Warm-bodied sharks and tunas face rising heat stress in warming seas
Bottom line
Warm-bodied sharks and tunas may be especially vulnerable as oceans warm, according to a new Science study led by Trinity College Dublin and the University of Pretoria. The researchers found that mesothermic fish, including tunas and some sharks, use about 3.8 times more energy than similarly sized cold-blooded fish, while also facing a growing risk of overheating as body size increases. The team says that creates a “double jeopardy”: these animals need more food to fuel their metabolism just as warming seas and ecosystem pressure may reduce suitable habitat and prey availability. The work was highlighted by Trinity College Dublin, EurekAlert, and other science outlets after publication on April 16, 2026. (tcd.ie)
Why it matters: For veterinary professionals, especially those working in aquatic animal medicine, conservation medicine, and wildlife health, the findings are a reminder that climate stress can show up as a physiology problem before it becomes a population crash. The study suggests larger warm-bodied predators may be forced into cooler, deeper, or higher-latitude waters as temperatures rise, potentially reshaping migration, prey interactions, bycatch risk, and rehabilitation or release considerations for species already under pressure from overfishing. NOAA has also documented that climate change and marine heatwaves are already shifting shark and tuna distributions, reinforcing the clinical and ecosystem relevance of thermal stress in marine species. (eurekalert.org)
What to watch: Watch for follow-up work on species-specific thermal thresholds, fishery management responses, and whether marine heatwaves accelerate range shifts in large sharks and tunas. (psl.noaa.gov)
A new Science paper is putting hard numbers on a growing marine health concern: warm-bodied sharks and tunas may be paying a steep physiological price for their evolutionary advantage. Researchers led by Trinity College Dublin, working with the University of Pretoria’s Faculty of Veterinary Science, reported that mesothermic fish burn roughly 3.8 times more energy than cold-blooded fish of similar size and temperature-adjusted comparisons, leaving them exposed to both rising metabolic demands and overheating risk in warming seas. (tcd.ie)
That matters because mesothermy has long been viewed as one reason species such as great white sharks, basking sharks, and tunas became such effective ocean predators. Retaining internally generated heat supports stronger muscle performance, sustained swimming, and wider foraging ranges. But the same adaptation may now be turning into a liability as ocean temperatures climb. Trinity and University of Pretoria researchers have been building this picture for several years, including earlier work showing that basking sharks are warm-bodied and that more shark species may use this strategy than once thought. (sciencedaily.com)
In the new study, the researchers combined temperature and heat-exchange data from wild fish, including large sharks, with broader comparative analyses to estimate metabolic costs and thermal limits. Their analysis found a mismatch between heat production and heat loss: as mesothermic fish get larger, they generate heat faster than they can shed it. EurekAlert’s summary of the paper said this creates an “overheating predicament,” which may help explain why these species are often concentrated in cooler, deeper, or higher-latitude waters. One example cited in coverage of the study is that a 1-tonne warm-bodied shark may struggle to maintain heat balance in waters above about 17°C without changing behavior or physiology. (eurekalert.org)
The research also points to limited coping options. Some species, including Atlantic bluefin tuna, can temporarily dump more heat or dive into cooler water, but the authors cautioned that these strategies may not hold up indefinitely if surface waters continue warming. At the same time, lead author Nicholas Payne noted in media coverage that these fish can’t simply increase food intake on demand, a key issue when overfishing and changing prey fields are already reducing ecological slack. That combination is what underpins the study’s “double jeopardy” framing. (tcd.ie)
Outside reaction has so far centered less on controversy than on the broader climate signal. NOAA Fisheries has previously reported that sharks and tunas respond unevenly but often substantially to marine heatwaves, with warming events redistributing top predators and shifting habitat use across regions. NOAA also notes that climate change is expected to alter shark distributions more broadly as animals track preferred ocean conditions. Taken together, that makes the new paper feel less like an isolated warning and more like a mechanistic explanation for changes marine scientists are already observing. (fisheries.noaa.gov)
Why it matters: For veterinary professionals, this is squarely in the lane of conservation medicine and aquatic animal health. Thermal stress affects behavior, energetics, immune resilience, habitat use, and survival, even when disease isn’t the immediate driver. Clinicians and researchers involved in stranded wildlife response, zoo and aquarium medicine, fisheries interactions, or species recovery may increasingly need to interpret cases through a climate-and-physiology lens, especially for large pelagic species. The work also underscores that population risk may be highest in animals that appear highly adapted and high-performing, because those traits come with unusually narrow energetic margins. (eurekalert.org)
There are also practical implications for fisheries and ecosystem management. If warm-bodied sharks and tunas are pushed poleward, deeper, or into narrower thermal windows, veterinary and wildlife teams may see knock-on effects in bycatch injury patterns, seasonal presence, prey stress, and rehabilitation decision-making. Species that are already conservation priorities could face overlapping pressures from warming, prey scarcity, and harvest. (fisheries.noaa.gov)
What to watch: The next phase will likely focus on species-by-species thresholds, links to marine heatwave forecasting, and whether managers incorporate thermal vulnerability more directly into conservation and fishery planning as ocean warming intensifies. (psl.noaa.gov)