nern Bering Sea. The latter regions may contribute\nphytoplankton production. Handa and Tanoue\nterrestrial lipids to the Navarin Basin.","Oceanography\n53\n178°\n176°\n174°\n172°\n170°\n168°\n166°\nDo\nLD-10\nW\nE\n65\no\n65\nNC-19\n64\n64\n63\n631\nNC-17\n62°\n62\nLD-16\n61\no\n61\n0\nLD-14\nLD-15\nBC-26\n60\n60\n20\n10\nPMEL stations\nsimultaneously recording\n5 Nov. 1981-28 July 1982\nFIGURE 4.12-Locations\n59°\n59\n= PMEL, pressure gauge\nof recently occupied pres-\nPMEL. current meter\n=\nSAI, current meter only\nsure and current stations\nLD-13\nKitani, current meter\n=\nin the northern Bering\nSea. (Adapted from Mof-\n178°\n176°\n174°\n172°\n170°\n168 O\n166°\njeld 1982.)\npycnocline at the top of the cold water mass in-\n(1981) observed values of particulate organic\ncarbon and nitrogen in the region south of St.\nhibits vertical mixing, SO nutrients in the surface\nlayer are depleted during spring. No continuing\nMatthew and Nunivak islands that were some two\nand one-half times those obtained in the North\nsource providing for sustained primary produc-\ntivity exists there, as it does along the shelf edge.\nPacific, North Atlantic, and Indian oceans, and\nInorganic nutrient levels on the continental shelf\nequal to the highest open ocean values-those\npreviously observed off Ecuador. They attributed\nsoutheast of St. Matthew Island during the summer\nthe high values to upwelling of intermediate and\nappear to be very low. During 1975 Handa and\ndeep waters along the continental slope. Evidence\nTanoue (1981) measured SiO2-Si and NO-N levels\nfor upwelling was present in vertical profiles of\nof only 3-10 and 0.1-1.0 ug/liter, respectively.\nAlmost undetectable amounts of NO-N and NH-N\ndensity (of) and dissolved organic carbon across\nwere found in the uppermost 10 m. Near Nunivak\nthe shelf and deep water areas.\nIsland, increased levels of detrital organic carbon\nPoor phytoplankton productivity was observed\nin particulate matter were encountered. The\nin the area between St. Matthew and St. Lawrence\nhigher values were attributed to drainage from\nislands. The low productivity was attributed to the\ncold water mass in the bottom layer there. The\nadjacent land.","54\nNavarin Basin Synthesis\n0\n10 20 (cm/s)\nStation 20\nStation 10\nN\nN\nSurface layer\nSurface layer\n0\n6\n6\n0\nW\nE\nW\nE\n0\n0\n12\nS\nS\nN\nN\nBottom layer\nBottom layer\n8\n12\n8\nW\nE\nW\nE\n0\n0\n0\n12\nS\nS\nStation 61\nStation 68\nN\nN\nSurface layer\nSurface layer\n12\n12\n0\n0\nW\nE\nW\nE\n6\n6\n0\n0\nS\nS\nN\nN\nBottom layer\nBottom layer\nFIGURE 4.13 - Current\n12\nellipses derived from\n12\n0\nmooring data. Semidiur-\n0\nnal ellipses are marked\nW\nE\nW\nE\nwith hour 6 and diurnal\n5\nellipses by hour 12. See\n6\n0\nFigure 4.12 for approx-\n0\nimate station locations.\n(Adapted from Kitani and\nS\nS\nKawasaki 1979.)","Chapter 5.\nLower Trophic Levels\nGEORGE R. TAMM\nScience Applications, Inc., Boulder, Colorado\nAND\nLAURIE E. JARVELA\nU.S. Department of Commerce, NOAA, National Ocean Service, Office of Oceanography and Marine Services,\nOcean Assessments Division, Alaska Office, Juneau, Alaska\nLower trophic level organisms in the Navarin\nby Motoda and Minoda (1974) from data collected\nBasin include bacteria, phytoplankton, zooplank-\nbetween 1956 and 1970 by the Faculty of Fisheries,\nton, and benthos. Their contributions to the pro-\nHokkaido University. Boreal-oceanic diatoms\nductivity of the Navarin Basin are discussed herein.\n(Thalassiothrix longissima, Corethron hystrix,\nDenticula seminae, Nitzschia seriata, and a\n5.1 BACTERIA\nChaetoceros-Phaeoceros group) predominate in\nthe deep basin of the western Bering Sea (Fig. 5.1).\nAtlas (1981) measured microbial populations in\nA Chaetoceros or Hyalochaete group, which\nthe water column and sediments of the Navarin\nincludes C. debilis, C. decipiens, and C. radicans,\nBasin during 1979 and 1980. Direct counts of\nis found along the coasts. The presence of the\norganisms were 0.2-7.7 X 105 in the water col-\nChaetoceros-Phaeoceros group on the eastern\numn and 1.3-6.7 X 109 in the sediments. Viable\nBering Sea shelf is indicative of the cold oceanic\ncounts were 0.1-12 X 103 in the water and 0.1-2.9\nwater in this region.\nX 106 in the sediments. Atlas (1981) stated that,\nThe largest diatom standing stocks have been\nin general, microbial populations are lower in the\nfound in the area north of the central Bering Sea\nNavarin Basin than in the northern Bering Sea.\n(Fig. 5.2). Daily water column productivity rates\nrange from 143 mg C/m² in the Aleutian area to\n630 mg C/m² in Bristol Bay (Motoda and Minoda\n5.2 PHYTOPLANKTON\n1974). The order of importance of areas in terms\nAlexander and Cooney (1979) described\nof phytoplankton productivity is Bristol Bay, the\nphytoplankton communities during late winter and\neastern shelf, the central Bering Sea, and the\nspring in the Bering Sea (including some stations\nAleutian area.\nMcRoy and Goering (1974) found that the an-\nin the Navarin Basin). Two major phytoplankton\ngroups were identified by cluster analysis: an ice\nnual cycle of primary production in the Bering Sea\nedge group characterized by Nitzschia spp.,\nbegins with the development of an algal communi-\nty on the underside of the ice. This is followed by\nAchnanthes, Navicula spp., and other chain-form-\na bloom at the ice front and then the normal spring\ning diatoms; and a shelf break group character-\nized by large numbers of Chaetoceros spp. and\nbloom in the open water. The repontic algae begin\nThalassiosira nordinskioldii, as well as the\nto increase in late February and reach a maximum\npresence of Rhizosolenia alata, Eucampia\njust before the ice disappears. Daily production\nof repontic algae ranges from 2.2 mg C/m² (McRoy\nzoodiacus. and Thalassiosira spp.\nand Goering 1974) to 15 mg C/m2 (Alexander and\nPhytoplankton data for the early to midsummer\nChapman 1981). Extrapolated over 100 days. this\nperiod in the Bering Sea have been summarized\n55","56\nNavarin Basin Synthesis\n160°W\n160°E\n170 °E\n180°\n170°W\n60°N\n60°N\nPhaeoceros &\nChaetoceros-Phaeocero\nThalassiothrix\n50°N\n50°N\nChaetoceros-Hyalochaete\n160°E\n170°E\n180°\n170°W\n160 °W\nFIGURE 5.1-Species composition of diatom communities in the surface layer of the Bering Sea in early to mid-\nsummer. (Adapted from Motoda and Minoda 1974.)\namounts to less than 1% of the annual primary\naround the Bering Strait.\nproduction of the southeastern Bering Sea.\nAlexander and Chapman (1981) have suggested\n5.3 ZOOPLANKTON\nthat the primary contribution of the epontic algae\nis as a source of concentrated food in the early\nZooplankton distributions in the Bering Sea have\nseason at the active ice edge.\nbeen described by Motoda and Minoda (1974) who\nSixty-five percent of the primary production of\nsummarized data collected by the Japanese from\nthe Bering Sea occurs during the spring bloom\n1954 to 1970 (Fig. 5.4). Primarily neritic zoo-\nperiod, with the largest input during May at the\nplankton species are found in the shallow eastern\nice edge (Fig. 5.3). The ice-edge bloom is probably\nportions of the Bering Sea, whereas the arctic\npromoted by the stability associated with the low-\nCalanus glacialis and the arctic-boreal Acartia\ndensity water around the melting ice (McRoy and\nlongiremis are found near the shelf. Subarctic\nGoering 1974). Nutrient measurements seem to\noceanic species are found predominantly in the\nsuggest that this bloom is nitrate limited (Alex-\ncentral and western parts of the Bering Sea. Ap-\nander and Cooney 1979).\nproximately 80% of the zooplankton standing\nThe open-water bloom peaks in late April-early\nstock has been found in the upper 80 m of the\nMay and is associated with the formation of the\nwater column. Zooplankton abundance is higher\nseasonal thermocline. The open-water bloom\nin the Bering Sea in early to midsummer than that\nbegins in southern Bering Sea waters and moves\nin the subarctic water south of the Aleutian Islands.\nnorth with spring. McRoy and Goering (1974)\nThe highest zooplankton numbers in the Bering\nreport that the highest productivity in the Bering\nSea have been recorded around the Pribilof Islands\nSea occurs in the summer in the northern waters\n(Fig. 5.5). The central Bering Sea region tends to","Lower Trophic Levels\n57\n160°W\n170°E\n180°\n170°W\n160°E\n60°N\n107\n60°N\n109\n107\n10\n10\n107\n107\n106\n10\n107\n106\n106\n106\n50°N\n50°N\n108\n170°W\n160 °W\n160°E\n170°E\n180°\nFIGURE 2-Diatom standing crops (cells/m3) in the Bering Sea in early to midsummer. (Adapted from Motoda\nand Minoda 1974.)\nmunity is dominated by large copepods, as in\nbe higher in zooplankton biomass than either the\noceanic waters. The large copepods are relative-\nnorthern shelf region or the area just north of the\nly efficient grazers of the local phytoplankton,\nAleutian Island chain.\nperhaps consuming the equivalent of daily plant\nThe Navarin Basin planning unit extends over\nproduction at times. In contrast, over the middle\nthe deep ocean waters, the continental slope, and\nshelf landward of the front, the zooplankton com-\nthe shelf and would, therefore, be characterized\nmunity consists primarily of smaller copepods\nby a combination of the zooplankton communities\n(mainly A. longiremis, Pseudocalanus spp., and\ndescribed above. The differences in species com-\nOithona similis) that are comparatively inefficient\nposition affect the coupling between utilization of\ngrazers and thus are able to consume only a small\nalgal production and the pelagic herbivores (Alex-\nproportion of plant production. Thus much of the\nander and Cooney 1979; Cooney and Coyle 1982).\nphytoplankton over the middle shelf is ungrazed\nThe open-ocean system, with its large grazing\nand eventually sinks to the sea floor where it\nspecies, appears to be an efficient system, with little\nbecomes available to the benthos.\ncarbon escaping the upper 200 m. Cooney and\nNiebauer et al. (1981) have discussed how ice\nCoyle have described the trophic implications of\ndistributions affect grazing effectiveness in the\nthe cross-shelf differences in copepod communities\nBering Sea. During cold years when the ice edge\nin the southeastern Bering Sea. It seems likely that\nextends over the oceanic water mass, the ice edge\ntheir findings also extend to the Navarin Basin\nzone interacts with a more diverse grazing com-\ngiven the presumed continuity of hydrographic\nmunity and a much greater percentage of the\nstructure northward into the latter region. In brief,\nwater column plant production is utilized directly.\nseaward of the middle shelf front located at\nDuring warmer years, the ice edge occurs farther\napproximately 80 m depth, the zooplankton com-","Nararin Busin Synthesis\n58\n65%\n200\n100\n24%\n8.6%\n1.4%\n1%\nI\n0\nJan\nFeb\nMar\nOct\nApr\nMay\nJun\nJul\nAug\nSep\nNov\nDec\nFIGURE 5.3-Annual distribution of primary production over the southeastern Bering Sea shelf. Bars indicate total\nproduction (g C/m² during various periods; values above bars represent percentages of annual production.\n(Adapted from Alexander and Cooney 1979.)\n160°E\n170°E\n180°\n170°W\n160°W\nEurytemora herdmani\nEpilabidocera amphitrites\nTortanus discaudatus\n60°N\n60°N\nCalanus plumchrus\nCalanus glacialis\nC. cristatus\nAcartia longiremis\nEucalanus bungii bungii\nMetridia pacifica\n50°N\n50°N\nCentropages abdominalis\nMixed community\n0\n160°E\n170°E\n180°\n170°W\n160°W\nFIGURE 5.4-Characteristic copepod communities in the Bering Sea in the upper water layers in early to mid-\nsummer. (Adapted from Motoda and Minoda 1974.)","Lower Trophic Levels\n59\n170°W\n160°W\n160°E\n170 °E\n180°\n23.1\n29.9\n12.5\n(80 m);\n(60 m)\n(30 m)\n40.2\n14.8\n60°N\n60°N\n67.1\n(80 m\n52.4\n37.2\n44.0\n33.0\n31.0\n37.1\n(60 m)\n(50 m)\n36.7\n21.8\n50°N\n50°N\n45.9\n24.15\n28.4\nIS\n22.8\n35.0\n17.7\n19.1\nD\nD\n14.3\n18.0\n20.0\n18.8\n140.1\n170 °W\n160 °W\n160°E\n170°E\n180\nFIGURE 5.5-Average summer zooplankton biomass (wet weight, g/m2) in 80-m water column over a 15-year\nperiod, 1956-70. (Adapted from Motoda and Minoda 1974.)\ntemperatures at the bottom reach 1-2°C, as well\nnorth and interacts with the shelf communities.\nas where the sea floor coincides with the boundary\nA great percentage of the algal production is left\nof the warm intermediate layer. The Subarctic-\nungrazed by the smaller zooplankton.\nBoreal complex dominates on the outer continen-\ntal shelf and continental slope where water depths\n5.4 BENTHOS\nare 150-500 m and temperatures are 2-4°C.\nStoker (1981) found that sediment type is the\nInformation on the benthic invertebrate fauna\nenvironmental variable most directly correlatable\nof the Navarin Basin comes largely from two\nwith the distribution of benthos species over the\nsources: the Russian Bering Sea expedition of\neastern Bering Sea shelf, followed by latitude and\nTirno and Virno in 1958-60 (Neiman 1963), and\nthen longitude. He also noted that, were sufficient\nopportunistic sampling from the U.S. icebreaker\ndata available, summer bottom temperature would\nPolar Star in 1980 (Feder et al. 1981).\nbe strongly correlatable with faunal distributions.\nNeiman (1963) described the zoogeography of\nNeiman (1963) noted that the principal species\nbenthic fauna in the eastern Bering Sea. He iden-\nof these faunal complexes did not differ between\ntified four major faunal complexes, three of which\nthe eastern and western portions of the Bering Sea.\noccur in the Navarin Basin region. Proceeding from\nHe also stated that the faunistic boundary between\neast to west the Navarin Basin fauna are: Pan-\nthe Arctic and North Pacific Boreal regions is\nArctic, Arctic-Boreal, and Subarctic-Boreal. Pan-\nrelatively distinct in the western Bering Sea and\nArctic animals dominate between St. Lawrence and\ndiffuse in the eastern Bering Sea. The faunistic\nSt. Matthew islands, where bottom water tempera-\nboundary passes through the Navarin Basin, ex-\ntures usually are below 0°C year round. Arctic-\ntending southeastward from the Anadyr River\nBoreal benthos are found where summer water","Navarin Basin Synthesis\n60\n160\n170\n180°\nSEWARD PENINSULA\nCHUKCHI PENINSULA\n65\n65\nO\n/\nA\nNome\n2 Chirikov\nN-5\nGulf of Anadyr\n40\nBasin\nN-1\n38\n65\nNorton Sound\nST. LAWRENCE ISLAND\nV\nCape Navarin\nSt. Matthew Basin\n100 m\nLease Area\n26\nB\nE\n25\n24\n27\nD\n20\n23\n19\n21\n31\nBethel\n200m\n22\n14\n60\n18\n17\n60\nO\n5\n15\n4\n16\n9\n13\nNavarin Basin\n3\n12\n50 m\nA\n10\n11\nLease Area\n2\nB\nNUNIVAK ISLAND\n79\n69\nKing\nC\n72\n73\nSalmon\n71\nBristol Bay\nF\n75\n74\nZhemchug Basin\n50 m\n0\nPRIBILOF ISLANDS\nALASKA PENINSULA\nLease Area\n100 m\n55\n55\nO\n200 m\nDutch Harbor\n160\n170°\n180\no\nFIGURE 5.6-Benthos associations based on station groups formed by a cluster analysis of In-transformed density\ndata (number of individuals/m²). (Adapted from Feder et al. 1981.)\nformis was present in highest densities and the\nthrough St. Matthew Island to Nunivak Island.\nseastar Ctenodiscus crispatus was the biomass\nNumerical analyses of grab samples obtained\ndominant. Group B also occurred in water depths\nduring the Polar Sea cruise have provided consid-\nof 100-200 m. The number of species observed\nerable quantitative information on infauna in the\nwas 101, mean density was 1,519 organisms/m²,\nNavarin Basin area. Cluster analyses by Feder and\nand mean biomass 123.8 g/m². The most common\nhis associates revealed three faunal associations\norganisms in Group B were D. craterodmeta, the\n(Fig. 5.6). Group A' was found in depths of 100 to\nclam Axinopsida serricata (which was also the\n200 m. It has 132 species, a mean density of 1,864\nmost dominant species), and H. filiformis. Species\norganisms/m², and mean biomass of 111.2 g/m².\npresent in high densities were D. craterodmeta, A.\nCommon species encountered were the\nserricata, H. filiformis, the polychaete Maldane\npolychaetes Haploscoloplos elongatus and\nglebifex, the ophiuroid Ophiura sarsi, and the\nHeteromastus filiformis, the amphipod Ericthonius\npriapulid worm Priapulus caudatus. Biomasses of\nhunteri, the shrimp Argis lar, the echiuroid worm\nM. glebifex, C. crispatus, and O. sarsi were relative-\nEchiurus echiurus alaskanus, and the brittle star\nly high, with the last named dominant. Group D\nDiamphiodia craterodmeta. Heteromastus fili-","Lower Trophic Levels\n61\noccurred in depths of 81 to 103 m. It comprised\nshelf. In fact, Station Group D had the lowest mean\n48 species. Mean density and biomass were 622\ndensity and second lowest mean biomass of all sta-\norganisms/m² and 94.4 g/m², respectively. The\ntion groups shown in Figure 5.6. Three species\npolychaetes Barantolla americana and Nephthys\nwere dominant in the area encompassed by the\npunctata and the clam Macoma calcera were the\nboundaries of Groups A' and B: H. filiformis, A.\nmost common species in Group D. In terms of\nserricata, and O. sarsi. All three station groupings\nmean density and biomass, B. americana and M.\nconsisted mainly of deposit-feeding organisms.\ncalcera were the dominant organisms present.\nAlthough the southeastern Bering Sea is poor\nThe infaunal benthos associations just described\nin benthic invertebrate biomass in comparison to\nmay not accurately reflect the abundances and\nmore northern regions, it supports a larger ground-\nbiomasses of certain species. As noted by Stoker\nfish biomass than the northern areas. This appar-\n(1981), large deep-burrowing bivalves such as those\nent paradox results from the facts that a relative-\nof the genera Mya and Spisula are not effectively\nly greater portion of the benthos in the southern\ncaptured by grabs and trawls and thus may be\narea is suitable as food for fishes and the benthos\nunderrepresented in the grab samples.\nare more available to the fishes in the south. In\nSome patterns are apparent from the Polar Star\nthe northeastern Bering Sea, cold, year-round\ndata. First, infaunal species richness and biomass\nwater temperatures at the sea floor effectively ex-\nare relatively high in the outer shelf and slope por-\nclude flatfishes from large portions of the continen-\ntions of the Navarin Basin and low on the inner\ntal shelf and their food resources (Neiman 1963).","","Chapter 6.\nFishery Resources\nFREDRIK V. THORSTEINSON\nFritz Cove, Auke Bay, Alaska\nTERRANCE M. SAMPLE\nU.S. Department of Commerce, NOAA, National Marine Fisheries Service,\nNorthwest and Alaska Fisheries Center, Seattle, Washington\nAND\nLYMAN K. THORSTEINSON\nU.S. Department of Commerce, NOAA, National Ocean Service, Office of Oceanography and Marine Services,\nOcean Assessments Division, Alaska Office, Juneau, Alaska\nThe Navarin Basin planning unit is almost equal-\nhave varied between years. However, during 1975\nly divided between shallow continental shelf\nand each year from 1979 to 1982 sampling efforts\nwaters 40-200 m in depth and the slope and deep\nwere extended into the Navarin Basin lease area.\nwaters off the shelf which reach depths of up to\nThese were the most comprehensive surveys ever\n3,500 m. Even though the area is the most poorly\nconducted in the Bering Sea with respect to area\nknown of proposed Alaska OCS lease areas be-\nand habitat coverage as well as subsequent biol-\ncause of its remoteness from human habitation and\nlogical data collections.\nseasonal ice cover, a considerable body of infor-\nThese surveys, while providing valuable infor-\nmation exists for fishery resources of the basin.\nmation about the Navarin Basin, are limited by the\nThe primary sources of information are from\nextent of area and depth zone coverage and lack\ncommercial fishery catch statistics and demersal\nof seasonal data. Most large-scale NWAFC surveys\ntrawl surveys conducted by the National Marine\nhave been conducted during the summer months\nFisheries Service (NMFS).\nof June through August. Seasonal information is\nThe Bering Sea has been a major fishing area\nconfined to early fall data collected in 1975 and\nfor foreign groundfish trawlers and has attracted\ninferences from catch data collected during the\nfleets from Japan, the Republic of Korea (South\n1976 spring survey in eastern Bering Sea waters\nKorea), Poland, Taiwan, West Germany, and, until\nsouth of the Navarin Basin. The 1979, 1981, and\n1980, the U.S.S.R. Unlike other OCS areas off\n1982 surveys were cooperative efforts between the\nAlaska, the commercial trawl fishery in the\nNWAFC and the Far Seas Fisheries Agency of\nNavarin Basin is conducted solely by these foreign\nJapan and sampled both continental shelf and\nfleets and is dominated by Japan. Japan also con-\nslope waters to about 1,200 m. Due to limited time\nducts a high seas mothership gillnet fishery in and\nand vessel allocations, the 1980 survey area was\nnear th area.\nrestricted to waters less than 200 m deep. Approx-\nThe NMFS Northwest and Alaska Fisheries\nimately 46% of the Navarin Basin region east of\nCenter (NWAFC) has conducted demersal trawl\n180° was sampled in 1980 and 1982, and about\nsurveys of the southeastern Bering Sea annually\n59% in 1981. Unfortunately, 1982 data from the\nsince 1971. Area coverage and sampling intensity\nslope portion (> 200 m) of the survey area are not\n63","64\nNavarin Basin Synthesis\ncod. which average only 2.9% of the catch in the\nyet available for review.\nNavarin Basin, amounted to 29.6% of the total\nBering Sea catch east of the U.S.-U.S.S.R. Conven-\n6.1 ICHTHYOFAUNA\ntion Line.\nThe most frequently encountered (and most\nSome 300 species of fish occur in the Bering Sea,\nabundant) species of demersal fishes taken dur-\nmost in the southern areas (Wilimovsky 1974).\ning the 1981 cooperative U.S. Japan survey were\nAlthough fish biomass is relatively high in the\ngenerally those most important in the commer-\nNavarin Basin, the number of species inhabiting\ncial fisheries. Relative importances of species\nthe area is lower than in proposed lease areas to\nencountered in the Navarin Basin area by catch\nthe south. The NMFS encountered approximately\nper unit effort (CPUE) during the 1981 cooperative\n86 fish species and 3 commercially important crab\nU.S.-Japan survey are given below (Sample 1982):\nspecies, as well as numerous noncommercially\nimportant invertebrates during the 1981 survey.\nCPUE\nThis may be at least partially explained by temp-\nSpecies\n(kg/ha)\nerature-dependent range limitations or seasonal\nWalleye pollock\n63.0\nmigrations. Commercially important species of\nGreenland turbot\n15.5\ndemersal fishes are known to migrate from shal-\nPacific cod\n15.0\nlow to deeper waters in the winter and spring.\nFlathead sole\n4.0\nThese movements are most extensive for species\nArrowtooth flounder\n2.6\nthat occupy inner shelf regions during the sum-\nSablefish\n1.7\nmer, such as yellowfin sole, rock sole, Alaska\nPacific halibut\n0.2\nplaice, and Pacific halibut. As a result of shifts to\nRock sole\n0.2\ndeeper water and some southward movements,\nAlaska plaice\n0.2\ncommercially important demersal fishes are more\nPacific herring\n> 0.1\nabundant in the central Bering Sea during the\nAs mentioned earlier, yellowfin sole were not\nwinter and spring than in the summer. (Commer-\nobserved in the Navarin Basin during this survey.\ncially important finfish species inhabiting the\nVariations do occur from year to year as a result\nNavarin Basin are listed in Table 6.1.)\nof differences in area and depth sampled, changes\nTo place the Navarin Basin in perspective in\nin sampling gear, and seasonal movements of fish.\nrelation to species abundances within it and their\nMorris (1981) reported average catches in kilo-\ncomparative importance in the total Bering Sea\ngrams per half-hour trawl for the Navarin Basin\narea, groundfish catches were examined by aver-\nportion of the 1975 NMFS survey for important\naging total catches for each area for the period\ncommercial fishes:\n1977-79 (Table 6.2). Because the foreign trawl\nfleets operate year round, their catches yield in-\nMean Catch\nformation on commercially important species that\nSpecies\n(kg/30 min)\noccupy the Navarin Basin seasonally and that were\nWalleye pollock\n469\neither seldom encountered in the NMFS summer\nGreenland turbot\n69\nsurveys, such as the yellowfin sole, or present in\nPacific cod\n28\nlow abundance, such as rock sole, Pacific halibut,\nFlathead sole\n23\nAlaska plaice, and Pacific herring.\nRock sole\n8\nPollock, flatfishes, and Pacific cod compose the\nYellowfin sole\n3\nmajor portion of the commercial trawl catch in\nA major task assigned to the Fisheries Workshop\nthe Navarin Basin, with pollock predominating.\nat the Navarin Basin Synthesis Meeting was to\nOver the 3-year period of 1977-79 pollock aver-\nassess possible biological consequences of hypo-\naged about 84% of the total Navarin catch while\nthetical oil spills in the basin. Species importance\naccounting for an average of 37% of the total\nBering Sea take of pollock during the same period.\nin commercial catch and resource assessment\nsurvey statistics formed the basis for selection of\nFlatfishes averaged only 7.2% of the Navarin Basin\ncatch and 14.7% of the Bering Sea total. Pacific\npollock, Pacific cod, Greenland turbot, flathead","Fishery Resources\n65\nsole, rock sole, and yellowfin sole for workshop\nto conduct operations in these waters during 1980\ndiscussions of hypothetical spills. The results of\nand 1981 (Table 6.3). Marine fishery effort is\nthese discussions are presented in Chapter 9.\ndirected toward trawling for pollock, with a\nsmaller number of longliners fishing for Pacific cod\n6.2 COMMERCIAL FISHERIES (FINFISH)\nand sablefish. An impressive number of vessels\noperated in the area, varying seasonally from a\nThe Navarin Basin is located in an area of\nlow of 69 to as many as 192 in any one month\nproductive fisheries and intensive foreign fishing\nduring these years (Table 6.4).\nactivity. Under the Fishery Conservation and Man-\nThe combined catches of the Japanese mother-\nagement Act of 1976, six nations were permitted\nship and South Korean groundfish fisheries ac-\nTABLE 6.1-Finfish species of commercial importance inhabiting the\nNavarin Basin region.\nCommon Name\nScientific Name\nHerrings\nClupeidae\nPacific herring\nClupea harengus pallasi\nSalmon\nSalmonidae\nChinook salmon\nOncorhynchus tshawytscha\nChum salmon\nO. keta\nCoho salmon\nO. kisutch\nPink salmon\nO. gorbuscha\nSockeye salmon\nO. nerka\nCodfishes\nGadidae\nPacific cod\nGadus macrocephalus\nWalleye pollock\nTheragra chalcogramma\nRockfishes\nScorpaenidae\nBlue rockfish\nSebastes mystinus\nDarkblotched rockfish\nS. crameri\nDusky rockfish\nS. ciliatus\nPacific Ocean perch\nS. alutus\nRougheye rockfish\nS. aleutianus\nShortraker rockfish\nS. borealis\nSilvergray rockfish\nS. brevispinis\nShortspine rockfish\nSebastolobus alascanus\nThornyhead rockfish\nS. altivelis\nSablefishes\nAnoplopomatidae\nSablefish\nAnoplopoma fimbria\nGreenlings\nHexagrammidae\nAtka mackerel\nPleurogrammus monopterygius\nFlounders\nPleuronectidae\nAlaska plaice\nPleuronectes quadrituberculatus\nArrowtooth flounder\nAtheresthes stomias\nBering flounder\nHippoglossoides robustus\nFlathead sole\nH. elassodon\nGreenland turbot\nReinhardtius hippoglossoides\nPacific halibut\nHippoglossus stenolepis\nRock sole\nLepidopsetta bilineata\nYellowfin sole\nLimanda aspera","Navarin Basin Synthesis\n66\nherring was proclaimed a prohibited species in\ncounted for approximately 97% of the overall\n1980, thus ending the foreign fishery targeted on\nforeign nation catch in 1981 and about 95% in\nthis species.\n1980. Distributions of annual combined species\nBecause Japan conducts the major foreign\ncatches made by these two fisheries are shown\nfishery in the eastern Bering Sea, historical\nin Figures 6.1 and 6.2 for the years 1980-81. The\nJapanese catch statistics provide a reasonably\nlargest catches (exceeding 20,000 t) in the Navarin\ngood index of overall fishing effort conducted\nBasin area generally occurred along the continen-\nthere. Annual catches of species and species\ntal shelf break. Similar distribution and relative\ngroups made by Japanese vessels in the Navarin\nabundance trends were observed for roundfishes\nBasin and mean overall catches are shown in\nand flatfishes as well as for the biomass dominants,\nTable 6.5 for the years 1972-81. Approximately\nwalleye pollock and Greenland turbot, taken\n32% of the total eastern Bering Sea pollock catch\nduring the NWAFC 1981 survey (Figs. 6.3-6.6).\nwas taken in the Navarin Basin during those years.\nApproximately 140,000 t or 13% of the overall\nAdditionally, about 12% of the overall flatfish\ncombined Japanese-South Korean groundfish\ncatch and 25% of the Pacific cod catch were taken\ncatch was made in the Navarin area during 1981\nin the basin during this period. Pacific herring in\nwhile about 364,000 t or 34% of the total eastern\nthe Navarin region composed about 58% of the\nBering Sea catch was taken from this region in\ntotal annual average herring catch until 1980\n1980. Walleye pollock was the predominant\nwhen herring was designated a prohibited species.\nspecies taken, representing 92% and 95% of the\nApproximately 20% of the average annual catch\ntotal catch in the Navarin Basin during 1980 and\nof the other commercial species category (includ-\n1981, respectively; other species taken included\ning Atka mackerel, rockfishes, and sablefish) were\nthe flatfish category (arrowtooth flounder, Green-\ntaken in the Navarin Basin. U.S. fishing effort, with\nland turbot, Bering flounder, flathead sole, Alaska\nthe exception of limited joint venture activity and\nplaice, and other flounders), rockfishes, rattails,\nthe blue king crab pot fishery around St. Matthew\nsablefish, Pacific cod, and Atka mackerel. Pacific\nTABLE 6.2-Relative importance of major commercial species within the Navarin\nBasin and Bering Sea as measured by average groundfish catches of foreign\nnations, 1977-79.\nNavarin Basin Catch\nMean\n% of Total\n% of Mean\nMean\nBering Sea\nNavarin Catch\nBering Catch\n(t)\nCatch (t)\nSpecies\n83.8\n37.1\n340,600\n917,533\nWalleye pollock\n2.9\n29.6\n11,867\n40,033\nPacific cod\n0.1\n3.8\n3,467\n90,567\nYellowfin sole\n0.5\n22.7\n2,033\n8,967\nGreenland turbot\n5.9\n28.5\n23,800\n83,530\nOther flounders*\n0.2\n12.6\n733\n5,833\nPacific Ocean perch\n0.4\n14.2\n1,733\n12,166\nOther rockfishest\n< 0.1\n10.4\n290\n2,800\nSablefish\n< 0.1\n0.1\n20\n22,867\nAtka mackerel\n5.4\n36.2\n21,800\n60,300\nOthers#\n32.6\n406,343\n1,244,596\nTotal\nSOURCE: Data from NOAA, National Marine Fisheries Service, Juneau, Alaska.\nRock sole, arrowtooth flounder, flathead sole. and Alaska plaice.\n*\n+ Darkblotched, rougheye, shortraker, blue, dusky, shortspine, thornyhead, and silver-\ngray rockfishes.\nI Sculpins, eelpouts, poachers, and skates.","Fishery Resources\n67\n165\n170\n175°\n180\n175\n170\n165\n160\n155\n150\n63\n63\n61\n3\nT\n4\nT\n59\n59°\n2\n5\n1\n10/16\n7\n3\n14 22\n7\n9\n22\nT\n9\n2\n2\n1-37\n4\n12\n18\n11\n9\n2\n20\nT\n37\n6\n16\n19\n8\nT\n57\n57\n19\n15\n3\n18\nT\n4\n2\n15\nT\nT\n7\n17\n8\n5\n1\n1\n3\n15\n3\n43\n38\n5\nT\nT\n4\n11\n4\n7\n5\n6-12\n12\nFIGURE 6.1-Distribution\n9\n2\n2\n3\n1\n7\n55\n25\n55\n25\n35\nof combined catches of the\n17\n11\nT\n33\n22\nT\nJapanese mothership and\n15\n26\n51\n3011\n62\n7\nSouth Korean fisheries in\n53\n53\nthe eastern Bering Sea\n(1,000 t) east of 180° by\n1/2° latitude and 1° longi-\n51\n51'\ntude in 1980. (T = catch\n< 500 t.)\n165\n160\n175\n180\n175\n170\n150\n175\n170°\n165\n160\n155\n165\n170\n175\n180\n63\n63\n61\n61\n59\n59\n2\n57\n57\n12\n26\n20\n12\nFIGURE 6.2-Distribution\n30\n14\n55\n55\nof combined catches of the\n2\n25\n30\n58\n55\nJapanese mothership and\nSouth Korean fisheries in\n53\nthe eastern Bering Sea\n(1.000 t) east of 180° by\n1/2° latitude and 1° longi-\ntude in 1981. (T = catch\n< 500 t.)","Navarin Basin Synthesis\n68\nIsland, has been minimal in the Navarin Basin\n178°\n176°\n174°\n172°\nregion. The Navarin Basin does, however, consti-\n63°\n63°\nTOTAL FLATFISH\ntute an area of potential U.S. fisheries development\nCatch in kg/ha\nNo catch\nfor Pacific herring, golden, or brown, king crab\n< 15\n15-100\n(Lithodes aequispina), and possibly other ground-\n62°\n62\n100-200\nfish species such as pollock and the turbots.