In the coming decades, warming ocean temperatures could stunt the growth of fish by as much as 30 percent, according to a new study in the journal Global Change Biology.
The main driver behind this decline in size is that warmer water contains less oxygen. As Nexus Media explains, fish are cold-blooded animals and therefore cannot regulate their own body temperatures. So as oceans heat up, a fish’s metabolism accelerates to cope with the rising temperatures and they need more oxygen to sustain their body functions. But fish gills do not grow at the same pace as the rest of their body, resulting in a decline of oxygen supply and in growth.