Seasonal differences in effect of broodstock diet on spawning success in the great scallop

Great scallop (Pecten maximus L.) broodstock collected at two different sea sons, spring (May) and winter (December), were given four different diets d uring conditioning. The spring group was spawned in late June, and the wint er group in February. The highest number of veligers in the summer spawning (30 millions per 10 broodstock), was produced using a diet consisting of 8 0% Tahitian Isochrysis galbana. In the winter spawning, broodstock given a diet consisting of 80% diatoms (Skeletonema costatum/Chaetoceros gracilis) produced the highest number of veligers (29 millions per 10 broodstock). Fe cundity and the number of egg-releasing individuals were higher in the earl y summer spawning (June) than in the winter spawning (February), however, t he total number of three days old veligers produced was nearly the same in the two seasons.