Microsatellite Stock Identification of Chum Salmon on a Pacific Rim Basis

The variation at 14 microsatellite loci was analyzed for more than 53,000 chum salmon Oncorhynchus keta from 381 locations ranging from Korea to Washington State and used to estimate the stock composition of mixed-stock fishery samples. High resolution of the samples was possible, the number of reporting groups being distributed as follows: Korea = 1, Japan = 7, Russia = 8, Alaska = 15, Canadian Yukon River = 5, British Columbia = 16, and Washington State = 5. The number of alleles observed at a locus was related to the power of the locus in providing accurate estimates of the stock composition of single population mixtures. Approximately 800 alleles were observed across the 14 microsatellites, providing the basis for high-resolution stock identification. Analysis of known-origin samples indicated that accurate regional estimates of stock composition were obtained. The estimated stock compositions of mixed-fishery samples from coastal Japan, the Sea of Okhotsk, the western Pacific Ocean, the Gulf of Alaska, and coastal British Columbia were quite different among samples and clearly reflected the presence of local populations. Microsatellites have provided the ability to obtain accurate estimates of the stock composition of chum salmon from many locations in the Pacific Rim.