Prawn culture

Introduction
Indian aquaculture has been evolving from the level of susbsistence activity to that of an industry. This transformation has been made possible with the development and standardization of many new production and associated techniques of input and output subsystems. In recent years aquaculture has created great enthusiasm and interest among entrepreneurs especially for shrimp farming in coastal areas. Shrimp farming is capital intensive activity and uncontrolled mushrooming growth of it has led to outbreak of diseases and attributed environmental issues calling for closure of shrimp farms.

Although India has vast freshwater resources they are not fully exploited except for carp culture in limited scale. Fresh water fish culture employing composite fish culture technology has become popular for use in large number of tanks and ponds in the country. To meet the raw material required by the processing units for export demand there is urgent need to expand our production base. In addition it is always stressed that there is a need to utilise our natural resources productively to ensure the much needed food security.

Scope for Fresh Water Prawn Culture
Considering the high export potential, the giant fresh water prawn, Macrobrachium rosenbergii, the scampi, enjoys immense potential for culture in India. About 4 million ha. of impounded freshwater bodies in the various states of India, offer great potential for fresh water prawn culture. Scampi can be cultivated for export through monoculture in existing as well as new ponds or with compatible freshwater fishes in existing ponds. It is exported to EEC countries and USA. Since the world market for scampi is expanding with attractive prices, there is great scope for scampi production and export.

Technical Parameters
The giant freshwater prawn is suitable for cultivation in tropical and subtropical climates. It is a hardy species by virtue of its ability to adapt to various types of fresh and brackish-water conditions. It accepts pelleted feed and has omnivorous feeding habit. In the natural enviroment, lower reaches of rivers, tidal inlets, where water is directly or indirectly connected with sea are their preferred habitat specially during spawning. The breeding takes place in low saline waters which is also needed for larval and post larval development after incubation. Breeding of M.rosenbergii takes place in estuaries.

Though seed may be available in natural sources to a limited extent, for large scale culture there is a need to ensure regular supply of seed. For ensuring availability of quality seed in predictable quantity freshwater prawn hatcheries should be encouraged, technology for which is already developed. Freshwater prawn hatcheries are coming up in many states.

The techno-economic parameters required for establishment of prawn farm and its successful operation are briefly described in this booklet. The parameters are averaged out and the costs are only illustrative.

Site selection
The site selection plays an important role as the entire management aspect of the farm ultimately depends on specific conditions of the site. The aspects to be considered are topography of the area, soil type, availability of quality water etc.. The area should be free from pollution and flooding. Other considerations like approach roads etc. have also to be taken into account.

Soil quality
The ideal soil for Macrobrachium culture should be clay silt mixture or sandy loam comprising of 60% sand and 40% silt with good water retention capacity.

Water quality
There should be availability of abundant and good quality water.The water should be free from any kind of pollution. The pH should be maintained at 7 to 8.5. The temperature should range from 18 0 to 340C with an optimum range of 270 C to 310 C. Dissolved oxygen content should be higher than 75% saturation.

Pond construction
Rectangular ponds are suitable mainly from the harvesting point of view. A convenient width is 30-50 m, whereas length of the pond depends on site, topography and farm layout. Normally a size of 0.5 to 1.5 ha is found suitable. The average depth of the ponds should be 0.9m with a minimum of 0.75m and a maximum of 1.2m. Dike and pond slope may be kept at 2:1. Bund must have a freeboard of at least 60 cm above the highest water level in the pond. Designing and layout of the farms may be done keeping in view the water intake and water outlet facilities. The drainage system should be designed carefully to prevent mixing of outlet water with incoming water.

Water supply and drainage
Appropriate water supply and drainage systems have to be designed keeping in view the water source and topography of the area. Tubewell and pumping system may be considered if required for water intake/exchange. Water exchange on weekly or fortnightly basis as required is desirable and provisions are to be made accordingly.

Farm Management
The type of pond preparation to be adopted before stocking is based on the type of culture and its intensity and nature of the culture pond. Liming of the pond assumes great importance here than in the case of freshwater fish culture. The application of fertilisers is restricted in case pelletised feed is used. However, occasionally cow dung, single super phosphate, urea etc. can be applied on assessing the productivity.

The stocking density normally varies from 4000 to 50000 nos. of post larvae per ha depending on the type and intensity of the management practices. The culture system may be monoculture or polyculture with carps. In case of polyculture with carps the more pond depth is preferred at 4-5 feet. In case of polyculture the stocking density of prawn may vary from 2500-20000 post larvae. The carp fingerlings may be of the order of 5000 - 2500 Nos. Nursery may be incorporated where the post larvae obtained from hatcheries could be reared for a period of 4-5 weeks till they attain 40-50 mm or 1-3 gram.

In order to get desired production, feeding, aeration, water exchange, periodic monitoring should be continued. The quality and type of feed is based on culture system. Macrobrachium with its omnivorous feeding habits can make use of a variety of feeds from common wet feed made from rice bran and oil cake to scientifically formulated pelleted feed. The rate of feeding is determined by the stage of growth of prawn, water quality, density of stock and other manuring practices. Generally the feeding rate my be 5% of the body weight.

The duration of culture varies from 6 to 12 months depending on the type of culture practice. Generally in monoculture the culture period may be 6-8 months under monoculture and 8-12 months under polyculture. The average growth of prawn may range from 50 gms to 200 gms depending on the duration, density, water quality, feeding etc. The survival rate may range 50% to 70% depending on the type of management practices.

Extension services
The borrower should have experience in prawn farming and should be conversant with production technology, trade etc. Fish Farmers Development Agencies (FFDA) have been established in almost all districts for providing necessary training. The offices of Marine Products Export Development Authority (MPEDA) in most of the coastal states also provide necessary assistance.

Marketing
There is good demand for fresh water prawn in both local and international markets, as such there may not be any problem in marketing the same. Fresh water prawns can be sold directly by the farmers either in the market or to exporters for processing before export.

Capital Cost

Operational cost for one crop (6-8 months)

Source: http://www.nabard.org/