Stock evaluation of the mangrove oyster, Crassostrea brasiliana, in Cananéia lagoon estuarine system (25ºS; W48º)

Abstract

The Cananéia lagoon estuarine system, located at 25°S latitude on the Atlantic Coast of South America, is considered one of the greatest producers of oyster from natural stocks in Brazil. The purpose of this paper is to estimate Crassostrea brasiliana (Lamarck, 1819) population size in Cananéia mangroves. Samples of oysters and other information were collected on the right and left margins along Cubatão Sea, Cananéia Sea, Trapandé Bay and Ararapira Channel (in the vicinity of Marujá), from August 1998 to January 1999. The mangrove forest was divided in four areas (1, 2, 3 and 4), each one subdivided in parcels. The oysters settle, preferably, on air roots of red mangle Rhizophora mangle, disposed on the first and second rows along the external fringe of tide water. Results about the mangrove forest composition, tree diameter at breast height, root occupation diameter, tree density and height, oyster number/root area, and oyster number/parcel were obtained. It was estimated that Cananéia mangrove has a population of 11,268,954 dozen oysters, among which only 8.6% presented commercial size (>5 cm in height). Nowadays, the harvest of oyster from the natural grounds is probably reaching the sustainable capacity of explotation. This fact may endanger the sustainability of those stocks in the next years. The results of this research shall contribute to the adoption of a rational extraction policy.