Approach

TrawledSeas will be carried out in eight study areas within major fishing grounds: the Catalan margin, the Malta Plateau, the Norwegian margin, the Canterbury margin, the Sicilian margin, the Patagonian margin, the Barkley Canyon and the Ireland margin. These areas are representative of the most prevalent types of continental margin (siliciclastic, carbonate, volcanic and glacial) and most of them are incised by submarine canyons.

Map of known trawling grounds (in red) on the world  continental  slopes. Study  areas  are  denoted  by black boxes: S1: Catalan margin. S2: Malta Plateau. S3: Norwegian  margin.  S4:  Canterbury  margin.  S5:  NW Sicilian  margin.  S6:  Patagonian  margin.  S7:  Barkley Canyon. S8: Ireland margin. Modified from Puig et al., 2012.

The  primary  dataset  for  the  project  will  be  multibeam  echosounder  data  from  hull-mounted  (MBES)  and autonomous  underwater  vehicle  (AUV)  systems,  which  allow reconstruction  of  seafloor  topography  in  3D (bathymetry) and provide clues on sediment grain size and seabed hardness (backscatter). This dataset will be complemented by additional high-resolution geophysical and field data, including: (i) side scan sonographs, to identify and map individual trawl marks; (ii) surficial sediment samples, to assess the impact of trawling on the sediment type and sorting, (iii) sediment cores, to date bottom trawling activity and estimate deposition rates; and (iv) seafloor imagery acquired from Remotely Operated Vehicles (ROV) dives, to provide georeferenced visual evidences of bottom trawling at fine scale. These data will be provided by a strong partnership. Satellite-based Vessel Monitoring System (VMS) and high resolution Automated Information System (AIS) vessel tracking data will provide an indication of trawling location and intensity in each study area.

TrawledSeas is based on an interdisciplinary approach that combines concepts and methods from geomorphology, geophysics, sedimentology and geostatistics. A main component of the methodology consists of the geomorphometric analysis of high-resolution multibeam data, implemented in a Geographic Information System (GIS). A new automated marine landscape mapping technique will be developed to detect, map and quantify morphological changes caused by bottom trawling on the deep seafloor.