Seals to blame for shark attacks, experts say

(CBS News) CHATHAM, Mass. - August arrives Wednesday and with it comes the real dog days of summer. But on some beaches, it's more like shark days.

A swimmer was attacked off Cape Cod, Mass., Tuesday. It turns out, the best of intentions many have lured sharks closer to shore.

The sandy beaches of Cape Cod lure tourists, but on Monday there was another visitor that was not so welcome.

"A shark attack," said a witness on a 911 call. "He is bleeding and he is bounded -- both ankles been bit --we need 911."

Great white sharks coming closer to shore, people
Mass. beach remains open after swimmer was bitten
Expert: Great white likely attacked Mass. swimmer

A man was hauled-off the shore in Truro, Mass. on a stretcher after being bitten on the legs while swimming. Eyewitness told tales of a shark attack.

One witness described seeing the fin: "It was torqueing and then it was like, 'What did we just see?' Because it was like out of a movie -- but you know that was a shark."

Today, scientists confirmed the man was likely bitten by a great white shark. It would the first known attack in these waters since 1936.

Capt. David Murdoch, who operates boat tours on the Cape Cod shore, said thousands of seals could be attracting sharks to the area.
Capt. David Murdoch, who operates Chatham Boat Tours on the Cape Cod shore, said thousands of seals could be attracting sharks to the area. CBS News

The man was able to swim to shore and was brought to a local hospital in stable condition.

While shark sightings are rare along Cape Cod beaches, officials have tagged nine great white sharks this year. And that's what tourists want to see.

Asked how many people come wanting to see sharks, Capt. David Murdoch replied, "all of them."

Murdoch has operated his Chatham Water Tours for 15 years. He says one thing that is bringing sharks to the coast is food, in the form of a booming seal population.

Walter Szulc Jr., in kayak at left, looks back at the dorsal fin of an approaching shark at Nauset Beach in Orleans, Cape Cod, Mass., July 7, 2012. An unidentified man in the foreground looks toward them. AP/Shelly Negrotti

Murdoch takes tourists to see seals, which he says are common in the waters. While rain kept the tourists away when CBS News visited, Murdoch showed us how seals line the shore. Scientists say it may be food -- in the form of a booming seal population -- that's attracting sharks closer to the shore. There are now roughly 350,000 living on the North Atlantic coast.

Thousands and thousands of more seals are coming to the coast, Murdoch said. They're protected because of the 1972 federal Marine Mammal Protection Act, which makes it illegal to harm these animals.

With a life-span of 30-40 years, the seals will continue to be a tempting target for sharks along these waters.