Genetic stock composition analysis of chum salmon from the prohibited species catch of the 2021 Bering Sea walleye pollock trawl fishery

We analyzed genetic stock compositions of chum salmon (Oncorhynchus keta) prohibited species catch (PSC), referred to as “bycatch”, samples collected from the 2021 walleye pollock (Gadus chalcogrammus) trawl fishery in the Bering Sea. Samples were genotyped for 84 single nucleotide polymorphism markers from which stock contributions were estimated using a range-wide chum salmon baseline developed by the Alaska Department of Fish and Game. The chum salmon bycatch was 546,043 fish, the second highest bycatch number since 1991 and considerably higher than the 10-year average of 257,023.