Sharks Are Spotted Off Long Island. Scientists Say Don’t Panic.

Police helicopters scanning the waves for dorsal fins. Bathers pacing on beaches, waiting for the all-clear to go back in the water. A mysterious bite on a lifeguard’s leg.

Along New York’s Long Island beaches, a handful of shark sightings over the past week has prompted local officials to briefly close several beaches, hold oceanside news conferences and send police officers out on “shark patrol” on boats and jet-skis.

But while the atmosphere of anxiety carries a whiff of the 1970s blockbuster “Jaws” — in which a fictional Long Island mayor covers up a threat from a giant shark with a scientifically improbable grudge against humans, to disastrous effect — scientists emphasize that there is not an increased danger to swimmers.

In fact, they say, more sharks have been seen mainly because more people are looking for them — including municipal shark patrols that expanded after a possible rare case of a shark bite on Fire Island in 2018 — and they are more easily recording and sharing images.

“We have a mantra: There are more people seeing sharks because there are more people, with more smartphones and drones and social media,” said Hans Walters, a field scientist with the Wildlife Conservation Society who has studied sharks in the area for a decade.

The jitters began on Monday, when a lifeguard at Jones Beach on Long Island felt something bump against him while he swam and emerged from the water with a gash on his calf. The next day, a shark sighting was reported there, prompting officials to suspend swimming for a few hours. Sightings were reported at Long Beach and Lido Beach on Wednesday, and on Thursday more shark reports led to shutdowns.

The Nassau County executive, Laura Curran, announced that she was increasing shark patrols “out of an abundance of caution,” urging residents to “stay calm, use common sense and follow lifeguard instructions.”

Some experts find themselves in a tricky position: They do not want to belittle anxious swimmers or local politicians, but they also doubt that shark patrols are effective or necessary and worry that the hoopla will fuel unwarranted terror of sharks.

“The shark does not want to eat you,” said Christopher Paparo, a naturalist who manages a marine lab at Stony Brook University. “We’re not on that menu. But it’s tough — you don’t want to be the town council person who says ‘Ah, don’t worry,’ and then God forbid a very rare event happens. You don’t want to be the mayor in ‘Jaws.’”

More than 20 species of sharks have always been in the waters off New York and New Jersey, Mr. Walters said, adding, “The risk of one biting a human is infinitesimal.”

People are more likely to be killed in a car crash on the way to the beach — or even while making toast — than by a shark, Mr. Paparo noted.

If shark numbers are increasing lately in the waters off New York and New Jersey — a matter of dispute among experts, who say some species are rebounding and others newly threatened — Mr. Paparo said that would be a good thing. It would show that the animals are recovering from pollution and overfishing that has reduced the global shark population by 70 percent since 1970.

Sharks, whales and other species are benefiting from the return of schooling fish known as menhaden, which are a key prey for larger animals, Mr. Paparo said.

“We need sharks,” he added. “It shows a healthy ecosystem. We need the top predators as much as we need the menhaden. But that’s not a story that sells. People want the shark attack story.”

Another factor, he said, is that with climate change warming the waters, some species once rarely seen north of southern New Jersey are now spotted more often around Long Island.

Experts offered one safety tip: Avoid swimming near large schools of bait fish, birds that are feeding or choppy waters.

It hasn’t helped, scientists said, that the recent spate of sightings came right after Shark Week, a blitz of gaudy programming that annoys scientists so much that the Wildlife Conservation Society issued a list of dos and don’ts for the news media to reduce sensationalism in shark coverage.

“Sharks are not mindless eating machines,” it points out. Another piece of wisdom: “The most dangerous animal in the ocean: People.”

“By the way, I’m a big ‘Jaws’ apologist,” Mr. Walters said. “It’s a great movie. But it’s not a scientific treatise on sharks, and wasn’t meant to be.”