MEDISIS Hake Fisheries Dynamics Model for the Gulf of Lion

Recent reconversion from pelagic to demersal fishing activity and intense fishing effort has led to large scale declines in Mediterranean European hake (Merlucius merluccius) populations. However, to date, a lack of understanding in spatially explicit fisheries dynamics raises uncertainty in how management under the 2020 Northwest Mediterranean management plan will impact hake, and what this will mean for fisheries. Here we introduce a spatialized, fisheries bioeconomic deterministic simulation model, ISIS-Fish, parametrized for the hake fisheries in the Gulf of Lion, European Management Unit (EMU1). We assess the impact spatio-temporal closures, effort reduction, and mixed measure regimes will have on rebuilding stock levels and reducing juvenile catch, while demonstrating potential impacts on gross revenues. The robustness of scenario comparison is assessed through an uncertainty analysis accounting for alternative hypotheses on recruitment, connectivity between population zones, and initial abundance levels. Our findings show not only that effort reduction can be more effective in achieving hake population recovery goals, but also that spatio-temporal closures were disappointing in that they failed to meet management objectives for hake. We further raise obvious equity questions in the application of the WestMed management plan where a trade-off has to be found between countries and fleets. This is also presented in relation to a publication with Fisheries Research to allow for further transparency. Therefore when using this data please also cite its corresponding publication.