Relocation of marine fish towards the poles is a response to ocean warming.

The majority of fish populations in the sea are responding to global warming by moving towards cooler waters near the North and South Poles, according to the latest research on the impact of climate change on our oceans.

Analyzing the breadth of current data around the world on marine fish changes in recent years, researchers from the University of Glasgow have revealed how fish populations across Earth’s oceans are responding to rising sea temperatures.

The latest study determined that in response to warming oceans, many marine fish populations are moving toward Earth’s poles or moving into deeper waters — all in an effort to stay cool.

For marine life such as fish, the ambient water temperature affects vital functions such as metabolism, growth, and reproduction. Furthermore, marine species often have a very narrow livable temperature range that makes even small differences in the water impossible to handle. As a result, changes in marine life caused by global warming have been seven times faster than the responses of animals on land.

Over the past century, global warming has had significant impacts on marine ecosystems, with fish species completely disappearing from some locations. In some cases, marine fish may be able to adapt and alter aspects of their biology in order to adapt to warmer conditions. However, in many cases, a change in geographic range may be the only means of dealing with rapid warming.

With the current impacts of global warming expected to increase on marine ecosystems – and with sea temperatures expected to continue to rise – our ability to predict fish transfer will be vital to protecting global ecosystems and maintaining food security.

This latest study examined data on 115 species covering all major ocean regions, with a total of 595 marine fish species responding to rising sea temperatures – the first time such a comprehensive global analysis has been undertaken.

Caroline Dhams, lead author on the study, said, “We observed a striking trend[where]species that live in areas that warm faster also show faster shifts in their geographic distributions.

“It is possible that the rate of warming in some areas is too rapid for fish to adapt, so relocation may be the best adaptation strategy. At the same time, we see that their ability to do this is also affected by other factors such as fishing, as exploited species move slower commercially.

Professor Sean Killeen, senior author of the study, said, “While the transition to colder waters 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 this species’ prey does not move as well, or if this species becomes an invasive disturbance in its new location, there could be serious consequences down the road.”

Furthermore, the study found that how these climate responses are measured and reported is also important. While the current literature is biased towards commercially important boreal species, in the future, more research from some of the more rapidly changing ecosystems such as in the Global South will be needed to improve our understanding of how our oceans are changing.

The paper, “Effects of temperature change on marine fish range shifts: a meta-analysis of ecological and methodological predictions” is published in The biology of global change.