Brook trout movement during and after recolonization of a naturally defaunated stream reach
Abstract
In june 1995 a debris flow associated with a massive streamwide flood completely eliminated brook trout Salvelinus fontinalis from the lower 1.9 km of the Staunton River in Shenandoah National Park, Virginia. Biannual diver counts revealed that brook trout moved several hundred meters into the debris-flow-affected area each year, resulting in complete recolonization within 3 years of the event. We initiated a postrecolonization, biannual mark-recapture survey in 1997 and a radiotelemetry sudy in 1999 to further examine the movement of brrok trout within the Stauton River. Fish that moved less than 100 m upstream or downstream made up 91% of brook trout recaptures; them aximum movement was over 800 m . Telemetered fish showed median seasonal movements of less than 70 m but a maximum movement of nearly 2 km. Despine the limitations in inherent in movement studies, we observed postrecolonization movements consistent with those that were the basis for recolonization of the defaunted reach. Understanding the ability of movement to effect population changes is necessary for proper management in the wake of catastrophic events.