Fishing Gear Assignment

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Fishing Gears use for small pelagic and marine fishery field in sri lanka

Transcript of Fishing Gear Assignment

Marine Fishing Gear & Fishing Method(GS/M.Sc./FOOD/3608/08)

B.K.K.K. Jinadasa

[Marine Fishing Gears & Fishing Methods]

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A fishing gear is the tool with which aquatic resources are captured, whereas the fishing method is how the gear is used. Gear also includes harvesting organisms when no particular gear (tool) is involved. Furthermore, the same fishing gear can be used in different ways. Fish capture technology encompasses the process of catching any aquatic animal, using any kind of fishing methods, often operated from a vessel. Use of fishing methods varies, depending on the types of fisheries. The large diversity of target species in capture fisheries and their wide distribution requires a variety of fishing gear and methods for efficient harvest. These technologies have developed around the world according to local traditions and, not least, technological advances in various disciplines. In recent decades major improvements in fiber technology, along with the introduction of other modern materials, have made possible, for example, changes in the design and size of fishing nets. The mechanization of gear handling has vastly expanded the scale on which fishing operations can take place. Improved vessel and gear designs, using computer-aided design methods, have increased the general economics of fishing operations. The development of electronic instruments and fish detection equipment has led to the more rapid location of fish and the lowering of the unit costs of harvesting, particularly as this equipment becomes more widespread. Developments in refrigeration, ice-making and fish processing equipment have contributed to the design of vessels capable of remaining at sea for extended periods. A common way to classify fishing gears and methods is based on the principles of how the fish or other preys are captured and, to a lesser extent, on the gear construction. We can classify the main categories of fishing gear as follows: Towed or Dragged gear i. ii. Trawling Dredging

1. Encircling gear i. Purse seine

[Marine Fishing Gears & Fishing Methods]ii. Beach seine

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1. Statics gear i. ii. iii. iv. Gill nets Trap nets Long line Pots and traps

1. Other mobile gear i. ii. iii. iv. v. vi. Line fishing Net fishing Harpooning Collecting Trolling Lift net

Fishing gears can be classified other ways also, which is; 1. Active fishing gear Fishing gears are move here, i. ii. iii. Herding fish in to fish trawl net, seine net Encircling net Catching by aggregation (FAD) Using repellents - sound, color, visible objective Using attractants Baiting (live or artificial), lightening

[Marine Fishing Gears & Fishing Methods]1. Passive fishing gear Fishing gear is not move here. i. ii. Passively laid net Fixed traps

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Fishing gear can be classified according to the fishing methods for commercially important species 1. Demersal Species (Whitefish such as Cod, Haddock, Whiting, Flatfish, etc.) Bottom Trawling (Single-boat) Bottom Trawling (Pair) Seine Netting Pair Seining Beam Trawling Long lining Set-nets 2. Pelagic Species , Mackerel, Sprat) Purse Seining Mid-water Trawling (Pair) Mid-water Trawling (Single-boat) 3. Shellfish (Nephrops, Shrimps, Scallops, Queens, Lobsters, Crabs, etc.) Bottom Trawling (Single-boat) Scallop Dredging

[Marine Fishing Gears & Fishing Methods]Potting and Creeling 4. Migrating Game Fish (Salmon, Sea trout) Bag-Nets, Stake-Nets Beach-Seining Haaf-Nets

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Trawling: Trawling is the operation of towing a net to catch fish, and the basic requirements for operating the trawl-net are sufficient power to tow the net, a means of holding the mouth of the net open while towing, a system of wires to connect the net and gear to the source of towing power and the ability to cast and haul the net. Vessels provide the necessary towing power, from small inshore boats up to large deep-sea trawlers, with the size of gear scaled to match available horsepower. They may be designed to tow the fishing gear either from the side or from the stern and also provide accommodation for the crew, transportation to and from the fishing grounds and a working platform for fishing operations. Winches installed on deck move and store the trawling wires or warps. Auxiliary winches, power blocks and net drums or used to handle the gear while hauling and shooting. A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are dragged along the bottom of the sea or in mid water at a specified depth. A trawler may also operate two or more trawl nets simultaneously. There are many variants of trawling gear. They vary according to local traditions, bottom conditions, and how large and powerful the trawling boats are. Main trawling types are: 1. Bottom trawling 2. Mid water trawling (pelagic trawling)

[Marine Fishing Gears & Fishing Methods]3. Dredging

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But there are so many types of trawling, Demersal Otter Trawling, Shooting and Hauling Otter Trawl Gear, Twin Rig Trawling, Demersal Pair Trawling, Beam Trawling, Shellfish Trawling, Pelagic Pair Trawling (Mid-water Trawling), Pelagic Single Boat Trawling etc.

