1. Centre for Ecological and Evolutionary Synthesis (CEES); Department of Biosciences; University of Oslo; PO Box 1066, Blindern 0316 Oslo Norway
2. Alaska Fisheries Science Center; National Oceanic and Atmospheric Administration; 7600 Sand Point Way NE Seattle WA 98115 USA
3. Department of Mathematics; University of Oslo; PO Box 1053, Blindern 0316 Oslo Norway
4. Institute of Marine Research; Flødevigen 4817 His Norway
5. Centre for Coastal Research; University of Agder; N-4604 Kristiansand Norway