| Annual Survey of Juvenile Salmon, Ecologically-Related Species, and Biophysical Factors in the Marine Waters of Southeastern Alaska, May–August 2016 - :18271 | National Marine Fisheries Service (NMFS)
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Annual Survey of Juvenile Salmon, Ecologically-Related Species, and Biophysical Factors in the Marine Waters of Southeastern Alaska, May–August 2016
  • Published Date:
    2018
Filetype[PDF-1.57 MB]


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    Juvenile Pacific salmon (Oncorhynchus spp.), ecologically-related species, and associated biophysical data were collected from the marine waters of the northern region of southeastern Alaska (SEAK) in 2016. This annual survey, conducted by the Southeast Coastal Monitoring (SECM) project, marks 20 consecutive years of systematically monitoring how juvenile salmon utilize marine ecosystems during a period of climate change. The survey was implemented to identify the relationships between year-class strength of juvenile salmon and biophysical parameters that influence their habitat use, marine growth, prey fields, predation, and stock interactions. Up to 13 stations were sampled monthly in epipelagic waters from May to August (total of 23 sampling days). Fish, zooplankton, surface water samples, and physical profile data were collected during daylight at each station using a surface rope trawl, bongo nets, a water sampler, and a conductivity-temperature-depth profiler. Surface (3-m) temperatures and salinities ranged from approximately 9 to 16 ºC and 16 to 32 PSU across inshore, strait, and coastal habitats for the four months. Integrated (top 20-m) temperatures and salinities ranged from approximately 8 to 15 ºC and 24 to 31 PSU, notably the warmest 20-m integrated temperatures recorded by the SECM project. A total of 72,073 fish and squid, representing 27 taxa, were captured in 89 rope trawl hauls fished from June to August. Juvenile salmon comprised approximately 49% of the catch. For all months and habitats, juvenile pink (O. gorbuscha), chum (O. keta), sockeye (O. nerka), and coho (O. kisutch) salmon occurred in 58- 87% of the hauls, while juvenile Chinook salmon (O. tshawytscha) occurred in about 18% of the hauls. Abundance of juvenile salmon was high in 2016; peak CPUE occurred in June strait and coastal habitats. Coded-wire tags were recovered from 28 juvenile coho, that primarily originated from hatchery and wild stocks in SEAK sampled in the strait habitat; an additional 17 adiposeclipped juvenile coho and Chinook salmon without tags were present. The only non-Alaskan stocks were juvenile coho salmon recovered off Icy Point, one from the Solduc River, WA and the other from the Methow River, Washington. Of the juvenile salmon examined for otolith marks, Alaska enhanced stocks comprised 69% of the juvenile chum (503 of 726) and 18% of the juvenile sockeye salmon (107 of 489). Of the 96 potential predators of juvenile salmon, predation on juvenile salmon was observed in three of eight fish species examined. The long term seasonal time series of SECM juvenile salmon stock assessment and biophysical data is used in conjunction with basin-scale ecosystem metrics to annually forecast pink salmon harvest in SEAK. Long term seasonal monitoring of key stocks of juvenile salmon and associated ecologically-related species, including fish predators and prey, permits researchers to understand how growth, abundance, and interactions affect year-class strength of salmon in marine ecosystems during a period of rapid climate change.

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