VINEYARD HAVEN, Mass. – Lewis Pugh has followed an unspoken rule during his career as one of the world’s most daring endurance swimmers: Don’t talk about sharks. But he plans to break that this week on a swim around Martha’s Vineyard, where “ Jaws” was filmed 50 years ago.

The British-South African was the first person to complete a long-distance swim in every ocean of the world — and has taken on extreme conditions everywhere from Mount Everest to the Arctic.

“On this swim, it’s very different: We’re just talking about sharks all the time,” joked Pugh, who will, as usual, wear no wetsuit.

For his swim around Martha’s Vineyard in 47-degree (8-degree Celsius) water he will wear just trunks, a cap and goggles.

Pugh, 55, is undertaking the challenge because he wants to change public perception around the now at-risk animals — which he said were maligned by the blockbuster film as “villains, as cold-blooded killers.” He will urge for more protection for sharks.

On Thursday, beginning at the Edgartown Harbor Lighthouse, he will swim for three or four hours in the brutally cold surf, mark his progress and spend the rest of his waking hours on the Vineyard educating the public about sharks. Then, he’ll get in the water and do it again — and again, for an estimated 12 days, or however long it takes him to complete the 62-mile (100-kilometer) swim.

He begins the journey just after the New England Aquarium confirmed the first white shark sighting of the season, earlier this week off the coast of Nantucket.

“It’s going to test me not only physically, but also mentally,” he said, while scoping out wind conditions by the starting line. “I mean every single day I’m going to be speaking about sharks, sharks, sharks, sharks. Then, ultimately, I’ve got to get in the water afterwards and do the swim. I suppose you can imagine what I’ll be thinking about.”

A world without predators

Pugh said the swim will be among the most difficult he’s undertaken, which says a lot for someone who has swum near glaciers and volcanoes, and among hippos, crocodiles and polar bears. No one has ever swum around the island of Martha’s Vineyard before.

But Pugh, who often swims to raise awareness for environmental causes — and was this year named the United Nations Patron of the Oceans — said no swim is without risk and that drastic measures are needed to get his message across: Around 274,000 sharks are killed globally each day — a rate of 100 million every year, according to the American Association for the Advancement of Science.

“It was a film about sharks attacking humans and for 50 years, we have been attacking sharks,” he said of “Jaws.” “It’s completely unsustainable. It’s madness. We need to respect them.”

He emphasizes that the swim is not something nonprofessionals should attempt. He’s accompanied by safety personnel in a boat and kayak and uses a “Shark Shield” device that deters sharks using an electric field without harming them.

Pugh remembers feeling fear as a 16-year-old watching “Jaws” for the first time. Over decades of study and research, awe and respect have replaced his fear, as he realized the role they play in maintaining Earth’s increasingly fragile ecosystems.

“I’m more terrified of a world without sharks, or without predators,” he said.

The ‘Jaws’ effect on sharks

“Jaws” is credited for creating Hollywood’s blockbuster culture when it was released in summer 1975, becoming the highest grossing film up until that time and earning three Academy Awards. It would impact how many viewed the ocean for decades to come.

Both director Steven Spielberg and author Peter Benchley have expressed regret over the impact of the film on viewers’ perception of sharks. Both have since contributed to conservation efforts for animals, which have seen populations depleted due to factors like overfishing and climate change.

Discovery Channel and the National Geographic Channel each year release programming about sharks to educate the public about the predator.

Greg Skomal, marine fisheries biologist at Martha’s Vineyard Fisheries within the Massachusetts Division of Marine Fisheries, said many people tell him they still won’t swim in the ocean because of the sheer terror caused by the film.

“I tend to hear the expression that, ‘I haven’t gone in the water since ‘Jaws’ came out,’” he said.

But Skomal, who published a book challenging the film’s inaccuracies, said “Jaws” also inspired many people — including him — to study marine biology, leading to increased research, acceptance and respect for the creatures.

If “Jaws” were made today, he doesn’t think it’d have the same effect. But in the 1970s, “it was just perfect in terms of generating this level of fear to a public that was largely uneducated about sharks, because we were uneducated. Scientists didn’t know a lot about sharks.”

Skomal said the biggest threat contributing to the decline of the shark population now is commercial fishing, which exploded in the late 1970s and is today driven by high demand for fins and meat used in food dishes, as well as the use of skin to make leather and oil and cartilage for cosmetics.

“I think we’ve really moved away from this feeling, or the old adage that, ‘The only good shark is a dead shark,’” he said. “We’re definitely morphing from fear to fascination, or perhaps a combination of both.”