Genetic assessment of three gilthead sea bream (Sparus aurata L.) populations along the Spanish coast and of three broodstocks managements

The gilthead sea bream (Sparus aurata L.) is one of the most important Sparid farmed in Europe, especially in the Mediterranean area. However, efficient breeding programs for this species are scarce and very little, and it is known concerning their population structure. The present study was mainly designed to genetically characterize, by microsatellite markers, three gilthead sea bream populations sampled along the Spanish coast (Cantabrian Sea, the Atlantic Ocean and Mediterranean Sea) and their progeny with the aim of studying its genetic variability and its genetic structure. Moreover, we evaluated different strategies of broodstocks management (breeders’ number, origin and sex combination) on parental contributions and on effective breeding numbers. That number of breeders in the stock was of great importance to the maximization of contribution since the larger broodstock resulted in larger proportion of parents contributing. Variation in dam and sire spawning incidence and in number of progeny produced per dam and per sire was translated into reduced effective breeding numbers and consequently into expected increased inbreeding rates. Our results highlight the high genetic variability of the studied sea bream populations, as well as the existence of three genetically differentiated populations along the Spanish coast. These findings should be relevant for the establishment of successful breeding programs in aquaculture of the gilthead sea bream.