The whaling ships of the past are gone, no longer a factor in the lives of gray whales. As a result, the population has rebounded, with perhaps as many of the whales today as existed in the days before the mass killing began. But large die-offs of whales in recent decades--followed by rebounds in the numbers--sent scientists in search of causes.
New research led by an Oregon State University scientist points to a place: the Arctic. Changes in ice cover and the small animals the whales eat appear to cause great fluctuations in gray whale survival. Joshua Stewart at the Marine Mammal Institute of OSU, the lead author, lays out the findings.