Bottom trawl fishing footprints on the world?s continental shelves

AMOROSO, RICARDO O.; PITCHER, C. ROLAND; MCCONNAUGHEY, ROBERT A; PARMA, ANA M; SUURONEN, P.; EIGAARD, OLE R.; BASTARDIE, FRANCOIS; HINTZEN, NIELS T.; ALTHAUS, FRANZISKA; ET AL (45 AUTORES)

Congreso; 5th International Marine Conservation Congress; 2018

Bottom trawl fisheries are an important source of seafood and em-ployment, but the disturbance on seabed habitats and benthic communities occasioned by the gear is a major environmental concern.An ecosystem-based fisheries management thus requires a detailedassessment of the extent and spatial distribution of fishing activities. However, the intensity of trawling is often reported at a coarsespatial scale, which creates a distorted picture of the total area impacted by fishing. We quantified the bottom trawling footprint usinghigh-resolution satellite Vessel Monitoring System (VMS) and log-book data on 24 continental shelves and slopes to 1000 m depth forthe period 2008-2010 (with few exceptions). The trawling footprintwas markedly different among regions ranging from less than 10% tomore than 50% of the seabed area. In 18 regions, more than two thirdsof the seabed was not trawled. The footprint area was very sensitiveto the spatial scale of the analysis; in the most extreme case the foot-print increased from less than 1% of the area on a 1 km2 cells grid to~60% on a coarser grid of 100 km2 cells. Within the footprint fishingeffort aggregated in areas intensively trawled. On average, 90% ofthe activity comprised 77% of the total footprint area. We found thatthe swept-area ratio (ratio of total swept-area trawled annually to thetotal area of a region) was a good predictor of the proportion of theseabed trawled, allowing estimation of regional trawling footprintswhen high-resolution spatial data are unavailable