Sharks under pressure: Deoxygenating deep-sea drives sharks to the surface

Climate-driven ocean deoxygenation renders the ocean’s most wide-ranging shark more vulnerable to fishing

Research carried out by scientists at the Marine Biological Association (MBA) and institutes in Portugal and Spain, is the first to test whether expanding oxygen minimum zones (OMZs) in the oceans push sharks closer to the surface, making them more susceptible to capture by fisheries.

Climate-driven changes in the ocean are leading to reduced amounts of dissolved oxygen in seawater, known as ocean deoxygenation. It causes permanent OMZs that exist across the oceans, typically at depths of around 200-800 metres, to expand both horizontally and vertically. Ocean deoxygenation is likely to have important effects on large, high-oxygen demand fish such as pelagic sharks.