Swimmers and sunbathers in France and Spain have been warned to take caution by the sea following shark scares.
Last Wednesday, swimming was banned at popular beaches in the south of France and the Mediterranean island of Corsica following a number of blue shark sightings.
This came after the Ocata, Ponent, Masnou, Descàrrega, Bellamar, and Pla de l’Os beaches near the Spanish city of Barcelona were closed off, after three small blue sharks were spotted by lifeguards, Sky News reported. The animals were believed to have been between 1m to 1.5 m long.
At the time, Hasina Ahmad of the Red Cross said: "Three sharks of about one to one and a half meters in length were spotted near the area where people swim up to two meters from the shore, very close. They could be seen from the beach."
While beaches in both countries have re-opened, French officials lifting their ban on Monday said swimmers should remain vigilant.
Only nine attacks on humans by blue sharks have ever been recorded, with the majority of those against divers who were spearfishing while carrying dead fish.
But experts are concerned by how close the sharks are swimming to the shore.
Richard Peirce, chairman of the Shark Trust, told the Telegraph that blue sharks are a “very common” species in the Mediterranean and North Atlantic, but usually swim over six miles out to sea.
Mr Pierce explained that the sharks could be attracted by fishing boats discarding unwanted catch. The diet of the Blue Shark consists mainly of small fish and squid, but it has been known to eat smaller sharks, and sea birds.
"If I had a beach full of people I would probably close it. If they follow a fishing boat in they are in the feeding mode, and the last thing you really want them to do is swim around people," he said.
Alexis Wargniez, a shark researcher, told the newspaper that the blue sharks were unlikely to be aggressive, but that they “may defend themselves if they're stressed.”