Fishing and Gear Technology

Unit 11 - Trawl fishing gear and operation

11.3.Bottom trawling

11.3.4.Shooting of the net

As soon as reaching the fishing ground, one should observe the meteorological and hydrographical parameter such as direction and speed of wind, temperature, surface temperature, direction and speed of current, type of ground, depth of water, fishing position etc. Bring the vessel into lee word side and slow down the vessel with the trawler moving release the codend with forward motion of the trawler and then release throat portion belly followed by head rope and foot rope. Once the net is in the water, the sweeps and bridles connected to the otter boards are released with the vessel slowly steaming ahead so that net sweeps and bridles spread out and open properly. The otter boards are lowered to a few meters below the surface of water and kept for a few moments to ensure that they are spreading properly. The gear is then lowered to the desired fishing depth by releasing sufficient length of the both warps. The length of warp released during bottom trawling depends on the depth of the fishing ground, nature of sea bottom and towing speed of the boat. The ratio of depth of fishing ground and the warp released is known as scope ratio and is typically around 1:6 in shallow water up to less than 20 m, beyond 20 meter it would be 1:5 and in deeper waters it is 1:3.