Orcas are being sighted in increasing numbers off the coast of Newfoundland this month, and experienced whale watchers have been shocked on three occasions to see the carnivorous predators killing the local minke whales.

Bob Bartlett, of Trinity Eco-Tours in Trinity Bay, has been observing the local waters for more than two decades as a recreational and commercial diver and tour operator. On Tuesday, he and a boatful of whale watchers filmed a pod of six orcas surrounding and devouring a minke, a much more common species.

"It's rare for them to be here, its rare to catch an attack on film or even see one...everything is just so rare, it's unbelievable," Mr. Bartlett said. In 25 years, he's never seen orcas before.

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"They had corralled a minke whale between two or three of these killer whales and there was a vicious deliberate attack ... . You could see blood in the water," he said. "They took the whole of the minke whale by the head and took it underwater."

He said he found the experience exciting, although he had to persuade others in the boat to agree. "Seeing them hunt and take an animal down is just a part of nature. All parts of nature are not necessarily pleasing to the eye or an uplifting experience," Mr. Barlett said.