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

In gilthead sea bream, flesh quality traits such as body composition and texture directly influence yield of final product and consumer preferences so they should be considered in the breeding goal. However, strategies that involve the development of selection schemes for these traits of economic interest are scarce. Taking into account these circumstances, in this study the effect of the origin of the broodstock on the major flesh quality traits was analyzed at harvest size (690days post-hatching) and genetic parameters (heritabilities and genetic correlations) were estimated as well as their correlations with harvest weight. For this purpose, a population of farmed gilthead sea bream was obtained from three broodstock of different geographical origins along the Spanish coast [Cantabrian Sea (CAN), the Atlantic Ocean (ATL) and Mediterranean Sea (MED)]. Parental assignments between breeders and their offspring were carried out a posteriori using a microsatellite multiplex (SMsa1). In the offspring, raw flesh composition (muscular collagen, fat, moisture and protein contents) were determined (n=700). Textural parameters (hardness, cohesiveness and derived traits) were measured in an industry relevant number of offspring (n=890) for the first time in this species. The origin had an effect on muscular fat content as well as on hardness and derived textural parameters. Fish from MED showed the lowest fat percentage and those from CAN the highest values for textural parameters. Differences among origins could be explained through their different genetic backgrounds. However, the effect of the origin could be affected by environmental conditions in the initial facilities, where each origin was reared separately, and by genotype x environment interactions. Heritabilities were medium for muscular fat (0.31±0.08) and moisture (0.24±0.07). The genetic correlation between them was very high and negative (−0.99±0.02). Selection for harvest weight may lead to an increase in fillet fat percentage due to the genetic correlation between the two traits (0.29±0.14). Hardness showed a medium heritability (0.21±0.06) and an unfavourable negative genetic correlation with harvest weight (−0.34±0.14). 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 has an effect on muscular fat content and textural parameters. Moreover, genetic parameters are estimated for this traits which are scarce in this species.