Abstract
Information on phenotypic and genetic (co)variance for production traits in turbot is required to improve breeding programs. So far, information on morphometric growth traits is sparse and completely lacking on quality carcass traits like fillet weight or fillet yield for turbot. As part of a long-term study we explored the phenotypic and genetic (co)variance of 16 biometrical and carcass traits of three different European turbot strains. Fish were reared under commercial grow-out conditions, including size grading. We used molecular relatedness (MR) methods based on genotyping with 96 microsatellite markers and animal models. We included an adapted condition factor for Pleuronectiformes (FCI) and average daily weight gain (ADG) between the ages of 300 and 500 d post-hatch (dph) for their potential correlation with body weight at harvest. Heritability estimates for all traits were low to medium (0.04–0.29) when strains were jointly analyzed. Separate analysis of strains yielded higher heritability estimates (0.12–0.43). Genetic correlations between weight-related traits were highly positive (0.70–0.99), while runs with yield and ratio traits often resulted in unreliable estimates of genetic correlation due to high standard errors. Body weight (), fillet yield (5), and dressing percentage () are particularly promising selection traits for turbot breeding.
Highlights
Aquaculture production of turbot (Scophthalmus maximus) has been steadily increasing over the last years, especially in the PR China (64 000 t in 2013), which is the biggest producer worldwide (FAO, 2012)
As part of a long-term study we explored the genetic and phenotypicvariance of 16 biometrical and carcass traits of different turbot strains under commercial grow-out conditions using molecular relatedness (MR) and restricted maximum likelihood (REML) methods
Mean fillet without skin (FW) was 227.5 g, which translates to a mean fillet yield (FY%) of 29.7 %
Summary
Aquaculture production of turbot (Scophthalmus maximus) has been steadily increasing over the last years, especially in the PR China (64 000 t in 2013), which is the biggest producer worldwide (FAO, 2012). In Europe, turbot is mainly valued as a high-priced food fish on the upscale gourmet market, with the vast majority of production taking place in Spain and Portugal. Turbot is primarily sold whole, with a smaller portion of aquaculture production being sold either gutted or filleted (Turbot Species Leaflet – European Commission, 2016). Regardless of these different marketing strategies, the improvement and harmonization of growth traits remains one of the biggest and economically most relevant challenges of turbot breeding programs. Studies on heritability and genetic correlations in turbot have mostly been focused exclusively on body weight as the trait of the highest economic value (e.g., Gjerde et al, 1997; Guan et al, 2015) and have
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