Microsatellite DNA variation and estimation of stock composition of sockeye salmon, Oncorhynchus nerka, in Barkley Sound, British Columbia

Microsatellite DNA variation at six microsatellite loci (Omy77, Ots3, Ots10 0, Ots103, Ots107, and Ots108) was examined in approximately 900 sockeye sa lmon, Oncorhynchus nerka, collected between 1987 and 1995 from three stocks an the west coast of Vancouver Island, British Columbia, Canada. Variation in allele frequencies among stocks was, on average, about 12 times greater than temporal variation within stocks. Individual locus F-ST estimates ran ged from 0.013 to 0.107 among stocks, with an overall value of 0.056. Analy sis of simulated mixed-stock samples indicated that data from four to six o f the microsatellite loci surveyed would enable relatively accurate and pre cise estimates of stock composition for mixtures composed of fish from the three stocks. Application of the mixture analysis to 1100 fish sampled in B arkley Sound and Alberni Inlet fisheries during 1997 indicated that sockeye salmon from Great Central Lake constituted about 70% of the commercial cat ch. The later time of return of sockeye salmon from Henderson Lake than of those from Great Central or Sproat Lake as previously indicated by analysis of parasite frequencies was confirmed in the 1997 fishery sampling. Stock composition of catches varied among gears, presumably owing to gear selecti vity.