Affiliation: | ;Department of Biology, Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido 041-8611, ;Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, ;Port of Nagoya Public Aquarium, Nagoya, Aichi 455-0033 and ;Toya Lake Station for Environmental Biology, Faculty of Fisheries, Hokkaido University, Abuta, Hokkaido 049-5723, Japan |