Amid record-breaking high temperatures in Atlantic waters, marine life along the coast is having to adapt.
Among the changes, some species are moving north — including sharks.
“We’re teaching a shark class at Dalhousie and last year they saw their first tiger shark just off Halifax, which is a tropical species that we don’t normally expect here,” said marine conservation professor Boris Worm.
Worm says some species of sharks and other tropical and sub-tropical marine life are coming into Atlantic Canada waters more regularly.
“Although sharks are pretty slow to adapt to changing conditions, we do expect them to move northwards in some numbers,” Worm said.
These changes in distribution are being noticed across the East Coast, as there’s been more shark sightings reported as well as a white shark stranding on a Prince Edward Island beach.
“Overall, the question really that has been sitting on people’s minds: are we just seeing more sharks or hearing about more sharks or are there actually more sharks?” asked Marine Animal Response Society (MARS) executive director Tonya Wimmer.
Her team at MARS has had a busy few months of working to rescue beached marine animals.
“We anticipate seeing different species and a different distribution of the species in our waters, and it’s something we definitely have to keep track of in order to really see the full effects of climate change,” said Wimmer.
Dalhousie University Ocean Tracking Network Executive Director Fred Whoriskey believes we’re on “the cusp of an unprecedented change.”
“In the case of white sharks, I think the population is actually growing,” he continued.
An endangered species, there has been 20 years worth of protective efforts put into growing the white shark population — and we may now be seeing the very slow process of recovery.
“They’re reoccupying areas of Canada that were kind of abandoned,” said Whoriskey. “Because when populations declined they didn’t need to move up here to find the food that they needed in the winter. So some of that is going on as well.”
White shark populations likely began to decline due to getting stuck on fishing lines meant for other animals, like swordfish.
Paired with a slow reproductive rate and a long maturing timeframe makes population recovery slow, but a large seal population has allowed for a boost in food resources.
“It brings a smile to my face when we’re sitting back and talking about the ocean restoring itself,” Whoriskey said. “Because anything that’s restoring itself is probably a good sign, so nature right now obviously wants to have these animals there.”
Whoriskey cites research out of Massachusetts that shows a minimum of 800 white sharks are heading through Cape Cod on an ongoing basis, many of which are young.
“Of the sharks that pass through Cape Cod, about 30 per cent will stay there all summer and patrol the areas and look for the seals down there, but 70 per cent move off and they move north.”
He says a lot of those sharks are then cropping up in Canadian waters, where they are being detected on research equipment.
“It would perhaps not be unanticipated to begin to find sharks dying of other natural causes and maybe washing up on the beach,” Whoriskey theorizes regarding the recent shark sightings in the region.
According to these researchers, these changes in water temperatures and the species that inhabit Atlantic waters will have to come with human adjustments.
“Our management of our waters is geared towards a certain set of species that we expect to be here,” said Worm. “As that set of species is changing and environmental conditions are shifting, we have to adapt as well.”
Whoriskey adds that, “the ocean is changing so fast, mostly due to the big forcing functions that we have imposed on it like climate warming that’s happening right now. We’re just going to have to ride this one and see where we go.”
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