Predicting Naturally Produced Oregon Coast Adult Coho Salmon (Oncorhynchus kisutch) Survival from Multiple Jack Return Datasets

Returns of precocious males (jacks) and other sibling relationships have been used to predict abundance and survival for multiple salmon species and stocks. Until recently hatchery coho salmon jack/smolt ratios, predominantly from the Columbia River, were used as a component of fisheries management for naturally produced Oregon coast coho salmon. Since 1998 we have trapped and counted all returning coho salmon jacks and estimated smolt out-migrants at a small coastal Oregon tributary, providing a very precise but spatially limited jack metric. We also visually counted jacks in an average of 479 randomly selected coastal stream segments, providing an imprecise but representative jack metric. The Columbia River hatchery jack predictor remains useful for Columbia River hatchery adults, but both coastal jack indicators outperformed the Columbia River hatchery jack predictor, with the spatially limited but precise trap counts having the strongest relationship to the coastal marine survival index. Both coastal jack indicators are now used in coastal coho fisheries management. These results suggest there are differences in marine survival between coho salmon from different areas and origins and underscore the need for stock specific predictors.