Groups of young orcas have been deliberately ramming into boats since 2020 (Credit: Marineconnection.org/ CC-BY-SA-2.0)

Orcas, also known as killer whales, are the largest members of the dolphin family. The mammals hunt in pods of up to 40 individuals. They are known for their coordinated attacks on marine animals. But the whales rarely pose a threat to humans.

However, since 2020, groups of orcas have intentionally collided with about 700 boats off the coasts of Spain, Portugal, France, and Morocco. The impact has caused at least seven vessels to sink. Experts now believe that this unusual behavior is the result of bored teenage orcas seeking entertainment.

The team, led by Alex Zerbini, came to this conclusion after observing the behavior of a pod of about 15 juvenile whales. They found that the mammals approached the boats slowly. Once close, the whales appeared to simply want to nudge their noses or heads against the rudder. However, these young orcas measure between 9 and 14 feet (2.7 and 4.2 meters) in length. So, even a gentle touch was enough to damage, or sometimes destroy, the rudders.

Spanish officials have banned small boats from sailing in the area where the orca attacks are occurring (Credit: Spanish Ministry of Transport, Mobility, and Urban Agenda)

“There’s nothing in the behavior of the animals that suggests that they’re being aggressive,” Zerbini told The Washington Post. “As they play with the rudder, they don’t understand that they can damage the rudder and that damaging the rudder will affect human beings. It’s more playful than intentional.”

The researchers revealed their findings on May 24, 2024. They attribute the teenage orcas' boredom to the increase in population of their primary food source — the bluefin tuna. In the past decades, when there was a shortage, the mammals spent their entire day looking for the fish. However, now, with plenty of food, they have a lot more time on their hands.

Zerbini and his team are still puzzled about what initially drew the young orcas to the rudder. They speculate the behavior may have been started by a curious individual attracted to the bubbles around the moving vessel. This action may have inspired the others to do the same.

Scientists believe the teenage orcas are just having fun (Credit: Spanish Navy/ CC-BY-SA-2.0)

“Maybe that individual touched a rudder and felt that it was something fun to play with,” Zerbini said. “And, after playing, it began propagating the behavior among the group until it became as widespread as it is now.”

To prevent these encounters, the scientists suggest avoiding orcas when possible. Making banging sounds around the boat may also keep the whales away. Boat owners could replace the smooth rudder surface with bumpy materials. This would make it less fun to "play" with.

“We don’t want to see more boats being sunk, and we don’t want to see people in distress,” Zerbini said. “But we also don’t want to see the animals being hurt. And we have to remember that this is their habitat, and we’re in the way.”

Resources: Washingtonpost.com, LiveScience.com