VARIABILITY IN GROWTH AND SURVIVAL OF EARLY POSTLARVAL SHRIMP (PENAEUS-VANNAMEI BOONE 1931)

Growth trials with early PL (postlarvae) suggested that growth and siz e variability may be used as sensitive indicators of PL quality. For P L produced from a broodstock population in which IHHNV (Infectious Hyp odermal and Hematopoietic Necrosis Virus) had been identified, growth was lower and size variability was greater than for PL produced from a broodstock population free of IHHNV. Histological examinations of PL confirmed that the slower growing PL were infected with IHHNV, and tha t the faster growing PL were free of intranuclear inclusions character istic of IHHNV infection. Survival of PL did not differ between the tw o populations. Differences in both survival and growth between batches of PL within populations were significant but did not mask difference s in growth between the populations. Growth of early PL was exponentia l rather than linear and was appropriately characterized by the instan taneous growth rate. An additional growth trial conducted with juvenil e shrimp indicated that differences observed in PL growth between the two populations continued to be expressed during juvenile growth. Corr elations of PL growth to larval survival and duration suggested that l arval survival was a good indicator of PL quality but that larval dura tion was inadequate to predict growth of PL.