Spotting killer whales off Vancouver Island is something British Columbians are often treated to, but what a group of whale watchers saw this week is truly rare.

The Nanaimo-based company Vancouver Island Whale Watch shared photos of the incredible site on its Facebook page this week.

“A WHITE orca, spotted five minutes from Nanaimo!!” said a company representative in the post. “Wild day out on the water today finding an incredibly unique and unusually coloured calf.”

The extremely rare pale-grey calf was spotted Tuesday in Dodds Narrows.

Captain Michael Campbell tells CTV News the baby transient orca was first seen in an area too close to approach with the boat.

He and the vessel with 10 passengers waited for the pod to move out of the tight location and safely followed it into open water.

At a safe distance the veteran captain said he was treated to nature at its most unique. “Just unbelievable,” said Campbell. “I’ve been driving boats for five years and I’ve never seen it.”

According to research done by the company's resident marine biologist, the calf has a genetic condition which causes its pigment to fade into an almost cloud-like grey.

Already the whale watching operation has shared their photographic catalog of the rare killer whale with federal scientists. The company says experts with Fisheries and Oceans Canada told them they aren’t even sure why this occurs in nature.

Experts at the Vancouver Aquarium are also intrigued by the photos. “This one is clearly unusual,” Lance Barrett-Lennard with Ocean Wise told CTV News.

The director of the Marine Mammal Research project at the aquarium says he’s seen lightly coloured orcas before in B.C. waters, but notes this calf is extremely faded in colour.

He says often killer whale calves undergo pigment changes in their first years of life, but normally the shifts occur on their eye patches and in the colouration of their white stripes.

While Barrett-Lennard isn’t exactly sure what genetic condition caused this whale to turn the faded colour, he is sure it isn’t albinism. “The fact that it has a clear eye patch indicates that it’s not an albino.”

The Vancouver Aquarium expert says while the pigment condition could be harmless for the whale, he has seen calves with a similar pale complexion deal with more serious health issues associated with their genetic makeup.

The transient orca calf, known as T46B1B, has apparently been spotted before off Vancouver Island, but is not known to have been so closely photographed.

Unlike their endangered salmon-eating cousins the southern resident killer whales, transient orcas eat larger mammals such as seals and sea lions.

Transient orca populations are considered stable in B.C. waters.

Whale watching vessels must stay 200 metres away from transient killer whales, and 400 metres back from southern residents.