FISHERIES1. Identify the various types of fish and other organisms. 2. State the uses offish and fish products. 3. Identify the various fishing equipment and describe the methods of fishing. 4. Outline the various methods of preserving fish.
Fishes are aquatic animals. That is, they live in water such as ponds, lakes, rivers, oceans and seas. They possess which enable them to swim in water and gills with which they are able to obtain oxygen from water. Fishes are regarded as "cold blooded animals". This is the temperature of their body changes with the temperature of their surrounding. The rearing of fishes in ponds or other bodies of water is to as fish farming.
Fishery is that branch of agriculture which] with the production of fishes and other aquatic animals. Figure 3.9,1: A Typical Fish
9.1 Importance of fish farming Fish farning is important to man in the following ways 1. It is a source offish for food. Fish is a good source of protein in human diets.
2. It makes good use of the land that would have otherwise .Miilable for arable farming.
3. It serves as a source of employment for fish farmers, 4. It reduces the pressure of fishing in natural waters e.g. rivers, and lakes. 5. It serves as a source of income to fish farmers and traders. 6. Fish farming can lead to the improvement of natural fish stocks Likes, rivers etc. since the young ones can be raised in It heries and used for restocking, trips in the production of sports fish, ii dsh can be produced for use in industrial fishing.
9.2 Classification of Fishes Fishes can be classified according to their: (a) Habitat (b) Morphology 1. According to Habitat Habitat refers to the living environment of an organism. Fishes water. There are three kinds of water habitat HI which fishes are fresh water, salt water and estuarine habitats. (a) Fresh water habitat: This refers to water which contains no salt. Such water is found in springs, rivers, ponds, lakes, etc. Fishes that are found in fresh water habitat are called fresh water fishes. Examples include electric fish, moon fish, cat fish as clarias and heterobranchus longifilis, gymnarchus niloticus, and tilapia spp. DIAGRAM Figure 3.9.2: Tilapia galilaeus
(St. Peter's Fish). (b) Salt water or marine habitat: this refers to water body that has salt taste. Its salt content is about 3% per volume of water. Such water can be found in seas and ocean. Fishes found in salt water or marine habitat are called salt water or marin fishes. Examples mclude shark, mackerels, herring, sardine, cod (stock fish) (c) Estuarine habitat: this refers to water found in estuarine where rivers flow into the seas or ocean. Examples is the Nioiger Delta are of Nigeria. That salt content of this habitat is in between the content of fresh water habitat and marine habitat. Fishes may not permanently line in this kind of habitat as some do migrate from fresh water or from salt water into the estuaries and go back thereafter. An example of such fishes is mudfish. According to morphology This has to do with the form or structure of the fish. There are two categories in this class (a) Nature of bone: Fishes can be classified according to the nature of bobe (i) Bony fishes; These posses bony skeletons or hard bones. Examples include Tilapia, mudfish, catfish. (ii) Cartilaginous fishiss: These possess solid bones or what is called cartilage (Biscuit bone). Examples include shark; dogfish.
(b) Nature of body covering: Based on this, fishes can be classified into: (i) Scaly fshes: These have their body, parts of their head and tail covered by scales which overlap, pointing towards the tail end of the fish. Example is the tilapia galilaeus (Seefigure 3.9.2). (ii) Non-scaly fishes- These have no scales. They have smoothshiny skins. Examples are dogfish, mudfish, mackerels. 9.3 Other Aquatic Food Organisms There are many other organisms that live in water, apart from the, which are used as food by man. These organisms include: 1. Crustaceans such as prawns, shrimps, cray-fish, lobsters, crabs. DIAGRAM Figure 3.9.6: Crab. 2. Molluscs such as river snail, periwinkle, oysteter. Thcsf usually covered with shell and these shells servve some useful purposes to man, in addition to their meat. DIAGRAM Figure 3.9.7: River Snail. 3. Reptiles such as river snake, turtles, etc. 4. Mammals such as Hippotamus 9.4 Common types of fish Some common types of fish include Common name Scientific name Tilapia Sarotherodo niloticus Cat fish Haters branchus spp Snake head fish Channa obscura Trunk fish Gymnarchus niloticus Milk fish Chanos chanos Moon fish Citharinus spp Mullet Mugil spp Carp Cyprilius carpia Mud fish Clarias spp African bony tongue Heterotis niloticus 9.5 Use of Fish and Fish Products 1. Food Fish is eaten by man as part of his diet and is a good source of protein. 2. Source ofincome Fishes are sold for money and this provides a major source of income to fish farmers ad fish traders 3. Fish watching Man derive great pleasure from watching fish in private and public ponds, television screesn and movies.
