Rising ocean temperatures are forcing fish to move to colder water or to dive deeper, scientists said on Wednesday.
Many species are moving from equatorial areas and higher water temperatures to find new homes closer to either the north or south poles, researchers found.
The University of Glasgow study raises questions about the knock-on effects that the move will have on species already living there.
“We observed a striking trend wherewith species living in areas that are warming faster are also showing the most rapid shifts in their geographical distributions,” said study lead author Carolin Dahms.
“It's possible that rate of warming in some regions may be too fast for fish to adapt, and so relocating may be their best coping strategy.
“At the same time we see that their ability to do so is also impacted by other factors such as fishing, with commercially exploited species moving more slowly.”
Prof Shaun Killen, senior author of the study, said: “While relocation to cooler water may allow these species to persist in the short term, it remains to be seen how food webs and ecosystems will be affected by these changes.
“If the prey of these species don't also move, or if these species become an invasive disturbance in their new location, there could be serious consequences down the road.”
For marine life, water temperatures affect critical functions, including metabolism, growth and reproduction, and they often have a very narrow temperature range within which they can live.
Researchers say that means marine-life changes caused by climate change have been happening up to seven times faster than animal responses on land.
The study found the majority of the world's fish population are shifting closer to the poles or deeper waters to stay cool.
It looked at data on 115 species of fish in all major ocean regions.
Climate change has had a substantial effect on marine ecosystems over the past century.
Some fish species have completely disappeared from some locations.
While in some cases some fish species may be able to change aspects of their biology to adapt to warmer conditions, a relocation may be the only means of coping with rapid increases in temperatures.
It is the first time such a comprehensive global analysis has been undertaken.