Genetic analyses to establish captive breeding priorities for endangered snake river sockeye salmon

The plight of the Snake River sockeye salmon presents a challenging genetic puzzle for conservation biologists. Although the Snake River sockeye has been declared endangered, assessment of captive breeding strategies are complicated because a healthy non-migratory strain of O. nerka (kokanee) resides in Redfish Lake, Idaho-the same lake the anadromous fish return to for spawning. The migration of 1-year-old fish (outmigrants) from the lake each year and the observation of non-migratory fish spawning in areas previously used by the sockeye further complicate the issue. We estimated the relatedness of these strains by direct examination of their genetic similarity. Mixed DNA fingerprint analyses suggested that the outmigrants were more closely related to the anadromous sockeye than to the kokane. Closer analysis using a probe, One-H0.8, to examine allele frequencies at a single locus revealed polymorphism in a number of O. necka populations. Within the Redfish Lake populations this probe detected an allele present at 0.21 frequency in the kokanee (n = 43), 0.01 (n = 324) in the outmigrants, and absent among 13 anadromous fish. These results support a close genetic relationship of the outmigrants to the anadromous sockeye and the probable utility of the outmigrants in a captive breeding program to restore the anadromous strain.