Changes in the Condition Index and Biochemical Content of Adult Oysters (Ostreaedulis L.) Maintained under Hatchery Conditions

Abstract

Changes in the condition index and biochemical content of adult oysters, Ostrea edulis L., maintained under hatchery conditions have been compared with the corresponding changes in a field population. In the hatchery there was a fall in the condition index, the ash-free dry flesh weight and in the glycogen and protein content of the oysters. Over the same period of time the oysters in the field showed a rise in condition index, ash-free dry flesh weight and in glycogen and protein content. No significant differences (P ≤ 0·05) in the glycogen: protein (G: P) ratio were found between the field and hatchery oysters; the G: P ratio does not appear to be a good index of stress. The oysters in the hatchery were maintained at a higher temperature and probably had less total available food than those in the field. It is concluded that high temperatures and low availability of food are important stress factors to be considered when conditioning adult oysters in the hatchery.