Fishery: Definition, Classification & Uses Of Fish And Fish Products,Methods Of Fishing And Risk Factors In Water Management & Fish Farming (Agriculture)

Fish Farming is a form of aquaculture practice. Fishery or Fish farming aims at utilizing inland water and ponds for breeding species of fish, their management and control and tapping of fish resource to produce food. The practice includes raising, harvesting, processing, and marketing of fidh and fish products.

Currently in West Africa, more farmers are beginning to recognize the immense commercial value of fish farming and are venturing into it. The need for this arose because the supply of fish via natural water bodies does not meet the demand of man, hence, the practice aims at supplementing the short_fall in natural supply.

Classes Of Fish

Fish can be classified based on habitat and morphology.

A. Classification According To Habitat: Classification here is based on fresh water and marine (salt) water fishes place of abode…

i. Fresh Water Fishes: They are fishes that live in water bodies free of salt, like, rivers, streams, springs, ponds and lakes. Examples of such fishes are, catfish, carp, perch, tilapia, mudfish, etc.

ii. Salt Water (Brackish or Marine Water) Fishes: These are found naturally in salt-containing water bodies, such as, seas and oceans, Examples of such fishes include, salmon, eels, sharks, skates, rays, etc.

B. Classification According To Morpology: This classification is based on their body structure.

i. Bony fishes: These have back-bones (vertical column). This is an internal endo-skeleton, made of hard bones. They are mostly fresh-water fishes, e.g, catfish, perch, tilapia, salmon, carp, mudfish, ceoaker, etc.

ii. Cartilaginous Fishes: These have skeleton of cartilage (soft bones) which is external (exoskeleton). They ate mainly salt water fishes. Examples include, sharks, dolpins, dog fish, skates, rays, etc.

C. Other Types Of Aquatic Animals Other Than Fish: Apart from fishes, other aquatic organisms exist that are also used as food. Examples include, various grqoups of athropods known as shell fishes or sea foods. They include, whales, hippopotamus, etc.

Uses Of Fish And Fish Products

i. Sources of Food: Fish and fish products are very important sources of rich animal protein for man. They are alsio ich in vitamins and minerals, and therefore highly nutritious.

ii. Source of Animals Feed: Fish meals are important fish by-products which supply the protein requirement of farm animals.

iii. Source of Revenue: Fish Farming is a good revenue earner as the return on investment is very high.

iv. Employment: It offers gainful employment opportunities to people, and a lot of investment is very high.

v. Medical values: Some fish by-products have rich medicinal values. Cod liver oil for instance, can be used intreating heart and pulmonary related ailments. It makes the heart function well.

vi. Raw materials: Fish by products like the fish guano can be used in producing fertilizers. Shells of sea foods like oyster, periwinkles, etc, can be used in producing scrubbing materials for cooking utensils. They can also be used in producing local jewelries.

vii. Sports/Leisure: Fishes raised in aquariums are pleasurable and have aesthetic values. Fishing may be a form of activity, game or leisure.

viii. It ensures effective utilization of land area, considered not suitable for other agricultural purposes like arable farming.

ix. The shells of oyester or periwinkle can be used with sand and cement for building construction(s).

Methods of Fishing

The method of fishing can be referred to as cropping.

This can be total, partial, or selective, using nets, traps, baskets, fishing boats, drainage, spear, happoon, etc. The choice of any method would depend to a great extent on the types of aquatic animals involved, area, expertise of the individual, available tool/equipment, etc. Examples of fishing methods are;

i. Use Of Nets: The nets should have the right mesh sizes for harvesting. This is advantageous because the use of net ensures catching of many fishes at a time. They should have weight attached to them, to enable them sink to the bottom of the water during fish harvesting. The different forms of nets are the cast-and throw nets, lift nets, siene nets, gill nets, etc.

ii. Hook/Rod And Line: The materials involved here are the hook, rod, line and sinker which enable the hook go below the water, with a bait attached to it. The bait attracts the fish which gets hooked on trying to swallow it. This is also called luring method.

iii. Canoe/Trawler: Fishing canoe or trawler (ship) s required in the case of catching fishes in seas, oceans, rivers, etc. The nets thrown into the river or sea are dragged into the canoe, and the fishes caught are removed.

iv. Fish Traps: There are different types of traps which may be made from bamboo, cane, raffia wire mesh etc. Some fishermen use this method effectively. This method is also known as entrapment.

v. Fishing Baskets, Pots, Gourds: These are different sizes or shapes. They can be used in the earthen and or the concrete ponds for scooping. Fishes not very matured are put back into the water when caught.

vi. Impaling or striking involves the use of spear or hapoon to strike the fish which is then collected.

Risk Factors In Water And Fish Farming

Good management of both fish and water is of utmost importance especially after stocking. Certain conditions or activities may constitute risk factors in water management and fish farming. They are:

i. Polluting Water With Chemicals And Industrial Effluents: Unpolluted water must be guaranteed in fish farming for result to be achieved. Chemicals and Industrial effluents constitute pollutants in water, with negative consequences to fish farming and may harm the fish species. This is as a result of reduced level of dissolved oxygen content in the water and increased temperature range as well as high acidity level.

ii. Use Of Chemicals For Catching Fish: This is capable of introducing poison into the water, which endangers human life when such fishes are consumed. Didimac 25 and gammalin 20 are few examples of such chemicals. They kill the fishes which then float, and are collected for immediate consumption, preservation or disposal by marketing.

iii. Use Of Explosives: They may be detonated under water, killing some fishes which then float on top of water, and are collected. Dynamite is a typical example of such an explosive.