Genotype by environment interaction and genetic parameters for growth traits in the Neotropical fish pacu (Piaractus mesopotamicus)

Abstract

Pacu (Piaractus mesopotamicus) belongs to the main native fish group of the continental aquaculture in South America. However, breeding programs are not available for this species. The estimation of parameters for different traits and in different environments are needed to set up optimized breeding programs Therefore, the objectives of this study were to estimate genetic parameters, to evaluate genotype by environment (GxE) interaction, and to identify morphotypes for growth traits in pacu, using an experimental data of a pedigreed population in Brazil. Data from 1380 individuals corresponding to 48 full-sib families for ten growth traits (initial weight, final weight, average daily gain, total length, standard length, head length, pelvis length, total height, head height, height at the posterior region) were evaluated in two distinct environments (breeding nucleus: env1; commercial fish farm: env2) at 15 months old. The average of final weight was 591.90 ± 274.60 g in env1 and 1035.80 ± 270.00 g in env2. The heritability estimates were registered as moderate/high, which ranged from h2 = 0.27 ± 0.12 to 0.74 ± 0.19. Correlation values between the growth traits were positive and low-high, ranging between 0.32 ± 0.04 to 0.96 ± 0.10 (phenotypic) and 0.33 ± 0.10 to 0.98 ± 0.01 (genetic). The genetic correlations between final weight and morphometric traits were significant and high (ranging from 0.70 ± 0.10 to 0.88 ± 0.05). Our results also revealed different morphotypes patterns for pacu (elliptical and rounded). GxE interaction was considered low for all traits between the two environments (correlation values of 0.80 ± 0.34 to 0.98 ± 0.23). In conclusion, our results suggest that growth traits can be incorporated into the breeding objective in pacu and superior animals evaluated at the breeding nucleus are predicted to be superior at the commercial environment. Moreover, selection can be driven according to the desired morphotype in pacu.