Traditional and modern fishing crafts
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The document provides an overview of traditional and modern fishing crafts in India, categorizing them into non-mechanized and mechanized boats, and detailing various boat types like dugout canoes, plank-built boats, and motorized crafts. It outlines specific fishing techniques, including the use of gill nets, trawlers, and long lining, highlighting both the advantages and disadvantages of these methods and materials, especially fiber-reinforced plastics (FRP) in boat construction. The document also discusses operational details of different fishing gear and vessels, emphasizing their roles in commercial fishing.
Traditional and modern fishing crafts
- 1. Traditional and modern Fishing Crafts (UNIT IV Fishing Craft and Gear) TYBSc Semester V (Applied component – Marine Sci) Biren Daftary
- 2. Overview • Fishing crafts are essential for catching fish in large scale in the water bodies. • A variety of crafts have been designed for this purpose in India. • The fishing crafts of India fall under two general categories in India : Non-mechanised boats Mechanised boats
- 4. Dugout Canoe • Used for fishing within small distances from the shore • It is a small sized canoe made by scooping logs of wood in the form of a boat. • The “Odams”, “Thonies”, “Vanchies” etc. of the southeast and southwest coasts of India fall under this category. • In calm weather, oars may be enough for propulsion; but if winds and currents prevail, sails may be used.
- 5. • For travel in the rougher waters of the ocean, dugouts can be fitted with outriggers. • One or two smaller logs are mounted parallel to the main hull by long poles. • Outriggers help to balance the boat by providing support from one side or both the sides.
- 6. DUGOUT CANOE
- 7. OUTRIGGER
- 8. Plank-built boats • These are boats made by stitching together planks of wood. • There are also an enlarged variety of dugout canoe made of planks on the side, largely used in Kerala • In most of the plank built boats at present, the carvel type of boat is used.
- 9. Masula • Non-rigid boat constructed with planks sewn together with coir rope, but without any frames so as to withstand the severe knocking of the surfs. • They are made upto 9m in length, although generally smaller. • They are of various patterns viz. Bar boats in Orissa and Padava on the Andhra Coast
- 10. A variant with ribs inside has been developed in the area between Kakinada and Maslipatnam.
- 11. Carvel Boats • Carvel built or carvel planking is a method of boat building where hull planks are fastened edge to edge, gaining support from the frame and forming a smooth surface.
- 12. Dinghi and Nauka • These are carvel boats of Orissa and West Bengal Naukas, which are well designed and constructed up to a size of 13mx3mx2m are quite spacious and are used for a variety of purposes including fishing operations.
- 13. Tuticorin boats • These are also called the fishing luggers. They are carvel boats (11m x 2m x 1m), which are seaworthy in inshore waters. They are used more as mother ships and cargo boats than directly for fishing.
- 14. FRP Boats • The term FRP is generally accepted to mean fibre reinforced plastic. • It is composed of a series of reinforcements and liquid chemicals which when brought together in specific proportions can be formed into strong, solid but flexible shapes. • This FRP is then poured into a mould and when the FRP hardens it is cast out as a solid and strong hull.
- 15. • Different type of FRP boats can thus be built according to suitability by moulding them as the need be. • The most common type of the mould used is called as the female mould which is the mirror image of a finished hull. • The mould is made from a plug which is the exact hand crafted replica of the final hull.
- 16. • WOODEN PLUG→ FRP MOULD→FRP HULL • Thus it can be said that the first hull made from a new mould has been built three times.
- 18. Advantages & Disadvantages of FRP Advantages o Reduction of maintenance • No leaks. Hulls are one continuous piece of FRP with no joints or gaps to allow water into the hull. • No plank shrinkage when laid up. Wooden hulls suffer from plank shrinkage when brought out of the water and laid up in the sun. FRP does not shrink or swell so leakage and re-caulking are avoided.
