The effect of water temperature on spawning induction, larval development, spat settling and its growth of the cockle shell, Fulvia mutica, were investigated to obtain the basic data for effective seed production. The eggs, which were randomly divided into 6 groups of water temperatures of 14, 17, 20, 23, 26 and 29°C, were transferred into 1 L beaker, respectively. The relationships between the water temperature and the required time (1/h, hour) by each egg developmental stage were calculated. Biological minimum water temperature and the cumulative water temperature until egg development of the veliger stage were calculated to be 0.1°C and 397.3°C, respectively. The optimal water temperature for developmental bioassay of F. mutica was clarified to be 23°C. The required time for the embryo to become veliger larvae was 20 hours at 23°C.
