Fisheries mixed up by climate change

11 October 2009
Posted by Chris Smith.

Reef FishMore predictions have emerged of how climate change is likely to affect the planet. This time, scientists from the Sea Around Us project based at the University of British Colombia in Canada, have turned their attention to how the shifting climate could impact the world's fisheries. And as you might imagine, it is not good news.

Within the next 50 years, catches of fish in the tropics could drop by 40% because of the changing climate. However, in areas further north and south, fisheries could in fact expand by as much as 30 or even 70%.

William Cheung, Daniel Pauly and colleagues have run computer models of over a thousand marine species encompassing around 70% of the world's fisheries, ranging from krill to sharks, plugging in environmental and biological factors that affect their distribution.

The team then ran a simulation of how those factors are likely to change and hence how fish populations will respond under two different climate change scenarios - although not including the worst case scenario that the International Panel of Climate Change (IPCC) have put forward.

Under these models, certain countries will see fish disappearing from their nets, including Chile, China, the US and Indonesia. And that is simply because fish will not tolerate in higher temperatures.

Fish that can swim far enough, could potentially move to cooler waters in the north and south. This is why the models predict increased fish catches in some countries notably Russia, Norway, Greenland and Alaska.Black-spotted puffer fish, Arothron nigropunctatus

Fish that aren't able to swim far enough could go locally extinct as the climate changes.

For people living in poorer parts of the world who rely heavily on the sea for a source of food and income, this could spell disaster, especially given that other studies predict that climate change will lead to on-land food shortages in similar regions.

Published in the journal Global Change Biology, the results of this study are likely to be a conservative view of the changes that are due to come. The researchers did not, for example, consider how the increasing acidification of the oceans will affect fish distributions.

And of course, with predictions of the increasing collapse of fisheries due to overexploitation, the overall prognosis for the oceans is not a good one.

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