The headline-grabbing all-white adult killer whale spotted off Russia this month may well be one of a kind. But the sighting may not be the first time he's been caught on camera.

Scientists were studying acoustic and social interactions among whales and dolphins off the North Pacific's Commander Islands (map) when the team noticed a six-foot-tall (nearly two-meter-tall) white dorsal fin jutting above the waves—hence the whale's new name: Iceberg.

"The reaction from the team for the encounter, which happened on an ordinary day for spotting and photographing the whales, was one of surprise and elation," researcher Erich Hoyt said via email. Though he wasn't aboard the boat, Hoyt co-directs the Far East Russia Orca Project (FEROP), which had organized the expedition.

Though Iceberg's moniker is new, he may be the same killer whale scientists spotted in 2000 and 2008 in Alaska's Aleutian Islands (map), Holly Fearnbach, a research biologist at the University of Aberdeen in the U.K., said by email.

For one thing, Iceberg and the previously seen whales look very similar, Fearnbach said.

Furthermore, each of the three white whale sightings were among about a dozen family members, all bearing the typical black-and-white pattern, Fearnbach said.

And it wouldn't be odd for Iceberg to have made the Russia-to-Alaska crossing. Fish-eating North Pacific killer whales have been observed migrating more than 1,240 miles (2,000 kilometers). Their mammal-eating cousins cover smaller ranges.

The whale seen in 2000 and 2008 was darker and more mottled than Iceberg, FEROP's Hoyt noted, though the coloring can change seasonally due to algae on the skin, "which would tend to make a white animal look darker."

Overall, Aberdeen's Fearnbach said, "it is highly possible they are the same whales—but we cannot be certain until a match is confirmed" by closely analyzing photographs of the three sightings.

White Whale a Mystery

The 22-foot-long (7-meter-long) Iceberg is probably not a true albino, since he has color on his saddle—the area behind his dorsal fin—FEROP's Hoyt said.

"Iceberg may or may not be an albino. We really don't know," said Hoyt, also a senior research fellow at the Whale and Dolphin Conservation Society.

One way to find out would be to see if Iceberg's eyes are pink and unpigmented—a sure sign of albinism, Hoyt said. (See pictures of albino animals.)

Scientists have observed other killer whales with a condition called Chediak-Higashi syndrome, a rare disease of the immune and nervous system that affects coloration, Fearnbach said.

But most animals affected with Chediak-Higashi don't survive to adulthood, meaning it's unlikely Iceberg—a mature male of at least 16 years—has the disease. The male seen in 2000 and 2008, if different from Iceberg, also didn't have the disease.

"I do not know a lot about other genetic conditions that may cause such light pigmentation, but hopefully he will be seen again and we can collect a genetic sample," Fearnbach said.

Iceberg Healthy, Handsome

Whatever his condition, "we can see that he is a healthy-looking male, a handsome, robust member of his fish-eating pod, so we can presume that his coloration doesn't affect him in a negative way," FEROP's Hoyt said. (Some killer whale pods eat mammals, but Iceberg's group appears to stick solely to fish.)

In general, "finding a beautiful animal like Iceberg shows us that there are still great surprises to be found in the least visited parts of the ocean," Hoyt added.