Insights Into a Disruptive Behavior of Iberian Killer Whales (Orcinus orca) With Boats: Perspective From Multiple Interactions With a Research Vessel

Abstract

Multiple killer whales of the Iberian subpopulation interact with boats by establishing physical contact through bumping and pushing. First reported broadly in 2020, this disruptive behavior has since caused considerable damage to hundreds of vessels. Even though there are various hypotheses for what drives these interactions, the cause and purpose of this behavior are not yet understood. Here, we report on seven events between 2018 and 2025 where killer whales made direct physical contact with a research vessel in southern Portugal. Out of 26 identified individuals, 8 interacted with our rigid-hulled inflatable boat: 2 adult females and 6 juveniles of both sexes, from 5 recognized matrilines. Notably, one juvenile interacted on two occasions. Underwater footage revealed a variable nature of interactions, ranging from displays of curiosity to agonistic behaviors. In all encounters, feeding/foraging was observed. We documented an interaction that predates official reports by 2 years and recorded a new individual participating in this behavior, highlighting its continued spread through social transmission. In our observations, keeping the vessel stationary did not reliably decrease interaction intensity, while accelerating caused apparent loss of interest. However, improved mitigation measures are needed to prevent harm to humans and killer whales, securing long-term coexistence.