Linking marine litter from land sources to its spatial distribution on fishing grounds in the NW Mediterranean Sea

Marine litter (ML), predominantly originating from land, tends to accumulate on the seabed, where it is often caught unintentionally by bottom trawlers. This study aims to characterize the benthic ML on NW Mediterranean fishing grounds and examine the relationship between land-based sources and the ML spatial distribution. Marine litter was collected onboard commercial bottom trawlers operating along the Catalan margin. Plastic was the most abundant fraction of litter, accounting for up to 63% of the total weight. The key factors influencing the spatial distribution of ML included sampling area, proximity to river mouths, and distance to submarine outfalls. The influence of the fishing effort on the spatial distribution of ML was also analyzed, but no significant correlation was identified. Higher ML concentrations were found in front of Barcelona (up to 201.94 kg km²), while lower amounts were observed in northern and southern boundaries of the study area. The results emphasize the need for better land waste management strategies to reduce litter accumulation in fishing grounds.