Standard Operating Procedures of Deep Sea Beamtrawl

Abstract

Beam Trawl net is a type of bottom trawl net. The target catches of beam trawl is coastal shrimp. The beam trawl fishing has been recorded of the operation in Thailand since 1957. It is the prototype of the other bottom trawls in the Thailand. Thai fisherman always spread operated the small beam trawl along the coastal fishing ground of Thailand. The fishing boat is 6-8 m. length equipped with 7-8 horse power outboard engines in the few decades. Now a day, fisherman in the inner and central part of the gulf of Thailand, Samutsakorn and Chumporn provinces, have enlarged their fishing boat to be 14-18 m. with 200-300 horse power inboard engines. Only fisherman in the Southern part of the Gulf of Thailand still have operated the conventional small scale of beam trawl. Beam trawls are one type of fishing gear designed on use on the sea bed. A beam trawl consists of a cone-shaped body ending in a bag or cod end, which retains the catch. In these trawls the horizontal opening of the net is provided by a beam, made of wood or metal. The vertically opening is provided by two hoop-like trawl heads/shoes mostly made from steel. No hydrodynamic forces are needed to keep a beam trawl open. While fishing for flatfish the beam trawl is often equipped with tickler chains to disturb the fish from the sea bed. For operations on very rough fishing grounds they can be equipped with chain matrices are rigged between the beam and the ground rope and prevent boulders/stones from being caught by the trawl. Shrimp beam trawls are not so heavy and have smaller mesh sizes. A bobbin of ground rope with rubber bobbins keeps the shrimp beam trawl in contact with the bottom and gives flatfish the opportunity to escape.