Modelling economic response to harvest and effort control in North Sea cod fishery

A number of European fishing fleets have been regulated through a combination of quota and effort (sea days) controls since 2004. These two regulation schemes are, however, interrelated, i.e. a given quota limit will necessarily determine the effort used and vice versa. A bioeconomic feedback model is presented which takes this causality between effort and harvest control into account, and switches back and forth between these two regulation schemes depending on which is the binding rule. The model is based on biological stock projection, and quotas are set using the Pope approximation while an economic production function is used to estimate the harvest when the effort is binding. The economic response of the fleet is modelled through a dynamic investment/disinvestment module which evaluates the change in the fleet capacity given the economic outcome of the fishery. A simple example is presented for the Danish seiners catching cod in the North Sea. The model has been constructed as part of the 6th framework project “Operational Evaluation Tools for Fisheries Management Options (EFIMAS)”

The marine ecosystem services approach in a fisheries management perspective

This paper reviews the concepts of marine ecosystem services and their economic valuation in a European fisheries management perspective. We find that the concept is at best cumbersome for advising on how best to regulate fisheries even in an ecosystem context. We propose that operational fisheries management must consider three different types of analysis, the yield of and the effect of fishing on the commercial species, the effects of fishing on habitats and non-commercial species and finally an overall analysis of the combined impact of all human activities on the marine ecosystem. We find that the concept of marine ecosystem services is not helpful for the two first mentioned types of analysis and that a cost-benefit analysis that is implied by the marine ecosystem services concept is inadequate for the third. We argue that the discussion needs to be divided into two: (1) finding the boundaries within which we accept impact on the marine ecosystem and (2) within these boundaries find the optimal fishing pressure, in mathematical terms replacing the unconstrained optimisation implied by the ecosystem services concept with an optimisation with constraints. The constraints are defined as to avoiding social unacceptable solutions