Relationships Between Possible Available Food and the Composition, Condition and Reproductive State of Oysters from Galveston Bay, Texas

Possible food for oysters (Crassostrea virginica ) was measured as a food index. The food index was defined as the percentage food (food = lipid + carbohydrate + protein) in the total seston. Highest condition index values (C.I. = dry weight/mantle volume x 100) of oysters were not related to the time of greatest available food. The food index was, however, correlated with the gonadal index (G.I. = gonadal thickness/adductor muscle diameter) of oysters. The greatest amount of available food was present during the time of presumed greatest energy demand, namely the period of gametogenesis. The concept of the storage cycle is applicable to Crassostrea virginica . Changes in the oysters' composition and in condition and gonadal indices support the hypothesis that stored glycogen is converted into the lipid reserves of the developing eggs.