\n200\nSince 1977, conservation measures in the form\nof prohibitions on the foreign fleets from taking\n61°\n61\ncertain species of fishes and crabs were: 1977,\nhalibut and king crab; 1978, herring; and 1979,\nTanner crabs. Nevertheless, large numbers of\n60°\n60°\nthese species are taken as by-catch while trawl-\ning for pollock and other demersal species in the\nNavarin Basin (Table 6.6). When taken, these\n59°\n59\nspecies must be returned to the sea.\nJapan is the only nation having a directed\nfishery for Pacific salmon in or near the Navarin\n58°\nBasin, but restrictions in the form of area closures\n58\nhave also been placed to protect stocks of western\n178°\n176°\n174°\n172°\nAlaska salmon.\nThe gillnet catch for 1980 and 1981 in and ad-\nFIGURE 6.3-Distribution and relative abundance of\njacent to the Navarin Basin by 2° X 5° blocks for\ntotal flatfish during the 1981 NWAFC eastern Bering\nall species of Pacific salmon is given in Table 6.7.\nSea survey including the Navarin Basin.\nThe Japan Fishery Agency believes the pink\nsalmon taken in this area are mainly of Asian\norigin, as are about 95% of the chum salmon (M.\nL. Dahlberg pers. commun.). About 75% of the\nsockeye salmon caught are immature, and of these\nabout 40% are Bristol Bay stocks. Chinook salmon\n178°\n176°\n174°\n172°\nare of special concern as almost all taken in the\n63°\n63°\nTOTAL ROUNDFISH\nCatch in kg/ha\nNavarin Basin are immature and ultimately des-\nNo catch\ntined for western Alaska rivers, principally the\n<15\n15 -100\n62°\nYukon and Kuskokwim.\n62°\n100-200\n> 200\n6.3 COMMERCIAL FISHERIES (SHELLFISH)\n61°\n61°\nAt present no foreign commercial fishery for\nshellfish occurs in the Navarin Basin. King and\na\nTanner crabs are prohibited species and must be\n60°\n60°\nreturned to the sea when taken. Significant popula-\ntions of crabs inhabit the region as indicated by\nnumbers taken as by-catch from 1977 to 1979\n59°\n59°\n(Morris 1981):\nYear\nKing Crab\nTanner Crab\n1977\n522,929\n6,647,308\n58°\n58°\n1978\n1,767,025\n5,911,654\n178°\n176°\n174°\n172°\n1979\n523,189\n4,941,861\nIn 1979 the incidental king crab catch was com-\nFIGURE 6.4 - Distribution and relative abundance of\nposed of 8% red king crab, 1% blue, and 91%\ntotal roundfish during the 1981 NWAFC eastern Bering\nSea survey including the Navarin Basin.\ngolden (French et al. 1981).","Fishery Resources\n69\nThe Tanner crab Chionoecetes opilio was the\nBiomass estimates of commercially important\nmost frequently encountered commercially impor-\ncrab species, based on NWAFC data, have been\ntant crab species in the Navarin Basin during the\ndeveloped by Sample (1982) for 1980-82 and are\n1981 NWAFC surveys; greatest concentrations\ngiven in Table 6.8.\nwere observed at water depths less than 120 m.\nThree principal species of shrimp are found in\nAll C. bairdi taken were in depths from 120 to 200\nthe Bering Sea: sidestripe shrimp, Pandalopsis\nm. Only small numbers of blue king crab were\ndispar; pink shrimp, Pandalus borealis; and humpy\nobserved and no red king crab were taken. Golden\nshrimp, P. goniurus. These species are most abun-\nking crab were infrequently present in catches\ndant along the central outer shelf and slope of the\nbecause their distribution is largely restricted to\ncentral Bering Sea. The species of primary com-\ndeep slope waters beyond the survey area. Data\nmercial interest in the Bering Sea is the pink\ncollected by observers aboard foreign trawlers\nshrimp. The main pink shrimp fishery grounds\nshow that golden king crab are generally\nused to be to the northwest of the Pribilof Islands\ndistributed between 200 and 2,000 m along the\n(Fig. 6.10). Japan and the U.S.S.R. began fishing\ncontinental slope (McBride et al. 1982). Distribu-\nfor shrimp in the early 1960's. Japan's fleets\ntion and relative abundance of Tanner crabs and\nconcentrated their efforts in the region north of\nblue king crab are shown in Figures 6.7-6.9.\nthe Pribilofs and achieved a peak catch of 27,000\nTABLE 6.3-Foreign fishing activity by nation and vessel type in the Navarin Basin, 1980-81.\nVessels/\nYear\nand Nation\nVessel Type\nTarget Species\nSeason\nMonth\n1980:\nAll year\n0-7\nJapan\nLongliners\nPacific cod\nSalmon fleets\nSalmon\nJune-July\n0-176\nFactory fleets\nPollock, flounder\nApr.-Oct.\n0-90\nIndependent trawl\nPollock\nAll year\n39-96\nPot vessels\nCrab, snail\nFeb.-Sept.\n0-18\nU.S.S.R.*\nIndependent trawl\nPollock\nJan.-Mar.\n0-17\nS. Korea\nLongliners\nSablefish\nJune\n1\nIndependent trawl\nPollock\nAll year\n0-3\n0-3\nTaiwan\nIndependent trawl\nPollock\nAll year\n0-12\nPoland\nIndependent trawl\nPollock\nAll year\nW. Germany\nIndependent trawl\nPollock\nDec.\n1\n1981:\nJapan\nLongliners\nPacific cod\nAll year\n1-11\nSalmon fleets\nSalmon\nJune-July\n0-176\nFactory fleets\nPollock, flounder\nMay-Aug.\n0-72\nIndependent trawl\nPollock\nAll year\n33-99\n0-2\nPot vessels\nSnail\nMay-Aug.\nJan.\n1\nS. Korea\nLongliners\nSablefish\n1-23\nIndependent trawl\nPollock\nAll year\nAll year\n0-3\nTaiwan\nIndependent trawl\nPollock\nFeb.-June\n0-19\nPoland\nIndependent trawl\nPollock\nW. Germany\nIndependent trawl\nPollock\nAll year\n0-1\nSOURCE: Data from NOAA, National Marine Fisheries Service. Juneau, Alaska.\nSoviet vessels authorized for joint ventures only after March 1980.","Navarin Basin Synthesis\n70\n178°\n174°\n170°\n166\no\n162°\n158\n63°\n63°\nALASKA\n61\no\n61\n59°\n59°\n57°\n57°\nPOLLOCK\nCatch kg/ha\nNo catch\n5 15\nFIGURE 6.5 - -Distribution\n15-100\nand relative abundance of\n100\n55°\n55°\nwalleye pollock during the\n1981 NWAFC eastern Ber-\ning Sea survey including\n178°\n174°\n170°\n166°\n162°\n158°\nthe Navarin Basin.\n178°\n174°\n170°\n166°\n162°\n158\n63°\n63°\nALASKA\n200 -\n61°\n61\n59°\n59°\n57°\n57°\nGREENLAND TURBOT\nCatch kg/ha\nNo catch\n+\nFIGURE 6.6-Distribution -\n< 10\n10-25\nand relative abundance of\n> 25\n55°\n55°\nGreenland turbot during\nthe 1981 NWAFC eastern\nBering Sea survey includ-\n178°\n174°\n170°\n166°\n162°\n158°\ning the Navarin Basin.","Fishery Resources\n71\n178°\n174°\n170°\n166°\n162°\n158°\n63\n63°\n100 m\nALASKA\n61\n61°\n59°\n59°\n@\nE\n57°\n57°\nTANNER CRAB\nc. 001110\nCatch kg/ha\nFIGURE 6.7-Distribution\nNo catch\nand relative abundance of\n< 10\n10-25\nTanner crab, Chionoecetes\n25-40\n55°\n55°\nopilio, during the 1981\n40\nNWAFC eastern Bering\nSea survey including the\n178°\n174°\n170°\n166°\n162°\n158°\nNavarin Basin.\n178°\n174°\n170°\n166°\n162°\n158°\n63°\n63°\nALASKA\n61°\n61\n59\n59\n57°\n57°\nTANNER CRAB\nFIGURE 6.8 -Distribution -\nand relative abundance of\nTanner crab, Chionoecetes\n55°\n55°\nbairdi, during the 1981\nNWAFC eastern Bering\nSea survey including the\n178°\n174°\n170°\n166°\n162°\n158°\nNavarin Basin.","Navarin Busin Synthesis\n72\n162°\n158°\n170°\n166°\n178°\n174°\n63°\n63°\nALASKA\n61\no\n61\nO\n59°\n59\n57°\n57°\nBLUE KING CRAB\nCatch kgiha\nNo carch\n10\nFIGURE 6.9-Distribution -\n10-25\nand relative abundance of\n25-40\n55°\n55°\n40\nblue king crab during the\n1981 NWAFC eastern Ber-\ning Sea survey including\n162°\n158°\n178°\n174°\n170°\n166°\nthe Navarin Basin.\n160°\n155°\n170°\n165°\n175°\n180°\n175°\n65'\n65\nO\n60°\n60\n55\n55\n0\n0\nFIGURE 6.10-Main - fishing\n170°\n165°\n160°\n155°\n175°\n180°\n175°\ngrounds for pink shrimp\nin the Bering Sea.","Fishery Resources\n73\nregulatory mechanisms (Laevastu and Marasco\nt. After 1963 the Japanese effort and catch de-\n1982). Changes in stock composition have been\nclined rapidly, and by 1966 commercial efforts\nobserved in the form of shifts in age class strength\nwere no longer profitable due to overfishing.\n(and, ultimately, in biomass) in systematic survey\nShrimp stocks have remained depressed and fish-\ndata, but are not usually recognizable in commer-\ning has not been resumed.\ncial catch records. The inability of commercial\nA small, but important, pot fishery for snails also\ncatch statistics to discriminate stock composition\ntakes place in the Navarin Basin. The snail catch\nchanges is a direct result of rapid technological\nis taken primarily between the Pribilofs and St.\nadvances in fish-finding and capturing capabilities\nMatthew Island with a relatively minor contribu-\nwhich change catch per unit effort (CPUE), thereby\ntion from the southern portion of the Navarin\nmaking comparisons between years difficult.\nBasin; it amounts to almost 240 t per year.\nEnvironmental anomalies, such as changes in\nsea surface or bottom temperatures, are often\n6.4 FACTORS AFFECTING\ncorrelated with unusual year class successes or\nFISHERY RESOURCES\nfailures. The critical roles of temperature and other\nenvironmental variables in migratory and repro-\nFish population numbers and biomasses are\nductive behavior, predator-prey relationships, and\nconstantly changing in space and time. These fluc-\ngrowth, recruitment, and availability of stocks can-\ntuations are thought to reflect (1) environmental\nnot be overemphasized. As discussed above, most\nand fishing pressures and (2) various internal\nTABLE 6.4-Foreign fishing activity by number of vessels each month in the Navarin Basin, 1980-82.\nYear\nSept.\nOct.\nNov.\nDec.\nFeb.\nMar.\nApr.\nMay\nJune\nJuly\nAug.\nand Nation\nJan.\n1980:\n148\n113\n76\n60\n114\n123\n99\n151\n184\n148\n123\nJapan\n81\n7\n18\n21\n5\n4\n1\n1\nS. Korea\n17\n21\n20\n16\n16\n6\n8\n0\n0\n0\n0\n0\nPoland\n0\n10\n10\n12\n6\n0\n0\n1\n0\n0\n0\nTaiwan\n2\n3\n3\n3\n3\n3\n0\n0\n0\n0\n0\n0\n0\n0\n0\n0\nU.S.S.R.\n15\n0\n0\n0\n0\n0\n0\n0\n0\n0\n0\n0\nW. Germany\n0\n0\n149\n120\n100\n90\n130\n176\n192\n153\n124\nTotal\n115\n148\n156\n1981:\n66\n80\n73\n58\n95\n118\n75\n143\n132\n82\n83\nJapan\n80\n3\n0\n4\n11\n13\n4\n0\n1\nS. Korea\n20\n21\n19\n12\n0\n0\n0\n16\n3\n0\n0\n0\nPoland\n0\n1\n2\n19\n2\n0\n1\n0\n0\n0\n0\nTaiwan\n0\n1\n1\n1\n1\n0\n1\n0\n0\n0\n0\n0\nW. Germany\n1\n1\n1\n1\n0\n73\n84\n69\n80\n78\nTotal\n101\n119\n141\n108\n173\n139\n82\n1982:\n_*\n83\n72\n71\n96\n84\nJapan\n86\n106\n118\n92\n139\n110\n5\n2\n0\n1\nS. Korea\n21\n26\n11\n10\n16\n0\n2\n-\n2\n0\n0\n2\n0\n0\n0\nTaiwan\n0\n0\n0\n1\n-\n0\n0\nW. Germany\n0\n0\n0\n0\n0\n1\n0\n0\n0\n-\n87\n110\n85\n77\n73\n96\nTotal\n108\n132\n140\n103\n157\n-\nSOURCE: Data from NOAA National Marine Fisheries Service, Juneau, Alaska.\nNOTE: Excludes high-seas salmon fleets and foreign vessels conducting joint ventures.\nDecember 1982 data not yet available","74\nNavarin Basin Synthesis\nTABLE 6.5 - Annual and mean groundfish catches (t) by Japanese vessels within the Navarin Basin, mean Bering\nSea catch, and percentage of Bering Sea catch within the Navarin Basin, 1972-81.\nOther\nWalleye\nPacific\nPacific\nCommercial\nTotal\nHerring\nSpecies*\nCatch\nYear\nPollock\nFlatfishes\nCod\n1972\n378,165\n18,280\n6,363\n909\n3,240\n411,766\n1973\n888,079\n22,690\n18,519\n28\n2,372\n945,122\n291\n2,394\n525,393\n1974\n472,470\n17,283\n14,117\n627\n1,435\n328,715\n1975\n288,350\n16,324\n8,350\n1976\n249,163\n15,089\n6,420\n9,599\n1,038\n296,211\n1977\n294,225\n17,846\n9,584\n3,417\n1,999\n336,795\n1978\n288,140\n27,117\n13,393\n1,953\n1,522\n345,327\n1,310\n1,169\n235,239\n1979\n199,846\n15,943\n6,478\n47\n2,204\n338,056\n1980\n303,117\n17,579\n5,737\n1981\n124,022\n2,218\n1,079\n0\n93\n128,375\nMean Navarin catch\n348,552\n17,037\n9,004\n1,818\n1.747\n389,100\nMean Bering Sea\n35,353\n3,164\n8,804\n1,267,038\ncatch\n1,078,033\n141,684\nPercentage of\nBering Sea catch\nwithin Navarin Basin\n32%\n12%\n25%\n58%\n20%\n31%\nSOURCE: Data from NOAA, National Marine Fisheries Service, Juneau, Alaska.\n*\nIncludes Atka mackerel, rockfishes, and sablefish.\nTABLE 6.6-Estimated incidental catch of prohibited species by foreign fisheries operating\nin the Navarin Basin and the entire U.S. FCZ in the Bering Sea, 1977-81.\nCatch*\nPercentage of Navarin Catch by Nation\nSpecies\nNavarin\nBering\nRepublic\nand Year\nBasin\nSea\nJapan\nU.S.S.R.\nof Korea\nOthers\nPacific halibut\n1977\n614\n2,232\n99.5\n0.4\n< 0.1\n< 0.1\n1978\n1,120\n3,686\n96.8\n2.5\n0.7\n< 0.1\n1979\n279\n3,238\n94.5\n2.0\n3.7\n0\n1980\n711\n4,311\n95.0\n5.0\n0\n-\n1981\n541\n2,704\n91.8\n6.9\n1.3\n-\nPacific salmon\n1977\n13,930\n51,171\n75.0\n9.5\n15.5\n< 0.1\n1978\n30,950\n44,288\n93.0\n6.9\n0\n0.1\n1979\n41,480\n110,473\n73.0\n8.8\n18.2\n0\n1980\n75,065\n120,104\n80.5\n18.9\n0.6\n-\n1981\n10,161\n42,337\n66.0\n21.4\n12.6\n-\nPacific herringt\n1977\n16,933\n18,162\n22.4\n77.5\n0\n0\n1978\n8,193\n8,397\n25.4\n74.5\n0.1\n0\n1979\n6,371\n6,547\n20.7\n78.3\n1.0\n0\nSOURCE: Morris 1981, revised.\n*\nCatch reported in metric tons for halibut and herring, and in number of fish for salmon.\n+ Pacific herring data not available for 1980 and 1981.","Fishery Resources\n75\nTABLE 6.7-Japanese mothership gillnet catch of Pacific salmon by 2° X 5° blocks in and near the Navarin Basin,\n1980 and 1981.\nSockeye\nChum\nPink\nCoho\nChinook\n2° 5°\nBlock*\n1980\n1981\n1980\n1981\n1980\n1981\n1980\n1981\n1980\n1981\n17556\n36,703\n63,463\n411,837\n280,835\n44,959\n337,884\n14\n46\n190,251\n10,752\n17558\n753\n2,225\n5,432\n6,640\n4,605\n15,223\n0\n0\n7,948\n227\n18056\n43,964\n46,052\n360,168\n250,073\n101,434\n280,443\n20\n37\n205,212\n8,650\n18058+\n2,227\n2,827\n20,587\n16,617\n8,730\n30,182\n0\n0\n12,930\n810\nSOURCE: Data from NOAA, NMFS, Auke Bay Biological Laboratory, Auke Bay, Alaska.\nBlock numbers identified by longitude and latitude at lower left corner of blocks.\nt Within Navarin Basin OCS planning unit.\nspecies inhabiting the Navarin Basin have been\nspecies. Within a given spawning or nursery area,\nfished extensively and will continue to be harvest-\nthe densities of early life stages present will\ned in increasing numbers throughout this century.\ninfluence levels of inter- and intraspecific competi-\nLarge-scale annual removals will certainly affect\ntion and predation and, therefore, survival rate\nstock compositions and reproductive potentials.\nof a species to various age or size classes.\nDensity-dependent factors are also responsible for\nBecause populations fluctuate in response to a\nshifts in biomass with time (Ricker 1975).\nmyriad of environmental and population variables,\nInternally, populations regulate themselves to\nage-specific mortality rates are poorly understood.\ncarrying capacity through increases and decreases\nLarval recruitment usually assumes a 95 to 99%\nin growth rates, changes in trophic relationships,\nmortality rate from the egg stage. Stock replace-\nand reproductive potentials. The number of ma-\nment theory implies one embryo survives to repro-\nture adults may limit the spawning success of a\nductive age for each spawning adult (Ricker 1975).\nTABLE 6.8-Estimated biomass (t) of commercially important crab species in the Navarin Basin and in the overall\nNMFS eastern Bering Sea summer survey areas of 1980-82.\n1980 Survey\n1981 Surveyt\n1982 Survey#\nPercentage of Total\nin Navarin Basin\nTotal\nTotal\nTotal\nNavarin\nSurvey\nNavarin\nSurvey\nNavarin\nSurvey\n1980\n1981\n1982\nSpecies\nBasin\nArea\nBasin\nArea\nBasin\nArea\nSurvey\nSurvey\nSurvey\nRed king crab\nParalithodes\ncamtschatica\n0\n213,100\n0\n121,500\n0\n136,000\n0\n0\n0\nBlue king crab\nP. platypus\n1,900\n168,000\n1,200\n27,500\n2,900\n26,400\n11.3\n4.4\n11.0\nTanner crab\nChionoecetes\nopilio\n141,300\n592,500\n55,400\n292,520\n60,800\n404,800\n23.8\n18.9\n15.0\nTanner crab\nC. bairdi\n21,700\n212,400\n20,500\n97,900\n57,900\n141,000\n10.2\n20.9\n41.1\nTotal\n164,900\n1,186,000\n77,100\n539,420\n121,600\n708,200\n13.9\n14.3\n17.2\n*\nThe 1980 survey area covered only continental shelf waters < 180 m in depth.\nt The 1981 survey was a cooperative NWAFC-Japan survey covering shelf and slope waters to 1,100 m in depth.\n+ The 1982 survey was a cooperative NWAFC-Japan-U.S.S.R survey; however, only NWAFC trawl data covering the con-\ntinental shelf region (< 180 m depth) were available for consideration.","76\nNavarin Basin Synthesis\nMany environmental factors determine the\nficiencies associated with differing vessels and gear\n\"health\" of a population at any given time. Because\ncatchabilities (Pereyra et al. 1976). However, the\npopulations are dynamic, biomass estimates from\nNMFS survey data do provide the best available\noccasionally surveyed regions are soon dated. Such\nindices of population status of major species of the\nestimates suffer also from limitations in fishing ef-\nNavarin Basin.","Chapter 7.\nMarine Birds\nALAN M. SPRINGER\nFALCO, Fairbanks, Alaska\nAND\nJOSEPH G. STRAUCH, JR.\nScience Applications, Inc., Boulder, Colorado\n7.1 PELAGIC DISTRIBUTION OF SEABIRDS\nThe highest densities of pelagic birds in the\nsoutheastern Bering Sea occur in summer and fall\nSystematic surveys of pelagic birds in the Navarin\n(Figs. 7.4 and 7.5) and result mainly from increases\nBasin planning unit were made for the first time\nin the numbers of shearwaters. For species other\nin 1982 (Hunt 1982). Shuntov (1972) summarized\nthan shearwaters, overall density has a tendency\nRussian observations for the entire Bering Sea and\nto peak in the spring (Fig. 7.6). This spring peak,\ngave a general account of distributions in the\nhowever, reflects the concentrating effect that ice\nNavarin area (Fig. 7.1). Extensive data exist on the\ncover has rather than indicating a larger total\npelagic distribution of birds in the southeastern\npopulation. From June through September, the\nBering Sea (Hunt et al. 1981c).\nShort-tailed Shearwater (Puffinus tenuirostris) is the\nThe Navarin Basin includes three marine do-\nmost abundant species in the Bering Sea. Shear-\nmains (Fig. 7.2), which have been described for\nwaters are typically found over the continental\nshelf, with only moderate numbers occurring over\nthe southeastern Bering Sea by Iverson et al.\n(1979). The distribution of birds within these\nthe shelf break. In the Bering Sea they concen-\ndomains is probably related to trophic differences\ntrate near and within the 50-m isobath. Flocks of\nbetween species (Hunt et al. 1981c), and to\nat least 100,000 are common, and flocks of over\n1 million have been recorded. Shearwaters were\noceanographic processes that lead to distinctive\nnot encountered in large numbers within the\nfood webs in the different domains.\nA preliminary analysis of survey data from 1982\nNavarin Basin, but they can be easily missed\nbecause of their clumped distribution.\nindicates that overall densities of seabirds (ex-\nMurres are abundant and widespread in the\ncluding shearwaters, Puffinus spp.) in the ice-free\nsoutheastern Bering Sea (Shuntov 1972). Both\nseason (Table 7.1) are similar to densities in the\nCommon (Uria aalge) and Thick-billed (U. lomvia)\nsame domains in the southeastern Bering Sea\n(Table 7.2). Decreasing bird densities in the slope\nMurres are present, but because they are difficult\nto distinguish in the field, observations of these\nand shelf domains, and increasing densities near\nSt. Matthew Island between May-June and July-\nspecies are usually combined. Murres are most\ncommonly found over the continental shelf (Table\nAugust sampling intervals reflect consolidation of\nbirds at breeding colonies during early summer.\n7.2). They frequent areas of open water in the\nspring, concentrate around the major breeding col-\nThe density distribution of seabirds by date and\ndomain is approximately normal (Fig. 7.3), sug-\nonies in the summer, and again disperse over the\ncontinental shelf in the fall. Murres are the most\ngesting a more uniform rather than patchy distribu-\nabundant seabirds wintering in the Bering Sea and\ntion of birds at sea. Concentrations greater than\n100 birds/km2 were infrequent (Table 7.3).\nbecause they stay on or below the sea surface they\n77","Navarin Basin Synthesis\n78\n170\n175\nTHC\n61\n59\n59\n57\n55\n53\n53\nFIGURE 7.1-Summer - dis-\ntribution of seabirds in the\n51\nBering Sea. (Adapted from\n17C\n165\n160\n180\n175\nShuntov 1972.)\n175\n175°\n170°\n175°\n180\nO\n63°\n63°\n61\n61\nO\nShelf\nSt. Matthew\nIsland\n59\n59\nSlope\nOceanic\n50\n0\n100\n200 km\n57°\nFIGURE 7.2 2-Marine - do-\n57°\nmains of the Navarin\n50\n0\n50\n100 mi\nBasin: oceanic, slope,\nshelf, and St. Matthew\n180°\n175°\n170°\n175°\nIsland. (Adapted from\nHunt 1982.)","Marine Birds\n79\nOceanic\n12 May-10 June\n50\n20 July-18 August\n30\n10\n50\nSlope\n30\n10\n50\nShelf\n30\n10\n50\nSt. Matthew\nIsland\n30\n10\n50\nAll Regions\n30\n10\n0\n0.1-5\n5.1-15\n15.1-30\n30.1-75\n75.1-250\n> 250\nDensity Ranges\nFIGURE 7.3-Density distribution of all birds in the marine domains of the Navarin Basin. (Adapted from Hunt 1982.)\nare among the most vulnerable to spilled oil.\nthe Navarin Basin were made only six times in\nSurveys during winter in the marginal ice zone\n4 years spanning the period 16 February-9 June\n(MIZ) and in the consolidated pack ice in and near\n(Divoky In prep.). Sampling during most transects","Navarin Basin Synthesis\n80\nFIGURE 7.4-Spring distri-\n175°\n170°\n175°\no\n180°\nbution of pelagic birds,\nNavarin Basin vicinity.\n(Adapted from Hunt et al.\n50\n0\n100\n200 km\n63°\n1981c.)\n63°\n50\n0\n50\n100 mi\n61°\n61\n59\n59\nM\nA\nA\nPelagic Distribution\n(birds/km2):\nA\n0\nM\n57\n0.1 15.0\nA\n57'\n15. 1-75.0\nM\n> 75.0\nM\nM\nSpecies with densities of\n180°\n175°\n175°\n170°\no\n15.1 or more birds/km2:\nF - Northern Fulmar\nS - Shearwaters\nP - Storm-petrels\n175°\n180°\n170°\n175°\nK - Black-legged Kittiwakes\nM - Murres\nA - Small auklets\nA\n50\n0\n100\n200 km\n63°\nO\n63°\n50\n0\n50\n100 mi\n3\n61\n61°\nM\n50\nM\nM\n59\nS\nS\n59\nS\nFp\nF\nF\nM\nM\nF\n57\nO\nP\nFIGURE 7.5-Summer dis-\no\n57\nM\nS\ntribution of pelagic birds,\nNavarin Basin vicinity.\nF\nPFS\nF\n(Adapted from Hunt et al.\n180°\n175°\n175°\n170°\n1981c.)","Marine Birds\n81\n175°\n175°\n180\n170°\nS\nA\nA\n50\n0\n100\n200 km\nS\n63\nO\n63\nM\n50\n0\n50\n100 mi\n61°\n61\n59\n59\nM\n57\nP\nFIGURE 7.6-Fall distri-\n57\nbution of pelagic birds,\nNavarin Basin vicinity.\n(Adapted from Hunt et al.\n175\n180 O\n175°\n170°\n1981c.)\nwas opportunistic as vessels were traveling to\nin the Navarin Basin area as they are in the south-\noceanographic stations, and was not done on a\neastern Bering Sea (Divoky In prep.). Typical\ngrid or transect pattern designed to examine bird\nlocations and densities for the more abundant\ndistributions. For this reason the data give an\nspecies in the southeastern Bering Sea are given\nindication of trends in seabird density and distribu-\nin Figure 7.7 The following are average densities\ntion, but function primarily as gross indicators of\nof seabirds regularly encountered at the Bering\nspecies present (G. Divoky pers. commun.).\nSea ice front in March (Divoky 1981):\nThe winter pelagic survey data indicate that the\nSpecies\nBirds/km2\nMIZ and leads within the consolidated pack ice\nNorthern Fulmar\n5\nare probably as important as habitat for seabirds\nGlaucous Gull\n5\nGlaucous-winged Gull\n10\nIvory Gull\n5\nBlack-legged Kittiwake\n10\nTABLE 7.1 -Mean density of birds in the Navarin Basin\nMurres\n200\nby domain.\nBlack Guillemot\n< 5\nMurres are the most abundant species in the MIZ\nDomain\n12 May-10 June\n20 July-18 Aug.\nof the Bering Sea. Divoky (1979) reported feeding\nOceanic\n6 +\n5\n(52)\n7 +\n5\n(50)\nflocks of 25,000 murres in which densities were\nSlope\n27 + 37\n(59)\n19 + 56 (123)\nas high as 10,000 birds/km². Densities of over 500\nShelf\n96 + 323 (322)\n21 + 19 (149)\nmurres/km² were regularly encountered in the\nSt. Matthew I.\n16 + 9\n(26)\n103 + 135\n(83)\nNavarin Basin area in March 1977.\nAll domains\n65 + 175 (459)\n36 + 77 (405)\nThe MIZ is also important habitat for Ivory Gulls\nSOURCE: Hunt 1982.\n(Pagophila eburnea), an uncommon arctic","Navarin Basin Synthesis\n82\nDeep Pack\nIce Front\nOpen Water\nNorthern Fulmar\nBlack-legged Kittiwake\nGlaucous Gull\nGlaucous-winged Gull\nIvory Gull\nMurres\nBlack Guillemot\nFIGURE 7.7-Marine birds along the Bering Sea ice front. (Adapted from Divoky 1981.)\n7.4), or about 60% of the breeding birds of the\nbreeding species. Although average densities are\neastern Bering Sea, breed on these islands. The\nnot high, about 1 bird/km2 (Divoky In prep.),\nsame species breed along the nearby coast of the\nflocks of 10-100 have been encountered in the\nSoviet Union, but the size, location, and composi-\nice near St. Matthew Island in March and April\ntion of colonies there have not been reported.\n(Irving et al. 1970; Divoky In prep.).\nThese colonies consist of two distinct com-\nPolynyas at St. Lawrence Island and St. Matthew\nmunities of marine birds distinguished by type of\nIsland are important winter habitat for murres and\nfood and nesting habitat (Hunt et al. 1981b). One\nsea ducks. Murres are abundant in polynyas at\ncommunity is composed of talus-nesting, zoo-\nboth islands (McRoy et al. 1971; F. Fay pers.\nplanktivorous species, of which Least (Aethia\ncommun.), but numbers have not been quantified.\npusilla) and Crested (A. cristatella) Auklets are the\nFay (1961) estimated that approximately 500,000\nmost numerous species; the other comprises cliff-\nOldsquaws (Clangula hyemalis) and 50,000 eiders\nnesting, fish-eating species, of which murres are\n(Somateria spectabilis and S. mollissima) winter\nthe most numerous species. The colonies on the\nin the polynya at St. Lawrence Island. Oldsquaws,\nPribilof Islands and St. Matthew Island have about\neiders, and Harlequin Ducks (Histrionicus\nequal numbers of the two types of species, while\nhistrionicus) are numerous in the polynya at St.\nthose on St. Lawrence Island are composed mainly\nMatthew (McRoy et al. 1971; Divoky In prep.).\nof the talus-nesting, zooplanktivorous species.\n7.2 BREEDING COLONIES\nNorthern Fulmar\nNorthern Fulmars (Fulmarus glacialis) breed on\nThree of the most important marine bird\ncliffs, on upper vegetated areas on predator-free\nbreeding areas in the eastern Bering Sea-the\nislands, and on rocky ledges of vertical areas when\nPribilof Islands, St. Matthew Island, and St.\npredators are present. They feed at or near the\nLawrence Island (Fig. 7.8)-lie east of the Navarin\nsurface of the water (Ainley and Sanger 1979) on\nBasin planning unit. At least 6 million birds (Table","Marine Birds\n83\ncephalopods, walleye pollock, other fishes, jelly-\nthe eastern Bering Sea cormorant population.\nfishes, and offal. Since much of their food is ob-\nGlaucous Gull\ntained from fishing operations, natural diets are\npoorly known (Hunt et al. 1981a). They lay a single\nGlaucous Gulls (Larus hyperboreus) nest on cliffs\negg, which is incubated for about 47 to 48 days;\nand on the ground. They prey on the eggs and\nyoung remain in the nest for about 53 days.\nyoung of other birds, forage on human garbage,\nThe entire eastern Bering Sea breeding popula-\nand eat a variety of natural prey. Mean clutch size\ntion north of the Aleutians, approximately 35%\nvaries from year to year, but is usually 1-3 eggs.\nof the Alaska population, breeds on the colonies\nGlaucous Gulls are not numerous on the eastern\nmentioned above, mostly on St. Matthew Island.\nBering sea islands.\nCormorants\nBlack-legged Kittiwake\nTwo species, the Pelagic Cormorant\nBlack-legged Kittiwakes (Rissa tridactyla) nest\n(Phalacrocorax pelagicus) and the Red-faced\non small ledges on vertical cliffs. They feed most-\nCormorant (P. urile), breed in this area. They nest\nly on the surface, where they take fishes (mostly\non cliffs, feed by diving and capturing their prey\nwalleye pollock, followed by capelin and myctoph-\nunderwater, and eat mainly fish, especially cottids\nids) and crustaceans (amphipods and euphausiids).\nand crustaceans. Cormorants lay from one to five\nThey may forage as far as 100 km from their col-\neggs, which are incubated about 30 days; young\nonies. In the Bering Sea, they return to occupy\nremain in the nest for about 50 to 60 days.\ntheir colonies between late April and mid-May.\nCormorants form only a small part of the eastern\nIncubation takes an average of 27 days, and chicks\nBering Sea colonies. The Pelagic Cormorant\nremain in the nest for 42 to 44 days. Hatching\nranges farther north than the Red-faced Cormor-\ntakes place from mid-July to mid-August. Black-\nant, but the Red-faced is more abundant. The\nlegged Kittiwakes usually lay one or two eggs.\nislands under consideration support about 30% of\nAbout 30% of the eastern Bering Sea breeding\nTABLE 7.2-Bird density indices (birds/km2) for seasons and habitats in the eastern Bering Sea.\nWinter*\nSpring\nSummer\nFall\nCS\nSB\nOC\nCS\nSB\nOC\nCS\nSB\nOC\nCS\nSB\nOC\nFulmar\n1\n3\n2\n3\n11\n2\n3\n16\n3\n12\n35t\n9\nShearwaters\n0\n0\n0\n3\n3\n+1\n81+\n13\n3\n35\n104\n2\nStorm-petrels\n0\n3\n1\n1\n2\n2\n2\n7\n2\n1\n6\n3\nLarus gulls\n1\n1\n2\n1\n1\n1\n1\n2\n+\n+\n+\n+\nKittiwakes\n1\n1\n2\n1\n2\n2\n1\n3\n5\n1\n+\n+\nAlcids\n16\n2\n2\n34\n20\n5\n15\n17\n2\n9\n3\n2\nMurres\n14\n0\n0\n19\n2\n1\n9\n1\n4\n1\n+\n+\nTufted Puffin\n0\n0\n0\n1\n1\n1\n1\n2\n1\n2\n1\n+\n-\nTotal birds*\n31\n9\n7\n56\n41\n12\n109+\n58\n11\n65\n157+\n16\nTotal birds# minus\nshearwaters\nand Fulmars\n30\n6\n5\n50\n27\n10\n25\n29\n5\n18\n18\n4\nSOURCE: Hunt et al. 1981c.\nNOTE: Data are derived from combined ship and air surveys. Habitats include continental shelf (CS), shelf break (SB). and\noceanic (OC) waters.\nBased on a single aerial survey and no shipboard surveys.\nt These densities are highly biased from sightings of large flocks.\n+ All densities have been rounded to nearest whole number: \"+\" indicates <0.5 birds/km2.\nAll species sighted: includes waterfowl, shorebirds, others.","Navarin Basin Synthesis\n84\n169°30'\n173°\n172°\n170°30'\n5\n6\nST. MATTHEW\nSt. Paul Island\nISLAND\nWairus Island\nI\n60°\n60'\nO\n7\n45'\n45'\n19\nHall Island\n8\n2\nOtter Island\n-\n9\n57°\n57°\n.10\n11\n3\n18\n4\n17\nSt. George\n60°\n60°\no\n16\nIsland\n15'\n15'\nPinnacle Island\n15\n12\n56°\n56°\n14\n3\nPRIBILOF ISLANDS\n30'\n30'\n169°30'\n173°\n172°\n170°30'\n172°\n171°\n170°\n169°\nNUMBER OF BIRDS\ni\n23\n20\n22\n21\nUnknown\n<501\n24\n501-5.000\nStolbi Rocks\n5,001-50,000\n50,001-500,000\n63°\n63°\n30'\n30'\n> 500,000\n26\n25\nPunuk\n63°\n63°\nIslands\nST. LAWRENCE ISLAND\n172°\n171°\n170°\n169°\nFIGURE 7.8-Distribution of seabird colonies on the eastern Bering Sea shelf-edge islands.\n(Data source: Sowls et al. 1978.)\nby an overhang. They are surface feeders and\npopulation nest on the Pribilofs, St. Matthew, and\nspecialize on myctophids, which are deepwater\nSt. Lawrence.\nfishes. They lay a single egg during the second\nRed-legged Kittiwake\nhalf of June. Incubation takes about 29 days, and\nchicks are in the nest for about 37 days.\nRed-legged Kittiwakes (R. brevirostris) nest on\nRed-legged Kittiwakes are endemic to the Ber-\ncliffs; they seem to prefer ledges that are sheltered","Marine Birds\n85\ning Sea. They breed only on the Pribilofs, on Buldir\nmost important in other areas. Thick-billed Murres\nand Bogoslof islands in the Aleutian Chain, and\narrive in the area of their breeding colonies in\non the Komandorsky Islands. About 88% of the\nApril. The single egg is usually laid in July. Incuba-\nworld's population nest on St. George Island\ntion takes about 34 days, and the chicks leave the\n(Hickey and Craighead 1977).\nledges about 21 days after hatching.\nThick-billed Murres are probably the most abun-\nCommon Murre\ndant marine bird breeding in the Bering Sea.\nCommon Murres nest on broad cliff ledges and\nAbout 95% of the eastern Bering Sea breeding\non the tops of flat, rocky, predator-free islands.\npopulation is found on the island colonies.\nThey feed by diving. Around the Pribilofs, their\nPigeon Guillemot\nsummer diet is almost exclusively fishes, walleye\npollock being the most important species. Inverte-\nPigeon Guillemots (Cepphus columba) nest in\nbrates may be important prey in the winter. On\nnatural crevices in talus slopes at the base of rocky\nthe Pribilofs, the single egg is laid on the first week\ncliffs. They forage for fishes in shallow waters near\nof July. Incubation takes about 31 days, and the\nthe shore, lay two eggs, which are incubated about\nflightless chicks leave the ledges about 21 days\n30 days, and their young leave the nest about 35\nafter hatching.