The whale was spotted about two miles (three kilometers) off Kanaga Volcano on February 23.
The whale was spotted last month whereas scientists aboard the Oscar Dyson—a National Oceanic and Atmospheric Administration (NOAA) research ship—were conducting an auditory survey of Pollock, a whitefish, near Stellar sea lion drag out sites.
Though the whale's saddle part was white, further parts of its body had a slight yellowish or brownish shade, signifying it was not a true albino, Durban said.
"This is the first time we came athwart a white killer whale," agreed John Durban, a research biologist at NOAA's Alaska Fisheries Science Center in Seattle.
Fearnbach said the white whale stood out.
"When you first looked at it, it was exceptionally white," she said Thursday.
It appeared to be a healthy, adult male about 25 to 30 feet (7 to 9 meters) long and weighing as much as 10,000 pounds (4,500 kilograms).
And that's latest on rare White Killer Whale