Also known as “dragging,” bottom trawling uses a large net made of polyethylene to catch fish. Steel or wooden doors spread the net open. Floats are attached to the upper mouth of the net to keep it open vertically and weighted “bobbins” are attached to the lower mouth to sink the net. The bobbins’ design depends on the terrain, varying from small rubber discs for smooth sandy seafloors to large metal balls for rough ground. Known as “rock hoppers,” bobbins lift the net over obstacles on the seafloor.
In Atlantic Canada, many different groundfish species are incidentally caught in bottom trawls. These include halibut, haddock, cod, hake, redfish and pollock, among others. Each year, about 60 to 70 trawlers under 65 feet (20 metres) actively participate in the groundfish fishery. In total, 305 trawlers under 65 feet are licensed to catch groundfish.