Aquaculture and Its Type for Competitive exam

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Aquaculture

Aquaculture is the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants. Farming implies some sort of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated.

Types of Aquaculture:

Based on type of water: Based on the type of water, aquaculture in three type – fresh water aquaculture where the culture take place in fresh water, bodies ,brackish, water aquaculture where the culture takes place in brackish water and mariculture where culture takes place in sea water.

Different systems of aquaculture:

On the basis of salinity

Freshwater farming

Brackishwater farming

Marinewater farming

On the basis of intensity

Extensive fish farming system

Semi-intensive fish farming system

Intensive fish farming system

On the basis of fish species

Monoculture

Polyculture

On the basis of enclosure

Pond culture

Cage culture

Pen culture

Race-way culture

On the basis of integration

 Agriculture cum fish farming

Animal husbandry cum fish farming

1. On the basis of salinity

Freshwater Farming/ aquaculture:

Farming of aquatic animals and plants in zero saline water, mostly fresh water farming is inland based. Catla, Rohu, Mrigal, Silver carp, Grass carp, Common carp and Fresh water prawn are mainly farmed in fresh water.
Brakishwater aquaculture is a mixture of seawater and freshwater with a salinity less than 30ppt. All estuaries, backwaters, creeks and mangrove waterways are brakish in nature. Over 25 species of commercially important fishes, shrimps, crabs and mollusks offer a wide scope for farming in brakishwater.

Marinewater farming/ Mariculture:

Farming of aquatic animals and plants in sea water is commonly known as marinewater farming or mariculture. In mariculture rearing of commercially important fishes and shell fishes are done in open sea by installing cages.

2. On the basis of intensity of inputs and stocking density:

Extensive fish farming system:

Extensive fish farming system is the least managed form of fish farming, in which little care is taken. This system involves large ponds measuring 1 to 5 ha in area with stocking density limited to only less than 5000

fishes/ha. No supplemental feeding or fertilization is provided. Fish depends only on natural foods. Yield is poor (500 to 2 ton/ha) and survival is low. The labour and investment costs are low and this system results in minimum income.

Semi-intensive fish culture system is more prevalent and involves rather small ponds (0.5 to 1 hectare in area) with higher stocking density (10000 to 15000 fish/ha). In this system care is taken to develop natural foods by fertilization with/without supplemental feeding. However, major food source is natural food. Yield is moderate (3 to 10 ton/ha) and survival is high.

Intensive fish farming system is the well-managed form of fish farming, in which all attempts are made to achieve maximum production of fish from a minimum quantity of water. This system involves small ponds/tanks/raceways with very high stocking density (10-50 fish/m3 of water). Fish are fed completely formulated feed. Good management is undertaken to control water quality by use of aerators and nutrition by use of highly nutritious feed. The yield obtained ranges from 15 to 100 ton/ha or more. Although the cost of investment is high, the return from the yield of fish exceeds to ensure profit.

3. On the basis of number of species stocked for farming:

Monoculture:

Monoculture is a fish production system in which only one fish species is reared in a culture system. The major fish varieties reared in monoculture system are trout, tilapia, catfishes, carps, shrimp etc. Monoculture of high-value, market-oriented fish species in intensive system is a common practice throughout the world. Supplementary feeding is compulsory to ensure production.

Polyculture is a fish production system in which two or more different fish species are farmed or culture of fish along with some other aquatic animals like shrimp or prawn. In this system of culture species with different habitats and different food preferences are stocked together in such densities that there will be almost no competition for food or space. Polyculture practices give higher yield than monoculture under the same conditions for freshwater carp farming.

Common fish species in Indian polyculture are catla, rohu, mrigal, silver carp, grass carp and common carp, and this system is sometimes called as composite fish culture. The biological basis of polyculture is different fish species grow together in a pond with difference in feeding and living behavour. The principal requirements of the different species in combination for polyculture are:  They must be different in feeding habits  They should occupy different columns in a pond system  They should attain marketable size at the same time  They should be non-predatory in behaviour

4. On the basis of enclosure used for culture:

Pond culture:

It is the most common method of fish culture. In this case water is maintained in an enclosed area by artificial construction of dike/bund, where aquatic

animals are stocked and grown. Ponds are usually filled by rain, canal water and by man made bores. They differ widely in shape, size, topography, water and soil qualities.

Cage culture is rearing of fish from juvenile stage to commercial size in a volume of water enclosed on all sides including bottom, while permitting the free circulation of water. Cage culture is readily adapted to water areas which cannot be drained. Fish culture in cage is an innovative concept to exploit the potential of lakes, reservoirs and riverine pools. In principle, almost every cultivable species of fish can be cultured in cages, such as carps, tilapia, trout, catfishes, etc. depending on socioeconomic, ecological and technical suitability.

Pen culture is defined as raising of fish in a volume of water enclosed on all sides except bottom, permitting the free circulation of water at least from one side. This system can be considered a hybrid between pond culture and cage culture. Mostly shallow regions along shores and banks of the lakes and reservoirs are used in making pen/enclosure using net/wooden materials where fish can be raised.

