1. U.S. Geological Survey, Georgia Cooperative Fish and Wildlife Research Unit, Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia 30602;
2. U.S. Geological Survey, Great Lakes Science Center - Lake Erie Biological Station, Huron, Ohio 44839;
3. U.S. Fish and Wildlife Service, Alpena Fish and Wildlife Conservation Office, Trenton, Michigan 4818;
4. Michigan Department of Natural Resources, Lansing, Michigan 48933;
5. Quantitative Fisheries Center, Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan 48824