Watch the moment a French boat off the coast of Portugal comes under attack by a pod of killer whales
Concern is growing that a vengeful killer whale is teaching members of its pod how to ram into boats off the coast of Gibraltar, following reports of a number of attacks involving the animals.
A female orca, known as White Gladis, is thought to be behind the spate of incidents, after being traumatised by its own collision with a boat, researchers believe.
Gladis is now seemingly being joined by other orcas in the attacks, which have sunk three small sailboats in Europe.
Alfredo Lopez Fernandez, a marine biologist at the University of Aveiro, in Portugal, told Live Science the original incident involving Gladis was likely a "critical moment of agony".
He said: "The orcas are doing this on purpose, of course, we don't know the origin or the motivation, but defensive behavior based on trauma, as the origin of all this, gains more strength for us every day."
The most recent of the attacks, which took place on May 4, saw a small sailboat left rudderless in the strait of Gibraltar.
Werner Schaufelberger, captain of the boat, told the German publication Yacht that he witnessed a pattern to the attack, where smaller orcas "shook" the boat's rudder while a larger animal "rammed the ship with full force from the side".
He said: "The two little orcas observed the bigger one's technique and, with a slight run-up, they too slammed into the boat."
Two days before the attack on Mr Schaufelberger's vessel, the Bavaria 46 boat was slammed into by a pod of six orcas off the coast of Morocco.
The incidents seem to follow a style of orcas beginning their attack from the stern of boats, before losing interest once they have successfully disabled it.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...
Mr Lopez Fernandez added: "In more than 500 interaction events recorded since 2020 there are three sunken ships. We estimate that killer whales only touch one ship out of every hundred that sail through a location."
Reports of aggressive orca behavior in the region began surfacing in May 2020, with Spanish authorities then being prompted to introduce a temporary ban on small boats from sailing along a stretch of Spain's Iberian coastline.
The restriction was issued again the following year due to reports of more than 50 boat encounters with orcas.
In 2022, a study published in the journal Marine Mammal Science found that the number of orca attacks on boats had grown.
The report did not settle on a conclusive answer for its findings, but suggested the trend could be due to a loss of prey or disturbances by boats.