Annex II Country Reports (Cont.)

Annex II-5
INDIA

by

Dr. K. Alagarswami, Director, Central Institute of Brackishwater Aquaculture, Madras.

Shrimp farming on the east coast of India. The shrimp farming industry is developing rapidly in India, heightening awareness of sustainability and environmental issues.

1. SUMMARY

This report describes the current status of aquaculture in India, the present phase of development and future growth potential. It deals with the resources, technologies, production systems and environmental issues of aquaculture in general, and of carp culture and shrimp farming in particular. The institutional set up and organisational structure for co-ordinating both aquaculture research and development and environmental management, is indicated. Government policies and plans are conducive for rapid growth of aquaculture in India and the farmers, co-operatives and corporate sector are moving into aquaculture in a big way.

The influence of the external environment on aquaculture and of aquaculture on the environment is described in the general review. The same aspects are dealt with specifically in case studies of coastal shrimp culture and inland carp culture. The issues needing priority consideration for guiding and regulating aquaculture for its sustainable development are discussed. India has the Acts, with rules and regulations, to safeguard the general environment of the country, such as: the Wildlife (Protection) Act; Air (Prevention and Control of Pollution) Act; Water (Prevention and Control of Pollution) Act and the Environment (Protection) Act. The rules on Coastal Regulation Zones would cover inter alia coastal aquaculture, but no specific regulations have been framed as yet for aquaculture. Measures are, however, underway to rectify this. Research thrust areas on aquaculture with special reference to environmental management have been identified and the need for training and the strengthening of information exchange systems at the regional level have been outlined.

Map showing the States and Union Territories of India.

2. INTRODUCTION

India is endowed with vast natural resources for aquaculture (Figure 1) which, in terms of water and land resources, consist of: 8,085 km of coastline; 164,000 km of rivers and canals; 1.97 million hectares of reservoirs; 2.2 million ha of ponds and tanks; 1.3 million ha of beels, oxbow lakes and swamps; and 1.4 million ha of brackishwater areas. In terms of species resources, there are a large number of species of crustaceans, fish, molluscs, seaweeds (and other minor species) suited to all aquatic systems in the different agro-ecological and maritime zones of the country.

Aquaculture has traditionally been practised in India in both freshwater and coastal saline waters from time immemorial. These were characteristically low-input and low-production systems depending on wild seed collection and stocking in natural ponds, or impounding seed in large water bodies without any further management measures. During the last decade, aquaculture has been slowly but steadily transforming itself into a business activity. In freshwater carp culture, production rates of about 15 t/ha/year are attained and in shrimp culture yields of about 8 t/ha/crop have been achieved. In industrial golden tilapia culture, the production rate reaches over 400 t/ha/year in 3 crops. With increasing areas devoted to aquaculture and intensification of culture practices, environmental issues have come into focus as a point of discussion, particularly for planning and regulation aspects in the coastal sector.

This report examines the status of aquaculture development in India, the direction in which the industry is moving and the environmental issues which are gaining attention at the policy making and implementation level. In India, some strong environmental groups have seized on the problem of aquaculture development. The Central Government has an enlightened Department of Environment and Forests, with similar Departments at State level. All large aquaculture projects have to be vetted and cleared by the Central Department from the environmental angle. The case studies dealt with in this country report relate to shrimp culture in coastal areas and freshwater carp culture in Kolleru Lake.

Figure 1: Major river systems in India.

3. STATUS OF AQUACULTURE

The inland and coastal resource potentials of aquaculture are presented in Table 1.

Table 1. Inland and coastal resources of India.

3.1 Areas of concentration of aquaculture

Coastal/brackishwater aquaculture (primarily shrimp culture) is widespread on the East Coast, in the states of West Bengal (traditional bheries), Andhra Pradesh, Orissa and Tamil Nadu. Along the West Coast, Kerala has a dominant traditional system (paddy-cum-shrimp culture) which also exists on a moderate scale in Goa and Karnataka. Development of new shrimp pond systems has begun in north Maharashtra and south Gujarat. Area concentrations of shrimp farms are seen in Nellore, Bhimavaram and Kakinada in Andhra Pradesh and Tuticorin in Tamil Nadu.

Freshwater carp culture is widespread more in West Bengal, Madhya Pradesh, Uttar Pradesh, Orissa and Bihar. Area concentration of carp culture is greatest in Kolleru Lake.

Seafarming in India is largely in the experimental stage, with oyster farming and pearl culture in pilot project stage. Interest is growing for establishing joint-venture cage culture projects for fish such as sea bass and grouper.

3.2 Summary of aquaculture production in India

3.2.1 Production

Aquaculture production from 1987 to 1991 in inland and coastal waters is summarised in Tables 2 and 3, respectively. Under the Fish Farmers Development Agency programme, the average production rate was 1.97t/ha/year during 1991–92.

Table 2. Aquaculture production in freshwater pond systems in India (1 US $ = 31.25 Rs).

Source: 1990–91 Govt of India, Ministry of Agriculture, Fisheries Division; Rest from FAO (1992).
nd=no data available.

Table 3. Aquaculture production in coastal waters in India, traditional and new pond systems (MPEDA, 1992).

3.2.2 Species cultured and culture systems

Table 4 summarises the main species cultured in inland and coastal waters in India and the culture systems employed.

3.2.3 Species quantity

Production data for the individual species cultured are not available. Freshwater fish culture is mostly of the Indian major carps (catla, rohu and mrigal) and, to a lesser extent, exotic Chinese carps. Air-breathing fish have only a small production at present, but this is likely to pick up with improvements in seed production technology and the introduction of exotic species. In 1990, total inland fish production of India (species-wise) was: major carps 52.5%, common carp 8.9%, other carps 6.3%, murrels 3.9%, Hilsa 2.5% and others 25.9%. In traditional coastal shrimp farming systems, production is a mixture of several species of shrimps and fish. In the bheries of West Bengal, P. monodon comprises about 18% of total catch and in the pokkali fields of Kerala and Metapenaeus dobsoni constitutes more than 50% of total catch. P. monodon is the major species cultured in new brackishwater shrimp farming systems all over the country, with P. indicus in second place.

Table 4. Species cultured in India and culture systems.

3.3 Species market

Except for shrimp, which is exported to Japan, U.S.A. and EU countries, all other aquaculture products are used for domestic consumption.

3.4 Supply of inputs

Inland aquaculture
Fish seed farms in the country produced about 12,000 million carp fry during 1989–90. Wild seed are also used in some parts of the country. In extensive culture in rural tanks, feed is seldom used. In managed pond culture, cereal bran and oilcake form the basic ingredients and fish meal is incorporated whenever it is available. In industrial aquaculture production of tilapia, extruded pelleted feed is used. Better fish feeds of aquatic origin (tapping the locked up nutrients of ponds, lakes and wet lands) are expected to increasingly take over and mitigate problems.

