Screen grab of underwater footage showing "trawl scars" left on the seabed in the wake of bottom trawlers.

The Arctic seabed at established fishing grounds already trawled looks like a moonscape, with all signs of life plowed away. The long drag mark is originating from the trawl net’s heavy planners that have been dragged alongside the trawl to keep the net open. The biggest bottom trawl nets measure about 70 metres in width and 100 metres in length.