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Understanding and Forecasting the Response of Pacific Walrus Populations to a Rapidly Diminishing Sea Ice Environment

Long-term studies of walruses to inform management decisions and understand impacts of declining sea ice on a sea-ice dependent species.


Sea ice decline and its impact on Pacific walruses are of great concern. Female walruses use sea ice to rest and nurse their young in the Bering and Chukchi Seas. They rely on the close proximity of sea ice to the continental shelf where their benthic prey is abundant and accessible to shallow foraging. Sea ice is less extensive and thinner in the Bering Sea, retreating more quickly in late spring, and is less extensive over the shelf in the Chukchi Sea in summer and early fall, than in previous years. This may alter walrus foraging distribution and behavior in the Bering Sea and has resulted in more rapid northward migration of walruses and decreased sea ice habitat within their summer foraging range. Walruses have become less accessible to Alaska Native subsistence hunting, and anecdotal information suggests that female walruses and calves are responding to decreased sea ice in summer by increasing their use of land haul-outs in Russia, possibly leading to more costly foraging energetics and decreased calf survival. In addition, oil and gas exploration in northern lease sale planning areas has prompted requests for more information on walrus migration routes and foraging areas in the Chukchi Sea, which are currently not well documented. This information is important to oil and gas industry to help mitigate potential impacts to walruses from offshore exploration and development activities; U.S. Bureau of Ocean Energy Management and Fish and Wildlife Service for oil and gas lease sales, MMPA authorizations, NEPA analyses, and as documentation in the approval of exploration and development plans; and to coastal Native communities that rely on sufficient nearshore access to walruses for subsistence. USGS is responding to these information needs by initiating new radio-tagging studies in the Bering and Chukchi Seas to better understand changes in walrus distributions and foraging behaviors relative to sea ice conditions. Other studies will be initiated to gain insights into likely population responses to altered walrus distributions and foraging strategies, and an improved understanding of ice dynamics in the Bering and Chukchi Seas relevant to the lives of walruses.

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Page Last Modified: December 06 2016 16:16:21.