Blue whales picking up where they left off?

New movement patterns may be a sign of good news for blue whales.

Blue whales have begun moving around the ocean in ways that strongly resemble their historical patterns before the advent of the whaling trade. A century ago, about 300,000 blue whales existed. But in the early 1900s, humans hunted and killed 99.9 percent of them. The population decimation made them disappear from northern waters.

A new paper published online in the journal Marine Mammal Science has shown, however, that 15 individual whales have been spotted both in the waters of southern California and the Pacific Northwest since 1997 — some even as far north as the Gulf of Alaska.

But scientists can’t yet be sure if this is in fact a return to historical migration patterns. From the New York Times Dot Earth blog by Andy Revkin:

“It’s not yet possible to determine whether the whales are resuming long-abandoned migratory feeding journeys or shifting their patterns to match cyclical shifts in the Pacific Ocean that affect  krill, their dietary mainstay, Jay Barlow, a federal whale biologist and author of the paper, said in a phone interview.”

Calambokidis, J., Barlow, J., Ford, J., Chandler, T., & Douglas, A. (2009). Insights into the population structure of blue whales in the Eastern North Pacific from recent sightings and photographic identification Marine Mammal Science DOI: 10.1111/j.1748-7692.2009.00298.x