1. Drift Gill Net

     There are many types of drift gill net used for different target species. Generally, their construction is a wall of net that is set across the water current and can be allowed to drift according to the current direction. The head rope is on the surface of the water or at the depth of 2 - 6 m. The lower part of the net is without sinkers or with a sinker line depending on the target species and the characteristics of the fishing ground.

     The length of gill-net depends on the size of boat, financial ability of fishermen and the target species. The average length of the gill-net is from 1 to 15 km and the nets that are used for catching small pelagic fishes such as sardine, flying fish etc are shorter than the drift gill-nets used for catching mackerel and tuna. The height of the gill net also depends on the target species and ranges from 2 to 20 meters. The mesh size used for catching small pelagic fishes like the sardine, flying fish etc. are from 30 to 50 mm. The main material for making the net is nylon monofilament with a diameter of 0.2 - 0.4 mm. For mackerel and tuna, the mesh size is larger ranging from 70 to 105 mm and the nets are mainly made of nylon multifilament of PA210D/12 -PA210D/18 and a few are made of PE380D/3x3 - PE380D/3x5.

     The Drift gill net is used mainly to catch pelagic fish, so that gill-netters usually are operated at night without moonlight (18" of this lunar month - 12 h of the next lunar one). The net is set at 3 - 5 pm and hauled the next morning.

    When the vessel is on the fishing ground, the skipper identifies the direction of water and wind, and decides a suitable direction for setting the net. Normally, the gill net is set or drifted making a certain angle between the water direction and the net. When setting, the vessel runs at a speed of 3 - 4 nm/h. After setting, one end of the net can be linked to the vessel or be allowed to drift freely according to the conditions of wave and wind in the fishing grounds.

Net Hauling:

     The part of the net drifting down wind is hauled first. In the hauling operation, the vessel can move in the direction of the net with a speed of 2 -3 kts according to the amount of fish trapped in the net. The hung fish are picked while hauling. The net is kept in the net hold after operation.