AFSC/ABL: 2011 Chum Salmon Bycatch Sample Analysis Bering Sea

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.

This dataset contains the data from genetic analyses of fish captured in 2011 in the Bering Sea.

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For scientific, management, and regulation compliance purposes, all data collected by observers are confidential under the Magnuson-Stevens Fishery Conservation and Management Act [bm1]; as amended, Public Law 109-479; 16 U.S.C. 1953; implemented at 50 CFR 679.50. Therefore unprocessed (raw) data can be shared only with authorized persons; however aggregated forms of the data are generally available.

User must read and fully comprehend the metadata prior to use. Data should not be used beyond the limits of the source scale. Acknowledgement of NOAA, as the source from which these data were obtained, in any publications and/or other representations of these data is suggested. The user must adhere to restrictions placed on publication of data by the Magnuson-Stevens Fishery Conservation and Management Act. The user is responsible for the results of any application of this data for other than its intended purpose.

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Genotypes were scored by two people with the software GeneMapper 4.0. Samples missing genotypes from four or more loci, or having six or more homozygous loci were removed.

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