Genetic analysis of four wild chum salmon<Emphasis Type="Italic">Oncorhynchus keta</Emphasis> populations in China based on microsatellite markers

Synopsis To assess the genetic variation and population structure of wild chum salmon in China, we analyzed microsatellite loci for populations in the Amur, Wusuli, Suifen Current and the Tumen rivers. We evaluated expected heterozygosity with two estimators of genetic differentiation (F_ST and G_ST) and Nei’s standard genetic distance. The average expected heterozygosity across the 10 loci was 0.65 in the Wusuli River and the Suifen Current River, 0.64 in the Amur River and 0.66 in the Tumen River, The results of this study show that the recent declines in chum salmon have not led to low levels of genetic variability in China. The proportion of inter-population subdivision among chum salmon was between 5.7 and 6.8%. According to the estimator used, the NJ tree based on Nei’s standard genetic distance indicated that there were two different branches (the Sea of Okhotsk branch and the Sea of Japan branch), the Amur River and the Wusuli River populations were closer, while the Suifen Current River and the Tumen River clustered together. The genetic test for population bottlenecks provided no evidence for a significant genetic signature of population decline, which is consistent with the record of the four populations we have in the last few years.