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Growth and survival of the pearl oyster Pinctada imbricata (Röding 1758) in supended and bottom culture in the Golfo de Cariaco, Venezuela

Abstract:

We evaluated growth and survival rates of Pinctada imbricata in relation to environmental changes during nine months in suspended and bottom culture in the Golfo de Cariaco, Venezuela. Juveniles, measuring 13 mm in length, were cultured using two methods, (1) in Spanish-type baskets suspended at 3-4 m in depth from a long line and (2) in baskets embedded on the scabed (7-8 m in depth). At monthly intervals, we quantified mortality and took a sample of oysters to determine shell length (dorsal-ventral axis) and the dry mass of the shell, muscle and remaining tissues. We also quantified the dry mass of fouling on the shells (a potentially important environmental factor). Survival rates were slightly higher in suspended culture (98-100%), although not significantly higher than on the bottom. The growth rate was higher in suspended culture than on the bottom culture, and the difference between culture methods was greater for tissue and shell biomass than for shell dimensions. At the end of the study, oysters measured 55 mm in shell length for oysters in suspension and 45 mm for those on the bottom. Although growth was not significantly correlated with any environmental factor, it tended to increase with increases in chlorophyll a during periods of upwelling, thus suggesting that phytoplankton abundance enhanced the growth of Pinctada imbricata. The pearl oyster Pinctada imbricata should be an excellent species for aquaculture activities, given its high rates of growth and survival in suspended culture and its economic importance in the Caribbean region.