GROWTH AND SURVIVAL OF POSTLARVAL PENAEUS AZTECUS UNDER CONTROLLED CONDITIONS OF TEMPERATURE AND SALINITY

Abstract

Two types of study [long dash]24-hour survival and 30-day growth[long dash]have been used to test the combined effects of salinity and temperature upon acclimated postlarval Penaeus aztecus (brown shrimp). The 24-hour survival tests indicated that postlarvae had wide tolerance limits to both factors. One hundred per cent of the postlarvae survived all combinations of 20[degree] to 32[degree] C temperatures with salinities of 5 to37%, however, 100% mortality occurred at salinities of 5%, or below when temperatures were above 34[degree] or below 15[degree] C. Survival in growth studies using 4 temperature levels (11[degree], 18[degree], 25[degree], and 32[degree] C) combined with 5 salinities (2, 5, 15, 25 and 35% ) was similar, except for somewhat greater mortality at 32[degree] C. The greatest observed growth occurred at 32[degree] C, while essentially no growth was observed in post-larvae held at 11[degree] C. The survival data indicate that brown shrimp postlarvae were able to withstand wide variation of both salinity and temperature. Growth also occurred within a wide salinity range, but was restricted to a much narrowed temperature range than that at which good survival was observed. Although growth rate was apparently more affected by temperature than by salinity, higher salinities may be more favorable than lower ones as the temperature limits are approached. Both the tolerances and the food requirements would seem to be of considerable importance to the animal in the estuarine phase of its life history.