Population structure of sockeye salmon from Russia determined with microsatellite DNA variation

The population structure of sockeye salmon Oncorhynchus nerka from Russia was determined from a survey of the variation of 14 microsatellite loci among approximately 3,750 sockeye salmon from 56 populations. The populations from Avacha Bay and the Palana River were quite distinct. Genetic differentiation among the populations surveyed was observed, the mean value of the differentiation index (F-ST) for all loci being 0.038 (SD = 0.007). Regional structuring of the populations surveyed was observed, multiple populations sampled within a lake being more similar to each other than to populations in other lakes or rivers. River drainage of origin was a significant unit of population structure. Populations spawning in rivers without access to a nursery lake for juvenile rearing displayed greater genetic variation than did populations with access to nursery lakes. Within Kurilskoye Lake, genetic differentation was observed between populations spawning in tributaries to the lake and those populations spawning along beaches within the lake. In the Kamchatka River drainage, genetic differentiation between the Azabachie Lake populations and other populations within the drainage was sufficient to discriminate between natal and nonnatal juveniles rearing in Azabachie Lake.