Today, a great white shark sighting is more likely to elicit curiosity than fear. Cape Cod sharks even have their own advocacy group. Photo by Steven Benjamin/iStockphoto/Thinkstock

When a tourist from Colorado was bitten by a great white shark last summer while swimming off Cape Cod, an excited media made predictable comparisons to the 1975 blockbuster Jaws. The 50-year-old man, who was fortunate to survive with bites to his legs but with all his limbs still attached, was the first human to be attacked by a shark in Massachusetts waters since 1936. As more sighting reports poured in, 2012 became Cape Cod’s “Summer of the Shark.”

We all love a good shark scare, but in this case the coverage wasn’t completely exaggerated. In 1974, when Jaws was filmed just off the cape on Martha’s Vineyard, great white sharks—known to marine biologists simply as white sharks—were rare, with one or two spotted in New England waters each year. In 2012, there were more than 20 confirmed sightings at Cape Cod beaches, and so far this summer two beaches have been closed temporarily after the sharks’ telltale dorsal fins were seen just offshore. Scientists have now tagged 34 great whites off of Cape Cod, and the data show the minivan-size fish sticking to a clear migration pattern—down south or out to sea in the winter and, like the Kennedys, back to the cape every summer.

Jaws aside, these sharks are not hunting unsuspecting vacationers. They’re after seals, which have soared in population in recent years thanks to a national conservation effort that has proven enormously successful—some might say too successful. The shark resurgence comes down to simple food chain economics, but it also shows how wildlife conservation can sometimes have weird and unpredictable consequences.

Seals have a tendency to hang around boats and snatch fish from nets, and for centuries people fishing off New England would kill any seal they saw. Between the late 19thcentury and the early 1960s, the state of Massachusetts offered a bounty of up to $5 for every pinniped slaughtered. By 1972, harbor seals, once common on Cape Cod, were becoming rarer, and gray seals were all but wiped out. But that year Congress passed the Marine Mammal Protection Act, a law that forbids the killing, capture, or harassment of whales, dolphins, polar bears, manatees, seals, and similar animals—creatures that commercial hunting and other human activity had taken, in some cases, to the brink of extinction.

The act has been a tremendous success. In March 2011, a one-day count of gray seals in Massachusetts waters found 15,756 of them, compared to 5,611 in 1999. The National Oceanic and Atmospheric Administration estimates that the gray seal population in the Western Atlantic grew annually between 6 and 9 percent during the past three decades. Today, seals haul out and lounge on some beaches in enormous numbers, and it’s common to see them swimming alone or in pairs up and down the Atlantic side of Cape Cod. That’s a lot of shark bait. One recent afternoon at Nauset Light Beach, part of the Cape Cod National Seashore, I stood on the sand with a group of beachgoers watching a sleek brown head bobbing just past the breakers. Having been warned by prominent signs not to swim near seals, none of us were going near the water. “Does this mean there are sharks out there?” one woman asked, in a tone that revealed both anxiety and fascination.

Seals are taking the blame for luring sharks, and at the same time the old resentment is flaring up among some fishermen, who say seals are harming the cape’s struggling fishing industry. Gordon Waring, a seal specialist at the NOAA, cautions that marine biologists don’t actually know how seals interact with fisheries, and so far there is no sign that they are eating more than their habitat can support. But it is clear that seals are attracted to fishing boats and piers, and fishermen who watch seals stealing fish from their nets justifiably resent the greedy creatures, which the Marine Mammal Protection Act says can’t even be shooed away (that would be “harassment”). Fish stocks, particularly of cod, are down, and while that’s mostly due to other factors such as decades of overfishing, seals are a visible target for blame. There has even been talk of a seal cull, and a Nantucket-based group calling itself the Seal Abatement Coalition is lobbying Congress to remove gray seals from the list of species covered by the Marine Mammal Protection Act. Seal culls are already a regular occurrence in Canada, which has historically had much larger seal populations.

That might all sound like we’re headed for a return to the era when seals were shot on sight and sharks stalked and killed to protect swimmers, but in truth there are heartening signs that humans’ relationship with ocean life off Cape Cod will be better this time around. While a horror movie starring an animatronic shark could once keep people out of the water all summer, today, a great white sighting is more likely to elicit curiosity than fear. Cape Cod sharks even have their own advocacy group.

“As tragic as a shark attack is, it would be more tragic not to have sharks in our oceans,” says Cynthia Wigren, who last summer helped found the Atlantic White Shark Conservancy, a Cape Cod group (with an adorable smiling shark logo) that raises money for education and research. Greg Skomal, a shark biologist with the Massachusetts Division of Marine Fisheries, has been leading an effort to tag great whites and study their migration patterns. He sees the sharks’ return as an indication that the marine ecosystem off New England is returning to normal, with sharks playing a crucial role as apex predators. That’s great news, ecologically speaking. But as he points out, “That does not take into consideration the negative impacts that can occur with the restoration of a natural ecosystem.”

Sharks are not the brightest animals in the sea. Humans are not a preferred prey animal, but sharks looking for seals sometimes get confused. Given that their primary way of interacting with the world is to use their mouths (in a way, maybe they are the “mindless eating machines” of the Jaws trailer), a shark may give a human swimmer a good “gumming,” Skomal says, before realizing it hasn’t found a seal. “If sharks wanted to eat humans, we’d have a hell of a lot more shark attacks,” Skomal says. “These are instinctive wild animals, and they make mistakes every now and then. It’s extremely rare, but nonetheless they make mistakes.”

While a great white shark’s honest mistake can still be terrifying—just ask that tourist who got bitten last summer—sharks’ public image seems to be evolving as conservationists educate people about the need to protect vulnerable species and as our understanding of nature becomes more sophisticated. We may be learning to adapt to nature, rather than forcing it to adapt to us.

Nowhere is that more apparent than in Chatham, a 300-year-old fishing village on the elbow of Cape Cod that has found itself at the epicenter of the wildlife resurgence. InJaws, small town leaders tried to cover up shark attacks, fearing they would be bad for business. But Lisa Franz, director of Chatham’s Chamber of Commerce, says the opposite has been true—at least so long as no one has been seriously hurt. While the local fishing industry is struggling, other businesses are capitalizing on people’s curiosity about sharks and the seals they feast on. Shark T-shirts and stuffed toys are flying off gift shop shelves, and there’s talk of making Chatham an ecotourism destination.

“When the first shark hits the newspapers, we get busier earlier,” says Keith Lincoln, who runs a Chatham cruise business that specializes in seal tours. His “office,” parked recently in a lot at the Monomoy National Wildlife Refuge, is a Honda Odyssey with an inflatable shark strapped to the roof—“a hit with the tourists,” he says. But while passengers might say they want to see sharks, Lincoln is not sure they know what they’re getting into. He has seen great whites swimming near the beach, their huge forms casting dark shadows on the sand below. “We usually don’t tell people,” he says. “They leave here all brave, but when they see a fish that’s as big as the boat, they’re not so brave.”

Then again, he might just need a bigger boat.

Watch Discovery Channel’s joking take on the shark frenzy for seals here.