Geographical origin of individual breeders from gilthead sea bream (Sparus auratus) hatchery broodstocks inferred by microsatellite profiles

Determination of seed origin is essential for a sustainable use of aquatic resources, in order to protect local biodiversity in restocking programmes or culture-based fisheries and as a precautionary approach to mitigate the genetic impact of accidental escapees from fish farms. Tracking the geographical origin of individual breeders is also useful to fish farmers, whose information on their own broodstocks is sometimes fragmentary. Gilthead sea bream (Sparus auratus) broodstocks from two Italian commercial hatcheries were genetically characterized using four microsatellite loci. The most likely geographical origin among five natural populations was inferred for each single breeder through Bayesian statistic-based methods. Results show a mixed and highly heterogeneous origin of the broodstocks analysed, and revealed a high percentage of Atlantic individuals among breeders.