Abrasion is associated with bottom-contacting mobile and set fishing activities, in particular scallop dredging, beam trawling, and otter trawling and other activities such as anchoring, hydrodynamic dredging, and cable burial.
Physical disturbance of benthic habitats by bottom trawl fishing gear is described by using vessel monitoring system (VMS) and logbook data. The extent, magnitude, and impact of mobile bottom-contacting fishing gear on the seabed and benthic habitats varies geographically across the Celtic Seas (Figure 4). This figure excludes Spanish fishing effort. Fishing is mainly concentrated along the shelf edge, i.e. around the southern shelf regions and on fishing grounds in the Irish Sea and to the west of Scotland.
Using vessel monitoring system (VMS) and logbook data, ICES estimates that mobile bottom trawls used by commercial fisheries in the 12 m+ vessel category have been deployed over approximately 409 425 km2 of the ecoregion in 2018; this corresponds to ca. 44.6% of the ecoregion's spatial extent (Figure 5).
Figure 5: Average annual surface (left) and subsurface (right) disturbance by mobile bottom contacting fishing gear (Bottom otter trawls, Bottom seines, Dredges, Beam trawls) in the Celtic Seas during 2014–2017, expressed as average swept area ratios (SAR).