Orcas, or killer whales, are well known for their intelligence and for their remarkable hunting techniques: whether it’s turning great white sharks upside down or working cooperatively to take down large whales. And a population of orcas off the Iberian Peninsula has been gaining attention over the last three years—and causing angst among sailors—by attacking and even sinking boats in the area.
The first recorded attack occurred in the Strait of Gibraltar in May 2020, with dozens of cases recorded since then. Most of the incidents are remarkably consistent, generally involving a small group of whales attacking the rudders of small sailboats before breaking off and swimming away.
In June and November 2022, a pair of attacks caused two boats to sink; earlier this month, a badly damaged boat sank while it was being towed to shore.
Why the attacks may have started
A recent paper in the journal Marine Mammal Science found that the attacks involved nine whales in two groups: a trio, sometimes a quartet, of juveniles; and a mixed-age group led by a mature female named White Gladis. Given that White Gladis was the only mature female involved, the paper’s authors speculated that she had been involved in an accident with a boat and engaged in retributive behavior, which was then copied by the younger whales.
“When it started happening, I did think that maybe a female or her calf had been nicked by a propeller or rudder on a boat, because every single time they seem to go for the rudder. And it's all on sailboats,” says Dan Olsen, a field biologist with the North Gulf Oceanic Society in Alaska.
However, not everyone is convinced that the orcas’ actions have any malevolent intent. Notably, the orcas’ focus is very specifically on the boats; none have shown any interest in the people on board, even when those people have had to scramble into lifeboats when their vessels started sinking.
"I think it's just as reasonable to suggest that they're doing this because they can, because it's fun,” says Hanne Strager, co-founder of the Andenes Whale Center in Norway and author of the recently published book The Killer Whale Journals.
A new form of play
Strager spoke to a biologist who was on board the boat that sunk in November, "and he said, ‘We didn't feel any aggression.’ And, to me, that's actually a strong testimony. Because I think when you are interacting regularly with animals, and you're used to reading them, you can feel an aggressive intent, and they didn't.”
If the orcas are indeed playing, it may suggest that, in time, the boat attacks could end when the whales get bored. Orca populations around the world have been observed engaging in a new behavior for no obvious reason than that they appear to enjoy it and then, just as suddenly, dropping it and moving onto something else. Orca researchers call these play routines “fads.”
Olsen, for example, has observed killer whales off Alaska playing with a piece of kelp for an hour: dragging it around on their fins, dropping it, circling back around and then picking it up in their teeth and swimming around with it some more. Strager has observed similar behaviors in orcas off the coast of Norway.
“For a while we saw them playing around with jellyfish,” she says. “They would swim with them on their snouts and would try to keep them on for as long as possible.”
There's no benefit from this behavior, and the orcas were not eating the jellyfish, Strager notes.
“Sometimes we also see them whack little auks … small Arctic birds, they just lie on the surface of the sea to rest, and the orcas will come and whack them,” which she thinks is also a form of play.
Olsen questions whether we will ever truly understand the motivation behind the behavior, or whether we even really have the capacity to figure it out.
“The whale brain has been evolving separately for 50 million years,” Olsen says. “It’s hard to get a whale into an MRI, we don't even know which parts of the brain are dedicated to which activity. It's hard enough for us to explain behavior in humans and in primates that are closely related to us.”
Only this population has shown any interest in attacking boats, and it is a small one: the Marine Mammal Science paper cited an estimate of just 39 individuals.
The population in this region is under threat, says Strager, from tuna fishing, pollution, noise and, indeed, ship strikes.
“They are among the most polluted marine mammals in the world, so their breeding success is not good. It’s a very stressful environment for them,” she says.
And now, added to the existing stressors is the prospect of retaliation.
“Now they are becoming feared in the area,” notes Strager, “and there are reports of people suggesting you should pour diesel on top of them if they attack your boat, that you should put firecrackers in the water or ignite dynamite. I understand if people are afraid. But it's really a very dangerous situation for the killer whales.”
One local group, the Atlantic Orca Working Group, catalogues interactions between whales and boats so that sailors can learn which areas to avoid.