5. Raceway culture is defined as raising of fish in running water.

It is a high production system in which fishes are grown in higher stocking density. Raceways are designed to provide a flow-through system to enable rearing of much denser population of fishes.

Raceway ponds are basically of two types:

Linear type : Ponds arranged in sequence. In a linear type, the volume of water entering each pond is larger and as the same water is used repeatedly from pond to pond, occurrence of disease in initial ponds may directly affect the other connected ponds

Lateral type : Ponds laid out in parallel.n a lateral or parallel type the volume of water entering each pond is smaller but a fresh supply of water is always ensured, and no transfer of disease from one pond to another.

6. Recirculating Aquaculture System (RAS) can be defined as an aquaculture system that incorporates the treatment and reuse of water with less than 10% of total water volume replaced per day. The concept of RAS is to reuse a volume of water through continual treatment and delivery to the organisms being cultured. Water treatment components used in RAS need to accommodate the input of high amounts of feed required to sustain high rates of growth and stocking densities typically required to meet financial outcomes. Generally, RAS consist of mechanical and biological filtration components, pumps and holding tanks and may include a number of additional water treatment elements that improve water quality and provide disease control within the system.

7. On the basis of different farm integration:

Fish farming with agriculture: In the fish integrated agriculture system, fish culture is integrated with agricultural crops such as rice, banana and coconut, thereby producing fish and agricultural crops. Agriculture based integrated systems include rice-fish integration, horticulture-fish system, mushroom-fish system, seri-fish system.

Livestock integrated/ Animal husbandry fish farming: Livestock integrated fish farming system includes cattle-fish system, pig-fish system, poultry-fish system, duckfish system, goat-fish system, rabbit-fish system. In this integrated farming the excreta of ducks, chicks, pigs and cattle are used directly in ponds to increase plankton production which is consumed by fish or serve as direct food for fish. Hence, the expenditure towards chemical fertilisers and supplementary feeds for fish ponds are totally avoided reducing the production cost.

Fisheries can be categorised into two types – fin fisheries and non-fin fisheries. The former is fisheries of true fishes, whereas the latter is the fisheries of organisms other than true fish like prawn, crab, lobster, mussel, oyster, sea cucumbers, frog, sea weeds, etc.

Fin fisheries can be further categorized into two types – capture fisheries and culture fisheries.

Capture fisheries is exploitation of aquatic organisms without stocking the seed. Recruitment of the species occurs naturally. This is carried out in the sea, rivers, reservoirs, etc. Fish yield decreases gradually in capture fisheries due to indiscriminate catching of fish including brooders and juveniles. Overfishing destroys the fish stocks. Pollution and environmental factors influence the fish yield. The catches include both desirable and undesirable varieties.

Culture fishery is the cultivation of selected fishes in confined areas with utmost care to get maximum yield. The seed is stocked, nursed and reared in confined waters, then the crop is harvested. Culture takes place in ponds, which are fertilized and supplementary feeds are provided to fish to get maximum yield. In order to overcome the problems found in capture fisheries to increase the production, considerable attention is being given to the culture fisheries

Ornamental fish culture also known as aquariculture, is the culture of attractive, colorful fishes of peaceful nature in confined aquatic systems. Ornamental fishes are also called as “living jewels”.

A large number of freshwater ornamental fishes from India that belong to the family Cyprinidae are already known to the world. The family includes the colourful barbs and loaches which are abundant in almost all rivers and hill streams.

India has some of the finest ornamental fishes in the seas around Lakshadweep and Andaman and Nicobar Islands besides Kerala, Gulf of Mannar, Palk Bay and Gujarat. Notable amongst these are a number of species of damsel fishes, parrot fishes, surgeon fishes, wrasses and butterfly fishes.

India is still in a marginal position just contributing 1% of total ornamental fish trade. An estimate carried out by Marine Products Exports Development Authority of India shows that there are one million ornamental fish hobbyists in India.

Major countries involved in ornamental fish buying USA, EURPOE, JAPAN

Cage aquaculture involves the growing of fishes in existing water resources while being enclosed in a net cage which allows free flow of water. It is an aquaculture production system made of a floating frame, net materials and mooring system (with rope, buoy, anchor etc.) with a round or square shape floating net to hold and culture large number of fishes and can be installed in reservoir, river, lake or sea.

A catwalk and handrail is built around a battery of floating cages. There are 4 types of fish-rearing cages namely: i) Fixed cages, ii) Floating cages, iii) Submerged cages and iv) Submersible cages. Economically speaking, cage culture is a low impact farming practice with high returns and least carbon emission activity. Farming of fish in an existing water body removes one of the biggest constraints of fish farming on land, ie., the need for a constant flow of clean, oxygenated water. Cage farms are positioned in a such way to utilize natural currents, which provide the fish with oxygen and other appropriate natural conditions.

Conservation Mariculture which is the practice of stock enhancement of endangered, threatened and protected (ETP) species and depleted marine fish stocks for replenishment;

Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, an enclosed section of the ocean, or in tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish, including finfish and shellfish like prawns, or oysters and seaweed in saltwater ponds. Non-food products produced by mariculture include: fish meal, nutrient agar, jewellery (e.g. cultured pearls), and cosmetics.

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