Evaluation of two genetic lines of Pacific White leg shrimp Liptopenaeus vannamei selected in tank and pond environments

Running multiple breeding programs for the same species requires a high level of investment and management; hence, to date there have not been any attempts to develop specialised genetic lines for different environments in any aquaculture species. This study made the first attempt to conduct a comprehensive genetic evaluation of the breeding programs for improved growth in two Liptopenaeus vannamei lines selected in both tank and pond environments over three generations from 2014 to 2017. The pedigree included 95,696 shrimp individuals (offspring of 352 common sires and 423 dams). Genetic analysis was carried out separately for each line and environment, using restricted maximum likelihood and mixed model approaches. The estimates of heritability for body weight were comparable between the lines (Line 1 was selected in tank and Line 2 in pond). In each line, the estimates of heritability for body weight were environment-dependent. The common full-sib effects (c(2)) were large in both tank and pond environments (ranging from 16 to 21% across traits). There were, however, no significant differences in the c(2) estimates between the two lines and between the two environments. The between-environment genetic correlations, as a measure of genotype by environment interaction, were low in both lines. Genetic gain measured as estimated breeding values (EBVs) was greater in Line 2 (selected in pond) than Line 1 (selected in tank); the gain expressed in genetic standard deviation unit (SDA) for body weight was 3.27 SDA in pond vs. 1.70 SDA in tank in the latest generation (2017). It is concluded that selection in pond achieved greater genetic gain than selection in tank when their descendants were tested in both environments (i.e., tank and pond).