Scientists suggest that orcas that ram boats may be using yachts as target practice toys

Scientists have a new theory as to why killer whales ram yachts on the Iberian Peninsula — the boats serve as training targets to learn how to hunt their favorite food.

When young Iberian killer whales (Orcinus orca) began hitting and sinking boats in 2020, experts wondered if it was revenge, coincidence, or simply cool thing to do. However, a new theory suggests that young orcas may be using boat rudders as targets to practice hunting bluefin tuna (Thunnus vulgaris).

Since 2020, the sailing community has understandably been very interested in where the predators are. “We saw this as a great opportunity for science,” said the study’s lead author Bruno Diaz Lopezdirector of the Bottlenose Dolphin Research Institute (BDRI), told Live Science. The team realized they could use citizen science to gather accurate data on the distribution of the killer whale population. “Boats aren’t going to lie to each other because this is a pretty serious issue,” he said. Nearly half (47%) of the 597 survey records of killer whale occurrences were related to ship interactions.

Using this data, the team created computer models of killer whale movements to fill in the gaps in knowledge about their seasonal movements. Their models showed that killer whales and tuna are driven by the same environmental factors, meaning that knowing where the tuna are gives a good idea of where the killer whales will be. They found seasonal changes in the killer whales’ preferred habitats that matched the tuna’s migrations.

Related: A really big shark was swallowed by another huge shark in the first known case of its kind

The results were published on June 18 in the journal Ocean and Coastal Management.

Orcs are highly specialized predators, and different communities prefer different prey, depending on what is the most abundant food available. Iberian killer whales “really rely on tuna,” Díaz López said.

Atlantic bluefin tuna is no longer endangered thanks to protection measures against overfishing. Their recovery makes it easier for the Iberian killer whales to find food, giving them more free time. “If you eat well, you have more time to play,” Díaz López said.

A boat with a damaged rudder after being rammed by orcas in May 2023. (Photo credit: Jorge Guerrero/Getty Images)

And that art can give them a chance to practice useful skills. Killer whales need to work together to catch tuna, because the fish can weigh hundreds of pounds, swim in large schools and are among the fastest fish in the sea.

To isolate a single tuna and move it away from the group’s protection, the orcas ram, Díaz López said. “Maybe one orca will strike, and then the other one will strike again,” he said. Once the orcas isolate a single tuna, they tire it out and drive it toward shallower waters, where it’s easier to catch.

Based on reports of killer whale behavior toward sailboats, Díaz López believes the orcas are doing something similar to hunting: repeatedly ramming a fast-moving rudder before trying to bite it. “Playing is learning,” he said. “If you have a dog and you use a toy, the dog is learning the hunting technique.”

Erich HoytA researcher with the charity Whale and Dolphin Conservation, who was not involved in the study, agrees that the orcas are likely playing. The interactions are most likely due to “normal predatory curiosity leading to playful behavior,” he told Live Science in an email. But he’s not convinced the boats are just target practice.

“I don’t think the killer whales are playing with the controls just to improve their tuna-hunting skills,” he said. “I think their play is more like children’s play, without a specific goal but which ultimately helps develop cognitive and physical skills.”

To prevent further negative encounters, Hoyt recommends boaters monitor the killer whales’ movements and stay away. “The more often the activity occurs, the more it reinforces the continuation of the activity,” he said.

He believes such behavior is a phase that will eventually fade away. “In our limited experience, we have seen that fads fade over time,” he said.