Genetic variation and population structure in the marine snail Chorus giganteus (Gastropod: Muricidae), an overexploited endemic resource from Chile

The endemic marine gastropod Chorus giganteus represents a significant part of the benthic biomass subject to heavy exploitation by artisanal fisheries in Chile. Overexploitation has restricted its formerly wide distribution to few sites, and this study deals with the electrophoretic characterisation of three populations from the two main fishing grounds in the south coast of Chile (37–39°S). While frequency of polymorphic loci is high (41–50%), the observed heterozygosity is low (between 0.028 and 0.040) though within the range for molluscs. Heterogeneity in allelic frequencies at six polymorphic loci suggests potential for population substructuring. All these loci showed significant heterozygote deficits. The calculated number of migrants per generation ( N e m =4.75), based on a Wright’s F ST mean value of 0.05, accounts for low gene flow among populations in line with breeding behaviour (locally restricted). These preliminary results set a baseline for further evaluation of the intraspecific genetic diversity of an overexploited mollusc with low larval dispersal ability, and hence limited ability for colonisation. Since basic culture techniques are not yet available, genetic monitoring of this species throughout its entire distribution should be promoted for proper management and/or conservation of the species gene pool, in addition to current regulations aimed at restricting further exploitation.