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Fish Production

The marine fish production in India during 2004 had been estimated as 2.54 million tonnes, with a decrease of 1.9% compared to the previous year. The pelagic finfishes constituted 54%, demersal fishes 26%, crustaceans 15% and molluscs 5% of the total landings. The estimate of region-wise production showed that the north-east region, comprising West Bengal and Orissa coasts contributed 10.8% to the total production. South-east region consisting of Andhra Pradesh, Tamil Nadu and Pondicherry coasts contributed 24.1%.

The north-west region comprising Maharashtra and Gujarat coasts contributed 30.0% of the total, and south-west region comprising Kerala, Karnataka and Goa coasts recorded a maximum of 35.2%. Of the total landings, 68% was from mechanized sector, 25% from motorized and the rest 7% artisanal sector during the year 2004. Among the commercially important groups, oil sardine contributed 15% of the total landings during 2004, followed by penaeid prawns (7%), Indian Mackerel (6%), threadfin breams, croakers,ribbonfishes and non-penaeid prawns (5% each).

Analysis of trophic level of 707 species of commercially exploited marine fish and shellfish revealed that the production level is declining due to intense fishing and large predatory fishes are being replaced by small sized fish on the south-east coast of India. This result underlines the need for a shift toward ecosystem-based marine fisheries management.



The breeding, rearing and transplantation of fish by artificial means are called pisciculture or fish forming. Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. The most common fish species raised by fish farms are, in order, salmon, carp, tilapia, catfish and cod.

Increasing demands on wild fisheries by commercial fishing has caused widespread overfishing. Fish farming offers an alternative solution to the increasing market demand for fish and fish protein.

Major Categories of Fish Farms

Extensive aquaculture (local photosynthetical production) and intensive aquaculture (fish are fed with external food supply) are two major categories of fish forms.

1. Extensive Aquaculture
Limiting for growth here is the available food supply by natural sources such as phytoplankton, zooplankton etc. Tilapia feed directly on phytoplankton, which makes higher production possible. The photosynthetic production can be increased by fertilizing the pond water with artificial fertilizer mixtures, such as potash, phosphorus, nitrogen and micro-elements.

In order to available food sources in the pond, the aquaculturist will choose fish species which occupy different places in the pond ecosystem, e.g., a filter algae feeder such as tilapia, a benthic feeder such as carp or catfish and a zooplankton feeder (various carps) or submerged weeds feeder such as grass carp etc.,

Tilapia Carp

2. Intensive Aquaculture
In these kinds of systems fish production per unit of surface can be increased at will, as long as sufficient oxygen, fresh water and food are provided. Because of the requirement of sufficient fresh water, a massive water purification system must be integrated in the fish farm.

The cost of inputs per unit of fish weight is higher than in extensive farming, especially because of the high cost of fish food, which must contain a much higher level of protein (up to 60%) than cattle food and a balanced amino acid composition as well.

Aeration of the water is essential, as fish need a sufficient oxygen level for growth. This is achieved by bubbling, cascade flow or aqueous oxygen. Catfish, Clarias ssp. can breathe atmospheric air and can tolerate much higher levels of pollutants than trout or salmon. Intensive aquaculture does have to provide adequate water quality (oxygen, ammonia, nitrite, etc.) levels to minimize stress, which makes the pathogen problem more difficult. This means, intensive aquaculture requires tight monitoring and a high level of expertise of the fish farmer.




Specific Types of Fish Farms

Within intensive and extensive aquaculture methods there are numerous specific types of fish farms, each has benefits and applications unique to its design.

• Irrigation Ditch or Pond Systems
These use irrigation ditches or farm ponds to raise fish. The basic requirement is to have a ditch or pond that retains water, possibly with an above-ground irrigation system (many irrigation systems use buried pipes with headers). Using this method, one can store one's water allotment in ponds or ditches. In small systems the fish are often fed commercial fish food, and their waste products can help fertilize the fields. In larger ponds, the pond grows water plants and algae as fish food.

Control of water quality is crucial. Fertilizing, clarifying and pH control of the water can increase yields substantially, as long as eutrophication (depletion of oxygen by plant growth) is prevented and oxygen levels stay high. Yields can be low if the fish grow ill.

• Composite Fish Culture
In this system both local and imported fish species, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them having different types of food habitats. As a result the food available in all the parts of the pound is used. Fish used in this system include catla and silver carp which are surface feeders, rohu a column feeder and mrigal and common carp which are bottom feeders.

• Cage System
Fish cages are placed in lakes, bayous, ponds, rivers or oceans to contain and protect fish until they can be harvested. Fish are stocked in cages, artificially fed and harvested when they reach market size.

A few advantages of fish farming with cages are that many types of waters used and many types of fish can be raised and fish farming can co-exist with sport fishing. Concerns of disease, poaching, poor water quality, etc., lead some to believe that in general, pond systems are easier to manage and simpler to start.

Fish Cage

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