For the last several years, we have been posting about orca attacks on yachts and fishing boats in the Strait of Gibraltar and the Iberian peninsula. Pods of orcas have been ramming sailboats and often grabbing their rudders and keels, and have caused significant damage, most often to the boat’s steering. In the last three years, there have been close o 500 such attacks and at least three sailboats have been sunk.

What has prompted the attacks remains a mystery to scientists. 

Until recently, the attacks were confined to the coastal waters of Spain and Portugal.  Now, the Guardian reports that an orca repeatedly rammed a yacht in the North Sea off Shetland earlier this month.

Dr. Wim Rutten, a 72-year-old retired Dutch physicist, and experienced yachtsperson, was sailing solo from Lerwick to Bergen in Norway. He was fishing for mackerel, with a single line off the back of the boat, when the orca suddenly appeared in the clear water, and hit the stern of the seven-ton boat.

“I said: ‘Shit!’” Rutten, who said he had heard about the “Portuguese accidents”, told the Guardian. The whale hit again and again, creating “soft shocks” through the aluminum hull.

“What I felt [was] most frightening was the very loud breathing of the animal,” he said. The orca stayed behind the boat “looking for the keel. Then he disappeared … but came back at fast speed, twice or thrice … and circled a bit.

Most surprising to researchers is the fact that what seems to be learned behavior has appeared nearly 2,000 miles (3,200km) from Gibraltar. Dr. Conor Ryan, a scientific adviser to the Hebridean Whale and Dolphin Trust, who has studied orca pods off the Scottish coast, said: “I’d be reluctant to say it cannot be learned from [the southern population]. It’s possible that this ‘fad’ is leapfrogging through the various pods/communities.”