Season and method to select oyster seeds of Crassostrea brasiliana [Lamarck, 1819] in the lagoon-estuarine complex of Cananéia, São Paulo State, Brazil [25ºS ; 048ºW]

Abstract

Oyster seeds of Crassostrea brasiliana (Lamarck, 1819) were selected by two methods of hardening treatment. Seeds set on estrade 25 cm from soil and seeds disposed directly on the soil previously treated with gravel were hardened in intertidaI zone in the lagoon-estuarine complex of Cananéia. The hardening started in two periods of the year, one in the summer (from December/1979 to August/1980) and another one in the autumn (from April/1980 to December/1980). After 8 months of hardening, the seeds on estrade presented survival rates of 12.8% and 17.2% and the seeds hardened on the soil presented survival rates of 9.3% and 7.1%, for the treatments with beginning in summer and autumn, respectively. The final oyster average heights for estrade were 18.9 mm and 23.3 mm and for soil 23.5 mm and 25.8 mm, for the treatments with beginning in summer and autumn, respectively. The seeds hardened on estrade showed higher survival rate during the two periods, comparing with the treatment on the soil. From the obtained results, it was possible to conclude that the two methods employed, estrade and soil, and the periods, December to August and April to December, are applicable for hardening treatment.