- 19. • Rot proof and resistant to borers. FRP is non- organic and will not rot. As a plastic it cannot be eaten by marine borers. • Corrosion and electrolysis reduced. FRP is inert. As a plastic it will not corrode. o Simpler construction. Once a mould is made, identical copies of a hull can be made many times over and in a shorter time. o Reduction of skill levels required once a basic training is received.
- 20. Disadvantages • Total dependance on imported materials and foreign currency availability. • Choice of vessel fixed once design is chosen and moulds made. • Must retain core group of qualified technicians. • Fire and health hazards from chemicals. • Large start up investment.
- 21. Motorized Craft • With the advent of mechanization of the fishing crafts, small and medium sized boats are constructed with engines operated by oil to venture into distant fishing grounds. • These motorized crafts are: line boats, trap boats, dol netter, gillnetter and trawlers.
- 22. Hand line boat • Operated in both shallow and deeper waters. • Traditional hand liners use no winch. • The gear usually consists of a few meters of monofilament of 0.5-1mm diameter to the end of which is attached a hood and a sinker, usually a small stone. • They are used to catch all kinds of demersal fish from motorized as well as small mechanised vessels.
- 23. Trolling vessel • They tow lines extending on either side to catch pelagic species having high individual value and good quality such as Tuna. • The lures are attached to outrigger poles through lines that are towed by a slowly moving vessel. • The fished hooked after snapping at the lure are brought on board as the line is hooked in. • The vessel length vary and have a normal forward wheelhouse arrangement allowing a clear working deck.
- 26. Trawlers • A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. • Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. • Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. • A trawler may also operate two or more trawl nets simultaneously (double-rig and multi-rig).
- 27. • Modern trawlers are usually decked vessels designed for robustness. • Their superstructure (wheelhouse and accommodation) can be forward, midship or aft. • Motorised winches,electronic navigation and sonar systems are usually installed. • Fishing equipment varies in sophistication depending on the size of the vessel and the technology used.
- 28. Stern Trawler • On stern trawlers the trawl is set and hauled over the stern. • Stern trawlers are designed with or without a ramp, depending on the size of the vessel. • Stern trawlers are built for nearly all weather conditions. • Trawlers can work as single vessel in bottom or midwater trawling or as pair trawlers where two vessels tow one large trawl or a double trawl.
- 29. • The most common deck layout of a stern trawler is such that the wheelhouse is just forward of the midship with working deck behind. • The winch powered by the engine is located behind the wheel house with the warps leading to the gantry located at the middle or sides of the stern.
- 31. Outboard and inboard engines • An inboard motor is a marine propulsion system for boats. • As opposed to an outboard motor where an engine is mounted outside the hull of the craft, an inboard motor is an engine enclosed within the hull of the boat, usually connected to a propulsion screw by a driveshaft.
- 33. • An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the stern. • They are the most common motorized method of propelling small watercraft. • As well as providing propulsion, outboards provide steering control, as they are designed to pivot over their mountings and thus control the direction of thrust. • The skeg also acts as a rudder when the engine is not running. Unlike inboard motors, outboard motors can be easily removed for storage or repairs.
- 35. Mechanised craft and their various operations
- 36. Gill net • Gill nets are vertical panels of netting normally set in a straight line. • Fish may be caught by gill nets in 3 ways : (1) wedged – held by the mesh around the body (2) gilled – held by mesh slipping behind the opercula, or (3) tangled – held by teeth, spines, maxillaries, or other protrusions without the body penetrating the mesh. • Most often fish are gilled. • Gill nets catch fish that attempt to swim through the net, which are caught if their head passes through the mesh but not the rest of the body.
- 37. • The fish then becomes entangled by the gills as it attempts to back out of the net. • The mesh size used depends upon the species and the size range being targeted. • Gill nets may be set at or below the surface of water, on the sea bed or at any depth in between.
- 39. Bottom trawls • A bottom trawl is constructed like a cone-shaped net that is towed (by one or two boats) on the bottom. • It consists of a body ending in a cod end, which retains the catch. Normally the net has two lateral wings extending forward from the opening. • The mouth of the trawl is framed by headline and ground rope. It is designed to catch species living on or near the bottom. • Bottom contact with the gear is needed for successful operations.
