Great white sharks take center stage off Chatham, Mass.

The Fourth of July weekend marks the unofficial start to summer for people across the U.S., but in  Chatham, Mass., it also means the beginning of the great white shark watch.

The Cape Cod town has become perhaps the top location to view the notorious predators, which arrive seasonally to prey upon gray seals. 

This is not to imply that an increasingly large influx of white sharks in recent years has transformed Chatham into anything resembling the fictional New England town of Amity in the 1975 horror-thriller, "Jaws." The last unprovoked shark attack in Massachusetts waters, after all, occurred in 1936.

But Chatham is becoming famous for its great whites, which teem ominously in the imaginations of beach-goers, and lure thousands of tourists hoping to spot one.

"The seal population has reached some critical level that the likelihood of seeing a white shark now has increased," Greg Skomal, a shark expert at the Massachusetts Division of Marine Fisheries, told Bloomberg News.

The Bloomberg story is about how Chatham, located about 75 miles south of Boston, has become a tourist trap because of its white sharks, and how some wish it could be known for its other qualities.

"We wanted to be known as a nice, quiet, laid-back community," said Mike Ambriscoe, the Chatham fire chief. "We've been having this problem where sharks have been visiting us. It certainly does put us in the limelight."

Chatham does not have a monopoly on the white shark/beachgoer phenomenon. The Fourth of July holiday weekend in Southern California, thanks to a flood of people to beaches and into the ocean, typically produces a white shark sighting or two, followed, when warranted, by lifeguard warnings. (At least one expert believes white shark numbers are increasing off California.)

That's because juvenile white sharks -- those to about 10 feet long -- utilize coastal waters as a nursery, feeding on fishes, rays and smaller sharks. These sightings invariably appear on the Shark Research Committee website.

But the phenomenon off Chatham is more centralized and predictable, so much so that scientists were able to tag more than a dozen specimens there during the past two summers. (There has been at least one sighting in cape waters already this season.)

Chatham, a town of about 6,500, will not forget the shark warning issued to swimmers by the U.S. Coast Guard last summer, just as the July 4 holiday weekend got underway, or the flood of tourism that ensued.

Business boomed in many stores and restaurants, and snarling traffic jams were attributed to shark-seeking visitors.

Nobody complains about more business, but it would seem unsettling for town leaders for that to be credited to predators that can measure 20 feet and weigh 4,000 pounds. "The first year this all happened, I was really nervous about it and would say to others, don't talk about it, we don't want shark merchandise," said Lisa Franz, executive director of the Chatham Chamber of Commerce. "The second year, I embraced it. The third year, come on down, we'll have a shark statue for you."

Fortunately, unlike the sensational situation depicted in "Jaws," the white sharks off Chatham do not pose a threat to swimmers, experts say, as long as they utilize beaches a safe distance from the seal gathering. The pinnipeds, with their high fat content, are the chief reason for the presence of the sharks.

The slow but steady growth of the seal population, experts say, is attributed to the passage of the Marine Mammal Protection Act in 1972. That helps to explain an increase in white shark sightings.

That, and perhaps the fact that a lot more people are on the lookout these days.

-- Images are courtesy of the Massachusetts Division of Marine Fisheries