Genetic parameters for economically important traits in yellowtail kingfish Seriola lalandi

The aim of the present study was to estimate genetic parameters for body and carcass traits, visual condition score, and deformity in yellowtail kingfish Seriola lalandi, an emerging aquaculture species in Australia. These novel data and genetic parameters are required to solve the problem of how to conduct efficient selection in this and related species. Analyses were performed on a total of 400 data records collected from a yellowtail kingfish breeding population at Cleanseas Tuna Ltd. farm. They were progeny of 22 full- and half-sib families (eight sires and six dams). Six newly developed and four published microsatellite markers were used to construct the pedigree. Genetic parameters were estimated using average information algorithm in ASReml with a multiple trait model. Fixed effects included sex, seal bite and deformity status. Random effects were the additive genetics of individual animal, and maternal and common environmental effects (i.e., dam-tank effect arising from a short period of separate rearing of offspring that came from two different broodstock tanks). The estimates of heritability for body and carcass traits were moderate (h²=0.15 to 0.30, s.e. ranging from 0.09 to 0.19). Fillet fat content showed an unusually high heritability (0.94±0.21) with a standard animal model, but was only moderate (0.41±0.26) when tank and dam were included as random effects. The estimate for condition score was 0.15±0.11, whereas the heritability for deformity was close to zero (h²=0.02). The genetic correlations between body and carcass (fillet weight and fillet yield) traits were high and positive (0.57 to 0.94, s.e. 0.05 to 0.46). Genetic correlations between body traits and condition score were moderate to high and positive (i.e. favourable). These results suggest that selection for high growth would result in concomitant increase in fillet weight, a carcass trait of paramount importance. It is concluded that there is substantial potential for genetic improvement of economically important traits especially growth performance and fillet weight in the current population of yellowtail kingfish.