Can New England be home to a Great White shark?

The animal that was spotted eating a seal last weekend off North Beach in Chatham was probably a great white shark, state officials said yesterday. Lisa Capone, a spokeswoman for the Executive Office of Environmental Affairs, said that a shark specialist for the state had examined photos of the seal's carcass and interviewed witnesses and that the case "has the look of great white shark predation."

She said great whites are lone animals that travel 30 to 50 miles a day and have a slow metabolism, so that they can go several weeks or even up to a couple of months between feedings.

"It's likely far away, not going to eat again, and it was alone," she said.

A mammoth, bloodthirsty great white was featured in the movie "Jaws," which made many people think twice before going into the water. In 2004, a 1,700-pound great white made news in the state when it was trapped in a lagoon on Naushon Island off Falmouth for two weeks.

Tony LaCasse, a spokesman for the New England Aquarium, said great whites tend to stay offshore.

Large sharks are potential threats to people, he said, but "we're not part of their normal prey base. . . . We're not on their menu." The last shark-related death in New England was in 1936.

Still, he said, "if you see sharks in the water, you need to tear out of the water and listen to local officials."

John Mandelman, an associate research scientist at the aquarium, said sightings of great whites are "very, very rare."

He said the Chatham sighting didn't necessarily mean there were more sharks on the prowl. But, he said, people should always be cautious, always swimming with a partner and avoiding swimming at night or dusk or dawn, times when sharks are more active.

"It's sort of basic intuition," he said. "It behooves people to be aware of the fact that when they go swimming, they're entering a nonnative environment and there are wild animals."

Greg Skomal, a shark specialist for the Division of Marine Fisheries, said he determined that the animal was a great white based on photos of the seal carcass, interviews with two witnesses, and his 23 years of experience in the field.

Skomal said what witnesses described was a textbook attack, with a sudden violent "commotion in the water that resulted in a cloud of blood spray," followed by a period in which the shark circled before returning to eat its prey. Only the head and the fins of the seal washed ashore, which, Skomal said, was also indicative of an attack by a great white.