\ndays after hatching.\nThe island colonies support only about 14% of\nPigeon Guillemots are numerous in the Bering\nthe eastern Bering Sea breeding population of\nSea. None nest in the Pribilofs, but approximate-\nCommon Murres. Most of these are found on the\nly 10% of the Alaska population is on St. Matthew\nPribilof Islands.\nIsland and St. Lawrence Island.\nThick-billed Murre\nParakeet Auklet\nThick-billed Murres nest on narrow ledges of\nParakeet Auklets (Cyclorrhynchus psittacula)\nseacliffs and on the tops of low, predator-free\nnest in natural crevices in cliffs, talus slopes, and\nislands. During the breeding season, their main\nboulder beaches. They take a wide variety of mid-\nprey is fishes, but unlike the diet of Common\nwater and epibenthic food, including amphipods,\nMurres, invertebrates are also important prey.\neuphausiids, and larval fishes. They lay a single\nAmphipods are most important on the Pribilofs,\negg, incubation lasts about 35 days, and the young\nbut other invertebrates have been reported as\nleave the nest about 35 days after hatching.\nTABLE .3-Transects with more than 100 birds, Navarin Basin.\nTransects\nPredominant\nPredominant Flight\nDates\nDomain\n(N)\nSpecies\nDirection, Behavior\n12 May-10 June\nOceanic\n0\n-\n-\nSlope\n3\nFork-tailed Storm-petrel\nSouth\n1\nRed Phalarope\nN, NE\nShelf\n17\nLeast Auklet\nN, NE, E, on the water\n17\nFork-tailed Storm-petrel\nNot determined, on the water\n9\nRed Phalarope\nW, NW\nSt. Matthew I.\n0\n-\n-\n=\n20 July-18 Aug.\nOceanic\n0\n-\n-\nSlope\n4\nFork-tailed Storm-petrel\nShip influenced. on the water\nShelf\n0\n-\n-\nSt. Matthew I.\n22\nMurres\nW. NW, N, NE\n6\nLeast Auklet\nNot determined, on the water\nSOURCE: Hunt 1982.","Navarin Basin Synthesis\n86\nthe nest after about 34 days.\nAbout 75% of the eastern Bering Sea breeding\nThis species is endemic to the Bering Sea. The\npopulation nest on the island colonies.\nisland colonies support 80% of the eastern Bering\nCrested Auklet\nSea breeding population.\nCrested Auklets nest in coastal areas in natural\nLeast Auklet\ntunnels and crevices and inland in talus. They eat\nLeast Auklets nest in natural crevices in cliffs,\nmainly euphausiids, amphipods, and copepods, the\ntalus slopes, and boulder piles. They eat mainly\nrelative amounts of which may differ between\ncalanoid copepods and amphipods. The single egg\nlocations and seasons. They lay one egg. incuba-\nis laid in mid- to late June. Incubation takes about\ntion averages about 35 days, and the chicks leave\nTABLE 7.4-Breeding bird colonies, eastern Bering Sea shelf edge.\nBlack-\nRed-\nPigeon\nGlau-\nlegged\nlegged\nNorth-\nKitti-\nKitti-\nGuille-\nColony\nCormo-\ncous\nern\nAuklets\nPuffins\nTotal\nwake\nMurres\nDucks\nGull\nwake\nmot\nNumber\nFulmar\nrants\n2,788,300\nPribilof Is.\n300\n300\n1\n-\n-\n-\n-\n-\n-\n-\n63,000\n5,400\n253,800\n31,000\n2,200\n149,000\n2\n700\n2,500\n-\n-\n15,200\n5,000\nX\n3\n200\nx*\n10,000\n-\n-\n-\n428,000\n34,000\n2,519,000\n72,000\n220,000\n1,690,000\n70,000\n5,000\n4\n-\n-\n-\n1,444,570\nSt. Matthew I.\n4,020\n658,107\n40,450\n340,000\n1,200\n46,900\n5\n224,000\n1,000\n37\n500\n-\n35,000\n190\n35,300\n1,600\n97,280\n20\n2,000\n06\n23,000\n150\n20\n-\n12,500\n100\n50\n230\n14,691\n180\n1,540\n07\n50\n41\n-\n2,000\n110\n27,000\n300\n30,270\n40\n800\n08\n20\n-\n-\n370\n50\n150\n200\n778\n8\n09\n-\n-\n-\n-\n100\n1,935\n30\n15\n270\n1,500\n20\n10\n-\n-\n-\n330\n19,090\n7,000\n8,800\n100\n2,400\n11\n400\n60\n-\n-\n80,000\n300\n53,400\n2,800\n177,767\n67\n6,000\n12\n35,000\n200\n-\n-\n4,916\n60\n1,200\n2\n70\n500\n13\n3,000\n84\n-\n-\n-\n10\n1,016\n14\n6\n1,000\n-\n-\n-\n-\n-\n-\n-\n2,600\n200\n39,700\n210\n58,475\n15\n14,000\n200\n45\n20\n1,500\n-\n154,000\n150\n750\n3,000\n50,000\n16\n100,000\n60\n40\n-\n-\n-\n100\n7,530\n5,100\n60\n60\n20\n17\n2,000\n180\n10\n-\n-\n2,000\n160\n100\n450\n7,420\n18\n4,000\n300\n30\n30\n350\n-\n300\n98,000\n700\n211,295\n19\n44,550\n710\n17\n18\n7,000\n60,000\n-\n1,874.110\nSt. Lawrence I.\n185,000\n2,000\n187,000\n20\nX\nX\nX\n-\n-\n-\n-\n72,000+\n300\n22,000\n101,300\n7,000\nX\n21\nx\nX\n-\n-\n4,000\n85,000\n90,000\n22\nX\n-\n-\n-\n15,000\n631,000\n646.500\n500\n23\nX\n-\n-\n2,000\n5,000\n57,000\n64.080\n24\n80\n-\n-\n-\n205,000\n509,000\n714,000\n25\nX\nX\n-\n-\n-\n1,350\n72.230\n1,800\n34,000\n150\n34,600\n26\n300\n30\n-\n-\n2,784,670\n3,450\n2,317,600\n55,750\n6.106.980\nTotal:\n520,700\n11,080\n200\n2,030\n189,300\n222,200\nSOURCE: Sowls et al. 1978.\n*\nX = Present.\nt Murre numbers for St. Lawrence Island are from Springer et al. (1983).","Marine Birds\n87\nobserved migrants in the area are Red-throated\n31 days, and the young fledge at about 29 days.\nLoons, Snow Geese (Chen caerulescens), Northern\nThese birds are endemic to the Bering Sea and\nPintails, Greater Scaups (Aythya marila), and\ntheir colonies are among the largest in the area.\nAbout 60% of the eastern Bering Sea breeding\nCommon Eiders.\nDuring the open-water season Harlequin Ducks,\npopulation is found on the island colonies.\nOldsquaws, King Eiders (Somateria spectabilis),\nHorned Puffin\nand Common Eiders are present in the vicinity of\nthe islands. In winter the polynyas near the islands\nHorned Puffins (Fratercula corniculata) nest in\nare used by King and Common Eiders, Harlequin\nnatural crevices in cliffs, talus, and boulder rubble.\nDucks, and Oldsquaws. It is also possible that Spec-\nThey dive for their food, usually in shallow water\ntacled Eiders (Somateria fischeri) may be present:\nnear the breeding colonies. The major foods dur-\nbut this supposition has not yet been verified.\ning the breeding season appear to be shallow-\nTwenty-two species of waterfowl have been\nwater fishes and a variety of invertebrates. The\nrecorded from St. Lawrence Island (Fay 1961). Of\nsingle egg is laid in mid-June to early July. Incuba-\nthese, 10 species are only of accidental or irregular\ntion takes about 40 days, and the young fledge\noccurrence, whereas 12 species are known or\nat about 6 weeks.\nthought to breed there. For most of these species,\nThese birds are only moderately abundant in\nthe island is not particularly important for the\nthe Bering Sea. About half of the eastern Bering\nBering Sea populations. For others, it is an impor-\nSea breeding population is found on the island\ntant wintering or staging area.\ncolonies.\nThe most abundant summering species is the\nTufted Puffin\nEmperor Goose (Philacte canagica). Between\n10,000 and 20,000 nonbreeding birds spend the\nTufted Puffins (Lunda cirrhata) excavate bur-\nsummer along the southern coast of St. Lawrence\nrows in grassy slopes of predator-free islands or\nIsland or on some of the larger lagoons along the\nnear the tops of cliffs. They forage farther from\nnorthern coast (Fay 1961). These are joined by\nthe breeding colonies than do Horned Puffins.\nfailed breeders from the United States and possibly\nTheir diet is mostly fishes (about half walleye\nthe Soviet mainland which have a well-defined\npollock), supplemented by polychaete or nereid\nmolt migration to St. Lawrence Island (Jones 1972).\nworms. Incubation takes about 45 days, and the\nFay reported large numbers of flightless Emperor\nyoung fledge at about 45 days.\nGeese present on the island from about mid-June\nPopulations of Tufted Puffins in the eastern\nto mid-August. Fay and Cade (1959) suggested that\nBering Sea are considerably smaller than the\nthe entire immature population of Emperor Geese\nAleutian and Gulf of Alaska populations. The island\ncolonies support about 10% of the eastern Bering\nsummers on St. Lawrence.\nFew Snow Geese nest in Alaska; all those that\nSea breeding population.\npass through the Bering Sea in migration nest on\nWrangel Island, U.S.S.R., and winter in California.\n7.3 WATERFOWL\nSt. Lawrence Island is one of their important\nresting places during fall migration (King and Dau\nThe waterfowl usage of the Navarin Basin and\n1981). They move through the island in small flocks\nadjacent areas has been only little studied; most\nfrom late August to late September (Fay 1961).\ninformation comes from recent surveys by Hunt\nDuring the winter about 50,000 Common and\n(1982), Sowls et al. (In prep.), and Divoky (In prep.).\nKing Eiders and 100,000 Oldsquaws are found in\nSowls (pers. commun.) lists 29 species of water-\nthe ice-free areas about St. Lawrence. Most of the\nfowl in the St. Matthew Island area, along with 4\nwintering Oldsquaws arrive in December and re-\nspecies of loons and 1 grebe. Oldsquaw, Red-\nmain until the middle or end of April (Fay 1961).\nthroated Loon (Gavia stellata), Northern Pintail\nSpectacled Eiders have not been reported in\n(Anas acuta), and Common Eider (Somateria\nnumbers in the Bering Sea in winter, but in May\nmollissima) are known nesting species, but\n1980 many thousands were observed migrating\nnumbers are low-probably due to the high num-\nfrom west to east across the Navarin Basin (F. Fay\nber of arctic foxes present. The most frequently","Navarin Basin Synthesis\n88\npers. commun.).\nThe decline in reproductive success contrasts\nwith the uniform, moderate level of success dur-\n7.4 SHOREBIRDS AND TERRESTRIAL BIRDS\ning 1975-79 on the Pribilofs (Hunt et al. 1981b).\nThe tendency toward stability resulted from the\nTwenty-three shorebird species are included\nhighly productive food web of the outer shelf zone\namong the 123 species of birds that have been\n(see Iverson et al. 1979) that provided a regular\nrecorded in the St. Matthew Island area (A. L. Sowls\nand adequate supply of prey. However,\npers. commun.). Rock Sandpipers (Calidris\ncharacteristics of the breeding failure in 1981 and\nptilocnemis) and Red-necked Phalaropes\n1982 were symptomatic of food shortage: few nests\n(Phalaropus lobatus) are the only common\nwere built, few eggs were laid, and a large pro-\nbreeders. Migrant shorebirds frequently observed\nportion of the chicks that hatched died. Prey taken\nin spring include Lesser Golden Plovers (Pluvialis\nin 1982 by murres, kittiwakes, puffins, and guille-\ndominica), Dunlins (Calidris alpina), Red\nmots on St. Matthew Island consisted of relatively\nPhalaropes (Phalaropus fulicarius), and Red-\nlarge numbers of invertebrates and small numbers\nnecked Phalaropes.\nof fishes (Springer et al. 1983). Because pollock\nTwenty-nine terrestrial bird species have been\nare thought to be the principal prey of murres and\nobserved. One, McKay's Bunting (Plectrophenax\nBlack-legged Kittiwakes, and important prey of\nhyperboreus), is an endemic breeder on the St.\nRed-legged Kittiwakes (Hunt et al. 1981a), it is\nMatthew Island group. Other common breeding\nassumed that the birds have been unable to ob-\nspecies are the Lapland Longspur (Calcarius\ntain sufficient numbers of pollock or a suitable\nlapponicus) and Gray-crowned Rosy Finch (Leuco-\nalternative in the past 2 years. This assumption is\nsticte tephrocotis). Spring migrants include the\nsupported by hydroacoustic surveys in the eastern\nSandhill Crane (Grus canadensis) as well as several\nBering Sea which detected fewer than 15% as\nEurasian species stopping over while en route to\nmany age classes 1 and 2 pollock in 1982 as in\nmainland Alaska breeding areas. Fall migration\n1979 (J. Traynor pers. commun.).\nand winter usage of the St. Matthew Island area\nIn northern Alaska, the reproductive success of\nby birds has not been investigated in any detail.\nmurres and kittiwakes is highly variable and\ndepends upon prey availability. Available prey\n7.5 STATUS OF SEABIRD POPULATIONS\nbiomass varies significantly between years, in\nparallel with temperature changes in the marine\nLittle is known about trends in numbers or in\nenvironment; prey biomass and reproductive suc-\nreproductive success of many species of seabirds\ncess of the birds are low in cold years and high\nbreeding on islands in the Bering Sea. Important\nin warm years (Springer et al. In press). Similarly,\nexceptions are the data on murres and kittiwakes,\nnumbers of adult kittiwakes at breeding colonies\nwhich document recent decreases in numbers of\nare lower in poor years and higher in good years.\nmurres and reproductive success of murres and\nIn contrast, the numbers of murres at two north-\nkittiwakes on the Pribilof Islands and on St.\nern colonies, Bluff in Norton Sound and Cape\nMatthew Island.\nThompson in the eastern Chukchi Sea, have de-\nBlack-legged Kittiwakes on St. Matthew Island\nclined steadily since the mid-1970's (Springer et\nexperienced very poor reproductive success in\nal. 1983). Moreover, murres were only half as\n1982 and 1983 (Springer et al. In press; Springer\nnumerous at Cape Thompson in 1976 as in 1960\net al. In prep.), as did both species of kittiwake on\nwhen they were first censused (Swartz 1966). A\nthe Pribilof Islands in 1981 and 1982 (D. Lloyd un-\nnumerical population analysis, based on temper-\npubl. data; Craighead and Oppenheim In press).\nature, reproductive success, and other population\nReproductive success was low in all years. Murre\nparameters indicated that murre numbers at Bluff\nnumbers on St. Matthew Island in 1982 and 1983\ncould decline because of reduced natality associ-\nwere about half as large as in 1977. Thick-billed\nated with cooler environmental conditions during\nMurre numbers were lower by about 20% and 50%\nthe past 15 years.\non St. George Island and St. Paul Island, respec-\nIt is not known if the changes in murre numbers\ntively, in 1982 as compared to 1976 (Craighead and\non the Pribilofs and St. Matthew Island represent\nOppenheim In press).\ntrends in declining populations such as at Bluff and","Marine Birds\n89\nBering Sea. The prey of murres and kittiwakes in\nCape\nompson, or if the changes are only temp-\nresponses to the unusually poor food avail-\nthe Navarin area is chiefly walleye pollock, a\norary\nthe past 2 years. In 1976, an extremely\nspecies that sustains an immense biomass of\nability\noductive year in northern Alaska, murre\nmarine vertebrates including other fishes, seabirds,\nbad repr\nnumbers at the Owalit Mountain colony on St.\npinnipeds, and cetaceans, as well as the largest\nLawrence Island were only half as as great as in\nsingle-species commercial fishery in the North\n1972 and 1981, both good reproductive years.\nPacific Ocean. The effects on pollock biomass of\nPrey populations of murres and kittiwakes\nclimatic factors and the combined catch by pred-\nfluctuate between years in northern Alaska, ap-\nators and the commercial fishery are unknown;\nparently in response to fluctuating climatic events\nhowever, estimates of pollock biomass since 1973\nthat influence the marine environment. Similar\nhave been about 50-75% lower than during the\nrelationships between the physical environment\nlate 1960's when the fishery was developing\nand prey populations could exist in the southern\n(Bakkala and Wespestad 1982).","","Chapter 8.\nMarine Mammals\nJOSEPH G. STRAUCH, JR.\nScience Applications, Inc., Boulder, Colorado\nMarine mammals inhabit the Navarin Basin\nthe Arctic Ocean with the onset of inhospitable\nthroughout the year, although the abundance of\nheavy ice conditions to the less rigorous ice en-\nmost species varies seasonally. Six baleen (mysti-\nvironments in the Bering Sea. Ice confers certain\ncete) and six toothed (odontocete) whale species\nbenefits to these groups: (1) isolation from predators\nhave been observed or likely occur in this portion\nand disturbance; (2) space for animals to distribute\nof the Bering Sea. The sperm whale (Physeter\nthemselves for various activities; (3) a means of\ncatodon) and all the baleen whales, except the\npassive transportation; (4) proximity to food sup-\nminke (Balaenoptera acutorostrata), are listed as\nplies; (5) facilitated sanitation, as a consequence\nendangered under the 1973 Endangered Species\nof increased space between animals; and (6) shelter\nAct as amended. Four hair (phocid) seals, two eared\nfrom the weather, in the form of ice irregularities\n(otarid) seals, and the walrus (Odobenus rosmarus)\nor accumulated snow (Burns et al. 1981a, 1981b).\nare found within the area; a fifth phocid, the harbor\nThe species exploit different ecological niches, so\nseal (Phoca vitulina richardsi), is found just out-\nthey tend to partition their environment in a pre-\nside of the area at the Pribilof Islands. All of these\ndictable manner. In short, each species prefers ice\nspecies feed in the Navarin Basin during one or\nhabitats it can cope with in order to carry out life\nmore seasons of the year.\nactivities. Further, the required ice conditions must\nThe spatial and temporal distributions of marine\noccur in a dependable and timely fashion.\nmammals in the Navarin Basin are markedly\nWater depth is a passive but important constraint\ninfluenced by environmental factors. Chief among\non habitat use for several marine mammal species\nthese are seasonal sea ice, availability of prey, and\nin the Bering Sea. Due to availability of prey or\nwater depth. Relatively few marine mammal\nphysiological limitations, some species are found\nspecies reside year round in the basin; the bulk\nmainly in deep waters, while others are usually\nare found either during the open-water period or\npresent over the continental shelf. Sperm whales\nwhen ice cover is present-a reflection of their\nexemplify the former group, while gray whales,\nhabitat preferences. Thus, the summer residents\nwalruses, and bearded seals are among the latter.\ntypify the more temperate boreal regime, and the\nThe primary information sources for this chapter\nwinter residents the arctic.\nare: (1) sighting information through about 1980\nIn the spring, as the sea ice recedes northward\nobtained from NOAA's Platforms of Opportunity\na number of marine mammal species migrate into\nProgram, (2) data and reports resulting from a\nthe northern Bering Sea to feed and carry out\nnumber of OCSEAP-sponsored studies in the\nother activities. Gray whales are perhaps the best\nNavarin Basin and nearby waters during 1975-83,\nknown of this group. Other species include fur seals\nand (3) data from the Alaska Department of Fish\nand sperm whales.\nand Game and National Marine Fisheries Service.\nDuring winter, ice-associated pinnipeds and\nInformation from a variety of other published and\ncetaceans predominate. Strongly ice-associated\nunpublished documents is included where appro-\nmarine mammals include the bowhead whale,\npriate. The reader is referred to the following\nbelukha whale, ringed seal, bearded seal, ribbon\ndocuments for additional information on marine\nseal, and spotted seal. They move southward from\nmammals of the Bering Sea: Braham et al. (1980),\n91","Navarin Basin Synthesis\n92\nBering Strait as the ice breaks up and follow leads\nHood and Calder (1981). Morris (1981), Norton and\nalong the Alaska coast to Point Barrow, where they\nSackinger (1981), Hameedi (1982), Leatherwood et\nmove east into the Beaufort Sea to feed primarily\nal. (1982), Zimmerman (1982), Frost et al. (1983),\non euphausiids, copepods, and amphipods during\nSeveringhaus (1983), and Thorsteinson (1984).\nsummer (Lowry and Burns 1980). Present day bow-\nhead stocks apparently vacate the eastern Bering\n8.1 CETACEANS\nSea during summer (Dalheim et al. 1980). Recent\n8.1.1 Baleen Whales\nsightings of bowheads have been immediately\nadjacent to the Navarin Basin to the east,\nBaleen whales feed by filtering animals out of\nsoutheast, and north (Fig. 8.1).\nthe water or bottom sediments. Most baleen whale\nA lesser known species, the North Pacific right\nspecies build blubber reserves in high latitudes\nwhale (Eubalaena glacialis), was taken by whalers\nduring summer months when primary productivity\na century ago in this area, but is extremely rare.\nis high. In winter, these species move to lower\nThe right whale's current northern limit in the\nlatitudes to calve in warmer areas, which are\nBering Sea is thought by Berzin and Doroshenko\npresumably more favorable (by reducing heat loss)\n(1982) to be south of a line joining Atka, St.\nto small calves and adults despite the greatly\nMatthew, and Nunivak islands. The right whale and\nreduced food resources (Laws 1977). Baleen whales\nperhaps the bowhead whale appear not to have\nare found in areas where prey are annually abun-\nincreased in numbers since cessation of com-\ndant (Nemoto 1957). Nemoto (1970) has reviewed\nmercial hunting. During the summer of 1982\nseveral different feeding strategies for baleen\nBrueggeman (1983) sighted two right whales over\nwhales. In general, all baleen whales eat inverte-\nthe continental shelf west of St. Matthew Island.\nbrates where they are abundant and some eat\nThis was one of very few sightings of the species\nschooling fishes.\nin Alaskan waters in the past 20 years.\nBowhead whales. (Balaena mysticetus) were\nMinke whales are worldwide in distribution.\nhunted extensively in the Bering and Chukchi seas\nThey are found around 25° N. in the North Pacific\nfrom the mid-19th century into the early 20th\nduring winter months and throughout the Bering\ncentury. The population has now been reduced to\nSea and in the southern Chukchi Sea in summer\napproximately 2,200-4,000 (Braham et al. 1979;\nmonths (Braham et al. 1977). Recent surveys by\nDronenburg et al. 1982) from a pre-exploitation\nBrueggeman (1983) demonstrate that some minke\npopulation of between 14,000 and 30,843 (Mitchell\nwhales are present in the Navarin Basin during\n1977; Bockstoce and Botkin 1980; Breiwick et al.\nwinter. In the North Pacific, they feed primarily\n1981). A native harvest of this species still occurs\non euphausiids and schooling fishes such as her-\nduring spring and fall migrations.\nring, cods, pollock, sand lance, and capelin\nThere is evidence that bowheads winter in the\n(Nemoto 1970). Minke sightings near or within the\nsouthwestern Bering Sea near the ice front, which\nNavarin Basin are shown in Figure 8.1.\nincludes the Navarin Basin. Brueggeman (1982)\nFin whales (Balaenoptera physalus) are\nfound concentrations of bowheads west of St.\nworldwide in distribution. They migrate from\nMatthew Island as well as west of St. Lawrence\nwintering areas in subtropical latitudes to the\nIsland during surveys of the marginal ice zone and\nBering Sea during summer months, where they\ninterior pack ice in 1979. In 1982-83 he observed\nfeed primarily on euphausiids, copepods, and some\n25 bowhead whales concentrated along the west-\nschooling fishes and squids. Nemoto (1959) report-\nern fringe of a polynya on the southwest side of\ned fin whales attracted to an area southwest of the\nSt. Matthew Island and estimated that about 171\nPribilof Islands due to dense aggregations of\nbowheads wintered in the Navarin Basin during\neuphausiids. Recent sightings of fin whales com-\nthat period (Brueggeman 1983). (No sighting effort\npiled by NMFS are concentrated outside of the\nwas expended in open water or heavy pack ice.)\nNavarin Basin area (Fig. 8.1); however, the apparent\nIt is not known whether bowheads feed in the\ndistributions may be more an artifact of sighting\nNavarin Basin during winter, although animals\neffort than actual distributions. The outer continen-\nseen near St. Matthew Island in March 1979\ntal shelf and slope of the Bering Sea, including the\napparently were feeding (Leatherwood et al. 1982).\nNavarin Basin region, were historic Japanese whal-\nBowheads migrate north in the spring through the","Marine Mammals\n93\n175°\n180°\n175°\n170°\n50\n0\n100\n200 km\nDD\n63°\n63\n50\n0\n50\n100 mi\n61\n61°\nD\n59\n59\nD\nBowhead\n57\nMinke\nFIGURE 8.1 -Sightings of\n57'\nHumpback\nbaleen whales in the\nFin\nNavarin Basin and vicini-\nty. (Data source: NOAA,\n175\n180°\n175°\n170°\nNMFS, unpubl.).\ning grounds for fin whales. Nasu (1974) reports\ncommun. 1981), indicating the extensive annual\nsignificant numbers of the animal in the region.\nmovements by some individuals of this species.\nApparently July was the peak month for captures\nConversely, sighting data have demonstrated that\nof fin whales in the Navarin Basin.\nconsiderable numbers of the animals may over-\nSeasonal surveys by Brueggeman (1983) indicate\nwinter in southeastern Alaska.\nthat the fin whale is the most abundant whale in\nHumpback whales feed in the Bering Sea and\nthe region, being present year round and concen-\nthe southern Chukchi Sea during July, August, and\ntrated over the outer continental shelf. Population\nSeptember (Wolman 1978). Some have been\nestimates developed from the surveys suggested\nsighted in the Navarin Basin during summer\nseasonal abundances ranging from 84 to 259 ani-\nmonths (Fig. 8.1), but the wintering grounds of\nmals in the Navarin Basin in 1982-83. The diet\nthese particular individuals are unknown.\nof this species may consist of copepods, fishes, or\nHumpbacks eat a variety of prey, including\nsquid, depending on prey availability.\neuphausiids, fishes, mysids, and amphipods. but like\nThe North Pacific stock of humpback whales\nother whales may favor only one prey species at\n(Megaptera novaeangliae) numbers less than 1,000\na given time. Bubble-net feeding is a spectacular\nanimals (Leatherwood et al. 1982) and is one of\nhumpback feeding behavior. A whale entraps and\nthree existing stocks. The North Pacific stock was\nconcentrates schooling fishes in an ever decreas-\nreduced in number by commercial harvest during\ning spiral column of air bubbles it releases from\nthe last 100 years from an estimated pre-exploita-\nits blowhole and then lunges to the surface through\ntion size of 15,000 (Wolman 1978). One individual\nthe prey with its mouth agape.\nwhale which fed in southeastern Alaska during one\nPacific gray whales (Eschrichtius robustus) were\nsummer was spotted during different winters in\nhunted to near extinction in the 19th century, but\nHawaiian and Mexican waters (J. Darling pers.\nafter 50 years of protection are now nearly as","94\nNavarin Basin Synthesis\nabundant as before exploitation at approximate-\nregion. However, Japanese whalers captured sei\nly 16,500 animals (Reilly et al. 1979). Gray whales\nwhales in the Bering Sea only rarely (Nasu 1974).\nfeed primarily in the Bering and Chukchi seas dur-\n8.1.2 Toothed Whales\ning summer months. Censuses at Unimak Pass\nindicate some 13,000-15,000 of the animals are\nThe sperm whale is worldwide in distribution.\npresent in those regions from April to December\nThe North Pacific stock numbers about 774,000\n(Rugh and Braham 1979). Although a few whales\n(Rice 1978). Sperm whales do not migrate the same\nmay still migrate south along the Asian Pacific\nway most baleen whales do. They probably move\ncoast, most move to calving areas along the Baja\nseasonally in response to the availability of food,\nCalifornia coast of Mexico via the nearshore waters\nbut do not undergo prolonged fasting. Females are\nof the eastern Pacific Ocean. Gray whales move\nrarely found north of 45° N., while males range\nSO close to shore that they are counted along their\ninto the Bering Sea as far as 61° N. (Rice 1978)\nmigration route to develop population estimates\nand likely occur seasonally in the Navarin Basin.\n(Reilly et al. 1979).\nSperm whales usually feed in deep water, primarily\nThere are few observations of gray whales in the\non squids, including some very large species,\nNavarin Basin. Nasu (1974) indicates that gray\nalthough many species of fishes have also been\nwhales are present in the outer shelf area in the\nreported. Diving sperm whales have been tracked\nvicinity of the basin in early July. According to\nby sonar to depths of 3,193 m (Rice 1978).\nFrost et al.'s (1983) list of sightings of gray whales\nBelukha whales (Delphinapterus leucas) are\nin the St. Matthew Island vicinity, animals were\nsolely arctic and subarctic in their distribution.\nobserved there in June and July 1977, August\nSome belukhas inhabit bays and nearshore waters\n1980, and during the summer of 1982. The first\nduring summer months (Burns et al. 1982; Frost\nmentioned observations indicated instances of\net al. 1983), but most of the 8,000 or more inhabit-\nfeeding less than 1 km from shore. The whales\ning the Bering Sea (Interagency Task Group 1978)\nwere observed frequently in late May and early\nwinter in the central Bering Sea. During the 1979\nJune. Brueggeman (1983) encountered a concen-\nPolar Sea cruise, observers found belukhas in the\ntration of gray whales just northeast of the Navarin\nnorthern Navarin Basin and immediately east of\nBasin (approximately 63° N., 173° W.) in autumn\nthe planning unit (Fig. 8.2). Brueggeman (1983)\n1982.\nsighted over 600 belukha whales in the marginal\nIn the Bering Sea, gray whales feed on dense\nice zone during a winter survey of the Navarin\nconcentrations of benthic amphipods from April\nBasin. The animals were primarily observed west\nthrough November. The best documented trophics\nof St. Matthew Island in areas of thin but exten-\ninformation comes from the northern portion of\nsive ice coverage. No belukhas were sighted by\nthe Bering Sea. Thomson (1983), Johnson et al.\nBrueggeman in the region during spring, summer,\n(1983), and others have studied gray whale feeding\nand fall surveys. However, Leatherwood and Evans\necology in the vicinity of St. Lawrence Island and\n(1982) reported belukhas in the vicinity of St.\nin the Chirikof Basin. The investigations demon-\nMatthew Island in March and May 1982.\nstrated intensive selective feeding on benthic\nIn 1981 the statewide subsistence harvest of\nampeliscid and and corophiid amphipods in those\nbelukha whales was some 180-240 animals (Burns\nareas. On the order of 15% of the total gray whale\net al. 1982).\npopulation was estimated to summer in the St.\nLowry et al. (1979) found that belukha whales\nLawrence Island-Chirikof Basin region. During that\nin Norton and Kotzebue sounds ate mainly saffron\ntime they consume about 10% of the standing crop\ncod, while Brooks et al. (1955) found the diets of\nand 5% of the annual productivity of amphipods\nbelukhas in Bristol Bay consisted primarily of smelt\non the feeding grounds.\nand salmon fingerlings in the spring and adult\nLate summer sightings of blue whales (Balaenop-\nsalmon in summer. The prey species eaten near\ntera musculus) in the vicinity of St. Lawrence Island\nshore may have little resemblance to those taken\nhave occurred in recent years (Leatherwood et al.\noffshore, which are primarily pelagic and\n1982). Thus the species may also be present in low\nsemidemersal fishes and some cephalopods and\nnumbers in the Navarin Basin. Similarly, sei whales\ncrustaceans. Aside from the apparent preference\n(B. borealis) may penetrate northward into the\nfor estuarine habitats of some belukhas in sum-","Marine Mammals\n95\n175\n180\n175°\n170\no\n50\n0\n100\n200 km\n63°\n63\n50\n0\n50\n100 mi\n61\n61\n59\n59\nDall porpoise\n57'\nFIGURE 8.2-Sightings of\nBelukha\n57\nKiller\ntoothed whales in the\nNavarin Basin and vicini-\nty. (Data source: NOAA,\n180°\n175\n175\n170°\nNMFS, unpubl.)\nmer months, much of their distribution is likely\nDuring seasonal surveys in 1982-83, Brueggeman\nrelated to prey availability.\n(1983) encountered the animals during all cruises,\nThe killer whale (Orcinus orca) is distributed\nthus the possibility exists that some animals may\nworldwide. Its northern limit is fast ice and heavy\nbe resident in the area. In spring and fall Brueg-\npack ice. Killer whales inhabit the Bering Sea and\ngeman observed primarily northward and south-\nsouthern Chukchi Sea (Fig. 8.2), but their numbers\nward movements, respectively.\nthere are unknown. They eat virtually any other\nDall porpoises (Phocoenoides dalli) live only in\nmarine mammal, as well as schooling and large\nthe North Pacific Ocean, Bering Sea, and possibly\nfishes, and squids. Fay and Kelly (1980) found\nthe southern Chukchi Sea (Frost and Lowry 1981).