Montreal

Rise in basking shark sightings worries Sept-Îles swimmers—but no danger there, says researcher

If you saw a 10-metre-long shark nonchalantly circle your boat one hot summer day, Anik Boileau says she wouldn't blame you for feeling unnerved.

Warm water, more plankton could be behind increase in sightings this summer, says Anik Boileau

People in a small boat follow a giant basking shark swimming close to the surface of the water.
Several videos of basking shark sighting in the Gulf of the Saint Lawrence have popped in recent weeks, with a rise in sightings in the area. (Station de Recherche des Îles Mingan / Mingan Island Cetacean Study - MICS Facebook screenshot)

If you saw an eight-metre-long shark nonchalantly circle your boat one hot summer day, Anik Boileau says she wouldn't blame you for feeling unnerved. 

"They're quite big," said Boileau, the director of a marine research centre based in Sept-Îles. "But they're really, really not dangerous."

Basking sharks are the second largest shark species after whale sharks, but unlike many of their shark contemporaries, they're unafraid of humans and are unlikely to attack them, or any other fish for that matter.

They are slow-swimming, plankton-eating creatures that tend to catch the eye of a couple local residents every year.

This year, though, Boileau says they seem to be having a field trip in the Gulf of the Saint Lawrence. Already in the past month, she knows of six sightings, in addition to five videos from people who saw them in the gulf. 

The sightings have been met with concern by a number of residents and Boileau says she wants to reassure people that they can carry on with their water activities, unbothered. 

Echoes of JAWS

Some of those videos have eerily echoed the 1975 movie JAWS, with their depiction of a large shark fin gliding across the water.

It's not clear to Boileau whether the sightings feature different sharks or some of the same.

"There are of course more observations than usual," she said. But she's confident there aren't necessarily more than usual.

"Personally, I think it's because the water is much hotter this year in the area."

While the Atlantic sea's surface water in the Sept-Îles area will typically reach 10 C in the summer, she says it's now lept to 20 C. Sept-Îles is in the throes of a heatwave.

'A very mysterious shark'

For one, Boileau says, basking sharks — true to their name — like to bask in the warm sunlight. More plankton may also bloom in the heat, she said, causing them to rise to the surface to feed more. 

Boileau says the basking shark may be big, but little is known about its life history.

"It's a very mysterious shark," she said, adding it could be endangered, something the Canadian Department of Fisheries and Oceans is looking into.

With files from CBC reporter Valeria Cori-Manocchio