Applied Genetics Inform the Management and Conservation of Endangered Coho Salmon (Oncorhynchus kisutch) in Central California

Coho salmon (Oncorhynchus kisutch) of central California are in decline and ESA-listed as endangered. The species is now absent from many formerly occupied streams and remaining populations are generally small, inbred and lack diversity. Two captive broodstock programs operate in this area, in an effort to conserve and recover the species. Warm Springs Hatchery on the Russian River and Kingfisher Flat Hatchery on Scott Creek support recovery to the north and the south of the Golden Gate, respectively. Both programs utilize multiple molecular genetic-based strategies to meet their goals, including 1) use of spawning matrices to avoid inbreeding and maximize diversity, and 2) managed outbreeding to incorporate out-of-basin diversity into the native but inbred captive broodstocks. In addition, both programs provide fish for juvenile and adult stream-releases. Release of mature adults directly into spawning habitat is a relatively novel approach for reintroduction and supplementation of coho salmon and we use genetic data to examine the outcomes of these releases. Parentage analyses for several spawning seasons demonstrate that these captive-bred adults readily spawn in streams and that there is higher survival of outbred than non-outbred juveniles. This diversified approach plays a crucial role in the recovery of these critically endangered fishes.