weird science

Why Do Orcas Keep Messing With Boats in Southern Europe?

Photo: Shutterstock / riekephotos/Shutterstock / riekephotos

On Thursday morning, a small group of killer whales battered the 66-foot sailing yacht Mustique off the coast of southern Spain, doing enough damage — including puncturing the hull and breaking the rudder — that the crew had to call in a maritime rescue and the vessel had to be towed to port for repairs. It was the second time in less than a week that such an encounter was reported in the area, and the latest in a baffling series of seeming attacks on boats by the animals in or near the Strait of Gibraltar. On May 5, the 50-foot sailing yacht Alboran Champagne sank after being struck by orcas the previous night — the third vessel in the last three years to go under after a run-in with some unruly Orcinus orca locals.

It’s still not clear why these highly intelligent, innately curious mammals — who have apparently been learning the behavior from each other — are going after the boats or whether the damage is even intentional. Some scientists have theorized that the behavior may be a kind of self-defense that originated with a single female orca after a traumatic encounter with a boat. It’s also possible it’s just a fad that has become popular with some of the orcas and will eventually fall out of fashion — a phenomenon scientists have previously observed among orcas and other members of the dolphin family.

Since the first known incident in May 2020, Grupo Trabajo Orca Atlántica (the Atlantic Orca Working Group) has tracked more than 500 cases in which members of the Iberian orca population reacted to or harassed boats in some way. But only a very small percentage of these encounters have involved physical contact, and only a handful of animals in this small endangered population of orcas appear to have engaged in the abnormal behavior — many of them juveniles. When the encounters have turned physical, the orcas have typically targeted the boats’ rudders and have sometimes bumped or rammed the boats themselves. In those instances, less than 20 percent of the vessels have been disabled as a result; and everyone aboard was safely rescued afterward.

These animals are not acting like horror-movie monsters, in other words, nor is their abnormal behavior deserving of some of the sensational news coverage the incidents have received in recent weeks. At the same time, the alarming encounters have become a routine hazard for people who sail in the area, some of whom have been using a Facebook group called Orca Attack Reports and other online forums to share experiences and advice on how to avoid or limit close encounters with the mammals.

GTOA scientists believe just 15 individual orcas out of a population of more than 50 in the area are taking part in the incidents, and that the behavior may be something invented out of the blue by the animals or might be a kind of reaction to previous encounters with vessels. Scientific American reports:

In a study published in June 2022 in Marine Mammal Science, [GTOA researcher Alfredo López] and his colleagues cataloged 49 instances of orca-boat contact in 2020 alone. The vast majority of the attacks were on sailboats or catamarans, with a handful involving fishing boats and motorboats. The average length of the vessels was 12 meters (39 feet). For comparison, a full-grown orca can be 9.2 meters (30 feet) long …

In 2020 researchers observed nine different individual killer whales attacking boats[.] The attacks tended to come from two separate groups: a trio of juveniles occasionally joined by a fourth and a mixed-aged group consisting of an adult female named White Gladis, two of her young offspring and two of her sisters. Because White Gladis was the only adult involved in the initial incidents, the researchers speculate that she may have become entangled in a fishing line at some point, giving her a bad association with boats. Other adult orcas in the region have injuries consistent with boat collisions or entanglement, López says. “All this has to make us reflect on the fact that human activities, even in an indirect way, are at the origin of this behavior,” he says.

Other scientists are skeptical that a traumatic experience prompted the behavior. Orca expert Erich Hoyt told the New York Times that it was likely the animals involved in the incidents are “getting some sort of reward or thrill from it,” since “play is part of being a predator.”

Another marine mammal expert, University of St. Andrews’s Luke Rendell, notes at the Conversation that the past-trauma theory is plausible but unlikely to be something anyone will ever be able to prove:

Notions of collective self-defence in cetaceans (aquatic mammals including whales, dolphins and porpoises) are far from outlandish. We have accounts of sperm whales rising to each other’s defence when orcas attack, for example. Solidarity is a more subjective issue, and we don’t have access to the internal mental states of these animals to really understand whether this is going on … It is not impossible that these orcas perceive their own common aggressor in us — but it is also entirely possible they have no such concept.

Orca Behavior Institute director Monika Wieland Shields explained to NBC News that appearances can also be deceiving. “I think it gets taken as aggression because it’s causing damage, but I don’t think we can say that the motivation is aggressive necessarily,” she said, adding that there is no evidence of orcas seeking payback on humans:

We know their brains are wired to have really complex emotions, and so I think they could be capable of something like anger or revenge. But again, it’s just not something that we’ve seen any examples of, and we’ve given them plenty of opportunities throughout the world to want to take revenge on us for various things. And they just choose not to.

In addition, scientists are worried the population of Iberian orcas, which is already critically endangered, will face retaliation from humans over the incidents, as Andenes Whale Center co-founder Hanne Strager emphasized in an interview with National Geographic:

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. … Now they are becoming feared in the area, 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.

This post has been updated.

Why Are Iberian Orcas Targeting and Sometimes Sinking Boats?