Warm-Blooded Sharks and Tuna Face Ocean Heat Crisis

New research finds that warm-bodied marine predators, including great white sharks and tuna, burn nearly four times more energy than cold-blooded species, a metabolic premium that becomes increasingly costly as ocean temperatures rise. Unlike cold-blooded fish that passively match ambient water temperature, these species generate internal heat to sustain speed and predatory performance, but that same physiology limits their ability to shed excess warmth. As sea temperatures climb, the gap between their internal heat load and safe operating thresholds narrows sharply. The compounding problem is nutritional: warmer oceans are disrupting prey availability, meaning these predators must eat more precisely when food is harder to find. Researchers frame this as a 'double jeopardy' dynamic, where thermal stress and caloric shortfall reinforce each other. Population-level consequences for apex predators would ripple through marine food webs, with downstream effects on commercial fisheries and the broader ocean ecosystems that underpin them. Migration range compression is a plausible near-term stress signal to monitor.