Gray whales a fraction of historic levels, genetic res...( Gray whales in the Pacific Ocean lon...)

Gray whales in the Pacific Ocean, long thought to have fully recovered from whaling, were once three to five times as plentiful as they are now, according to a report to be published September 10 in the Proceedings of the National Academy of Sciences.

Todays population of more than 22,000 gray whales has successfully been brought back from the threat of extinction and is now the most abundant whale on the North American west coast. But the new findings from researchers at Stanford University and the University of Washington suggest that the current population is actually far below the original numberestimated by genetic methods at 96,000 animalsthat once roved the Pacific Ocean.

The report also weighs in about why large numbers of gray whales have recently been discovered suffering from starvation. Previously it was assumed that the thin and starving animals are a consequence of the gray whale population exceeding its historical ecological limits. But if the Pacific normally housed 96,000 gray whales, then starving whales may be suffering reduced food supply from changing climate conditions in their Arctic feeding grounds. This possibility parallels reports last year of major climate shifts in the Arctic ecosystems in which gray whales feed. The study also suggests that lowered numbers of gray whales no longer play their normal role in ocean ecology.

Gray whales were hunted extensively in the late 19th century. "The lagoons of Baja California were the primary killing fields for gray whales," recounted lead author S. Elizabeth Alter, a Stanford researcher. "But we don't know exactly how many there were before whaling took its toll." The new research measures the amount of genetic variation in current gray whales across ten different sections of their genome, and back calculates the long-term population size based on new measurement of the mutation rate of these gene segments.

Steve Palumbi, the Harold A. Miller Professor
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