Orcas that have been bumping boats in Iberian waters for four years are likely just bored teenagers with too much time on their flippers, experts say.
A report published May 24 found that orcas (Orcinus orcas) involved in a string of boat-ramming incidents in southwestern Europe are spending less time hunting and more time exploring new games now that populations of their favorite prey have rebounded. At least 673 interactions with boats since May 2020, six of which caused the boats to sink, may have resulted from these orcas having more free time, according to the report.
Something about the rudder on the underside of boats appears to attract orcas, particularly young members of the pod that are generally more curious. Whatever it may be, "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," co-author Alex Zerbini, a senior research scientist at the University of Washington who chairs the scientific committee of the International Whaling Commission, a global body tasked with whale conservation, told The Washington Post.
"There's nothing in the behavior of the animals that suggests that they're being aggressive," Zerbini said.
Fifteen orcas are known to interact with boats, most of them young and teenage males, according to the report. These orcas are a subset of the critically endangered Iberian population, which is thought to number fewer than 40 individuals.
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A video released May 17 by the Spanish group Conservation, Information and Research on Cetaceans (CIRCE) shows how the orcas break rudders by nudging them with their noses and heads. It remains unclear how the behavior started, but scientists have largely discarded previous suggestions it could be motivated by revenge and now believe it is more likely related to play.
An orca may have initiated the behavior after touching the rudder of a boat and feeling it was fun to play with, Zerdini said.
"It's a very dangerous game they're playing, obviously," co-author Naomi Rose, a senior scientist and marine mammal expert at the Animal Welfare Institute in Washington D.C., told The Washington Post. "But it's a game."
Iberian orcas playing with boats could be linked to a rise in the abundance of Atlantic bluefin tuna (Thunnus thynnus), their favorite food, according to the report. Bluefin tuna were previously the target of rampant overfishing, with numbers nosediving to critical levels in the late 1990s and early 2000s, but populations in the eastern Atlantic Ocean and Mediterranean Sea have largely bounced back over the past 15 years.
The recovery of bluefin tuna stocks could mean orcas "have all this leisure time on their hands because they don't have to eat every fish they find," Rose said. Ramming boats may be trending in a similar way to previous fads — which include orcas wearing dead salmon as hats and tossing baby porpoises around — but there isn't enough data to determine exactly how the behavior is spreading within the population, according to the report.
Ramming boats may be a game to orcas, but it certainly isn't for mariners. In the report, scientists outlined measures to limit the "satisfaction or reward" orcas gain from interacting with boats. These measures include steering clear of orcas when possible, fitting boats with rudders that are abrasive or bumpy rather than smooth and making banging sounds in the water.
"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."
