FISH in large numbers are migrating towards the north polar regions at an increasingly rapid rate, warns a study from Canada’s University of British Columbia.
The research has shown they are moving poleward at a speed of 26 kilometres each decade. The University’s results bear out what has been found by researchers in Norway and Iceland – that sea warming is driving popular species like cod and haddock further north. In fact as far back as the 1970s British fishermen were finding that warm water species normally found much further south were appearing in the North Sea in increasing numbers, suggesting that the sea was becoming warmer.
The University of British Columbia study has identified ocean hotspots for local fish extinction but also found that changing temperatures will drive more fish into the Arctic and Antarctic waters.
Using the same climate change scenarios as the Intergovernmental Panel on Climate Change, researchers projected a large-scale shift of marine fish and invertebrates. In the worst-case scenario, where the Earth’s oceans warm by three degrees Celsius by 2100, fish could move away from their current habitats at a rate of 26 kilometres per decade. Under the best-case scenario, where the Earth ocean warms by one degree Celsius, fish would move 15 kilometres every decade. This is consistent with changes in the last few decades.
“The tropics will be the overall losers,” says William Cheung, associate professor at the UBC Fisheries Centre and co-author of this study, published today in ICES Journal of Marine Science. “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.”
Cheung and his colleague used modelling to predict how 802 commercially important species of fish and invertebrates react to warming water temperatures, other changing ocean properties, and new habitats opening up at the poles.
“As fish move to cooler waters, this generates new opportunities for fisheries in the Arctic,” says Miranda Jones, a UNBC Nereus Fellow and lead author of this study. “On the other hand it means it could disrupt the species that live there now and increase competition for resources.”