Growth of transplanted mangrove oyster, Crassostrea gasar, (Mollusca, bivalvia) in wooden trays
From June to September 2004 we studied the survival and growth of the mangrove oyster, Crassostrea gasar transplanted from mangrove serial roots to wooden trays suspended at the intertidal area of Onne, Rivers State, Nigeria. Survival depended on stocking sizes. Oyster seed between 0.2-1.2 g, 1.6-4.8 g and 5.0- 8.0 g had survival rates between 47.0, 76.6 and 68.7% respectively. The growth rates obtained for oyster seeds for the same size range gave 0.43, 0.28 and 0.22% respectively. Analysis of variance showed that there were no significant differences (p> 0.05) in the growth of oysters between the trays. Smaller sized oyster seed had higher growth rate but poor survival rate, with oyster seeds of between 1.6 and 4.8 g (averagely 3.2 g) having the highest growth and survival. This size range therefore appears to be the optimum stocking size range to obtain a survival rate of 70% and above depending on optimum environmental conditions.
Keywords: Mangove, oyster, Crassostrea gasar, seeds, Nigeria