ANCHORAGE - Federal scientists have sighted a rare mammal in Alaska waters - endangered blue whales, the largest animal known to live on Earth.
The sighting by researchers on board a National Oceanic and Atmospheric Administration vessel means the blue whale population may be getting healthier and expanding back to traditional territories.
"We are thrilled," Dr. Jay Barlow, chief scientist on board the McArthur II for a 120-day research cruise, said Friday from Kodiak. "It's been 30 years since we had a confirmed sighting up here."
Most recent population estimates show about 12,000 blue whales worldwide, with about 2,000 in U.S. waters off California in summer and fall. Others are found in the western Pacific, the North Atlantic, the Indian Ocean and the Antarctic. Blue whales in the Pacific can reach 85 feet long, and 100 feet long in the Antarctic, Barlow said.
Blue whales are believed to migrate in the North Pacific in summer to northern feeding grounds, where they eat about four tons of krill per day, putting on fat for the winter. In winter, the eastern Pacific group migrates south to calving grounds off Mexico and Costa Rica, Barlow said.
Blue whales were hunted commercially between 1860s and the 1960s, with an estimated 350,000 killed during that period, including thousands in Alaska. They have been protected since 1965.
Scientists on the McArthur II are studying humpback whales on the research cruise, which ends in November. The vessel sails in zigzag patterns from shore up to 200 miles out in traditional whaling waters.
The vessel was about 100 nautical miles southeast of Prince William Sound, where the ocean is approximately two miles deep, on July 15 when spotters saw the first blue whale in late afternoon of an overcast day.
Three spotters on the flying bridge saw a tall blow six to seven miles away, Barlow said. Blue whales blow plumes about 20 feet high, but from so far away, no spotter was willing to speculate it was a blue whale rather than a smaller fin whale - the second-largest whale - which had been seen regularly.
The ship turned toward the whales, and when the animals were within two miles, spotters using 25-power pedestal-mounted binoculars could see they were blue whales, easily identifiable by their tiny dorsal fins.
"The real giveaway is the shape and size of the dorsal fins, and the coloration," Barlow said. Fin whales are black. Blue whales look blue in the water and slate-gray out.
For whale researchers, Barlow said, the sighting was huge.
"There have been many marine mammal surveys in Alaska by ship and aircraft, and countless years of small boat research on humpback whales in Alaska, and yet, these are the first fully documented sightings of blue whales here in the past three decades," Barlow said.
Researchers were able to get close enough to obtain skin and blubber samples, which will be used for genetic testing and pollutant studies.