Estimates of heritabilities and genetic correlations of carcass quality traits in a reared gilthead sea bream (Sparus aurata L.) population sourced from three broodstocks along the Spanish coasts

Carcass quality traits such as visceral fat and fish morphology have a direct influence on final product and consumer preferences, especially in species as sea bream that are sold as whole fish. Nevertheless, strategies that involve the development of selection schemes for these traits of economic interest in gilthead sea bream are limited. In this study the effect of the origin of the broodstock on carcass quality traits was analyzed in harvest size (690days post-hatching) gilthead sea bream for the first time. For this purpose, a population (n=890) of farmed gilthead sea bream obtained by industrial mass-spawnings from broodstocks from three different origins [Cantabrian Sea (CAN), the Atlantic Ocean (ATL) and Mediterranean Sea (MED)] was analyzed for condition factor, visceral fat content, dressing weight, dressing percentage, fillet weight and fillet percentage. Moreover, with the goal of estimating genetic parameters (heritabilities and genetic correlations) for carcass quality traits as well as their correlations with growth (harvest weight and length), a reconstruction of pedigree was carried out a posteriori. The origin had an effect on several carcass traits. Fish from ATL showed the lowest visceral fat percentage, dressing weight and percentage and those form CAN the lowest condition factor. These differences among origins can be explained through their different genetic backgrounds but also by environmental conditions in the initial facilities, where each origin was reared, and the derivate genotype × environment interactions. All carcass traits showed medium heritabilities (ranging from 0.17 to 0.24) and were estimated with accuracy (standard errors from 0.05 to 0.07) except dressing (0.07±0.05) and fillet (0.11±0.05) percentage. Due to their genetic correlations, selection on weight could lead to an increase in condition factor (0.47±0.21) but, at the same, to an undesirable increase in visceral fat (0.42±0.20) and a decrease in fillet yield (−0.58±0.09). However, selection on length could improve dressing (0.87±0.07) and fillet weight (0.84±0.09). Alternatively, visceral fat content could be decreased by selection through condition factor (−0.46±0.16). All findings reported in this study should be relevant for the establishment of successful breeding programs in aquaculture of this species.This study proves the importance of the acquisition of a stock in sea bream since the studied origins of the broodstock had an effect on different carcass traits. Moreover, genetic parameters are estimated for these traits which are scarce for this species.