- 40. • Three categories of bottom trawls can be distinguished based on how their horizontal opening is maintained: beam trawls, bottom otter trawls, and bottom pair trawls. • Beam trawls are commonly designed without wings • The ground rope equipped with rubber discs, spacers etc. protect the trawl from damage. On very rough bottom special rock hopper gears are used. • Trawl winches installed on deck control the trawling warps and store them when not in use.
- 41. • They are towed across the bottom at speeds ranging from 1 to 7 knots (0.5-3.5 m/s), frequently between 3 and 5 knots. • Duration of a tow mainly depends on the expected density of fish, the shape of the bottom and the slope in the fishing area, from a few mins upto 10-12 hours, commonly 3-5 hours.
- 43. Seine Netting • It is a bottom fishing method and is of particular importance in the harvesting of demersal or ground fish. • The fish are surrounded by a rope laid out on the seabed with a trawl shaped net at mid-length. • As the rope is hauled in, the fish are herded into the path of the net and caught • This method of fishing is less fuel-intensive than trawling and produces a high quality catch.
- 45. Purse seining • This is the general name given to the method of encircling a school of fish with a large wall of net. • The net is then drawn together underneath the fish so that they are completely surrounded. • It is one of the most aggressive methods of fishing and aims to capture large, dense shoals of mobile fish such as tuna, mackerel and herring.
- 47. Long lining • Long lining is one of the most fuel efficient catching methods. • This method is used to capture both demersal and pelagic fishes including swordfish and tuna. • It involves setting out a length of line as long as 50-100km long, to which short lengths of line carrying baited hooks are attached at intervals. • The lines may be set vertically in the water column or horizontally along the bottom.
- 48. • The size of the fish and species caught is determined by hook size and the type of bait used.
- 50. Squid Jigging • Jigging is widely used to capture squid. • A jig is a type of grapnel, attached to a line, which may be manually or mechanically jerked in the water to trap the fish in its body. • Jig fishing usually happens at night with the aid of light attraction • Squid jigging most often takes place at night with bright overhead lights to attract the squid.
- 51. • Jigs of various types, makes and colour are attached to the handline at 70 to 90 cm intervals. Often as many as 8 to 12 jigs are on one line. • The lines are lowered to 30 to 100 m depth depending on the strength of the lights used, but less deep on a small boat with one or two lamps. • It is important to keep the jig moving constantly in the water. This is usually done by jerking the line, quickly pulling in the slack, jerking once again and so on, until the jig is back to the surface
- 52. • The line is then thrown out and allowed to sink to the desired depth, and the same jerking motion is repeated over again. • Squids change colour as they move from shade to light and vice versa and are therfore difficult to see. • This explains why they can be difficult to catch and why jigging is most often the best method.
- 54. Bag net • Bag nets are containers made of nets that are dragged through the water, collecting the fish in its path. • The nets are usually held open by a frame and the water current.
- 56. Types of gill nets
- 57. Purse seines • It surrounds the fishes in vertical as well as horizontal position and is used for pelagic fishery. • The netting walls are long. • It weighs about 1.25-1.5 tonnes, is 450m long, 40-45m deep. • One end is joined to the main boat and other end encircles the area and two ends are brought together, the fishes are encircled and the net is pulled up. • Bout 20-25 people operate it.
- 59. Cast Net • Cast nets are popular variety of the small net operated by a single man. • It usually has a string. • The net is cast by the sweep of the arm • When it spreads the fishes are caught in it. • The commonly used one is called ‘Ghagria jal’, a circular or umbrellar net with the chord at the apex. • The iron weights are attached on the margin.
- 60. • When the net is thrown, it spreads, sinks and the weights make it close. • It is used for small fishes.
