Habitat selection by two beluga whale populations in the Chukchi and Beaufort seas

PLoS One. 2017 Feb 24;12(2):e0172755. doi: 10.1371/journal.pone.0172755. eCollection 2017.

Abstract

There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice conditions. We established habitat selection models that incorporated daily sea ice measures (sea ice concentration, proximity to ice edge and dense ice) and bathymetric features (slope, depth, proximity to the continental slope, Barrow Canyon, and shore) to establish quantitative estimates of habitat use for the Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') populations. We applied 'used v. available' resource selection functions to locations of 65 whales tagged from 1993-2012, revealing large variations in seasonal habitat selection that were distinct between sex and population groups. Chukchi whales of both sexes were predicted to use areas in close proximity to Barrow Canyon (typically <200 km) as well as the continental slope in summer, although deeper water and denser ice were stronger predictors for males than females. Habitat selection differed more between sexes for Beaufort belugas. Beaufort males selected higher ice concentrations (≥40%) than females (0-40%) in July-August. Proximity to shore (<200 km) strongly predicted summer habitat of Beaufort females, while distance to the ice edge was important for male habitat selection, especially during westward migration in September. Overall, our results indicate that sea ice variables were rarely the primary drivers of beluga summer-fall habitat selection. While diminished sea ice may indirectly affect belugas through changes in the ecosystem, associations with bathymetric features that affect prey availability seemed key to habitat selection during summer and fall. These results provide a benchmark by which to assess future changes in beluga habitat use of the Pacific Arctic.

MeSH terms

  • Animals
  • Arctic Regions
  • Beluga Whale / physiology*
  • Ecosystem*
  • Environmental Monitoring*
  • Male
  • Oceans and Seas
  • Population Control*
  • Seasons

Grants and funding

Tagging of Chukchi belugas was funded by the Alaska Beluga Whale Committee, North Slope Borough of Alaska, National Marine Fisheries Service (NMFS), Alaska Department of Fish and Game, National Fish and Wildlife Foundation, Minerals Management Service, and Village of Point Lay. Tagging of Beaufort belugas was funded by the Fisheries and Oceans Canada, Fisheries Joint Management Committee, Environmental Studies Revolving Fund, Minerals Management Service, and NMFS. Analyses by D.D.W.H, K.L.L., and H.L.S. were partially funded by NASA Climate Indicators Program Grants (NNX13AN28G and NNX16AG33G) and fellowships to D.D.W. Hauser from the University of Washington’s (UW) Integrative Graduate Education and Research Traineeship Program on Ocean Change (National Science Foundation DGE-1068839) and UW School of Aquatic & Fishery Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.