Climate change is driving fish away from oxygen-poor regions of the ocean. And the oxygen-poor regions are growing.
At the same time that oceans are taking in massive amounts of carbon dioxide, they're absorbing less oxygen than ever.
The top levels of the ocean are warmer than usual thanks to human-caused climate change. That is leading to an expansion of oxygen-poor hypoxic zones. Fish don't live in those. Large fish, in particular, are threatened by ocean oxygen loss, with the Pacific and Arctic experiencing the steepest declines.