Scientists believe young orcas are mimicking the behavior of a single female who had a traumatic encounter with a boat in 2020.
Orcas recently launched a coordinated attack against a yacht off of the European coast — and the rest of the population may be copying the behavior, experts worry.
As Live Science reported, one recent killer whale attack occurred on May 4, when a group of three orcas struck a yacht off the coast of Spain in the Strait of Gibraltar.
“There were two smaller and one larger orca,” said skipper Werner Schaufelberger. “The little ones shook the rudder at the back while the big one repeatedly backed up and rammed the ship with full force from the side… The two little orcas observed the bigger one’s technique and, with a slight run-up, they too slammed into the boat.”
The crew was ultimately rescued by the Spanish coast guard, but though they managed to tow the boat to Barbate, it sank at the entrance to the port.
This, however, was not an isolated incident.
Just two days earlier, The Telegraph reported, a pod of six orcas attacked another boat along the Strait of Gibraltar, near Tangier in Morocco.
Skipper Greg Blackburn of Leeds stated that he was combatting “heavy weather” when two large blows struck his boat’s rudder. Shortly after, he realized two large orcas had rammed into it — and then four more showed up.
“Once the main pod turned up, it looked like there was a matriarch with a calf,” he said. “I thought ‘oh dear’ when I saw them. There’s not a lot you can do at that point… I just thought we were in for a ride now.”
Blackburn chose to drop the boat’s main sail to try and make it “as boring as possible,” which seemed to work. The whales lost interest, but not before causing thousands of dollars in damages.
Reports of similar attacks have been continuous since 2020, and experts believe the attacks may all trace back to one singular incident, according to a study from June 2022 published in the journal Marine Mammal Science.
The orca leading these attacks is a large female known as White Gladis, who experts say suffered a “critical moment of agony” after colliding with an entrapment or boat during illegal fishing. At that moment, a behavioral switch flipped for the orca.
“That traumatized orca is the one that started this behavior of physical contact with the boat,” Alfredo López Fernandez, a biologist at the University of Aveiro in Portugal and representative of the Atlantic Orca Working Group, told Live Science.
“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,” he added.
While most encounters with the aggressive orcas have been harmless, there is still growing concern among sailors and scientists. Since 2020, more than 500 interactions have been recorded, but only three ships have sunk as a result.
“We estimate that killer whales only touch one ship out of every hundred that sail through a location,” López Fernandez said.
According to the study, orcas are highly social and easily learn to reproduce behaviors they see others perform. Young orcas witnessing Gladis attacking boats’ rudders, then, resulted in that behavior quickly spreading throughout the population.
“We do not interpret that the orcas are teaching the young, although the behavior has spread to the young vertically, simply by imitation, and later horizontally among them, because they consider it something important in their lives,” López Fernandez said.
Despite the potential risk of attacking the boats, López Fernandez said he believes that the orcas find this behavior advantageous.
Other experts, however, have argued that these attacks may not be aggressive in nature but rather a “fad” — a temporary behavior picked up by a larger group based on the behavior of a few individuals.
“They are incredibly curious and playful animals and so this might be more of a play thing as opposed to an aggressive thing,” Deborah Giles, an orca researcher at the University of Washington and at the non-profit Wild Orca, told Live Science.
Part of the concern, too, is that the Iberian orca population is considered to be critically endangered by the IUCN Red List, with the last census in 2011 recording just 39 Iberian orcas.
Since the encounters began in 2020, four orcas in a subpopulation living in the Iberian waters have died, though their deaths can’t be linked directly to the strange interactions with boats.
After reading about the strange orca attacks off the European coast, learn more about one of the most infamous orca attacks in the world — when SeaWorld’s Tilikum killed his trainer, Dawn Brancheau. Then, read about Lolita, the world’s oldest orca in captivity, and her release back into the wild.