Retrospective stable isotopes of vertebrae reveal sexual ontogenetic patterns and trophic ecology in oceanic whitetip shark, Carcharhinus longimanus

There is a common phenomenon in nature whereby some animals have differences in their ontogenetic changes in dietary preferences between sexes, especially apex predators. These reflect changes in the needs of development during their lifetimes. Apex predators potentially have diverse dietary niches and a large impact on the trophic dynamics within ecosystems. However, the difference in life history between males and females often leads to increased difficulty in management and conservation. In this study, 25 oceanic whitetip sharks, Carcharhinus longimanus, were collected from the central and eastern tropical Pacific. Retrospective stable isotope analysis of vertebrae was used to evaluate the potential ontogenetic differences in feeding habits and niche width between sexes. Results showed that C. longimanus had a wide range of delta C-13 values (-18.1 to -12.3 parts per thousand) and delta N-15 values (8.9-14.8 parts per thousand). However, males and females had similar trophic positions with large niche overlap at similar growth stages. Both sexes had increasing delta C-13 values but relatively constant delta N-15 values along the vertebrae. These results indicated that male and female C. longimanus may share similar feeding strategies and movement patterns. The results presented in this study enhance our understanding of sexual ontogenetic patterns and ecological role of C. longimanus and highlighted the applicability of vertebrae for characterizing shark life-history traits.

Automated summary

The study showed that male and female oceanic whitetip sharks exhibit some differences in dietary habits and niche width, but have similar trophic positions and niche overlap at similar growth stages. This suggests that male and female C. longimanus may share similar feeding strategies and behavior patterns.