Written by: Ryan Wilson

United States Fish and Wildlife Service

Marine Mammals Management

Anchorage, Alaska

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The Chukchi Sea polar bear subpopulation is one of 19 recognized subpopulations and is one of two subpopulations that reside in the United States.  To better understand how sea ice loss has affected polar bears in the Chukchi Sea, the U.S. Fish and Wildlife Service and the U.S. Geological Survey have been researching their ecology and space use patterns since 2008. 

 

Prior to this work, little research had been conducted on the subpopulation since in the 1980s and early 1990s.  Thus, little was known about how bears in this area had responded to significant sea ice loss during this period.  To learn more about the subpopulation’s ecology, we annually capture 50-70 bears in the spring, collaring 15-20 adult females with Argos satellite-collars, and tagging 5-10 sub-adult bears and adult males with Argos satellite ear tags to track their annual movements.     

 

One of our primary uses of these location data is to better understand where important polar bear habitat is currently located to inform management decisions, such as how offshore oil and gas drilling might interact with polar bears.  That was the focus of a recent study we published in the journal Ecosphere (http://onlinelibrary.wiley.com/doi/10.1890/ES14-00193.1/full), looking at the overlap of high-value polar bear habitat with areas open to oil and gas leasing offshore. This analysis also determined what environmental factors polar bears prefer throughout the year; shallow-productive waters over the continental shelf, and areas with higher sea ice concentration that have a higher potential for seals being present and vulnerable to predation.

 

Another important area of research has been comparing space use patterns from data collected prior to significant sea ice loss and now.  Based on location data derived from Argos-enabled collars, we have found that polar bears in the Chukchi Sea have increased the amount of time spent on land by nearly a month in response to sea ice loss, with nearly all land use now occurring in Russia compared to earlier where some occurred on the U.S. coastline.  These findings are detailed in a study published in the journal PLoS One (http://dx.doi.org/10.1371/journal.pone.0142213). 

 

Finally, we have used the location data from Argos to understand how habitat conditions have changed for polar bears in the Chukchi Sea.  In this study we found that bears have not changed what habitat features they prefer, but that the amount of area with these features has declined significantly during summer but has not changed during the rest of the year.

 

Overall, our use of Argos satellite-derived location data has significantly increased our understanding of polar bears in this region and will continue to provide important information for years to come.

 

-Ryan Wilson