GENETICS OF INDIGENOUS AND TRANSPLANTED POPULATIONS OF PECTEN-MAXIMUS- NO EVIDENCE FOR THE EXISTENCE OF SEPARATE STOCKS

Genetic variation at eight polymorphic enzyme loci was investigated in 13 populations of the scallop Pecten maximus (L.) from a number of si tes in Scotland, UK and Brittany, France. Two of the populations had i nitially been transplanted, as spat, to Brittany from Scottish and Iri sh collection sites. In common with other studies of marine bivalves, an overall deficiency of heterozygotes was observed, but genotype freq uencies of transplanted populations were generally in agreement with t he Hardy-Weinberg model indicating little post-transplant selection. T here was high genetic similarity among all the populations surveyed an d no overall differences between the Scottish and Brittany samples. Th e results are discussed in relation to contrasting evidence, derived f rom studies on the reproductive cycle of P. maximus and the genetics o f Aequipecten (Chlamys) opercularis (L.), which suggests that the Scot tish and Brittany scallop populations are, nevertheless, genetically d istinct.