Fishing with gill net tools is the type of fishing that requires the most experience, with regard to the behaviour of the species that can be fished in the different seasons. This fishing is performed by fishermen who have a profound "culture" of the sea. The quantity of catches made depends on this culture of theirs.
This is the most well-known of the gill nets. It consists of three pieces. The two external pieces are identical and are formed by net with very large mesh, while the mesh of the inner part is much smaller. The fish that come across the net, try to go through the large mesh of the external part, but remain trapped inside the internal part. The trammel net is generally lowered down to the seabed to catch valuable species. The catch takesplace by sacking-up.
The fish that encounters this net and attempts to pass through it, squeezes through the external larger-meshed net and finds itself before the abundant smaller-meshed net on the inside. Intent on passing through it, the fish advances in the opposite direction from the one he came from, dragging some of the internal meshed net with him into the piece of meshed net located on the opposite side, thus forming a sack inside which he is trapped.