Optimizing Broodstock Conditioning for the Tropical Clam Anomalocardia brasiliana

The tropical clam Anomalocardia brasiliana is a commercially important bivalve living along the south Atlantic coast of Latin America. Harvest of natural stocks is the principal method for supplying market demand—the market average price ranging from 5 to 10 US$ per kilogram of meat. As a first step in the development of hatchery techniques for A. brasiliana seed production, this study examined the effects of temperature and salinity on conditioning broodstock for spawning. Two treatments tested conditioning at 25°C at salinities of either 30 or 35. A third treatment examined the effects of an initial 10-day conditioning at 16°C followed by a gradual temperature increase to 25°C at a salinity of 35. As a control, clams were sampled from the wild over the same experimental period. Tissue samples were taken at the initiation of the experiment and at 15, 30, 45, and 55 days of conditioning and examined histologically to determine changes in the sexual development of the clams. Four reproductive stages were identified during the experimental period: gametogenesis, mature, spawned, and absorption. The treatment with the initial 10-day conditioning period at 16°C demonstrated that it is possible to synchronize gamete development in both males and females to result in the maximum proportion of mature broodstock at 55 days of conditioning.