Effects of Water Temperature on Catabolic Losses of Meat and Condition Index of Unfed Pearl Oyster Pinctada fucata martensii

Abstract

To determine the effects of water temperature on the catabolic losses and condition index of unfed pearl oysters Pinctada fucata martensii, pearl oysters were held unfed at water temperatures of 15, 22 and 28°C for 60 days under laboratory conditions. Cumulative mortality was within 7% and whole weight decreased less than 7% during the experimental period. Both dry meat weight and condition index gradually decreased during the 60-day unfed period. The decreasing rate of condition index and dry meat weight increased with increasing water temperature. There was a positive close correlation between water temperature and catabolic losses of dry meat weight, carbon and nitrogen content from pearl oysters held unfed for 60 days (r≥0.93 in all instances). These results suggest that the degree of catabolic losses of pearl oysters depended on the ambient seawater temperature under the unfed condition. Unfed pearl oysters can survive by utilizing energy reserves from their meat for up to 60 days. However, the nutritive status of pearl oysters indicated the condition index, and the carbon and nitrogen content of dry meat declined during the unfed period, particularly at 28°C. © 1995, The Japanese Society of Fisheries Science. All rights reserved.