Is there such a thing as a ‘problem shark’? Plan to catch repeat biters divides scientists | Sharks

FThe first was the French tourist, killed by swimming Saint-Martin in December 2020. The director of a nearby water sports club took place in a canoe to help, only to find his lifeless body on the ground, a gaping injury where part of his right thigh should have been. Then, a month later, another victim. Several Caribbean islands, a woman diving with Tuba off St Kitts and Nevis was seriously bitten on her left leg by a shark. Fortunately, she survived.

Shortly after the fatal incident in December, Eric Clua, a marine biologist at the Practical School of High Studies in Paris, received a telephone call. The island nations often ask for his help after a shark bite, he says: “Because I present a new vision … I say:” You have no problem with the sharks, you have a problem with a shark. »»

Conflicts of Humanity-Shark are not only the result of accidents or chance, says Clua. Instead, he says there are things such as problems: daring individuals who may have learned, perhaps still young, that humans are prey. It is a controversial position, but Clua thinks that if it is true – and if it can identify and remove these Sharks of problems – it could dissuade the authorities from taking forms of even more extreme remuneration, including networks.

Although the slaughter of sharks after the conflicts of human benches become less common and are generally considered by scientists as ineffective, they always occur. One of the last big successors took place near Reunion, a French island in the Indian Ocean, between 2011 and 2013, leading to the death of more than 500 sharks. Even that was not enough for some – four years later, a professional surfer called for daily shark warming up near the island.

And so, in the aftermath of the French tourist’s death in Saint-Martin, when one of Clua’s contacts called to explain what had happened, he remembers having said to them: “Go ahead on the beach … I want to flood injuries.”

After this bite and that which occurred a month later, the health professionals collected mucus samples that the shark had left to send to analyze, although it took weeks for the results to return. But as Clua and his colleagues describe it in a study published last year, DNA analysis confirmed that the same tiger shark was responsible for the two incidents.

Even before the DNA test was completed, however, the analysis of the teeth marks left on the victim of Saint-Martin and the dental fragment collected on his leg, suggested that the aggressor was a tiger shark (GALEOCERDO CUVIER)) about 3 meters (10 feet) long. Armed with this knowledge, Clua and his colleagues decided to catch up with the killer.

In January and February 2021, Clua and his team transported 24 water tiger sharks off Saint-Martin and analyzed 25 additional sharks which they caught around St Barts or St Kitts and Nevis.

Because the two women who were bitten had lost a substantial quantity of flesh, scientists saw this as a chance to find the responsible shark. Whenever they dragged a tiger shark out of the water, they turned it backwards, flooded their bowels of water and firmly press the belly to vomit it. A shark is generally “a very easy puker,” says Clua. The team’s examinations revealed no evidence of human remains.

Clua and his colleagues also removed DNA samples from each of the tiger sharks, as well as dead sharks landed by fishermen in St Kitts and Nevis. None corresponded to the elapsed DNA of the injuries suffered by the two women.

But the team has not abandoned. Clua is now awaiting the DNA analysis of mucus samples recovered from a third shark bite that occurred off Saint-Martin in May 2024. If this corresponds to the samples of previous bites, said Clua, it suggested that “could be possible” to catch the permanent shark in the future.

The fact that some specific sharks have developed a propensity for biting people are controversial among marine scientists, although Lucille Chapuis, a marine sensory ecologist at the University of Trobe in Australia, does not quite know why. The concept of problem animals is well established on earth, she says. Land -based land managers regularly face problems, tigers and bears. “Why not a fish?” asks Chapuis. “We know that fish, including sharks, have incredible cognitive capacities.”

However, after having gleaned a range of opinions on the ideas of Clua, some marine scientists rejected the concept of Sharks of problems.

Clua is aware that his approach is divisor: “I have many colleagues – experts – who are against the work I do.”

The greatest decline is scientists who say that there is no concrete evidence of the idea that there are dangerous and biting sharks to the wandering man in the seas. The simple fact of talking about problem Sharks, they say, could perpetuate the idea that certain sharks are hungry for monsters of human eaters like The Beast of extremely non-scientific film jaws.

Clua says that the monster of the jaws and its definition of a problem problem are completely different. A shark problem is neither wild nor extreme; It’s just a shark that learned at some point that humans are among the things he could tackle. Environmental factors, as well as personality, can trigger or worsen such behavior.

In addition to the tiger shark which struck Saint-Martin and St Kitts and Nevis, the study by Clua 2024 detailed the case of another tiger shark involved in several bites at Costa Rica. A third case focused on an ocean laundering shark in Egypt who killed a swimmer by biting her right leg. The same shark then tried to bite the shoulder of one of Clua’s colleagues during a dive.

Toby Daly-Engel, an expert in sharks at Florida Institute of Technology, said that genetic analysis connecting the same tiger shark to two victims of bites in the Caribbean is robust. However, she says that such behavior must be rare. “They are just opportunistic. I mean, these things eat tires. ”

Diego Biston Vaz, fish curator at the Natural History Museum in London, also praises Clua’s work, calling “really medico-legal”. He too underlines that he should not be considered an excuse to demonize sharks. “They are not bad guys; They just try to survive, ”he says.

Chapuis adds that the small number of animals involved in recent studies in Clua means that research does not prove that the problem sharks are real. In addition, while some sharks could learn to bite humans, they wonder if they would continue to do in the long term. People tend to defend themselves well and, given that there are only a few dozen unornowered shark bites recorded in the world each year, she says that there is no data to support the idea that even the most daring sharks benefit from the dead.

In addition, Clua’s plan – to capture problem sharks and translate them into justice – is unrealistic, explains David Shiffman, a marine conservation biologist based in Washington DC. Even if scientists can undoubtedly prove that some specific sharks are responsible for a series of incidents – “which I do not think he has done,” adds Shiffman – he thinks that finding these sharks is not viable.

All the resources used to find problem sharks would be better spent for preventive measures such as rescuers, which could see sharks approaching a very popular beach, explains Catherine Macdonald, conservation biologist at the University of Miami in Florida.

While identifying and removing a shark problem is better than shooting big numbers, she urges people to answer more difficult questions about the coexistence of predators. “For people who don’t want to risk interacting with sharks, I have good news,” she said. “Piscines exist.”

Clua, for its part, intends to continue. He works with colleagues from Saint-Martin to listen to injury to the shark mouth when they occur and to find potential problems.

When asked if he had already experienced a dangerous meeting with a large shark himself, Clua said that in 58 years of diving, this only happened once, while the fishing lance of New Caledonia. Passis underwater, waiting for a fish to appear, he turned his head. “There was an upcoming bull shark [toward] My back, ”he says.

He had the feeling at this moment that he was about to become prey. But there was no violence. Clua looked at the Taureau shark as he turned around and swim.

This story was initially published in Biographic, an independent magazine on the nature and regeneration of California Academy of Sciences.