Criteria for assessing larval and postlarval quality of Pacific white shrimp (Litopenaeus vannamei, Boone, 1931)

Optimum shrimp larval quality is of primary importance to obtain maximum yields during larval and postlarval culture, as well as during stocking in ponds for further growout. The present study analyzed putative predictive criteria of larval quality at different stages for correlation to subsequent performance. Association of salinity stress test (SST) survival with larval morphological and biochemical characteristics was also analyzed. For these purposes, 36 larval batches (individual spawns) that were cultured simultaneously under the same conditions were evaluated for biochemical and morphological characteristics, and survival from stress tests. The experimental design consisted of two approaches: (1) dividing these batches in low versus high survival during culture or to salinity stress test and comparing variables between both groups and (2) correlation analysis between different variables. Significant correlations were obtained between survival to an ammonia stress test of zoea or "metamorphosis" to zoea and survival from nauplii to 1-day-old postlarvae (r=0.59 or r=0.73, P<0.01, respectively). In addition, survival from 1- to 15-day-old postlarvae (PL1 to PL15) was correlated to the salinity stress test applied at PL1 (r=0.42, P<0.05). Thus these criteria were useful for predicting larval and postlarval survival to further stages. However, other possible criteria, such as nauplii and PL1 biochemical and morphometric variables, were not reliable as predictive indicators under our experimental conditions. In addition, several characteristics of PL1, such as gill area, postlarva size, and acylglycerides and their associated fatty acid content were significantly higher (P<0.05) in batches of PL1 with high survival after a salinity stress test. (C) 2004 Elsevier B.V. All rights reserved.