A genetic analysis of samples from the chum salmon (Oncorhynchus keta) 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 11 microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2010, genetic samples were collected as part of the species composition analysis of the Alaska Fisheries Science Centers North Pacific Observer Program. This sampling change for 2010 was an interim measure implemented until the systematic sampling protocols are finalized. Consequently, stock composition estimates apply to the sample set and may not represent the entire chum salmon bycatch. Based on the analysis of 1,048 chum salmon bycatch samples collected throughout the 2010 Bering Sea trawl fishery, East Asian (38%), North Asian (26%), Western Alaska (14%), and Eastern Gulf of Alaska/Pacific Northwest (13%) stocks dominated the sample set, with smaller contributions from Upper/Middle Yukon River (7%) stocks. The estimates for the 2010 chum salmon bycatch sample set were similar to the 20052009 chum salmon bycatch estimates, suggesting consistency of the regional stock contributions across years. Analysis of temporal groupings within the groundfish B season revealed changes in stock composition during the course of the season with decreasing contribution of Western Alaska and Eastern Gulf of Alaska/Pacific Northwest stocks and increasing contribution of North Asian stocks over time, but leaves unanswered whether these changes are due to temporal or spatial differences in the sample set.

A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2011 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for 11 microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2011, genetic samples were collected systematically as part of a special project to reduce sample biases that exist in collections from previous years that have the potential to affect stock composition analysis results. One genetic sample was collected for every 31.1 chum salmon caught in 97% of the midwater trawl fishery that was sampled. Evaluation of sampling based on time, location, and vessel indicated that the genetic samples were representative of the total bycatch. Based on the analysis of 1,472 chum salmon bycatch samples collected throughout the 2011 Bering Sea trawl fishery, the Eastern Gulf of Alaska (GOA)/Pacific Northwest (PNW) stocks dominated the sample set (38%), with moderate contributions from East Asian (17%), North Asian (18%), and Western Alaska (16%) stocks, and smaller contributions from Upper/Middle Yukon River (9%) stocks. The estimates for the 2011 chum salmon bycatch sample set differed from the 20052010 estimates, indicating a change in the consistency of the regional stock contributions across the previous 6 years, possibly due to the larger proportion of bycatch caught later in the season and in the more southeastern NMFS reporting areas in 2011. There were significant spatial differences in stock distribution, with the Asian stocks dominating the central Bering Sea area and the Eastern GOA/PNW stocks dominating the southeastern Bering Sea. Analysis of temporal groupings revealed changes in stock composition during the course of the season with decreasing contribution of East Asia and Upper/Middle Yukon stocks and increasing contribution of Eastern GOA/PNW stocks over time.

A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2007 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for eleven microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2007, genetic samples were collected opportunistically as part of a special project, but sample biases have the potential to affect stock composition analysis results. Consequently, stock composition estimates apply to the sample set and may not represent the entire chum salmon bycatch. Based on the analysis of 1,279 chum salmon bycatch samples collected throughout the 2007 Bering Sea trawl fishery, North Asian (35%), East Asian (34%), and Eastern Gulf of Alaska/Pacific Northwest (16%) stocks dominated the sample set, with smaller contributions from Western Alaska (10%) and Upper/Middle Yukon River (5%) stocks. The estimates for the 2007 chum salmon bycatch sample set were similar to the 2005, 2006, and 2009 chum salmon bycatch estimates, suggesting consistency of the regional stock contributions across years. Analysis of temporal groupings within the groundfish B season revealed changes in stock composition during the course of the season with decreasing contribution of Upper/Middle Yukon stocks over time, but leaves unanswered whether these changes are due to temporal or spatial differences in the sample set.

A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2006 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for eleven microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2006, genetic samples were collected opportunistically as part of a special project, but sample biases have the potential to affect stock composition analysis results. Consequently, stock composition estimates apply to the sample set and may not represent the entire chum salmon bycatch. Based on the analysis of 1,367 chum salmon bycatch samples collected throughout the 2006 Bering Sea trawl fishery, North Asian (31%), East Asian (29%), and Pacific Northwest (25%) stocks dominated the sample set with smaller contributions from Western Alaska (8%) and Upper/Middle Yukon River (6%) stocks. The estimates for the 2006 chum salmon bycatch sample set were similar to the 2005 and 2009 chum salmon bycatch estimates, suggesting consistency of the regional stock contributions across years. Analysis of temporal groupings within the groundfish B season revealed changes in stock composition during the course of the season with decreasing contribution of Upper/Middle Yukon stocks over time, but leaves unanswered whether these changes are due to temporal or spatial differences in the sample set.

