Non-cooperative exploitation of multi-cohort fisheries - The role of gear selectivity in the North-East Arctic cod fishery
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Diekert, F.K., Hjermann, D.Ø., Nævdal, E. og N.C. Stenseth
North-East Arctic cod is shared by Russia and Norway. Taking its multi-cohort structure into account, how would optimal management look like? How would non-cooperative exploitation limit the obtainable profits? To which extent could the strategic situation explain today’s over-harvesting? Simulation of a detailed bio-economic model reveals that the mesh size should be significantly increased, resulting not only in a doubling of economic gains, but also in a biologically healthier age-structure of the stock. The Nash equilibrium is close to the current regime. Even when effort is fixed to its optimal level, the non-cooperative choice of gear selectivity leads to a large dissipation of rents.
Differential game; Gear selectivity; Multi-cohort fisheries; North-East Arctic cod; Optimal harvest policies