Working Group on Fisheries Benthic Impact and Trade-offs (WGFBIT; outputs from 2024 meeting)

The Working Group on Fisheries Benthic Impact and Trade-offs (WGFBIT) develops methods and assessments to evaluate fisheries’ benthic impact at a regional scale while considering trade-offs between fisheries and seabed health. This report summarizes progress on a European-wide assessment of bottom trawl impacts, presenting the first quantitative evaluation across the Baltic, Atlantic, Mediterranean, and Black Seas. Using indicators of seabed status—RBStot (biomass rel-ative to fauna carrying capacity) and RBSsen (biomass of the 10% most sensitive fauna relative to carrying capacity)—significant regional and habitat differences in bottom trawling impacts were identified. Methods to differentiate between good and degraded states were further re-fined, including probability-based approaches for seabed condition assessment. A roadmap was established to implement a Core Fishing Grounds Analysis (CFGA) across all EU marine regions within the 2024–2027 cycle. CFGs aim to balance sustainable fishing and en-vironmental goals by protecting high-value fishing areas. Discussions addressed current limita-tions of CFGA and guidelines for defining scenarios in trade-off analyses. A preliminary exercise using Atlantic and Mediterranean data explored the effects of varying RBS values on surface area, landing value, fishing effort, and weight. Assuming RBS = 0.8 as the threshold for a "good" condition, the study assessed reductions in exploited areas and fishing efforts needed to meet EU marine targets (D6C5 Adverse Effects on Habitats). The BFIAT (Bottom Fishing Impact Assessment Tool) model was advanced to predict trawling-induced habitat changes and their impact on biological processes like bioturbation. Case studies in the Celtic Sea, Greek waters, Baltic Sea, and Kattegat utilized datasets linking macrofauna traits to biogeochemical processes under different fishing and hydrodynamic regimes. Outputs from BFIAT are integrated with models like OMEXDIA to evaluate sediment carbon processing and with 3D models (NEMO/SPM-IOW, NEMO-ERSEM) to analyze carbon dynamics and dep-osition. Future work will examine the impacts of fauna reduction, sediment mixing, and carbon decay on ecosystem processes