The main species of fish used in polyculture are the Indian major carps Labeo rohita, Catla catla, Cirrhinus mrigala, Chinese carps Hypophthalmichthys molitrix, Ctenopharyngodon idella and common carp Cyprinus carpio. Low input polyculture using biogas slurry has also been developed for fish culture giving yields of 4.0–5.0 t/ha/yr. Yields of 4–5 tonnes per 6–8 months can be obtained in monoculture of murrels (Channa sp.), using dried marine trash fish as feed. Integrated fish farming with ducks, poultry and pigs and sewage fed fish culture is also practised. Macrobrachium rosenbergii is cultured in sewage fertilised ponds without supplementary feed and fertilisers. Yields of about 7.2 t/ha/yr of carps and 9.35 t/ha/yr of tilapia have been achieved in ponds treated with sewage effluent.

Coastal aquaculture
Traditional systems of coastal aquaculture are seen in the bheries of West Bengal, perennial and seasonal fields of Kerala, ghaznis in Karnataka and khazan lands in Goa. These are polyculture systems with a large component of miscellaneous fish and a smaller component of shrimps. Production depends on wild stocks that enter these fields, without any other inputs. Recently, some of the smaller farms have resorted to supplementary stocking and feeding to improve production.

A number of shrimp hatcheries of different capacities (20–200 million post-larvae/annum) have been established in the country and the total capacity is more than a billion shrimp fry per year. More hatcheries are under construction. Wild seed of P. monodon and P. indicus are still collected and used in West Bengal, Orissa and Andhra Pradesh. Similarly, a number of shrimp feed mills have been established by modification of animal feed manufacturing units and also some exclusive shrimp feed mills. The corporate sector imports shrimp feed from different companies in the Asia-Pacific region and they also supply feeds to their “franchise” farmers against supply of harvested shrimp to them.

The culture of finfish (Lates sp., Chanos sp. and mullets) is done in isolated patches due to non-availability of seed. Mullets are stocked with shrimp in extensive polyculture system. Oyster (Crassostrea madrasensis) and pearl oyster (Pinctada fucata) are cultured on a pilot scale at Tuticorin. Production technologies for mussel, clams, seacumbers and seaweeds have been developed with high production rates, but are not yet commercialised. Hatchery technologies have been developed for pearl oyster, oyster, mussel and clam. Holothurians have been bred in the laboratory, but these technologies have not been commercialised yet.

3.5 Legal framework for environmental management of aquaculture

3.5.1 Access to aquaculture operations

Definition of aquaculture
There is no legal definition as yet.

Relevant laws and regulations
Current rules and regulations governing the aquatic environment in India are summarised below:

Rules and Regulations

The Water (Prevention and Control of Pollution) Act, 1974. (Act No. 6 of 1974).
The Water (Prevention and Control of Pollution) Amendment Act, 1978 (Act No. 44 of 1978).
The Tamil Nadu Water (Prevention and Control of Pollution) Rules, 1983 (G.O.Ms.No.2) (Environment Control, 26th September 1983).
The Water (Prevention and Control of Pollution) Cess Act, 1977 (Act No. 36 of 1977).
The Water (Prevention and Control of Pollution) Cess Rules, 1978.
The Air (Prevention and Control of Pollution) Act, 1981 (Act No. 14 of 1981).
The Air (Prevention and Control of Pollution) Amendment Act, 1987 (Act No. 47 of 1987) (including noise) inserted in definition of air pollutant.
Tamil Nadu Air (Prevention and Control of Pollution) Rules, 1983. (G.O.Ms. No.3, Environment Control, 27th September 1983).
The Environment (Protection) Act, 1986 (Act No. 29 of 1986).
The Environment (Protection) Amendment Rules, 1987 (Notification dated 16th February 1987).
The Environment (Protection) Second Amendment Rules, 1987. (Notifications dated 16th April 1987).
The Environment (Protection) Third Amendment Rules, 1987 (Notification dated 18th April 1987).
The Environment (Protection) Act, 1986; Declaring Coastal Stretches as Coastal Regulation Zone (CRZ) and Regulating Activities in the CRZ; Notification S.O. 114 (E) dated 19th February 1991, Ministry of Environment & Forests (Department of Environment, Forests & Wildlife), Govt. of India.

The traditional system of brackishwater aquaculture (bheries, pokkali fields, khazan lands etc.) is governed and regulated by the individual State's land use policies and customary rights of owners and tenants. Very little change has been effected in these regulations, except in Goa where the Government recently enacted “The Goa (Brackishwater) Fish Farming Regulation Bill, 1991” (Bill No. 18 of 1991) to regulate and promote scientific fish farming in brackishwater land in the State of Goa.

The Ministry of Environment and Forests, Government of India, issued a Notification S.O. No. 114 (E) in 1991, under “The Environment (Protection) Act, 1986” declaring coastal stretches as Coastal Regulation Zones (CRZ) and regulating activities in the CRZ. This Notification has implications for coastal aquaculture, particularly those activities within 500 m from the High Tide Line. The “Indian Fisheries Act, 1897” enacted by the then Government of British India, which is still current, and under which the states have been empowered to enact their Acts, is an Act to provide for certain matters relating to Fisheries. Under this empowerment, the states have enacted Acts from time to time to regulate inland fisheries and marine fisheries as per their requirements. These are not, however, directly relevant to aquaculture.

Consent/authorisation
There is no system of licensing for aquaculture. Registration is optional and is meant for availing institutional credit, subsidies and technical assistance.

Special consent
Special permission is required for the conversion of agricultural lands for aquaculture and usually authorities in the District administration are empowered to issue such permission on a case by case basis. Under the Notification of Ministry of Environment and Forests, coastal aquaculture projects in the notified zone require clearance. The State Pollution Control Boards are authorised to issue No Objection Certificate/Permits for aquaculture projects. Some states have established Shore Development Authorities which also look into aquaculture projects. Special areas, like Kolleru Lake in Andhra Pradesh, have the Kolleru Lake Development Authority which looks into fish farm development.

3.4.2 Environmental management of aquaculture development

Water quality and water pollution control
Under the Environment (Protection) Act, 1986, standards for effluents have been laid down, but these are not for aquaculture. Specific standards for aquaculture effluent are not yet developed. State Pollution Control Boards are on their way to adopting standards. The database for such adoption is being collected as in Andhra Pradesh and the Central Institute of Brackishwater Aquaculture is engaged in a study in this respect.

Environmental impact Assessment (EIA)
EIA in aquaculture was adopted for the World Bank assisted IDA credit project on Brackishwater Aquaculture and Inland Fisheries in the country. All large projects of coastal aquaculture should do EIA and have the clearance of the Union Ministry of Environment and Forests. Clearance of smaller projects with a capital outlay of less than Rs 50 million is given by the State Governments. Procedures are still in the evolutionary stage. Many projects have already been established without EIA. In the freshwater sector no such requirement is in vogue. The Pollution Control Boards (PCB) have become aware of the environmental aspects of aquaculture and existing general regulation may be implemented.

Control of movement of fish
At Central Government level, a technical committee constituted by the Indian Council of Agricultural Research (ICAR) to examine all proposals for the introduction of exotic species of fish and shellfish to aquatic systems, is responsible for making recommendations. Within the country there is no legal control on the movement of fish. The spread of epizootic ulcerative syndrome (EUS) has largely been attributed to free movement of fish seed from affected regions to unaffected regions of the country. While there are quarantine departments for plants and animals, there are none for fish. Recently there have been instances of importation of tiger shrimp seed from Southeast Asian countries without quarantine. The need for development of a quarantine system and procedures for fish and shellfish has been realised and was discussed at a recent meeting of experts.

