Fishing Gears and Crafts, and Their Maintenance
The main wealth of fishermen and women in developing countries is in their fishing gears which are subject to rapid depreciation and lose. They rely on less than optimal fishing vessels, methods and gear which limit their catch, especially when they are competing with the industrial sector. Their machineries are expensive, difficult to repair, and not fuel efficient. Fishing practices tend to be labour intensive with minimal mechanical assistance. The total investment in fishing equipment is generally quite low, and the artisanal fisherman is adept at minimum input management. Fishing productivity is consequently variable and low. They face a series of difficulties that contribute to their marginal standard of living. Gear preservations are important in prolonging their lifespan and lessening the expenses and other hardship that they could encounter. A well maintain fishing gear is an asset to them guaranteeing provision of fish to their household consumption and market. The subject of fishing gear can conveniently be divided under the following; Traditional methods, Conventional methods, Unconventional methods, and Illegal methods.
Hooks and Lines
A hook is a bent steel rod flattened or ringed at the straight end of the shank and with a barb point at the inner side of the extremity of the bend. Line fishing is a traditional way of catching fish in Nigeria, especially in the riverine areas and coastal lagoons. The principle used in this method is to offer the fish bait fixed to a hook at the end of a line or rope. The fish while trying to bite the baits swallows the hook and get caught. Halts may be animals such as earthworms, insects or smaller fish, and plant roots materials. Fish can also be caught by gelling, hooked on scale, gills fins and other external appendage without even using a hail. Hooks and lines unit may be used singly (Figure 1) or in large numbers - long line (Figure 2).
Hand lines are used with or without a pole or a rod from canoes, beaches, jetties and bridges in rivers, lagoons and estuaries. This fish capture method is used mostly by the children of fisher folks. The most common baits used are earthworms, pieces of fish and soap.
A set long line consists of a main line to which few of numerous short secondary lines (snoods), each terminating in a hook, are tied. The line may be placed on or near the bottom none baited or baited. A set long line is used in coastal waters, rivers, lakes, creeks and estuaries. Drifting long lines are placed near the water surface or at a certain depth by means of positive buoyancy, using good well-spaced floats. Drifting long lines are normally longer than bottom long lines and their snoods are more widely spaced. It is used mainly at night in 3-10 metres depth of water throughout the year and catches mostly predatory fish. Drifting long lines are also used in the throughout the year and catches mostly predatory fish.
Drifting hook and line set in the sea.
Care for Fishing Hook and Lines
- Fishing hooks should be arranged in such a way as to give gap in spacing to avoid entanglement. Entangled hooks waste the fisherman's energy and time in rearranging.
- Hooks should also be mounted with correct mounting twine to avoid loss in water. ●While bailing the hooks, care should be taken to avoid hand injuries.
- Hooks should not be set when water tide is high to avoid loss.
- When hooks are used in "strong" water i.e. with corroding power, they should be lifted every 24-48 hrs depending on the fish concentration.
- Hooks should not be set in areas where seining is being practiced to avoid damages to nets.
- When set in short or long line, hooks should be removed from water after every 3 5 days for cleaning and replacing of missing ones.
- In order to maximize hook efficiency, 500-1000 hooks can be set in a long line.
- After fishing when hooks are not in use they should be collected and carefully wrapped in fine leather.
- Always check the line for areas of abrasion that will cause a weakness.
- After every fishing trip, or after playing out a nice fish, cut off approximately ten feet of line if you notice weakness of the along the line (may be due to struggles with fish caught).
- Don t keep your equipment in direct sunlight but rather in a dry, shaded area.
- Remember, proper maintenance, balance, storage and handling are imperative in taking care of the equipment that takes care of you.
Traps
Traps are traditional devices which can retain fish on entry or make their exit very difficult. They are made in various forms and shapes with different types of materials such as wood, metals, fronds, netting etc.
Their design and operation match the specific conditions and behavior of fish in a given area. Hence the importance of local knowledge in design and placement cannot be overemphasized. Corrosion is always a serious problem with metal traps. One solution is to use marine mesh, which combines the strength of steel wire with the durability of plastic. The steel or galvanized wire is coated with polyvinyl chloride. Zinc or aluminum anodes can also be attached to metal traps to create a galvanic couple with the iron and double or triple the life of the wire netting. Different traps are used in the Nigerian artisanal fisheries. These include:
1. Pots trap
These are fabricated to catch fish and shellfish and are in the form of local pots (for storing potable water), baskets and cages. They are made up of clay, netting (both wire and fibres), wood and metal rods. Over 90% of them are provided with non-return valves through which the fish enter. They are set at the bottom singly or in rows with or without baits.