Bottom trawling Bottom trawling is trawling (towing a trawl, which is a Bottom trawling targets fish (ground fish) and semi-pelagic species such as cod, squid, shrimp, and rockfish. Bottom trawling can be carried out by one trawler or by two trawlers fishing cooperatively (pair trawling). Bottom trawling has been widely implicated in the opulation collapse of a variety of fish species, locally and worldwide, including orange roughy, barndoor skate, shark, and many others. Today, some countries regulate bottom trawling within their jurisdictions. Mid water (Pelagic) trawling Mid water trawling is trawling, or net fishing, at a depth that is higher in the water column than the bottom of the ocean. It is contrasted with bottom trawling. Mid water trawling is also known as pelagic trawling and bottom trawling as benthic trawling. In mid water trawling, a cone-shaped net can be towed behind a single boat and spread by trawl doors, or it can be towed behind two boats (pair trawling) which act as the spreading device. Mid water trawling catches pelagic fish such as anchovies, shrimp, tuna and mackerel, whereas bottom trawling targets both bottom living fish (ground fish) and semi-pelagic fish such as: cod, squid, halibut and rockfish. Whereas bottom trawling can leave serious incidental damage to the sea bottom in its trail, mid water trawling by contrast is relatively benign. Dredging Dredge consists of a ruggedly constructed triangular steel frame and tooth be bearing bar or sword, behind which a mat of linked fishing net) along the sea floor. both bottom living

[Marine Fishing Gears & Fishing Methods]steel rings is secured. A frame, sides and after end of this in which the catch is retained. Scallops, which usually lie recessed in sand and fine gravel, are raked out by the teeth and

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heavy netting cover or back is laced to mat to form a bag

swept into the bag. Several dredges are shackled to a hollow steel tow bar fitted with chain bridles, one for each dredge. The entire assembly is towed on a single wire warp and larger vessels generally tow two bars, one on each quarter. Ships rigged for beam trawling deploy dredge arrays from outrigger booms in the manner of beam trawls. The number of dredges used varies with towing power, handling capabilities and area, with fourteen (i.e. seven on each side) a fairly typical number, although the largest vessels may deploy more. The target group is mollusks, scallops etc. Impacts Environmental see the environmental impact caused by Bottom trawls; Beam trawls; trawls. The major potential detrimental impact of trawling on species can be the capture and removal from the ecosystem of small sized organisms and non-target species, which frequently are discarded at sea. Such impact can be mitigated by using larger meshes in the cod ends and/or devices in the trawl that reduce capture of small and unwanted organisms. Purse-Seining The seine netting method developed in Denmark. Scottish seining modification. The original procedure as fly dragging except for the use of an anchored marker buoy when hauling, and closing the net and warps and net by winch. A common type of seine is a purse seine, n because along the bottom are a number of rings. A rope passes through all the rings, and when pulled, draws the rings close to one another, preventing the fish from "sounding", or swimming down to escape the net. This operation is similar to a traditional style purse, which has a drawstring. The purse seine is a preferred technique for capturing fish species which school, or aggregate, close to the surface: such as sardines, mackerel, anchovies, herring, certain species of tuna (schooling); and salmon soon before they swim up ("fly dragging") was a later is much the same

[Marine Fishing Gears & Fishing Methods]

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rivers and streams to spawn (aggregation). Boats equipped with purse seines are called purse seiners. Impacts Species; incidental capture of dolphins by tuna purse seiners is regarded as an irresponsible fishing practice. Special techniques have been developed to reduce by catch of dolphins; the Medina panel and "back down" operation, which ensure that encircled dolphins are released alive. The increasingly used practice of encircling floating objects, including man-made FADs increases the capture of small sized and immature aggregating around such devices. Beach seineA seine net is a very long net, with or without a bag in the centre, which set either from the shore or from a boat for surrounding