A study of the narrow passage of the Bering Strait uses underwater microphones to track the whales by their sounds. Three years of recordings reveal more detections of both Arctic and sub-Arctic whales traveling through the narrow choke point.
The Bering Strait is a shallow, 58-mile-wide channel between Russia and Alaska that connects the Pacific and Arctic oceans. The Chukchi Sea is to the north, and the Bering Sea is to the south.
The recordings show Arctic beluga and bowhead whales migrating seasonally through the region from the Arctic south to spend winter in the Bering Sea. They also detect large numbers of sub-Arctic humpback, fin and killer whales traveling north through the Bering Strait to feed in the biologically rich Chukchi Sea.
Kate Stafford is an oceanographer with the University of Washington’s Applied Physics Laboratory. She said:
It’s not particularly surprising to those of us who work up in the Arctic,” Stafford said. “The Arctic seas are changing. We are seeing and hearing more species, farther north, more often. And that’s a trend that is going to continue.
Stafford placed microphones below the water’s surface and recorded in summer and early winter from 2009 to 2012 as part of a U.S.-Russian scientific collaboration. Melodious humpback whale songs showed up regularly on recordings into late fall. Fin and killer whales, which are southern species that seldom travel into Arctic waters, were heard into early November. Stafford said:
These animals are expanding their range. They’re taking advantage of regions in seasons that they may not have previously.
The recordings also picked up ships using the ice-free summers to travel through two international shipping lanes. This poses an increased risk of collisions between whales and ships, and of noise pollution.
The Arctic areas are changing, said Stafford. She added:
They are becoming more friendly to sub-Arctic species, and we don’t know how that will impact Arctic whales. Will they be competitors for food? Will they be competitors for habitat? Will they be competitors for acoustic space, for instance these humpbacks yapping all the time in the same frequency band that bowheads use to communicate? We just don’t know.