1. Institute of Nature and Environmental Technology Kanazawa University Kanazawa 920‐1192 Japan
2. Graduate School of Fisheries Sciences Hokkaido University Hakodate 041‐8611 Japan
3. Department of Natural Resources and Environmental Sciences University of Illinois Urbana Illinois61801
4. School of Aquatic and Fishery Sciences University of Washington Seattle Washington98195
5. Pacific Biological Station Fisheries and Oceans Canada Nanaimo British Columbia V9T 6N7 Canada
6. Center for Toki and Ecological Restoration Niigata University Niigata 950‐2181 Japan
7. Center for Environmental Biology and Ecosystem Studies National Institute for Environmental Studies Tsukuba 305‐8506 Japan