Control of chemicals
No regulations to control the use of chemicals and drugs exist. Pollution Control Board general regulations on effluent discharges include hazardous substances, but they are not specific to aquaculture. In some regions, there is indiscriminate use of chemicals and pesticides, particularly in shrimp farms.

Protected areas
Under the Wildlife (Protection) Act, 1972, National Marine Parks have been established. The prominent ones are the Gulf of Kutch and Gulf of Mannar Marine Parks. These are protected areas where no aquaculture can be carried out. The country also has declared Biosphere Reserves, such as the one for mangroves of the Sunderbans, where zonation has been carried out permitting or restricting certain activities. The mangroves of certain areas (e.g. Pichavaram forests in Tamil Nadu) are protected, but for such national programmes, there is no special zonation for aquaculture. Under the Notification of Union Ministry of Environment and Forests, each maritime state is expected to have its own coastal zone management plan, which would consider aquaculture zonation requirements, along with shoreline development. The zone up to 500 metres from the waterline along the sea is restricted against any construction activity.

Protection of endangered species
The Wildlife (Protection) Act, 1972 and schedules thereunder, have included certain species of aquatic organisms such as dolphins, dugong and turtles under the Red Data Book, but no species of aquaculture importance is on this list. Efforts have been made to catalogue the aquatic germplasm resources and draw up lists of endangered, threatened and vulnerable species of fish and shellfish.

Fish health
Establishment of health inspection of fish/shrimp seed is under consideration, but agencies with experts and facilities have not been created.

Product quality control
The quality control mechanism for exported marine products is well established in the country, but for domestic marketing of fish, there is no such system. Surveillance of fish markets by state Health Department inspectors is sporadic, and usually only when serious health problems are reported with consumption of fish, shellfish or turtle meat.

3.5 Compliance control and related problems and difficulties

The Fisheries Departments, Forest Departments and Pollution Control Boards in the states are armed with powers to ensure compliance of Government orders issued under statute and to punish those who contravene the rules. Mechanisms for enforcement are, however, generally protracted. Specific regulations for aquaculture are under development. Some states are considering enacting legislation for aquaculture development.

3.6 Institutional set up related to aquaculture and development

3.6.1 Central organisations

3.6.2 State agencies

4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW

4.1 Impacts of external environment on aquaculture production

4.1.1 Inland aquaculture

Physical factors
India is situated in the tropical monsoon belt with the south-west monsoon in summer and the north-east monsoon in winter. Heavy rains in the catchment areas cause flooding of rivers and damage to farm structures and stock. The flood plains of the Ganga and Brahmaputra, covering the north and north-eastern parts of India, are subject to such calamitous situations periodically. Flash floods of a local nature also cause similar damage and the Panchayat level rural ponds are affected.

All major rivers originate in mountain ranges, such as the Himalayas, the Western Ghats and the Vindhyas, and course several hundred kilometers before their confluence with the sea. The rivers thus carry heavy loads of sediments which get deposited in the flood plains, reservoirs, tanks and ponds leading to severe siltation problems. The river Ganga has an annual runoff of 493 km³ and carries 616 million tonnes of suspended solids. The Mahanadi area of Orissa and Godavari area of Andhra Pradesh (which are well known aquaculture areas) have serious sedimentation problems. Similarly, the river Narmada carries a heavy silt load into the Gulf of Cambay, which has one of the heaviest suspended loads in the coastal waters. Sukhna Lake in Chandigarh lost almost three quarters of its capacity in just 30 years due to siltation. Dal Lake in Kashmir is expected to disappear in less than 50 years and the bed of Kolleru Lake in Andhra Pradesh is rising at a rate of 2.5 cm per year due to siltation (WWF, 1992). The impact of siltation from the catchment area of Gandhi Sagar is being studied.

In the northern latitudes of India, winter temperatures are very low (dropping to 2–10°C), which affects aquaculture as the species cultured are mostly tropical species. Survival and growth is very poor, restricting farming operations. High temperatures in summer throughout most of the country result in water shortages which again restricts aquaculture. In the peninsular region, the seasonal tanks hold water only for 3–4 months and in some years, due to poor rainfall, the tanks remain totally dry affecting aquaculture production.

Domestic sewage
Untreated or semi-treated sewage is discharged into rivers, lakes and estuaries from all but a few towns and cities in India. The immeasurable quantities of organic matter added to these waterbodies increases the BOD and causes depletion of dissolved oxygen levels. The total volume of discharge from the environs of Bombay is around 365 million tonnes per year and of Calcutta around 350 million tonnes. The Mahim Bay (Bombay) receives 64 million tonnes of domestic sewage and 0.9 million tonnes of industrial effluent every year. There are similar problems in the Kulti estuary which receives city sewage from Calcutta. The nutrients (phosphates and nitrates) which are present in domestic sewage and agricultural runoff, accelerate the process of eutrophication. Sewage discharge and eutrophication has affected most of the lakes in Kashmir. A deterioration in water quality has also been observed in the backwaters of Cochin (Kerala) as well as Yamuna river near Delhi which are contaminated with sewage (WWF, 1992).

Agricultural wastes
India, as one of the major agricultural countries, uses 5 million tonnes of fertilisers, 55,000 tonnes of pesticides and 125,000 tonnes of synthetic detergents (Qasim and Sen Gupta, 1982). It is estimated that nearly 25% of all these ultimately find their way through the rivers into the marine environment. At farm level, with aquaculture proving far better than agriculture economically, aquaculture farms have come up in the midst of rice paddy, wheat and sugarcane fields through conversion. This is particularly noticeable in Punjab and Andhra Pradesh, the two leading agricultural States in India. Given the relaxation in Government's land use policy, a radical change with a tilt in favour of aquaculture will take place in several other states. This may result in agricultural drainage water with pesticides and nutrient loads being used in aquaculture ponds, which will ultimately affect aquaculture production.

Industrial effluents
Industrial effluents discharged into the sea by coastal industries have been estimated at 0.39 billion m³ per year (Sen Gupta and Kureishy, 1989). The concentration of heavy metals in the estuarine region of River Hooghly has been estimated to be 1.45% of total suspended solids. Pollutants present in industrial effluents show a great diversity in composition. They range from toxic heavy metals such as cadmium, lead, mercury and arsenic released from electroplating, chemical and metallurgical industries; to effluents rich in organic substances from sugar refineries, distilleries, breweries and leather tanneries. With increasing industrialisation, the threat from industrial effluents is assuming alarming proportions. Areas such as the Mandovi estuary in Goa and the Pune-Sholapur reservoir in Maharashtra are particularly threatened (WWF, 1992). Aquaculture expansion in the inland water bodies would need to exercise caution against pollutants from the industrial sector.

