Monitoring Demographic and Genetic Responses of a Threatened Inland Trout to Habitat Reconnection

AbstractFreshwater fishes living in streams and rivers can be affected strongly by isolation, which causes a disproportionate degree of fragmentation in such dendritic systems. Isolation disrupts important ecological and migratory processes as well as the ability to access refuge habitats during disturbances. The restoration of habitat connectivity, then, should be a productive strategy for improving the resiliency of freshwater fish populations, but the local and broader ecological benefits of barrier removal are still poorly understood. We report on a long-term, spatially intensive effort to monitor the responses of inland trout to stream habitat reconnection at a watershed scale, using both demographic and genetic techniques. Individual-based genetic assignment uncovered clear evidence of movement into the primary tributary of interest, which had been blocked by an assumedly complete barrier, but the source population generating this movement varied over time. A linear mixed-effect model suggested trou...