Effects of age, size, and season on growth of soft tissue in the oyster Crassostrea gigas (Thunberg, 1793)

This study describes potential effects of age, size, and season on the relative allocation of resources to meat and shell growth in Crassostrea gigas. Two oyster size groups (slow- and fast-growing oysters) of the same cohort were followed over 2 years. Analysis of covariance detected significant differences in meat weight between groups, seasons, and years. Fast-growing oysters have more meat per gram of shell than do slow-growing, suggesting greater efficiency of the conversion of consumed energy to tissue in the former. Seasonal changes in both sets in meat were related to productivity pattern of phytoplankton, with the highest values of chlorophyll a in early summer and minimum in early winter. Differences observed between years in meat content of oysters are attributable both to variability in environmental conditions and to the effect of age.