\npathological evidence of death due to killer whale\nBraham et al. (1977) reported Dall porpoises were\nattacks in some individuals in the hundreds of\namong the four most commonly sighted cetaceans\nwalruses that died at haulouts on St. Lawrence\n(Fig. 8.2). This species was the most ubiquitous\nIsland in autumn 1978. This species can dive to\ncetacean in the Navarin Basin in 1982-83 (Brueg-\nat least 1,050 m (Scheffer 1978).\ngeman 1983). Dall porpoises swim fast and feed\nKiller whales often stay associated with each\non squid, hake, capelin, and herring. Treacy\nother in social or familial \"pods.\" In Puget Sound\n(quoted in Frost and Lowry 1981) found primarily\n(Washington and British Columbia) some pods\nsquid and secondarily myctophid fishes (91.5% of\nhave been identified from photographs for 10 or\nall fishes) made up the diet of 226 Dall porpoises\nmore years. Close study of these groups has\ncaught incidentally in the Japanese high seas\ndetermined that some pods are only in the sound\ngillnet fishery for salmon in the Bering Sea and\nseasonally, while others may be year-round resi-\naround the Aleutian Islands. An estimated 10,000\ndents. The migratory movements of killer whales\nDall porpoises are killed annually in that fishery\ninto and out of the Navarin Basin are not known.\n(Leatherwood and Reeves 1978).","96\nNavarin Basin Synthesis\nTwo species of beaked whale occur in the Bering\nThe abundance estimates presented must be\nSea (and likely the Navarin Basin): the Bering Sea\nconsidered provisional, given the constraints\nbeaked whale (Mesoplodon stejnegeri) and Baird's\nimposed by the limited amount of survey effort and\nbeaked whale (Berardius bairdii). Both are deep\nlow numbers of sightings on their confidence\ndivers, eat primarily squid, and are seldom seen\nlimits. However, they indicate that fin and killer\ndue to their inconspicuous surfacing behavior and\nwhales are relatively abundant residents of the\nblow. There are no estimates of their population\nNavarin Basin on a year-round basis. Further, gray\nsizes.\nwhales are likely to be common during autumn\nand bowhead and belukha whales in winter. Dur-\n8.1.3 Cetacean Prey and Abundance\ning the open-water season, the highest cetacean\nPelagic and semidemersal fishes are the most\ndensities occurred over the continental shelf-in\nwidely utilized prey of cetaceans in the Bering Sea\neffect over the outer continental shelf given the\n(Table 8.1; Frost and Lowry 1981). Euphausiids are\nsurvey area boundaries. Winter sighting effort\na major prey of all baleen whales except gray\noccurred almost exclusively in the MIZ and almost\nwhales, which are dependent upon benthic amphi-\nall cetaceans sighted were in that stratum. Nothing\npods. Squids are important in the diet of Dall\ncan be said about the densities of cetaceans in the\nporpoises and, in conjunction with deepwater\nother habitats during that period, other than they\nfishes, are a major component of sperm whale and\nprobably were lower based on observations by\nbeaked whale diets.\nother investigators.\nEstimates of the seasonal abundances of some\nBrueggeman (1983), realizing the limitations of\ncetacean species in the Navarin Basin are now\nthe available data and the difficulty in comparing\navailable as a result of four surveys in 1982-83\nresults obtained by differing methodologies,\n(Table 8.2; Brueggeman 1983). During the spring,\nspeculated that densities of fin and minke whales\nsummer, and fall surveys the basin was stratified\nat the sea surface in the Navarin Basin were lower\ninto deep water, continental slope, and continen-\nthan those reported in the north Atlantic Ocean\ntal shelf habitats. In winter, open water, marginal\nbut were above that for right whales. The fin whale\nice zone (MIZ), and interior pack ice strata were\nestimates were comparable to those from the Gulf\nused as a basis for allocation of sampling effort.\nof Alaska and much higher than North Pacific\nTABLE 8.1 -Relative importance of prey types in the diets of cetaceans in the eastern Bering Sea.\nPelagic\nNekto-\nand Semi-\nDeep-\nCephal-\nbenthonic Epifaunal\ndemersal\nDemersal\nwater\nopods and\nEuph-\nCrus-\nInver-\nMarine\nFishes\nFishes\nFishes\nSquids\nCopepods\nausiids\ntaceans\ntebrates\nMammals\nBaleen whales\nFin\nMajor\nMinor\nMajor\nMajor\nHumpback\nMajor\nMinor\nMinor\nMinor\nMajor\nMinor\nMinke\nMajor\nMinor\nMinor\nMajor\nBowhead\nMajor\nMajor\nMinor\nGray\nMinor\nMajor\nMajor\nToothed whales\nSperm\nMinor\nMinor\nMajor\nMajor\nMinor\nKiller\nMajor\nMinor\nMinor\nMajor\nBeaked\nMinor\nMajor/\nMajor\nMinor\nminor\nBelukha\nMajor\nMinor\nMinor\nMinor\nDall porpoise\nMinor\nMinor\nMajor\nMinor\nMinor\nSOURCE: Frost and Lowry 1981.","Marine Mammals\n97\n173°\n172°30'\nElephant Rock\nNorth Cove\nHALL ISLAND\nSteller sea lion\nArre Rocks\nSpotted seal\nGlory of Russia Cape\nWalrus\n60\n30'\n60°30'\nLunda Point\nSplit Rock\nSugarloaf Mtn.\nST. MATTHEW ISLAND\nCape\nUpright\n10\n0\n10\n20\n30 km\n60°\n15\n60°15'\n6\n0\n6\n12\n18 mi\nPINNACLE ISLAND\n173°\n172°30'\nFIGURE 8.3-Marine mammal haulouts, St. Matthew Island area. Symbols indicate appproximate locations. (Data\nsource: Frost et al. 1983.)\nestimates. Generally speaking, densities of ceta-\nculties involved in obtaining data from offshore\nceans in the Navarin Basin during the open-water\nwaters. The available data on pelagic distributions\nseason appeared lower than elsewhere except for\nof pinnipeds in the Navarin Basin planning unit\nfin and right whales, which were similar or higher.\nduring the ice-free season consist in the main of\nrelatively few opportunistic sightings obtained over\n8.2 PINNIPEDS\nmany years and thus are unsuited for calculation\nof abundance estimates; the following discussions\nFour hair seals, the walrus, and two eared seals\ntherefore emphasize species' occurrence, ecology,\ninhabit the Navarin Basin seasonally. The bulk of\nand trophics. Pinniped usage of haulouts on St.\nthe available information on ice-associated pinni-\nMatthew and adjacent islands is known from\npeds comes from coastal areas of the Bering Sea,\nseveral surveys of the islands. Haulout locations\nlargely as a consequence of the logistical diffi-\nare shown in Figure 8.3.","Navarin Basin Synthesis\n98\nsemidemersal fishes compose most of their diet.\n8.2.1 Hair Seals\nThis seal is not a deep diver. In the Navarin Basin,\npollock likely predominate the diet. although\nSome 200,000 to 250,000 spotted or larga seals\neelpout are also eaten (Lowry and Frost 1981).\n(Phoca largha) inhabit the Bering Sea (Lowry and\nArctic cod, saffron cod, and capelin are major prey\nFrost 1981). There are few published sightings of\nspecies to the north. Virtually all of the feeding\nthis species within the Navarin Basin but this\ndata are from the spring season. About 6,000 spot-\nspecies is certainly present in the marginal ice\nted seals are harvested annually for subsistence\nzone, which typically consists of small ice floes up\nuse by Alaskan natives.\nto 9 m wide in slush ice, from late fall through mid-\nBetween 1 and 1.5 million ringed seals (Phoca\nApril. During two aerial surveys west of St. Mat-\nhispida) inhabit the Bering and Chukchi seas\nthew Island in April 1977 spotted seals constituted\n(Lowry and Frost 1981). They are circumpolar in\n74% and 94% of the seals seen (Burns and Harbo\ndistribution and are only found in the Bering Sea\n1977; Burns et al. 1981a). The species was also\nduring the seasonal occurrence of sea ice (Novem-\nrelatively abundant in April 1978 and 1979 in the\nber to June). The ringed seal probably dives to no\nregion between St. Matthew and St. Lawrence\nmore than 200 m. In winter, the population is\nislands, where it comprised 19-75% of all seals\nfound primarily in coastal areas over the continen-\nsighted. Spotted seal densities in the two regions\ntal shelf, but also lives in deep water areas in heavy\nranged from 0.09 to 0.34/km², as compared to\npack ice where it likely forages in the upper water\n0.07 to 1.97/km² in outer Bristol Bay during the\ncolumn. Ringed seals are the only seals that main-\nsame month (see Burns et al. 1981a).\ntain breathing holes in the thick stable fast ice.\nFemales give birth on the ice in late March and\nRinged seals excavate lairs in accumulated snow,\nApril and young use the shelter of ice hummocks\nwhich are used for resting and giving birth to pups\nand crevices (Burns 1978). After April subadults\n(Burns 1978). Recent sightings of this species in\nmove to coastal waters. In summer spotted seals\nthe Navarin Basin are distributed in the north-\nuse a number of haulouts on St. Matthew and\neastern portion of the planning unit (Fig. 8.4).\nneighboring islands. Frost et al. (1983) have\nBurns (1978) reported 2.4 to 3.1 individuals/km2\ntabulated data indicating several hundred animals\nin limited areas of landfast ice in the Chukchi Sea.\nmay be present at the haulouts at a given time.\nLowry and Frost (1981) have summarized the\nFeeding habits of spotted seals vary with loca-\nfeeding habits of ringed seals. Along the north-\ntion and perhaps with season but pelagic and\nTABLE 8.2-Sightings of cetaceans and estimates of their abundance in the Navarin Basin, 1982-83.\nFall*\nWintert\nSpring*\nSummer*\nNumber\nEstimated\nEstimated\nNumber\nEstimated\nNumber\nEstimated\nNumber\nObserved\nAbundance\nAbundance\nObserved\nAbundance\nObserved\nAbundance\nObserved\n225\n6\n136\nFin whale\n26\n259\n6\n84\n13\n0\n2\n57\n0\nRight whale\n0\n-\n-\n-\n44\n500\n0\nGray whale\n0\n0\n-\n-\n-\n25\n171\n0\n0\nBowhead whale\n0\n-\n-\n-\n3\n25\n1\n23\nMinke whale\n3\n15\n1\n-\n17\n798\n7\n5\n42\nKiller whale\n35\n396\n-\n0\n606\n462\nBelukha whale\n0\n0\n-\n-\n-\n56\n0\nDall porpoise\n65\n54\n-\n-\n-\n-\n647\n792\n670\n68\n183\n133\n1,548\nTotal\n129\nSOURCE: Data from Brueggeman 1983.\nNOTE: Number observed includes animals seen outside transects; estimated abundance is based only on animals in transects.\nBased on observations in shelf, slope, and deepwater habitats.\n+ Based on observations in marginal ice zone only.","Marine Mammals\n99\n175°\n175°\n180°\n170'\n50\n0\n100\n200 km\n63\n63\n50\n0\n50\n100 mi\nD\n61\n61\n59\no\n59\nRinged\n57\nFIGURE 8.4-Sightings of\nBearded\n57\nphocid seals in the Nav-\nRibbon\narin Basin and vicinity.\n(Data source: NOAA,\n175°\n180°\n175\n170°\nNMFS, unpubl.)\neastern Bering Sea coast over 80% of the seal's\nic in the Bering Sea throughout summer.\ndiet consisted of Arctic cod, saffron cod, sculpins,\nMost trophics data for ribbon seals have been\nshrimps, mysids, and amphipods, varying seasonal-\nobtained from animals collected in spring, when\nly and geographically in relative importance.\nthere is apparently little feeding taking place. Frost\nCrustaceans compose 98% of a newly weaned\nand Lowry (1980) and Lowry and Frost (1981) have\npup's diet but only 20% of an adult's diet. There\nsummarized available information. Pollock is the\nare age-related gradations between these extremes\nnumerically dominant prey in (and to the south\nand the rest of the diet is composed of fishes. Year-\nof) the Navarin Basin area between March and\nto-year variability in primary prey at a given loca-\nJune. Although eelpout are second numerically,\ntion occurs and is likely related to the differing\nthey may contribute more (by weight) to the seal's\navailability of prey. About 7,000 to 9,000 ringed\ndiet. Greenland halibut, pricklebacks, and capelin\nseals are harvested annually by Native hunters.\nare also taken there. Arctic cod is the most impor-\nRibbon seals (Phoca fasciata) inhabit primarily\ntant prey species to the northeast and invertebrates\nthe Bering and Okhotsk seas, but may venture into\nappear important to the northwest. Only two seals\nthe southern Chukchi Sea during summer. The\nhave been examined during the winter period of\n(Interagency Bering Sea population Group 1978). spotted 100,000\nis estimated at\nactive feeding: one contained only pollock and the\nTask Like the\nother had eaten only Arctic cod.\nseal, ribbon seals inhabit the marginal ice zone\nThe bearded seal (Erignathus barbatus) is cir-\nfrom late fall through spring. They haul out on the\ncumpolar in distribution and numbers approx-\nfloes to rest, pup. nurse, and molt. They do not\nimately 300,000 in the Bering and Chukchi seas\nbuild of life lairs. Pups need floes for the first 4 they weeks\n(Lowry and Frost 1981). It is broadly distributed and\nas a place to nurse and haul out as are\nmoves seasonally with the sea ice, preferring\napparently poor swimmers. Ribbon seals are pelag-\ndisturbed ice (caused by winds, currents, and","Navarin Basin Synthesis\n100\n175°\n175°\n180\n170\n50\n0\n100\n200 km\n63°\n63\n50\n0\n50\n100 mi\n61°\n61\n59\n59\nFIGURE 8.5-Sightings of\n57\nSteller sea lions and\nWalrus\n57°\nSea lion\nwalruses in the Navarin\nBasin and vicinity. (Data\nsource: NOAA, NMFS,\n175'\n180°\n175\n170°\nunpubl.)\ncoastal features), which is more abundant during\nincluding the ice front. Aerial surveys in spring\nwinter in the central and southern Bering Sea\n1976 indicated that most Bering Sea walruses were\n(Burns and Frost 1983). The distribution of recent\nin the vicinity of St. Lawrence Island (Krogman et\nal. 1978). Fay (1982) shows two major concentra-\nsightings in the Navarin Basin is similar to that for\nringed seals (Fig. 8.4). Bearded seals pup on the\ntions of walruses in the Bering Sea during late\nwinter and early spring: one in the vicinity of St.\nice in spring. In contrast to other seals, the young\ncan enter the water and swim immediately after\nLawrence Island, the other in Bristol Bay. Fewer\nbirth. The bearded seal is an important subsistence\nanimals are found in the marginal ice zone be-\nspecies; some 1,000-5,000 were harvested annual-\ntween these concentrations. The majority of the\nly in Alaska between 1966 and 1977 (Burns and\nwalruses, mainly females and immature males,\nFrost 1983). Bearded seals are benthic feeders and\nfollow the receding ice pack. Young are born\ngenerally forage in depths less than 160 m (Burns\nduring the northward migration; as with the beard-\n1978). Crabs, shrimps, and clams compose most\ned seal, newborn walruses can enter the water and\nof the bearded seal's diet, but the relative impor-\nswim immediately. Some walruses, mostly bulls,\nspend the summer in Bristol Bay, the Pribilofs, and\ntance of each often varies geographically or year\nthe northern Bering Sea. Over 12,000 walruses\nto year (Lowry et al. 1980).\nwere observed near the northwest tip of St. Mat-\n8.2.2 Walruses\nthew Island in April 1975. There are a number of\nKrogman et al. (1978) estimated about 210,000\nrecords of walruses hauling out in the St. Matthew\nwalruses inhabited the Chukchi and Bering seas\nIsland area; they are summarized in Frost et al.\nas of 1975. The population is now believed to be\n(1983). Recent walrus sightings in the Navarin Basin\napproaching pre-exploitation levels and attaining\noccurred most frequently in the northeastern por-\nthe carrying capacity of the environment. During\ntion of the planning unit (Fig. 8.5).\nwinter and spring, walruses inhabit moving ice,\nPacific walruses are benthic feeders and largely","Marine Mammals\n101\nportion of the Navarin Basin is near the northern\nrestricted to the continental shelf where water\nlimit of the range of this species.\ndepths are less than 80-100 m (Fay 1982). Fay\nBraham et al. (1980) have documented a decline\n(1982) has summarized feeding habits research\nin sea lion numbers in the eastern Aleutian Islands\nconducted by a number of investigators in the\nand suggest this may be due to reduced prey avail-\nBering Sea. Walrus are highly selective feeders.\nability (especially pollock) as a result of rapidly\nBivalve molluscs compose by far the bulk of the\ndeveloping commercial fisheries in the Bering Sea.\nidentifiable food at most locations.\nSea lions feed primarily on pelagic and semidemer-\nAbout 80% of the annual harvest of walruses in\nsal fishes and to a lesser extent on invertebrates\nAlaska is taken in May and June in the St. Law-\nand demersal fishes (Calkins and Pitcher 1983).\nrence Island-Bering Strait region (Fay 1982). The\nAn estimated 1.7 million northern fur seals\ntotal retrieved harvest by American Eskimo hunt-\n(Callorhinus ursinus) inhabit the North Pacific and\ners has been 1,000-3,000 animals annually since\nBering Sea; 1.25 million breed or haul out on the\n1965 (Fay 1982).\nPribilof Islands (U.S. Department of Commerce\n8.2.3 Eared Seals\n1980). Approximately 250,000 pups are born each\nyear, with a peak in early July. After giving birth,\nSteller (or northern) sea lions (Eumetopias\nthe females go to sea to feed between nursing their\njubatus) inhabit waters from the Pribilof Islands,\npups. They usually forage within 160 km of the\nsouth along both coasts of the North Pacific Ocean\nPribilof Islands, but occasionally out to 430 km.\nto California's Channel Islands in the east and near-\nIt appears that few fur seals range northward into\nly to Japan in the west. There are approximately\nthe Navarin Basin. Pelagic harvest records indicate\n250,000 Steller sea lions, mostly concentrated in\nno significant numbers farther than 200 km north\nthe Aleutian Islands and Alaska Peninsula areas\nof St. Paul Island in the Pribiloos, although fur seals\n(Interagency Task Group 1978). The haulout area\nhave been seen as close as 13 km to St. Matthew\nnearest to the Navarin Basin is the St. Matthew\nIsland (Harry and Hartley 1981). Following the\nIsland complex. Most recent sightings have been\nbreeding season, fur seals disperse and remain\nover the continental shelf (Fig. 8.5). Burns et al.\npelagic until the next pupping and breeding\n(1981b) state that Steller sea lions are restricted to\nseason. By December almost all fur seals are south\nthe marginal ice zone or open water adjacent to\nof the Aleutian Islands. Some, primarily females\nit during periods when ice cover extends south-\nand pups, migrate offshore as far south as southern\nward over the continental shelf. The northern\nTABLE 8.3-Relative importance of prey types in the diets of pinnipeds in the eastern Bering Sea.\nEpifaunal\nInfaunal\nPelagic\nPelagic and\nBenthic\nNektobenthonic\nBenthic\nSemidemersal\nDemersal\nNektonic\nInvertebrates\nInvertebrates\nInvertebrates\nFishes\nFishes\nInvertebrates\nHair seals\nMinor\nHarbor seal\nMajor\nMinor\nMinor for adults\nSpotted seal\nMajor\nMajor\nMinor\nfor juveniles\nMajor for juveniles\nMinor\nRibbon seal\nMajor\nMajor\nRinged seal\nMajor\nMajor\nMajor\nMinor\nMajor\nMajor in\nMajor\nBearded seal\nMinor\nsome areas\nMajor\nMinor\nMinor\nWalrus\nEared seals\nFur seal\nMajor (squids)\nMajor\nSea lion\nMinor\nMajor\nMinor\nSOURCE: Lowry and Frost 1981","102\nNavarin Basin Synthesis\nof the fur seal population may die annually due\nCalifornia by January.\nto the direct effects of fisheries (Fowler 1982).\nFur seals dive to at least 180 m. In the Bering\nSea they eat pollock, capelin, sand lance, herring,\n8.2.4 Pinniped Prey and Abundance\nseveral species of squid, and Atka mackerel (Fiscus\nIt is apparent that pelagic and semidemersal\n1978). Near the Pribilof Islands squid would be\nfishes are major food sources for all pinnipeds in\nranked the most important food by frequency of\nthe Bering Sea but the bearded seal and walrus,\noccurrence, but pollock accounts for 67% of the\nwhich rely heavily upon benthic invertebrates\nfood eaten by volume and other gadids account\n(Table 8.3; Lowry and Frost 1981).\nfor an additional 15%. The great use of pollock\nSighting data are in general too sparse to deter-\nby fur seals and the development of a large pollock\nmine seasonal densities of pinnipeds in the Navarin\nharvest by man over the last 15 years has been\nBasin planning unit. The winter period is an excep-\ncited as a possible cause for an apparent reduc-\ntion. Brueggeman and Grotefendt (1984) estimated\ntion in fur seal carrying capacity (U.S. Department\ndensities of five species in the marginal ice zone\nof Commerce 1980). More recently, prey availabili-\nduring February-March 1983, as follows (in indi-\nty has been shown to be sufficient to support the\nviduals per square kilometer): walrus (0.587),\nfur seal population and evidence has been present-\nnorthern sea lion (0.012), spotted seal (0.046),\ned that entanglement of the seals in gillnets causes\nribbon seal (0.006), and bearded seal (0.001).\nmortalities, preventing a return to the population\nlevel prior to about 1956. Five percent or more","Chapter 9.\nOil and Gas Development\nand Related Issues\nLAURIE E. JARVELA, LYMAN K. THORSTEINSON AND MAURI J. PELTO\nU.S. Department of Commerce, NOAA, National Ocean Service, Office of Oceanography and Marine Services,\nOcean Assessments Division, Alaska Office, Juneau, Alaska\nIf commercial quantities of petroleum or natural\nconcerns about possible consequences of OCS\ngas are discovered in the Navarin Basin, a series\nactivities are identified, (2) requests for resource\nof events likely to affect not only the Navarin Basin\nreports from interested organizations and individ-\nper se, but also other parts of Alaska, will be\nuals, (3) directed environmental and socioeconomic\ninitiated. Oil and gas development in the region\nstudies, and, finally, (4) synthesis meetings. Past\nwill require infrastructure to support exploration\nOCSEAP synthesis meetings considered environ-\nand production activities. Logistical support bases\nmental impacts on regional biota and ecosystems.\nwill be required, as will oil storage and loading\nThe Navarin Basin meeting was a milestone of\nfacilities. Aircraft and ship traffic will increase.\nsorts in that it formally included a socioeconomic\nThese developments imply effects on regional eco-\ncomponent.\nsystems and social, economic, and cultural systems,\nFour major issues were analyzed at the Navarin\nsome of which will be geographically far removed\nBasin synthesis meeting: environmental hazards\nfrom the site of the discovery.\nto development, and impacts on fisheries, seabirds,\nAssessments of the potential impacts of OCS oil\nand marine mammals. These issues are, of course,\nand gas development are an integral part of the\ncomposed of a number of sub-issues, which are\ndecision process preceding federal OCS lease sales.\ndetailed herein. Presentation of the results of the\nThe assessments are major elements of environ-\nanalyses is preceded by discussions of resource pro-\nmental impact statements and other documents\njections, exploration and production scenarios, and\ngenerated by the Minerals Management Service.\noil spill scenarios that were used as a framework\nAssessment proceeds in several ways. A corner-\nfor the analyses.\nstone of the process is the petroleum technology\nassessment, which specifies feasible field develop-\n9.1 RESOURCE PROJECTIONS AND\nment strategies based upon assumptions about\nEXPLORATION, DEVELOPMENT,\nrecoverable reserves, environmental constraints.\nAND PRODUCTION ASSUMPTIONS\napplicable technology, manpower requirements,\n9.1.1 Resource Projections\nreservoir characteristics, and economics. MMS's\npetroleum technology assessments usually are\nThe Navarin Basin province includes three major\ndeveloped for three levels of activity-a small find,\nsedimentary basins and significant thickness of\na mean case, and a bonanza find-in order to\ndeposits, suggesting possible hydrocarbon accumu-\nbound the subsequent impact assessments.\nlations. The available geological information\nImpact assessment couples petroleum technol-\nindicates a definite potential for giant discoveries\nogy assessment with pertinent environmental and\n(Wilson et al. 1982). Several large anticlinal struc-\nsocioeconomic issues. The latter are generated\ntures are present. as are numerous smaller folds,\nthrough various mechanisms, such as (1) \"scoping\"\ndiapirs, and stratigraphic traps. The great thickness\nmeetings, during which regional and community\nof sediments suggests that reservoirs could occur\n103","Navarin Basin Synthesis\n104\nply and crew change transportation. Crew changes\nat several depths. Prospective reservoirs probably\ncould occur via large helicopters operating out of\nlie at depths ranging from 1,500 to 7,500 m (Wilson\nNome. Resupply of drilling muds, water, and other\net al. 1982). A Continental Offshore Stratigraphic\nbulky materials would likely be by vessels from\nTest (COST) well drilled in the summer of 1983 will\nDutch Harbor/Unalaska in the western Alaska\nprovide the first stratigraphic information.\nPeninsula area. Industry drilling of a COST well\nEstimates of potential mean recoverable re-\nin the Navarin Basin employed a semisubmersible\nsources in the Navarin Basin have recently been\ndrilling rig. Logistical support was as noted above.\nrevised, apparently the consequence of better\nThe use of St. Matthew Island as a forward sup-\ngeological information becoming available.\nport base is desired by industry and appears likely\nThe 1981 USGS mean estimates of recoverable\nas a consequence of a land swap between the U.S.\noil and gas in the basin were 1.74 billion bbl and\nFish and Wildlife Service and Native corporations.\n5.426 trillion ft respectively (Wilson et al. 1982).\nDrilling of medium to deep exploratory wells\nThe mean estimates presented by MMS at the\ncan be expected to take 3 to 5 months per well\nNavarin Basin synthesis meeting and used for\n(Wilson et al. 1982). Each exploration rig likely\nimpact analyses are 1.2 billion bbl of oil and 7.08\nwill be attended by two supply and anchor vessels\ntrillion ft3 of non-associated gas (F. Sieber pers.\nand two helicopters. Because of the great supply\ncommun.). Those mean estimates are bounded by\nline distances, larger vessels than might otherwise\nlow and high estimates of 0.6 billion bbl of oil and\nbe needed to operate in the anticipated weather\n3.54 trillion ft3 of gas and 2.4 billion bbl of oil and\nconditions may be used (Wilson et al. 1982). The\n14.6 trillion ft3 of gas, respectively. Development\nexploratory season might be lengthened by using\nand production scenarios were developed by MMS\nice-reinforced drillships or platforms supported by\nfor each of the three resource levels. Although\neconomic analyses suggest that gas development\nice breakers.\ncurrently is not economically feasible, it was con-\nMean Case Production\nsidered in the scenarios.\nFor the purpose of the mean case production\n9.1.2 Exploration and Production Scenarios\nscenario, the development period was to begin in\n1991. A total of 227 production and service wells\nOf the many approaches that can be taken to\ncould be drilled between 1993 and 2000. Perhaps\nOCS oil and gas development in the Navarin Basin,\n13 platforms would be installed. Oil production is\nall must consider severe weather conditions, sea-\nexpected to begin in 1994. This forecast is quite\nsonal presence of sea ice, and the remoteness of\noptimistic and oil may not be produced for at least\nthe area from suitable onshore sites for support\n12 or 13 years following the sale (H. Jahns pers.\nand terminal facilities. Other factors influencing\ncommun.). Peak production would occur between\nactivities include water depths (typically 120-140\n1999 and 2005 with 96 million bbl being produced\nm over the sedimentary basins), site conditions,\nannually (263,000 bbl/d). Oil production would\nfield size, reservoir and production characteristics,\nend between 2011 and 2013.\nquality and physical properties of the oil and gas,\nIn deep-water areas such as the Navarin Basin,\nand, finally, economics. The following scenarios\neconomic constraints favor oil fields with as few\nwere presented by MMS (F. Sieber pers. commun.)\nplatforms as possible and integrated drilling and\nas possible approaches based on the three resource\nproduction units, as has been the trend in the\nestimates given above.\nNorth Sea (Wilson et al. 1982). Perhaps 32 to 48\nExploration\nwells would be directionally drilled from each plat-\nform. In a separate scenario based on a find of\nExploration in the Navarin Basin should begin\n1 billion bbl, Wilson et al. (1982) estimated that\nin 1986 and end in 1992. Activity is expected to\nthree production platforms would be required for\npeak in 1988 and 1989, with nine wells drilled each\na total throughput of 300,000 bbl of oil per day\nyear. Large drillships or ice-strengthened semisub-\n(assuming that each platform would have 40 pro-\nmersibles will be required for exploration, which\nducing wells). Steel jacket or concrete gravity\nwill probably be confined to the open-water sea-\nproduction structures are likely to be employed\nson, roughly from May to November. Logistical\nin the Navarin Basin. In order to resist ice forces,\nsupport will require long-distance air or sea sup-","Oil & Gas Development & Issues\n105\nthey would likely be somewhat modified versions\nstabilization, and LPG recovery. A decision to\nof platforms currently in use elsewhere.\ndevelop gas resources would require construction\nThe principal design criteria for a Navarin Basin\nof facilities for liquefaction, storage, and loading\nproduction structure are as follows (Wilson et al.\ninto ice-reinforced LNG tankers. The Cape Upright\n1982):\nFlats at the southeastern end of St. Matthew Island\n1) wave loading;\nis the most attractive area for siting such facilities\n2) ice loading;\n(Wilson et al. 1982).\n3) competent seafloor soils (for gravity struc-\nConstruction of an oil terminal on St. Matthew\nture);\nIsland would take about 24 months and require\n4) oil storage capacity (if appropriate);\nan average of about 550 workers on site. About\n5) installation and fabrication capabilities;\n100 year-round employees would be required to\n6) number of conductors and spacing;\noperate the facility.\n7) crude oil transportation means (pipeline or\nIce-breaking shuttle tankers, similar to the\ntanker);\nManhattan, would be used to transport crude oil\n8) seismic loading; and\nfrom St. Matthew Island to Morzhovoi Bay. These\n9) topside facilities.\nvessels would probably be about 150,000 dwt (1\nGravity production platforms may be favored\nmillion bbl) (Wilson et al. 1982). Assuming 30 hours\nbecause of their inherent storage capacity and the\nto load a tanker and an equivalent time to unload,\nfaster installation possible. Because more of the\nplus 62 hours to make a round trip to the facility\nconstruction of gravity structures can be accom-\nsome 800 km away in the Alaska Peninsula region,\nplished at an onshore facility, this is a positive\nplus downtime, two 150,000-dwt tankers would be\nfactor in view of the Navarin Basin's remote loca-\nrequired. The tankers would unload into storage\ntion, limited construction season, and brief good\ntanks at the transshipment port and the crude\nweather \"windows.\"\nwould subsequently be loaded into VLCC tankers\nHelicopter and vessel support requirements for\nfor transport to West Coast or other refineries.\nproduction platforms would consist of about one\nMarine support to the Navarin Basin would prob-\nof each during the production phase. It is assumed\nably be out of Dutch Harbor/Unalaska. Cold Bay\nthat a vessel would be committed to each platform\ncould serve as the primary air support site.\nat all times and that it would have oil spill con-\nLow Case Production\ntainment and firefighting capabilities.\nThe mean case scenario assumed that oil and\nFor the low case scenario, it was assumed that\ngas would be piped 240 km to St. Matthew Island\n600 million bbl of recoverable oil and no natural\nfor subsequent transfer to a transshipment term-\ngas would be extracted. The exploratory period\ninal in the Morzhovoi Bay area on the south side\nwould begin in 1986 and end in 1991. By 1995 six\nof the Alaska Peninsula. Pipeline construction\nplatforms would be in place. Development drilling\ncould begin in 1992 and end in 1993. An 18-in\nwould begin in 1993 and end in 1998; a total of\n(46-cm) oil line and 36-in (92-cm) gas line would\n114 wells would be drilled. Peak annual produc-\nbe laid. For laying large-diameter pipe, a third\ntion of 57 million bbl of oil (156,000 bbl/d) would\ngeneration semisubmersible lay barge might be\noccur between 1998 and 2003. Oil production\nused due to its capability to work in waves up to\nwould cease sometime between 2008 and 2010.