Aquatic weeds and algal blooms
Weeds such as water hyacinth (Eichhornia crassipes), pond weed (Potamogeton), Ipomea aquatica, Salvinia molesta, S. natens and Paspalum distichum block waterways and irrigation canals, increase siltation rates and reduce biological diversity (WWF, 1992). The water hyacinth is a menace in a large number of inland waterbodies and also affects aquaculture production. The backwater system of Kerala and the bheries of West Bengal are largely affected by weeds. Bheri farmers consider some of the weeds such as Naja and Ruppia as beneficial for shrimp culture. Many shrimp farms in Andhra Pradesh have been infested with weeds. Algal blooms, depletion of dissolved oxygen and consequent production losses in inland and coastal ponds have been experienced, particularly in summer months when water exchange becomes difficult.

4.1.2 Coastal aquaculture

A recent review of the environmental problems of some of the important coastal ecosystems in India and the effect on aquaculture and aquatic production provides a good understanding of the process of change that has taken place over a period of time in India (Alagarswami, Ms, 1993). This report should be consulted for more detailed information.

Physical factors
The construction of Farakka barrage on Hooghly river and Thannermukkom bund in Vembanad Lake, and land reclamation for non-fishery purposes in several places have imposed constraints on aquaculture.

The east coast of India is subject to frequent cyclonic storms and occasional tidal waves. On 9th May 1990, a cyclonic storm hit the coastal districts of Andhra Pradesh, namely Nellore, Krishna, West and East Godavari districts. The shrimp stocks had been harvested in April and damage was confined only to physical structures. In East Godavari District, the farms were inundated almost one metre above bund level due to heavy rains. The damage included erosion of bunds, heavy siltation and damage to electrical installations, sluices, shutters and screens. Communications were cut off and feed stocks were lost. In West Godavari and Krishna Districts, seawater had intruded far inland, damaging the farm structures including farm buildings (CIBA, 1991). A similar situation was experienced in November 1991, with heavy rainfall due to a cyclonic depression. With the breaching of 202 irrigation tanks in Nellore District, large-scale inundation of the entire watershed area was experienced. All the shrimp farms were submerged causing severe damage to structures, installations, equipment and standing stock. The total loss to the Fisheries sector alone was estimated at about Rs. 9 million (CIBA, 1992). Some parts of the Tamil Nadu and Orissa coasts, where shrimp farms have been developed, are also vulnerable to cyclonic storms and floods.

Salinity fluctuations often cause difficulties in pond management. From near freshwater conditions during monsoon, it goes up to 45–47 ppt in summer in the estuarine regions of the peninsular India, particularly on the east coast. A shrimp farm at Radhanallur in Tamil Nadu had to take a crop under the severest conditions. Many shrimp farms suffer low salinity conditions and salinity drops to less than 28 ppt in the open coastal waters, which interferes with shrimp hatchery operations. Ambient temperatures rises to above 40°C and drops to 15–10°C affecting farm production and hatchery operations. Farms (such as the one at Poyya in Kerala) constructed in acid sulphate soils have never been able to show production results.

Several records of red tides in the open coastal waters exist, but these have not been of any consequence to aquaculture so far. However, with the increase in shrimp farming, coastal red tides could affect operations and production. Paralytic shellfish poisoning (PSP) leading to death of a few persons who had consumed backwater clam, Meretrix casta, collected from brackishwater areas near Madras and Mangalore has been reported. Monitoring of coastal waters near Mangalore has been initiated.

4.2 Contamination of aquaculture products

No information is available on contamination of aquaculture products. Aquaculture production based shrimp exports have not faced any contamination problems. Oyster production at Tuticorin is at safe levels for all parameters. Depuration of cultured molluscs has been established as a practice at Tuticorin. Mussel production in coastal waters has not faced any problems, however, with the fast expansion of the coastal aquaculture industry, monitoring for pathogens and heavy metals is considered essential.

4.3 Impacts of aquaculture on the environment

4.3.1 Inland aquaculture

Physical factors
Flood plains of North Bihar, West Bengal and north east India have been experiencing, in some areas of development of pond culture of carps, problems of higher nutrient levels in the drainage waters of fish ponds which enrich algal blooms and cause eutrophication. These are, however, occasional and in local pockets. With the development of integrated farming, the problem is likely to be mitigated in future.

With increasing intensity of aquaculture in enclosed and semi-enclosed systems, water bodies are likely to experience eutrophication due to the discharge of heavy organic loads and consequent algal blooms. The oxbow lakes are likely to be affected by this problem.

Chemical factors
Chemical fertilisers are used in the semi-intensive polyculture of carps, such as in Kolleru Lake (Andhra Pradesh). Also to control spreading parasitic problems, chemicals and drugs have come into use, promoted by pesticide dealers in the area. In seed farms, HCG, LHRHa and “ovaprim” are used for induced maturation of carps. The impact of residual hormones and drugs in fish and in the aquatic system is not known. Inappropriate application of antibiotics and other chemotherapeutants in aquaculture systems is likely to give rise to public health issues. Several chemicals in use (such as malachite green, malathion and grammoxone) are potentially harmful to users. No regulations exist on the availability or withdrawal periods of aquaculture therapeutants. A more detailed study on the use and impact of chemotherapeutants is required to assess problems and develop policies and guidelines for their use. The use of cowdung, mahua oil cake and bleaching powder in aquaculture sometimes causes concern in areas where pond water is used for drinking or bathing (ADB/NACA, 1991).

Interactions between aquaculture and native species
The escape of silver carp in natural/manmade impoundments has reduced the abundance and fishery of Catla in Gobindsagar, Madhya Pradesh. Increasing culture of common carp and Chinese carps may lead to their affecting natural fish habitats, especially Indian major carps. Tilapias entering carp ponds have reduced productivity, especially in West Bengal. Oreochromis niloticus has already found a place in the farming system, although it has not been officially permitted. The “Golden Tilapia” is intensively cultured near Madras.

The channel catfish, Ictalurus punctatus, has been introduced in a commercial farm in Tamil Nadu and more recently the African giant catfish (Clarias gariepinus) has also been imported into Tamil Nadu. These two species are said to be bred and cultured in controlled systems. The escape of the species, if it occurred, and possible interactions with the native species are not known.

Social conflicts and aquaculture
In Andhra Pradesh, the spectacular growth of carp culture has led to the conversion of paddy fields to fish ponds. A similar situation exists in the Punjab and is being witnessed in the River Cauvery delta basin tail end areas in Tamil Nadu. This is causing concern to Governments as large-scale conversion to fish culture will reduce paddy lands and thereby affect cereal production, which is the staple food of people, particularly the poor.

Irrigation tanks are under the control of the Public Works Department of the State Governments and fish culture is not considered as an integrated resource use by the irrigation authorities. The Government of Andhra Pradesh is planning to impose a tax on water use for aquaculture.

4.3.2 Coastal aquaculture

Physical factors
Shrimp farming along the coastal area of the whole country is developing at a rapid rate. Huge cyclone protection dykes and peripheral dykes are constructed by the shrimp farmers. In many cases, as in Kandleru creek (Andhra Pradesh), the farm areas are the natural drainage areas for floods. Due to physical obstruction caused by the dykes, the natural drain is blocked and flood water accumulates in the hinterland villages. Protests are being made by people in some of the villages against such dykes. The ponds are constructed right on the bank of the creeks without leaving any area for draining of flood water.

