Rising Ocean Temperatures Threaten Warm-Blooded Sharks and Tuna

A new study has revealed that larger warm-blooded fish, such as sharks and tuna, could struggle more as ocean temperatures rise. Published in Science, the research suggests these predators may find it harder to regulate their body heat in warming seas. A team from Portugal led the investigation by tracking species in the Azores. The study focuses on mesothermic fish—animals that keep their body temperature higher than the surrounding water. Unlike fully cold-blooded species, these predators retain heat, which helps them hunt and swim efficiently. But as oceans warm, their ability to cool down weakens, putting them at risk.

To monitor these changes, researchers tagged sharks in the Azores with two types of tracking devices. One records movements for up to a year, while the other measures temperature and depth. The team aims to determine how these fish will adapt to shifting conditions over time. The findings highlight a potential challenge for larger mesothermic species. Unlike smaller fish, they retain more heat, making them more vulnerable to rising temperatures. This could affect their survival and behaviour in the long term.

The research provides new insight into how warm-blooded predators may cope with climate change. By tracking their movements and body temperatures, scientists hope to predict future impacts on marine ecosystems. The study’s results will help inform conservation efforts for these key species.