4. Scientific study Fish are used for scientific experiments and researches t to increase knowledge
5. Recreation Sport fishing as a recreation man has played important role in the social lives of people who are engage in it. In other words, it has contributed to their happiness. 6. Improvement of human health Some species of tilapia and top minnows have been used to control malaria in the tropies since they prey in mosquitoes.
7, By-products Some by-products offish are useful to man. Examples include:
(a) Fish meal: This is obtained by grinding dried parts of fish. It is in animal protein source, especially in poultry feeds. (b) Fish oil: Oil can be extracted from fish and used by man. There are two kinds of fish oil. The one that is Extracted from the fishes themselves which is used in making paints, enamels, vanishes, candles, and soap; and the one which is extracted from fish liver, usually from the cod fish (stock fish) known as cod liver oil. This contains a lot of vitamins and is used as medicine, especially for babies.
(c) Fish manure: The discarded parts of fish as well as those fishes that have gone bad are heaped to decompose and are used as manure for growing crops. (d) Fish skins: The skins from fishes especially sharks, are used as leather for bags, shoes and other leather works. 9.6 Fishing, Processing and Preservation of Fish 1. Methods of Fishing There are different methods used to catch fish from the water. These methods include:
(a) Use of nets: Nets are made of nylon and are used for fishing both in large and small bodies of water. Net fishing is very efficient because many fishes can be caught at a time with a net. T
here are different forms of net used for fishing.
These are: (i) The cast or throw nets (ii) The gill nets (iii) The lift nets (iv) The hand net or scoop net. (b) Use of hooks: A hook is made of metal rod which is curved at the tip. Fishing hooks are of two kinds: (i) The pole and line hook: This consists of a hook to which a twine is tied, which 'in turn, is tied to a long pole or stick. A weight or float (could be a small stone or metal nut) is tied to the rope to enable the hook go down the water. Fish is attracted to the hook by a bait (e.g. earth worm) attached to it. When a fish attempts to eat the bait, ils mouth is hu to the hook and the fisher quickly throws oul the honk the water to remove the fish. The method is time and labour consuming. Only one fish can be caught with this method it a time.
Figure 3.9.11: A Pole and Line Hook. (ii) Long line hook: This consists of several hooks tied to a long line. The whole line is then tied across the course of the stream. Baits are attached to each hook. This can be left for a long time, while checking to see if any of the hooks has caught a fish as well as to replace the baits. Many fishes can be caught at a time with this method. DIAGRAM Figure 3.9.12: Long Line Hook. (c) Use of baskets: Baskets are mainly used in fish pond. They are tlhjp.f.'.i'il through the water to catch the fishes in it. Baskets are U'.i-d lor periodic harvesting by selecting only large fishes from tin- entire catch and throwing back the under-sized ones into the \\ iilcr. Many fishes can be caught with baskets at a time. (d) Use of fish traps: These are woven materials usually with fanes, rid, ropes er wires. They are designed in different shapes and sizes. When placed in water, fishes are attracted into them by baits placed inside. When the fishes enter, they cannot come out. Hand net Cast net Drag net Fishing trap Figure 3.9.13: Fishing nets and trap. (e) Use of spear or harpoon: This is used for large fishes like the shark. It is not however a very common method these days. (f) Drainage: This is common in ponds or shallow streams which can be blocked to drain away water. The fishes are then easily. It is used for total harvesting in ponds. (g) Useof fishing trawlers, boats or canoes: These are means of transportation in water. They enable the fishermen to go into the water from which they can cast nets or set out hooks to catch fishes 2. Bad Fishing Methods The following are considered bad "methods of fishing und should not be used: 1. Use of poisons, or chemicals such as gamrhalin 20. 2. Use of explosives. 3. Electric stunning, that is, passing electric current into I lie \v»t(r to stun or electrocute the fishes before they are picked. 3. Processing and Preservation of Fishes The following are ways of processing and preserving fishes: (a) Smoking: Fishes are smoked by putting them over a fire and covering them on top. (b) Drying: This can be done by using fire or sun. Drying helps to reduce the water content in the fish and it can preserve the fish for a very long time. (c) Canning: Fishes are processed and canned for export. This method .provides a long lasting means of fish preservation. Examples of canned fishes are sardine, Geisha, Queen of the Coast. (d) Salting: Fish can be preserved by.rubbing salt on the body. It keeps the fish for a short time unless it is followed in drying. (e) Chilling or freezing: Fish can be preserved in fridges, deep freezers and cold rooms. This method helps to keep fishes for a long time provided there is constant power supply. (f) Icing: This is done by puttuig blocks of ice round fishes usually in cooters. The fishes can be transported with this method and can last so long as the
iceTemains. other methods include steammg, cooking, frying and roasting. 9.7 Factor to consider sitting a fish pond The
following .factors should be taken into consideration before sitting a fish pond in any environment.
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