A study by the Association for the Investigation of the Marine Environment (AIMM) documents seven episodes of physical interaction between Iberian killer whales and a research vessel, recorded between 2018 and 2025 off the southern coast of Portugal. The results, published in the scientific journal Marine Mammal Science, reveal behaviors of variable intensity and present evidence of social learning among some of the observed animals.
In the seven encounters, 26 orcas were identified, eight of which established direct contact with the vessel, predominantly juveniles. Underwater footage captured behaviors ranging from light touches to pushes strong enough to spin or tilt the boat.
One of the episodes occurred in 2018, two years before interactions between orcas and boats began to be widely reported on the Iberian Peninsula. According to the researchers, the record contributes to knowledge about the chronology of this behavior, though it does not allow establishing a direct relationship between the episode and subsequent events recorded.
The study also identified signs compatible with social learning. Some individuals who had been observed in earlier encounters without touching the vessel established contact with the boat on later occasions.
Motivations remain to be clarified
The reasons that lead some orcas to approach and physically interact with boats continue, however, without a definitive explanation. The researchers consider that curiosity, play, or responses to disturbance may be among the possible explanations for different episodes, but emphasize that the available data do not allow attributing a single cause.
“Our observations show how these interactions can be variable. We observed behaviors ranging from curiosity to much more intense interactions, and even intriguing behaviors, such as approaching the vessel with prey in the mouth, seemingly showing them to us,” says Joana Castro, president and researcher of AIMM.
The researcher adds that the objective now is to better understand the origin of these behaviors and to find ways of safe coexistence between the orcas and human activities at sea.
The authors also highlight that the results should be interpreted with caution, since the study is based on a small number of episodes involving a semi-rigid research vessel. The observations do not allow generalizing the behaviors identified to the entire Iberian population of killer whales.
The investigation is of particular relevance for the conservation of this population, classified as Critically Endangered. Monitoring interactions with boats could contribute to a better understanding of these animals’ behavior and support measures aimed at reducing conflicts and disturbances in their habitat.
The study was conducted by AIMM researchers and other institutions and was published under the title Insights Into a Disruptive Behavior of Iberian Killer Whales (Orcinus orca) With Boats: Perspective From Multiple Interactions With a Research Vessel.
