Modeling of resistance to salinity shocks of Penaeus vannamei postlarvae

The notion of penaeid shrimp postlarvae quality, which implies a survival potential, is still a subjective parameter. The zootechnical criteria and the visual observations arc not sufficient to evaluate the physiological condition of the hatchery reared postlarvae. The resistance of postlarvae to salinity shocks is a representative criteria of their condition. The goal of this study is to present a non-linear regression model at 2 variables (size, salinity) for the P. vannamei postlarvae resistance to salinity shocks. Between the second and the twentieth day after metamorphosis; 5 salinity shocks (20, 15, 10, 5 and 20 parts per thousand) were tested daily, each one with 50 postlarvae. Survival rates were recorded after 2 hrs. Concurrently, the postlarvae growth in the rearing tank was studied by the daily measurement of 30 individuals. The survival to the salinity shocks improves with the size which increases linearly.