British Columbia

Climate change to bring great white sharks to B.C. says UBC prof

Great white sharks are only rarely seen in B.C.'s chilly waters now, but that's expected to change under a warming climate, says a UBC fisheries researcher.

Computer models suggest today's rare sightings could become regular occurrences with warming waters

A great white shark swims past a diving cage near South Africa in this undated file photo. (Reuters)

As if climate change isn't already scary enough, here's a new reason to curb emissions.

Great white sharks are likely to move north as B.C.'s chilly Pacific waters warm, said associate professor William Cheung of UBC's Institute for the Oceans and Fisheries.

His team has been developing computer simulation models on how fish distributions will change in the future and finds temperature changes are likely to expand the range where sharks regularly live.

"For many of the fish, as well as shark species, including great white, the distribution will shift with ocean warming," said Cheung.

"Species will be able to expand their range to an area where before it may be too cold for them to live."

Great white sharks can already be spotted on the B.C. coast but such sightings are rare — with only 14 records over 43 years, according to the Committee on the Status of Endangered Wildlife in Canada.

The giant fish are also found in Atlantic Canada and are considered endangered there with 32 sightings over 132 years.

Great white sharks, though notorious in popular culture, are actually considered vulnerable worldwide, due to overfishing, habitat degradation and other threats. (Shutterstock)

California in Canada?

While there's uncertainty around how quickly oceans will warm, Cheung said under a "business-as-usual-scenario," without drastic cuts to emissions, waters off B.C. are forecast to be about 1.5 C warmer than today by the year 2050.

That's expected to bring more species to Canadian waters that are common, say, in California now, said Cheung.

"Although people [think of] them as dangerous ... in fact they are very important for the health of the ecosystems as the top predators.- UBC professor William Cheung on great white sharks

But in ecology, it's never that simple.

Temperature is important, but there are other factors that determine where a species can survive — including what there is to eat, or be eaten by, and who else is competing for food and shelter — and climate change will disrupt those interactions too.

"It's quite difficult to predict how the ecosystems will change because of this new relationship between prey and their predators," said Cheung.

"That's why we see climate change is posing additional risk and uncertainty to ecosystems."

Great whites, which are officially listed as "vulnerable" worldwide, are also threatened by overfishing, habitat loss and other issues, according to the International Union for Conservation of Nature.

"Although people [think of] them as dangerous, in some cases because of the movies ... in fact, they are very important for the health of the ecosystems as the top predators," said Cheung.