Réponses des peuplements et populations de poissons aux réserves marines: le cas de l'île de Mayotte, Océan Indien occidental

This study investigates the effects of establishment of a marine reserve on the coral reef fish communities at Mayotte Island, Western Indian Ocean, after three years of protection. Both total species richness and global abundance did not differ significantly between protected and non-protected areas. Nevertheless, there were significant differences for numerous families and species. Most of the big carnivorous fishes (Serranidae, Lutjanidae, Lethrinidae) were more diverse and more abundant in the marine reserve. Conversely, other fishes, mainly in the families Pomacentridae, Scaridae and Acanthuridae, presented the opposite pattern. The mean biomass of commercial fish species was significantly higher in the reserve (202 g.m^-2) than in non-protected areas (79 g.m^-2). This pattern was also evident for carnivorous fishes, such as Epinephelus microdon, and semi-pelagic fishes, such as Caesionidae. In contrast, other commercial species, such as Scarus caudovittatus and Acanthurus nigricauda had higher biomass in non-protected areas. Despite this apparent contradiction, our results seem to be linked with the marine reserve protection. Cessation of fishing activities in the reserve may have caused increases in diversity, abundance and biomass of large carnivores. The decrease in the number of these fishes in non-protected areas due to fishing may favour development of other populations, dominated by potential prey for carnivorous fishes.