1. Sea Mammal Research Unit, Scottish Oceans Institute, University of Saint Andrews, Saint Andrews, Fife KY16 8LB, UK
2. International Coastal Research Centre, Atmosphere and Ocean Research Institute, The University of Tokyo, 2-106-1 Akahama, Otsuchi, Iwate 028-1102, Japan
3. National Institute of Polar Research, 10-3, Midoricho, Tachikawa, Tokyo 190-8518, Japan
4. Department of Biology, Sonoma State University, Rohnert Park, CA 94928, USA
5. Long Marine Laboratory, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
6. Norwegian Polar Institute, Polar Environmental Centre, 9296 Tromsø, Norway
7. Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan