Exploiting genetic diversity to balance conservation and harvest of migratory salmon

Population-based management is central to the conservation of highly exploited species. Managing to sustain population diversity is especially challenging for migratory species. The aggregate of populations of sockeye salmon (Oncorhynchus nerka) that spawn in drainages of Bristol Bay, Alaska, is the most abundant in the world and supports the largest high-value salmon fishery in North America. We applied molecular tools (genetic data from 38 single nucleotide polymorphisms, assayed in 96 populations) to detect migratory trends in stock composition of sockeye salmon returning to Bristol Bay and to inform fisheries management in real time. We reliably and repeatedly detected abundances that were unanticipated based upon preseason forecasts, fishing effort was shifted accordingly, and the fleet and local economies benefited while the risk of overharvesting weaker stocks was minimized. This approach is being developed for other species and fisheries and provides a useful model for conservation wherever migrating species are intensely managed.