First-generation genetic drift and inbreeding risk in hatchery stocks of the wreckfish Polyprion americanus

The wreckfish Polyprion americanus is a component of directed and admixed species fisheries throughout its world range and has recently been identified for its aquaculture potential. Several wreckfish broodstocks were founded in Galician hatcheries in the last decade and are now approaching maturity. The combination of genetic markers with classic domestication strategies is a pertinent approach to preserve genetic variation and to slow down consanguineous-derived adverse effects. Genetic data from microsatellites used to characterize four Galician wreckfish stocks provide evidence of both, a significant interstock differentiation (7.60%) and a pronounced loss of allele diversity (26%) in 80% of the stocks. Such artificial sub-structuring linked to the erosion of gene diversity is most likely caused by sampling drift that stepped up from the North Atlantic population. Computer simulation of relatedness helps to appraise alternate breeding protocols to avoid uncontrolled inbreeding within stocks. We show that under a fixed number of breeders and a sex balanced contribution, two protocols consisting on randommatingamong broodstocks (ΔRxy=2.21%) or enhancedwith a wild sample (ΔRxy= 0.97%), are far more advantageous strategies to slow inbreeding in F1 and F2 than breeding protocols within stock (ΔRxy= 6.6%).

This work was supported by the Spanish Institute of Oceanography (I.E.O., Project GENMOL2). Authors are indebted to the staff of IEO-Vigo, IGAFA (José Luis Rodríguez Villanueva), Luso-Hispana de Acuicultura (Alejandro Sanchón and Antonio Pizarro) and Aquarium Finisterrae (Antonio Vilar), for kindly supplying samples of the hatchery stocks analyzed. N.R.D. Matusse was supported by Ministry of Science and Technology of Mozambique (MCT) through a predoctoral grant of the scholarship program for postgraduates from Mundial Bank/International Development Association (IDA).

Peer reviewed