Use of molecular markers for monitoring the genetic effects of hatchery-based stock enhancement and for tracking hatchery-born individuals in the great scallop ( Pecten maximus )

The great scallop (Pecten maximus) is of high economical value, particularly in France and UnitedKingdom. Although great scallop fisheries are mostly based on the exploitation of natural beds, some stocks are seeded with hatchery-reared spat in order to ensure the sustainability of local fisheries. This is particularly the case in the Bay of Brest (France), where hatchery-based stock enhancement of P. maximus has been developed since 1983, in order to enhance the local population. However, The release of hatchery-born seeds might significantly impact the genetic diversity of local scallop populations. In the present study, microsatellites were used to monitor the genetic variability seeded great scallop populations, in order to evaluate the possible impact of hatchery-based stock enhancement on the genetic diversity of local populations. A limited but temporally persistent erosion of the genetic variability as well as a strong alteration of the natural gene pool were found in hatchery cohorts. However, the genetic diversity of seeded populations did not seem to decrease. Furthermore, molecular marker-based pedigrees were assessed, in order to identify hatchery-born individuals released in natural beds. Hatchery-born individuals were successfully assigned to their parents, thus opening new avenues for monitoring populations enhanced with hatchery-raised spat.