2. Basket trap
This is the commonest trap used in rivers, lagoons, lakes and estuaries. It is conical in shape and made of palm frond cane strips (Figure 3). The trap usually has one or two non-return valves with openings ranging between 3.0cm 1.0m in diameter. The length of the trap also varies from 30.0cm 3.5m. It is used in catching both shellfish and finfish mostly by women and children. The wire basket trap is a variant of the basket trap used in the upper Cross River are at Ikot Opara for catching tilapia. It is made of wire and baited with abrasive leaves.
3. Shrimp Basket Trap
This is a conical basket filter trap called Kokobi (Ijaw) and Ekobi (Itsekiri). It is used by fisher folks in riverine estuaries of Delta, Rivers and Akwa Ibom States. The body of the trap is 1.00-1.60 metres in length, and is made of raffia palm ribs, canes or aerial roots of mangrove trees which are spaced 2.00 - 3.55mm apart. The trap has a circular mouth, 0.4 - 0.8 metres in diameter, which is strengthened with the same material as the body and which narrows to a pointed closed apex. There is also a U-shaped cane loop which is tied at right angles to the mouth. The improved form of this trap fabricated with synthetic nettings and anchors is known as the stow net.
4. Ita Trap
This is a very big conical trap used in estuaries and rivers of Lagos, Ogun, Delta, and Rivers States. In Lagos State, it is known as Ighana (Yoruba). The trap is made of sliced cane or bamboo matting and is 8 - 36 metres in length. It has a funnel-shaped mouth, 2-5 metres in diameter which gradually tapers to a smaller opening, 0.46 -0.91 metres in diameter. The mouth has a strongly constructed rim, while canes are radially and vertically arranged in the main body.
5. Gura Traps
Gura (Hausa) traps are effectively used in freshwater rivers and lakes. The traps are traditionally made of fine strips of liana or vine which are bound together into twines. They are large, varying from 1-3 metres in length with only one non-return valve which is often placed in the centre
6. Bamboo Trap
This trap is used in small brackish water bodies, creeks and rivers in Ondo, Ogun, Delta and Lagos States. It is set in very shallow waters throughout the year. In Lagos State, it involves the use of a hollow bamboo trunk, 40-60m in length and 5-8cm in diameter. The bamboo trap is struck vertically to the lagoon bottom and a stick of about 45-70cm in length is stuck into the hole of the bamboo.
7. Fences, Barriers, Weirs and Shelters
These are made of various materials such as weeds, palm fronds, tree branches as well as canes and are staked in rivers, estuaries, creeks or lagoons. The fences provide shelters for fish and this facilitates their congregation and capture, especially when they are left undisturbed for between 1-3 months. They are variously called Awan (Yoruba) or Baban Chamba (Hausa).
Figure 6: Fish Fence/Barrier
Care of Traps
• Natural fibres and canes are liable to rotting therefore traps should not be left for too long, in the water. When removed from the water they should be kept away from rodents.
• When traps are set, they should be against the current in shallow waters or river bank with support provided to prevent them from being washed away.
• Traps should be avoided in rivers with too much effluents or solid wastes to avoid accelerated rotting.
• For durability iron frames are preferred in constructing traps.
• When traps have been removed from water and dried, they should be washed cleaned before storing.
Nets
A net is a piece of webbing where cotton, silk flax, flax hem, nylon twines are use to make the meshes of definite sizes. These may be simple interlacing or knots at the point of intersections between twines. As per the requirement, the webbed pieces are joined together to give different shapes and dimensions to the type of net. For effective functioning the nets are provided with some important accessories;
Ropes and cables: Made of cotton, hemp, flex, nylon, or steel and generally used for spreading, hanging, laying, hauling of the nets.
Floats: Usually a log of wood, empty water proof cans and sponge plastic, plastic balls, cork, dried gourd etc. used to keep a section of the net floating.
