|Document Type:||Journal Article|
|Title:||Genetic analyses provide insight into the early ocean stock distribution and survival of juvenile coho salmon off the coasts of Washington and Oregon|
|Author:||Donald M. Van Doornik, David J. Teel, David R. Kuligowski, C. A. Morgan, Edmundo Casillas|
|Journal:||North American Journal of Fisheries Management|
Estimating the stock proportions of mixed-stock fishery samples by means of genetic stock identification (GSI) 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 coho salmon populations from 78 locations to construct a database of microsatellite allele frequencies for populations from southern British Columbia to northern California. We then evaluated the applicability of using the database to estimate stock proportions in a mixed fishery, and to identify individuals to their region of origin. The loci were highly polymorphic - observed heterozygosities ranged from 0.7540.943. Using genetic distance calculations, we identified 6 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 the database was sufficient to make accurate stock proportion estimates to the 15 subregions. For the sample of fish with known origins, individual assignments to region of origin were 82.5% accurate for all samples, and 97.8% accurate for those where P > 0.95. We used the database to estimate stock proportions and densities of 2,344 coho salmon sampled over eight summers in a juvenile salmon marine ecology study conducted off the coasts of Washington and Oregon. Columbia River juveniles were caught at higher densities than coastal fish throughout the summer. Fish from Columbia River and coastal sources were captured both north and south of their point of sea entry in early summer, and at higher densities than in late summer. September catches of Columbia River juveniles were correlated with adult abundances the following year, indicating that year class strength for this stock is largely set during their first summer in the ocean.