An 8-Year Breeding Program for Asian Seabass Lates calcarifer: Genetic Evaluation, Experiences, and Challenges

Abstract

Selective breeding for marine finfish is challenging due to difficulties in reproduction, larval rearing, and on-growth in captive environments. The farming of Asian seabass (Lates calcarifer) has all these problems and our knowledge of the quantitative genetic information (heritability and correlations) of traits necessary for commercial exploitation is poor. The present study was conducted to address this knowledge gap and to provide information that can be applied to sea bass and other aquaculture species. We carried out a comprehensive genetic evaluation for three traits (body weight, total length, and survival) collected from a breeding population for Asian seabass over an eight-year period from 2010 to 2017. Statistical analysis was carried out on 4,567 adult fish at 105, 180, 270, 360, 450, and 570 days post-hatch (dph). The heritabilities (h2) estimated for body weight and length using linear mixed model were moderate to high (0.12 to 0.78 and 0.41 to 0.85, respectively) and they differed between the measurement periods. Survival during grow-out phase was analyzed using threshold logistic and probit models. The heritability estimates for survival rate on the underlying liability scale (hL2) varied from 0.05 to 0.21. When the observed heritability obtained from the linear mixed model was back-transformed to the liability scale, they were similar but not significant. In addition, we examined effects of genotype by environment (G × E) interaction on body traits. The genetic correlation for body weight between tank and sea cage cultures were high (0.91–0.94) in the first and second rearing periods (180 and 270 dph) but the correlation was decreased to 0.59 ± 0.33 at 360 dph. This suggests that the genotype by environment interaction is important for body traits in this population. Furthermore, the genetic correlations of body weights between different measurement periods were moderate but different from one. This suggests that body weights measured at different time points may be different traits and selection for improved early weight may not capture all genetic expressions in subsequent rearing periods in Asian seabass. Selection of the nucleus in sea cages may produce genotypes that do not perform equally well in tanks, although this deserves further studies to determine a suitable selection environment and optimize the breeding program. This paper discusses challenges encountered during implementation of the selection program for L. calcarifer.

Harnessing genomics to fast-track genetic improvement in aquaculture

“…Mass spawning causes practical challenges such as uneven parental contribution and difficulty in tracking individual pedigrees, which can result in inbreeding 51 . Although multiple interventions are possible to enable pedigree tracking (for example, pair spawning or stripping using hormonal induction) 52 , genetic markers are frequently applied to track stock relatedness to minimize loss of genetic diversity within a closed breeding nucleus 51 .…”

Resistance to Streptococcus iniae and its genetic associations with traits of economic importance in Asian seabass (Lates calcarifer)

“…Fish used in this study were sampled from the second generation (G2) of the mainstream selection programme for increased growth for Asian seabass at MRDC, RIA3, Vietnam. A detailed description of the breeding programme from mating to final harvest is given in Khang, Phuong, Dat, Knibb, and Nguyen (). Briefly, in each generation full‐ and half‐sib families were produced by stripping sperm from males and eggs from females.…”

Genome-Wide Marker Analysis for Traits of Economic Importance in Asian Seabass Lates calcarifer

“…Fin tissue samples of 188 individual fish were from 28 families (16 full-and 12 halfsibs) produced in the second generation of an Asian seabass population, which has been undergoing 8-year selection (or two generations) for increased body weight [1]. The experimental fish were produced in 2017 by single-pair mating (one male to one or two females) using the induced breeding method.…”

“…A genetic improvement program for Asian seabass (Lates calcarifer) was established in 2007 to improve traits of economic importance for this species [1]. As the first step of any selective breeding program, we conduct a quantitative genetic analysis of a range of traits.…”