Interações sociais, uso do habitat e estrutura populacional do tubarão-limão , negaprion brevirostris (Poey, 1868), no arquipélago de Fernando de Noronha (PE).

Abstract

The population structure and habitat use of Negaprion brevirostris were verified through five expeditions to Fernando de Noronha archipelago. To achieve this we used three different methodologies: active search, strip transects and terrestrial observations from an elevated point. The age structure configuration revealed that young sharks are predominant, followed by subadults, adults and neonates. The sex ratio was strongly female skewed, what suggest sexual segregation. Neonates were frequently observed in groups and always at 1.5 m maximum depth. An analysis of covariance (ANCOVA) was performed and we verified that shark’s sightings were correlated to site, temperature and depth. In general, young and subadults sharks preferred shallow and warmer waters, with an optimum temperature around 27 º C and depths of less than 6 m. The greatest number of shark’s sightings took place at Buraco da Raquel. Lemon sharks did not choose between rocky or sandy substrates but they avoided the harbor region, probably because the anthropogenic development. The presence of sharks in nearshore environments indicates their site attachment and, perhaps, predator avoidance. Sharks were mostly observed at non-human interference areas, what reveals the magnitude need for creation and implementation of marine protected areas.