EVIDENCE OF DIFFERENTIATED STOCKS OF ACANTHURUS-TRIOSTEGUS (PISCES, ACANTHURIDAE) IN FRENCH-POLYNESIA, USING ELECTROPHORETIC DATA

The degree of genetic differentiation between samples of convict surge onfish (Acanthurus triostegus), collected in the five archipelagos of French Polynesia, was estimated from electrophoretic data. Variant all eles at ten loci were detected and used to determine heterogeneity bet ween samples. Strong variation in the allelic frequencies was observed in eight loci. Analyses of the Nei's genetic distances calculated in all the polymorphic and monomorphic loci (31), which ranged from 0.001 7 to 0.0563, have shown three levels of differentiation, corresponding to the Marquesas Archipelago, the Tuamotu and Gambier Archipelagos an d the Society and Austral Archipelagos. Correlation between Nei's gene tic distances and geographic distances was very low, confirming hetero geneity between the different stocks. Analyses of individual probabili ties, calculated from the allelic combinations, have shown the existen ce of characteristic allelic combinations in each population. Genetic differences observed in A. triostegus populations in French Polynesia support the existence of different stocks spatially localized and main tained by restricted dispersal during the oceanic larval phase. This c onclusion suggests that the current fisheries management strategy, con sisting of no-management on the assumption that oceanic larvae from th e unoccupied islands can maintain stocks despite overfishing, is not a ppropriate for the A. triostegus situation.