The more the merrier? Testing spatial resolution to simulate area closure effects on the pelagic North Sea autumn spawning herring stock and fishery

Spatially explicit bio-economic models that are age-structured and dynamic become increasingly important, being used for different purposes including spatial management measure evaluation. One of the reasons why those complex models are still rare is the extensive data need. FishRent incorporates highly resolved economic information of multiple fleets at the same time linking this to a detailed age-structured biology of multiple species simultaneously. Additionally, it follows the European Data Collection Framework (DCF) data structure, hence the data is relatively easy to implement We adapted the temporal (annual) version of the pelagic FishRent model to be spatially explicit and incorporated seasonal migration patterns of North Sea herring. During this process, we showed the effects of increasing the spatial resolutions on simulated stock biomass and simulated fleet behaviour. When interested in the general, annual population development over the years, a relatively low resolution might suffice. Spatial effects of the fleet behaviour are, however, better captured with a higher resolution. Further, we closed the major spawning grounds at different resolutions. By doing so, we illustrated the need to incorporate a dynamic behaviour of fishing fleets and to increase fleets’ flexibility by increasing the amount of accessible areas for each fleet.