Why are killer whales going 'Moby-Dick' on yachts lately? Experts doubt it's revenge

The attacks started suddenly and inexplicably in the spring of 2020—pods of endangered killer whales began ramming yachts and fishing boats in European waters, pushing some off course and imperiling others.

Since then, there have been more than 500 reports of orca encounters off the Iberian peninsula. In most cases, the financial and structural damage has ranged from minimal to moderate: Boats have been spun and pushed, while rudders have been smashed and destroyed. Three vessels have been so badly mauled, they've sunk.

As the encounters continue, shaky video captured by thrilled and fearful seafarers has ignited a global internet sensation, while experts have struggled to explain the behavior and its timing. The seemingly militant whales have also won over a legion of adoring fans—many transfixed by the notion that the mammals are targeting rich people, and exacting revenge for all the wrongs humanity has waged on their species and their ocean home.

Others wonder if the unusually large pods of multi-ton cetaceans now appearing off the coasts of San Francisco, Monterey and Nantucket, Mass., may soon follow suit.

Despite such rampant speculation on social media, most killer whale scientists have offered a very different interpretation. The Moby-Dick "revenge" narrative for the behavior is highly unlikely, they say.

"That just doesn't sit right with me," said Deborah Giles, an orca researcher at the University of Washington, Seattle, and director of Wild Orca, a Washington-based conservation research organization.

She noted that despite the long history of orcas being hunted by whalers—and more recently marine parks—these top ocean predators have typically demonstrated a lack of aggression toward humans. There are no verified instances of orcas killing humans in the wild. The only deaths have occurred in marine parks and aquariums, where animals taken from the wild and forced to perform for humans in small tanks have attacked their trainers.

"So, I just don't really see it as an agonistic activity; I just don't see it going down like that," said Giles, who has studied killer whales in the Pacific Ocean, Puget Sound and the Salish Sea for nearly 20 years.

Instead, she thinks the animals are engaging with boats because the vessels are "either making an interesting vibration or sound, or maybe it's the way the water moves past the keels that is intriguing to these animals."

The scientific literature is rife with anecdotes and research showing high cognition, playfulness and sociality in the species known as Orcinus orca—and examples of what appear to be the cultural transmission of new behaviors, either via teaching or observation.

In 1987, a female orca in the Pacific waters off the coast of North America was spotted sporting a dead salmon on her head. Within weeks, individuals in two other pods also began wearing fish hats. The trend lasted a few months, and had fizzled out within a year.

In South Africa, the killing of white sharks appears to be growing in popularity among a resident group of killer whales in the waters near Cape Town; Giles has watched a local trend of "phocoenacide"—or porpoise killing—grow among a group of whales off the San Juan Islands.

In both cases, the behavior does not appear to be for the purpose of feeding, said Giles. The orcas do not eat the dead animals. For instance, in the case of the porpoises the killer whales played with them—bandying them about, sometimes surfing with them, other times carrying them on the orcas' pectoral fins—until the porpoises drowned, at which point they were abandoned, she said.

"Fads" are not unique to orcas. Other animals, including primates and other cetaceans, have also been observed to adopt new behaviors, which then spread through a social group.

Susan Perry, a biological anthropologist at UCLA, has studied a population of capuchin monkeys in Costa Rica where she has observed and demonstrated the cultural transmission of novel behaviors, including "eye poking"—in which one monkey slips its finger "knuckle deep" between the eyelid and the bottom of another monkey's eyeball.

But the idea that the whales' behavior is a response to trauma has gripped many—including the researchers who most closely study this population and first documented the behavior.

In a paper published last year, a team of Portuguese and Spanish researchers suggested the behavior seen in the Strait of Gibraltar orcas could have been triggered by a variety of causes, including trauma.

Alfredo López Fernandez, a killer whale researcher with GT Orca Atlántica, a Portuguese conservation research organization, said it is impossible to know how it started, or which whale or whales may have initially instigated the attacks.

He listed several adult females as the possible original perpetrators—then teaching or showing others how to participate.

There is White Gladis, who seems to be present in most of the attacks; Gladis Negra, who was observed to have injuries in 2020, possibly from a ship strike; and Gray Gladis, who in 2018 witnessed another whale get trapped in fishing gear.

Gladis is a name given to all orcas in the pod that interact with boats; it comes from Orca gladiator, an early nickname given to these boat-jouncing killer whales.

"All of this has to make us reflect on the fact that human activities, even in an indirect way, are the origin of this behavior," he said.

For Cal Currier's part, he thinks the whales are entertaining themselves.

On June 8, as the 17-year-old Palo Alto High School senior sailed through the strait with his father, James, 55, and brother, West, 19, their 30-foot sailboat was accosted, and spun in circles.

The rudder was battered, and the trio had to be towed to shore in Spain. "They were playing," Currier said.

He said when they pulled in, they were told roughly 30 other boats were ahead of them in line for repairs; half were damaged by the killer whales. He said there were no bite marks on the rudder, and he did not sense aggression from the whales.

For Giles, the Washington killer whale researcher, her biggest concern is that the longer the whales continue this behavior, the more likely it is they'll get injured or suffer retribution at the hands of humans.

She's hoping authorities in the region will consider non-traumatic hazing techniques—such as instructing boats to play or make sounds that irritate the whales—to get them to stop. She said studies have shown orcas don't like the calls of pilot whales, and will generally swim away if they hear them. Loud banging sounds, such as hitting a large, metal oikomi pipe underwater, can also be effective.

"Anything that might irritate them, make them lose their interest or swim away," she said.

Currier said he wasn't too rattled by the whole experience—unlike his dad and brother, who were "scared for their lives."

The trio have since sold the boat and intend to spend the rest of the vacation on dry land.

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