\n4.5 m high (Lochridge 1980).\nThe low case scenario assumes offshore loading\nAs noted above, St. Matthew Island was con-\nof crude oil would occur. Consequently, gravity\nsidered a viable site for the location of forward sup-\nplatforms having internal storage are attractive for\nport and transshipment facilities in the scenarios\nthis scenario. Concrete gravity platforms having\npresented at the synthesis meeting. Land-based\nboth production and storage capabilities, such as\nfacilities there would include an airport, a base for\nthose now in use in the North Sea, might be adap-\nworkboats, storage tanks for holding oil and gas,\nted for the Navarin Basin. Some of these provide\nand loading facilities. The terminal would have a\na million barrels of oil storage (Coleman 1980). As\nstorage capacity for about 10-15 days of crude oil\nin the mean case scenario, ice-strengthened shuttle\nproduction (2.5-4 million bbl), as well as\ntankers would transfer the crude oil from the off-\ncapabilities for tanker ballast treatment, crude oil\nshore facilities to the remote VLCC transshipment","106\nNavarin Basin Synthesis\nof 433,000 bbl/d. Dutch Harbor/Unalaska and Cold\nterminal in the southern Alaska Peninsula area.\nBay would serve as the main marine and air sup-\nAn ice-breaking workboat would be needed at\neach offshore loading platform to serve normal\nport bases.\nworkboat functions as well as to assist during dock-\n9.2 OIL SPILL TRANSPORT, ENVIRON-\ning maneuvers. Data presented by Wilson et al.\nMENTAL PARTITIONING, AND FATE\n(1982) suggest that a single 150,000-dwt shuttle\ntanker or perhaps two smaller tankers would be\nThe impacts of petroleum on biota and habitats\nsufficient to handle the peak throughput of oil used\nare inextricably linked to the transport, partition-\nas a basis of the offshore loading scenario.\ning, and transformation processes acting on the\nIt is expected that in the Navarin Basin sea ice,\noil between points of release and contact. These\nfog, and structural icing would limit or shut down\nprocesses include advection, spreading, evapora-\noffshore loading operations at frequent intervals\ntion, dissolution, emulsification, dispersion, auto-\nduring winter. The offshore storage facility would\noxidation, biodegradation, and sedimentation\nhave to be capable of holding perhaps 10 days'\n(Figs. 9.1 and 9.2). It is crucial for impact assess-\nthroughput of oil to allow for such downtime. Cur-\nment to understand these processes in order to\nrently used offshore loading systems are not\naccurately predict the outcomes of spill events. In\ndesigned to operate in sea ice, so the low find\nrecent years great strides have been made in our\nscenario would require development of new\nknowledge of the partitioning and fate of spilled\ntechnology (Wilson et al. 1982).\noil in a variety of environmental settings and cir-\nMaximum Case Production\ncumstances through observations of actual oil\nspills, laboratory investigations, and theoretical\nIn the maximum case scenario, the exploratory\nstudies. The development of more sophisticated\nperiod would begin in 1986 and end in 1992. De-\noil spill simulation models has facilitated the predic-\nvelopment would begin in 1991, with 18 platforms\ntion of spilled oil transport and fate. Existing\nin place by 1996. Development drilling would start\nmodels are capable of portraying the vertical as\nin 1993 and a total of 454 wells is projected. It was\nwell as horizontal movements of oil in the sea, oil\nassumed that oil and gas would be transported\nmovements in ice-infested waters, and the fate of\nthrough 480-km-long pipelines to St. Paul Island\noil (Huang 1983; Liu and Leendertse 1981). The\nin the Pribilofs; 24-in (60.0-cm) diameter pipe\nfollowing paragraphs present oil spill simulations\nwould be employed for crude oil, and 42-in (107-\ndeveloped for the Navarin Basin region, and ex-\ncm) pipe for gas. Three booster platforms probably\namine the potential environmental partitioning\nwould be required along the pipelines. Peak crude\noil production would occur between 2000 and\nand fate of petroleum.\n2007, when it would attain 158 million bbl annually\n9.2.1 Advection\n(433,000 bbl/d). Oil production would cease be-\ntween 2014 and 2016. Gas production would begin\nOil spill trajectories in the Navarin Basin were\nconcurrently with oil production, and would peak\ncalculated by means of a model that predicts the\nbetween 2002 and 2007 with 929 billion ft3 (26\nadvection of oil in the presence of either ice cover\nor open water (Liu and Leendertse 1981). The oil\nbillion m³) produced each year.\nSt. Paul Island, instead of St. Matthew, is envis-\nspill model employs functions derived from a circu-\nlation model (see Section 4.4) that define the\naged as the forward support base for operations\nin this scenario. Because the present air and\nresponse of each of 10 water layers to unit wind\nstress. Using these response functions, the motion\nmarine facilities on St. Paul would not support such\nimparted to water, oil, or ice by winds can be\nactivities, major construction would have to occur\non the island. Again, ice-strengthened shuttle\ndetermined. The summation of a sequence of mo-\ntankers would transport produced petroleum from\ntions is the trajectory. Winds are derived from a\nthe St. Paul marine terminal to the remote VLCC\nstochastic wind model which incorporates the\nterminal in Morzhovoi Bay. About 97 hours would\neffects of low-pressure atmospheric cells and their\nbe required for a round trip, including the loading\nprogressive motions (see Fig. 3.7). The wind model\naccounts for latitudinal variations of the Coriolis\nand unloading operations. Two 150,000-dwt shuttle\neffect and temperature. It is uniform longitudinally\ntankers would be necessary to handle a throughput","Oil & Gas Development & Issues\n107\nPhotochemical reactions\nAdsorption\nOxidation\nPrecipitation\nRemoval,\nCO2\nclean-up\nDry fallout\noperations\nAerosol\nOIL\nformation\nOILY WATER DISCHARGE\nWeathering\nEvaporation\nBeach tar\nstranded tar\nOil slick\nstranded\noxidation\nMousse\nPatches\nTar balls\nSpreading\nAdsorption\nSolution\nFlakes\nBeach\nConvection\npenetration\nDispersion\nMicro\nmigration\nparticulate\nrelease\nEmulsion\ntar\nChemical\nDispersed\ndegradation\naccommodated\nCO2\nBiodegradation\nSolution\nIn suspension\n?\nIngested\nfood web depurated\nUpwelling\nSedimenting\nFecal pellets\nresidues\nDetritus\nSedimenting\nOIL\nparticulate\nresidues\nSubsurface\nResuspension\nspill\npore water release\nRedistribution: dredging, storms\nBenthos: reworking, turnover, biodegradation\nSedimentation\niburiali\nFIGURE 9.1-General - pathways and mechanisms of the fate of oil. (Redrawn from Clark 1982.)\nexcept when the stochastic process calls for a cir-\ntation of petroleum products may take place in\ncular pattern due to passage of a cyclonic feature\nthe Bering Sea, including selected Navarin Basin\n(Liu In prep.).\nsites. The trajectories are representative of all\nFigures 9.3-9.5 show sample trajectories of\nprobable events, based on a 20-year history of\n30-day duration from sites representative of loca-\nwinds; they were calculated for three periods. (See\ntions where either OCS development or transpor-\nFig. 3.5.) July-August is defined roughly as that","Navarin Basin Synthesis\n108\nTime, hours\nyear 104\n100 week\nmonth 103\n10\nday\n0\n1\nSpreading\nDrift\nC9\n(aromatics)\nC8\nC7\nC6\nEvaporation\nC14\nC15 (n-alkanes)\nC13\nC11\nC12\nDissolution\nhorizontal\nvertical\nDispersion\nEmulsification\nSedimentation\nBiodegradation\nPhotooxidation\nFIGURE 9.2-Relative magnitudes and timescales of the redistributive processes for the fate of oil spilled at sea.\nThe development of processes as time elapses after a spill: line length indicates the probable timespan of a process;\nline width shows the changes in the magnitude of a process with time and compares it with other contemporary\nprocesses. (Redrawn from Clark 1982.)\nduced more scatter in the particle trajectories,\nperiod when winds are dominantly from the south.\npresumably because of the transitional nature of\nSeptember-December is a transition period when\nthe weather patterns during that period of the\nwinds progressively increase and become more\nyear. Ensemble envelopes described arcs of about\nnortherly in origin. January-June is a period when\n80° and 90° in the northern and southern parts,\nice cover is a probable event.\nrespectively, of the planning unit. Both envelopes\nDuring July-August the prevalent direction of\nwere oriented toward the southwest. Based on the\nmotion at the sea surface was northeastward. The\nindividual net displacements of particles, mean\nensemble of individual particle trajectories com-\nspeeds of about 7 cm/s appear to be typical,\nposes an envelope describing an arc of about 30°.\nalthough speeds of 10 cm/s were attained.\nThe mean rate of movement of a particle during\nThe scatter of individual particle trajectories in\nthe simulation was about 10 cm/s based on a net\nthe January-June simulations was intermediate\ndisplacement of about 225 km during the 30-day\nbetween the other two, being approximately 45°\nsimulation.\nabout the origin. The direction of movement was\nThe simulations for September-December pro-","Oil & Gas Development & Issues\n109\n180°\n170°\n160°\nU.S.S.R.\nKotzebue Sound\nKolyuchin Bay\nEast Cape\nZaliv Kresta\nPrince\nSEWARD\nof Wales\nPENINSULA\nmy\n65°\n65\nO\nNome\nSt. Lawrence 1.\nCape Navarin\nNorton Sound\nBristol Bay\n60\nO\n60\nSt. Matthew I.\nNunivak I.\nBAY\nSt. Paul I.\nSt. George 1.\n55°\n55\nUnimak Pass\nLaunch Points\n7 13 20 22 26\nA\n180°\n170°\n160 O\nFIGURE 9.3-Oil spill trajectory simulations, July-August. (Adapted from Liu 1981.)\nwesterly. Maximum net movements of individual\nNote in Figure 9.5 that the trajectories differ\nparticles for the duration of the simulation were\ngreatly between nearby areas for equivalent\nabout 280 km. which is indicative of 12 cm/s mean\nwinds. The effect of shallow water is to increase\nparticle speeds; however, speeds of 9 cm/s appear\nthe turbulent energy density and to retard the\nmore typical.\nmotion of oil or ice at the sea surface. In nearshore","Navarin Busin Synthesis\n110\n160°\n170°\n180°\nU.S.S.R.\nKotzebue Sound\nKolyuchin Bay\nEast Cape\nZaliv Kresta\nPrince\nSEWARD\nof Wales\nPENINSULA\n65°\n65\nNome\nNorton Sound\nCape Navarin\nSt. Lawrence\nSt. Matthew 1.\nBristol Bay\n60\no\n60°\nNunivak I.\nBAY\nSt. Paul I.\nSt. George I.\n55°\n55\nUnimak Pass\nLaunch Points\n4 12 13 14 16 19 26\nJAN\n160°\n180°\n170°\nFIGURE 9.4-Oil spill trajectory simulations, September-December. (Adapted from Liu 1981.)\nareas the response of the water column is general-\nin the environment is an important consideration\nly parallel to shore, and as a result the trajectories\nin determining the ultimate fate and effect of\npetroleum hydrocarbons. Thus considerable effort\ntend to follow the coastline.\nwas directed toward the development of quanti-\n9.2.2 Horizontal and Vertical Spreading\ntative estimates for use during the Navarin Basin\nThe three-dimensional spreading of spilled oil\nSynthesis Meeting. These estimates were based on","Oil & Gas Development & Issues\n111\n180\n170°\n160\nU.S.S.R.\nKotzebue Sound\nKolyuchin Bay\nEast Cape\nZaliv Kresta\nPrince\nSEWARD\nof Wales\nPENINSULA\n65\nO\n65°\nNome\nCape Navarin\nNorton Sound\nSt. Lawrence 1.\n60\n60\nSt. Matthew I.\nBristol Bay\nNunivak I.\nBAY\nSt. Paul 1.\nSt. George I.\n55°\n55'\nUnimak Pass\nLaunch Points\nD\n7 14 16 20 26\n180°\n170°\n160\nFIGURE 9.5-Oil spill trajectory simulations, January-June. (Adapted from Liu 1981.)\nrepresentative oil spill scenarios and some assump-\nsummer, so no ice would be present, and both\ntions about the environmental conditions likely to\ninvolved a total of 1.6 X 106 liters (10,000 bbl) of\naccompany the spills.\noil having a composition similar to Prudhoe Bay\nTwo oil spill scenarios were developed: one\ncrude. The wind was assumed to be constant in\ninvolving an instantaneous release, the other a\ndirection at 5.0 m/s. Air temperature was 2°C.\nprolonged release. Both spills occurred during\nUnder these assumptions, the slick would move","Navarin Basin Synthesis\n112\nWind\nEvaporation\nS\nOil in Patches\nDispersing\nOil Particles\nWind Dritt\n()\nCC\nFIGURE9.6-Schematic of\na cross-section of the\nocean with surface water\nmoving downwind. A cur-\nrent shear and turbulence\ndue to wind and tides\nresult in rapid removal of\noil from the area under\neach patch of oil.\nconcentrations shown in Figure 9.7 are from solu-\nat approximately 15 cm/s or 13 km/d. (A constant\ntions to a one-dimensional form of the diffusion\nwind was assumed in order to simplify calculations\nequation (Carslaw and Jaeger 1959), using disper-\nof oil concentration. A model that will accom-\nsion rates from the oil weathering model (Payne\nmodate variable winds is in preparation.)\n1982); they include both dissolved and dispersed\nAfter 1 day, the instantaneous spill of 1.6 X 106\noil fractions. Calculations of concentration are\nliters would have spread out to cover an area of\n0.65 X 106 m² (or nearly 1 km2), and would have\nbased on an experimentally determined transfer\na thickness of 0.2 cm (Payne 1982). Due to evapor-\ncoefficient which includes both molecular dissolu-\nation of volatile fractions, which include many of\ntion and dispersion. Mixing into the water column\nthe toxic compounds, the remaining oil would\nis at a rate determined by the vertical diffusivity\nconstitute 85% of the original mass. A significant\ncalculated by means of the three-dimensional\ngeneral circulation model described in Section 4.3\nportion of the oil would have been incorporated\ninto the water column (Fig. 9.6) which, were it\n(Leendertse et al. 1973; Liu and Leendertse 1979).\nIt should be emphasized that the foregoing sce-\nstationary with respect to the oil, would accumu-\nlate a concentration of dispersed oil not exceeding\nnario is a worst case due to the following assump-\n4.0 mg/liter (4 ppm) as shown in Figure 9.7. The\ntions which are idealized and unlikely to prevail","Oil & Gas Development & Issues\n113\n3.70\n24 h\n=\n= 48 h\n84 h\n=\n120 h\n2.96\n2.22\n1.48\n0.74\n0.00\n0\n20\n40\n60\n80\n100\nDepth, m\n3.70\n2h\n=\n7 h\n=\n= 14 h\n24 h\n2.96\n2.22\n1.48\nFIGURE 9.7-Dispersed oil\nprofiles, exponential fit to\ncalculated dispersion rate\n0.74\nfrom the open-ocean oil-\nweathering model. Wind,\n10 knots; vertical diffusivi-\n0.00\nty, 1.10E + 02 cm*cm/s.\n0\n20\n40\n60\n80\n100\n(Redrawn from Payne\nDepth. m\n1984.)\nin nature: (1) The oil remains in a single slick; (2)\nof the ocean affected will be a swath which is less\nthere is no relative motion between the oil and\nthan 4.8 km wide and 130 km long after 10 days,\nthe underlying water column; and (3) diffusion\nif the wind blows continuously.\noccurs only vertically. Clearly, if there is a wind,\nA different scenario of a large spill would be one\nthe slick would move relative to the underlying\nin which the oil was released over a period of time,\nwater, diffuse and disperse horizontally, very likely\nas in a blowout, and might entail spilling 3.2 X\nbreak up into slicklets, and oil concentrations\n105 liters/d (2,000 bbl/d) for 5 days. In such an\nwould be greatly diminished.\nevent, a constant wind of 5 m/s would result in\nAn instantaneous spill of 1.6 X 106 liters will have\na narrow ribbon of oil traveling downwind at 15\nan area of 1.8 X 106 m² (1.8 km2) after 10 days\ncm/s. If it stayed intact, the ribbon of oil would\n(Payne 1982). It will be broken up into slicklets such\nbe about 20 m wide within a few kilometers of the\nthat 10% of the total area is actually oiled (Stolzen-\norigin. However, as noted above, oil spills usually\nbach et al. 1977). In order to estimate effects on\nbreak up and the scattered slicks cover approx-\nbiota it can be argued that the total surface area\nimately 10% of the affected surface area.","114\nNararin Basin Synthesis\nUnder conditions such as described, the concen-\nan open-ocean, high-energy subarctic setting. Sing-\ntration of oil in the water column under the slick\nular characteristics of this spill include the high\nwould be less than 1.0 mg/liter (1 ppm) after 12\nrate of evaporation of the oil-apparently attribut-\nhours. At distances greater than 400 m from the\nable to its light weight-and the rapid formation\ncenterline of the slick, using a two-dimensional\nof water-in-oil emulsions, which might have been\ndiffusion model, concentrations would be less than\npromoted by spraying of water into the blowout\n10 ug/liter (10 ppb) (Pelto et al. 1983). Under the\nto prevent a fire. Some 35-40% of the oil evapor-\nstringent assumptions given for this scenario, the\nated before or shortly after reaching the sea sur-\nvolume of water affected by oil concentrations\nface (Grahl-Nielsen 1978). Continued evaporation\nexceeding 10 ug/liter is 1.0 km³ per day of spill.\ncaused losses amounting to 50% after 12 hours and\nAs in the prior scenario, these values are over-\n68% after 15 days.\nestimates because of the simplifying assumption\nThe oil slick resulting from the Ekofisk blowout\nof no current shear in the water column. With the\nconsisted of a sheen area that reached a maximum\nmore realistic assumption of the presence of tidal\nsize of some 3,000 km² and a thicker oil area of\ncurrents, the true concentrations could be an order\n500 km2 maximum extent (Audunson 1978; Haegh\nof magnitude lower.\nand Rossemyr 1980). Surface oil was observed over\na total area of about 55,000 km² during the event.\n9.2.3 Partitioning and Fate\nThe thicker slick was divided into streamers of\nThe partitioning of oil into the environment is\nemulsified oil some 10 m wide, 1-2 km long, and\ninfluenced by a number of competing processes\n1-20 mm thick; distances between streamers were\nin addition to advection and spreading. Most OC-\n100 m to 1 km in the central portion of the slick.\ncur at or near the sea surface, because the specific\nA fine structure of smaller streamers attributed to\ngravity of most crude and refined oils spilled at\nLangmuir surface circulation was also present be-\nsea does not exceed that of seawater and thus\ntween the heavier streamers.\ndirect sinking of petroleum residues is rare (Boehm\nBy the end of the blowout period stable water-\n1982). Evaporation, emulsification, sorbtion to\nin-oil emulsions had formed and erosion of the\nparticulate matter, microbial degradation, and\nedges of the streamers was underway. The erod-\nphotochemical oxidation are the major processes\ned matter initially consisted of 2-20 mm \"lumps,\"\ninvolved (Fig. 9.1). Their absolute and relative\nwhich gradually were reduced to 1-3 mm. The\nmagnitudes and rates (Fig. 9.2) will depend upon\nviscosity of the emulsified oil increased markedly\nthe specific chemical and physical properties of the\nafter 2 days at sea as a result of decreased water\npetroleum and on environmental factors such as\ncontent and probably evaporation and other\nturbulence at the sea surface, wind speed, air and\nweathering processes (Haegh and Rossemyr 1980).\nwater temperature, particle type and concentra-\nThe oil remaining at the sea surface 2 weeks after\ntion, light intensity, and microbial composition and\nthe blowout was stopped consisted of small lumps\nabundance. The reader is referred to Whittle et al.\n(Grahl-Nielsen 1978), which were also observed\n(1982) for a general review of petroleum fate in\n4-6 weeks after capping the wellhead. Some 115\nthe sea and to Malins (1977) and Payne and Jordan\ntons of oil remained on the sea surface by early\n(1979) for details on the degradation of petroleum\nJune, about 1 month after the blowout ended.\nin the subarctic marine environment.\nA survey of hydrocarbon-degrading bacteria in\nlate April-early May 1977 showed smaller than ex-\nFate of Oil From Well-\npected populations at the sea surface and higher\nDocumented Spills\nnumbers at depths of 5-10 m. The unweathered\nWell-documented oil spills provide insights into\noil at the sea surface was thought to have an in-\nthe likely fates of spilled oil in the Navarin Basin\nhibitory effect on the bacteria during the early\nunder various circumstances. Pertinent features of\nstages of the blowout.\nfour major events are summarized in Table 9.1.\nWater samples taken at 1-20 m in the water\nEkofisk Bravo blowout. Perhaps the closest\ncolumn under the oil slick generally had total\nanalog to a potential platform blowout in the\nhydrocarbon concentrations of 20-40 ug/liter. The\nNavarin Basin during the open-water season is the\nhighest values, up to 350 ug/liter, were obtained\nEkofisk Bravo event, which occurred in 1977 in\nnear the Ekofisk well the day after it was capped.","Oil & Gas Development & Issues\n115\nDistance From Blowout. km\nSW\nNE\n- 20\n- 10\n0\n10\n20\n30\n40\n50\n60\n70\n80\n90\n100\n0\n2.000\n1.000\n$10,000\n5\n5.000\n500\n1.000\n10\n15\n250\n100\n20\nND\n25\n20\n20\n5\n30\n5\n35\nOil Concentrations. ppb\n11 Li\n40\nR11\nP7 P5\nP11\nP8\nR7\nP14\nR6\nR5\nP2\nP9 P10\nP15\nP12\nP13\nR10\nR4\n(Vertical exaggeration 5,000 x\narea of concentration > 100 /;\n= area of concentration 5-100 ug/l)\n=\nFIGURE 9.8-Concentrations of oil along a transect oriented to the northeast of the Ixtoc I blowout, September\n1979. (Redrawn from Boehm and Fiest 1982.)\nSediment samples indicated that little Ekofisk\nthe spill, the investigators were still able to detect\noil reached the sea floor. All samples had less than\nthem in the clam Macoma balthica (Elmgren et\n8 ppm of hydrocarbons of possible Ekofisk origin\nal. 1983).\nand most contained less than 1 ppm (Johnson et\nAmoco Cadiz spill. This was one of the largest\nal. 1978).\nand best studied tanker spills in history. The\nTsesis spill. The tanker Tsesis spilled a relative-\nvessel's entire cargo was lost during a 2-week\nly small (about 1,000 t) amount of medium-grade\nperiod of extremely stormy weather and rough\nfuel oil in a semi-enclosed, low-energy setting\nseas. A rather complete accounting of oil fate is\nhaving little or no tidal variation and limited\navailable from this oil spill (Table 9.1). The amount\ncirculation. However, the water apparently was\nof oil incorporated into the water column in\nwell mixed at the time. Water depths were fairly\ndissolved and dispersed forms during the Amoco\nshallow, some 20-25 m, in the affected area. Of\nCadiz spill was greater than that observed during\nparticular interest in this event was the documen-\nother oil spills, evidently because of the very high\ntation of oil sedimentation to the bottom via sedi-\nwave energy which forced the oil into the water\nment traps. Also, although no petroleum residues\ncolumn. Hydrocarbons were observed as deep as\nidentifiable as of Tsesis origin could be found in\n75-100 m; concentrations were as high as 152 ng/g\nthe sediments by November 1980, 3 years after\n(Vandermeulen 1982).","ences*\n(1) Gundlach and Boehm 1981, (2) Gundlach et al. 1983, (3) Mackay et al. 1981, (4) Parrotte 1981, (5) Boehm 1982, (6) Kineman et al. 1980, (7) Elmgren et al. 1983.\n1. 2. 8\nRefer-\n1,3,\n4.5\n6. 7\n9\n1\nremoved by microbial\nOil detectable in very\nsorbtion, zooplankton\nMicrobial degradation\nMicrobial degradation\napparently limited by\n55-64% of total spill\nMaximum slick area\nMousse very rapidly\ncleaned from shore.\nLong persistence of\ninhibited in upper-\nSedimentation by\nlack of nutrients.\nlow quantities in\nwas 15,000 km².\nAbout 4% of oil\nComments\nformed in slick.\noil in estuaries.\nfecal pellets.\ndegradation.\nsediments.\nmost 6 m.\nrated Slick Column mented Stranded\n<1->2\nwaters)\n(U.S.\n28\n0\n64\nTrace\nSedi-\n8\n6\n2\nFate (%)\nTABLE 9.1-Parameters of selected major oil spills.\nWater\n13.5\n-\n-\n3\n33\n-\n-\n21\nburning)\nEvapo-\n(incl.\n30\n58\n68\n-\nQuantity\nLight Arabian 223,000\n476,000\n20,000\n> 1,000\n(t)\nIranian crude\nsome bunker\nOil\nLight crude?\n#5 fuel oil,\nType\nMedium\ncrude?\ncrude,\nextended period\nenergy offshore;\nEnvironmental\nsheltered bays,\nrelatively high\nlow energy in\nenergy; water\nVariable over\ncolumn verti-\nStormy. High\nPrevailing\nenvironment\ncally mixed\nLow-energy\nSetting\nApparently\nof the spill\nestuaries\n(8) Vandermeulen 1981, (9) Bates 1978.\nSwedish Baltic\nBrittany coast\nMexico; 48 m\nOffshore, Bay\nof Campeche,\ncoast; about\nwater depth\nLocation\n70 m water\n280 km off\nNearshore,\nNorth Sea,\nNorwegian\nNearshore,\nS. Gulf of\ndepth\nEkofisk Bravo\nAmoco Cadiz\n4/22-29/77\n10/26/77\nplatform\n3/16/78\nplatform\nblowout,\n6/3/79-\n3/23/80\nblowout\nIxtoc I\nVessel\nVessel\nEvent\nTsesis\nspill,\nspill,\n*","Oil & Gas Development & Issues\n117\nDue to the prevailing high-energy setting in the\nsurface flocculent layer) at the sea floor.\noffshore portions of the spill area, oil incorporated\nGundlach and Boehm (1981) examined the fates\nin subtidal sediments there was rapidly removed.\nof oil following six major spill events (Santa Bar-\nThis was not the case in many of the sheltered\nbara blowout, Arrow spill, Argo Merchant spill,\nestuaries and embayments along the adjacent\nTsesis spill, Amoco Cadiz spill, and Ixtoc I\ncoast. Oil laid down in low-energy, fine-sediment.\nblowout). Their analysis produced the following\nsubtidal areas was still evident in June 1981, more\nranges which can serve to bound the various oil\nthan 3 years after the spill event. In the intertidal\ndegradation processes that might be expected to\nzone a large fraction of the stranded oil was rapidly\nbe significant in the event of an oil spill in the\nremoved by wave and tidal action, cleanup opera-\nNavarin Basin:\ntions, and microbial activity. However, oil that\nObserved\nentered low-energy marshes was very persistent.\nFate\nRange (%)\nOil buried in anaerobic layers and in asphalt-like\nEvaporation\n20-40\npatches in the intertidal zone is expected to remain\nIncorporation in water column\n0.02-9\nfor years.\nDeposited in bottom sediments\n0.1-8\nIxtoc I blowout. A large body of information\nOil on shoreline (depends\non the fate of oil was generated during the extend-\nstrongly on location)\n0-28\ned Ixtoc I platform blowout, the largest oil spill in\nhistory. A large fraction of the oil released burned\nPossible Fate of Oil Spilled\nin the immediate vicinity of the platform; relatively\nIn the Navarin Basin\nlittle was recovered. Detailed observations were\nmade of oil concentrations in the water column\nJudging from the foregoing, it can be expected\nunder the slick emanating from the blowout.\nthat for an event involving a medium-weight crude\nObserved values of hydrocarbon compounds larger\noil such as Prudhoe Bay crude during the open-\nthan C10 ranged from 10,600 ug/liter within a few\nwater season, a major fraction of the spilled oil\nhundred meters of the platform to 5 ug/liter about\nwill be removed within a few days by evaporation.\n80 km distant (Fig. 9.8; Boehm and Fiest 1982).\nThe rate of evaporation will depend on the oil's\nThe highest concentrations occurred within 25 km\ncomposition, wind speeds, the slick's area, and air\nof the platform and within the uppermost 6 m of\nand water temperatures. The evaporative losses\nthe water column. The high concentrations near\nwill involve the more volatile aliphatic and\nthe platform were thought to be due to suspend-\naromatic components of the petroleum.\ned oil droplets in the water column. The concen-\nOil at the sea surface will be spread by gravita-\ntration of oil in the uppermost 20 m of the water\ntional forces, dispersion, and winds, eventually\ncolumn at all locations was attributed to the up-\nbreaking up into slicklets or streamers as in the\nward streaming nature of the subsurface blowout\ncase of the Ekofisk Bravo event. Water-in-oil emul-\nas well as the positive buoyancy of the oil droplets.\nsions (\"mousse\") will be formed; these will become\nBoehm and Fiest (1982) estimated that at any given\nprogressively denser and more viscous with time\ntime about 3% of the oil introduced from the\ndue to differential weathering of the petroleum\nblowout was present below the oil slick in the top\ncomponents. The non-volatile higher molecular\n20 m of the water column and that most of it was\nweight compounds remaining after evaporation,\nwithin 25 km of the wellhead.\nmicrobial degradation, and other partitioning pro-\nA relatively small fraction of the oil released dur-\ncesses have slowed likely will persist for some time\ning the Ixtoc I blowout reached the U.S. coastline.\nas a very slowly weathering mousse, then as tar\nIt is not known how much stranded in Mexican\nballs, and ultimately as small particles that are\nterritory. Much of the beached oil was in the form\neventually ingested by zooplankters and incor-\nof tar mats (Boehm et al. 1983), whose fate is\nporated into fecal pellets that sink to the sea floor\nbelieved to be breakup followed by distribution\nover an extensive area.\nof small tarry particles in surface and subsurface\nMicrobial degradation of spilled oil is expected\nwaters. A survey in subtidal waters (3-60 m depth)\nto be an insignificant process in the Navarin Basin.\nalong the Texas coast indicated Ixtoc oil was\nHaines and Atlas (1983) found low numbers of\nassociated with mobile sedimentary material (the\nhydrocarbon-degrading organisms in the northern","Navarin Basin Synthesis\n118\nthe relative immaturity of the experimental state\nBering Sea. apparently due to the absence of petro-\nof the art concerning oil-ice interactions. Obviously,\nleum pollutants in the region.\nthe oil-ice spill situation presents a more complex\nSome oil will enter the water column in dissolved\npicture than an open-water situation. The spectrum\nform and some as droplets. The quantity intro-\nof potential scenarios is large, varying according\nduced will depend on the turbulent energy avail-\nto the particular circumstances of spill location,\nable to drive the oil downward via wind and wave\nice coverage, morphology, and structure, prevail-\naction. The effect of dissolution of oil into the water\ning weather conditions, time of year, and myriad\ncolumn will be insignificant in terms of the total\nmass balance of the oil slick, as demonstrated by\nother factors.\nIn general it may be anticipated that the seaward\nPayne et al. (1983). The extent of sorbtion of crude\nside of the marginal ice zone (MIZ) might be char-\noil to suspended particulate matter will depend\nacterized by high dynamic energy levels, small floe\nupon the concentration of oil and its chemical\nsize, and large volumes of brash ice, as compared\nproperties and viscosity, the mineralogical compo-\nto the interior pack ice where floe sizes and cumu-\nsition and size distribution of the suspended matter,\nlative static forces may be very large, but the\ntemperature, and degree of mixing (Feely et al.\ndynamic energy levels relatively low. This was the\n1978). Experiments by Feely et al. (1978), Malinky\npattern noted by Reimer (1981) in the Labrador Sea.\nand Shaw (1979), and Payne et al. (1981) indicate\nMartin (1981) has categorized oil-ice interaction\nthat the moderately water soluble and dispersed\nprocesses in the Bering Sea as those that capture\nfractions of oil are more readily accommodated\noil and those that transport it. Processes that cap-\nby particulate matter than the very soluble com-\nture oil include the interaction of oil with smooth,\nponents. Also, Payne et al. (1981) have shown that\nunbroken, first-year ice and by grease and pancake\nthe availability of oil for accommodation to\nice, as well as the interaction of ocean swell, oil\nsuspended particulate matter falls off rapidly as\nand the ice floes at the ice edge. Processes that\nit weathers. They found that oil/micell formation\ntransport oil include the interaction of oil with\nand dispersions in the water under experimental\nLangmuir circulation in lee-shore polynyas where\nslicks diminished rapidly after 12-24 hours.