Right of passage of coastal fishermen
The shrimp farms do not provide access to the beach for traditional fishermen who have to reach the sea from their villages. As farms are located and entry is restricted, the fishermen have to take a longer route to the sea for their operations. This is being objected to by traditional fishermen.

Drinking water problems
The corporate sector has purchased vast areas adjoining the villages which, in some cases, include drinking water public wells of the villages. The villagers cannot use these wells anymore as they are located in private land owned by the farmers. This is causing social problems.

Salinisation
It is reported that salinisation of land is spreading further landwards and the wells yield only saline water. In Tamil Nadu and Andhra Pradesh protests have been voiced against salinisation. Some of the socially conscious shrimp farm operators are providing drinking water to the affected villages by laying a pipeline from their own freshwater source wherever available. Apart from wells, the agricultural farms adjoining the shrimp farms are reported to be affected. However, there is increasing conversion of paddy fields as in the Bhimavaram area of Andhra Pradesh and even on the fringes of Chilka Lake into shrimp farms. In the semi-arid saline tracts of Haryana and Rajasthan, the subterranean brackishwater (more than 50–80m in depth) is being brought up for use in brackishwater aquaculture (now experimental) which might spread salinisation further in the top soil.

Mangrove areas
The status report on mangroves of India published by the Ministry of Environment and Forests (GOI, 1987) is shown in Table 5. In the earlier years, vast areas of mangrove were destroyed for agriculture, aquaculture and other uses. In the more recent years, the mangroves have been protected by law. However, the satellite imagery pictures show destruction of mangroves in Krishna and Guntur Districts of Andhra Pradesh for construction of shrimp farms. Gujarat State is planning major shrimp culture programmes in the Narmada region adjoining Gulf of Cambay. Protection of mangroves should receive attention.

Table 5. Distribution of mangrove forest in India (GOI, 1987).

Natural seed resources
The demand for shrimp seed (particularly P. monodon) is growing with the expansion of shrimp culture and hatchery production is unable to meet it. Exploitation of natural seed resources is growing unabated, particularly in West Bengal, Orissa and Andhra Pradesh. Seed collection in West Bengal has reached the status of a small-scale industry with thousands of rural folk engaged in collection and a vast network of local seed market and transportation. Supplementary stocking of bheries has created an insatiable demand. Similarly, demand for tiger and white shrimp seed is increasing for stocking in “pokkali” and perennial fields of Kerala. The wild seed resources in general are overexploited. A study by the Central Institute of Brackishwater Aquaculture, from its Kakdwip Research Centre in West Bengal has revealed the following situation (Banerjee and Singh, 1993):

Seed collection activities are much more pronounced in North 24 Parganas, as about 90% of the bheries are located in that area. The total number of shrimp fry collectors in both districts may be more than 50,000. The percentage contribution of P. monodon was 1.5%, 36% and 0.6% respectively at Najat, Harwood Point and Ramnagar; the remaining shell and finfish juveniles were killed in the process. Das (1987) reported large-scale destruction of shrimp and fish fry in the Hugli-Matla estuarine system. Verghese et al (1988) reported 25,000–100,000 post larvae of M. monoceros occurring in the shootnet collections in the Muriganga estuary per net per hour. Our own data suggests that for every P. monodon fry caught, the total number of other species caught is as high as 190.9 at Ramnagar.

The impact of wanton killing of various shrimp fry can be observed from the fact that out of 10,754.9 tonnes of fish landings from the Hugli-Matlah estuary during 1970–71 (pre-Farakka period), shrimp contributed 1,975 tonnes, forming 18% of the landings. Although the total fish landings from the Hugli-Matlah estuary has increased considerably during the recent past (Anon, 1988–89, 1989–90), the percentage contribution of shrimp has declined to 8.1% in 1989–90. The increase in total fish landings has been attributed to the significant increase in fishing effort, especially Hilsa gear, along with increased craft. The introduction of modern synthetic gear employed for catching Hilsa ilisha and other fish during the winter fishery are plausible reasons for the increased catches.

The enormous quantity of shrimp fry by-catch destroyed constitutes fry of both economic and uneconomic varieties. Among the uneconomic varieties of shellfish caught commonly as fry by-catch are crustaceans, Nematopalaemon tenuipes and the larvae of Varuna litterata. The uneconomic finfish landed are Haplochilus panchax, Plotossus canius, Anguilla sp., Ambassis sp., Equula ruconius, Gobius sadanundio, Cynoglossus sp. and Arcochiron sp. In practice, a shootnet collects many hatchlings and early fry of fish and post larvae of shrimp, which have a major role to play in the food chain of predatory fish. So elimination of fry in the fry by-catch is not only detrimental to the predators thriving on them, but it also creates an ecological imbalance. The large quantities of fry by-catch are discarded by the fry collectors because:

1. Their value is insignificant, relative to that of P. monodon.

2. No fry trade for other commercially important fish and shellfish exists.

3. The fry collectors lack education.

4. The poorer fry collectors receive advances from the traders/agents only for tiger shrimp fry collection, which is the only organised fry trade in West Bengal.

In another study, Nielsen and Hall (1993) developed nursery rearing techniques for tiger shrimp seed in floating cages in Ramnagar, Medinipur district, West Bengal. The objective was to introduce a technology by which the fry-catchers could augment their income by nursing the shrimp fry to a larger size. The study concluded that natural variations in fry availability and water levels in the canals of the area prejudice the profitability of cage culture and that several more years of trials will be required to evaluate the impact of such environmental fluctuations.

People's awareness
People in general have become aware of the environmental issues related to aquaculture. A current case in point is the agitation against a large commercial farm coming up in Chilka Lake (Orissa). People have demanded an EIA of the project. People in Nellore District in Andhra Pradesh have raised environmental issues and called for adoption of environmentally-friendly technologies and rejection of “imported” technologies from regions which have suffered environmental damage. Protests have been voiced by the local people in Tuticorin area in Tamil Nadu. Both print and visual media take up environmental issues with a great deal of zeal. This appears to augur well for regulating coastal shrimp farming with eco-friendliness.

Technology-related problems
The confined shrimp pond culture on the fringe of Chilka Lake is based on utilisation of soil salinity and monsoon rains accumulating in the ponds. There is no water intake or drainage from these ponds. This is a static and captive system which operates from July to February for 2 crops every year. This is a fragile ecosystem which has to be closely monitored on a continuous basis for long-term impact on the environment.

In intensive farming, stocking densities are on the increase. In one instance, P. indicus was stocked at 70 post larvae/m², almost reaching the levels of Taiwan before the disease outbreak in 1988. This necessitates heavy inputs of high energy feeds, the use of drugs and chemicals and good water exchange. The organic load and accumulation of metabolites in the water drained into the sea should be very high as could be seen from the dark-brown colour and consistency of the drain water.

