The success story of the Pacific gray whales' full recovery from near-extinction is wrong, according to a new genetic analysis that pegs the current population at only one-third to one-fifth of historical levels.
By examining subtle variations in DNA taken from 42 modern whales, scientists have concluded that between 78,500 and 117,700 gray whales lived before the heyday of commercial whaling in the 19th and 20th centuries.
That finding, published today in the Proceedings of the National Academy of Sciences, suggests that the about 22,000 gray whales now swimming along the California coast remain a depleted population.
"It's startling for us to consider the California gray whale, which we considered recovered for more than a decade, has not recovered after all," said Scott Baker, a researcher at Oregon State University's Marine Mammal Institute in Newport, Ore., who was not involved in the study.
The results counter what had been a predominant scientific view that the iconic creatures of the West Coast were so bountiful that they were overgrazing their traditional feeding grounds.
Instead, the findings provide further evidence that this year's abnormally high number of skinny whales is a sign of deterioration of the vast ocean ecosystem that stretches from Baja California to the Bering Sea.
"If the oceans a few hundred years ago could support 100,000 gray whales, why can't the oceans sustain 20,000 whales today?" said Stephen Palumbi, a Stanford University marine sciences professor and senior author of the study.
Palumbi caused a scientific commotion four years ago when he and a Harvard University colleague estimated that humpback, fin and minke whales in the North Atlantic were once two to 10 times more abundant than their current population levels.
Besides challenging conventional estimates, their study presented a political problem for the International Whaling Commission, which oversees a global ban on commercial hunting.
The commission has long promised to allow whaling nations such as Japan and Norway to resume operations once certain species have recovered to 54% of historic levels.
In the case of humpback whales, Palumbi estimated that it would take 70 to 100 years before the population reached such a threshold.
Gray whales are now hunted by native peoples, who are allowed to kill up to 140 animals each year. Nearly all are harpooned by traditional Russian hunters off the coast of Siberia, although Washington state's Makah tribe has been trying to reassert its right to hunt gray whales.
