Bottom trawling is a fishing method which involves dragging weighted nets across or in close proximity to the seafloor. Trawl nets range in size and can be as large as the wingspan of an aeroplane.
Devices such as heavy steel trawl doors and ropes are attached to the nets. The trawl doors dig into the benthic environment as the nets are dragged along the seafloor. The trawl doors act like sheep dogs, herding fish into the path of the net so eventually the fish end up in the back of the net.
The large nets used in bottom trawling collect everything herded by the trawl wake.
There are two kinds of bottom trawling – benthic and midwater. Benthic trawling occurs on the seafloor whereas midwater trawling occurs slightly above the seafloor.
Fish and other flora and fauna gathered in the trawl nets are then brought up to the surface to be processed.
A bottom trawling episode can occur over several hours depending on the area fished and target species.
