Walrus distributional and foraging response to changing ice and benthic conditions in the Chukchi Sea

Arctic species such as the Pacific walrus (Odobenus rosmarus divergens) are facing a rapidly changing
environment. Walruses are benthic foragers and may shift their spatial patterns of foraging in response to
changes in prey distribution. We used data from satellite radio-tags attached to walruses in 2009-2010 to
map walrus foraging locations with concurrent sampling of benthic infauna to examine relationships
between distributions of dominant walrus prey and spatial patterns of walrus foraging. Walrus foraging
was concentrated offshore in the NE Chukchi Sea, and coastal areas of northwestern Alaska when sea ice
was sparse. Walrus foraging areas in August-September were coincident with the biomass of two
dominant bivalve taxa (Tellinidae and Nuculidae) and sipunculid worms. Walrusforaging costs
associated with increased travel time to higher biomass food patches from land may be significantly
higher than the costs from sea ice haul-outs and result in reduced energy storesin walruses. Identifying
what resources are selected by walruses and how those resources are distributed in space and time will
improve our ability to forecast how walruses might respond to a changing climate.