Allozymes and Mitochondrial DNA Discriminate Asian and North American Populations of Chum Salmon in Mixed-Stock Fisheries along the South Coast of the Alaska Peninsula

Abstract

A representative baseline of allozyme allele frequencies of 69 stock groupings covering the entire range of chum salmon Oncorhynchus keta was evaluated for its ability to estimate stock of origin of Asian and North American chum salmon in complex mixtures. We estimated the origin of 2,000 chum salmon harvested incidentally in fisheries for sockeye salmon O. nerka along the south side of the Alaska Peninsula in the northern Pacific Ocean in 1993 and 1994 using a maximum likelihood algorithm. Of eight major regions (Japan, Russia, northwest Alaska summer run, Yukon River fall run, Alaska Peninsula–Kodiak Island, southeast Alaska, British Columbia, and Washington) reported, northwest Alaska summer-run populations predominated in the fishery with estimates ranging from 0.52 to 0.72. A mitochondrial DNA (mtDNA) marker capable of distinguishing the Japanese component from the rest of the Pacific Rim stocks was assayed in 400 of the 1994 samples. Estimates from the allozyme and mtDNA data were similar. Monitoring of the fishery and expansion of the chum salmon baseline are continuing.