Scientists have glimpsed a pure white adult orca, or killer whale, while on a research expedition off the far eastern coast of Russia.
The sighting in waters off the Kamchatka peninsula is believed to be the first time such a whale has been seen in the wild.
Researchers said the marine mammal, which they nicknamed Iceberg, was swimming with its mother and siblings and appeared to be fully accepted by its 12-strong family.
White whales are not unheard of, but only young white orcas are thought to have been recorded by marine conservationists before.
The whale was seen by scientists on a research cruise co-led by Erich Hoyt of the Far East Russia orca project.
"We've seen three white orcas in the past few years, but this is the very first time we've seen a mature animal that is all white," Mr Hoyt, a senior research fellow at the Whale and Dolphin Conservation Society, told The Guardian.
The team is returning to the same waters next month to try to track it down again.
The scientists hope to confirm whether or not Iceberg is an albino by photographing its eyes.
"If we can get a full close-up of the eyes and they are pink, it would confirm Iceberg is an albino, but we don't know much about albinism in orcas," Mr Hoyt said.
Fully albino orcas can have weak immune systems and die young, but partial albinos can live into adulthood.
Iceberg appears to be white all over and, judging by its two-metre dorsal fin, is at least 16 years old, Mr Hoyt said.
"We've photographically identified 1500 orcas in the region in the past 12 years there," he said. "If we see any of his pod and he's not there, we'll know he's gone."
During the expedition from May to September, researchers will lower hydrophones into the sea to record the sounds the whales make.
There are believed to be three to four "clans" of whales in the waters the team surveyed, each with its own distinctive dialect.
Guardian News & Media