In just over a week, bathers have witnessed several specimens of blue sharks or blue sharks in the waters of the Costa Brava. The first case was on the Porbou beach, on July 16, and this Monday two more specimens were sighted on the Gran beach in Port de la Selva, which was evicted for half an hour. Shortly after, a surfer observed the species near the S’Arnella lighthouse, in the same municipality.

The Costa Brava is not the only area of ??the Mediterranean where blue sharks have been seen this summer. On the coast of Menorca, Alicante and Valencia they have also been seen very close to the coast. In none of the cases has the life of the bathers been endangered, although their presence has generated some scenes of panic.

Experts do not know why more blue sharks are being seen in shallow water this summer. “This year there are closer to the coast, something that is rare and unusual,” says Lluís Cardona, a biologist from the University of Barcelona (UB), who rules out that there is no cause-effect relationship with the high water temperature. Currently, depending on the area, it is around 25 or 26 degrees Celsius, a figure higher than last year.

Unlike the whales that come close to the coast during their migration from the southern Mediterranean to the Gulf of Leon in spring, this is not a common behavior of the blue shark. Typically, this species is found offshore. “It is a fish from oceanic waters, which during the day can swim below 200 meters and at night rises to the surface.”

Those that were seen in Portbou were rather small animals, measuring one and a half meters. They can reach 3.5 meters, although the average size of those caught in the Mediterranean is around 1.80 meters, according to the biologist.

They are solitary animals, they do not swim in groups and they feed mainly on small fish and squid. “They don’t eat dolphins or people,” says Cardona, who appeals to bathers so that if they find any specimens in their waters, they don’t panic.

“If you see it, calm down, get away from the animal and notify the lifeguard,” he explains. The blue shark, with a 20 centimeter mouth, can bite only if she is startled. “So it cannot be ruled out that she will bite, but it is highly unlikely that she will attack,” she says.

One of the hypotheses of its approach to land is that it has some physical problem. But of all the specimens sighted so far, only in one case was the lifeless body of the animal located a few days after being seen. “When an oceanic animal has problems, it can end up on the beach like a log or plastic, because it doesn’t swim against the current,” Cardona explains.

The abundance of blue sharks has been declining since the 1970s due to fishing. That year, surface longline fishing was introduced in Spain, targeting swordfish and tuna, but many blue sharks also began to be caught, which caused their decline.