Genetic parameter estimates and identification of SNPs associated with growth traits in Senegalese sole

Breeding programs are essential for aquaculture. The present study was conducted to investigate the genetic parameters of four growth traits in Senegalese sole. Families were produced by mass spawning (n = 2171 offspring) from an industrial broodstock. Weight, total area, standard length and width (the two latter measured directly on the fish and by image analysis) were determined before the on-growing stage (age - 400 d) and at harvest (-800 d) in RAS. Phenotypic data are presented and discussed. Females grew faster than males and a high variation of sex ratios by family was observed. Heritabilities were high for all traits ranging from 0.568 to 0.609 at 400 d and from 0.424 to 0.500 at 800d. The genetic correlations between traits were very high (>0.94) at both ages. Genetic estimates for traits measured in vivo and by digital image analysis were similar. To investigate genomic regions associated with these growth traits, a low-density array using a set of 60 single nucleotide polymorphisms (SNPs) distributed in 17 linkage groups was designed. Using samples from wild fish, a total of 49 assays for SNP analysis were validated. The association analysis was carried out using two fast-growth families and two slow-growth families (n = 279). Two significantly-associated SNPs with most of the traits at both ages were detected. They were located in the general transcription factor 3C polypeptide 4 (gtf3c4) and the mitochondrial fission process protein 1 (mtfp1). Results are of high relevance for genetic breeding programs in this species.