In the movie “Jaws,” a solitary great white prowls the coastal waters of a beach town, terrorizing locals.
For Chatham and Orleans beachgoers these past few weeks, it hasn’t been a lone shark doing a deadly flyby, but 10, possibly as many as 20, great whites cruising beaches, sometimes remarkably close to shore and people.
The sightings prompted beach managers to close beaches to swimming over Labor Day weekend in Orleans, and indefinitely in Chatham.
But what happens next year is anyone’s guess, scientists and town officials said.
Great whites primarily eat seals, not humans, and the growing seal colony on the beaches of Chatham’s Monomoy National Wildlife Refuge may be a draw that will keep them coming back — possibly in greater numbers — year after year.
The result could be more beach closures, on top of what tourists and townspeople already endure to protect endangered bird species such as plovers and least terns. The possibility, however remote, that someone could get bit, or killed, by a shark also casts a long, long shadow over Cape tourism.
“It’s something else extraneous to my business that I have to deal with,” said John Ohman, owner of Liam’s at Nauset Beach, a restaurant on the beach in Orleans. “Will people choose another town where they can go to rent, like Wellfleet or Eastham? Maybe go to the Bay side? It’s a great question that has no answer yet.”
Mary Corr, executive director of the Chatham Chamber of Commerce, noted that, right now, the town has seen something of an increase in tourism from curiosity seekers. But that interest only goes so far.
“Tourist-wise, people want to go to the beach,” she said. If they can’t, businesses suffer.
Protected by law
With both sharks and seals under federal protection, beachgoing may never be the same again.
“It’s entirely possible the area where they are sighted could see them coming back year after year, the seal colony being the key,” said George Burgess, director of the Florida Program for Shark Research in Gainesville. “White sharks love seals. If the seal colony is doing well, and their numbers are increasing, it’s probably a pretty good guess white shark (population numbers) will rise as well.”
That seals are thriving is obvious. Jim Gilbert, a professor of wildlife ecology at the University of Maine at Orono, specializes in seals and marine mammals. Seals rebounded from extremely low numbers after a bounty on seals was removed in 1964 in Massachusetts, and when the Marine Mammal Protection Act of 1972 made it a federal offense to hurt, harass, or kill one.
Harbor seal numbers increased fourfold between 1981 and 2001, to 99,000 individuals, mostly in Maine. Although gray seals are more prevalent in Massachusetts, population estimates are sketchy. Gray seals are mainly counted on Sable Island, a small remote island southeast of Nova Scotia. In 1962, just 120 pups were born there. Recently, 55,000 were born.
Gray seals migrate each spring from Sable Island to Monomoy and other places in the Gulf of Maine, and their numbers have skyrocketed on Monomoy and Muskeget Island off Nantucket with a combined population of as many as 10,000.
“Everything points to gray seals increasing throughout the Gulf of Maine,” Gilbert said. But there is no historic number, no upper limit yet known for seal populations. They are like deer of the sea, multiplying until either food becomes scarce, widespread disease wipes out large numbers, or predators thin their ranks.
While some cry out for culling, or driving away seals from Monomoy, the Marine Mammal Protection Act discourages those actions, allowing them in very limited circumstances, like protection of an endangered species of salmon, or to give indigenous tribes the opportunity to catch them as part of their treaty rights.
There is no provision in the marine mammal act, said Tom Eagle, a fishery biologist in NMFS Office of Protected Resources in Silver Springs, Md., for killing or harassing marine mammals because they attract a more dangerous predator. Also, protection under the act continues regardless of species abundance.
Shark sightings draw crowds in Chatham
The great white shark is also a protected species, covered under federal fisheries laws that prohibit anything but catch and release, and under an international treaty that restricts the trade of great white shark products and meat. Although some indicators show that these predators are both rare and in decline, scientists do not have any population estimates indicting their relative abundance or which way they are headed.
“Overall, they are rare compared with other species, maybe not in California and Australia,” said Nancy Kohler, chief of the Apex Predator Program for the National Marine Fisheries Service office in Narragansett, R.I. Great whites also travel long distances — one tagged shark went 12,000 miles in eight months — making study daunting.
Attacks here rare
Kohler said there are also a lot of unknowns about why they migrate and whether or not they return to an area.
Scientists long thought that areas of seal abundance like the Farallon Islands off San Francisco supported a resident population of great whites. But a recent tagging study involving a half-dozen sharks showed that many moved on, including one that ventured as far west as Hawaii.
Although they prefer warmer waters, great whites can maintain a body temperature five degrees warmer than the water temperature. That allows them to dive deep and to function in cold water. They’ve been seen as far north as Newfoundland. A 1985 study co-authored by NMFS scientist John Casey placed them in the Gulf of Maine from June through September. Kohler said they can tolerate surface waters with temperatures as low as 51 degrees.
“Once it gets that cold, they move off,” she said.
Lack of information means scientists can’t say whether this shark season was an anomaly or a harbinger of the future. Until last month, only one or two great whites have been spotted near the Cape. No one can yet say whether these were sharks returning to an area they were familiar with, or just happened by.
Like many who study great whites, Kohler was enthused that Massachusetts Division of Marine Fisheries shark scientist Greg Skomal tagged five of the great whites that gathered off Chatham. These satellite tags will record the water temperature, location, time and depth of these animals for the next five months, and that may give some clue as to why they were at Monomoy.
But the benefits of that research could be lost on swimmers, surfers and others who suddenly find themselves guessing if the dark shape that swam underneath them was a seal or a shark.
Shark attacks have been a virtual non-issue in Massachusetts, with just one, a fatality in 1936, compared to California with 73 attacks by great whites and eight fatalities since 1916.
Still, the likelihood of attack does increase with proximity to seals.
“Are our chances enhanced, the answer is pretty unequivocally, yes,” Burgess said. “Does that mean you will be bitten or attacked? Not necessarily.”
There are far more surfers in California waters using waters frequented by seals and sharks, Burgess said. While some are bitten, the incidents are extremely rare, less than one attack a year, and less than one fatality every 12 years.
But it’s that fear of the unknown that has led Chatham officials to keep their beaches closed as they try to plan for next year. Parks superintendent Daniel Tobin said his commission will be meeting in the off-season to see how best to protect beachgoers. He was especially concerned about the large numbers of swimmers who were ferried out to the barrier beaches where there are no lifeguards or routine patrols.
“We’ll talk to people who manage this in other parts of the country,” Tobin said. “It’s (foreign) to us here in New England.”
Burgess thinks the Cape needs a reality check.
“We’ve been pretty fat, dumb and happy when we go into the ocean. We think it’s like the backyard pool, but it’s not,” he said. Using common sense when sharks are in the water, along with lifeguards watching the ocean, could go a long way to averting tragedy.
“Having sharks in an area is not the kiss of death,” he said. “I don’t think this signals the end of recreational swimming in these waters for the rest of the year or in summers to come.”