Why Are Orcas Ramming Boats?

Since about 2020, people have been trying to figure out why orcas keep ramming sailboats near the Iberian Peninsula, including in the Strait of Gibraltar. Sailors hoping to protect themselves have tried everything from different-color hull paint to blasting heavy-metal music, only to be continually frustrated by the behavior of the apex predators.

Bruno Díaz López, director of the Bottlenose Dolphin Research Institute, thinks his team has finally figured out what the orcas are doing. His researchers combined spacial distribution models with information from boaters to demonstrate that the orcas are practicing to become better hunters of Atlantic bluefin tuna. The findings were published recently in the scientific journal Ocean and Coastal Management.

“We tried to understand their movements better,” Díaz López told Soundings. “We knew they were going in the spring and summer to the Strait of Gibraltar, but after this study, we found that they move through an area that is much larger.” That was a key finding, he says—not only that the orcas are moving through a bigger region, but that this particular population of orcas is moving to chase the bluefin tuna.

“The populations that we know around the world are highly specialized,” he says. “They choose their prey. In Canada, for instance, it’s the salmon. It depends on the population. They show preferences. In this population, they are focused on the bluefin tuna. All their behavior and movements are linked to that species of fish.”

In learning from boaters about past encounters, the researchers gleaned not just that the orcas have been targeting sailboats, but also that they seem to be homing in on the rudders. As one sailor described to CNN in 2023: “We were suddenly surprised by what felt like a bad wave from the side. That happened twice, and the second time we realized that we had two orcas underneath the boat, biting the rudder off. They were two juveniles, and the adults were cruising around, and it seemed to me like they were monitoring that action.”

Descriptions like that one, and others from boaters, led the researchers to realize they recognized the type of behavior the orcas were displaying. “In observing the behavior of the juveniles hunting the tuna, and listening to the sailors describe the damage to their rudders, we understood the connection,” he says. “It’s play. It’s a game that’s linked to training. It’s the same kind of behavior when they hunt tuna.”

The orcas, he says, hit the sailboat’s rudder and bite it. That’s also how they hunt the bluefin tuna. The orcas have to cooperate in a hunt, because bluefin tuna are fast—able to move at about 40 knots. The tuna also swim in schools, so the orcas have to separate one of the fish from the school in order to catch it. “It’s the same as the lions and gazelles,” he says. “The lions have to cooperate. With the orcas, it’s very similar. If you have time to play when you are young, you will be more efficient when it’s time for the hunt.”

The orcas are not confused about what they’re doing, he says. They know the boat’s rudder is not food, just as a dog knows a tennis ball is not dinner—but just like the dog, the orca still wants to play with the toy anyway. “In sailboats, the rudder is much larger than in the motorboats,” he says, adding that in almost all of the more than 100 examples the team studied, the whales targeted sailboat rudders. “They can almost take the rudder completely from the boat. They can bite it. The material is quite soft.”

Boaters who want to take preventive action might think that installing a top-end fishfinder to look for bluefin tuna would be a good solution, but Díaz López says no. The tuna move too fast, and the orcas can be unpredictable. Instead, he says, work with other boaters to compile information via social media and maritime apps. The number of incidents in the past year was lower, he says, because boaters were alerting one another when they knew where the orcas were located.

“What I suggest to friends of mine is to keep well-informed,” he says. “There are now so many channels and apps from so many groups on social media where people are keeping in touch about where the orca groups are present. If you know they are in the area where you are sailing, be careful. They tend to be in water deeper than 40 or 50 meters. If you can sail in shallower waters, you will be safer.”

He doesn’t recommend a specific social media group or app to follow, but instead encourages sailors to think about orca safety in this region the way they think about the weather. “I sail, so I check the weather, and usually I check three or four apps to make sure the conditions are good,” he says. “I suggest that boaters do the same thing with different channels about the orcas.”

The best bet sailors can make, he says, is to stay away from the orcas in the first place. “Maybe your trip gets a little bit longer, but it’s safer than to go across an area where the orcas may be present,” he says. “If you spot them, switch on the engine, put down the sails and move away as quickly as possible.” 

January 2025