A quantitative risk assessment approach for longline fishing gear impacts on seafloor habitats

Abstract Bottom longline fishing gear used worldwide to capture fish and invertebrate species can impact seafloor habitats, leading to increased use of spatial closures (e.g. Marine Protected Areas) in areas where habitat risks are considered high. However, such closures often rely on limited data, because fishing impacts on habitat are rarely quantified and habitat maps are often unavailable. We demonstrate a quantitative risk assessment framework for habitat impacts from bottom longline trap and hook fisheries and develop species distribution models for coral and sponge habitats, using the British Columbia sablefish fishery as a case study. We estimate a 4.5% (95% confidence interval: 2.8%–6.9%) overall reduction in sponge habitats due to sablefish fishing from 1965 to 2024, compared to pre-fishery levels. Habitat status for 1 km × 1 km grid cells showed similar trends to the overall status, with habitat declines