\ngrease ice is found, the general advection of oil\nTherefore, it can be speculated that the \"proper\"\nby large-scale ice movement, and specific advec-\ntype of suspended matter must be present near\ntion of oil by the bands of ice found at the ice edge\nthe spill site if significant amounts of unweathered\nduring periods of off-ice winds. Observations of the\noil are to reach the sea floor, and that the highest\nBuzzards Bay oil spill of January 1977 suggest that\nconcentrations of oil at the bottom would occur\noil trapped in sea ice may be carried distances on\nnear the spill site. Given the water depths in the\nthe order of hundreds of kilometers before being\nNavarin Basin and its remoteness from sources of\nreleased when the ice melts (Martin 1981). In the\nparticulate matter, it appears improbable that\nNavarin Basin region it can be anticipated that\nmuch oil will rapidly reach the sea floor via sorb-\nmost oil would be released over the continental\ntion to suspended matter and sinking. Some oil\nshelf, as ice penetration over the deep basin of the\nmay be sedimented through incorporation into\nBering Sea is infrequent and limited.\nzooplankton fecal pellets.\nIn the event of an oil spill beneath a wind-\nIn the event oil reaches St. Matthew Island, its\nagitated field of pancake ice (as might be found\npersistence there likely will be brief. The exposed\nin the MIZ), a sizeable fraction of the oil will be\nnature of the island's coastline, its rocky geomor-\npumped out on the ice surface and the remainder\nphology, seasonal high wave energy prevalent in\nwill be incorporated into the grease ice/pancake\nthe intertidal zone (suggested by wind data of\nsystem (Martin 1981). Also, observations of swell\nBrower et al. 1977), and/or ice abrasion are in-\npropagation through fields of ice floes near the ice\ndicative of rapid removal based on evidence from\nedge and observations of wetted surfaces on these\nspill events such as the Amoco Cadiz event (Hayes\nfloes strongly suggest that similar pumping of oil\net al. 1979; Gundlach et al. 1983).\ninto floe surfaces will occur in this situation.\nInferences about the possible fate of oil spilled\nOil spilled under tight pack ice will remain sta-\nin the Navarin Basin during the presence of sea\ntionary until the current in the underlying water\nice are tenuous due to the near absence of docu-\nreaches 15-25 cm/s relative to the ice, at which\nmentation of oil spills in ice-infested waters and","Oil & Gas Development & Issues\n119\ntime it will begin to move (Cox and Schultz 1981).\nAn oil spill event in the vicinity of St. Matthew\nMean ice drift rates of 25 cm/s and maximum rates\nIsland could result in the intertidal zones of that\nof 65 cm/s in the Navarin Basin (see Chapter 3)\nand neighboring islands being contaminated by\nsuggest oil may move relative to the ice on occa-\nunweathered oil. However, given the geomorph-\nsion. Pease et al. (1983) measured mean vector\nological character of the islands' intertidal zones\nvelocities of about 15 cm/s 1.1 m below a free-\nand the prevalent high wave energy there, oil\ndrifting ice floe when the concurrent observations\nwould not be expected to persist very long.\nof floe and wind velocities were about 30 cm/s and\nAn oil spill event during the season when ice\n9 m/s, respectively. At lower speeds, the areal\nis present in the Navarin Basin could have a variety\nextent of the spill will be substantially less than\nof outcomes, depending upon the time of year,\nthat resulting from an open-water spill of the same.\nlocation, and prevailing weather, among other\nvolume.\nfactors. If the spill occurred in the open water out-\nThe fate of oil trapped under ice will depend\nside the pack ice, the fate of oil probably would\nupon a number of factors. If brine channels are\nbe comparable to that during the ice-free period\npresent or form within the ice, oil can migrate\nexcept that the dominant direction of transport\nupward through the channels; or oil may be in-\nwould be southwestward, into the deep basin of\ncorporated in forming ice. An ice cap over the oil\nthe Bering Sea. A spill occurring in close pack ice\nprevents evaporation, thus dissolution may be a\nlikely would persist for an extended period due\nmore significant process under these conditions\nto the lower ambient wave and wind energy levels\nthan when oil is exposed to the atmosphere.\nacting to disperse and evaporate the petroleum,\nOil spilled between floes within the pack ice also\nand the physical containment of the oil by ice. Oil\nmight be expected to persist longer than in open\nreleased under the ice could remain there or move,\nwater due to the cold temperatures, low turbu-\ndepending upon the speed of the ice relative to\nlence, and restricted spreading-all of which would\nthe underlying water.\ntend to hinder evaporation at the surface of the\nThe time of occurrence of an oil spill in sea ice\nslick and other active processes. Reimer (1981)\nwould be influential in its fate. A spill during early\nobserved that, in general, dispersion processes\nwinter could result in significant incorporation of\nwere very slow in the ice environment of Cabot\noil in ice, extended oil persistence, and concomi-\nStrait during the Kurdistan spill of 1979 as com-\ntant long transport before release. Because sea ice\npared to those in open water.\nin the Navarin Basin normally is restricted to the\nIn summary, the foregoing analyses indicate that\ncontinental shelf, the ultimate release of oil from\nan oil spill event during the open-water season in\nice likely would occur over the shelf.\nthe Navarin Basin would result in predominantly\nnortheastward advection of the oil, with con-\n9.3 HAZARDS TO DEVELOPMENT\nsiderable scatter about the mean direction. Given\nthe available information about winds in the\nOCS oil and gas development in the Navarin\nregion, the speed of the resultant slick would be\nBasin will require consideration of means to cope\nabout 13 km/d. It is probable that spreading and\nwith a number of environmental hazards. Potential\ndispersion would result in the rapid breakup of the\nhazards include seismicity and ground shaking,\nslick into patches. The high energy levels prevalent\nactive faulting, unstable sediments, sea ice, winds\nat the sea surface in the region would promote\nand waves, superstructure icing, and tsunamis.\nmousse formation and evaporation would active-\nTheir significance depends on location and the par-\nly decrease the mass of the slick. Dissolution and\nticular activity affected.\nsorbtion of oil into the water column would be of\n9.3.1 Geologic Hazards\nlesser importance in decreasing the slick's mass,\nwhile microbial degradation and photo-oxidation\nSeismicity and ground shaking do not appear\nlikely would be insignificant. The likely sequence\nto be significant hazards in the Navarin Basin given\nof events would be much like that observed during\nthe observed lack of major earthquakes there.\nthe open-water Ekofisk spill, when after a couple\nHowever, if support bases, onshore processing\nof weeks, little other than small tar balls remained\nfacilities, or transshipment terminals are construc-\nat the sea surface.\nted on the seismically active Alaska Peninsula or","Navarn Basin Synthesis\n120\nmarine canyons are potential problems if in fact\nin the eastern Aleutian Islands. earthquakes and\nthey are active features. Activity should be ascer-\nassociated tsunamis pose a considerable threat.\ntained prior to siting any structures there.\nThere is a high likelihood that a great (M > 7.7)\nGas-charged sediment is probably the major\nearthquake will occur in that region within the\nconcern as a potential geological hazard in the\nlifetime of any OCS activity. Available evidence\nNavarin Basin, especially in the northern two-\nsuggests that the stress building in the Shumagin\nthirds of the region (Carlson et al. 1982). Sediment\nseismic gap will be released in the form of a great\nshear strengths and bearing capacities in gas-\nearthquake within the next 10-20 years (Sykes et\ncharged sediments may be lower than those in gas-\nal. 1980; Jacob 1983). The rupture length of such\nfree sediments. Sediment failure can occur if\nan event may be of the order of several hundred\nbubble-phase gas increases due to cyclic loading\nkilometers, thus affecting a very large portion-if\nor drilling into such sediment. Such failure could\nnot the entirety-of the region where shore-based\nadversely affect pipelines or production platforms.\nfacilities are likely to be sited. In addition to the\nstrong ground shaking, a tsunami with runup\n9.3.2 Ice Hazards\nheights of up to 30 m could be generated. There-\nSea ice in the Navarin Basin appears to be com-\nfore, design and siting decisions are crucial. More\nposed entirely of annual, or first year, ice. Annual\ndata on ground motions produced by strong re-\nice attains thicknesses of no more than about 1\ngional earthquakes are needed in order to refine\nm; as such, it poses no extraordinary hazard for\nseismic exposure assessments (Woodward-Clyde\nfixed structures. Production platforms in Cook Inlet\nConsultants 1982; Jacob 1983) and to develop\nhave contended with comparable ice for many\nadequate structural design criteria.\nyears (Jahns 1980). First-year ridges, however,\nActive faulting in the Navarin Basin is a poten-\npresent a more formidable challenge. The sparse\ntial threat to bottom-founded structures such as\ninformation in the public domain indicates such\nproduction platforms and pipelines. The currently\nridges may attain thicknesses of 18-30 m (Jahns\navailable non-proprietary seismic reflection data\n1980; Anon. 1982a). Production platforms used in\nfrom the region are of limited value in assessing\nthe Navarin Basin likely will incorporate various\nfaulting because trackline spacing of about 30 km\ndesign features to reduce large overturning\nrestricts interpretation of fault length, orientation,\nmoments created by the combination of deep\nand age. Faults observed to cut Holocene sedi-\nwater and the lateral pressures exerted by ice.\nments are considered to be active. Thus detailed\nCross-sectional areas will be minimized at the\nsurveys of sites selected for bottom-founded struc-\nwaterline and cones may be installed there to\ntures should be conducted to ensure that such\ncause ice to bend and fail in flexure. Gravity and\nfeatures are not present.\ntemplate platforms currently in use elsewhere can\nUnstable sediments also pose hazards to bottom-\nbe suitably modified (see Jahns 1980).\nfounded structures. The instability can take several\nIce will pose formidable operational constraints\nforms. In the Navarin Basin evidence of submarine\nfor rig boats and other smaller vessels. They will\nsliding, sediment transport, and gas charging is\nprobably require strengthened hulls in order to\nwidespread. Submarine sliding appears to be re-\noperate safely. Ice-breaking capabilities may also\nstricted to depths greater than 150 m, but again\nbe desirable SO that they may contend with pres-\nwide track spacing makes identification of all such\nsure ridges and other heavy ice more readily.\nfeatures and interpretation difficult. Some sediment\nOil transport during periods of ice coverage will\nslide zones.are large and extend to sub-bottom\nrequire tankers with ice-breaking capabilities, such\ndepths of as much as 200-300 m (Karl and Carlson\nas the Manhattan. Also, if St. Matthew Island is\n1983). It is possible that the submarine slides are\nused as a forward support or loading area, a har-\nof Pleistocene age and that sedimentation rates\nbor will have to be created. The island has no\nthen were higher, which would make undercon-\nnatural sheltered anchorage. Offshore loading\nsolidation a relatively more important factor than\nunder sea ice conditions is problematical, as the\nevidenced by surficial sediment properties (Carlson\nappropriate technology to accomplish this activi-\net al. 1982). Most surficial sediments in the Navarin\nty has not yet been developed or tested.\nBasin are lightly to moderately overconsolidated.\nIce should not affect exploration phase activities.\nSand wave fields observed at the heads of sub-","Oil & Gas Development & Issues\n121\nExploratory drilling probably will be conducted\naffect operations to a considerable degree during\nduring the open-water season by drillships or semi-\nthe period from fall through spring when sea ice.\nsubmersible rigs.\nsuperstructure icing, large seas, and high winds\nSuperstructure icing will be a potential opera-\nare prevalent. Operational strategies will have to\ntional hazard for workboats and other smaller\nbe developed to deal with these conditions.\nvessels during much of the year according to re-\ncent analyses (Kozo 1983c). Under extreme icing\n9.4 IMPACTS ON FISHERIES\nconditions larger vessels and fixed structures such\nas production platforms also could be affected. The\nPrevious synthesis reports have summarized (or\nmoderate icing conditions likely from December\nreferenced) the results of numerous toxicity studies\nthrough April could easily promote dangerous ice\non the effects of oil on Alaskan and other species\naccumulations on smaller vessels. Extremely\nof fishes (Hameedi 1982; Thorsteinson 1984) and\ndangerous icing conditions are possible, given the\non fisheries (Rice 1981). Most laboratory assays\ncircumstances of minimum air and water temper-\nhave examined organism responses to exposures\natures and maximum ice extent during the period\nto water-soluble fractions of hydrocarbons and de-\nSeptember-February. Additional observational\ntermined the LD50, that dose that is lethal to 50%\ndata obtained during icing events are needed from\nof the population of test organisms. The LD50\nthe region to improve hazard assessments, counter-\nmay overestimate the magnitude and duration of\nmeasures, and forecasting (Kozo 1983c; W. Spring\nexposure. (In many test organisms, initially in-\npers. commun).\ncreasing hydrocarbon concentrations are respon-\nsible for the highest mortality rates and greatest\n9.3.3 Wind and Wave Hazards\nproportion of deaths in the LD50 determinations.)\nWind and sea conditions in the Navarin Basin\nHowever, it serves as a sensitivity index where\nappear to be comparable to those in the North Sea,\nif similar concentrations were experienced in a\nwhere the oil industry has operated for several\nreal spill situation, oil-induced mortalities could be\nyears. Experience gained in the North Sea and\nexpected. LD50's for many Alaskan fishes have\nelsewhere should aid in the planning and conduct\nbeen determined in static and flow-through assays\nof operations. The analyses of recent and historical\nusing the WSF of Cook Inlet and Prudhoe Bay\nwind data from the Navarin Basin region by Kozo\ncrudes. The results of the two laboratory methods\n(1983b) show that gale class or greater winds occur\nare not directly comparable (differences are similar\nmainly between October and March, when they\nto those expected under embayment versus ocean-\nwere observed from 7.6 to 20% of the time. Dur-\ntype spills); however, ranges of lethal concentra-\ning the remainder of the year gales occurred less\ntions (in parts per million) for several ecological\nthan 2% of the time. Seventy-knot (about 35 m/s)\ngroupings of finfish by life stage have been com-\nwinds and 51-foot (15.5 m) seas were reported\npiled (Table 9.2).\nduring the drilling of a COST well in the Navarin\nMuch field and laboratory research has also been\nBasin in October 1983 (Anon. 1983). The observed\nconducted on the sublethal effects of hydrocarbon\nsea heights are consistent with the maximum ex-\ncontaminants on marine organisms. Pertinent\npected values based on the hindcast wave statistics\nresults have been summarized in two recent Bering\nprepared by Kozo (1983a).\nSea synthesis reports (Hameedi 1982; Thorsteinson\nIn summary, the environmental hazards of the\n1984); they generally show that most organisms\nNavarin Basin do not appear to pose any extra-\nunable to avoid hydrocarbons will take them up\nordinary technological hurdles to OCS oil and gas\nfrom food, sediments, and surrounding waters.\ndevelopment (with the possible exception of off-\nOnce incorporated into tissues, these hydrocarbons\nshore loading during periods when sea ice is pres-\nand their metabolites can reduce an organism's\nent). The design and siting of a transshipment\nlongevity through a multitude of behavioral,\nterminal in the south Alaska Peninsula area will\nphysiological, or biochemical changes. Sublethal\npresent considerable difficulties due to the high\nexposures may be most detrimental to gonadal\nregional potential for a great earthquake and\ndevelopment and reproduction in marine species\nassociated damaging phenomena. The environ-\nvia potential alterations in metabolic or\nmental hazards in the Navarin Basin probably will\nchemoreceptory processes affecting growth or","122\nNavarin Basin Synthesis\nspawning activities, respectively. Any change that\na spill of this size indicate a maximum areal\njeopardizes a species' ability to search for, locate,\ncoverage of 1 km2 (assuming no slick breakup) or\nor capture food will affect its capability to main-\nan envelope of 10 km2 encompassing the contam-\ntain basal nutritional requirements and, over the\ninated zone if the slick loses its integrity via the\nlong term, life-supporting systems. This is especial-\nformation of slicklets. The latter situation is more\nly true of rapidly developing life stages such as lar-\nrealistic; therefore, under a worst case scenario,\nvae. Quantification of such impacts is not possi-\na 10,000-bbl spill would result in a 10-km2 contami-\nble; however, any longlasting effects of sublethal\nnant cloud possessing peak toxic concentrations\nexposures would pose a more serious problem\nof 50 ppb uniformly distributed throughout the\nfrom chronic pollution (e.g., Commencement Bay,\ncolumn after 12 hours. After this, concentrations\nWashington, versus the Navarin Basin). Low-level\nwould quickly decrease as the spill cloud would\nhydrocarbon accumulations resulting from brief\nbe moved through and diluted by \"clean\" seawater.\nexposures may be removed (secreted or excreted)\nA simplistic approach for predicting order-of-\nby an organism quite rapidly, in hours to days,\nmagnitude fish losses from an oil spill, with no\nwhereas depuration may require several weeks\nconsideration of ecological ramifications, requires\nafter prolonged exposures. Sublethal hydrocarbon\nthe ability to estimate egg and larval densities of\nexposure may increase stress levels, making a\nmajor species in impacted waters. The method\nspecies more vulnerable to predation or other\nfurther assumes a worst case situation; i.e., all eggs\nsources of mortality.\nand larvae exposed to contaminated waters will\nbe killed. For a 10,000-bbl oil spill in the Navarin\n9.4.1 Predicted Fish Losses From Oil Spills\nBasin this implies a total kill of eggs and larvae\nThe dynamics of a 10,000-bbl oil spill during\nin a 10-km2 contaminated zone. Hydrocarbon\nsummer months was a major topic of discussion\nconcentrations of 200 ppb are assumed to be\nat the Transport Workshop (Section 9.2). The\nuniformly distributed throughout the 10 km², cor-\nmovements of oil on the surface and through the\nresponding to peak values under the slick after 12\nwater column were described using trajectory\nhours. Given the increased sensitivity of early life\nmodeling, weathering algorithms, and analytically\nstages, widespread mortalities could be expected\ndetermined rates of dispersion and dissolution.\nin this zone. The loss of harvestable adults is\nCalculations of time-dependent concentrations of\nestimated using principles of replacement-stock\noil for a hypothetical spill in depths between 110\ntheory. The sources and types of biological infor-\nand 130 m indicate total hydrocarbon concentra-\nmation required in these computations are shown\ntions beneath the slick would peak at about 0.2\nin Table 9.3. Data limitations and assumptions\nppm after 12 hours. This corresponds to a water-\nemployed are indicated in the following rationale\nsoluble fraction (WSF) of roughly 500 ppb through-\nfor determining the extent of oil spill mortality to\nout the water column. Spreading coefficients for\nselected species inhabiting the Navarin Basin.\nBiological Information From NWAFC Surveys\nTABLE 9.2-Lethal concentrations (ppm) of petroleum\nAs noted in Chapter 6, at least 3 years of NMFS\nfor various life history stages and ecological groupings\nsurveys have provided partial areal and seasonal\nof fish and shellfish.\ncoverage of the Navarin Basin. The most exten-\nsive surveys were conducted in 1979, 1981, and\nEcological\nJuve-\n1982 and involved a cooperative effort between\nGroup\nEggs\nLarvae\nniles\nAdults\nthe United States and Japan. Winter data (Novem-\nber-March) have not been collected. Discussions\nFlatfishes*\n0.1-1\n0.1-1\n> 5\n> 5\nof seasonal impacts from hypothetical oil spills are\nSemidemersal fishest\n0.1-1\n0.1-1\n1-3\n1-3\nPelagic fishest\n0.1-1\n0.1-1\n1-3\n1-3\ntherefore restricted to fall, spring (winter distribu-\nCrabs\n?\n< 0.1-2\n1-4\n1-4\ntion and abundance are probably comparable to\nthose of spring), and summer periods based on\nSOURCE: Thorsteinson and Thorsteinson 1984.\nrelative species compositions observed in 1975,\nFlounders. soles.\n1976, and 1981 trawl surveys (Table 9.4). Winter-\nT Pollock, cods. sablefish.\n+ Salmon, herring, capelin, others.\nspring data were extrapolated from survey catches","Oil & Gas Development & Issues\n123\njust south of the Navarin Basin obtained during\nHowever, even though data are not continuous\nthe spring of 1976. The six species in the table\nfrom any one year, they probably reasonably\nrepresent 70.2, 81.0, and 97.7% of the total catch\nreflect actual species abundance given what is\nin 1975, 1976, and 1981, respectively.\nknown about the fishes' seasonal movements.\nTwo major assumptions were made for this com-\nPertinent biological features of each species' life\nparison of several years' data: (1) the relative\nhistory were obtained from literature sources,\nspecies abundance in the Navarin Basin during\nprimarily Pereyra et al. (1976), Morris (1981),\nspring 1976 was similar to that observed west of\nScience Applications, Inc. (1981), and Thorstein-\nSt. Matthew Island, and (2) the relative seasonal\nson and Thorsteinson (1984).\nabundance described from the past several years'\nSeasonal distribution. Distributional informa-\ndata realistically reflects present stock conditions\ntion for the major finfish species has been summar-\nfor the seasons considered. Obviously, good sea-\nized from observations made in the Navarin Basin\nsonal data are lacking from the Navarin Basin.\nand more broadly over the southeastern Bering\nSea (Table 9.5). Included is information on depth\nof occurrence, areas of localized concentration\nwhere oil spill vulnerability might be greatest, and\nTABLE 9.3-Sources and types of information used in\nseasonal and diel movements. These species are\noil spill damage assessment for selected finfish species\nof the Navarin Basin.\nall widely distributed across the Bering Sea shelf.\nReproduction. Spawning by each species\nNWAFC Resource Survey Data\noccurs over several months' time. Long spawning\nperiods and widespread egg and larvae dispersals\nBiological Data\ngreatly reduce the probability of a complete year\nAge and sex composition\nclass loss of any species from oil spills in the\nMaturity\nNavarin Basin (Table 9.6). Most data on the timing\nMean age of maturity\nof spawning for each species have been obtained\nLength-weight-age relationships\nfrom plankton samples collected in the southeast-\nMean length of mature females\nern Bering Sea in the area north of Unimak Pass.\nMean biomass of mature females\nFewer samples have actually been collected in the\nMean fecundity of mature females\nNavarin Basin.\nEstimated Population Parameters\nDistribution of eggs and larvae in the water\nPopulation size (numbers and biomass)\ncolumn. Information on the seasonal occurrence.\n% population mature\nvertical distribution, and longevity of early life\nNumber of mature females\nstages has been inferred from plankton collections\nTotal biomass of mature females\nobtained in the southeastern Bering Sea and Gulf\n% biomass of mature females\nof Alaska (Table 9.7). Species that possess demer-\n% relative seasonal composition (biomass)\nNWAFC Simulation Modeling\nBiological Information\nTABLE 1.4-Relative seasonal abundance (percentage\nResource survey assessments\nof total fish biomass) of major species inhabiting the\nEmpirical growth and population\nNavarin Basin based on 1975, 1976, and 1981 NMFS\nrelationships\nNWAFC demersal surveys.\nRecruitment\nMortality (natural, fishing)\nCommercial\nSpring\nSummer\nFall\nMigration\nSpecies\n(1976)\n(1981)\n(1975)\nFeeding\nWalleye pollock\n40.1\n63.0\n62.6\nSpawning\nPacific cod\n5.7\n15.0\n1.1\nTrophodynamics\nGreenland turbot\n5.5\n15.5\n5.3\nSimulated Parameters\nFlathead sole\n2.5\n4.0\n1.2\nTotal finfish biomass/km3 over \"shelf\" and \"deep\"\nRock sole\n2.9\n0.2\n0.01\nNavarin Basin waters\nYellowfin sole\n24.3\n-\n-","Navarin Basin Synthesis\n124\neastern, central, and northern sectors) considered\nsal eggs, such as Pacific cod. Greenland turbot, and\nto have uniform standing stock distributions over\nflathead sole, would be less vulnerable to surface\nhundreds of square kilometers. These simulation\nspills during this stage of development.\nresults correspond reasonably well with actual\nStock composition. Pertinent information on\nsurvey catches over similar size areas in the Ber-\nage- and size-specific characteristics of mature\ning Sea. Even though fish and shellfish biomasses\nfemales for central Bering Sea populations of each\nare not SO evenly distributed over the Navarin\nspecies is presented in Table 9.8. Other data have\nBasin, the simulations provide relative abundance\nbeen used to estimate the percentages of mature\nindices for broad regions of unsurveyed waters.\nfemales in populations from the Navarin Basin\nFurthermore, the simulation results allow compar-\nregion (Table 9.9).\nisons by depth zones in the oil spill impact analysis.\nNumerical Fisheries Simulations\nFor the central Bering Sea the fisheries model\nestimates total finfish biomasses of 27.3t/km2 for\nThe NWAFC has developed simulations to\n\"deep\" waters (depths > 200 m) and 32.7 t/km2\nestimate standing stock biomasses of fishes and\nfor \"shelf\" waters (depths < 200 m).\nshellfishes inhabiting the Bering Sea (Laevastu and\nSimulation estimates were assumed to approx-\nLarkins 1981). This technique uses existing fishery,\nimate natural standing stocks and species composi-\noceanographic, and ecological data and a multi-\ntions over the Navarin Basin (Laevastu and Larkins\nspecies approach to estimate harvestable levels\n1981). As reported, 1975 and 1976 survey results\nof commercial species (Laevastu and Marasco\n(Pereyra et al. 1976; Bakkala and Smith 1978) did\n1982). The simulation procedure is also useful in\nnot stratify catch results or biomass estimates by\nexplaining population changes based on environ-\ndepth. In those years trawls were hauled from\nmental anomalies, predation, and other mortality\nshallow waters (50 m) to depths exceeding 450 m.\ncomponents. Biomass values are calculated over\nIn order to make depth-related spill impact eval-\nvery broad expanses of the Bering Sea (i.e. south-\nTABLE 9.5-Seasonal distribution of selected finfish species, eastern Bering Sea.\nSeasonal\nLocalized\nDepths of\nSpecies\nMigrations\nConcentrations\nDistribution\nOccurrence (m)\nand Season\nWalleye pollock*\nBathymetric\nInfluenced by\nOuter shelf and slope\n160-300\nWinter\ncold years\nShelf\n90-140\nSummer\nPacific cod\nUnclear\nShelf and slope\nShelf and slope\n80-550\nWinter & summer\nGreenland turbot*\nW. St. Matthew I.\nBathymetric\n600-900\nSlope\nWinter\nShelf edge and slope\n200-700\nSummer\nFlathead sole\nBathymetric\nEastern shelf\nShelf and slope\n80-400\nWinter\n-\nShelf\n40-160\nSummer\nRock sole\nBathymetric\nOuter shelf and slope\nE. Pribilof Is.,\n100-300\nWinter\ncentral Bering\nShelf\n70-140\nSummer\nSea, N. Unimak I.,\nS. Nunivak I.\nYellowfin sole\nUnimak I., NW. and\nBathymetric\nShelf and upper slope\n100-270\nWinter\nInner shelf-Bristo! Bay\nSE. Pribilof Is.\n< 100\nSummer\n*\nDisplays diel movement.","Oil & Gas Development & Issues\n125\nTABLE 9.6-Spawning periods for selected finfish species of the Navarin Basin.\nSpecies\nJan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov.\nDec.\nWalleye pollock\nPacific cod\nGreenland turbot\nFlathead sole\nRock sole\nYellowfin sole\nuations, 1975 and 1976 survey data were assumed\npresented are sufficiently detailed to compute\nto have the same abundance compositions (per-\nestimated numbers of eggs per square kilometer\ncent relative biomasses) estimated in simulations\nfor the selected species in the Navarin Basin. The\nof fish standing stocks over \"deep\" and \"shallow\"\nunderlying assumptions that must be emphasized\nwaters (Table 9.10). These values are at best only\nare: (1) pollock, Pacific cod, Greenland turbot,\napproximations of nature and do not accurately\nyellowfin sole, rock sole, and flathead sole are\nreflect \"deep\" water abundances because of the\ntreated as representing the total finfish biomass\nreduced sampling effort beyond the shelf break.\nof the Navarin Basin (see Chapter 6); (2) relative\nSurvey data from 1981 in the Navarin Basin have\nabundance estimates of survey data are propor-\nbeen reported by depth strata (Sample 1982).\ntional to simulated relative biomass projections\nover deep (27.3 t/km2) and shelf waters (32.7\nAnalytical Procedures\nt/km2); (3) uniform standing stock biomass\nThe biological data and population parameters\nestimates approximate nature; and (4) all females\nTABLE 9.7 Vertical distribution of eggs and larvae of major finfish species by season.\nDepths of Occurrence (m)\nSpecies\nExistence\nSeason*\n0-50\n50-100\n100-150\n150-200\nWalleye pollock\nEggs\nPelagic\nSpring\nLarvae\nPelagic\nSummer\nPacific cod\nEggs\nDemersal\nSpring\nLarvae\nDemersal\nSummer\nGreenland turbot\nEggs\nDemersal\nFall\nLarvae\nPelagic\nFall\nFlathead sole\nEggs\nDemersal\nSpring\nLarvae\nPelagic\nSpring\nRock sole\nEggs\nDemersal\nSpring\nLarvae\nPelagic\nSummer\nYellowfin sole\nEggs\nPelagic\nSummer\nLarvae\nPelagic\nSummer\nSpring = 1 December-31 May: summer = 1 June-31 August; fall = 1 September-30 November","126\nNavarin Basin Synthesis\nTABLE 9.8-Mean female age, size, weight, and fecundity at maturity for selected\nfishes inhabiting the Navarin Basin.\nAge\nSize\nWeight\nFecundity\nSpecies\n(yr)\n(cm)\n(g)\n(x 10 superscript(3)\nWalleye pollock\n3\n30\n400\n100\nPacific cod\n4\n73\n2.020\n1,000-2,000\nGreenland turbot\n13-14\n70\n1,280\n25\nFlathead sole\n6\n29\n180\n50\nRock sole\n4-5\n22\n300\n200\nYellowfin sole\n9\n26\n252\n800\nof each species spawn each year. Step by step, the\neach species (Table 9.11).\n2) Estimated number of mature females by\ncalculations include:\ndepth stratum. The estimates of species\n1) Seasonal estimates of species biomass by\nbiomass per square kilometer (from step 1)\ndepth stratum. The relative abundance est-\nare multiplied by the percent biomass\nimates (percent biomass) for each species\n(from Table 9.10) are multiplied by simulated\nestimates of mature females of each species\nstanding stock estimates (total biomass of fin-\nin the Navarin Basin. The resulting female bio-\nfish per square kilometer), yielding estimates\nmass per square kilometer is divided by the\naverage biomass per mature female, giving\nof seasonal biomass per square kilometer for\nTABLE 9.9-Key growth parameters and calculations used in estimating densities of finfish eggs and larvae in\nthe Navarin Basin.