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Size frequency,dispersal distances and variable growth rates of young sharks in a multi-species aggregation
Authors:Ornella C. Weideli  Yannis P. Papastamatiou  Serge Planes
Affiliation:1. PSL Research University: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France;2. Department of Biological Sciences, Marine Sciences Program, Florida International University, North Miami, Florida, USA;3. PSL Research University: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France

Laboratoire d'excellence ‘CORAIL’, EPHE, PSL Research University, UPVD, CNRS, USR 3278 CRIOBE, Papetoai, Moorea, French Polynesia

Abstract:During a mark–recapture survey from November 2014 until April 2017, 333 neonatal and juvenile blacktip reef sharks Carcharhinus melanopterus and 302 neonatal and juvenile sicklefin lemon sharks Negaprion acutidens were tagged and measured at the uninhabited and isolated St. Joseph Atoll (Republic of Seychelles). Both species demonstrated seasonal reproductive synchronicity and relatively large sizes at birth. Despite the extended times at liberty > 2.5 years, the majority of recaptures were found in close proximity to the initial tagging location (< 500 m). Annual growth rates of C. melanopterus (n = 24) and N. acutidens (n = 62) ranged from 6.6 to 31.7 cm year−1 (mean ± SE; 16.2 ± 1.2 cm year−1) and 0.2 to 32.2 cm year−1 (11.8 ± 1 cm year−1), respectively and are to date the most variable ever recorded in wild juvenile sharks. High abundances of both species coupled with long-term and repeated recaptures are indicative of a habitat where juveniles can reside for their first years of life. However, large variability in annual growth rates in both species may suggest high intra and interspecific competition induced by a possibly resource limited, isolated habitat.
Keywords:annual growth  dispersal distances  Indian Ocean  juvenile sharks  neonatal size  resource limitation
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