It appears that the role of ecological constraints in determining viable management strategies is weak as compared to economic constraints. This is confirmed by assessing the impact of the ecological constraints on the different strategies u , through calculation of the difference between the probability of economic viability and the probability of co-viability. This difference is zero for the three scenarios and it suggests that the marginal impact of the ecological constraints is weak. In other words, given the bio-economic situation of the fishery as captured in ther model for the late 2000s, sustainability risks in the fishery are rather economic
The status quo strategy is not economically viable. This outcome holds especially true under a most likely scenario where fuel increase projection are taken into account. The results indicate that, given the status of the species and fleets in 2008, and the nature of the technical interactions between fleets, there appears to be excess capacity in the fishery as a whole. All alternative management strategies tested lead to some reduction in the capacity of the fleets.
The net present value (NPV) strategy achieves its objective of maximizing high level of economic performance for the overall fishery. Despite the management systems in place, and a series of decommissioning plans which have been aimed at reducing the capacity of these fleets, the fishery seems far from realising potential Maximum Economic Yield objective. Our approach provides an explanation for this, based on the observation that a strategy aimed at maximizing the Net Present Value of profits derived from the fishery as a whole, would actually lead to quite heterogeneous impacts on the fleets and sub-fleets. The NPV strategy leads to stop certain sub-fleets entirely from fishing,(larger Nephrops trawlers, various fish trawlers and certain sub-fleets of Sole gill-netters). Such an outcome is a direct result of the differences in economic efficiency between sub-fleets and technical interactions between them that were assumed in the model.
The co-viability (CVA)strategy can be achieved by a number of combinations of capacity adjustments, which all allow the ecological and economic viability constraints to be met for all species and sub-fleets. The strategy however also points to the need for a global reduction of capacity even if reallocations in effort are not quite as drastic as the one suggested by the NPV strategy, and allow some activity to be maintained in all sub-fleets. This strategy might be expected to more easily achieve consensus among the multiple stakeholders involved in the fishery. Circumstances under which such a strategy might be expected to be more easily adopted would be where the owners of vessels belonging to the sub-fleets which remain active and benefit from the adjustment could buy-out or compensate the owners of those vessels that are requested to leave .The assumption of increasing fuel price, which is likely to occur, is detrimental to the bio-economic outcomes of simulations, however, it does not change the nature of the qualitative outcomes and analysis.