A fishing net that consists of single, double or triple netting walls that hang in the water column, typically made of monofilament or multifilament nylon. Mesh sizes are designed to allow fish to get only their head through the netting, but not their body. The fish’s gills then get caught in the mesh as the fish tries to back out of the net. These nets can be used either alone or, as is more usual, in large numbers placed in line (“fleets” of nets). The gear can set, anchored to the bottom, or be left drifting (driftnet), free or connected with the vessel.