Craig Roghair

Response of a Brook Trout Population and Instream Habitat to a Catastrophic Flood and Debris Flow

Abstract In June 1995, a massive flood and debris flow impacted fish and habitat along the lower 1.9 km of the Staunton River, a headwater stream located in Shenandoah National Park, Virginia. In the area affected by debris flow, the stream bed was scoured and new substrate materials were deposited, trees were removed from a 30-m-wide band in the riparian area, and all fish were eliminated. In the area that was unaffected by debris flow, habitat was moderately altered by the flood and fish populations persisted at decreased densities. Basinwide fish population and habitat surveys provided data to compare (1) the pre- and postevent population densities of brook trout Salvelinus fontinalis and instream habitat conditions and (2) postevent population density, brook trout growth, and instream habitat in the debris-flow-affected and unaffected areas. By June 1998, brook trout had recolonized the entire debris-flow-affected area, and population density exceeded preevent levels. Brook trout growth was significan...

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 study in 1999 to further examine the movement of brook trout within the Staunton River. Fish that moved less than 100 m upstream or downstream made up 91% of brook trout recaptures; the maximum movement was over 800 m. Telemetered fish showed median seasonal movements of less than 70 m but a maximum movement of nearly 2 km. Despite the limitations inherent in movement studies, we observed postrecolonization movements consistent with those that were the basis for recolonization of the defaunated reach. Understandi...