In extensive farming in Andhra Pradesh, the farmers use their own formulated feed using trash fish, beef, rice bran and oilcake in moist dough ball. The feed is not of constant composition and varies almost daily with the availability of ingredients. A study of FAO/BOBP of this system in 1990 brought out the following impact on the environment:

1. The mud colour at the bottom of the ponds at the time of harvest was distinctly black in colour indicating feed decomposition and anaerobic conditions.

2. The average DO level of the local pond supply water had been steadily decreasing over the last 10 years, from a high of 9 mg/l to its present level of 4–5 mg/l. This situation may be the result of the steady rise in the number of shrimp ponds becoming operational in this region (Kakinada) of Andhra Pradesh. The shrimp farms are drawing water from, and discharging pond drainage water back into, the same supply creek. The increasing use of fertilisers and other agrochemicals on rice crops and the drainage of field water into the same creeks only adds to the problem.

3. Although the quality of creek water was considered (by the local staff) to be somewhat worse than normal (possibly as a result of the earlier cyclone), it is evident that the shrimp farmers are attempting to grow shrimp under conditions which are highly variable and difficult to control.

Chemicals and drugs have recently come into use in shrimp farms in Andhra Pradesh. There is a vigorous marketing effort by traders dealing with agricultural pesticides and veterinary drugs to sell these to shrimp farmers. Data on these aspects are being collected and complied by the Central Institute of Brackishwater Aquaculture. At the present stage of development, there is no evidence to show that the use of drugs and chemicals is of much significance. Ponds in Nellore, Andhra Pradesh, which had shown stunted growth of P. monodon; blooms of luminescent bacteria (Vibrio fischeri) and pathogenic luminescent bacteria; retarded growth and mortality due to Bacterial Septicaemia disease (caused by the pathogen V. alginolyticus); and high values of COD during the peak disease period, were given multiple treatments involving greater water exchange, KMnO₄/iodine treatment application of “health stone” (zeolite) and the bacterial formulation “BN-10”. This was found to improve water quality and result in a drop in the mortality rate.

Shrimp hatcheries have periodic problems with disease and mortality of larvae, particularly in the mysis and postlarval stages. Bacterial infection with V. alginolyticus and luminescent bacteria V. harveyi have been seen to cause these problems. It is reported that most hatcheries have faced the problems of bioluminescence in the rearing water leading to mortality. Also disease due to fungus has also been noted. All these have been caused by the routine use of antibiotics in the rearing water in high-tech hatcheries as a preventive measure from the initial stage and such treatments are continued to ensure production.

Information base
The Central Institute of Brackishwater Aquaculture has initiated a survey of shrimp farms in the country and the field work in 9 districts in Andhra Pradesh and 4 districts in Tamil Nadu has just been completed. The survey questionnaire includes specific sections on environmental issues, as well as coverage of overall farming operations. It is planned to extend the survey to other states in a phased manner in the future. In addition, a specific survey of the Kandleru creek-based farming and seawater-based shrimp culture in Nellore district of Andhra Pradesh has just been completed. Water quality, soil characteristics and biological production of the farms has been studied. Another study on engineering aspects of Kandleru creek to consider a proposal for construction of a separate drainage canal on either side of the creek, along its entire 34 km stretch, has been completed by an engineering group with the co-operation of farmers. On examination of the data, cost and logistics, the proposal has not been found feasible at the present juncture.

Sea level rise and related environmental issues for coastal aquaculture
The increase in CO₂ and other gases released into the atmosphere by human activities is causing the greenhouse effect bringing an increase in temperature (of about 1–4.5°C) leading to global warming which would also result in sea level rise. The level of rise has been predicted variously by different authors and the ranges are 12–50 cm by the year 2025; 20–140 cm by 2050; and 20–180 cm by 2075.

According to Chua and Paw (1990), these changes will have an impact on aquaculture in the following areas:

1. Metabolic activity related to temperature-growth in sub-tropical regions.

2. Prolonged high temperature may result in mass fish kills in shallow ponds.

3. Growth and reproduction will be influenced by seasonal fluctuations in flood plains, rivers and lakes.

4. Interspecific competition and changes in distribution of species.

5. Variations in physiological responses and habitat adjustments will be required.

6. Sessile organisms like oysters and mussels will be vulnerable and local extinction may occur.

7. Engineering changes in pond construction and net cage culture may be required.

8. Erosion of ponds in coastal areas.

9. Siltation of culture beds like mudflats and intertidal areas.

10. Sediment load will affect productivity of coastal waters.

11. Cages and pens will be vulnerable to inclement weather conditions.

12. Changes in culture sites may become necessary.

13. Seed grounds may shift.

14. May affect distribution and prevalence of diseases of cultivable species.

The authors remarked that “In the case of Taiwan and India, for instance, much of their territories may experience a warmer climate. Thus, the geographical range of culture for tropical species in these two areas will extend towards the north”. They concluded that “It is imperative that national aquaculture development efforts, policies and plans be reviewed to incorporate climate risk factors attributed to the greenhouse effect”.

The Indian subcontinent has the north-east and south-west monsoon system and is subject to periodic cyclones, tidal waves and storm surges, more along the east coast. The tidal amplitude is relatively low in the southern region (about 70 cm high tide) and progressively increases towards the north (about 7 m). Brackishwater aquaculture is concentrated more along the east coast and south-west coast as compared to the north-west coast. These locational factors in the light of predicted global warming and sea-level rise could bring about considerable changes in aquaculture in India.

5. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: IN DEPTH STUDY

5.1 Shrimp pond culture in India

5.1.1 Introduction

The area under shrimp farming in India is shown in Table 6 (MPEDA, 1992) giving state-wise details of total brackishwater area, area under culture and production during 1991–92.

Table 6. Shrimp farming in India during 1991–92.

National average production rate: 586 kg/ha/annum (Source: MPEDA, 1992).

Since the above estimate was prepared, shrimp farms have increased in number and extent. A current estimate of about 80,000 ha would not be wide of the mark. Andhra Pradesh and Tamil Nadu are two states where the increase in area is phenomenal. The capital investment for development of about 30,000 ha (leaving about 50,000 ha already under the traditional system), would be of the order of Rs 3– 4 billion, not including the land cost. Using the national average shrimp production rate of about 600 kg/ha/year, the production estimate is about 48,000 tonnes with a farm gate value of about Rs 7.2 billion. The farming sector alone would employ about 30,000–40,000 people on a full time basis, with several thousand others working on part-time basis involved in pond construction, preparation and harvesting.

5.1.2 Types of technology - changes in technology with time

Traditional: Practised in West Bengal, Kerala, Karnataka and Goa, also adopted in some areas of Orissa. Coastal low-lying areas with tidal effects along estuaries, creeks and canals; impoundments of vast areas ranging from 2–200 ha in size. Characteristics: fully tidally-fed; salinity variations according to monsoon regime; seed resource of mixed species from the adjoining creeks and canals by auto-stocking; dependent on natural food; water intake and draining managed through sluice gates depending on local tidal effect; no feeding; periodic harvesting during full and new moon periods; collection at sluice gates by traps and by bag nets; seasonal fields alternating paddy (monsoon) crop with shrimp/fish crop (inter monsoon); fields called locally as bheries, pokkali fields and khazan lands.

