[1] Thunen Inst Sea Fisheries, Palmaille 9, D-22767 Hamburg, Germany
[2] Univ Kiel, Dept Econ, D-24118 Kiel, Germany
[3] Oxford Martin Sch INET Oxford, Inst New Econ Thinking, Oxford, England
[4] Zentrum Mat & Kustenforsch GmbH, Helmholtz Zentrum Geesthacht, Max Planck Str 1, D-21502 Geesthacht, Germany