1. Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, 867 Lakeshore Road, Burlington, Ontario, Canada L0R 2H2
2. Cornell Biological Field Station, Department of Natural Resources, Cornell University, Bridgeport, New York 13030
3. Department of Zoology, Erindale College, University of Toronto, Mississauga, Ontario, Canada L5L 1C6