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September 17, 2019

Same species, different prerequisites: investigating body condition and foraging success in young reef sharks between an atoll and an island system

Publisher: Scientific Reports

Funders: ARC Centre of Excellence for Coral Reef Studies, Australian Research Council (ARC) Early Career Discovery Fellowship, Basler Stiftung für biologische Forschung, James Cook University Graduate Fellowship, L'Oréal-UNESCO Women in Science Foundation Fellowship, Save Our Seas Foundation (SOSF Keystone Grant 290)

Authors: Gauthie Mescam, Ian A. Bouyoucos, Jodie L. Rummer, Ornella C. Weideli, Serge Planes, Yannis P. Papastamatiou

Language: English

Acquiring and storing energy is vital to sharks of all age-classes. Viviparous shark embryos receive endogenous maternal energy reserves to sustain the first weeks after birth. Then, in order to maintain body condition, sharks must start foraging. Our goal was to understand whether maternal energy investments vary between blacktip reef sharks (Carcharhinus melanopterus) from two populations and to what extent body condition and the initiation of foraging might be affected by presumably variable maternal investments. A total of 546 young sharks were captured at St. Joseph atoll (Seychelles) and Moorea (French Polynesia) between 2014 and 2018, and indices of body condition and percentage of stomachs containing prey were measured. Maternal investment was found to be site-specific, with significantly larger, heavier, and better conditioned individuals in Moorea. Despite these advantages, as time progressed, Moorea sharks exhibited significant decreases in body condition and were slower to initiate foraging. We suggest that the young sharks' foraging success is independent of the quality of maternal energy resources, and that other factors, such as prey availability, prey quality, and/or anthropogenic stressors are likely responsible for the observed differences across sites. Insights into intraspecific variations in early life-stages may further support site-specific management strategies for young sharks from nearshore habitats.