July 11 (Bloomberg) -- A shark, possibly a great white, was seen cruising the same waters where the movie ``Jaws'' was filmed, prompting the town of Edgartown, Massachusetts, to let residents know they're now swimming ``at your own risk.''

A warning was posted on Edgartown's Web site saying sharks had been sighted at South Beach on Thursday.

``We had a sighting yesterday, a confirmed sighting,'' said Marilyn Wortman, spokesman for the Parks Department in the Martha's Vineyard town. ``We have had nothing today and the beaches are open.''

Great white visits to Massachusetts waters are rare; however, the sharks have turned up at least twice in the last four years.

Last August, one or more great white sharks made meals of seals off Cape Cod beaches near Chatham. In 2004, a 1,750-pound (794 kilogram) great white swam into an inlet off Naushon Island, near Martha's Vineyard, and stayed there for more than two weeks, resisting biologists' efforts to evict it.

The great white is the largest predatory fish in the world, according to the Web site of the Monterey Bay Aquarium in California. The sharks can reach a length of about 22 feet (6.7 meters) and weigh more than two tons.

The island of Martha's Vineyard, about 70 miles (113 kilometers) south of Boston, is where Steven Spielberg turned author Peter Benchley's novel ``Jaws'' into a 1975 motion picture. Long Island was the fictional setting of the book.

Shark Spotter

The Massachusetts Fisheries and Wildlife Division and the U.S. Coast Guard received several reports of a shark in the area yesterday, said Lisa Capone, spokeswoman for the state's Executive Office of Environmental Affairs.

The state then dispatched a pilot to search the area by air. After several hours the pilot, a fish spotter, failed to find any sharks, Capone said.

She said there aren't any plans to continue the search today.

``The beaches are safe and secure,'' Wortman said. ``People didn't want to get out of the water yesterday.''

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net.

Last Updated: July 11, 2008 11:45 EDT