Ecological and economic effects of banning bottom trawling in Natura 2000 sites and reducing its effort in the western Mediterranean

In the Mediterranean Sea, several fished stocks remain overexploited and several marine protected areas (MPAs) permit high-impact gears such as bottom trawling. Improving understanding of the effects of stricter MPAs and reductions in fishing effort is essential to progress towards biodiversity and sustainable fisheries targets. Here, we use a marine ecosystem modelling approach to assess the potential ecological and fishery-related economic effects of three management scenarios involving a ban of bottom trawling in Natura 2000 sites designated under the Habitats Directive (hereafter SACs) and reductions of bottom trawling effort in the north-western Mediterranean Sea. Our results indicate that implementing the spatial ban alone can lead to increases in revenue and catch of key demersal species (reflecting potential fisheries spillover) outside SACs, particularly in the buffer zones, while delivering ecological benefits within SACs compared to a business-as-usual scenario. Instead, reducing bottom trawling effort overall can enhance demersal biomass recovery over both short and long-time scales, across the study area. Combining both management actions can deliver ecological benefits for key demersal species over both short and long-time scales within and outside SACs, and potential fisheries spillover in the buffer zones. Our findings underscore the importance of banning bottom trawling within SACs as a key step to support demersal community recovery and advance biodiversity objectives. They also highlight that no single management measure can simultaneously maximize ecological benefits and fisheries catch and revenue: combining spatial protection and effort-based regulation may be required to balance biodiversity and fisheries objectives and ensure long-term sustainability of the Mediterranean Sea.