ABSTRACT
The scallop Patinopecten yessoensis is a mollusk that has been of considerable commercial importance in Japan for a long time. Processed scallop meat has been exported from Japan to China for about 250 years. It is a cold-water species, occurring above about 35 N latitude in the northwest Pacific Ocean on the coasts of the Kuril Islands, Sakhalin, Hokkaido, northern Honshu, and the northern Korean peninsula. Some gonadal development occurs in 1-year-old scallops, but spawning does not usually occur until the scallop is 2 years old. A 2-year-old female can produce as many as 80 to 110 million eggs, and a 3-year-old, 110 to 130 million eggs. Gonadal development starts in midautumn and by mid-February to mid-March the gonads are ripe and ready to spawn. Constraints on scallop production in Japan include shell-inhabiting or attached organisms, parasites, predators, occasional mass mortalities, overstocking, and shellfish poisoning caused by plankton blooms.
