Monitoring Reproductive Success of Sockeye Salmon Reintroduced into Cle Elum Lake from Two Distinct Upper Columbia River Donor Stocks

In the early 1900’s, sockeye salmon were extirpated from Cle Elum Lake in the Yakima River Basin.  Beginning in 2009 The Confederated Tribes and Bands of the Yakama Nation initiated a reintroduction program using donor stocks originating from Osoyoos Lakes and Wenatchee Lake. The long-term goal of Cle Elum Lake reintroduction is to establish a viable, local sockeye salmon population. However, owing to differences in natal habitats and life histories of the donor stocks, the adaptive potentials of co-occurring immigrants in a novel environment was unknown. Genetic monitoring to evaluate reproductive success of transplanted fish and their progeny began in 2011. The highly differentiated donor stocks allow confident genetic assignment, revealing that Osoyoos Lakes sockeye represent the larger proportion of Cle Elum Lake outplants. Analysis of carcasses has revealed a spatial segregation of stocks between upstream and near shore environments. No significant hybridization has been observed among outmigrating smolts, although both stocks appear productive. The first naturally spawned progeny from reintroduction efforts returned as adults in 2013, and included both parental types. Continued monitoring will clarify apparent spawning distinctions between reintroduced donor stocksk in Cle Elum lake, and will be help gauge long-term relative reproductive success during the course of reintroduction.