Orcas have attacked and sunk three boats off the coast of Europe since 2020, and scientists think the behavior is spreading among the population through social learning, reports livescience.com.
The orcas, also known as killer whales, have mainly targeted sailboats, making a beeline for the rudder and piercing it with their teeth. Experts believe that a traumatic event may have triggered a change in the behavior of one orca, which the rest of the group has learned to imitate.
The first reports of aggressive encounters with orcas off the Iberian coast began in May 2020 and are becoming more frequent, according to a study published in June 2022 in the journal Marine Mammal Science.
Most encounters have been harmless, but three boats have sunk after being damaged by orcas. The latest incident happened on May 4, 2021, when three orcas struck a yacht in the Strait of Gibraltar and sank it at the port entrance.
Orcas are social creatures that can easily learn and reproduce behaviors performed by others, according to the study.
In some cases, witnesses have reported seeing a mother orca teaching her calf how to charge into the rudder. Orcas have also been observed imitating each other’s techniques and taking turns to attack a boat.
Researchers think that a traumatized orca may have initiated the assault on boats after a “critical moment of agony” and that the behavior is spreading among the population.
The orca, named Gladis by researchers, was severely injured by a harpoon in 2019 and may have associated boats with pain and danger. Gladis was part of a group of orcas that frequented the Strait of Gibraltar and interacted peacefully with boats for years before the attack.
The study suggests that Gladis’s experience may have influenced her behavior and that of her group members, who may have perceived boats as a threat or a challenge.
The researchers also propose that the orcas may be expressing frustration or boredom due to changes in their environment, such as reduced food availability, increased boat traffic, or noise pollution.
The researchers hope to better understand the motivations and consequences of the orcas’ behavior and to find ways to prevent further conflicts with boats. They also urge people to respect the orcas’ space and avoid disturbing them.