Rare white whale sighted off Seattle and Tacoma: a wayward beluga

A white whale has been spotted swimming along the Seattle and Tacoma waterfronts.

Call it Moby Duwamish.

Or Moby Defiance.

This pale whale is much smaller than the nemesis of Captain Ahab in Herman Melville's Moby Dick.

It was spotted in Tacoma's Commencement Bay on Sunday, swimming quietly between a sailboat and a barge full of scrap metal. Boater Jason Rogers captured video of the white whale, close enough to hear it exhale, and reported it to the nonprofit Orca Network.

The whale was seen swimming around Seattle’s Elliott Bay on Monday.

Marine mammal experts soon confirmed that it was a beluga whale, 1,200 miles or more from the nearest known populations of its species in the Gulf of Alaska.

WATCH: Video of a beluga whale swimming in Tacoma's Commencement Bay on Oct. 3

Belugas are normally found in the Arctic Ocean and nearby sub-Arctic waters.

The National Marine Fisheries Service says belugas may number in the hundreds of thousands worldwide, though a population living amid the shipping lanes and oil rigs of Cook Inlet, near Anchorage, Alaska, is considered endangered, with about 280 individuals. An isolated group of about 12 belugas lives in Alaska's Yakutat Bay, about 400 miles east of Cook Inlet.

Beyond being white from melon-shaped head to tail, belugas are unusual among whales in lacking a dorsal fin. Their streamlined backs let them swim just beneath the sea ice that forms each winter in their normal haunts.

They live up to 90 years, reach up to 16 feet in length, and can weigh more than 3,000 pounds.

Belugas make so many different sounds, including chirps, clicks, moos, squeals, and whistles, that they are sometimes called "canaries of the sea."

It's exceedingly rare, though not unheard of, for a beluga to swim this far south.

“I can't explain why it's here and haven't heard anyone else come up with a plausible theory,” Howard Garrett with Orca Network said in an email. “Sometimes whales and dolphins just seem to go for a walkabout.”

National Geographic reports that a beluga was seen "off the coast of Washington State" in 1940.

A whale watch captain documented a beluga near San Diego last July. By October, it had washed up dead in a lagoon in Baja California, 400 miles farther south.

“Belugas are social whales who live and travel in pods, so a lone beluga will have a hard time of it, and we hope s/he finds her/his way home safely,” Susan Berta of Orca Network said in an email.

Researchers are asking the public to stay at least 100 yards from the whale, as required by federal law, and to report any sightings immediately to Orca Network at 1-360-331-3543 or the National Marine Fisheries Service’s Marine Mammal Stranding Network at 1-866-767-6114.

Correction, 9:10 a.m., 10/7/21: An earlier version misstated the location of the closest known beluga population to Washington state.

WATCH: Video of a beluga whale swimming off San Diego in July 2020