Coho salmon colonization in recently deglaciated streams in Glacier Bay, Alaska: implications for Pacific salmon restoration

Processes associated with the evolution of ecological communities or metapopulation complexes are seldom documented from initial colonization events. Combining molecular genetic and geomorphological data, stream colonization events were examined for coho salmon (Oncorhynchus kisutch) breeding in recently deglaciated streams (50-230 yrs BP) in Glacier Bay National Park, Alaska. Population estimates of genetic diversity, coancestry and evidence of reproductive founder events were significantly related to stream age. Genetic relationships among populations correlated significantly with location and stream age suggesting a step-wise colonization process from oldest to youngest stream systems. Knowledge gained of ecological processes of natural colonization, and how genetic and demographic characteristics of newly founded or repatriated populations change over time in response to successional changes in stream habitat have significant implications for restoration and conservation of declining or extirpated salmon populations in degraded habitats across their native range.