Growth curve estimation of the oyster Crassostrea brasiliana in the mangrove and a proposal to their sustainable extraction in Cananeia Estuary, SP, Brazil

Abstract

The present paper describes the results of a study on the surviving and growth of the oyster Crassostrea brasiliana in the natural environment. The study was carried out from March 2000 to February 2001. A total of 140 oysters, selected in two stations (1 and 2) and fixed on the roots of Rhizophorae mangle, were monthly measured over 12 months. In the two stations, it was observed that a population (28%) reached the minimum commercial size at the age of 19.52 and 18.81 months, respectively in stations 1 and 2, and another one (72%), at the age of 28.28 and 25.61 months, respectively in stations 1 and 2, showing how slowly the majority of the oysters grow in the natural environment. Then, it was possible to realize the fragility of the equilibrium of this natural resource, when exposed to an excessive extraction. Considering the natural mortality observed during the study as near 20% plus 10% on account of other elements, it was estimated that the annual maximum sustainable production through the extrativism might be 787,841 dozen of oysters, since the total estimated stock mentioned before is  preserved. The introduction of this information can be useful for the management of the mangrove oyster production in Cananéia estuary, reducing the impact on the natural stock and assuring a sustainable production, and so consolidating the activity, which results in benefits for the community.