6.4 Trammel Net
Trammel net is not popular among fishermen in the country. It maybe that the removal of the catch is difficult when it is impounded by the inner layer of the netting. To address this problem, several modifications are being tried by the fishermen. The target species is the garfish which is very hard to catch using a single layer gill net.
The original design of trammel net consists of three layers. The two outer layers have the same twine and mesh size, and number of vertical and horizontal meshes, the hanging rate is more stretched than the inner layer. The inner layer has a smaller mesh size, finer twine and more slack. When the fish enter the first layer, they pass through eventually hitting the inner layer which envelops their bodies. They pass again to the 3rd layer where they are impounded. Trapping in the inner layer net does not allow the fish any chance of escape.
Other design consists of three layers of net, with the same twine, but different mesh sizes and hanging rates from the first layer, which has a bigger mesh size, and the last layer with the smallest mesh. Fish that will not be caught by the first or 2nd layer will be caught by the last layer. This design results in gilling rather than impounding the fish. Commonly used netting is the Nylon monofilament PA of 0.30 mm to 0.40 mm diameter and mesh sized at 76.2 mm (1st Layer), 50.8 mm (2nd Layer) and 38.1 mm (3rd Layer).
The behavior of the targeted species and ingenuity of local fishermen to devise a method of catching the garfish led to another modification by the use of two layer webbing. The first layer has a mesh size of 6.09 cm while the second layer has a mesh size of 4.35 cm with the same twine size PA of 0.30 mm monofilament. The first layer is hung at 51% while the second layer is 47% (direct method). This net is used in the Davao Gulf for catching garfish and other pelagic species.
Fishing operation of the three (3) types is similar. The net is set on schools of garfish by taking into account the fish and current directions. The net is set against the current, or where the fish is heading, while the scareline drives them towards the net. This gill net is usually set during daytime for garfish and at night time for other species.