1. Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada.
2. Faculty of Environmental Earth Science, Hokkaido University, N10W5 Sapporo, Hokkaido 060-0810, Japan.
3. International Polar Bear Conservation Centre, Assiniboine Park Zoo, 2595 Roblin Blvd., Winnipeg, MB R3R 0B8, Canada.
4. Department of Zoology, Biodiversity Research Centre and Beaty Biodiversity Museum, The University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada.