Blue Whales Returning to Alaska

May 18, 2009 -- Blue whales are returning to Alaska in search of food and could be re-establishing an old migration route several decades after they were nearly wiped out by commercial whalers, scientists say.

The endangered whales, possibly the largest animals ever to live on Earth, have yet to recover from the worldwide slaughter that eliminated 99 percent of their number, according to the American Cetacean Society. The hunting peaked in 1931 with more than 29,000 animals killed in one season.

The animals used to cruise from Mexico and Southern California to Alaska, but they had mostly vanished from Alaskan waters.

But several sightings of California whales in recent years off the coasts of Alaska and British Columbia suggest that the massive animals are expanding north again in search of tiny shrimp-like krill to eat, scientists contend in a recent article published in the journal Marine Mammal Science.

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Blue whales can grow up to 100 feet long and typically eat 4 tons of krill a day during the summer.

Researchers got an inkling of the trend in 2004 during a humpback whale survey in the Gulf of Alaska, said Jay Barlow, a scientist with the National Oceanic and Atmospheric Administration.

Three blue whales were spotted in the Gulf of Alaska.

"No one had seen blue whales in these waters since the end of whaling," Barlow said.

A total of six whales were spotted in Alaska waters in 2004. The other three were in the Aleutian Islands in far western Alaska, but those belonged to the western Pacific group nearer to Russia.

Researchers compared photographs of the six whales with those in a photo identification catalog dating back to the mid-1980s. Positive matches were made by looking at the distinctive pigmentation of the skin on the whale's back and the shape of its dorsal fin.

One of the Gulf of Alaska whales matched a California whale. That whale had been seen five times in 1995 and 1998 near the Santa Barbara Channel off southern California.

After the 2004 sightings, John Calambokidis, a research biologist at Cascadia Research Collective in Olympia, Wash., who works with NOAA and the Canadian Department of Fisheries and Oceans, said one or two blue whales were spotted each year off British Columbia in 2005 and 2006.

In 2007, researchers spotted five in one day, including a mother and calf, near the Queen Charlotte Islands off British Columbia. Three more were spotted the next day.

Calambokidis, who compiled the blue whale photo identification catalog, said before that there had been only a couple of blue whale sightings in that area in the past 50 years.