Improved traditional: System as above but with stock entry control; supplementary stocking with desired species of shrimp seed (P. monodon or P. indicus); practised in ponds of smaller area 2–5 ha.

Extensive: New pond systems; 1–2 ha ponds; tidally fed; no water exchange, stocking with seed; local feeds such as clams, snails and pond-side prepared feed with fishmeal, soya, oilcake, cereal flour etc.; wet dough ball form; stocking density around 20,000/ha.

Modified Extensive: System as above; pond preparation with tilling, liming and fertilisation; some water exchange with pumpsets; pellet feeds indigenous or imported; stocking density around 50,000/ha.

Semi-intensive New pond systems; ponds 0.25 to 1.0 ha in size; elevated ground with supply and drainage canals; pond preparation methods carefully followed; regular and periodic water exchange as required; pond aerators (paddle wheel) at 8 per ha; generally imported feed with FCR better than 1:1.5 or high energy indigenous feeds; application of drugs and chemicals when need arises; regular monitoring and management; stocking density 15–25/m².

Intensive: Ponds 0.25–0.50 ha in size; management practices as above; 4 aerators in each pond; salinity manipulation as possible; central drainage system to remove accumulated sludge; imported feed; drugs and chemicals used as prophylactic measures; strict control and management; stocking density 20– 35/m².

Changes in technology: As already indicated. The initial concept and practice was to develop tide-fed systems, this slowly gave way to a pump-fed systems. Presently, the emphasis is on seawater based farming systems for P. monodon with a water intake system extending far into the sea with submerged pipelines, pier system and gravity flow. From sandy clay soils, the present coastal farms are located in sandy soils also with seepage control provisions.

5.1.3 Management and legal regime for access to shrimp culture

Aquaculture has been classified as an industry for certain purposes. Hence, large operations are required to follow the rules and regulations as applicable to industry. Small farmers do not need to obtain any licence as the farms are developed on their own land and in interior places. Environmental clearance is required in all cases as per Ministry of Environment and Forests Notification. Bank finance is released only after obtaining all clearances as required. The small farmers who operate with their own and private finance seldom take any steps to get clearance.

5.1.4 State-by-state analysis

I. West Bengal

The “bheries” constitute one of the important fishery resources in the estuarine wetlands of the upper and lower Sunderbans of West Bengal. With a waterspread area of about 33,000 ha spanning the low, medium and high salinity zones, the bheries form a major shrimp and fish production system in India. The bhery fishery, locally known as “bhasabhadha” lands, have developed through the ages in tidal wetlands, namely mudflats, swamps, marshes, paddy fields etc. in the districts of 24 Parganas (North and South) in West Bengal. This traditional system is reported to have first developed in the spill area of the River Bidhyadhari near Calcutta city which was silted up due to sewage discharge. A portion of the river and spillway were embanked and converted into lucrative bheri fisheries. Later, the system was developed in the lower deltaic region, the Sunderbans, with the advancement of transport facilities. The main sources of water for bheri fisheries are the estuaries of Saptamukhi, Thakuran and Matla (in the Hooghly-Matla estuarine system) and other minor estuaries like Gosaba, Muriganga, Harin-bhanga, Kulti, Ichamati, Raimangal etc. with their tributaries.

The total number of bheries in West Bengal is about 1,334 covering an area of 32,930 ha spread over three salinity zones, namely the medium salinity zone (15,613 ha), low salinity zone (9,844 ha) and high salinity zone (7,472 ha). The bheries are irregular in shape and range in size from 2 ha to 267 ha, the average size being in the range 15–34 ha in the three salinity zones. The bheries are of seasonal and perennial types. Seasonal bheries dry up during November-December and are left exposed to sun for about a month till next season starts. Both fish and paddy are raised in the same unit in a sequential manner, sometimes in conjunction. These mainly exist in low and medium salinity zones. Perennial bheries exist mainly in high saline zones in the southern part of the Sunderbans. Fish and shrimps are raised almost throughout the year. The bed of these bheries is not generally dried and paddy is not grown here due to high salinity.

Low salinity bheries are located in the north of District 24 Parganas at Barasat, Swarupnagar, Deyganga, Rajarhat and Baduria. Salinity does not generally rise above 10 ppt in summer and is about freshwater level during the monsoon. Paddy is grown during July-November along with freshwater fish. P. monodon is extensively cultured along with mullet (Liza parsia) during January-June. The average production is about 878 kg/ha/year with P. monodon contributing 70 kg/ha/year. Medium salinity bheries exist in the north-east region of District 24 Parganas at Haroa, Minakhan, Hashnabad, Basirhat and Hingalunge. Salinity does not rise above 20 ppt in summer. Minimum values are recorded during the monsoon. The average production of fish and shrimp is about 749 kg/ha/year with a shrimp component of 214 kg/ha/year. The high salinity bheries are located in the south of the Sunderbans at Canning, Mathurapur, Joynagar, Patharpratima, Basanti, Kultali, Gosaba, Sandeshkali, Kakdwip etc. Salinity is 30–37 ppt in summer and during monsoon it does not drop below 6–7 ppt. The average production is about 694 kg/ha/year with a P. monodon component of 84 kg/ha/year. A number of species of brackishwater fishes are reared along with shrimps.

The total production of fish and shrimps in all the bheri systems is about 25,518 tonnes per year with an average production rate of 775 kg/ha/year. P. monodon accounts for 18% of the total production. The bheries which used to be auto-stocked with the young of shrimps and fishes, are now additionally stocked with P. monodon seed collected from the wild. This has led to very successful seed collection and trade in 24 Parganas (North and South) Districts during the last 10–12 years. Farmers resort to supplementary stocking at 40,000–50,000 P. monodon seed/ha. No supplementary feeding is done due to the vast area of bheri. Harvesting of shrimp is done during April-July in low and medium saline bheries and during May-June in the high saline bheries. Cage traps are used for the harvest at the inlet channel although cast nets and scoop nets are also used for harvesting.

The environmental problems in the bheri system are: (i) floods and drought during culture operation; (ii) silting up of feeder canals and creeks; (iii) pollution of water sources through discharge of sewage effluent; and (iv) excessive growth of filamentous algae (Spirogyra sp.) and weeds causing problem of oxygen depletion due to decay in summer and production of noxious gases.

II. Orissa

Orissa State is endowed with a total estimated brackishwater resources of 31,600 ha, of which 22,958 ha (82% Government land) have so far been identified as suitable for development. These areas have no alternative economic use and devoid of mangrove vegetation, are spread over 7 estuarine zones and Chilka lagoon and over 4 coastal districts. The Space Application Centre (SAC) of the Indian Space Research Organisation (ISRO), Ahmedabad has prepared thematic maps of the coastal areas of Orissa (SAC/ISRO, 1992) based on satellite imagery to provide reliable information on mangrove forests, mudflats, sand beaches, tidal creeks, saline soils, agricultural lands, saline embankments etc. The ground verification of the maps has also been completed.

