Amid signs that the North Atlantic’s great white shark population is growing, popular Cape Cod beaches are using technology to warn swimmers and surfers when it’s time to get out of the water.
And while Nova Scotia is only 265 nautical miles away from Boston, as the shark swims, beachgoers in Canada’s ocean playground have no such protections.
“We are able to detect tagged sharks — sharks that are carrying acoustic transmitters — and those transmitters are emitting a very high frequency sound that’s detected by an array of acoustic receivers that we have set up around some of the more popular swimming beaches,” said Greg Skomal, a senior fisheries biologist with the Massachusetts division of marine fisheries and director of the state’s shark research program.
“Any time one of those tagged sharks is detected by one of those receivers, it issues a notification through cell phone to the respective public safety officials for that beach.”
Lifeguards get immediate warnings about the shark’s nearby presence, he said. They could then put up flags, close the beach for an hour, or use other methods to pull people out of the water, Skomal said, noting anyone using Cape Cod’s beaches can get the same white shark warnings sent straight to their phone through the free app called sharktivity.
“We think it’s a great warning system, but more so, really, an educational system for the public safety officials because we have to fully acknowledge that not all the sharks are tagged,” Skomal said in an interview from Tortola, in the British Virgin Islands, where he has been tagging sharks in recent weeks.
“We don’t want people to have this false sense of security if they’re not getting a notification.”
Cape Cod — where scientists see a high density of white sharks — has seen three incidents of sharks biting humans since 2012, one of which was fatal in September 2018.
“We’ve (also) had a couple of incidents where a paddle board or a kayak was bitten, but the individual was not,” Skomal said.
Nova Scotia saw a white shark bite a young woman who jumped off a boat near Cape Breton’s Margaree Island in August of 2021. A duck hunter also lost his dog to a shark bite off Port Medway in 2023.
“Nova Scotia is interesting; it has lots of white sharks visiting,” said Skomal, who has tagged sharks in waters around the province.
“We just published a paper that shows the increase in the number of white sharks visiting Nova Scotia and Canada over the last ten years,” he said. “It’s at least a two-fold increase.”
Scientists believe the white shark population is rebounding due to conservation measures that reduced the number of them killed as bycatch in other fisheries, and an abundance of grey seals — their favourite prey — now that people no longer hunt them.
There are acoustic receivers throughout Canadian waters, including “the entire Bay of Fundy” and all the way up to the Gulf of St. Lawrence and Newfoundland, Skomal said.
The organization Ocearch has a free tracking app that shows users where white sharks have surfaced recently. But that doesn’t offer real-time warnings.
“If people are worried about a particular beach, just do a little homework,” Skomal said. “See if there’s been white shark detections in the area. Know your own strengths and weaknesses in the water. Look for seals — that’s a sign of white shark activity — or could be.”
Should Nova Scotia be following suit and setting up shark warning systems that could deliver immediate notice of a tagged shark’s presence, like the ones on Cape Cod?
“It’s certainly something to consider,” Skomal said. “You guys need to understand where those hotspots are.”
But Fred Whoriskey, an adjunct marine biology professor at Dalhousie University and the former head of Canada’s Ocean Tracking Network, doesn’t think Nova Scotia’s beaches need real-time shark warning systems.
“We haven’t perceived a need yet,” Whoriskey said in a telephone interview from Traverse City, Michigan, where he’s attending a conference on fish telemetry.
“We have no indication the sharks are concentrating around the beaches in the same way that they do in Cape Cod. The big difference that you have down there is on Cape Cod you have a colony of better than 10,000 seals that have set themselves up in the prime beach areas — the swimming areas for the tourists — and that’s what’s attracted the sharks into those particular zones.”
While seals occasionally make their way to Nova Scotia beaches, they tend to prefer isolated offshore islands, he said.
“If they haven’t got food, the sharks don’t concentrate there,” Whoriskey said.
About 800 white sharks have cruised through the Cape Cod area over the past four years, he said.
“We know that we’ve been detecting at least 100 tagged white sharks crossing through Nova Scotia waters on kind of an annual basis,” Whoriskey said. “We’re assuming that there are probably more than that out there, but how many more, it’s purely speculative at this point in time.”
The live detection systems that listen for tagged sharks are expensive, Whoriskey said. “It’s $10,000-20,000 a year per live buoy to maintain it,” he said, noting one can detect tagged sharks a kilometre away.
Nova Scotia should consider live shark monitoring for its beaches, said Nigel Hussey, an associate professor of biology at the University of Windsor.
There’s “a very small chance” someone will get bitten by a shark at one of the province’s beaches, Hussey said in a telephone interview from Big Tancook Island, in Nova Scotia’s Mahone Bay, where he’s in the process of setting up a shark research station.
Live shark warnings would minimize the potential for “that very tiny risk of a human-shark conflict,” he said.
“Often the nature of public spending and government spending is they don’t react until something happens,” Hussey said.
“But perhaps what happened in Cape Cod sets a good example where they learned that lesson that Nova Scotia could take on board…. We should be proactive in terms of what we’re doing.”
Nova Scotia installed shark warning signs at about a dozen beaches last summer.
“There really has never been a shark attack on any of our beaches,” said Paul D’Eon, who heads the Nova Scotia Lifeguard Service.
Still, he’s interested in learning more about real-time shark warnings.
“Is it going to save lives?” D’Eon said. “Certainly, we would look at that.”
However, he stressed the likelihood of a shark attack at one of the province’s 23 guarded ocean beaches is unlikely. “Way more people are killed on their way driving to the beach than while at the beach,” D’Eon said. “The numbers are extremely remote as to the risk of being attacked by a shark in Nova Scotia at this point.”
His first summer as a lifeguard was 1975, the year Jaws came out.
“I experienced first-hand the paranoia,” D’Eon said. “People wouldn’t go up to their knees (in the ocean) for fear of being attacked by sharks. And it’s ongoing — every summer in mid-swimming season, what comes on (the Discovery Channel)? Shark Week — and people get more terrified.”
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