A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2012 Bering Sea walleye pollock (Gadus chalcogrammus) trawl fishery was undertaken to determine the overall stock composition of the sample set. A genetic analysis of chum salmon collected during a test of a salmon excluder device was also conducted. Samples were genotyped for 11 microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2012, genetic samples were collected systematically as part of a special project that commenced in 2011 to reduce sample biases that exist in collections from previous years and have the potential to affect stock composition analysis results. One genetic sample was collected for every 31.5 chum salmon caught in the 98% of the midwater trawl fishery that was sampled. Evaluation of sampling based on time, location, and vessel indicated that the genetic samples were representative of the total bycatch. Based on the analysis of 673 chum salmon bycatch samples collected throughout the 2012 Bering Sea trawl fishery, the North Asian stocks dominated the sample set (39%), with moderate contributions from East Asian (20%), Eastern Gulf of Alaska (GOA)/Pacific Northwest (PNW) (18%), and Western Alaska (14%) stocks, and smaller contributions from Upper/Middle Yukon River (7%) and Southwest Alaska (2%) stocks. The estimates for the 2012 chum salmon bycatch sample set differed from the mean of the 20052011 estimates for the two Asian regions, but not for the North American regions. The pattern of changes of regional stock contributions over three time periods in 2012 differed from previous years for some regions. There were some spatial differences in stock distribution; e.g., the East Asian stock contribution was higher in the central Bering Sea than in the southeastern Bering Sea. As with the bycatch samples, the salmon excluder device test samples included fish from all geographic regions despite being collected at small spatial and temporal scales.

A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2005 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for eleven microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2005, genetic samples were collected opportunistically as part of a special project and supplemented with archived scales from the Observer Program. Sample biases have the potential to affect stock composition analysis results; consequently, stock composition estimates apply to the sample set and may not represent the entire chum salmon bycatch. Based on the analysis of 1,084 chum salmon bycatch samples collected throughout the 2005 Bering Sea trawl fishery, East Asian (29%), North Asian (29%), Pacific Northwest (19%) and Western Alaska (16%) stocks dominated the sample set with smaller contributions from Southwest Alaska (<2%) and the Upper/Middle Yukon River (5%) stocks. The estimates for the 2005 chum salmon bycatch sample set were similar to the 1994-1995 chum salmon bycatch estimates, suggesting consistency of the regional stock contributions across years. Analysis of temporal groupings within the groundfish B season revealed changes in stock composition during the course of the season. Whether the decreasing proportional contributions of Western Alaska and Upper/Middle Yukon stocks and increasing proportional contributions from Asia over time are due to temporal or spatial differences in the sample set are unknown.

A genetic analyses of samples from the Chinook salmon (Oncorhynchus tshawytscha) bycatch from the 2007-2013 Bering Sea-Aleutian Island and Gulf of Alaska trawl fisheries for walleye pollock (Gadus chalcogrammus) were 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 some years, the Bering Sea trawl fishery incidentally harvests (bycatch) large numbers of chum salmon. Because chum salmon were declining in some western Alaska areas, the origins of the chum salmon bycatch were important. Tagging studies have shown that chum salmon originating in Asia and North America migrate through the eastern Bering Sea. Genetic stock identification (GSI), a method of estimating stock composition in mixed-stock fisheries, has helped in evaluating stock contributions to salmon fisheries on the western coast of North America. Through cooperative efforts between state and federal agencies, a comprehensive genetic baseline for Pacific Rim chum salmon stocks has been developed, which enables GSI in fisheries such as the Bering Sea trawl fishery. In 1994, the National Marine Fisheries Service, Auke Bay Laboratory, initiated a feasibility study of GSI in determining the origins of the chum salmon bycatch in the Bering Sea trawl fishery. Sampling in 1995 was intensified and resulted in samples covering the entire fishing season, representing nearly 11% of the total chum salmon bycatch. Estimates for our 1994 fishery samples over three period were 39-55% Asian stocks, 20-35% western Alaska stocks, and 21-29% southeastern Alaska, British Columbia, or Washington stocks. One small sample (N=47) of maturing fish showed a surprisingly large contribution of British Columbia stocks (53%). Estimates for our 1995 samples over seven time periods were 13-51% Asian stocks, 33-53% western Alaska stocks, and 9-46% southeastern Alaska, British Columbia, or Washington stocks. As in 1994, the sample of maturing fish (N=277) showed a large contribution of British Columbia stocks (49%) and Washington stocks (25%).

Genetic data of salmon bycatch samples collected by fisheries observers are used for mixed-stock analyses to determine geographic region of origin. This work is done at the Auk Bay Lab in Juneau Alaska. The data are loaded to the the North Pacific Halibut and Groundfish database maintained by FMA Division at the Alaska Fisheries Science Center in Seattle Washington

Chum salmon populations from across their geographic distribution have been analyzed with a set of SNP and microsatellite markers. As is typical for chum salmon populations, more genetic divergence was observed on larger geographic scales than on smaller regional scales. Strong divergence exists within and among the three regions of Asia, western Alaska, and the northeast Pacific. However, separation of coastal western Alaskan summer-run chum salmon populations, from Norton Sound to northern Bristol Bay remains problematic. The degree of divergence determines the spatial scale to which stock proportions of mixtures of chum salmon can be resolved. The baseline developed in this project will be used for mixture analyses to study the marine distribution of chum salmon populations in the Bering Sea. Scale and fin samples collected in the eastern Bering Sea will be used to determine whether the stock composition of chum salmon aggregations differ across areas, seasonally, and annually. Determining the stock distributions of these mixtures will provide information on the migratory pathways of chum salmon in the Bering Sea and the potential impact of bycatch of coastal western Alaskan chum salmon in the Bering Sea pollock fishery.