1. U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit; 5755 Nutting Hall, Orono ME 04469-5755 U.S.A.
2. Department of Wildlife Ecology; University of Maine; Orono ME 04469 U.S.A.
3. School of Marine Sciences; University of Maine; Orono ME 04469 U.S.A.
4. U.S. Fish and Wildlife Service, Abernathy Fish Technology Center; 1440 Abernathy Creek Road Longview WA 98632 U.S.A.