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Allocating observer sea days to bottom trawl and gillnet fisheries in the northeast and Mid-Atlantic regions to monitor and estimate incidental bycatch of marine mammals
  • Published Date:
    2007
Filetype[PDF - 501.91 KB]


Details:
  • Personal Authors:
  • Corporate Authors:
    Northeast Fisheries Science Center (U.S.)
  • Series:
    Northeast Fisheries Science Center reference document ; 07-19
  • Document Type:
  • Description:
    "Estimating marine mammal bycatch mortality with low levels of uncertainty is important in attaining the conservation goals of the Marine Mammal Protection Act. The Protected Species Branch at the Northeast Fisheries Science Center allocates fishery observer sea days to achieve a 30% precision on estimates of incidental marine mammal bycatch in US gillnet and bottom trawl fisheries conducted off the Atlantic coast of the United States. A three-step process is used to: (1) project sample sizes; (2) proportionally allocate projected sea days to fishery strata; and (3) assign allocated sea days to ports and months within strata proportional to fishing effort. Under conditions of limited observer funding, a set of decision rules is followed to establish which fisheries will receive observer coverage. The amount of observer coverage (in sea days) needed to achieve a 30% precision in the bycatch estimates varies widely among fishery strata. In the 2007 fiscal year (October 2006 - September 2007), funding was only available for 802 observer sea days, although nearly 57,000 sea days are required provide a 30% precision in the bycatch estimates of harbor porpoise (Phocoena phocoena) and bottlenose dolphin (Tursiops truncatus) in the Northeast and Mid-Atlantic gillnet fisheries, and for pilot whales (Globicephala spp.), white-sided dolphin (Lagenorhynchus acutus), and common dolphin (Delphinus delphis) in the Northeast and Mid-Atlantic bottom trawl fisheries. After the decision rules were applied in FY07, all 802 observer sea days were allocated to coverage of the gillnet fisheries; 47% (377 days) was allotted to the Northeast gillnet fishery and 53% (425 days) to the Mid-Atlantic gillnet fishery. Due to the very large amount of fishing effort in the Northeast and Mid-Atlantic bottom trawl fisheries, a substantial increase in annual sampling coverage is required for monitoring what are essentially rare marine mammal bycatch events in these fisheries"--Abstract.