Genetic Stock Composition Of The Commercial Harvest Of Sockeye Salmon In Kodiak Management Area 2014 2016 PDF Download

Precise, accurate estimates of stock-specific harvests of sockeye salmon (Oncorhynchus nerka) are lacking for commercial fisheries in the Kodiak Management Area (KMA. Such information would be useful for reconstructing runs, building accurate brood tables to define escapement goals, and refining management by identifying spatial and temporal harvest patterns of local and non-local stocks. Hence, the department developed a genetic baseline for mixed-stock analysis (MSA) to estimate the stock compositions of sockeye salmon harvests in select KMA commercial salmon fisheries from 2014-2016. This report describes the methodology used to build a baseline, examines costs and benefits of a reduced marker set, describes the performance of the baseline for MSA, and provides guidance on how to interpret biases documented in the MSA tests when evaluating future stock composition estimates of KMA fishery mixtures. This genetic baseline uses single nucleotide polymorphism (SNP) markers and builds on the Western Alaska Salmon Stock Identification Project (WASSIP) sockeye salmon baseline to include additional populations in KMA and extends coverage south from Cape Suckling, Alaska to the Columbia River, Washington. The final baseline contains 65,332 individuals from 762 collections representing 473 populations in 15 reporting groups. Mean population sample size was 138 individuals. We used 2 types of tests to measure the baseline’s ability to correctly allocate to reporting groups: 100% proof tests and fishery scenario tests. Correct allocations for 100% proof tests averaged 98.2%, ranged from 80.4% to 99.6%, and 73 of the 75 proof tests met our goal of 90% correct allocation. Fishery scenario tests did not indicate any consistent directional biases among reporting groups, but misallocation was observed between Frazer and Ayakulik. Reducing the baseline from 96 to 48 SNPs had negligible effects on MSA estimates. This baseline will provide accurate and precise estimates of stock composition in KMA sockeye salmon fisheries.