THE EFFECTS OF TEMPERATURE AND SALINITY ON GROWTH AND SURVIVAL OF JUVENILE TIGER PRAWNS PENAEUS-ESCULENTUS (HASWELL)

Juvenile brown tiger prawns Penaeus esculentus live in a wide range of inshore environments but how temperature and salinity affect their gr owth and survival is not known. Juvenile P. esculentus (10-12 mm carap ace length, CL) were examined at combinations of five temperatures (15 , 20, 25, 30 or 35-degrees-C) and six salinities (5, 15, 25, 35, 45 or 55 parts per thousand) over 50 days. Individual prawns were identifie d by uropod clips and their carapace moult increment (MI) and intermou lt period (IP) histories were obtained from exuviae. After 50 days, th e prawns had survived a wide range of temperature-salinity combination s. Survival was greater than 60% in waters 15 to 30-degrees-C and 15 t o 45 parts per thousands; and at 35-degrees-C between 25 and 45 parts per thousands. Combinations of extreme temperatures and salinities wer e lethal. Moult increment varied little between 20 and 35-degrees-C or with prawn size. By contrast, IP increased markedly with decreasing t emperature and to a lesser extent with prawn size and thus controlled growth rates. Fastest growth is estimated to be at 30-degrees-C and 30 parts per thousand. The condition of prawns, in terms of energy (21.0 to 22.8 kJ.g-1 ash free dry weight) and wet weight (WW) and dry weigh t (DW) to CL relationships varied little between treatments. The P. es culentus juveniles in this study, obtained from near the southern limi t of the species distribution, coped in temperatures and salinities th at were well outside those which they would normally encounter in the wild. Cool water is the major factor which restricts their distributio n to tropical and subtropical Australia. Because P. esculentus is a po tential aquaculture species, the implications of the above results for the culture of the species are discussed.