\nWalleye\nPacific\nRock\nFlathead\nPollock\nCod\nSole\nSole\nMean female length (cm)\n30\n56\n30\n28\nMean female age at maturity (yr)\n3\n4\n6\n6\nMean female weight at maturity (g)\n400\n2,020\n300\n180\nPopulation size (x 106)\n805.5\n11.9\n58.5\n65.5\n% of mature fish\n46\n42\n97\n82\nNumber of mature fish (x 106)\n370.5\n5.0\n56.7\n53.7\n% of mature females\n46\n64\n53\n43\nNumber of mature females (x 106)\n211.2\n3.2\n30.1\n23.1\nMean biomass of mature females (t)\n0.0004\n0.002\n0.0003\n0.0002\nEstimated total biomass of mature females (t)\n84,480\n6,400\n9,030\n4,620\nEstimated total population biomass (t)\n174,731\n24,735\n12,565\n10,726\nMature female % of total population biomass\n48\n26\n72\n43\nMean biomass of mature females (t)/km2\nDeep\n9.2\n2.8\n0.23\n0.13\nShelf\n7.1\n2.1\n0.94\n0.47\nMean number of females/km2\nDeep\n23,000\n1,400\n767\n650\nShelf\n17,750\n1,050\n3,133\n2,350\nMean fecundity (No. eggs) at mean maturity\n437,137\n1.2\n106\n180,000\n53,000\nX\nMean number of eggs/km²\nDeep\n10.1 X 109\n16.8\n108\n1.4\n108\n3.5 X 107\nX\nX\nShelf\n7.8 X 109\n12.6 X 108\n5.6 X 108\n12.5 X 107","Oil & Gas Development & Issues\n127\nTABLE 9.10-Relative seasonal composition (percentage of total finfish biomass) of major\ncommercial finfish species inhabiting \"deep\" and \"shelf\" waters of the Navarin Basin, based\non 1975, 1976, and 1981 NMFS NWAFC demersal surveys.\nSpring\nSummer\nCommercial\nFall\nSpecies\nDeep\nShelf\nDeep\nShelf\nDeep\nShelf\nWalleye pollock\n70.4\n44.9\n59.6\n63.6\n86.3\n89.9\nPacific cod\n10.4\n6.3\n6.9\n24.5\n1.4\n1.6\nGreenland turbot\n14.8\n5.3\n31.0\n6.7\n11.6\n6.5\nFlathead sole\n1.1\n3.4\n2.1\n0.6\n0.7\n2.0\nRock sole\n0.9\n3.9\n0.4\n0.3\n-\n-\nYellowfin sole\n34.1\n-\n-\n-\n-\n-\nNOTES: \"Shelf\" waters are those < 200 m in depth. \"Deep\" waters are those > 200 m in depth.\nPacific Ocean perch was considered a major commercial species in the Navarin Basin when this table\nwas generated, but was subsequently dropped due to lack of abundance of sensitive life stages during\nopen-water months. Totals, therefore, do not necessarily reflect 100% species composition.\nThe lower total for summer reflects the absence of arrowtooth flounder in this table. This species\nwas abundant in the catch in 1981.\nan average number of mature females by\nGreenland turbot are fall spawners; this essen-\nspecies in each depth stratum (Table 9.12).\ntially obviates any potential impacts to early\n3) Estimated numbers of eggs for each\nlife stages from summer oil spills. Yellowfin\nspecies by depth stratum. The average\nsole undergo extensive seasonal migrations\nnumbers of mature females per square kilo-\nfrom deeper (continental slope) waters in\nmeter (from step 2) are multiplied by average\nwinter to shallow depths (<50 m) in summer.\nfecundities for each species, which provides\nThis bathymetric movement is associated\nan estimated number of eggs by species\nwith feeding and spreading migrations. Also,\n(Table 9.12). Greenland turbot and yellowfin\nyellowfin sole spawn in greatest concentra-\nsole were excluded from consideration in egg\ntions in early summer just west of Nunivak\ndensity calculations. Greenland turbot, al-\nIsland, a considerable distance from the\nthough widely dispersed in the Bering Sea,\nNavarin Basin. Thus they are not likely to be\nare apparently more abundant in deeper\nimpacted by oil spills originating in the latter\nwaters than in the shelf or upper slope\nregion.\nregions where OCS development would likely\nLarval densities were also estimated for\noccur in the Navarin Basin. Additionally,\npollock, Pacific cod, rock sole, and flathead\nTABLE 9.11 -Seasonal - biomass estimates (t/km2) of major commercial finfish species\ninhabiting \"deep\" and \"shelf\" waters of the Navarin Basin.\nSpring\nSummer\nFall\nCommercial\nSpecies\nDeep\nShelf\nDeep\nShelf\nDeep\nShelf\nWalleye pollock\n19.2\n14.7\n16.3\n20.8\n23.6\n29.4\nPacific cod\n2.8\n2.1\n1.9\n8.0\n0.5\n0.5\nGreenland turbot\n4.0\n1.7\n8.5\n2.2\n3.2\n2.1\nFlathead sole\n0.3\n1.1\n0.6\n0.2\n0.2\n0.7\nRock sole\n0.3\n1.3\n0.1\n0.1\n-\n-\nYellowfin sole\n11.2\n-\n-\n-\n-\n-","Navarin Basin Synthesis\n128\nmasses and natural levels of mortality in our\nsole (Table 9.12). Mortality from egg to larval\napproach, a 10-km2 zone of contamination in the\nstages was assumed to be 99%.\nNavarin Basin would correspond to the egg and\nOil Spill Assessment\nlarval mortalities shown in Table 9.13. Clearly,\npollock eggs and larvae would incur the greatest\nThe \"worst case\" scenario of a 10,000-bb] instan-\nlosses, followed in order by Pacific cod. rock sole,\ntaneous oil spill in the Navarin Basin consists of\nand flathead sole.\na 10-km2 contaminant plume with hydrocarbons\nWith respect to potential losses to each fishery,\nevenly distributed throughout the water column\nassuming sizes at age of first spawning and recruit-\nat 200 ppb after 12 hours. After this time hydro-\nment to the fishery are similar and that for each\ncarbons would be quickly dispersed. Laboratory\nspawning unit one egg will survive to reproduc-\nstudies indicate that juvenile and adult fin- and\ntive age, the indicated mortalities would translate\nshellfishes briefly encountering such hydrocarbon\nto adult losses at replacement as shown in Table\nexposures would not be killed. For organisms\n9.14. Although these numbers appear large, they\nunable to avoid sublethal exposures, contaminants\nmust be considered in terms of the small total area\nin tissues and fluids would be quickly depurated.\nimpacted by the hypothetical spill relative to the\nEggs and larvae would suffer the highest mortal-\ntotal area of the Navarin Basin and southeastern\nity rates due to their fragile nature and inability\nBering Sea where these species are widely distrib-\nto avoid contamination. For the sake of discussion,\nuted. The 10-km2 spill zone would encompass\n200 ppb soluble fractions were assumed capable\n1/14,000 of the Navarin Basin and roughly\nof killing all eggs and larvae after 12 hours of\n1/40,000 of the southeastern Bering Sea. Assum-\nexposure. Deaths would either be immediate or\ning that spawning biomasses and products are\ndelayed, due to hydrocarbon-induced behavioral,\nuniformly distributed over much of these areas,\nmorphological, or biochemical changes. Given the\nthe species' reductions would be insignificant in\nassumptions of uniformity in standing stock bio-\nTABLE 12-Estimated numbers of females, eggs, and larvae per square\nkilometer for four finfish species inhabiting the Navarin Basin.\nSpring-Summer\nWinter-Spring\nDeep\nShelf\nSpecies\nDeep\nShelf\nWalleye pollock\n23,000\n17,750\nFemales\nEggs (x 106)\n10,100\n7,800\n101\n78\nLarvae (x 106)\nPacific cod\n1,400\n1,050\nFemales\nEggs (x 106)\n1,680\n1,260\n16.8\n12.6\nLarvae (x 106)\nFlathead sole\n650\n2,350\nFemales\n125\nEggs (x 106)\n35\n3.5\n1.25\nLarvae (x 106)\nRock sole\n3,133\nFemales\n767\nEggs (x 106)\n140\n560\n1.4\n5.6\nLarvae (x 106)\nNOTE: Winter-spring and spring-summer seasons are considered because spawning is\ninitiated during winter months by these species. Growth through larval stages extends\ninto late summer. (See text for more detail.)","Oil & Gas Development & Issues\n129\nterms of total population numbers in the Navarin\nutilization of cod quotas in other Alaskan areas;\nBasin or the eastern Bering Sea. Since commercial\n(2) strong markets; (3) good stock conditions; (4)\nfishing and survey effort vary considerably from\nfinancing support; (5) favorable management: and\nyear to year, as do rates of survival among species\n(6) the development of the pollock fishery. Any\nand life stages, such oil spill losses would not be\nfisheries for flatfishes will probably be directed\nrecognizable in catches or biomass estimates.\ntoward turbot or arrowtooth flounder. Again, devel-\nopment of a flounder fishery will be influenced\n9.4.2 Socioeconomic Impacts of OCS Devel-\nby trade barrier reductions, full use of quotas\nopment on Navarin Basin Fisheries\nelsewhere, a Japanese-U.S. joint venture, reduced\nFisheries impact assessments for the Navarin\nboat construction costs, and resolution of pro-\nBasin are based on the assumption of a gradual\nhibited species by-catch problems.\ntakeover of the groundfish fishery there by\nAt full strength, the domestic groundfish fleet\nAmerican fishermen during the next two decades.\nwould be composed of about 152 large (> 30 m)\nThis is an optimistic assumption. Large-scale entry\ntrawl and longline vessels and 29 domestic and\nof domestic fishermen into the pollock fishery will\nforeign processing vessels. The latter would be\ndepend on several factors, such as: (1) Japanese\nabout 90 m long. Perhaps 925 people would be\nremoval of import restrictions; (2) more favorable\nemployed on the catcher vessels and 1,740 on the\neconomic conditions for purchase or lease of the\nprocessor vessels. Most Navarin Basin fishes would\nlarge vessels required for the fishery; (3) a con-\nbe processed at sea due to the great distance from\ntinuation of the depressed condition of crab stocks;\nport and quality control concerns.\nand (4) encouragement of Japanese-U.S. joint\nIt is assumed that onshore processing plants\nventures to produce surimi (Anon. 1982b).\nwould also have to be developed on Unalaska\nDevelopment of a cod fishery will require: (1) full\nIsland to handle portions of the domestic ground-\nfish catches. Given the level of fishing activity\ndescribed above, local resident employment in this\nindustry would rise by 1,382 persons between\nTABLE 9.13-Estimated finfish egg and larval mortality\n1982 and 2000.\nover a 10-km2 zone of hydrocarbon contamination in\nAt the time of the Navarin Synthesis Meeting,\nthe Navarin Basin.\nassessments of possible socioeconomic impacts on\nthe fisheries of the Navarin Basin due to OCS oil\nEggs (billions)\nLarvae (millions)\nand gas development had not yet been completed.\nDeep\nShelf\nDeep\nShelf\nThe assessments will consider loss of catch, labor\nWalleye pollock\n101.0\n78.0\n1,010\n780\nimpacts, gear loss, collision impacts, and port im-\nPacific cod\n16.8\n12.6\n168\n126\npacts. Preliminary results of analyses of potential\nRock sole\n1.4\n5.6\n14\n56\nimpacts on Unalaska suggest minor impacts on the\nFlathead sole\n0.35\n1.25\n3.5\n12.5\narea due to its use as a marine support base.\nThe development scenario results for the mean\ncase Navarin Basin oil find indicate a 2% increase\nin population in the Aleutian Islands Census Divi-\nTABLE 9.14-Estimated losses at replacement of\nfishable adults over a 10-km2 zone of hydrocarbon\nsion over the \"without OCS case\" (Knapp 1982).\ncontamination in the Navarin Basin.\nMost of the projected doubling of population from\n4,208 in 1981 to 8,822 in 2000 is attributable to\nDeep\nShelf\nthe growth of the groundfish industry.\nWalleye pollock\n460,000\n355,000\n9.5 MARINE BIRD ISSUES\nPacific cod\n28,000\n21,000\nRock sole\n15,340\n62,660\nOil and gas development in the Navarin Basin\nFlathead sole\n13,000\n47,000\nhas the potential for affecting marine birds through\nTotal losses:\n516,340\n485.660\n=\noil spillage and human interference.","130\nNavarin Basin Synthesis\n9.5.1 Oil Effects\nblood cells. Holmes and Cronshaw (1977) subjected\nIn subarctic regions such as the Navarin Basin\nMallards fed oil-contaminated food to cold stress;\nand Bering Sea in general, oil may persist longer\nthey showed increased mortality over controls fed\nthan in more temperate waters due to slower\nuncontaminated food. Reproduction of Mallards\nevaporative and other degradative processes\nfed oil-contaminated food also is affected.\n(Schumacher 1982c). Its persistence increases the\nCavanaugh et al. (1983) found that their reproduc-\nexposure risk to seabirds and other biota. Large\ntive cycle is significantly lengthened. hatchability\noil spills from tanker accidents or well blowouts\nof eggs is lowered, and fewer ducklings are pro-\nare perceived by many as the major threat to ma-\nduced per breeding pair. Impaired adrenocortical\nrine birds from OCS oil and gas activities; however,\nand gonadal functions are evident in Mallards\nsuch events are infrequent. Chronic. smaller-scale\neating petroleum-contaminated food (Gorsline and\nspillage from tanker loading, unballasting, drilling\nHolmes 1982).\nof wells, and other operations is more prevalent.\nThe vulnerability of marine birds to oil varies\nEven small spills have the potential to kill large\nas a function of individual species' behavioral and\nnumbers of seabirds in certain circumstances, such\nother attributes. Alcids and sea ducks are con-\nas when birds are concentrated at colonies or in\nsidered to be more vulnerable than most groups\nwintering areas. An estimated 100,000 seabirds\nbecause they are gregarious, spend much time on\ndied near Kodiak Island in the winter of 1970; the\nthe sea surface, and dive when disturbed. Further,\nmortalities were attributed to oiling from ballast\nalcids-in common with many other seabirds-\ndumped by tankers en route to Cook Inlet oil ter-\nhave low reproductive rates, which would lengthen\nminals (Ohlendorf et al. 1978).\npopulation recovery time after a mass mortality.\nOil may affect birds through contamination of\nDue to their gregarious nesting habits, they are\nplumage. When their plumage is oiled, they lose\nespecially vulnerable if an oil spill occurs near a\nbuoyancy and are susceptible to drowning. Oiling\ncolony. Hunt et al. (1981c) found consistently high\nalso reduces the feathers' insulating properties. The\ndensities of several nesting seabird species within\nmetabolic imbalance induced (cf. Lambert et al.\n60 km of the Pribilof colonies. High bird densities\n1982) may cause death by hypothermia. In com-\nare also consistently encountered in preferred\nbination with severe environmental conditions\nforaging areas such as along the continental shelf\neven a minute amount of oil can prove fatal to\nedge and in passages between islands.\nseabirds (Levy 1980). Finally, breeding seabirds\nThe vulnerability of marine birds also has a\nencountering oil on the sea surface may transfer\ntemporal component. Thus colonial seabirds are\noil from their feathers to eggs they are brooding.\nmost vulnerable from early spring through autumn\nSmall amounts of fresh oil on eggs have been\nwhen they are tied to breeding colonies. Most sea\ndemonstrated to cause death of embryos in some\nducks and other waterfowl are invulnerable dur-\nseabird species (Holmes and Cronshaw 1977;\ning summer as they are dispersed at inland nesting\nPatten and Patten 1979).\ngrounds. However, large local concentrations may\nOil ingestion also poses possible problems to\nbe present during periods of molt or migration or\nseabirds. Some species, such as fulmars and storm-\nwhile on wintering grounds.\npetrels, are actually attracted to oil slicks (Boersma\nThe consequences of an oil spill near a seabird\n1983) and ingest the oil. Ingestion may cause direct\ncolony were examined via computer simulation\ntoxic effects. increased stress, and decreased\nby Wiens et al. (1979). A number of mortality\nreproductive success. Miller et al. (1982)\nscenarios for Black-legged Kittiwakes and Thick-\ndemonstrated that the higher molecular weight\nbilled and Common Murres at the Pribilof Islands\naromatic subfraction of Prudhoe Bay crude was\nwere employed to examine population responses\nresponsible in reducing weight gain in young\nto a one-time event. Murre populations were found\nHerring Gulls (Larus argentatus). Leighton et al.\nto recover more slowly than the kittiwakes, a\n(1983) showed that the hemolytic anemia devel-\nreflection of lower fecundity or adult survival. It\noped in young Herring Gulls and Atlantic Puffins\nwas also apparent from the simulations that deaths\nfollowing oral dosing with Prudhoe Bay crude was\nof adult birds are much more significant in terms\ndue to oxidative chemical processes damaging red\nof population-level effects than deaths of chicks","Oil & Gas Development & Issues\n131\nor subadults. Increases in recovery time produced\nhave implications for effects on seabirds that can\nby a decrease in survival rates of Thick-billed\nbest be categorized on a geographic basis. Because\nMurres are larger than the decreases produced by\nthe St. Matthew Island area has perhaps 20% of\na corresponding increase in survival rates. A 1%\nthe Bering Sea's nesting seabirds, the primary\ndecrease in survival produced a 4-fold increase in\nconcerns there center around the protection of the\nrecovery time, while a 1% increase only resulted\ncolonies and associated foraging areas. Most\nin a 1.7-fold decrease in recovery time. Wiens'\ncrucial are the colonies at Hall and Pinnacle islands\nmodel results indicate that Thick-billed Murre\nand those at either end of St. Matthew Island, as\npopulations would not recover if annual adult sur-\nwell as the waters surrounding the ends of the\nvival decreased by more than 1.3%. Thus a long-\nlatter island. Although no significant fraction of\nterm, low-level increase in mortality may damage\nthe world population of any species is present-\na population more severely than a short-term\nas is the case at the Pribilofs, Fox Islands, and\ncatastrophe.\nIzembek Lagoon-up to 30-40% of the Alaskan\nbreeding population of Northern Fulmars and\n9.5.2 Disturbance Effects\n10-15% of the murres nest there, in addition to\nRegional bird populations also may be affected\nlarge numbers of Crested and Least Auklets. The\nby various other forms of human interference.\nfew data currently available on local foraging\nAdverse impacts on nesting birds may result from\nareas showed consistently high seabird densities\ndisturbance. The degree of impact is difficult to\nin summer near St. Matthew Island (Eppley and\nquantify, being a complex function of individual\nHunt 1984, Fig. 9.9). Observations from the Pribil-\nspecies responses and the exposure regime (see,\nofs suggest that the waters within 60 km of the\nfor example. Strauch and Hunt 1982). Panic flights\nislands probably have high concentrations of birds.\nby cliff-nesting seabirds can result in eggs and\nDuring the breeding season, from April through\nchicks being knocked off ledges. Eggs and chicks\nSeptember, efforts should be made to avoid air-\nmay be exposed to predation when adults are\ncraft disturbances or other activities in the vicinity\nfrightened away. Certain waterfowl species, such\nof the St. Matthew seabird colonies. The frequent\nas Snow Geese, have been shown to be sensitive\nfogs at St. Matthew Island during summer may\nto aircraft and other noise (U.S. Department of the\nprove troublesome. as aircraft may be forced to\nInterior 1979). Disturbances on waterfowl nesting\noverfly colonies (A. Sowls pers. commun.). The\nor staging grounds may decrease breeding suc-\nCape Upright Flats at the east end of St. Matthew\ncess or fitness for migration.\nIsland appear to be the preferred location for a\nSeabirds can be indirectly impacted through\nforward support base (A. Sowls pers. commun.).\ntheir food supply. Stresses induced by need to\nSiting of facilities there may cause displacement\nforage longer due to lowered prey availability may\nof Snow Geese and other waterfowl, which in\naffect both nesting success and survival.\nspring use the open areas of the island for forag-\nAlthough oil-related impacts on marine birds due\ning while en route to their nesting grounds.\nto OCS oil and gas development in the Navarin\nThe oil spill model predictions suggest that oil\nBasin may not be sufficient to bring about popula-\nspilled in the Navarin Basin planning unit would\ntion level declines, they cannot be considered in\nbe weathered and thus less hazardous to seabirds\nisolation. Other significant mortality factors, such\nby the time it reached St. Matthew Island. However,\nas the stressful natural environment, commercial\nan accident in the vicinity of the island during the\nfishing on species that the birds prey on, deaths\nbreeding season could be disastrous. Large frac-\nof birds in fishing gear (cf., for example, Ainley\ntions of the local breeding populations could be\net al. 1981, DeGange and Newby 1982), and OCS\ndestroyed.\nactivities elsewhere in the Bering Sea region\nIn the Navarin Basin proper the available infor-\nnecessitate a more holistic concern. The combined\nmation on seabird distributions and densities\neffects of all such impacts should be assessed dur-\nduring the open-water season suggests that for\ning impact analyses.\nmost species no significant population-level effects\non seabirds would ensue in the event of a major\n9.5.3 Geographic Assessments\noil spill. Recurrent concentrations of seabirds are\nOil and gas developments in the Navarin Basin\nrestricted in time, space, or both, thereby reducing","Navarin Basin Synthesis\n132\nthe potential for exposure of large numbers of the\n160°\nbirds to the oil. Consistently high densities (>75\n64°\n170°\nbirds/km², coefficient of variation < 2.0) are assoc-\n180°\niated with the hydrographic front at the shelf break\n64°\n62°\nfrom spring through fall, as well as with the 100-m\nfront in spring (Eppley and Hunt 1984. Fig. 9.9).\n62°\n60°\nMost of the birds present in abundance are the rel-\natively vulnerable locally breeding, diving species\n60°\nrather than the nonbreeding, migrant shearwaters\n58°\nprevalent away from the Pribilof colonies in the\n50 m\nsoutheastern Bering Sea. Eppley and Hunt's obser-\n58°\n100 m\n56°\nvations suggest that large fractions of the world's\n2000 m\npopulation of some species (e.g. Aethia auklets,\n56°\n160°\nmigrant Red Phalaropes) may be concentrated in\n200 m\nthe region at times.\n180°\n170°\nThe sparse data base leaves many questions\nunanswered about spills during winter. Research\non pelagic and ice-edge seabird distributions by\nSpring\nHunt and Divoky indicates that the geographic\ncoincidence of the ice edge and the shelf break\nat times may foster large concentrations of seabirds\nthat could be impacted by oil. Further, it is\nspeculated that production platforms may create\ndownstream polynyas, attracting large numbers of\nbirds which would then be vulnerable to spills at\nthe platforms.\nThe Pribilof Islands are of special concern due\nto their large and unique seabird resources. Major\nSummer\nfractions of several world and Alaska seabird\npopulations nest there, most notably the Red-\nlegged Kittiwake. The development of a forward\noil support and transshipment port at the Pribilofs\nwould have a number of potential consequences\non the seabird colonies. They are similar in quali-\nRisk Values\nty to those described for St. Matthew Island and\nConsistently high\nhave been described in detail by Strauch and Hunt\nHigh but variable\n(1982).\nLow but variable\nConsistently low\nIt is likely that any oil produced in the Navarin\nFall\nBasin will be tankered through Unimak Pass to an\nSymbol Values\noil terminal on Morzhovoi Bay. Tanker traffic\nthrough the pass would expose large numbers of\nBirds/km2\nseabirds foraging or nesting locally as well as those\n75.1\n75\nat the nearby Fox Islands colonies. During the\nCV<2\nbreeding season nearly 2 million seabirds are at\nCV2.\nthe Fox Islands, including about 50% of the world\npopulation of Whiskered Auklets and 45% of\nAlaska's Tufted Puffins. The Unimak Pass and Fox\nIslands seabirds also are described by Strauch and\nFIGURE 9.9 -Evaluation of encounter risk for birds in\nthe Navarin Basin: spring, summer, and fall. CV indi-\nHunt (1982).\ncates coefficient of variation. (Adapted from Eppley\nIf an oil terminal is built in Morzhovoi Bay about\n1 million seabirds nesting on islands in or near the\nand Hunt 1984.)","Oil & Gas Development & Issues\n133\nPhase\nActivity\nPotential Hazard\nEffect\nKill\nInjure\nSeismic survey\nShock waves\nAffect hearing/sonar\nNo effect\nExploration\nDrilling\nAttract\nRepel\nNoise\nDisturb\nNo effect\nAir support\nSurface contact\nDeath\nIngestion\nProduction\nVessel support\nBlowout\nInhalation\nAcute\nBaleen fouling\nFood web disruption\nNo effect\nConstruction\nChronic\nSpill\nAs in Acute\nBioaccumulation\nSubtle organ damage\nTransport vessels\nNo effect\nPerturbation\nTransportation\nOnshore support\nHabitat disruption\nOnshore activity\n(pinniped rookeries,\ninshore cetaceans)\nNo effect\nPipeline emplacement\nBoat collision\nAll Phases\nDisturbance\nIntersect migratory routes\nOil leakage\nNo effect\nFIGURE 9.10-Proximate factors associated with offshore oil exploration and their effects on marine mammals.\n(Redrawn from Geraci and St. Aubin 1980.)\nentrance to the bay will be at risk from oil spills\ntwo species are attracted to oil slicks (Boersma\nduring the breeding season, as well as large num-\n1983), while the others are alcids and thus very\nbers of non-breeding birds year round. Fork-tailed\nvulnerable to oil spills.\nand Leach's Storm-petrels, Horned and Tufted\nFollowing the opening of oil terminals in the\nPuffins, and Cassin's Auklets are the numerically\nOrkney and Shetland islands, thousands of sea-\ndominant nesters there (Sowls et al. 1978). The first\nbirds killed by oil pollution were found shed","Navarin Basin Synthesis\n134\npolar bears. Loss of thermal insulation can bring\nashore in the Northern Isles of Scotland. It was\nabout hypothermia and pneumonia (cf. Costa and\nnot evident that tankers using the terminals were\nKooyman 1981; Cowles et al. 1981). (Polar bears\nresponsible for the spills, but operational controls\nalso can suffer kidney and other internal damage\non incoming tankers at Sullom Voe dramatically\nas a result of oil ingestion.) Pinniped species that\nreduced the number of oil spills and oiled birds\nrely on a subcutaneous blubber layer for insula-\n(Richardson et al. 1982). The controls included the\ntion have not evidenced acute metabolic effects\nrequirement that all incoming tankers carry at\nfollowing exposure to spilled oil; manifestations of\nleast 35% ballast, specified vessel routes, vessel\noil exposure have been of a transient, non-lethal\ninspections, regular and unscheduled air surveil-\nnature, such as eye irritation (Geraci and Smith\nlance, and \"blacklisting\" of offending tankers.\n1977). Captive ringed seals fed 5-ml doses of SH-\nbenzene- and 14C-naphthalene-labeled crude oil for\n9.6 MARINE MAMMAL ISSUES\n4 or 5 days or immersed for 24 hours in a tank\nhaving a 1-cm surface layer of oil evinced only\nGeraci and St. Aubin (1980) reviewed the exist-\nminimal overt effects (Engelhardt 1978). The ex-\ning knowledge of impacts on marine mammals\nperiments resulted in short-term accumulations of\nresulting from OCS oil and gas development. A\npetroleum hydrocarbons in the seals tissues and\ngeneralized schema of the spectrum of activities\nand potential effects that they developed is shown\nbody fluids. Effects of longer exposures are not\nknown, but may result in greater tissue accumula-\nin Figure 9.10; included are physical, physiological,\nand behavioral perturbations. More recently,\ntion, particularly in blubber.\nSimilarly, no overt health effects have been\nCowles et al. (1981) prepared a similar review\ndocumented in cetaceans after encounters with\nspecifically focused on marine mammals occur-\nspilled oil. During the 1969 Santa Barbara spill gray\nring in Alaskan waters. Due to its pertinence, the\nwhales were migrating in the vicinity, but no\nlatter document forms the basis for much of the\nsignificant increase in strandings ensued. Strand-\nfollowing discussion.\ned whales examined had no detectable crude oil\nAs evident from Figure 9.10, potential for impact\nhydrocarbons in their tissues. Questions about\nto marine mammals is present during all phases\nof OCS oil and gas development and as a conse-\nhealth effects of oil exposure on cetacean skin.\npossible blowhole fouling, and baleen fouling are\nquence of virtually every major activity. The\nstill being debated. As the outermost layer of ceta-\ndegree of impact will be a function of the exposure\nregime and the particular animal's vulnerability\ncean skin is composed of live cells, there is concern\nthat oil exposure could cause irritation. Certain\nand sensitivity. Impacts can be broadly categor-\nrecent laboratory studies of baleen fouling are\nized either as those causing direct physical harm\nor those indirectly affecting the animal. They can\nsomewhat equivocal, one (cited in U.S. Department\nbe further categorized as either episodic or chronic\nof the Interior 1983) suggesting rapid cleansing\nfollowing exposure to crude oil, the other (Braith-\nin nature. In general, it is evident that our knowl-\nwaite et al. 1983) the converse. However, in both\nedge of the effects of offshore oil and gas activities\non marine mammals is largely descriptive and\nexperiments long-term reductions in filtration\nefficiency were not appreciable. Inhalation of\nmeager as compared to many other trophic groups.\nliquid-phase oil via the blowhole or blowhole plug-\nThis is due in large part to the inherent intract-\nability of most marine mammals as experimental\nging appears possible, but unlikely, due to the\nsubjects and their complex and as yet poorly\nexplosive exhalation, rapid inhalation, and blow-\nunderstood behavioral and social repertoires.\nhole closure in the cetacean breathing cycle. Some\ngas vapors and volatile components of petroleum\n9.6.1 Oil Effects\ncould be inhaled, the health effects of which are\nImpacts on marine mammals due to large oil\nunknown.\nspills have received considerable attention.\nPotential indirect effects of oil spills on marine\nResearch to date suggests that the animals most\nmammals include reductions in the abundance of\nat risk are those vulnerable to oiling of pelage, such\nprey available to the animals. Such losses are\nas furred seals (including pups), sea otters, and\nthought to be negligible for most baleen whales","Oil & Gas Development & Issues\n135\nbecause they rely in large part on planktonic\nrookeries and haulouts, where panic stampedes of\ncrustaceans that have high recovery potentials as\nadults may result in crushed pups and repeated\nwell as being ubiquitous. Furthermore, whales are\ndisturbance may cause abandonment of young or\nhighly mobile and can seek prey outside the af-\nthe rookery (Johnson 1977).\nfected area. In contrast, a large oil spill affecting\nWaterborne sound results from OCS activities\nthe benthos could be more serious for bottom-\nsuch as geophysical seismic surveying, well drill-\nfeeding species such as gray whales, bearded seals,\ning, and vessel traffic. Of these, seismic surveying\nand walruses. Many of the prey organisms used\nis the major source of high levels of sound energy\nby those mammals have little or no mobility, more\nin the water. A description of the seismic surveying\nrestricted distributions, and relatively slow\ntechniques and procedures, the various equip-\nrepopulation capabilities.\nments employed, and the characteristics of the\nOther contaminants associated with OCS activ-\nacoustic waves produced is given in the draft sup-\nities such heavy metals are not considered to\nplemental environmental impact statement for the\nproduce more than very localized effects on\nSt. George Basin (U.S. Department of the Interior\nmarine mammals or their prey due to the limited\n1983). The draft supplemental EIS states that max-\nquantities released and their typically rapid dilu-\nimum source levels of 230-270 decibels (dB)\ntion and dispersion in the receiving waters.