SALINITY TOLERANCE OF HATCHERY-REARED POSTLARVAE OF PENAEUS-INDICUS MILNE-EDWARDS,H. ORIGINATING FROM INDIA

The effect of salinity (S) on growth, survival, total biomass and individual wet weight of Penaeus indicus postlarvae (PL), from broodstock originating from India, but reared through several generations in recirculating systems in Europe, was examined in the laboratory. Hatchery-reared postlarvae (PL7-22) appear to tolerate a wide range of salinities (5-40 ppt S). Although animals tolerate abrupt salinity changes of up to 10 ppt S, transfer from 30 ppt S to 10 and 5 ppt S without acclimation resulted in mass mortalities over a period of 24 h. PLs grown at 25 ppt without acclimation exhibited the best growth and survival between PL7 and PL22 (P<0.05). Following a 10-day acclimation period, the postlarvae reared at various salinities (10, 20, 30, 35, 40 and 50 ppt) displayed the best performance (growth, survival, total biomass) at salinities between 20 and 30 ppt from PL20 and PL60 (P<0.05). While postlarvae up to PL60 gain resistance to high salinities (40-50 ppt S), lower salinities (10 ppt S) were lethal for the postlarvae after the PL45 stage. In contrast to Red Sea P. indicus, high salinities of 40-50 ppt caused cessation in the growth, and reduced survival and biomass of the Indian postlarvae.