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.