\nrelative to 1 micropascal (uPa) at 1 m are attained\nduring seismic surveys. These are the highest\n9.6.2 Disturbance Effects\nsound pressure levels associated with OCS oil and\nDisturbance effects on marine mammals are of\ngas activities. (By way of comparison, 10 pounds\nconcern. Most are attributed to noise associated\nof TNT generates acoustic pressures of about\nwith OCS activities. The potential range of impacts\n160-180 dB in the frequency range of 20-100 Hz\nresulting from water- or airborne sounds extends\nat a range of 100 yards [30 m] from the point of\nfrom bodily injury in extreme cases to no observ-\nexplosion [cf. Braham et al. 1982, p. 75].) The\nable physical or behavioral effect. Impact will\ngeneration of such extreme acoustic pressures has\ndepend on three factors: the source characteristics,\nraised concerns about direct physical impairment\nthe transmission medium, and the \"receiver,\" or\nof hearing of marine mammals as well as other\nanimal. The character of the sound source (energy,\nauditory effects inducing behavioral changes or\nfrequency spectrum, transmission rate, etc.) plays\nimpaired communication between animals. An in-\nan important role, as do the sound propagation\ncrease of ambient sound levels by 10 dB decreases\nproperties of the transmission media-air, water,\nby a factor of two the maximum range of signal\nand possibly ice. Probably most important in terms\ndetectability, assuming a constant signal to noise\nof perceived effect, and least known, is the\nratio at the receiver. Thus increases in waterborne\n\"receiver.\" The response of the animal will reflect\nnoise have implications with respect to long-range\nthe complex interplay of factors such as physio-\ncommunication by marine mammals, especially\nlogical state, prior habituation, individual species'\nif widely scattered individuals compose single\nsensitivities, and numerous other variables. The\nsocial units.\ngeneral poor knowledge of social behavior for\nRecent research on the responses of bowhead\ncetacean species in the Bering Sea further com-\nwhales to seismic operations in the Canadian\npounds the problem of interpretation of responses\nArctic (Fraker et al. 1982) has produced somewhat\nfor that mammal group.\nmixed results. In one series of observations signifi-\nResponses of many marine mammals are season-\ncant behavioral differences were noted at a range\nally variable, with strong reactions to disturbance\nof 5 km, and in another none occurred at 3 km.\nbeing elicited at some times and little reaction dur-\nReanalyses of some data suggest responses were\ning others. Such variation has been documented\nevoked at ranges up to 40 km. Habituation to\nfor a number of marine mammals in the Bering\nseismic noise is a possible explanation for the dif-\nSea (Burns and Harbo 1977; Cowles et al. 1981).\nfering responses. Research on gray whale reactions\nAirborne noise produced by aircraft is often impli-\nto a powerful deep-penetration seismic system con-\ncated as a disturbing agent in the case of marine\nducted off California indicated no overt responses\nmammals hauled out of the water. Such distur-\nby the migrating whales until the range to the\nbance is of particular concern in the vicinity of\nsound source was about 5 km. At distances less","136\nNavarin Basin Synthesis\nthan 1.6 km obvious behavioral changes including\nmammals in the Navarin Basin planning unit are\nconfused swimming, rolling, milling, swimming\nlargely speculative due to the paucity of substan-\ninto the surf, and swimming behind rocks were\ntive data on the effects of stressors such as seismic\nobserved (U.S. Department of the Interior 1983).\nexploration. aircraft and vessel traffic, and other\nPeak sound levels in this experiment were about\nagents. Frequent vessel and helicopter traffic can\n180 dB re 1 uPa at a distance of 0.8 km.\nbe anticipated between production sites in the\nbasin and St. Matthew Island, as well as vessel\n9.6.3 Geographic Assessments\ntraffic between the sites and southern Bering Sea\nThe Navarin Basin planning unit lies totally\nsupport bases. Whether such activity will cause\nwithin the pelagic regime of the Bering Sea. Within\ndisplacement of marine mammals or not is an\nthe planning unit the marine mammal species\nopen question. As noted earlier, there is evidence\nmost at risk appear to be fin whales, which are\nthat for some species, habituation to intruding\nrelatively abundant year-round residents, the\nactivities and noise may occur. However, this may\nbowhead and belukha whales, walruses, and rib-\nnot be true for others. In Puget Sound, harbor seal\nbon, bearded and spotted seals present during the\nhauling out, once common throughout the region,\nice season, and right whales and perhaps ribbon\nis now largely restricted to the more thinly settled\nseals during the open-water season. The portion\nareas of the sound or to the nighttime period\nof the planning unit encompassing the outer con-\n(Calambokidis et al. 1978).\nThe establishment of a forward support base and\ntinental shelf appears to have the highest impact\ntransshipment terminal at St. Matthew Island\nexposure potential as marine mammal densities\nare greatest there throughout the year and this\nwould produce interactions of a potentially\nportion of the planning unit also contains the pro-\nadverse nature for local marine mammal popula-\nspective sedimentary basins that are likely to be\ntions. Oil spills during the winter-spring period\ncould affect bowhead and belukha whales over-\nthe focus of OCS activities. Other physical factors\nalso come into play. For example, the position of\nwintering in the polynya near the island as well\nthe ice edge in the planning unit will vary from\nas other ice-associated mammals in the vicinity.\nyear to year, depending upon prevailing climatic\nAn oil.spill during the open-water season might\nconditions. This too will affect distributions of\nimpact summering walruses, spotted seals, Steller\nmarine mammals during that period. Due to the\nsea lions, and gray whales present in the area.\npaucity of information on marine mammal\nActivities at a St. Matthew industrial complex-\ndistributions in the region it is not possible at this\nespecially noise-producing aircraft landings and\njuncture to provide better geographical resolution\ntakeoffs-may lead to decreased use or abandon-\nas to concentration areas in the planning unit.\nment of haulouts by pinnipeds. Such adverse\nMajor oil spills during the production phase in\neffects would appear to be most likely at the\nthe Navarin Basin are likely to be infrequent based\nsoutheastern end of the island where development\non past operational histories in similar areas, such\nis expected to occur. Walrus, spotted seals, and\nas the North Sea. Thus the potential for adverse\nSteller sea lions currently use haulouts in the area.\neffects on marine mammals from large spills is\nSpilled oil and disturbance are also possible\nperceived to be low. Small spillages are much more\nalong tanker routes from the Navarin Basin region\nlikely. If offshore loading of petroleum eventuates,\nto the proposed transshipment facility on the\nthere will be a higher probability of such spills in\n'southern side of the Alaska Peninsula or, if a\nthe planning area than in the case of a find result-\npipeline to St. George Island is constructed, along\ning in the piping of oil to St. Matthew Island or\nthat pipeline route, at the St. George terminal, and\nthe Pribilof Islands. As in the case of large spills,\nbetween the St. George terminal and the southern\nchronic small volume releases of oil should not.\nAlaska Peninsula terminal. The potential impacts\nadversely affect marine mammals due to the rela-\nof such events are comparable to those that may\ntively small number of potential spill sources within\noccur in the event of OCS oil and gas development\na large area, the small volumes released and the\nin the St. George Basin or in the North Aleutian\nrapid dispersion and dilution anticipated in the\nShelf planning areas. These have been described\nin detail in Hameedi (1982) and Thorsteinson\nhigh energy ocean environment.\nAssessments of disturbance impacts on marine\n(1984). The reader is directed to those documents","Oil & Gas Development & Issues\n-\n137\nfor further information.\nof spills involving releases of over 1,000 bbl of oil\nA final comment: Many marine mammals mi-\nmight range from about two to nine, while spillages\ngrate extensively. As a consequence, mammals\nof over 10,000 bbl might range from roughly one\nusing the Navarin Basin may also be exposed to\nto four over the expected 15- to 25-year lifetime\nimpacts in other OCS oil and gas leasing areas both\nof the Navarin Basin activity. (Offshore loading\nwithin and outside Alaska. The gray whale is a\nspillage rates were assumed to be equivalent to\nnotable example. During its seasonal migrations\nthose of tankers in port.) The assumptions about\nbetween wintering and summering areas the spe-\nthe shuttle tankers likely to be employed suggest\ncies traverses numerous OCS areas in California\nthat the largest potential tanker spill would be\nand Alaska, thus markedly increasing its exposure\nabout 1 million bbl of oil.\npotential both in space and time. Little has yet\nModeling, opportunistic research on oil spills,\nbeen done to assess such cumulative effects.\nand laboratory experimentation have provided a\nbasis for assessing the transport and environmental\n9.7 SUMMARY AND CONCLUSIONS\npartitioning of petroleum in the sea, and its fate\nunder a variety of circumstances. It is anticipated\nAs described in Section 9.1, the level and\nthat during open-water conditions in the Navarin\ncharacter of activity in the Navarin Basin and\nBasin spilled oil would be carried approximately\nother areas of the Bering Sea associated with a\nnortheastward at some 10-15 km/d. Evaporation\ncommercial oil and gas discovery in the basin will\nwould be the major process rapidly removing the\nbe largely determined by the size and geograph-\npetroleum from the sea surface; perhaps 40% of\nical disposition of the producing fields. Within the\nthe oil might be removed by evaporation within\nNavarin Basin proper the number of production\na few days. Given the high wave and mixing\nplatforms might range from 6 to 18. Subsea pipe-\nenergy prevalent in the region, it is expected that\nlines may be required, depending on the size of\nrapid dispersal and weathering of the oil would\nthe field; they could transport oil to St. Matthew\noccur and that water-in-oil emulsions would quick-\nIsland, or to the Pribilofs in the event of a large\nly develop. The emulsions would form streamers\nfind. One or two ice-strengthened shuttle tankers\nor slicklets within the main slick area and then\nwould be required to transfer oil from the Navarin\neventually break up into tarballs and, ultimately,\nfield facilities to a transshipment port in the Alaska\nsmall particles. Dissolution and sedimentation\nPeninsula area. It also is assumed that a forward\nwould remove oil from the sea surface, but would\nsupport facility would be developed on St. Mat-\nbe processes of lesser magnitude than evaporation\nthew Island; the facility probably would include\nduring the period immediately following the spill.\na large airfield, harbor, oil storage, and treatment\nThe amount of oil entering the water column would\ncapabilities. About 4,000 acres of land, or about\ndepend strongly on the prevailing mixing energy,\n5% of the island's area, might be available for use\nwhile the significance of sedimentation would be\nfor the facility.\nA major issue central to the proposed OCS oil\nand gas development in the Navarin Basin is the\npotential for major oil spills and their environmen-\nTABLE 9.15-Summary of occurrence rates for acciden-\ntal oil spills currently used in the MMS oil spill trajec-\ntal consequences. Operational data from other\ntory analysis model.\nOCS areas demonstrate that such oil spills are rare\nevents, being roughly proportional to the volume\nNumber of Spills/Billion bbl Oil Handled\nof oil handled. Lanfear and Amstutz (1983) have\nSource\n1,000 bbl\nreported some recent statistics on oil spills from\n10,000 bbl\nvarious sources. They are tabulated in Table 9.15.\nPlatforms\n1.0\n0.44\nActual spill rates in the Navarin Basin likely will\nPipelines\n1.6\n0.67\ndiffer from those given here due to differences in\nTankers:\noperating conditions and technology employed.\nTotal\n1.3\n0.65\nBased upon the foregoing spill statistics and the\nAt sea\n0.9\n0.50\nmaximum and minimum resource levels employed\nIn port\n0.4\n0.15\nin the development scenarios, the likely number\nSOURCE: Lanfear and Amstutz 1983.","Navarin Basin Synthesis\n138\nat Prudhoe Bay. It is anticipated that. in the event\ndetermined by the availability of suitable sus-\nof offshore loading or the development of a trans-\npended particulate matter substrates in the vicinity\nshipment terminal at St. Matthew Island, ballast\nof the spill. Photo-oxidation and microbial degrada-\nwater from tankers would be treated to remove\ntion would be insignificant in the short term.\nresidual oil before being discharged into the sea.\nThe fate of oil spilled in ice-infested waters such\nIn short, chronic operational releases from produc-\nas occur in the Navarin Basin much of the year\ntion platforms or terminals are not anticipated to\nis more problematic given the large variety of such\ncause more than very localized environmental\nspill circumstances that are possible and the\nstress in the Navarin Basin region.\nrelative lack of information about the outcomes\nIn terms of their relevance to OCS oil and gas\nof such events. During the ice season, trajectory\ndevelopment, the dominant environmental haz-\nmodels indicate dominantly southwesterly move-\nards in the Navarin Basin region appear to be\nment of oil at speeds of 10-15 km/d; however,\nwinds and waves, superstructure icing, and sea ice.\nreversals of direction might be expected when\nThese regional hazards are thought to pose more\natmospheric lows pass through the region. In\ndifficulties for the operational aspects of develop-\ngeneral, within the pack ice it can be expected that\nment than they are for the engineering design\nthe processes acting to remove oil from the sea\naspects (W. Spring pers. commun.). In comparison\nsurface would be less effective due to the lower\nto the southern Bering Sea and Gulf of Alaska,\nenergy available to promote them. Oil slicks also\ngeological hazards in the Navarin Basin region ap-\nwould be expected to spread less due to contain-\npear relatively innocuous. Formidable engineer-\nment by ice floes. Significant amounts of oil may\ning challenges to be encountered in the Navarin\nbe sequestered on, within, or under the ice to be\nBasin oil and gas development include the design\nreleased at times and locations far removed from\nof deep-water production platforms adequate to\nthe spill event.\nwithstand large lateral wave and ice forces, the\nThe most frequent spillages of petroleum are\nconstruction of an artificial harbor at St. Matthew\nsmall ones. These, combined with possible routine\nIsland, which has no natural harbors, and the con-\ndischarges of formation waters, drilling fluids and\nstruction of a support base on the island proper.\ncuttings, ballast water, and other operational\nDevelopment of an oil transshipment terminal on\ndischarges comprise potentially chronic sources\nthe Alaska Peninsula will require careful site selec-\nof contamination in the vicinity of producing oil\ntion and structural design to withstand a likely\nfields and support facilities. The environmental\ngreat earthquake and associated ground shaking,\neffects of such operational discharges are reviewed\ntsunamis, and seiches. Experience gained during\nin Read and Blackman (1980), Davies et al. (1981),\nthe development of offshore fields in the Arctic,\nDicks and Hartley (1982), Menzie (1982), and Sharp\nCook Inlet, Canadian east coast. and North Sea will\nand Appan (1982). A general conclusion reached\nmaterially aid in the development of facilities\nby the reviewers is that widespread severe con-\nsuitable to withstand the rigorous environmental\ntamination due to operational discharges has not\nstresses in the Navarin Basin and Alaska Penin-\nyet been observed in producing offshore oil fields.\nsula areas. A notable exception to this generaliza-\nIn the British North Sea fields, for example, signifi-\ntion concerns offshore loading of oil. That activity\ncant hydrocarbon contamination has been found\nhas not yet been attempted in ice-infested waters.\nonly in sediments close to platforms where oil-\nThe potential impacts of OCS oil and gas devel-\nbased drilling muds have been dumped (Davies et\nopment in the Navarin Basin on the regional biota\nal. 1981). It is unlikely that over-the-side releases\nare a major issue. Key groups include marine\nof untreated oil-based muds would be allowed in\nmammals (especially endangered whales), marine\nAlaskan OCS fields. The general National Pollutant\nbirds, and fishes and shellfishes of commercial im-\nDischarge Elimination System (NPDES) permits be-\nportance. Other organisms also are of some-albeit\ning developed by the EPA for various Alaskan\nlesser-concern due to their roles as prey of the\nregions prohibit the discharge of oil-based muds\nkey groups and functional components of regional\nduring exploration activities. Further, other produc-\ntion platform releases probably would be minimal;\necosystems.\nIt appears that a large oil spill in the vicinity of\nformation waters may be reinjected to maximize\nSt. Matthew Island during summer could cause\nrecovery of oil from the producing formations, as","Oil & Gas Development & Issues\n139\nsignificant population-level mortalities of breeding\nof most cetacean species in the region. A large oil\nfulmars, murres, and Crested and Least Auklets.\nspill in the vicinity of the marginal ice zone dur-\nThis high exposure potential results from the fact\ning spring might produce locally high mortalities\nthat in contrast to regions such as the Gulf of\nof seals, but losses that are significant at the\nAlaska and British Isles, where breeding colonies\npopulation level do not appear possible from such\nare smaller, more numerous, and dispersed, most\nan event.\nBering Sea seabirds breed at a few megacolonies\nThe impacts of spilled oil on commercial fish\n(G. Hunt pers. commun.). Within the Navarin Basin\nstocks in the Navarin Basin would be mediated\nproper oil spills likely would not produce signifi-\nlargely through mortalities of larvae at or near the\ncant population reductions because of the rela-\nsea surface. Consideration of such a scenario dur-\ntively low pelagic densities of the birds and the\ning the Navarin Basin synthesis meeting produced\nconsequent small percentage of populations likely\nthe conclusion that oil-induced reductions of fish\nto encounter the oil.\npopulations would not be distinguishable from the\nThe longer-term population responses of sea-\nlarger fluctuations produced by natural mortality\nbirds to oil-induced mortalities are debatable due\nfactors and fishing operative in the region.\nto the incompleteness of the information necessary\nInferences about the potential impacts of spilled\nto assess the issue. Chronic low-level mortalities\noil on populations of lower trophic-level organisms\nof certain age groups of the populations of some\nin the Navarin Basin are best made via observa-\nspecies may produce adverse long-term population\ntions from other localities or laboratory findings\nlevel effects as, for example, has been predicted\ndue to the paucity of supportive data from the\nfor the murre colonies at the Pribilof Islands by\nbasin. No significant effects would be expected for\nthe Wiens et al. (1979) model. Conversely, British\nspecies resident in the water column. Davenport\nseabird populations appear to be increasing in spite\n(1982) notes that pelagic oil spills are typically\nof incremental mortalities induced by OCS oil and\nfollowed by rises in bacterial and yeast numbers,\ngas operations in the North Sea and oily water\ntemporary falls in zooplankton densities, and\ndischarges by vessels at sea (Dunnet 1982). Bourne\nincreases in phytoplankton production. In the case\n(1982) contends that oil pollution at sea is in the\nof the Amoco Cadiz spill, he states that no differ-\nlong term only reinforcing the effects of natural\nences in zooplankton composition (including fish\nmortality processes usually operating at a much\nlarvae) were detectable between affected and\nlarger scale, which seabird populations are spe-\ncontrol areas about 1 month after the event.\ncifically adapted to counteract through relaxation\nObservable differences in the benthos appear\nof density-dependent limitations on population\nmore likely (but still of low probability) if petroleum\ngrowth. There appears to be potential to address\nhydrocarbons accumulate at the sea floor. Such a\nthe question of such longer-term impacts indirectly\nsituation would be possible in the Navarin Basin\nthrough research on the impact of high seas gillnet\nregion only in very localized areas, as at a major\nmortalities (over 250,000/year) of seabirds in the\noil spill site or in the immediate vicinity of a\nNorth Pacific and Bering Sea (Ainley et al. 1981)\nchronic source of pollutants. In the British North\non breeding populations in the Aleutian Islands.\nSea fields the highest sediment oil concentration\nContrary to the situation for marine birds, a\nrecorded thus far was 257 ug/g total oil about 0.8\nmajor oil spill near St. Matthew Island during\nkm from a platform where oil-based drilling muds\nwinter appears to have the most potential for\nwere being used (McIntyre 1982). Griffiths et al.\nadversely affecting marine mammal populations.\n(1982) demonstrated long-term (18 months) in situ\nAs noted in Chapter 8, the polynya that develops\neffects on microbial processes in sediments amend-\nin the vicinity of the island during the ice season\ned with crude oil. Nitrogen fixation rates were\nappears to be an important overwintering habitat\nsignificantly reduced at fresh oil concentrations of\nfor a large portion of the endangered bowhead\n1 ppt, the lowest concentration employed and\nwhale population as well as for a number of other\nroughly four times the highest value observed in\nmarine mammal species. Within the Navarin Basin\nthe North Sea fields.\nplanning unit proper. exposure potential appears\nThe impacts of oil on benthic invertebrate\nminimal, as suggested by the extremely low occur-\nspecies will depend on the oil's bioavailability and\nrence rates of large oil spills and the low densities\nthe organisms sensitivity to the oil. Community","Navarin Busin Synthesis\n140\nexception of a few overt examples (e.g., chick and\nresponses will involve interactions between species\negg losses at seabird cliffs. pup abandonment at\nas well. The Amoco Cadiz event produced widely\nrookeries), it is not generally possible to show\nvarying responses to oil among the affected benth-\ncausality between the impacting agent and a\nos. An Abra alba-Melinna palmata community in\ndeleterious effect observed in an individual, much\nan eutrophic muddy sand environment of Morlaix\nless a population. Rather, most organismic distur-\nBay displayed considerable immediate mortalities\nbance impacts are more subtle; they are thought\nof some species followed by a proliferation of op-\nto result in increased stress, abandonment of tradi-\nportunist species and a continuation of a normal\ntional use areas, impairment of social interactions,\nlife cycle by others. Elsewhere in the bay an Abra\nor numerous other possibilities.\nalba-Hyalinoecia bilineata fine sand community\nThe complex and controversial issue of distur-\ndisplayed initial mortalities but little change in\nbance impacts on marine birds and mammals due\ncommunity structure (Dauvin 1982). Two species\nto oil and gas activities in the Alaskan OCS has\nof Ampelisca were completely destroyed in the bay\nthus far been addressed through imposition of\n(Conan 1982).\nregulations and advisory stipulations intended to\nGeneralizations arising from observations such\nprevent or mitigate possibly harmful interactions.\nas the foregoing are that the impacts of oil on\nIn the case of endangered species, the primary\nbenthos are greater and longer lasting in low-\nvehicle has been regulation, while for non-\nenergy, depositional environments, presumably\nendangered species it has been stipulations. Distur-\ndue at least in part to the longer persistence of\nbance impacts in the Navarin Basin likely will be\noil and a preponderance of detrital feeding organ-\ntreated similarly.\nisms (which increases the bioavailability of the oil).\nThe greatest potential for disturbance impacts\nCommunity level changes and recovery times will\nto marine birds and mammals appears to be at St.\ndepend upon the interplay of a variety of chemical,\nMatthew Island, where development of a support\nbehavioral, and ecological factors (Vandermeulen\nfacility will result in a high level of year-round ac-\n1982). Although presumably sensitive detrital-\ntivity. Included would be the construction of the\nfeeding benthic communities appear to predom-\nfacility itself and its operation, which probably\ninate in the Navarin Basin, they do not seem to\nwould involve frequent vessel movements, heli-\nbe very vulnerable on a population basis due to\ncopter flights, and in the event of a medium or\nthe anticipated restricted distributions of petroleum\nlarge commercial find, jet aircraft traffic. Seasonal\nhydrocarbons on the sea floor at concentrations\nconcentrations of nesting birds and hauled out\nhigh enough to be harmful.\nmammals at either end of the island as well as\nIntertidal habitat is very limited in the Navarin\noverwintering bowhead whales in the vicinity are\nBasin region, the closest being present at St.\nthe primary groups likely to be affected. Protec-\nMatthew and its neighboring islands. Inasmuch as\ntive measures should be directed toward them.\nthe intertidal zone there appears to be strongly\nImpacts of industrial development on St. Mat-\nphysically dominated, resident biota would be ex-\nthew Island could be considerable. This island, part\npected to be opportunistic and adapted to frequent\nof the Bering Sea National Wildlife Refuge, cur-\ndisturbance. Species diversity likely is low, as.\nrently is uninhabited by man. If a support base\nobserved by O'Clair (1981) at the Pribilof Islands.\neventuates, the wilderness character of the south-\nFor the presumably comparable intertidal situation\neastern portion of the island will be degraded to\nat the Pribilof Islands, O'Clair concluded that the\nsome degree. Endemic biota such as the McKay's\nnet effect of an oil spill would be a reduction in\nBunting may suffer declines if exotic organisms\nspecies richness and a prolonged period of return\nto a natural community. Local extinctions of\ngain a foothold.\nMarked visual impacts and physical disturbance\nspecies such as those utilizing refuges from ice\nwill result from jetport construction. Large quan-\nscouring (e.g., boulder interstices, cracks in rocks)\ntities of rock will have to be quarried to construct\nwould be possible as they would be vulnerable to\nbreakwaters required to provide sheltered dock-\nthe oil.\ning for rig support vessels and tankers. These and\nThe potential disturbance effects on marine birds\nother construction activities will require sensitive\nand mammals associated with oil and gas activities\nand careful planning in order to minimize the im-\nwere described in Sections 9.5 and 9.6. With the","Oil & Gas Development & Issues\n141\npacts occurring during operation of the facility, as\nbe small if the scenario assumptions hold true. In\nwell as promoting reversion to natural status when\nthe Gulf of Mexico, which has some 7,600 offshore\noil production ceases and the facility is dismantled.\nwells, the area loss amounts to a few thousandths\nDirect interference of OCS oil and gas activities\nof 1% of the total grounds, while in the North Sea\nwith commercial fisheries in the Navarin Basin ap-\nfields the grounds lost are 0.3-1% (McIntyre 1982).\npears probable given the geographic coincidence\nExperiences in other offshore fields indicate that\nof the fishing grounds and potential petroleum pro-\nfouling or damage of fishing gear by oil-related\nducing basins. The degree of interference should\ndebris is probably the greatest source of conflict\nbe minimal, however. The trawlable ground lost\nbetween the industries. Such problems appear\nto production platforms and other structures will\namenable to solution by regulatory mechanisms.","","References Cited\nAINLEY, D. G., A. R. DEGANGE, L. L. JONES, AND R.\nAUDUNSON, T.\nJ. BEACH.\n1978. The fate and weathering of surface oil from the\n1981. Mortality of seabirds in high-seas salmon gill\nBravo blowout. In C. C. Bates (ed.), The pro-\nnets. U.S. Natl. Mar. Fish. Serv. Fish. Bull. 79(4):\nceedings of the conference on assessment of\n800-806.\necological impacts of oil spills, 14-17 June 1978,\nAINLEY, D. G., AND G. A. SANGER.\nKeystone, Colorado, p. 445-475. Am. Inst. Biol.\n1979. Trophic relations of seabirds in the Northeastern\nSci., Washington, D.C.\nPacific Ocean and Bering Sea. In J. C. Bartonek\nBAKKALA, R. G., AND G. B. SMITH.\nand D. N. Nettleship (eds.), Conservation of\n1978. Demersal fish resources of the eastern Bering\nmarine birds of northern North America, p.\nSea: spring 1976, vol. 1. Processed rep., 234 p. U.S.\n95-122. U.S. Fish Wildl. Serv. Res. Rep. 11.\nDep. Commer., NOAA, Natl. Mar. Fish. Serv.,\nALEXANDER, V., AND T. CHAPMAN.\nNorthwest and Alaska Fish. Cent., 2725 Montlake\n1981. 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Alaska\nMarilyn Allen\nLee Gefvert\nJerry Imm\nArctic Environmental Information\nARCO\nMinerals Management Service\nand Data Center\nAnchorage, Alaska\nAnchorage, Alaska\nAnchorage, Alaska\nJoy Geiselman\nBradley Ingram\nKevin Banks\nCentaur Associates, Inc.\nMinerals Management Service\nMinerals Management Service\nWashington, D.C.\nAnchorage, Alaska\nAnchorage, Alaska\nHans Jahns\nKaren Gibson\nBill Benjey\nExxon Production Research Co.\nMinerals Management Service\nMinerals Management Service\nHouston, Texas\nAnchorage, Alaska\nAnchorage, Alaska\nLaurie Jarvela\nJudy Gottlieb\nMarsha Bennett\nNOAA, National Ocean Service\nMinerals Management Service\nMinerals Management Service\nJuneau, Alaska\nAnchorage, Alaska\nAnchorage, Alaska\nBen Jarvi\nStephen Grabacki\nReed Bohne\nMinerals Management Service\nDames & Moore\nOffice of Coastal Zone Management\nAnchorage, Alaska\nAnchorage, Alaska\nWashington. D.C.\nToni Johnson\nChristopher Bowden\nDavid Hale\nMinerals Management Service\nAlaska Department of Fish & Game\nMinerals Management Service\nAnchorage, Alaska\nAnchorage. Alaska\nAnchorage, Alaska\nHerman Karl\nThomas Boyd\nJawed Hameedi\nU.S. Geological Survey\nMinerals Management Service\nNOAA, National Ocean Service\nMenlo Park, Calif.\nAnchorage. Alaska\nJuneau, Alaska\nDale Kenney\nJohn Brueggeman\nPeter Hanley\nMinerals Management Service\nEnvirosphere\nSohio\nAnchorage, Alaska\nSeattle, Wash.\nAnchorage, Alaska\nBruce Kirstein\nDee Chamberlin\nScience Applications. Inc.\nDon Hansen\nARCO\nLa Jolla, Calif.\nMinerals Management Service\nLos Angeles, Calif.\nAnchorage, Alaska\nGunner Knapp\nDrew Comer\nInstitute of Social and Economic\nJack Heesch\nMinerals Management Service\nResearch\nMinerals Management Service\nAnchorage, Alaska\nAnchorage, Alaska\nAnchorage, Alaska\nChuck Cortese\nThomas Kozo\nNancy Hendrix\nLouis Berger Associates. Inc.\nTetra Tech\nMinerals Management Service\nDenver. Colo.\nPasadena, Calif.\nAnchorage, Alaska\nCleve Cowles\nJoseph Kravitz\nSharon Hillman\nMinerals Management Service\nNOAA, National Ocean Service\nSohio\nAnchorage, Alaska\nWashington, D.C.\nAnchorage, Alaska\nPaul Dubsky\nStephen Leatherwood\nMinerals Management Service\nJoel Hubbard\nHubbs-Sea World\nAnchorage Alaska\nMinerals Management Service\nSan Diego, Calif.\nAnchorage, Alaska\nGordon Euler\nJan Leendertse*\nMinerals Management Service\nWilliam Hunnicut\nRand Corporation\nAnchorage. Alaska\nARCO\nSanta Monica, Calif.\nMark Fraker\nGeorge Hunt\nDavid Liu\nSohio\nUniversity of California\nRand Corporation\nAnchorage Alaska\nIrvine. Calif.\nSanta Monica. Calif.\n157","99802"]}