Powering ocean giants: the energetics of shark and ray megafauna

Shark and ray megafauna have crucial roles as top predators in many marine ecosystems, but are currently among the most threatened vertebrates and, based on historical extinctions, may be highly susceptible to future environmental perturbations. However, our understanding of their energetics lags behind that of other taxa. Such knowledge is required to answer important ecological questions and predict their responses to ocean warming, which may be limited by expanding ocean deoxygenation and declining prey availability. To develop bioenergetics models for shark and ray megafauna, incremental improvements in respirometry systems are useful but unlikely to accommodate the largest species. Advances in biologging tools and modelling could help answer the most pressing ecological questions about these iconic species.