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Resumen del producto

Tamburin, E., F.R., Elorriaga-Verplancken, C., Estupiñán-Montaño, D.J., Madigan, A., Sánchez-González, M., Hoyos-Padilla, M., Wcisel & F., Galván-Magaña (2020). New insights into the trophic ecology of young white sharks (Carcharodon carcharias) in Baja California waters, Mexico. Northeast Pacific Shark Symposium IV. La Pa, Baja California Sur, México, marzo 5 - 7, 2020, 1.

New insights into the trophic ecology of young white sharks (Carcharodon carcharias) in Baja California waters, Mexico

Elena Tamburin, Fernando R. Elorriaga-Verplancken, Colombo Estupiñán-Montaño, Daniel J. Madigan, Alberto Sánchez-González, Mauricio Hoyos-Padilla, Michelle Wcisel y Felipe Galván-Magaña

White sharks are usually defined as generalist predators, with a well described ontogenetic dietary shift that occurs between the subadult and adult stages. Yet the majority of published studies have focused on large and mature individuals, so the information about feeding habits is still lacking for young white sharks. It is imperative to improve information about the trophic ecology of white sharks across life-stages to better understand habitat shifts and their early life movements inside nursery areas, which are determined by resources availability. This study provides the first insight into the trophic ecology of young white sharks using stable isotopes analysis (SIA) in muscle tissues to characterize prey contributions and ontogenetic changes in habitat use. We collected muscle of white sharks (n=21) from Sebastian Vizcaino Bay (SBV) during 2015-2018, including five newborns, three YOY and three juveniles. White shark isotopic values did not varyby sex (d15N values: W = 52, p = 0.8 and d13C values: t = 0.25, p = 0.8) as well as age classes (d15N values: W =54, p = 0.4 and d13C values: t = -0.9, p = 0.4) and we did not find variation based on size classes for d13C and d15N. However, we found changes in prey composition across white shark life stages, with significant changes throughout ontogeny. Mixing model indicate a high use of coastal areas for foraging, which likely represents the shift from the embryo’s typical maternally-derived isotopic signature incorporated in offshore foraging regions to the postpartum isotopic composition, incorporated by neonates from inshore nursery habitats, including SBV. This study reinforces the assertion that coastal areas, like SVB and the prey preferences that take place in this area (from previous research) are critical for the development and to the successful foraging of young white sharks, providing relevant knowledge regarding this species.

Palabras clave: white shark; Trophic ecology; Carcharodon carcharias

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