Genetic identification of wild and domesticated strains of chinook salmon (Oncorhynchus tshawytscha) in southern British Columbia, Canada

Chinook salmon (Oncorhynchus tshawytscha) are the predominant indigenous salmonid reared in marine aquaculture in British Columbia (BC), Canada. As such, domesticated chinook strains may represent the greatest potential source of genetic interaction between wild and domesticated salmon in BC rivers. This survey of eight domesticated strains (combined N = 1100) at 13 microsatellite loci confirmed the close relationship of the domesticated strains to east coast Vancouver Island wild populations from which they were derived five to seven generations earlier, but revealed that domesticated strains possess significantly less allelic diversity than their wild progenitors and other wild chinook salmon populations throughout the species range. Maximum-likelihood analysis of simulated mixtures of wild and domesticated chinook salmon and Bayesian classification of individual domesticated chinook salmon indicated that sufficient genetic differentiation exists to enable highly accurate identification of both wild and domesticated chinook salmon to type over the species range from Russia to California. Moreover, the domesticated strains tended to be distinct from each other (average pairwise FST = 0.05, range 0.01–0.07), enabling accurate classification (> 90%) of domesticated fish to strain of origin. These results indicate that genetic methods can be used to identify escaped domesticated chinook salmon in BC and perhaps to monitor the success of their reproductive activity.