February 28, 2014
Ships On A Collision Course With Whales In The Bering Strait
Brett Smith for redOrbit.com - Your Universe Online
Diminishing sea ice in Arctic waters has opened up new lanes of aquatic traffic and new research from the University of Washington has found that when it comes to the Bering Strait – whales and commercial ships are on a collision course.
The new research, presented at the Ocean Sciences meeting in Honolulu on Wednesday, is based on three years of underwater recordings in the Bering Strait. UW research Kate Stafford found Arctic beluga and bowhead whales migrating south through the area spend winter in the Bering Sea. Underwater microphones also identified large numbers of sub-Arctic humpback, fin and killer whales passing north through the Bering Strait to hunt in the Chukchi Sea.
“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.”
The microphones were set to record annually in summer and early winter from 2009 to 2012. Humpback whale songs regularly popped up well into late autumn. Fin and killer whales, which usually live south of Arctic waters, were heard into early November.
“These animals are expanding their range,” Stafford explained. “They’re taking advantage of regions in seasons that they may not have previously.”
The recording devices also detected ships passing through international shipping lanes during the summer recording sessions – raising the prospect of noise pollution as well as accidents between whales and ships.
“Marine mammals rely primarily on sound to navigate, to find food and to find mates. Sound is their modality,” Stafford said. “If we increase the ambient sound level, it has the potential to reduce the communication range of cetaceans and all marine mammals.”
Once a land bridge ancient peoples used to cross from Asia into the Americas, the Bering Strait is just 58 miles wide and 160 feet deep. This relatively small stretch of sea is shared by several whale species and commercial ships. It is also being considered for oil and gas exploration.
“The Arctic areas are changing,” Stafford said. “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.”
Stafford and others have suggested that ships slow down upon entering the strait – reducing motor noise and the risk of ship-whale accidents. Based on previous research that tracked the paths of bowhead whales, another suggestion to reduce interactions between ships and whales is to have ships follow the American side of the strait in the fall and the Russian coast in the spring.
Scientists are currently looking into whether increased whale travel through the region is the result of rising whale populations, expanded ranges, or both.
“The question is, are these whale populations recovering and so they’re reoccupying former habitat, or are they actually invading the Arctic because they can, because there is less seasonal sea ice?” Stafford asked.