Anchors: Made up of cast iron, used as hold fast for huge-sized gears during operation.
Sinkers: In form of stone, concrete, lead pieces, cast iron, bivalve mollusk shells, etc. attached or tied to that end of the net which remains toward the bottom of water body. These keep that section of the net downwards.
Pulleys and Reeling Device: Steel made devices used to operate ropes or cable ends fixed a shore.
Swivel: The steel devices used to allow rotation of certain section of robe or cable.
Stakes: Different-sized bamboo rods or stick used for fixing up certain types of nets or making barrel-shaped or basket-shaped traps.
Nets are of different designs and patterns but all have natural or synthetic fibres as the raw materials in constructions. Determination of life span of nets depends in the kind of fibre used, the temperature of the water and duration of application of the net in. water.
Vegetable (natural) fibres rot faster than synthetic fibre net. When water temperature is high, bacteria are more active in water. Nets last longer in cold than hot season and decay faster in tropical than temperate regions. Running waters have greater decaying power than stagnant water because of different types of effluents and solid wastes carried in water bodies that are fertile with organic substances e.g. lime and phosphorus. Nets get destroyed faster in such water bodies even though even though they may have higher yield of fish. Nets last longer in clear water.
Types of Nets
Netting operation can be classified into two:
i. Active Netting
Some nets are actively moved taking the help of proper craft or manpower. In these operations the floats and sinkers are so adjusted as to keep the two ends of the net stretched apart during the entire operation. Types are: drag net, scoop nets, movable traps, angling etc.
ii. Passive Netting
No movements of the net are required altogether in such type of netting net, or suspended at intermediate depths. With the help of drop-lines from larger buoys at the surface or suspended near the surface by its own float-line, but the net is attached by means of rope to larger sinkers at the bottom, e.g. gill nets and drift nets, trammel nets, screens, fixed traps.etc.
Types of nets common in the Nigerian artisanal fisheries include the following:
1. Surrounding nets
These nets catch fish by surrounding them both from the sides and from underneath, thus preventing them from escaping by diving (Figure 7).
Figure 7: Surrounding Net.
2. Seine nets
These are long surrounding nets usually set from canoes. They are used to surround schools of fish sighted near the shore or to sweep an area of the seabed. Those operated from the shore are called beach seine. The net may be with or without a bag at the centre and it is usually operated with two ropes fixed to its ends. The ropes assist in herding the fish and are also used from hauling the net.
3. Lift net
This is lifted, raised or hauled upward from a submerged position to catch fish/crab lying on or above the net and the water is strained in the process (Figure 8). The net is generally used in lakes, lagoons, creeks, estuaries and rivers.
Figure 8: Operating a Lift Net
3. Gill nets and entangling nets
The curtain of netting is designed according to the required ballasting and buoyancy to fish on the surface, mid water or on the bottom, and gill, wedge, snag or entangle the fish in the meshes of the net.
Figure 9: Fish trapped by Gill Net
5. Falling gear
These are operated in shallow waters. They are thrown from shore or from a canoe to cover an area of water surface. They catch fish by cover an area of water surface. They catch fish by falling and closing them. Example of these falling gears are the cast nets, which are conical falling nets with lead weight attached at regular intervals along the perimeter of the cone (Figure 10).
Figure 10: Operating a Cast Net
Care of Nets
• Fishing nets left for a long duration in water is naturally more liable to rotting, than when removed intermittently when set especially on water bottom where the contact zone between the putrid mud and the water has strongest rotting power, nets easily rot away.
• Nets should be properly constructed to avoid to loosening, and suitable floats and weight attached when set.
• When operating, rough fishing grounds with free slumps should be avoided lo prevent entanglement and tearing.
• Nets should also not be set on navigational routes. Most fishermen in the Nigerian section of Lake Chad use sign posts in areas where nets are set on navigational routes to prevent destruction.
• When nets are removed from water all fish catches must be emptied, and the nets must not lie stored immediately but washed and spread out in the sun to dry.
• After drying, nets should not be kept near fire as natural and synthetic fibres are flammable.
• When nets are dried, coal tar, wood tar either alone or combined with petroleum, benzene etc. can be used to preserve the net. Chemicals like potassium bi-chromate, copper sulphate etc. can be diluted with water or kerosene and nets dip in the solution, then removed and dried. Most fishermen in artisanal fisheries use natural preservatives like some extracts from leaves and harks of trees to store nets (especially natural fibre nets).
