Salinity stress test as a predictor of survival during growout in pacific white shrimp ( Litopenaeus vannamei)

Abstract

A high survival rate to a salinity stress test applied to 15-day-old shrimp postlarva (P15) is supposed to be associated with improved performance during growout, or at least during pond stocking. However, there is no direct evidence (e.g. correlation) for this association. The present study analyzed survival to a salinity stress for correlation to subsequent performance in 40 larval batches (individual spawns) that were cultured simultaneously under the same conditions, as a predictive criterion of survival during stocking and growout to juvenile stages. We also determined some osmoregulatory capacities (gill area, Na +/K +-ATPase) associated with survival to the salinity stress test. The activity of Na +/K +-ATPase was higher in P15 subjected to lower salinities, but it did not reach significance in batches with higher survival to the salinity stress test. Survival to a stress test was positively correlated to P15 length ( r=0.62; P<0.001). The batches that had higher survival to the stress test also had higher survival during stocking, and a positive correlation was found between survival during stocking and survival to the stress test ( r=0.34; P<0.05). Thus, the salinity stress test applied to P15 was useful for predicting survival during stocking. However, it was not correlated to survival during growout ( r=0.04; P>0.05), or to size of juveniles during growout ( r=0.12; P>0.05), and thus it was not reliable as predictive indicator of performance (survival and growth) during growout under our experimental conditions. To our knowledge, these are the first published results of a relationship between survival to a salinity stress test applied to P15, and subsequent survival during stocking and growout assessed in controlled experiments.