Spat collection of the pearl oyster ( Pinctada margaritifera cumingii) in French Polynesia: an evaluation of the potential impact on genetic variability of wild and farmed populations after 20 years of commercial exploitation

Abstract

Pearl production, based on the aquaculture of the blacklipped pearl oyster Pinctada margaritifera, is an essential economic activity in French Polynesia. Production relies almost exclusively on the collection of wild spat, which makes the activity very dependent on natural resources. A good knowledge of these resources is thus essential for the rational management of farmed and wild populations. In this study, we analysed the structure of genetic variability, in wild and farmed populations distributed on four atolls from the Tuamotu–Gambier archipelago using four anonymous nuclear loci. No genetic difference was observed among samples from wild populations collected from Northern Tuamotu to Southern Gambier. This suggests that large-scale dispersal, either due to the absence of barriers to natural larval migration, or to the transport of collected spat for pearl production. No significant differences were found between wild and adjacent farmed populations for the number of alleles and observed heterozygosity, which supports the conclusion that current methods used to collect wild spat are unlikely to affect the genetic composition of pearl oyster populations. However, a more accurate picture of the situation might be obtained with more variable markers.