MEDITERRANEAN MARINE RESERVES - FISH INDEXES AS TESTS OF PROTECTION EFFICIENCY

The fish assemblages of a strictly protected area and of a neighbourin g fished area, located off a Mediterranean urbanized coast (Carry-le-R ouet, France), were compared in order to select the most evident, cons tant, and easily recorded indices of the 'reserve effect'. Visual cens using was repeated simultaneously at both sites eight time a year duri ng 3 years along four permanent transects layed on shallow rocky botto ms (9-14 m). Overall species richness was 16% higher in the reserve, b ut differences in average instantaneous richness were only marginally significant. The most contrasting results were shown by the occurrence frequency, abundance, and demographic structure of two types of targe t species. The type A target species group comprises 16 large meso- an d macrocarnivores particularly threatened by spearfishing, including t he common nectobenthic sparids Diplodus spp. Type B target species are represented by two small territorial fishes particularly impacted by angling: the serranid Serranus cabrilla and the terminal phase males o f the labrid Coris julis. The size structure of Diplodus spp., S. cabr illa, and C. julis subpopulations strongly argues for the role of prot ected areas as a reservoir of large spawners. Fishing pressure is assu med to modify the social conditions of the C. julis local populations and to induce earlier sex change.