- Orcas are ramming into boats and tearing off their rudders, leaving the vessels damaged.
- Experts have two theories about how this may have started and why the behavior is spreading.
Jelmer van Beek's sailing team were in the middle of a race in the Strait of Gibraltar last week, when three orcas appeared out of nowhere.
They "started hitting the rudders," said van Beek, Team JAJO skipper. "Impressive to see the orcas, beautiful animals, but also a dangerous moment for us as a team."
Van Beek's account is a familiar tale. There have been hundreds of reports of orcas engaging in similar behavior, ramming boats with their heads and sometimes ripping off rudders with their teeth, since 2020.
Experts have two very different theories for the behavior, and they still can't agree on which one is more likely. The only thing they are sure of is that the orcas are not out to get humans.
"We know that it's a complex behavior that has nothing to do with aggression (they don't want to eat anyone, nor harm humans) nor revenge (orcas are not resentful)," Alfredo López Fernandez, a scientist studying the whales, told the BBC.
1. The orcas are trying to protect their young
According to the Grupo de trabajo Orca Atlántica (GTOA), a working group of scientists studying the behavior, one motivation for the orcas could be to protect young orcas from dangerous boats.
In this explanation, "one or more individuals had a bad experience and are trying to stop the boat in order to prevent a recurrence," López, a member of GTOA, told the BBC.
The behavior was first spotted in 2020. Initially, there were three whales that were actively engaging with the boats in this way: the so-called White Gladis, and two younger orcas Grey Gladis, and Black Gladis. (Gladis, by the way, is a nickname given to any orca that is seen interacting with a boat.)
The oldest orca, White Gladis, may have suffered some sort of trauma, either by colliding with a boat or getting tangled in fishing lines, or perhaps seeing others being hurt. If that is the case, she is probably the one that would have started the behavior, with others copying her.
"We do not interpret that the orcas are teaching the young, although the behavior has spread to the young vertically, simply by imitation, and later horizontally among them, because they consider it something important in their lives," López told LiveScience.
2. Damaging rudders is fun
Like any other type of dolphin (yes, killer whales are actually a kind of dolphin), orcas are social animals. It's therefore possible that the orcas are simply engaging in playful behavior that's been spreading at the expense of the boats, GTOA said.
While only three killer whales were actively engaging in the behavior in 2020, there are now 14 registered 'Gladises' in the Iberian coast, per GTOA. And they are getting more prolific: in 2020, 52 interactions were reported. In 2021, there were 197. In 2022, 207.
The behavior seems to be spreading beyond the Iberian waters, as one recent interaction was reported as far north as the Shetland islands, off the coast of Scotland.
Orca expert Renaud de Stephanis, who has been carrying out a study to understand the orcas' behavior, thinks this is the most likely hypothesis.
With a team of scientists, de Stephanis has been monitoring the interaction of wild orcas with dummy rudders, the BBC reported. The results of the investigation are due to be published soon, per the BBC.
"We discovered what happens, the killer whales push the rudder with their nose, this makes the rudder break by leverage," he said.
"They're pushing, pushing, pushing – boom! It's a game. Imagine a kid of 6, 7 years, with a weight of three tonnes. That's it, nothing less, nothing more," de Stephanis told the BBC. "If they wanted to wreck the boat, they would break it in 10 minutes' time."
This wouldn't be the first time this has happened. A group of wild dolphins in Australia suddenly started learning to "tail-walk" like trained dolphins, swimming backward with their bodies above water, after a wild dolphin called Billie was kept in an enclosure with trained dolphins while she was recovering from an injury.
The orcas — and the boats — need to be protected
Regardless of their motivation, the behavior has become a problem in the Iberian coast.
With cases rises, sailors have become afraid of mooring their boats in the usual spots, said António Bessa de Carvalho, president of the National Association of Cruises (ANC), Insider previously reported.
Desperate sailors have been trying all sorts of techniques to keep orcas away from the boats, such as throwing sand over the side of the ship, navigating backward, throwing lemons in the water, or hitting dishes and kitchen items to make noise.
Some have even resorted to hitting the orcas or throwing firecrackers and flares at them. None of these techniques has been particularly effective, López told Insider.
GTOA is consulting with the Portuguese government to try to develop "acoustic deterrents" that could keep the orcas away from the boats, López said. The technology is still development and the group hopes they can test it out in the next few months.
For the time being, Lopez said the best way to protect boats is for sailors to "be informed."
"Sailors can consult the website and GT Orcas mobile application (Google Play and Apple Store) to find out about hot spots, be prepared if they sail in those areas, avoid sailing at night and approach the coast, as far as possible," he said.