- 62. Rampani net • This type of seine net is operated from the beach or shore and hence the name. • The net is made up of one hundred to several hundred rectangular pieces joined together. • The net is formed of hemp. • Size of the mesh is smaller at the central portion than at the side portion. • Wooden floats are attached to the head rope and stone sinkers are attached to the foot rope.
- 63. • The net is operated by 60-80 men. • In the beginning a scouting boat known as ‘thoni’ is taken into the sea for a survey, and then as the shoal is sighted, a signal is given to the other members on the shore. • Immediately one end of the leading rope is handed over to the men on the shore and the net is carried by a larger boat called as ‘Pandi’. • The net is then laid out in a semicircular fashion and then pulled by both the groups of men.
- 65. Tuna Longline • Longlining is a passive type of fishing technique making use of lines with baited hooks as fishing gear. • The longline used for tuna fishing is made up of units each of which consists of a main horizontal line about 250 to 800 m long with 4 to 15 branch-lines, each with a wire leader and a hook. • The depth where the hooks are set in the water column is a crucial element, this depth in which the longline is settled can be regulated mainly by modifying the intervals of the main line between float lines and partially by adjusting the length of float-line and/or the speed of shooting, to a lesser extent, by modifying the length of the branch-lines.
- 67. Dol net • It is a bag net. Bag nets are conical bag like nets without wings. The size of the mesh increases from bag portion to the mouth of the net. • Dol net is used on the coast of Maharashtra. • It is a combination of bag net and a fixed trap and is used for Bombay duck fishery. • It is a large bag net fixed in the sea by stout wooden poles or by thick ropes anchored with heavy stones. • The net is maintained in a horizontal position facing the tidal flow.
- 68. • It is hauled up during the change of tide and the catch is emptied. • It is again fixed against the changed direction of the tide. • It is operated from 15-20m to greater depths. • The length of the net is about 56m. • The width near the mouth of the net is about 30m and the height is about 18m. • The net gradually tapers towards the other end i.e. the cod end.
- 69. • The total length of the wooden pole is about 32m and about 8m remains below the substratum. • The mesh size of the net near the mouth is 200m and it gradually reduces to 10mm at the cod end.
- 71. Hooks and lines • Hooks and lines are gear where the fish is attracted by a natural or artificial bait (lures) placed on a hook fixed to the end of a line or snood, on which they get caught. • Hooks or metallic points (jigs) are also used to catch fish by ripping them when they pass in its range of movement. • Hook and line units may be used singly or in large numbers.
- 72. • These gears are hauled by hand in small-scale fisheries whilst in large-scale fisheries vessels are usually provided with powered line haulers, automatic jiggers, line reels, line coilers and automatic hook handling and baiting systems. • These gears are suitable for almost any size or type of vessel that can operate in the area being worked. • They can be employed also without boat, directly from the coastline (jetties, rocks, beaches, etc.).
- 73. • The fish are attracted by the natural or artificial bait, hooked, and held by the mouth until they are brought aboard the operating vessel which periodically hauls the gear. • The target species are pelagic, demersal and benthic. • Hooks and lines are generally operated in a very wide range of depths, either in inland and sea waters. With line fishing it is possible to catch fish on rough ground, even in their hiding places between the rocks.
- 75. Pelagic trawls • The target is a wide variety of schooling pelagic species including anchovies, herrings and mackerels, and fish that gather to spawn such as sea bass and cod. • The front net sections are often made of very large meshes or ropes, which herd the fish towards the back of the funnel-shaped net. Pelagic trawls may be towed by one or two (pair trawl) boats.
- 76. • Advantages This method can be highly specific, with little bycatch of other species, when targeting adult schools of one species. • Problems Pelagic trawls, especially large pair trawls, are associated with bycatch of cetaceans, turtles, and other marine mammals in some areas, such as common dolphins in the sea bass pair trawl fishery in the English Channel. Bycatch of juvenile fish of the target species may also be high in some fisheries.
- 78. END OF UNIT IV