New data on abundance of lemon shark Negaprion brevirostris (Poey, 1868) at Lama Bay, Rocas Atoll, Brazil

Abstract

The abundance and movement patterns of lemon sharks ( Negaprion brevirostris) at Lama Bay, Biological Reserve Rocas Atoll, were reassessed by visual census. We considered tides and daylight periods to plan our observations during two expeditions in 2015. Using daily visual counts, the mean abundance of individuals was 29 in austral summer (maximum 35) and 31 in winter (maximum 41). The results indicated that the local lemon shark population might have recovered after 18 years of a substantial drop in mean abundance. In addition, the movement pattern of the species corroborated previous studies related to their fidelity to the birthplace. These results justify the need of continuous monitoring of lemon sharks over the course of time at Rocas Atoll using non-lethal and non-invasive techniques.

Keywords
Conservation; Population ecology; Marine protected area; Visual census; Endangered