Four species of ice-associated seals inhabit the Bering Sea:  ribbon (Histriophoca fasciata), ringed (Pusa hispida), bearded (Erignathus barbatus), and spotted seals (Phoca largha). These seals are key components of arctic marine ecosystems and they are important resources for the Alaska Natives of northern and western Alaska.  The seals that live near shore have been studied for many years but we know very little about the seals that occupy the marginal ice zone of the Bering Sea.

Ice extent in the Bering Sea has decreased in recent years and there are many questions about how seals will respond to changing sea ice conditions. For example: Will the seals move into new areas (possibly moving north to stay with the sea ice)?  Will their usual prey move into different areas or be reduced in numbers, perhaps making it harder for seals to find food?  Will the seals have to travel longer distances to reach their foraging grounds from their resting areas on the ice?

Ribbon seal.

In order to answer some of these questions, we are going to have the seals collect data for us.  Researchers from NOAA’s National Marine Mammal Laboratory will use small boats to reach ice floes occupied by seals. The seals will be captured using nets, and an instrument will be attached to the seals’ back using quick-setting glue.  The instruments will fall off with the animal’s next molt (when they lose their hair) which could be between 1 and 11 months.  These instruments are called oceanographic-sampling, satellite-linked time-depth recorders (OSSLTDRs), and they collect information about the temperature and salinity of the surrounding water and the movements of the seals.  These data will be transmitted back to us by satellite and will provide information on:

• where the seals live throughout the seasons (even when the ice is gone),
• what the oceanographic conditions are around the seals,
• how the seals forage (find food) and,
• how much time the seals spend in and out of the water. 

Spotted seal on ice floe.

We will compare data collected by the different projects of this expedition (fish, zooplankton, and physical oceanography) with the data collected by the seals (and their attached OSSLTDRs) to better understand the habitat selection of ice seals in the marginal ice zone ecosystem. This will improve our understanding of these seals and help us to predict how changing sea-ice conditions may affect them.

Images on this page and their links are credited to Michael Cameron, NOAA/Nation Marine Mammal Laboratory. He also took the seal photo on the picture bar at the top.