The Bering Strait Poses Increased Risk of Collision between Whales and Ships [VIDEO]

A large population of whales and ships is increasingly using the ice-free Bering Strait, the channel that connects the Pacific and Arctic Oceans, raising the risk of collision with ships.

In the recent past, the Arctic sea ice has melted unusually early in the spring due to which a large number of whale population is travelling north towards the Bering Sea to feed in the biologically rich Chukchi Sea. In a three-year study researchers used underwater microphones to track these whales by their sounds.

This study was done was with Russian scientific collaboration. For the study, researchers placed microphones below the water surface and tracked the sounds of the whale in the summer and early winter from 2009-2012. During the late fall, songs of humpback whale frequently showed up. On the other hand the fin and killer whales, which rarely travel into the Arctic waters, were heard early
November.

During the three years of recording, the researchers detected a growing number of both Arctic and sub-Arctic whales using the narrow choke point to travel north into the new ice-free Arctic waters. This study was led by Kate Stafford, an oceanographer with the University of Washington's Applied Physics Laboratory.

"It's not particularly surprising to those of us who work up in the Arctic," Stafford said in a statement. "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."

Analyses of the recordings reveal that the Arctic beluga and bowhead whales seasonally migrate through the channel from the Arctic South to the Bering Sea during the winters. Apart from this, a growing number of sub-Arctic humpback whales, fin whales and killer whales head to the north through the Bering Strait to forage on the crustacean zooplankton.

Along with the whale sounds the microphones even recorded the sounds of ships. This poses a high risk of collision between whales and ships as well as noise pollution.

"These animals are expanding their range," Stafford said. "They're taking advantage of regions in seasons that they may not have previously. Marine mammals rely primarily on sound to navigate, to find food and to find mates. Sound is their modality. If we increase the ambient sound level, it has the potential to reduce the communication range of cetaceans and all marine mammals."

The Bering Strait is a land bridge and is 58 miles wide and 160 feet deep with nearly a third of its span in U.S. waters and the rest in Russia.

A study earlier by Stafford offered visual sightings of the killer whales towards the north of the strait in the southern Chukchi Sea.

"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."

With this study the researchers suggest that by reducing the ship speed in the Bering Strait, the motor noise pollution reduces and also lowers the risk of collision. It was seen that the bowhead whales headed towards the U.S. in the spring and the Russia side during the fall. Knowing this the interaction between ships and whales can be reduced if the ships follow the opposite route.