By Lawrence Crook and Bob Crowley, CNN
Chatham, Massachusetts (CNN)The Cape Cod National Seashore is home to some of the most beautiful beaches in the United States, but it's also known for its abundance of great white sharks.
"Jaws" was filmed on nearby Martha's Vineyard, adding to the local shark lore.
Thousands of seals call the shoreline their home. And where seals go, sharks go.
"I wouldn't go swimming out there," a Cape Cod resident told CNN while watching the seals with his elderly father in Chatham Harbor recently. "Couldn't pay me to do it!"
When the kids are back in school and family vacations have come and gone, local beaches are largely empty.
On a recent fall day, a young man on his surfboard was the only person around. He sat about 50 yards offshore waiting for the next big wave -- completely unaware two adult great white sharks were swimming just 25 yards away.
Biologists from the Atlantic White Shark Conservancy are helping spot sharks to study the species and protect the public.
But someone was watching out for the man above.
"We've got two sharks swimming about 25 yards away from a surfer," Wayne Davis called over the radio from his airplane a few hundred feet above the young man.
Davis is a fishing spotter pilot, who is contracted by the Atlantic White Shark Conservancy to patrol the shoreline for sharks and radio back confirmed sightings to a boat of eager scientists below.
While the sharks might keep some people from wading far from shore, this group of biologists does the opposite -- spending a majority of their time patrolling the shoreline studying the kings, and queens, of the ocean.
The AWSC funds great white shark studies to increase knowledge of the Atlantic white shark and keep the public safe.
From sighting to app alert
"I'm calling it in," Cynthia Wigren, the founder of the Atlantic White Shark Conservancy, announced as she grabbed her iPad.
Wigren quickly added the confirmed sighting to the group's Sharktivity mobile app. The app was developed by the AWSC in collaboration with the Cape Cod National Seashore, the Massachusetts Division of Marine Fisheries, and officials from Cape Cod and other shore towns.
Wigren also alerted the Regional Shark Working Group. Established in 2012, the group consists of local public safety officials from several shoreline communities. When the group is alerted of a shark sighting, they assess the credibility.
"If they determine the sighting is credible, the lifeguards will pull all of the swimmers out of the water for an hour. If no further evidence of the shark presents itself within that hour, the lifeguards will let the swimmers back into the water," said Leslie Reynolds, chief ranger at the Cape Cod National Seashore.
"Every day, our lifeguards work on their shark sighting drills ... which focuses on identification, communication and notification," Reynolds said.
So far this year, the Cape Cod National Seashore beaches have pulled swimmers out of the water nine times due to confirmed shark sightings close to shore, according to Reynolds.
"We've discovered that the white shark numbers are increasing here off of Cape Cod, and have been for roughly the last decade, and we firmly believe that that's driven by the growing seal population," said Dr. Greg Skomal, program manager and senior marine fisheries biologist for Massachusetts.
Skomal, a regular on Discovery Channel's "Shark Week," has been studying marine life for more than 30 years. He and fellow biologist, John Chisholm, were the first to successfully tag and track great whites in the northwest Atlantic Ocean.
Since 2009, 100 great white sharks have been tagged off the coast of Cape Cod, according to the AWSC.
"Having seen and grown up during the era of 'Jaws,' one would expect that a touristy area like Cape Cod, which is a massive tourist resort destination, would be concerned about the presence of these animals. What's really quite refreshing, and surprising to me, is the fact that we're not seeing that. We're seeing folks that are almost embracing them, fascinated by them, are interested in them. They're drawn to what we're doing and they're drawn to these sharks, so that's refreshing," Skomal said.
30 sharks spotted in single day
As the boat pulled up to the surfer, Wigren yelled, "Get out of the water!"
The surfer, recognizing the danger, quickly got out and waved a thank you. As the boat continued to patrol the shoreline, people on the beach clearly recognized them and waved as they passed by.
Up above, Davis continued to call in sightings over and over again. Roughly 30 sharks were spotted that day.
One of the sharks investigated by the team had been previously tagged by the AWSC. The shark's name is Specialist Brian Arsenault. The 12-foot shark was named after a 28-year-old soldier from Northboro, Massachusetts, who was killed in Afghanistan in 2014.
"Brian's cousin, Elliot, reached out to us saying that Brian loved white sharks and that the two of them often talked about planning a cage diving trip in Mexico. We happened to tag a 12-foot male white shark the day Spc. Arsenault passed away. I've stayed in touch with his family, and we absolutely love that his family is following our operation," Wigren said.
Wigren took a photo of the shark and sent it to Brian's mother, who follows the AWSC's operation closely.
"Half of the ones, on average, that we see, we've seen before. The other half are brand new to us," Skomal said.
Attacks on humans are rare
Despite years of research, Skomal said scientists still "know virtually nothing about white shark migratory habits and behavior in this part of the world."
And even though the Cape Cod shoreline boasts an abundance of great white sharks, attacks on humans are rare.
In 2012, Chris Myers and his 16-year-old son ignored the warnings and decided to swim to a sandbar that was roughly 500 yards off the coast of Cape Cod's Ballston Beach. Before the two could get to the bar, they realized how far they were from shore and decided to turn around. It was at that moment the shark attacked.
"I felt like I was caught in a vise," Myers said in an interview he gave to CNN. Myers was bit in the leg by an adult great white shark and several of his tendons were severed. He received 47 stitches to his right leg. His son was uninjured.
Another incident occurred in 2014 when two women kayaking in nearby Plymouth were attacked by a great white. Their boats were ruined but they were not injured
According to the Global Shark Attack File, there were 59 shark attacks in the United States in 2015, with one fatality in Hawaii.
"Our mission is to learn as much as we can about the great white sharks to help sustain the population, while simultaneously learning as much as we can about them to help people make informed choices when they decide to venture into the water," Wigren said.