Genetic parameters for body weight and survival in the Pacific White Shrimp Penaeus (Litopenaeus) vannamei affected by a White Spot Syndrome Virus (WSSV) natural outbreak

Abstract

White Spot Syndrome Virus (WSSV) is a disease that causes large economic losses in the shrimp industry. Genetic improvement is a strategy for controlling some diseases in aquaculture. Genetic parameter estimates for body weight and survival in the presence of WSSV have been obtained from laboratory challenge experimental designs, but there are no studies in the presence of a WSSV natural outbreak. The aims of this study were (1) to estimate genetic parameters for body weight at 19weeks of age and survival from 10 to 19weeks of age in the Pacific white shrimp (Penaeus (Litopenaeus) vannamei) in a pond affected by a natural outbreak of WSSV, and (2) to compare these estimates with those obtained from two ponds where no WSSV was present. The estimate of the heritability for body weight was smaller in the presence of WSSV (0.09 to 0.11) than in ponds with no WSSV (0.15 to 0.33). An increase in body weight residual variance was observed in the pond affected by WSSV. The estimate of the heritability of survival for the pond affected by WSSV (0.06±0.03) was larger than that estimated in the unaffected ones (0.00 to 0.02), suggesting a minor change in the additive genetic expression of this trait. Heritability estimates for body weight and survival are the first ones obtained in a population affected by a WSSV natural outbreak using pedigreed information. Results suggest that selection response for survival at harvesting in the presence of WSSV would be very small, and that selection response for body weight in the same condition would be smaller than in the absence of WSSV. Studies regarding the implications of including these and other important traits in shrimp breeding programs in the presence of WSSV are necessary.