1. School of Biological Sciences, Lighthouse Field Station, University of Aberdeen, Cromarty, Ross-shire IV11 8YJ, UK
2. Wildlife Ecology and Conservation Group and Wageningen Marine Research, Wageningen University and Research, Ankerpark 27, 1781 AG Den Helder, The Netherlands
3. Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, Texel, The Netherlands
4. Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Fife KY16 9LZ, UK
5. School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
6. Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK