Early growth and juvenile population structure of lemon sharks Negaprion brevirostris in the Atol das Rocas Biological Reserve, off north-east Brazil

Lemon sharks Negaprion brevirostris were sampled in the Atol das Rocas, a nursery area, on nine occasions from March 1999 to October 2003, during which 157 individuals were tagged and 35 were recaptured. The male : female sex ratio of captured individuals was 1 : 1.12. Mean +/- SD. growth rates were 24.7 +/- 3.4 cm year(-1) in total length (L-T), 20.7 +/- 3.2 cm year(-1) in fork length, and 19.5 +/- 2.7 cm year(-1) in precaudal length. There was no significant difference in growth rates between males and females. Mean +/- SD. increase in mass was 2565 +/- 762 g year(-1). The von Bertalanffy growth parameters estimated by the Fabens method based on L-T were: k = 0.077, L-infinity = 399.9 cm and t(0) = -2.16. Despite the large variation of environmental conditions, particularly of tidal range and currents, and the lack of protective mangrove cover in the nursery area at Atol das Rocas, juvenile lemon sharks grew relatively faster than at other nurseries. Such rapid growth could be a response to abundant food availability or high risk of predation by adults that enter the nursery area. (c) 2006 The Fisheries Society of the British Isles.