EFFECT OF A MARINE RESERVE ON THE DISTRIBUTION OF CORAL-REEF FISHES IN BARBADOS

High population densities of larger fish within reserves could result in emigration of fish to surrounding non-reserve areas, producing a gr adient of abundance and mean size across the reserve boundaries. The d ifference in fish abundance and size between reserve and non-reserve s hould be higher for sedentary than for mobile species and for highly c atchable than for less catchable species. To test these hypotheses we estimated the abundance and size of fishes by trapping and visual cens us on fringing reefs in Barbados: 5 reefs within the 2.2 km of the Bar bados Marine Reserve (BMR) and 8 reefs in the non-reserve (NR) area wi thin 4 km of the reserve boundaries. The abundance of large, trappable size fish of all species combined was higher in the BMR than in the N R, but abundance of small, nontrappable fish did not differ between BM R and NR. Trap catches decreased gradually with distance from the BMR center, but this gradient of abundance was less evident in visual cens us counts of trappable size fishes of all species combined, and not ap parent in trap or visual census estimates of abundance for individual species. Mean size was larger in the BMR than in the NR for 18 out of 24 species. The relative differences in both abundance and size betwee n BMR and NR did not differ between mobile and sedentary fish taxa. Ho wever, for sedentary taxa, the relative differences in abundance and s ize increased with trappability (the vulnerability to traps, which are the most common fishing method). These patterns suggest that the BMR does protect the fish community from fishing mortality and that emigra tion rates are generally low. Trappability and mobility depend on comp lex behavioral characteristics of fishes and are potentially important for the functioning of marine reserves.