1. Missouri Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife Sciences; University of Missouri; Columbia MO 65211 U.S.A.
2. Department of Wildlife, Fisheries and Aquaculture; Mississippi State University, PO Box 9690; Mississippi State MS 39762 U.S.A.
3. U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife Sciences; University of Missouri; Columbia MO 65211 U.S.A.