ANDY KELLY, an experienced striper and tuna fisherman who lives on Plum Island, shared the following story with me:
It was a warm, windless evening in August. A perfect night for striper fishing. Moonlight danced on the water as our boat rocked gently just off the southern end of Plum Island. It was one of those magical nights when bioluminescence—a light-producing chemical reaction emanating from plankton—sparkled in the water from the slightest turbulence. As we cast our lures and retrieved them, they looked like small comets racing toward the boat. And when a striper hit, the bioluminescence seemed to explode like fireworks. Little did we know the fireworks were just beginning.
I hooked a large striper, probably over 20 pounds, and pulled it up near the side of the boat. As we got ready to net the fish, we saw what looked like a large ball of fire moving swiftly under the water headed straight for the boat. The shark swooped in and ate the striper whole, and then disappeared in an instant.
Andy estimates the white shark was 10 to 12 feet long. If you think this is just one of those tall tales fishermen tell, you’d be wrong. Experiences like Andy’s have occurred many times in recent years in the waters from Marblehead to the mouth of the Merrimack River.
Dave Rimmer, a charter captain in North Shore waters for over 20 years, also had an encounter near the southern end of Plum Island. “A white shark swam between my boat and shore in six to eight feet of water. It was a foggy morning, so the whole scene was a bit surreal.” He estimates the shark was 15 to 17 feet long.
The increasing frequency of encounters like these is not surprising. Unless you’ve been living under a rock, you’re probably aware of what’s been going on at Cape Cod. Over the last 20 years, Cape Cod has become one of the largest, if not the largest, white shark gathering places in the world. According to a population study reported last summer in Scientific American, “researchers estimate that about 800 individual white sharks visited the sampling area from 2015 to 2018.” That sampling area was a 43-mile stretch of coastline from Monomoy in the south to Race Point in the north.” Race Point is approximately 85 miles from Gloucester as the crow flies.
So, why are these sharks becoming such regular visitors? You can draw a straight line from the Marine Mammal Protection Act of 1972, which made it illegal to harass, capture, or kill any marine mammals, from polar bears to manatees to whales. Gray seals, a favorite prey of white sharks, had been native to New England waters for thousands of years before they were systematically exterminated through “nuisance killings,” bounty hunting, and as the by-catch of commercial fishing enterprises. By 1960, there were virtually no gray seals in Massachusetts waters. Fast forward to now, and there are an estimated 30 to 50,000 gray seals on the Cape, with four pupping colonies on the Cape and Islands.
Renowned shark expert Greg Skomal, who has studied sharks in New England waters since the early 80s, says, “As these sharks migrate north up the Eastern Seaboard, they generally stick to the continental shelf. They don’t come close to shore until they reach Cape Cod. They’re hardwired to prey on seals.” Skomal believes they detect scent trails leading them to the shallow waters off the Outer Cape. Some summer at the Cape while the majority move “further north and spread out over a much larger geographic area to the Gulf of Maine and all the way to the Gulf of Saint Lawrence.” Skomal refers to the North Shore as a “transient area.”
The DMF, in partnership with the Atlantic White Shark Conservancy (AWSC), has been studying white shark population dynamics and behavior for over 10 years. As part of their research, they’ve affixed acoustic tags to over 300 individual sharks at Cape Cod. Those tags are detected by different arrays of receivers up and down the East Coast and well into Canada. A receiver at the mouth of Marblehead Harbor detected four individuals in the summer of 2022, with a total of 20 detections. Those four sharks ranged between 8 and 12 feet long. Over 80 sharks tagged at Cape Cod showed up on Canadian receivers that same summer.
“The vast majority of sharks are untagged,” says John Chisholm of the New England Aquarium, who monitors and confirms all white shark sightings for AWSC’s “Sharktivity” app. So, the number of tagged sharks is just a small percentage of the overall population in our coastal waters.
Sharktivity is a “citizen science” initiative. All shark sightings are reported by ordinary folks and then confirmed before posting by John Chisholm. The app also reports dead or injured seals with bite wounds showing the unique dentition of white sharks. Two such seals washed up on North Shore beaches last summer, one at West Beach and the other at Long Beach in Gloucester. The dead humpback whale that washed up at Swampscott recently also had shark bites. (You can download the Sharktivity app at Apple or Google app stores.)
Although there are public safety issues and other concerns, the comeback of gray seals and white sharks to New England waters is a conservation success story. We are seeing in real time the re-establishment of the trophic food web with once-abundant apex predators (the sharks) and meso-predators (the seals) returning to change the balance of the near coastal ecosystem, much as the reintroduction of wolves has changed the Yellowstone ecosystem, in many ways for the better. After all, it’s their natural habitat, not ours.
Jim Behnke is a Manchester-based nature writer whose stories have appeared in On the Water, Outside, and Scientific American. He has been a contributor to The Cricket since 2019.
