Genetic impacts of put-and-grow brook trout stocking on tributary populations of Virginia impoundments

The state of Virginia maintains a put-and-grow stocking program for brook trout (Salvelinus fontinalis) to provide trophy fishing opportunities in several small, low-order stream impoundments.  The tributaries of these reservoirs often contain putative native populations of brook trout as well.  The degree to which trout stocked in the reservoir colonize the tributaries, spawn in these tributaries, and potentially influence the genetic structure of native populations is unknown.  We used microsatellite data to compare population genetics among tributaries of three stocked impoundments and two hatchery strains.  One of the tributaries did not contain brook trout historically, allowing us to easily assess the degree of tributary colonization by fish stocked in the reservoir.  Our data indicate, not surprisingly, that stocked trout extensively colonized tributaries and spawned within them.  However, we found little evidence for interbreeding among putative native and hatchery-origin stocks.  These results are discussed in the context of conservation genetics of brook trout and balancing objectives of stocking and restoration programs.