Observing Arctic Marine Mammals

Walrus spotted during the 2010 RUSALCA expedition

Walrus spotted during the 2010 Russian-U.S. Arctic Census expedition. Click on image for credit and larger view.


Kate Stafford
Principal Oceanographer
Applied Physics Laboratory, University of Washington

Polar bears crossing the Arctic ice.

Polar bears crossing the Arctic ice. Click image for larger view and image credit.


The Bering Strait is the only gateway from the Pacific to the Arctic. As such, it is an important migratory corridor for marine mammals that spend the winter in the Bering Sea but much of the rest of the year in the Arctic. These species include Arctic-adapted animals such as bowhead and beluga whales, ice seals, polar bears, and walrus.  

With recent climate-change caused reductions in summer and fall sea ice extent, however, sub-Arctic species like gray, fin, humpback, and killer whales are being sighted with increasing frequency north of the Bering Strait in the Chukchi and Beaufort Seas.  One way to monitor these changes is to document the presence of different species in an area using visual surveys.

On Leg 1 of this year's Russian-American Long-term Census of the Arctic (RUSALCA) cruise, hydrophones (underwater microphones) were put in place to listen for marine mammals. Because marine mammals tend to be rather vocal in communicating with each other, and different species produce distinctive sounds, such as songs, moans, clicks, sighs, and buzzes, recording underwater sounds can help researchers learn about the behaviors of these animals.

The tail of a bowhead whale breaks the surface.

The tail of a bowhead whale breaks the surface. Click image for larger view and image credit.


A pod of orca, or killer, whales observed during the 2012 RUSALCA expedition.

A pod of orca, or killer, whales observed during the 2012 RUSALCA expedition. Click image for larger view and image credit.


Listening to these underwater sounds and learning about the behaviors can also help researchers find marine mammals. During the first leg of the cruise, in addition to deploying hydrophones, observers were on the bridge of the ship during all daylight hours to look for marine mammals. Despite good weather, there were few sightings in the eastern Chukchi Sea. 

audio icon Sounds from the Sea

These sounds were collected using instruments deployed as part of the RUSALCA project and recovered during the first leg of the 2012 cruise. Sounds courtesy of Kate Stafford; require QuickTime to listen.

Sounds courtesy of Kate Stafford; require QuickTime.

During leg 2, while the hydrophones are busy collecting data under the sea, marine mammal observations will once again be made as the ship surveys in both U.S. and Russian waters. Observations will be made from the bridge during all daylight hours using high-powered binoculars and tracking software to document all marine mammals seen.  

These observations will give us a rare glimpse of sea life across the date line. During the 2010 RUSALCA expedition, more than half of all sightings were made in Russian waters and included sightings of bowhead, humpback, gray, and killer whales, as well as polar bears and walrus.

 

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