Within hours of leaving Morocco for Portugal, the crew of the 46-foot sailboat noticed that something was wrong with the rudder. Then someone shouted out what he saw in the shifting waves: “Oaths! Oaths!

Killer whales swam alongside the boat, crashing into the side of the boat and chewing on the rudder, according to her skipper, onboard photographer and video footage of the surprise encounter. For about an hour, the crew reported their predicament to the Spanish Coast Guard and tried to keep their cool.

A small group of killer whales crash into sailboats off the Iberian Peninsula, sinking three from last summer and damaging dozens more.

“This is a reminder of where we are in the food chain and in the natural world,” said one skipper. pic.twitter.com/EvozYwzxXI

— New York Times (@nytimes) May 24, 2023

“There was nothing we could do,” said photographer Stephen Bidwell, who was on a two-day, week-long sailing course when the attack began. “It makes you feel awe and anxiety at the same time,” he says.

The skipper, Gregory Blackburn, said he was struggling to steer the boat when killer whales attacked him, obstructing the helm. “It’s a reminder of where we are in the food chain and in the natural world,” he said.

Eventually the boat managed to return to Tangier, Morocco. However, marine scientists noted the episode on May 2 and said it continues the mysterious behavior of a small group of killer whales off the west coast of the Iberian Peninsula. Killer whales, according to researchers, have sunk three boats since last summer and disrupted the swimming of dozens more.

Killer whales, although they are top predators of sharks and whales, are not generally considered dangerous to humans. These animals, the largest of the dolphin family, are known to touch, push and follow watercraft, but almost never push them, marine scientists say. A small group of killer whales, numbering around 15, began attacking boats across Spain in 2020, with researchers calling the behavior unusual and their motives unclear.

“We know that this is a strange behavior that has nothing to do with aggression,” said Alfredo López Fernández, a biologist at the University of Aveiro in Portugal, who participated in a study published last June on the topic. Killer whales show no signs of wanting to harm humans, he said.

In most cases, killer whales do not change their behavior or make physical contact, according to the Atlantic Orca Task Force, which began tracking direct interactions as well as sightings in 2020.

Since the phenomenon first appeared then, killer whales have been recorded approaching or reacting to ships about 500 times, causing damage about 20 percent of the time, in high-traffic seas off the coast of Morocco, Portugal and Spain, according to the club. .

Killer whales off the Iberian coast are considered an endangered population, with the group reaching the waters of the Strait of Gibraltar every spring from deeper waters and further north towards the coast to hunt tuna. But while it’s common, scientists don’t know how to stop the small group’s recent behavior that has left sailors worried about safety and damage to ships and has drawn the attention of Spanish and Portuguese authorities.

“Every week there’s a new incident,” said Bruno Diaz Lopez, a biologist and director of the Rhinoceros Research Institute who was not involved in last year’s study. “We don’t really know the reason.”

In the most recent example, killer whales collided with a sailboat off the coast of Spain, causing it to sink in the early hours of May 5. Spanish authorities arrived quickly and the four on board were rescued “in good spirits,” said Christoph Winterhalter, president of Hoz Hochseezentrum International, a Swiss company that operated the boat.

University of Aveiro biologist Dr López Fernández said it is possible that three of the boats sank last year because they were prone to leaks or were not equipped to withstand damage, although Mr Winterhalter said he had charter company that “the condition of the vessel was very good”.

Young killer whales

A small group of killer whales, including just two adults, were responsible for the majority of boat interactions, which number about 200 per year and range from the coast of North Africa to France, according to Dr. López Fernandez.

Researchers do not know what is behind this behavior. Some have speculated that this is a “reaction” that may have been caused by an incident between the mammals and the boat, such as entanglement in the line or repetitive behavior by juveniles.

This remains only a theory, although Dr. Lopez Fernandez said the behavior could be passed on between animals in the area. “We know that killer whales pass on their habits to their peers and to subsequent generations,” he said, adding that they also learned through imitation. But because the behavior has only been recorded in this particular part of the population, he said it is unlikely to be replicated by other groups of whales around the world.

In the absence of evidence, and due to the presence of mostly young whales in this group, other scientists express doubts that their behavior is associated with any incident with the boat, and believe that the animals could just … play.

“Maybe they get some kind of reward or entertainment out of it,” says Erich Holt, an orca expert and researcher at the charity Whale and Dolphin Conservation. “And play is part of being a predator,” he explains.

The scientists say that other than for sailors to avoid the area, they know of no other way to prevent killer whales from disturbing boats, as sailing vessels are usually less noisy than most watercraft and therefore more attractive to the animals.