This study was conducted through several field surveys in the SME waters covering three administrative ranges. The SME is located between longitudes 89°00’ E and 89°55’ E and latitudes 21°30’ N and 22°30’ N at the south-west of Bangladesh, encompassing mouth of the 6 estuaries, and numerous rivers, canals and creeks.
The study was conducted through 24 individual surveys in the SME of Bangladesh covering 16 rivers/canals and 32 locations (one-third area) of the Sundarbans along the Mongla-Passure-Dubla area within Sharankhola, Chandpai and Khulna ranges between January and December 2006 at fortnightly interval.
4 Methods of Giant Freshwater Prawn Fishing in SME
4.1 Mode of Gear Operation
Hookline: The Hookline is a baited gear generally used by a single fisher per boat in rivers, small rivers and canals during spring tide phases throughout SME. It is used with small rod (stick), hook and line. About 4-7 sticks with hooks are employed to catch giant freshwater prawn in the SME. Hooks of various numbers, generally 12 in number each with 2-2.2 cm in height are employed. It is operated in daytime, mainly during high tide for 5-6 hrs/day. The fishermen mostly avoid operating this gear during night mainly due to insecurity.
Behundi jal: It is a larger version of the Patajal used to catch small fish and crustaceans which are weak swimmers. It is usually set towards the center of the river channel, and rarely near the shore. Hence no external anchoring is used. It is hauled twice a day, only during low tide phases. The catch is quite low; juvenile shrimp constitute about 98% of the catch, the rest are juvenile finfish. It is set in every month in the small rivers of the Sundarbans areas during the time of spring tide. This net is set 2-3 times in every 24 hours. Nets are set against the current by fastening the wings to a pair of heavy wooden anchors in deeper water areas, or two wooden poles in shallower water. The mouth of the net is kept open by 2 bamboo poles fastened to the upper and lower lips of the mouth of the bag. A wooden barrel is tied to each end of the wing to serve as a buoy. The cod end is tied with a rope and a float is also attached to it to know the location. A small Balam boat with two men is required to set the net. Hauling is done when the tide runs and after emptying the contents may again be set against the prevailing tide. The fish comes with the tidal current, enters through the mouth and ends up in the bag. The catch consists of crabs, shrimps and many kinds of fresh and brackish water fishes. This net is highly destructive for juvenile fish, shrimp and crab species.
Charpata jal: It is operated in the rivers and khals of the SME. The net is potentially very effective (i.e. destructive) in small rivers and khals, as it is capable of catching virtually all fish, irrespective of size, present in a Khals. The catch composition (i.e., Lates calcarifer, Plotosus canius, Scatophagus aurgus, Jhonius spp., Mugil spp., Arius spp. etc.) is quite different from that of set bagnets. It is used during spring tide. It is set in the intertidal zone of the rivers of the Sundarhans. The net is placed once in a day and it remains under water during high tide. Poles are fixed during low tide along the lowest low tide line and the net is kept folded and embedded into the mud on the ground. The stout ground rope is tied to the poles at the base. The head rope also may be tied above in some places to facilitate the lifting of the net later on during high tide. Food is given when the water of the tide rises on the net from 1 to 1.5 in high; 4 to 5 kg of the rice particles, rice bran and sago are mixed with water and the mixture of these items is applied in the water as the food to attract fish. When high tide has reached to the maximum, fishermen go by boats, raise the net and tie the head rope above the level of water. Two to three fishermen are engaged to operate this net. When the tide turns and water recedes, the crabs, prawns and fishes are stranded and gathered.
Khalpata jal: It is similar to the Charpata jal in length and mesh size but slightly larger in breadth measuring about 4 m. It is a rectangular net of 30-40 m in length, 2.5-3 m in breadth and 2-4 cm in mesh size, operated in estuarine creeks or khals in the Sundarbans.
Gillnet: It is circular in shape and catches fish by gilling or entanglement. Gillnets are anchored to the bottom so that they are not free to move with the water current. They are usually set in rivers and estuaries before high tide. Sometimes the net may serve as a barrier. The fish and crabs get entangled in its meshes. The length of the net depends on the amount of capital available to the operator
Chandijal: It is a set gill net designed for large open water bodies to catch mainly Hilsha during May to October. It also used for fishing Shylong, Rui, Catla, Mrigel, Kalbasu, etc. It is made of several rectangular shaped 11-12 m pieces; jointed together. The mesh size of the net is 1.75 to 5 cm. Both sides of the net are locked with heavy nylon ropes along with floats and sinkers inversely. It is weaved with nylon and polyester fibers, and hanged with bamboo poles from both the side over water that can be operated by boat. The set gill net is operated by 5-10 fishermen at a time.
Badhajal: This is a type of set bag net, resembling a trawl net, set in the tidal stream by attaching it to holdfasts. It has a rectangular mouth kept open by two vertical bamboo poles. The net is held in a fishing position against the current by linking the extended sides of the net (wing tips) to hold-fasts by means of long bamboo poles and steel wires. The holdfasts are two wooden stakes embedded some distance apart in the sea bed, so that the net is parallel to the direction of the current.
Kathijal: It is locally known as “Jakhi jal” and also called “Khepla” or “Khepla jal”. It is a conical shaped net with variable size. The hauling string of the net is fixed at the narrow apical end of the cone. The lower end is folded, doubled up and attached to the net at intervals to form a series of pockets. The margins of the pockets are provided with iron weights as sinker. These nets are thrown into the shallow or moderately deep water from the shore bank or from a slow moving boat. As soon as it is thrown, it goes down quickly due to the weight of the sinkers. When the net is hauled the sinkers disturb the fish in the bottom and make them enter the pockets and are secured there. This net requires mostly smooth bottom for operation. All types of fish are caught by this gear.