North Pacific right whales were once abundant between B.C. and the Bering Sea before they were hunted to near extinction before the 20th century.
They are now listed as endangered in Canada and scientists believe only a few hundred may remain alive, mainly in the western north Pacific.
Fisheries and Oceans Canada says biologist James Pilkington spotted one of the whales west of Haida Gwaii on June 9 while aboard the Canadian Coast Guard Ship Arrow Post.
Pilkington and his fellow biologists John Ford and Graeme Eliis then observed the animal for a total of 17 hours over the next few days as it foraged for zooplankton on the ocean's surface.
The federal agency says sightings of the whale are rare, and the animal has been recorded in Canadian waters only six times during the past century.
"This is a very exciting discovery. Our research group has conducted over 50,000 kilometres of whale surveys off the B.C. coast over the past 10 years and have sighted thousands of whales, but this is the first North Pacific right whale," Ford said in a statement.
"It was wonderful to see it and to confirm that the species still exists in Canadian waters."
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