Researchers are closely monitoring a young killer whale with an injury that may have been caused by a boat strike off the coast of Vancouver Island.

The whale was spotted with a fresh wound on its flank and dorsal fin on Saturday in Johnstone Strait.

Researchers identified her as A95, a six-year-old killer whale from the northern resident population known as Fern.

"The wound appeared extensive but superficial, consistent with an injury inflicted by a propeller, and quite fresh, likely from the same morning," the Vancouver Aquarium said in a press release.

"As they observed the whale, it was vigorous, engaged in social activity and apparently behaving normally."

Although this wound appears superficial and is likely to heal, it could have been much worse, said the aquarium's research biologist, Meghan Moore.

"The wound appeared extensive but superficial, consistent with an injury inflicted by a propeller," said the Vancouver Aquarium. (Vancouver Aquarium/NOAA)

"Although rare, incidents of boat strikes on killer whales do happen," she said.

"Twelve years ago, A95's great uncle A60 [Fife] was spotted with a series of deep, parallel cuts on and just below the right side of his dorsal fin. We believe they were caused by a boat propeller."

Fife, however, is alive and its injuries have healed.

Boaters should maintain a distance of at least 100 metres around whales and dolphins, the aquarium added.