Global warming to drive fish toward poles, study says

UBC researchers predict a large-scale shift of fish and marine invertebrates from the tropics toward Arctic and Antarctic waters because of rising temperatures.

Tropics 'overall losers' as marine life shifts to new habitats

Large numbers of fish will disappear from the tropics by 2050, according to a University of British Columbia study that examines the potential effects of climate change on marine life.

Researchers used the same climate change scenarios as the UN’s Intergovernmental Panel on Climate Change to project a large-scale movement of marine fish and invertebrates. They concluded that changing temperatures will drive more fish toward Arctic and Antarctic waters.

The UBC team came up with a worst-case scenario, in which the Earth’s oceans warm by three degrees Celsius by 2100. In that case, fish could move away from their current habitats at a rate of 26 kilometres per decade. Under the best-case scenario, where the Earth warms by one degree Celsius, fish would move 15 kilometres every decade.

William Cheung, co-author of the study released Friday, said the tropics would be the “overall losers” because countries in these regions rely heavily on fish for food.

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,” co-author Miranda Jones said in a release. “On the other hand, it means it could disrupt the species that live there now and increase competition for resources.”

Some of the fish stocks may adapt well to their new habitat, but some may not, Cheung told CBC News. He said for those that cannot, it may be because of the absence of specific spawning grounds or food items, or the occurrence of new predators.

The study was published in the ICES Journal of Marine Science (International Council for the Exploration of the Sea) and follows previous research out of UBC that looked at how warming ocean temperatures are driving species toward cooler, deeper waters.

That study, appearing May 2013 in the journal Nature, said climate change has been affecting global fisheries for the past four decades, with "serious implications for food security" in the tropics.