Aggressive orcas are attacking boats in Western Europe and the increase in sightings of this behavior is confusing scientists.
The latest in a series of reported incidents happened off the coast of Spain in the Strait of Gibraltar on Thursday.
In a video posted to YouTube the crew of a Dutch team competing in a global yacht sailing challenge called The Ocean Race witnessed an orca pod attack their boat.
A killer whale is seen circling Team JAJO's boat skippered by Jelmer van Beek, eventually aiming for the rudder, before others join the attack.
"Oh he's going for it," a crew member is heard saying. "Oh, my god."
The crew made banging noises to scare the orcas off, but not before Team JAJO had fallen from second to fourth place.
"Three orcas came straight at us and started hitting the rudders. Impressive to see the orcas, beautiful animals, but also a dangerous moment for us as a team," Van Beek said in the video. "It was a scary moment,"
It's the latest in a surge of such reports in the region, and the sailors had been warned.
In May, a pod of orcas also severely damaged a sail boat in the area, forcing that crew to call for help to get back to dry land.
Sailing blogger April Boyes said her four-person crew was traveling from Azores to the Strait of Gibraltar when a killer whale got aggressive with their boat. Boyes captured the whole thing on video.
The crew initially turned off the engine after noticing a pod of orcas nearby. But the whales rammed into the rudder and attacked the vessel for over an hour.
The orcas managed to destroy the rudder and pierce the hull of the boat, which began to fill with water.
"The force of [the blows] would spin the helm violently and you could feel the vibration through the deck," Boyes wrote on her blog.
After an hour, Boyes said the crew got ready to install an emergency back-up rudder, but with the orcas still in the water, repairs became impossible.
The crew called Spanish authorities, who rescued everyone onboard and towed the boat back to port. Boyes said the crew continued bailing out the water by hand with buckets.
And the entire time the orcas followed them all the way back to port.
It was the fifth recent report of orcas attacking and even sinking a boat in the region, according to Boyes' blog.
More than a thousand miles to the southwest just one month earlier, yet another boat crew reported a similar incident.
Captain Daniel Kriz was sailing to the Canary Islands, off the coast of Northwest Africa, to deliver a catamaran back in April when he felt a hard hit to the boat.
Video from Kriz shows an orca bashing against a rudder and breaking it off.
"We lost both rudders," Kriz is heard saying.
The orca is seen grabbing the broken rudder in its mouth and swimming away from the side of the boat. Kriz said it only took about 15 minutes for the whale to tear pieces from the vessel.
The company Catamaran Guru wrote on its blog that the boat belonged to one of its clients.
This wasn't the first time Kriz had witnessed a killer whale attacking one of his boats either. In 2020, he says he was in the same situation taking blows from orcas.
Kriz told the blog that the whales seemed to be getting "more strategic," because much like the assault he witnessed three years ago, "he could hear them communicating beneath the boat during a full hour as they pushed the boat around the sea and took its rudder."
"It seems that the orcas in that region between the small island of Spain’s Cadiz and Tangiers, Morocco, have become stealthy pirates over the last 3 years attacking many small boats," the Catamaran Guru blog writes.
Footage of a third aggressive orca encounter with a boat in October 2021 near Sines, Portugal, shows a whale breaking off pieces of another boat in a manner similar to the other reports.
Matt Johnston, who captured the clip, said a pod of orcas circled and rammed into his boat repeatedly, and that even the young whales had learned the behavior.
"The larger pair in the orca pod would batter the boat with their heads, turning it 90 degrees, while the younger pair would attack the rudder," Johnston said.
After calling the maritime police to scare the orcas off, Johnston said he had to have his disabled boat towed into the nearest port.
Multiple sailors who witnessed these incidents have speculated about what might be behind in the surge of reported attacks on boats by orcas in the region.
The behavior has also caught the attention of researchers who call the attacks on boats by killer whales in the Strait of Gibraltar a "disruptive behavior."
Various theories include the idea that some orcas may be triggered after some "aversive incident" such as being struck by a boat propeller, which prompts them to attack rudders.
Marine biologist Alfredo Lopez Fernandez, who co-authored a June 2022 study on orca attacks off the Iberian coast, said a female orca known as White Gladis is thought to be behind some of the incidents, after being traumatized by a collision with a boat.
White Gladis suffered a "critical moment of agony" that flipped a behavioral switch, said Lopez Fernandez.
Others speculate that pressure factors on the local population, learned social behavior, or simply the "natural curiosity of these animals" is behind the unique behavior.
Speaking to Live Science back in May, Lopez Fernandez said that the behavior has spread to younger orcas, such as the ones Johnston witnessed ramming his boat.
"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," Lopez Fernandez said.
In the incident Boyes witnessed off the coast of Spain, she said that although the boat was severely damaged, she does not believe in demonizing orcas.
On her sailing blog. Boyes said more research could be done into these encounters and safe deterrents can be put in place.
"Ultimately we can only wonder but as the behavior becomes more learned, this kind of incident is more likely to happen again and again. Could safe routes be marked on a chart? Perhaps a convoy or recommended sailing hours through the Strait of Gibraltar," Boyes wrote.