midwater trawl

A midwater trawl is a type of fishing net that is towed through the water column between the ocean bottom and the surface to catch pelagic fish. This method involves dragging the net with one or two vessels, adjusting the depth by varying the length of the towing ropes and the speed of the vessel. A specialized device called a netsonde is used to monitor the trawl's depth and position relative to fish schools.1

In contrast, bottom trawling involves dragging a net along the seafloor, which can cause significant damage to marine ecosystems by disturbing and destroying bottom-dwelling species and their habitats. This method uses otter boards to spread the net's opening, and heavy chains may be used to disturb fish from the seabed into the net.21