Fish farming (pisciculture) involves raising selected fish species commercially under scientifically controlled conditions in enclosed water bodies such as ponds, lakes, etc, where they live, feed, breed and are harvested for man’s use.

Common fish species reared commercially include salmon, tilapia, catfish, carp, etc.

Fishery: This is the study of fish and other aquatic animals. Fish live in water bodies (e.g. ponds, lakes, oceans, seas, rivers), respire with the gills and possess fins for swimming. They are cold-blooded animals because their body temperature changes with a change in the environment.

IMPORTANCE OF FISH FARMING

Food: Fish and other aquatic organisms are used mainly as human food. Fish flesh is regarded highly for containing first-class animal proteins, vitamins and many mineral salts and other chemical substances that are needed to keep the human body healthy and strong. The flesh of fish, crabs, prawns and squid is very soft and good to eat. Fish and turtle eggs are also commonly eaten. Fish eggs, which are salted and prepared for eating, are called caviar.
Leather: The skin of cartilaginous fish such as sharks is tough and covered with small, sharp spines. It is sometimes dried and specially treated to produce very special leather called shagreen. Crocodile and turtle skins also make very good leather for handbags, wallets, belts and shoes.
Polishing material: Dried fish skin or shagreen is sometimes used like glass paper for polishing surfaces.
Ornaments: The scales of fish are sometimes used to make artificial pearls which can be worn as beads. Oysters contain pearls, which are polished and worn as jewellery.
Soap and medicine: The oils obtained from fish, whales and turtles are used as food and also for the manufacture of medicines and soap. Cod-liver oil is a very popular item consumed by many people as a food supplement.
Animal feed: Many fish and parts of fish which are not eaten by humans are processed into fish meal and used in the manufacture of livestock feed.
Building: Shells of oysters and periwinkles are sometimes mixed with cement and sand for building houses. The periwinkles make the wall stronger and highly attractive.
Glue and fertiliser: Fish bones are also used for the manufacture of glues and fertilisers.
Income

PRESERVATION OF FISH

This process involves keeping harvested fish long enough to ensure they maintain a very high level of freshness before consumption. Preservation prevents spoilage, injury or destruction, and this keeps the fish in edible condition for a long time. Harvested fish, if not well stored, will spoil and cause great loss to the farmer, hence the need to prolong their shelf life. Preservation can be carried out in any of the following ways:

Salting/Curing: Application of salt in the fish, which prevents the growth of spoilage organisms, should be practised. Well-salted fish can stay a long time without spoiling, provided the fish was originally fresh.
Smoking: This is the drying of fish over fire. This reduces the moisture content and improves the taste and flavour of the fish. It also gives colour to the fish. It is necessary that the fish be constantly reheated and aerated, and kept away from flies to make it fit for consumption.
Canning: This involves the storage of the processed and consumable fish in cans under special conditions for future consumption and sealing the cans so that air cannot pass into them. For example, Geisha, Sardine, etc.
Sun Drying: This involves the drying of fish using the direct heat from the sun, called solar energy. Here, the fish can only be stored for a short time. It is common in Northern Nigeria. It is simple and slow. It is not easily practised in the Southern part because of high humidity.
Freezing/Refrigeration: This is called chilling. This involves the use of cold storage, like deep freezers and refrigerators, to store fish for a long time at very low temperatures, where bacteria become inactive until the fish are needed. Storage can be done as long as possible, provided the system is on.
Conversion to feed meal: Parts of fish (especially parts that are damaged or not good for human consumption) are dried and ground into powder known as fish meal. This is used as an essential ingredients of livestock feeds. Fish meal is useful to farmers in raising livestock.
Roasting: This involves burning fish over naked fire for a short moment.
Icing: This involves placing an ice block over the harvested fish in a container. This method is temporary.
Steam cooking: This involves cooking harvested fish over hot steam.
Irradiation: this involves the treatment of fish non harmful dosage of ionizing radiation this helps to slow down or halt spoilage by retarding enzymatic action and or destroying microbes.

Some of the aim of preserving fish

To retain the quality and quantity of fish.
To increase the shelf life of the food.
To develop different types of fish food.
To maintain all-season supplies.
To avoid spoilage caused by microorganisms.

PROCESSING OF FISH

Processing is the changing of food material fish, from one form to another. It involves the removal of inedible parts and changing the fish from one form into a preservable form. These are examples of things removed during processing: gut, scales, gills, bones, and fins. Byproducts of fish processing include fish meal, fish scale, cod liver oil and fish skin.

EVALUATION

Differentiate between fish processing and preservation.
List things to be removed when processing fish.
List four aims of processing fish.

FISH HARVESTING

Harvesting is the collection of fish from a pond for consumption, preservation or sale.

Methods of Fish Harvesting

Fishing methods involve the use of different techniques or equipment used in harvesting fish.

