Global ghost fishing characterization model for derelict bottom set gillnets

Ghost fishing, the unintended capture of marine life by abandoned, lost, and discarded fishing gear, is a major driver of biodiversity loss in the marine environment. Among major fishing gear types, derelict gillnets are widely considered to pose the greatest threat to marine biodiversity. However, impact indicators quantifying the ghost fishing damage caused by derelict bottom set gillnets on fish and invertebrate biodiversity are currently unavailable. In this study, we propose global and Norwegian characterization factors for use in life cycle assessment to quantify the impacts of derelict bottom set gillnets on fish and invertebrate biodiversity within the ecosystem quality Area of Protection. Generalized linear mixed-effects model results indicated that invertebrates and cartilaginous fish experienced stronger impacts and exhibited greater susceptibility to ghost fishing than bony fish species. The global ghost fishing characterization factor for derelict bottom set gillnets was 5.74 × 10 −13 PAF.yr/m 2 under the best, 7.01 × 10 −13 PAF.yr/m 2 under the intermediate, and 2.27 × 10 −12 PAF.yr/m 2 under the worst-case scenario. In the Norwegian exclusive economic zone, the characterization factor was 8.54 × 10 −11 PAF.yr/m 2 under the best, 1.57 × 10 −10 PAF.yr/m 2 under the intermediate, and 4.58 × 10 −10 PAF.yr/m 2 under the worst-case scenario. This study presents the first characterization factors quantifying fish and invertebrate biodiversity loss caused by derelict bottom set gillnets, providing a first-order estimate based on currently available data and identifying key limitations for future refinement.