Pacific walrus (Odobenus rosmarus divergens) resource selection in the Northern Bering Sea

PLoS One. 2014 Apr 9;9(4):e93035. doi: 10.1371/journal.pone.0093035. eCollection 2014.

Abstract

The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya) in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%). Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Biomass
  • Ecosystem*
  • Geography
  • Ice Cover
  • Models, Biological
  • Oceans and Seas*
  • Pacific Ocean
  • Probability
  • Walruses / physiology*

Grants and funding

Financial support was provided to PIs Grebmeier and Cooper through the U.S. National Science Foundation (ARC-082290) and the North Pacific Research Board (BSIERP Project B67). Walrus tagging data in 2006 was obtained from a separate project with financial support from U.S. Fish & Wildlife Service, U.S. Geological Survey, and North Pacific Research Board (NPRB #632). Tagging data in 2008 and 2009 was obtained specifically for this project with ship and aerial support from the U.S. National Science Foundation and financial support from the U.S. Geological Survey, Ecosystems Mission Area, Wildlife Program, and North Pacific Research Board (NPRB #B67). This work was assigned the following project numbers: BEST-BSIERP Bering Sea Project publication number 136 and NPRB publication number 480. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.