Submarine canyons are biodiversity hotspots and key ecosystems, connecting shallow and deep environments and sustaining valuable fisheries. Among the fishing techniques, bottom trawling is the most harmful due to its effects in overexploitation, habitat destruction, physical and biogeochemical alterations of the seabed. Along the NW Mediterranean continental slope, deep-sea trawling is practiced recurrently, mainly targeting the deep-sea shrimp Aristeus antennatus, fished at 500-800-m depths.

Along the Catalan margin, the impacts of bottom trawling activities on the Palamós (also known as La Fonera) submarine canyon have been studied for years. The negative effects of this fishing practice were transferred by the scientific community to the fishing sector, and as a result, in 2013, the Palamós fishers guild initiated a self-regulated endeavor, to conduct a more sustainable fishery and protect fishing grounds along the canyon flanks. In late 2017, all trawling vessels from the Palamós harbor changed their gear to minimize the contact with the seafloor. But so far, several years after the introduction of such management measures, no comprehensive research study was conducted to assess their effectiveness in reducing the physical, biogeochemical, and ecological impacts on the seafloor.

Here, meiofaunal assemblages from the Palamós Canyon were analyzed, in terms of abundance, biomass, richness of taxa, and taxonomic composition, comparing two sampling times (2011 vs 2024), before and approximately 7 years after the trawling fleet gear reconversion. The results indicate significantly higher abundance, biomass and richness of taxa in 2024 than in 2011, both in trawled and reference stations, with higher enhancement in trawled conditions. In 2024, total meiofaunal abundance decreases with increasing sediment depth, unlike 2011. Also, taxonomic composition significantly differs between sampling times, with dissimilarity between trawled and untrawled conditions lower in 2024.

These preliminary results suggest that the reduction of bottom-trawling pressure after the trawling gear change could effectively promote the recovery of deep-sea meiobenthic assemblages, although long-term assessments are required to study the possible resilience of deep-sea ecosystems.