Size, Age, and Migration of Yellow-Phase American Eels in the Potomac River Drainage, Mid-Atlantic Region, USA

Studies on the ecology of American eels in the mid-Atlantic Region, USA, include a recent management emphasis on dam passage during upstream migration. Size, age, and upstream migration of American eels were examined at an eel ladder, Millville Dam, Shenandoah River, from 2003 to 2011. About 15,000 eels were counted at the Millville Dam eel ladder since 2003. Eels using the ladder ranged primarily from 200 to 550 mm in length, and 3 to 10 years in age. Upstream movements of eels during spring, summer, and fall were associated with an increase in river flow and darker nights on or near the new moon. Monitoring of the eel ladder at Millville Dam will continue, with plans for additional ladders at dams farther upstream allowing a more comprehensive study on eel movements within the Shenandoah River watershed.