1. Department of Animal Biology (Vertebrates) Faculty of Biology, University of Barcelona Diagonal 645, 08028 Barcelona, Spain
2. Sea Mammal Research Unit, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 OET, UK
3. Greenpeace International, Mediterranean Sea Project, Ses Rafaletes 13 1°, 07015 Palma de Mallorca, Spain