Gray whales swimming
Credit: Sue Moore / NOAA Magazine
When scientists moored a couple of acoustic recorders in the Arctic Ocean northeast of Barrow in October 2003, they wanted to eavesdrop on the songs of bowhead, gray and other cetaceans as they feast on the polar ocean’s summer bounty.
And then, as darkness fell and the ocean froze, the whales would exit though the Bering Strait and the sea would go silent.
After all, the great whales can die if caught in thick ice — three gray whales trapped in ever shrinking leads near Barrow triggered an international rescue in the fall of 1988. At least one animal disappeared before a Russian ice-breaker plowed a path to open water.
But a few gray whales didn’t get the memo.
Instead of joining 10,000 other Pacific grays on their 5,000-mile fall migration to wintering grounds in Mexico, the intelligent bottom-feeding invertebrate munchers spent the winter amid Alaska’s Arctic pack.
In a stunning finding that raises questions about accelerating climate change and undermines assumptions about gray whale behavior, an autonomous acoustic device anchored 4,100 feet beneath the surface of the frozen Beaufort Sea recorded gray whale calls throughout the winter of 2003-04.
“Because this is the first-ever winter-long acoustic study, we cannot be certain that gray whales have not over-wintered in the Beaufort Sea in the past,” the authors wrote in a report published in June in the journal Arctic. “However, a combination of increasing population size and habitat alteration associated with sea ice reduction and warming in the Alaskan Arctic may be responsible for the extra-seasonal gray whale occurrence near Barrow.”