Despite thousands of whale watching trips each year to the renowned whale watching waters just north of Cape Cod, great white sharks are very rarely seen there.

While the apex predators’ primary habitat along the Atlantic-facing beaches of the Outer Cape is just 10 to 20 miles away, veteran whale watch naturalists with decades of experience have often never seen a great white in the open water.

This past weekend, a New England Aquarium Whale Watch vessel operated by Boston Harbor Cruises was beginning to return from a successful trip observing humpbacks east of Cape Ann when a sharp-eyed summer intern spotted a large dorsal (back) fin just below the water’s surface. Charlie Landa, a University of Arizona natural resources student, then notified head naturalist Heidi Hansen about the unidentified large shark. They pulled alongside the 10- to 12-foot shark and were able to take some good photos given the sunny day and the high cruising position of the shark. 

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Great white shark spotted during whale watch | Photo: Boston Harbor Cruises

Spotting an enormous shark on whale watches in this area is not unusual as the giant, harmless, plankton-feeding basking sharks are occasionally seen here throughout the summer. Although this great white shark was big, it was shorter than an adult basking shark and had a much pointier snout. Hansen suspected it might be a great white, but was unsure of the ID. She checked the images and quickly shared them with other naturalists via email. They also reached out to shark researchers at the Aquarium’s Anderson Cabot Center for Ocean Life, who confirmed the ID.

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Seals—a favorite meal of white sharks | Photo: Boston Harbor Cruises

What was the young adult white shark doing on northwest corner of the Stellwagen Bank National Marine Sanctuary? In addition to the humpback, minke, and finback whales commonly seen here this season, whale watch naturalists have also spotted grey seals swimming here dozens of miles from shore and their large colonies. Grey seals are the preferred prey of white sharks, and the increased visibility of white sharks along the Outer Cape appears to be closely tied with the increase in the grey seal population there.

After live large seals, white sharks will feed on floating whale carcasses. Last summer, several great whites fed on a dead minke whale near the tip of Cape Cod, but there were no reported whale carcasses in the Stellwagen area last weekend. As juveniles, when they are less than 8 feet long, white sharks feed exclusively on fish and have been incidentally caught and released at Stellwagen by charter fishermen. Maybe this shark was revisiting youthful haunts. More likely, white sharks, which migrate up the East Coast earlier in the summer, have been known to cruise throughout the Gulf of Maine and even into the waters of Maritime Canada.

The visitors on that New England Aquarium Whale Watch went looking for big whales, yet also got to see the most legendary big fish. For intern Charlie Landa, when he returns to school in the Arizona desert this autumn, he too has the ultimate fish tale to tell.

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