Seal attack prompts a shark warning

State and local officials urged Cape Cod beachgoers to be cautious and to avoid swimming near seals, after what appeared to be the second attack this month by a great white shark on a seal off a Chatham beach.

"The beach-going public should exercise common sense and be aware of their surroundings," Lisa Capone, a spokeswoman for the Executive Office of Energy and Environmental Affairs, said yesterday.

An unidentified sea creature was spotted eating a seal off South Beach in Chatham at midday Sunday, within sight of the shore, said Stuart Smith, the town's harbormaster. Smith's staff retrieved the carcass Monday morning.

Ann Hosmer, 62, of Chatham, said in a telephone interview last night that she did not see the shark attack the seal, "but I saw him lunching on it.

"There was a large, bloody pool. You couldn't see the shark, but twice during that time, its fin came out of the water."

Greg Skomal, a shark specialist for the state Division of Marine Fisheries who examined photos of the carcass Monday and yesterday, determined that the predator was probably a great white shark.

A great white was also pegged as the probable culprit in another attack on a seal Aug. 4 on Chatham's North Beach.

The town of Chatham issued a public notice yesterday, saying that "while it is rare for a shark to strike a human in the water, it can happen, and, given the recent local shark sightings, swimmers should exercise caution while swimming in Chatham's ocean waters.

"At this time, Chatham is not recommending that the beaches be closed, but simply that beachgoers and swimmers pay close attention to their surroundings while in the water and to not venture too far from shore," the notice said.

The notice also warned people not to swim near seals. Chatham is now the year-round home for a few thousand seals, the town estimates, and seals are one of the great white shark's favorite foods. Specialists believe some shark attacks on humans have happened because the sharks have mistaken people for seals.

Swimming with seals is "just not a wise thing to do," Smith said. "Don't swim with the seals, and you'll be fine."

Lisa Voutes, 40, of Barrington, R.I., who is vacationing in Chatham with her husband and two children, said she was concerned about the reports of a great white in the area.

"I think they came in closer because they were eating seals," she said. "You can see a lot of seals off South Beach. They beach themselves on the sandbars."

Selectman Ronald J. Bergstrom said he was not concerned about shark sightings scaring away tourists.

"All I can tell you is the town is packed, and I don't see anyone rushing back over the bridge," he said. "So far, I haven't heard any negative feedback of people not wanting to go in the water or hearing the 'Jaws' theme in their head.

"Something like this, it gets publicity, and there is some concern. But unless you wear a seal suit, I don't think you're going to have a problem."

While cautioning swimmers, officials emphasized that the sharks were behaving normally.

"A shark eating a seal, that's not an unusual thing," Capone said. "That's what sharks eat."

Skomal said there was no way to tell if the same shark had killed both seals or if a group of sharks was cruising along the coast.

Skomal said that great white sharks are usually elusive animals, so elusive it's hard to find them to do research on them, and that the probability of humans encountering them are "remarkably low."

He said he has been monitoring shark catching tournaments in the state for 20 years and while he has seen plenty of other types of sharks landed, he has never seen a fisherman land a great white.

A giant great white was featured in the 1975 hit movie "Jaws," exacerbating many people's fear of sharks. In 2004, a 1,700-pound great white made news when it was trapped in a lagoon on Naushon Island off Falmouth for two weeks. The last shark-related death in New England was in 1936.

Globe correspondent Marc Robins contributed to this report.