Netting: This involves the use of nets to catch fish. Examples of nets include gill nets, clap net, trawl net, scoop net, beach seines, drag net, drifting or floating nets, cast nets, etc. Nets are woven to various sizes and thicknesses and are thrown into water to catch fish. Each type is used differently. Nets: These are made from fine cotton or nylon, and the thread is lowered into the water. A small weight made of lead is attached to the edges of the net, which helps it sink to the bottom of the water. When the net is pulled up, it encloses many fish, which are then caught between the holes called the mesh of the net.
Trapping: – This is the setting of traps to catch fish. Gears made from ropes or raffia are woven into various sizes for capturing fish. The traps are set along water courses, and any fish that comes into them is trapped. There are many types of fish traps which can be made either from bamboo, canes, raffia, oil palm or coconut palm fronds or wire and wire mesh.

Hooks and Lines: – This involves the use of hooks tied to strings then set along a water course. The hooks are baited with food to attract the fish.
Use of Ultrasonic: – This is an instrument that makes sound in the water to attract fish. Other means of harvesting, like a net, can later be used to pack them.
Electro fishing: – This is the use of an electric field connected to the water to electrocute the fishes become electrocuted. It can only be used for the total harvesting of fish.
Impaling: This involves the use of spears or harpoons, or any sharp objects (wounding equipment) to attack and catch big fish, e.g. sharks.

Pots and Gourds: Some fishermen who fish in ponds and shallow lakes place clay pots and gourds in the water to catch the fish when fish enter them.
Screen or barriers: Screens made with bamboo, raffia or oil palm fronts are used to enclose portions of shallow water. When fish enter the trap/enclosed areas at high tide, it cannot escape at low tide when the water is reduced, hence they are collected.
Fishing without equipment: Some aquatic animals can be caught without any kind of fishing equipment. They are picked up by hand, having been driven to the mud and plants on which they are attached by the water current. Examples are periwinkles, oysters, and clams.

BASIC LAWS AND REGULATIONS OF FISHERY IN NIGERIA

Fishery regulations are rules and laws governing the exploitation and other practices of fishery resources.

The regulations include the following

Catch quota: This is a form of control in which fisherman is allowed to catch a specific quantity of fish or regulating the number of fishermen by issuing them a permit or license at a specific amount.
Close season: This is a regulation under which fishing is not permitted to take place for a given period of time. This helps in making the younger fish to grow and mature.
Mesh size regulation: This involves the use of a standard size net or mesh so that only the mature fish are caught, thus leaving the younger ones to grow to adulthood before harvesting.
Population control: This involves the process of cannibalism, where fish types like catfish are made to eat other fish like Tilapia or early harvesting to prevent overpopulation.
Regular stocking: This is the introduction of compatible species of fish to increase the population of fish in the water.
Prevention of vessels: No vessels (except canoes) are allowed to fish within the first two (2) nautical miles of the Nigerian Continental Shelf.
Prohibitive use of explosives: The use of explosives is prohibited as this kills young as well as old fish.
Ban on the use of poisonous chemicals: The use of poisonous chemicals like Gammalin 20 is prohibited, as it kills both young and old fish.
Landing tax: Landing tax is used such that the total catch and sizes of fish are taxed at the site of landing.
Allocation of fishing areas: Fishing areas are allocated to individual fishermen to prevent interference with larger fishing areas.

GENERAL EVALUATION

What is a fishery?
What is fish farming?
Differentiate between cold-blooded and warm-blooded animals.
Mention eight important aspects of fish farming.
Describe four methods of harvesting.
Differentiate between fish processing and preservation.
List four aims of processing fish.
List eight fishery regulations.

WEEKEND ASSIGNMENT

Fish eggs, which are salted and prepared for eating, are called A) Shagreen, B) Caviar
C) Canivar D) Smoked egg.
Glues and fertilisers are produced by using _____ A) shells of oysters, B) Fish bones
C) Scales of fish D) Cod-liver oil.
___ contain pearls which are polished and worn as jewellery.A) Oysters B) Crocodile
C) Turtle D) Lobsters.
The skin of sharks is dried and specially treated to produce very special leather called
A) Shannon B) Shagreen C) Shagrey D) Shy green.
Processing entails the removal of ___ parts of the fish. A) edible B) inedible C) bone
D) fish
Preservation prevents the following except ____A)spoilage B)injury C)processing D) loss.
The drying of fish over fire is known as ____ A)smoking, B)salting, C) freezing,g D) roasting
Which of these is the process of putting in tins with special oils and paste? A) smoking
B) freezing, C) chilling,g D) icing.
Examples of water habitats that can be caught without the use of equipment are ____
A) periwinkle, B) turtle, C) oyster D) clam.
A ___ is anything that attracts the fish into a trap set for the fish. A) bat B) bait C) food
D) sweet.

THEORY

Describe four methods of fish harvesting
State four ways of preserving harvested fish
Discuss briefly four fishery regulations (WASSCE 1993 question 8, 2009 question 8d,2017 question 6c, 2008 question 8d, 2014 question 5e)
Give the scientific names of three fish species commonly stocked in a pond (WASSCE 2009 question 7c)
Give three reasons why fish farming is important (WASSCE 2013 question 7a)
Enumerate two reasons why the use of chemicals is discouraged in fish harvesting (NECO 2018 question 8e)

FISH FARMING