1. Environmental Quality Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 10300 Baltimore Avenue, Beltsville, Maryland 20705; National Invasive Species Council, 1951 Constitution Avenue, Suite 320, South Interior Building, Washington, D.C. 20240; and Catfish Genetics Research, Agricultural Research Service, U.S. Department of Agriculture, Experiment Station Road, P.O. Box 38, Stoneville, Mississippi 38776-0038