Genetic contribution of three introduced life history forms of sockeye salmon to colonization of Frazer Lake, Alaska

Colonization of Frazer Lake (Kodiak Island, Alaska) by sockeye salmon (Onco rhynchus nerka) represents a rare, successful introduction of this species into a new environment. Eggs, fry, and adults were introduced repeatedly in to Frazer Lake from 1951 to 1971. Donors originated from three source popul ations, each with different life histories: late-run lake shoreline spawner s (Karluk Lake), early-run inlet tributary spawners (Red Lake), and late-ru n lake outlet spawners (Ruth Lake). We used six nuclear DNA (nDNA) microsat ellite loci and mitochondrial DNA (mtDNA) to determine which donor populati on(s) had colonized the principal spawning habitats of Frazer Lake: three s horeline areas and four inlet tributaries. Based on nDNA comparisons, two s horeline-spawning populations were most similar to the shoreline donor, and the four tributary-spawning populations were most similar to the tributary donor. However, five of the seven Frazer Lake populations appeared to be i nfluenced genetically by more than one donor. Genetic distances based on mt DNA were independent of life histories with high (relative to nDNA) interpo pulation variation, suggesting significant female founder effects and posts tocking drift. Our data suggest that life history adaptations of donor popu lations were critically important for successful colonization of Frazer Lak e, thus underscoring the need to consider life history traits in other intr oduction and recovery programs.