Distribution and biology of commercial scallops (Chlamys) in the Northwest Pacific

Data on the three main commercial species of scallops (genus Chlamys) in the Northwest Pacific were collected from 1980 to 1988. Chlamys behringianus forms local concentrations in the Olyutorsky Gulf and off Karaginsky Island (Bering Sea), while C. albidus forms the densest concentrations off the northern Kuril Islands. Some stocks of C. rosealbus were found off North Primorye. Commercial concentrations of these species occur at depths of 50 to 200 m. Densities can reach 200 individuals m^-2. Underwater observations showed that scallop concentrations occur on level or slightly sloped surfaces. C. rosealbus can live as long as 28 to 30 years, with maximum increase in the linear increment occurring in 3- to 4-year-old scallops. Growth from this age is satisfactorily described by the von Bertalanffy equation. Time of spawning varies from March in the Sea of Japan through July in the Bering Sea. Individual fecundity varies from 2000 to 164 000 oocytes. The greatest portion of the stomach contents is detritus (up to 70% ), but diatoms, peridineas, remnants of crustacean larvae, algal spores, and sand were also found.