The fear and interest in great white sharks was amplified among Cape Cod residents when “Jaws” came out in 1975. More recently, great white sharks have been coming to the Cape seasonally to hunt seals.
The Massachusetts Division of Marine Fisheries has been studying the migration of sharks for more than a decade. In 2019, it started a research plan to get a sense of white shark feeding behavior.
“We believe that if we know very effectively where, when and how white sharks feed on their natural prey, which are gray seals, we’d be able to identify those areas and those places and those times when people might be more at risk,” senior fisheries scientist Gregory Skomal said during a presentation to the Barnstable County Assembly of Delegates on Wednesday, November 18.
Dr. Skomal said white sharks are approaching close to the shoreline because they feed on seals, not because they want to eat or bite humans.
“A lot of our focus as marine biologists studying great white sharks has shifted away from some of the broad-scale aspects of natural history and movement to fine-scale patterns that will help us produce information that’ll be useful for beach managers and public safety officials,” he said.
As part of that pattern research, Dr. Skomal put six live receiver buoys in the water this summer to detect nearby tagged sharks in real time and to send notifications to public safety officials.
The objective is public safety, Dr. Skomal said.
“We’re all aware of the growing seal population on Cape Cod, that is throughout all of New England and into Canada,” Dr. Skomal said.
Dr. Skomal specifically mentioned gray seals, or Halichoerus grypus, which have been a protected population for 46 years.
“We now have something along the lines of about half a million seals in the North Western Atlantic, with tens of thousands occurring off Cape Cod,” he said. “As a result, we have drawn the attention of the number-one seal predator in the Atlantic Ocean—white sharks.”
The robust seal population draws the carnivorous white sharks, which Dr. Skomal said are well-adapted for attacking, killing and feeding on seals.
“White sharks are not only coming to New England in greater numbers, but they’re coming closer to shore and they’re hunting in very shallow water,” Dr. Skomal said. “On average, they spend almost 50 percent of their time in water that is less than 15 feet deep.”
And those white sharks are occasionally encountering humans in the water.
“We’ve had some negative interactions over the last several years,” Dr. Skomal said.
The most recent fatal attack on the Cape was in 2018, when Arthur Medici, 26, was attacked by a white shark and died from his injuries at Newcomb Hollow Beach in Wellfleet.
“Our last fatal attack prior to 2018 was in 1936 in Buzzards Bay off the coast of Mattapoisett,” Dr. Skomal said.
A human-shark interaction is still fairly rare, considering the number of people and the number of sharks in the waters off the Cape, Dr. Skomal said.
“If they were here to bite people, we’d have a lot more bites and, thankfully, we do not,” he said.
With the goal of public safety in mind, Dr. Skomal’s research has focused on white shark feeding patterns.
The sharks are tracked mainly through tagging. Dr. Skomal said the scientists do not chum for sharks or capture, bait or handle them in any way.
“Our goal when we are tagging is to be as minimally intrusive as possible because the one thing we don’t want to do is alter the behavior of the sharks, particularly in close proximity to where people are recreating along our beaches,” Dr. Skomal said.
To locate the sharks for tagging, the scientists use a spotter plane and then a long pole on the bow of a boat to place the tag through a small dart at the base of the dorsal fin while the shark is swimming.
The scientists have tagged and are tracking more than 200 white sharks. Those tagged sharks are integrated with the Atlantic White Shark Conservancy’s application “Sharktivity,” so than anyone can have access to check whether tagged white sharks are in the area.
Dr. Skomal said he has not tagged all of the white sharks in the area, so anyone using Sharktivity should be aware of that.
From their research, Dr. Skomal said, he has learned that the month of June is usually when sharks begin arriving off the Cape Cod coastline.
The peak months of shark activity are August, September and October.
Once the water temperatures start to drop in November, most sharks begin to scatter, and by mid-December, once the water temperature dips below 47 degrees Fahrenheit, the handful of individual sharks that remain will leave the area.
“There’s a very distinct seasonality that we can pull from our detection data,” Dr. Skomal said.
The shark activity coincides with some of the busiest summer months on Cape Cod.
Over the past eight years, Dr. Skomal has found the majority of white sharks to be spending their time on the Outer Cape; however, some sharks venture into Cape Cod Bay near the Upper Cape.