1. Professor in the Biology Department, Princeton University, Princeton, New Jersey 08540
2. Lecturer in the Biology Department, University of York, Heslington, York, Y01 5DD, England
3. Professor in the Mathematics department, University of British Columbia, Vancouver V6T IW5, Canada
4. Adviser on marine affairs to the Fisheries Department, United Nations Food and Agriculture Organization, Via delle Terme di Caracaila, 00100 Rome, Italy
5. Director of the British Antarctic Survey, Madingley Road, Cambridge, CB3 OET, England