1. Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom
2. Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom and Cetacean Research Laboratory, Vancouver Aquarium, P.O. Box 3232, Vancouver, British Columbia V6B 3X8, Canada
3. Zoovisions, Cumberlandsgade 5, 3. tv., 2300 København S., Denmark
4. Húsavik Research Centre, University of Iceland, Hafnarstétt 3, 640 Húsavik, Iceland