Killer whales ramming boats in Spain and Portugal leave scientists baffled

Several sailors have sent out distress calls after encounters with aggressive orcas. Photo / Getty Images

Killer whales have been ramming yachts and boats and injuring sailors off the coast of Portugal and Spain.

Scientists cannot explain what is causing this sudden change in behaviour by the orcas, which have now caused damage to several boats in the last two months.

The Guardian reports that the latest incident happened off the coast of A Coruña in northern Spain, where a 36ft boat was rammed by an orca at least 15 times.

Victoria Morris was crewing in Spain on the boat when the orca rencounter took a turn for the worse.

"The noise was really scary," she said. "They were ramming the keel, there was this horrible echo, I thought they could capsize the boat. And this deafening noise as they communicated, whistling to each other. It was so loud that we had to shout." It felt, she says, "totally orchestrated".

Two boats have reportedly also lost part of their rudders and crew members have been injured in the different incidents.

Alfonso Gomez-Jordana Martin, a 31-year-old from Alicante, was crewing a delivery boat near Barbate when orcas started bumping the rudder of the 40ft craft.

"Once we were stopped, they came in faster: 10-15 knots, from a distance of about 25m," he told the Guardian. "The impact tipped the boat sideways."

Vessels have been radioing the coastguard for help reporting attacks from killer whales, from Gibraltar to Galicia.

Experts who have been studying a small orca population off Gibraltar say it is normal for the animal to follow boats but the instances of ramming and the attacks are not common.

According to the Guardian, scientists are baffled about what could be causing this sudden wave of aggression, calling it "highly unusual" and "concerning".

Spanish maritime authorities have issued warnings for crews to keep their distance.