Density estimate of the mangrove oyster, Crassostrea spp. stock in Mandira Extractive Reserve, Cananéia, São Paulo State, Brazil (25ºS; 48ºW)

Abstract

The estuarine lagoon system of Cananéia holds the greatest natural stock of the mangrove oyster in the state of São Paulo. Inside this system lies the Mandira Extractive Reserve that comprises an area of around 1,165 ha. The purposes of the present study were to estimate stock densities of mangrove oysters, Crassostrea spp. and compare its current situation to data collected in the same location in 1999, and subsidize the actions of the responsible agencies for the management of natural resources in that Reserve. Eight representative plots along natural stocks were studied along July 2005. They allowed a total production estimation of 458,683 dozens of oysters in the rivers and tidal creeks, 8.7 % of commercial size (> 50 mm in hight), corresponding to 23,943 dozens. These data point out a reduction of 19.7 % in comparison to those obtained in 1999. An occasional increment in the market demand will pressure for an increasing extraction and, consequently, depletion of the natural stocks. Aiming to the sustainability of activity, it is suggested the adoption of control measures of the resource exploitation, such as respect to annual prohibition (the “defeso”, the closure period) and the exclusion of extractive on oysters below the legal minimum size (50 mm).