“If you’re worried about marine life off the west coast of North America, you’re worried about anchovies and other forage fish in the California Current. Ultimately it’s what underpins the food web,” says lead author Evan Howard, a postdoctoral researcher in oceanography at the University of Washington.

Climate change and ocean breathability

The study shows that species respond to how breathable the water is—a combination of the oxygen levels in the water and the species’ oxygen needs, which water temperature affects.

The anchovy historical data matches this pattern, and suggests that the southern part of their range could become uninhabitable by 2100.

“Climate change isn’t just warming the oceans—it is causing oxygen to decrease, which could force fish and other ocean animals to move away from their normal range to find higher-oxygen waters,” Howard says.