All-white killer whale spotted in Pacific Ocean

But they will not know for sure until they can glimpse mammal's eyes and discover whether they are red or not. Researchers plan to track Iceberg and his pod over the summer months.

There have been reports of white orcas before, including a sighting off the Aleutian Islands near Alaska in 2008. But the most famous white whale is the eponymous hero of Herman Melville's Moby Dick – a white sperm whale.

The scientists who came across Iceberg were working as a part of the Far East Russia Orca Project, begun in 1999 to protect killer whale populations under threat from hunting teams seeking to capture them for aquariums. They have sighted and catalogued about 1,500 whales so far.