Genetic Analyses Provide Insight into the Early Ocean Stock Distribution and Survival of Juvenile Coho Salmon off the Coasts of Washington and Oregon

Abstract Estimating the stock proportions of mixed-stock fishery samples by means of genetic stock identification has played an important role in the management of salmon fisheries. In addition, stock identification of individual fish has applications for population studies, forensic cases, and management issues. We examined 11 microsatellite DNA loci in 84 populations of coho salmon Oncorhynchus kisutch sampled at 78 locations from southern British Columbia to northern California to construct a database of microsatellite allele frequencies. We then evaluated the applicability of the database for estimating stock proportions in a mixed fishery and assigning individuals to their regions of origin. The loci were highly polymorphic: observed heterozygosity ranged from 0.754 to 0.943. Using genetic distance calculations, we identified six major geographic regions and 15 smaller subregions into which the populations grouped. Computer simulations and a sample of 143 coho salmon with known origins showed that th...