Fish will flee the tropics if ocean temperatures warm

The extinction of polar bears, hurricanes hitting Manhattan, East Anglia disappearing under the North Sea – these are just some of the terrible predictions of what global warming might have in store for humanity.

And now a new study has raised another serious problem. And it’s all to do with fish.

What about the fish?

Huge numbers of fish species are predicted to leave the world’s tropical oceans by 2050 as temperatures rise.

At the same time, fish populations will also move into warming Arctic and Antarctic waters.

This will cause huge problems for local populations who rely on fish for their livelihood – be it to sell as food or entice tourists into their waters.

How bad is it going to get?

In the very best-case scenario, the Earth will only warm by one degree Celsius by the year 2100. This would see fish moving 15 kilometres north or south every decade.

But in the worst-case scenario the oceans will warm by three degrees Celsius by the end of the century. If this happened, fish could move away from their current habitats at a rate of 26 kilometres per decade.

Certain places were also picked out as hotspots for local fish extinction. People in these areas would be hit particularly hard.

How did they reach these figures?

The study – which was carried out by the University of British Columbia (UBC) – used the same climate change scenarios as the Intergovernmental Panel On Climate Change.

They also pointed out that their figures were consistent with what has already been happening over the last few decades.

The UBC team used modelling to predict how 802 commercially-important species of fish and invertebrates would react to warming water temperatures, as well as other changing ocean properties and the prospect of new habitats opening up for them at the poles.

Winners and losers

William Cheung, associate professor at the UBC Fisheries Centre and co-author of the study, said: “The tropics will be the overall losers.

“This area has a high dependence on fish for food, diet and nutrition.

“We’ll see a loss of fish populations that are important to the fisheries and communities in these regions.”

Miranda Jones, a UBC Nereus Fellow and lead author of the study, said the movement could generate new opportunities for fisheries in the Arctic.

But she added: ”On the other hand it means it could disrupt the species that live there now and increase competition for resources.”

The findings are published in ICES Journal of Marine Science.

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