Bull. Jpn. Soc. Fish. Oceanogr. 80(4), Page 283-288, 2016   Effects of marine environment on adductor muscle weight of bottom cultured Japanese scallop Mizuhopecten yessoensis in the coastal area of northeastern part of Hokkaido, Japan Akiyoshi Shinada1† and Koji Miyoshi2 1 Central Fisheries Research Institute, Hokkaido Research Organization, Hamanaka-cho, Yoichi, Hokkaido 046-8555, Japan 2 Abashiri Fisheries Research Institute, Hokkaido Research Organization, Masuura, Abashiri, Hokkaido 099-3119, Japan † E-mail: shinada-akiyoshi@hro.or.jp To clarify the effects of the marine environment on the adductor muscle wet weight of bottom-cultured Japanese scallop Mizuhopecten yessoensis in the coastal area of the northeastern part of Hokkaido, Japan, monthly surveys were conducted from March 1992 to December 2012. Spearman’s rank correlation coefficients were calculated between mean adductor muscle wet weights from August to October in four-year-olds and monthly marine environments such as water temperature, Chlorophyll a concentration as an indicator of food, and the sea level difference between Wakkanai and Abashiri as an indicator of Soya warm current from April to July. Significant positive correlations were found between mean adductor muscle wet weights and all marine environments in April. We used a generalized linear model (GLM) to statistically analyze these field survey data. The model used water temperature, Chlorophyll a concentration, and sea level difference in April as explanatory variables was selected by AIC. These results suggest that marine environments in April are important for changes in adductor muscle wet weight of bottom-cultured Japanese scallop in the coastal area of the northeastern part of Hokkaido. Key words: scallop, adductor muscle, water temperature, chlorophyll, soya warm current