• Natural fibres nets are best preserved with the hot extracts while synthetic fibres are best stored with cold solution.
• Nets materials are expensive therefore fishermen should take adequate care of their nets. They are also more efficient than hooks and traps in total fish catches and by implication economic returns to fishermen.
• The first step in repairing a net is cleaning most of the debris from it and stretching it out so that the damaged areas can be easily accessed. This can most easily accomplished by tying a robe between two trees or other stationary objects.
Bad Fishing Practices to Avoid
• Use of poisons and locally-made hand grenades: This is generally prohibited throughout the country, but the small-scale fisher folks still use toxic plant poisons, chemicals and locally made hand grenades in Nigerian waters either to kill, shock or daze the fish.
• Use of chemical for fishing: This involves the use of synthetic chemicals (in liquid forms), such as Adrex 40, Gamalin 20 as well as Didimacs 25 and toxic plants, in inland waters. The synthetic chemicals which are usually in liquid forms are simply poured on the water surface of small ponds, rivers and creeks to narcotize and kill fish.
• Use of locally-made dynamites and hand grenades: These are used along fresh water river banks and under disused coastal oil platforms which act as artificial fish aggregation device. When the explosives are thrown, explosion occurs killing and stunning all the in the area. The dead and dazed fish are then picked up with hands and scoop nets.
• Use of undersized mesh nets: This has the potentials of wiping out young fish population in a water body.
Preventing Fish Deterioration and Spoilage
In the tropics wet fish is highly perishable because of the harsh climatic environment. As soon as fish dies it is subject to bacteria and autolytic spoilage. In artisanal fisheries the following are responsible for deterioration and spoilage:
i. Time lag between fishing grounds, landing sites and processing centres
ii. Rough handling of catches on board, landing and at processing sites
iii. High temperature and humidity
iv. Shortcoming of traditional processing methods/ ovens.
v. Menace of insects.
Wet Fish Spoilage
Four major sources of spoilage are identified in wet fish.
i. Bacteria Spoilage. Bacteria in skin gills, intestine are activated after death. Examples of such bacteria are- Bacillus spp, Pseudomonas spp, penicillum spp, Escherichia coli and Aspergillus spp. Damaged skin lead to softening of muscles, slime production and offensive odour.
ii. Autolytic (Enzymatic) spoilage
Autolytic spoilage is caused by continuation of normal enzymatic digestive process after death. Fish gut is a net source of enzymes that allow living fish to digest food. After death, enzymes digest fish stomach and eventually fish skin. Bacterial and enzymatic spoilages occur simultaneously in fish.
iii. Poor handling techniques
Fish flesh is delicate and fragile. It should be carefully handled. Sources of contamination are rough handling, dirty platforms, and unhygienic equipment and dirty environment.
iv. Delays in distribution and marketing
Once fish is out of water, it demands immediate refrigeration so as to maintain the fresh quality of the flesh. Delay in product evacuation encourages the onset of deterioration and eventual spoilage.
Cured fish spoilage
Cured fish are less perishable than wet fish. Major causes of spoilage in cured fish are:
i. Microbial spoilage. This occurs in improperly smoked fish leading to mouldy fungus
ii. Insect infestation. Common insects are blowflies (Diptera spp), Dermestes maculatus, Necrobia rufipe, termites and ants.
iii. Fragmentation. This is mainly caused by rough handling after smoking or enroute to market centers.
Challenges Facing Fishing and Fisheries Production in Nigeria
Post-harvest losses are rampart in artisanal fisheries due to several limitations placed on the system. Fish deterioration set in transportation from fishing ground to landing sites; at processing sites due to the low capacities and inefficiency of most smoking ovens; at processing sites due the unkempt environment that promote insect pest infestations; at transportation to market sites due to delay in evacuation of smoked fish, bad road network and short shelf life of the products. All these combined caused an estimated post harvest losses of between 40-60% in a country that only met about 50% of domestic fish protein requirements. Interventions in the artisanal system would reduce the product losses. Nigeria went into fish farming as a result of decrease in supply from ocean fishes due to over fishing, consumer population increase, habitats destruction and pollution.