1Hokkaido Research Organization Central Fisheries Institute, Yoichi, Hokkaido 046-8555, 2Chair of Marine Food Science and Technology, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, 3Department of Marine Biology and Sciences, Tokai University, Sapporo, Hokkaido 005-8601, 4Lake Saroma Fisheries and Aquaculture Co-operation Organization, Sakaeura, Tokoro, Kitami, Hokkaido 093-0216, 5Laboratory of Marine Food Science and Technology, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
The Japanese scallop Mizuhopecten yessoensis is a major fisheries resource in the Hokkaido and Tohoku regions of Japan. This species is farmed or fished in coastal areas such as Lake Saroma and Funka Bay in Hokkaido and Mutsu Bay in Aomori. Recently, at Lake Saroma, mass die-offs of cultured Japanese scallops have been frequently observed. Although these die-offs might be due to abrupt changes in habitat conditions, the relationship between environmental stress and die-off in scallops has yet to be clarified. To examine the phenomenon, we first attempted to elucidate the relationship between the concentrations of ATP and arginine phosphate in the adductor muscle of Japanese scallops reared under various environmental conditions and their vitality. The results indicated that scallop vitality was negatively affected when scallops were reared under conditions of high seawater temperature or low salinity. Under such conditions, a significant decrease in arginine phosphate was detected prior to a decrease in vitality score and ATP content. This reduction in arginine phosphate was also observed when scallops were reared under anoxic or oscillatory flow stress. Taken together, these results suggest that arginine phosphate concentration in the adductor muscle can be a good predictor of scallop die-off.