Genetic stock composition analysis of Chinook salmon bycatch samples from the 2010 Bering Sea trawl fisheries
Abstract
A genetic analysis of samples from the Chinook salmon (Oncorhynchus tshawytscha) bycatch of the 2010 Bering Sea groundfish trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for 43 single nucleotide polymorphism DNA markers and results were estimated using the Alaska Department of Fish and Game (ADF&G) SNP baseline. In 2010, genetic samples were collected as part of the observer's species-composition analysis. This sampling change for 2010 was an interim measure implemented until recommended systematic sampling protocols could be finalized. Consequently, stock composition estimates apply to the sample set and may not represent the entire Chinook salmon bycatch. Based on the analysis of 826 Chinook salmon bycatch samples collected throughout the 2010 Bering Sea trawl fishery, Coastal Western Alaska stocks dominated the sample set (42%), with smaller contributions from Upper Yukon River (20%), North Alaska Peninsula (14%) and Middle Yukon River (11%) stocks. The annual estimates for the 2010 Chinook salmon bycatch sample set were generally similar to the 2005–2009 Chinook salmon bycatch estimates, although there were higher proportions of Yukon River stocks and lower proportions of Coastal Western Alaska stocks in 2010. Analysis of temporal groupings within the groundfish "A" and "B" seasons revealed changes in stock composition during the course of the year with lower contribution of North Alaska Peninsula and Yukon River stocks and higher concentrations of Pacific Northwest and British Columbia stocks during the "B" season, but leaves unanswered whether these changes are due to temporal or spatial differences in the sample set.
