5.1 Otter Trawl

          The otter trawl is classified into three types depending on the size of boat, namely; baby trawl (less than 3 GT), medium-sized trawl (3 GT -20 GT), and Launch type trawl (greater than 20 GT). All three types use otter boards to open the net mouth.
           The baby trawl is operated by outriggered motorized bancas 7 to 10 m long, usually powered by 16 Hp gasoline engines. It is operated in municipal waters at depths from 5 m to 15 m. Target specie are shrimps, fish and other invertebrates. There are two net designs employed. The most common is the V-shaped net where cutting is mostly all bars and the length is about 13 m. The groundrope is usually longer by 1 m than the headrope. The common mesh size ranges from 20 to 30 mm. The wooden otter board measures 97 cm long x 33.5 cm wide. Operation is conducted by 2 to 3 fishermen. The second design resembles the two-seam trawl net for the medium and launch type trawls. The cutting rates for each panel vary with the combination of mesh-bar cutting. It has a length of 15 m and mesh sizes from 20 to 35 mm. The otter board is similar in size and shape to the board used by the shrimp baby trawl net. The groundrope is longer than the headrope by about 2-6 m.
           The medium-sized trawl nets are also operated by outriggered bancas but they are bigger. The boat, or banca, is 10 to 13 m long and is powered by 80 to 225 Hp diesel engines. The main deck flooring is made of marine plywood. A platform is provided at the stern where setting and hauling of the net takes place. It has an after mast for tying the towing warp while dragging. Many designs are used by the fishermen. Some nets have no overhang while others have short wings. The net has a length range of 30 to 50 m and uses a combination of polyethylene netting in the wings and bellies while nylon multifilament and kuralon is used in the lower portions. The mesh sizes range from 203.2 mm in the wings to 19.05 mm in the bunt. The otter boards are rectangular and flat, made of wood but iron bars are placed on the lower side to add weight. Its length varies from 100-200 cm and is from 50-100 cm wide. Most of the medium-sized trawls are two-seam and the fish caught during daytime are slipmouths, hairtail, squid, and squilla. These trawl nets are mostly operated in Manila Bay. The Visayan Sea, the Samar Sea and Carigara Bay.
           The launch-type trawl net is primarily used to capture demersal and semi-pelagic species. It is operated by wooden or steel-hulled boats with mechanical or hydraulic winches, niggerheads, booms, strapping blocks and trawl gallows. A majority of the boats are equipped with fish finders and the bigger sized-boats have radar. The boats are usually 14 to 30 m long, and are powered by one or two engines. Commonly used is the lzusu 120 to 180 Hp or 280 to 360 Hp Cummins, Yanmar or Caterpillar engines. The material for the bigger-sized nets is polyethylene ranging from 400d/15 to 400d/48. Others use nylon material.
            In the Lingayen gulf, trawlers operate their nets at depths from 50 to 80 m. The otter boards vary from 1.4 to 1.6 m long by 70-80 cm wide, wooden and are of a rectangular flat shape. The sweeplines have a length of 72 m and are attached to the upper and lower ends of the wings. The Damortis trawlers are powered by 120 Hp Izusu engines. Setting and hauling the net is done from the stern. The Niggerhead, or drums, located on both sides, facilitate the hauling of the net. Species caught are slipmouths, hairtail, caranx, goatfish and nemipterids.
           In Manila Bay, trawlers operate near the Batanna and Corregidor coastal areas at depths from 30 to 60 m. These trawlers stay in the area for 3 to 5 days and are equipped with a capstan winch to haul the warps and for lifting the catch on board. Most vessels are comparatively larger than the medium-sized bancas and have engines ranging from 180 to 300 Hp. The two-seam type of net is used, with 160 mm –300 mm mesh sizes, using nylon twine of 210/33 to 210/72 and 24 mm mesh size. The otter boards which are made of rectangular wood measuring from 100-112 cm wide and 200-230 cm long. Their weights vary from 80 to 150 kg each. Major species in the area are rastrelliger, anchovy, hairtail, squid, slipmouth, and croaker.
              In the Visayas area, trawlers are primarily used to catch demersal and semi-pelagic species. Most trawlers at Roxas City, Catbalogan, Carigara, Estancia and Cadiz are made of wood. Big steel-hulled trawlers are common at Iloilo and Bacolod Cities. The wooden vessels are equipped with fish finders and compasses and also stay at sea until the fish holds are full or their provisions are becoming low. The steel hulled trawlers stay longer at sea. Some fishing boats have accompanying fish carriers to take their catch to the market and to replenish provisions when they return. Most of the nets are two-seam type with sizes ranging from 1 to 2 m in the wing section and 30 to 40 mm in the cod-end. Setting and hauling the net is mechanized, so that 4 to 5 operations can be done in one day. Major species caught are nemipterids, hairtail, caranx, pompret, goatfish, lizardfish and other demersal species. Semi-pelagic fishes also contribute to trawler production.