Trophic ecology of common bottlenose dolphins in a pelagic insular environment inferred by stable isotopes

Abstract The common bottlenose dolphin ( Tursiops truncatus ) is a top marine predator widely dispersed in coastal and pelagic habitats with generalist feeding behavior. Yet, information on the trophic ecology of animals inhabiting environments still scarce. Using carbon (δ 13 C: C/ 12 C) nitrogen 15 N: N/ 14 N) stable isotope ratios, we identified quantified main groups prey assimilated by dolphins an oceanic habitat (Madeira Island, East Atlantic). Bottlenose pelagic, schooling fish (such as blue jack mackerel, Trachurus picturatus mesopelagic demersal squids, which reinforces dietary composition insular/oceanic dolphins. Also, intra-seasonal differences were found their suggest intraspecific variability behavior among individuals living same area. Sex was not factor contributing to these differences, suggesting lack niche segregation between adult males females this offshore environment. Nonetheless, further studies including different life stages ecophysiological requirements are necessary disclose factors responsible for observed variability. This study showed that insular fed primarily economically important prey, highlighting need developing management strategies integrate conservation fisheries plans.