Résumé
The analysis of samples from the first to the third generations of hatchery stocks (G1, G2, G3), of black pearl oysters,
P. margaritifera, has been investigated using 18 protein loci to determine the genetic variation compared to a wild sample (WS). A reduction of 17% and 18% in the number of alleles was estimated in G2 and G3, respectively. Seven alleles (of the total of 45 alleles) were not found in the wild sample. The change of selective constraints in hatcheries compared to the wild environment can account for these new alleles. The observed heterozygosities were maintained (Ho: wild=0.237 and hatchery=0.236 to 0.269). Inbreeding depression did not occur in any hatchery sample although an increasing excess of heterozygotes was observed in G2 and G3 samples. This could be explained by selective effects through the choice of broodstock and change of the selective forces in an artificial environment.