Genetic stock composition analysis of the Chinook salmon bycatch from the 2014 Bering Sea walleye pollock (Gadus chalcogrammus) trawl fishery

A genetic analysis of samples from the Chinook salmon (Oncorhynchus tshawytscha) bycatch of the 2014 Bering Sea-Aleutian Island (BSAI) trawl fishery for walleye pollock (Gadus chalcogrammus) was undertaken to determine the overall stock composition of the bycatch. Samples were genotyped for 43 single nucleotide polymorphism (SNP) DNA markers and results were estimated using the Alaska Department of Fish and Game (ADF&G) SNP baseline. In 2014, genetic samples from the Bering Sea were collected using a systematic random sampling protocol where one out of every 10 Chinook salmon encountered was sampled. Based on the analysis of 1,385 Chinook salmon bycatch samples collected throughout the 2014 BSAI walleye pollock trawl fishery, Coastal Western Alaska stocks dominated the sample set (49%) with smaller contributions from North Alaska Peninsula (18%), British Columbia (14%), and West Coast U.S. (WA/OR/CA) (7%) stocks. Analysis of temporal groupings within the pollock "A" and "B" seasons revealed changes in stock composition during the course of the year with lower contributions of Coastal Western Alaska, North Alaska Peninsula and Yukon stocks and higher contributions of West Coast U.S. (WA/OR/CA), British Columbia, NW Gulf of Alaska and Coastal Southeast Alaska stocks during the "B" season.