Genetic diversity of sockeye salmon of Cook Inlet, Alaska, and itsapplication to management of populations affected by the Exxon Valdez oilspill

摘要

Genetic data from sockeye salmon Oncorhynchus nerka were collected from all major systems in upper Cook Inlet, Alaska, that produce sockeye salmon, including the Kenai River drainage, a major system that was affected by the Exxon Valdez oil spill. The products of 29 enzymes encoded by 67 protein-encoding loci resolved by allozyme analysis revealed a substantial amount of genetic diversity among populations distributed both within and among major drainages. The data support a model of population structure based on the nursery lake. A gene diversity analysis estimated that 0.4% of the total variability was attributable to the effect of sampling at different sites within nursery lakes, compared with 7.5% among nursery lakes within regions and 2.9% among regions. This diversity probably arises from isolation and genetic drift within nursery lakes and the tendency of sockeye salmon to home with great fidelity. Sockeye salmon from these drainages are commercially harvested in mixed-stock aggregations in upper Cook Inlet. Mixed-stock analyses using maximum likelihood methods with data from 27 loci were performed to estimate the proportion of source populations in upper Cook Inlet fisheries. Simulations indicated that six regional groups (Kenai River, Susitna and Yentna rivers, West Cook Inlet, Kasilof River, Northeast Cook Inlet, and Knik Arm) could be identified in mixtures at a level of precision and accuracy useful for fishery management. Samples from fisheries were analyzed both in-season (within 48 h) and postseason. Samples taken from within the rivers were also analyzed to evaluate the baseline and to estimate the contributions of individual spawning populations to the larger river systems.