1. Shiga Prefectural Fisheries Experiment Station, 2138-3, Hassaka, Hikone, Shiga 522-0057, Japan
2. Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Nikko, Tochigi 321-1661, Japan
3. Uryu Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Moshiri, Horokanai, Hokkaido 074-0741, Japan
4. Lake Biwa Museum, 1091 Oroshimo, Kusatsu, Shiga 525-0005, Japan
5. Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
6. Maizuru Fisheries Research Station, Field Science Education and Research Center, Kyoto University, Nagahama, Maizuru, Kyoto 625-0086, Japan
7. Division of Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan