Population Genetics and the Management of Arctic-Yukon-Kuskokwim Salmon Populations
Fred M. Utter, Megan V. McPhee, and Fred W. Allendorf
Abstract.—The genetic population structures of chum Oncorhynchus keta, Chinook O. tshawytscha, coho O. kisutch, sockeye O. nerka, and pink O. gorbuscha salmon within the AYK region are described based on available published and unpublished information. The most detailed genetic data were for chum salmon where major groups included: (1) summer-run fish returning to coastal rivers and the lower reaches of the Yukon and Kuskokwim Rivers, (2) upper Yukon River, and (3) upper Kuskokwim River fall-run populations. AYK Chinook and coho salmon populations showed similar patterns of differentiation within the Yukon and Kuskokwim Rivers, although each species had quite different spatial separation and timing. Based on unpublished genetic data from AYK sockeye salmon populations, Norton Sound populations were grouped together and were distinct from ten other areas within the Yukon and Kuskokwim drainages which had affinities with Bristol Bay populations. Available pink salmon data were insufficient to estimate population structures. Similarity of AYK and Susitna River chum and Chinook salmon populations suggest a common ancestry that may reflect an historical connection of these drainages. Low species-wide indices of among-population genetic variation (FST) in chum and pink salmon suggest that regionally based conservation strategies for these species will be effective. In contrast, Chinook, coho, and sockeye salmon had higher FST values and require population-specific strategies. Genetic stock identification methods (mixed stock analysis) provided valuable estimates of oceanic distributions of AYK chum salmon, and in-season estimates of chum, Chinook, and coho salmon stocks migrating within the Yukon and Kuskokwim Rivers. The genetic information now known about salmon in the AYK region will help the formulation and design of future investigations, and will ultimately promote a better understanding, management, and conservation of AYK salmon.