THE EFFECTS OF FISHING ON THE DIVERSITY, BIOMASS AND TROPHIC STRUCTURE OF SEYCHELLES REEF FISH COMMUNITIES

A fishery independent underwater visual census technique was used to a ssess the effects of fishing on the diversity, biomass and trophic str ucture of the diurnally active non-cryptic reef-associated fish commun ities of the Seychelles. One hundred and thirty four species associate d with three significantly different types of reef habitat were census ed at one unfished ground and in six fishing grounds subject to differ ent fishing intensities. There was an inverse relationship between fis hing intensity and the biomass of several species targeted by the fish ery. The diversity of families containing target species (lutjanidae, lethrinidae) was significantly higher at unfished and lightly fished s ites as was the total biomass of the fish community and the biomass of piscivorous, piscivorous/invertebrate feeding and herbivorous trophic groups. However, there was no indication that the biomass of non-targ et species increased in response to the removal of their predators by fishing. The findings of this study are significant for fishery manage rs because they suggest that the intensive differential cropping of to p predators will not necessarily lead to increases in the biomass and productivity of their prey.