Orissa was the first State in the country to announce the land lease policy of the Government in 1981 for allotment of Government owned brackishwater lands for aquaculture. During 1983–84, the State launched a massive programme implementing a poverty alleviation scheme called “Economic Rehabilitation of Rural Poor” (ERRP) through shrimp culture in the Chilka Lake fringe areas. The scheme has enabled the landless poor each to get an average gross income of Rs 7,000 per annum from only 0.2 ha of pond developed by the Government and handed over to the poor.

The Orissa coast ranks second in the country (West Bengal being the first) with regard to natural P. monodon seed availability. The shrimp seed potential along the coastline has been estimated at 300 million, of which around 50% is P. monodon and 50% P. indicus. The exploitation of natural seed resources is of the order of 110 million per annum (85% P. monodon and 15% P. indicus), collected at 28 coastal centres where more than 1,900 local villagers (including women and children) are engaged as seed collectors. The seed trade is fairly well organised and, apart from meeting part of local demands within the State, the seed is also supplied to farmers in West Bengal and Andhra Pradesh.

There are certain unique features of shrimp culture systems developed in Orissa. The “confined pond” shrimp culture around Chilka Lake has small ponds of 0.2–0.5 ha waterspread area with a water depth ranging 0.8–1.2 m. The pond bottom is tilled, limed and manured initially. The ponds are filled by the seasonal monsoon rains in July-August and water turns brackish (15–18 ppt) by the leaching of salt from the pond soil. Stocking is done at the rate of 20,000–25,000 P. monodon seed per ha. Initially, feeding is with oilcake and rice bran mixture in wet dough and subsequently (week 2 onwards) with crushed land snail (Pila globosa) from the adjoining rice fields or mussel (Perna viridis) meat from the estuarine region of the lake as available. There is neither supply nor drainage of pond water. Harvest of the first crop is done during October-November with traps. Since evaporative loss of pond water is not compensated, the water level gradually comes down.

Water levels in some ponds at the end of the first crop permits stocking the ponds again for the second crop (winter crop), while in others the level is so low that they cannot be stocked again. The second crop harvest is done during February and the ponds become totally dry and remain so until the onset of the monsoon. Production rates reported are 430–625 kg/ha in the first crop and 300–450 kg/ha in the second crop.

The second system is the “confined Gheries” developed in the Chilka Lake fringe area. The “Sairat” fishing grounds which have all become defunct due to silting up have been converted into large size confined ponds of 2–50 ha area each by construction of embankments. The stocking is with wild P. monodon seed at the rate of 10,000–12,000 per ha. The stock grows on natural food available. Harvest is done after the monsoon is over with production from 200–250 kg/ha/year. Similar to the above, “tidal gheries” have been developed in the low lying coastal estuarine areas in Cuttack District, with production rates of 250–450 kg/ha/year. There is also another system of tidally fed ponds, with some of the farms using diesel pumps in addition to tidal intake. Modern shrimp farms are under development in the coastal districts of Balasore, Cuttack, Chilka and Ganjam. The results of a case study of semi-intensive farms at Paradeep, Orissa are given in Table 7. By the end of November 1990, the State had a total area of 6,151 ha under various types of shrimp culture: 1,945 ha of extensive ponds and 4,206 ha of extensive “gheri” culture.

Table 7. Case study: P. monodon culture at Paradeep, Orissa under DBT/MPEDA/ OSPARC project.

III. Andhra Pradesh

The estimated potential of brackishwater area in different coastal districts in Andhra Pradesh are shown in Table 8:

Table 8. Estimated potential for brackishwater aquaculture in Andhra Pradesh.

During 1989–90, the estimated area under shrimp culture was 3,430 ha, but by 1992–93, this figure had reached about 11,000 ha (Table 9). This is equivalent to a three-fold increase (320%) in a short span of about 3 years, the fastest growth rate recorded in the whole country. The Government is promoting a number of schemes for shrimp culture such as the SC Co-operative Finance Corporation Limited's farms at Nuvularevu and Srikumaram in Srikakulam District; at Gondayapalem and Davalampadu in Prakasam District; Fisheries (Shrimp) Estates at Krishnapatnam in Nellore District; Pollekurru Fisheries (Shrimp) Estate in East Godavari District; and at Kuntivenu in Krishna District. Also the District Rural Development Agency (DRDA) is implementing shrimp culture projects in Prakasam, Srikakulam and Krishna Districts.

Table 9. Shrimp culture in Andhra Pradesh, 1992–1993.

Shrimp farming methods adopted by farmers in Andhra Pradesh for P. monodon are shown in Table 10, as classified by MPEDA.

Table 10. Shrimp farming systems adopted in Andhra Pradesh.

* Natural feed refers to clam meat, trash fish, beef etc.

Feeding practices

Farmers adopting supplementary feeding practices use mixtures of oil cakes, rice bran, locally available snail, clam or mussel meat, and buffalo meat. Some examples of feed mixtures are shown in Table 11 (Wood et al., 1992). Towards the end of culture period, a low percentage of locally available dried trash fish may be added in the feed mixtures in an attempt to boost shrimp growth. Feed conversion ratios using these feeds are very variable even on the same shrimp farm. In some farms, FCR of 10 kg moist feed per kg of shrimp growth are commonplace, especially during periods of low salinity.

Table 11. Examples of feed mixes used in Andhra Pradesh.

Pollekurru Pond Environment: The average dissolved oxygen level of creek water has been steadily decreasing (from about 9 mg/l to 4–5 mg/l) over the last 10 years, which may be the result of the steady rise in the number of shrimp ponds becoming operational in this region of Andhra Pradesh. The ponds are drawing water from, and discharging pond drainage water to, the same supply creek. The increasing use of fertilisers and other agrochemicals on rice crops and the drainage of field water into the same creeks only adds to the problem. Pond pollution, as evidenced by the degree of blackness of the pond bottom mud, is most prominent in ponds using the powder-based, doughball and the local, moist feeds. The water stable pellet appears to produce little blackening of the mud, and thus, from a pollution prevention aspect, pelleting feeds would appear to be highly desirable.

Since the tidal amplitude of many of the supply creeks is low, and sedimentation rates are high (due to both natural processes and anthropogenic effects), the potential for adequate water exchange is steadily decreasing. Without improved pond planning, this problem will be compounded as the number of shrimp farms is increasing. This practice will be of major concern should shrimp disease outbreaks occur in a locality.

Nellore District
Nellore District has a coastline of 163 km and the major rivers flowing through the district to the Bay of Bengal are the Pennar, Swarnamukhi, Kandaleru, Pyderu, Chippaleru and Kalangi. The Buckingham Canal runs parallel to the coast and traverses the District. In view of these good water sources (fresh, brackish and seawater) coastal areas are subject to both extensive and intensive development of shrimp farming. The Buckingham Canal and the brackishwater creeks are used both for supply and for drainage of aquaculture farms that have come up along both sides of their banks. Some of the large farms use seawater pumped into the ponds. This district has the highest concentration of shrimp farms. Both extensive and semi-intensive farming practices are followed (Tables 12 and 13).

Table 12. Case Study: Semi-intensive shrimp farming by TASPARC/MPEDA/DBT project at Nellore.