Great white sharks, which can be up to 20 feet long, do not hunt humans but may mistake them for prey because they are about the same size as seals and other marine mammals, experts said.

“Pretty much every shark bite is an accident,” said Gavin Naylor, director of the Florida Program for Shark Research at the Florida Museum of Natural History. “It’s mistaken identity.”

The chance of being bitten by a shark is statistically low. Last year, there were 88 unprovoked shark attacks worldwide, including five fatalities, according to the program’s International Shark Attack File. The United States, with its long coastlines and busy beaches, has historically had the most attacks — overwhelmingly in Florida — followed by Australia, South Africa and Brazil.

Experts say a new risk area is emerging in Massachusetts, where a thriving marine life population is colliding with tourists in ways not seen in almost a century, since a teenage boy was fatally bitten while swimming in 1936.

The state, which has had just a handful of attacks since the 1800s, has now had at least two in a matter of weeks. Another man was bitten off Cape Cod last month near Longnook Beach in Truro, but he fought off the shark and survived.