U Minn Thame, Department of Fisheries, Yangon.
Fish for sale at a market in Yangon, Myanmar.
This paper highlights the present status of aquaculture and sound management of aquaculture development in Myanmar. Severe impacts are rarely found in Myanmar, either in the environment or in aquaculture, but the detrimental effects of waste discharges to natural waterbodies needs to be investigated. Existing legislation and regulations are reviewed in order to render a better understanding of Government policy towards development of the aquaculture industry, maintenance of natural resources and protection of the environment.
The fisheries sector is very important to the economy of Myanmar as fish constitute a major source of animal protein in the diet of the people. It is the fourth largest source of foreign exchange earnings after timber, minerals (including jewels) and rice. The country is also endowed with rich and varied inland and marine fishery resources.
3. STATUS OF AQUACULTURE
3.1 Aquaculture production.
Aquaculture production in Myanmar between 1987 and 1993 is shown in Table 1.
Map of Myanmar.
Table 1. Aquaculture production in Myanmar, 1987–1993.
|Total production (tonnes)||5,493||5,673||6,947||7,087||25,963||53,723||64,501|
|Value (000 US $)||9,171||12,914||20,784||27,974||nd||nd||nd|
|Production as % of GNP||nd||nd||nd||nd||nd||nd||nd|
Source: Ministry of National Planning and Economic Development, 1994.
(nd = no data)
There is enormous development potential for the aquaculture industry in Myanmar, in terms of Government support and the resources available. There are also substantial areas available for aquaculture development, as indicated below.
3.2 Inland and coastal resources
Inland and coastal water resources of Myanmar are shown in Table 2 and the areas with potential for aquaculture development are shown in Table 3.
Table 2. Inland and coastal water resources of Myanmar.
|Freshwater lakes and reservoirs||59,130 ha|
|Rivers and streams||4,684 km|
Table 3. Inland and coastal aquaculture potential in Myanmar.
|Inland (Freshwater)||288,230 ha|
|Swamp and mangrove||520,000 ha|
3.3 Existing aquaculture practices in Myanmar
Freshwater aquaculture is rather more developed than brackishwater and marine aquaculture in Myanmar. In inland aquaculture, Indian carps are the dominant species cultured in ponds. Prawn and shrimp farming is still at the experimental stage. A list of the cultured fish species and culture systems are shown in Table 4, together with the production and value of each species.
Table 4. Species cultured, culture systems, production and value of aquaculture in Myanmar.
|Species Cultured||Culture System||Quantity|
|pond||3||nd||Domestic + Export|
|pond||1||nd||Domestic + Export|
After the promulgation of the Law Relating to Aquaculture, the list of existing fish ponds was surveyed and it amounted to 32,425 inland fish ponds covering an area of 24,468 ha in 1990. However, the list of fish ponds officially submitted to the Government indicated 22,294 ha of fish ponds in 1990. The official figure is different because it is quoted according to registered figures for the collection of aquaculture revenue. Precise figures of fish pond acreage will hopefully be established in the next 2–3 years. At present, existing shrimp ponds amount to 8,114 ha.
3.4 Supply of inputs in the development of the aquaculture industry
Freshwater aquaculture commenced in 1954 with tilapia and common carp. It was moderately progressive in 1977, after the successful hypophysation of Indian carps (especially Labeo rohita), but progress was slow until 1989 due to legal constraints on land utilisation. In 1989, the State Law and Order Restoration Council enacted the Law Relating to Aquaculture and illegally existing fish ponds became legal under the law. Indian and Chinese carps were still the predominant culture species, cultured by means of semi-extensive to semi-intensive methods with polyculture or composite systems. A suitable combination of different fish species was polycultured in order to fully utilise all food niches in the pond.
The Department of Fisheries, with its 22 fish seed production stations, produced more than 25 million fish seed in 1992. In addition, several private fish farmers operate their own hatcheries and produce carp and catfish seeds to meet demand. Prawn and shrimp culture have begun to gain popularity among fish farmers, but remain in the experimental stage due to technical and economic contraints. Recently, there has been interest in implementing shrimp hatcheries by private farmers, including joint ventures and private companies. To be in line with the market economy, the Government has leased out fallow lands with 30 year grants, for use by the aquaculture industry. One significant input is that legal fish farmers have the opportunity to obtain financial support from the Myanmar Agriculture and Rural Development Bank at a reasonable rate of interest. Some foreign joint-venture companies have introduced feed mills and produced pelleted feed with prescribed formulas, others import feed pellets, antibiotics and equipment relating to aquaculture. The Government has highlighted the development of the prawn and shrimp aquaculture industry, so that the industry can grow rapidly in the future.
With respect to mariculture, the culture of grouper (Epinephelus sp.) and spiny lobster (Panulirus sp.) is under experimentation at Tanintharyee Division, in net cages by the private sector. The artificial propagation of these species has not been successful and thus the availability of seed is dependant on wild stocks. Although formulated feed pellets are imported to feed these marine species, trash fish remains the major source of feed. At the moment, all aquatic products are allowed to be exported.
3.5 Legal framework
3.5.1 Access to aquaculture operations
Definition of aquaculture
Aquaculture is defined as the farming of fish (as defined in the law) in the natural waters or man-made confined waters; the propagation or collection of wild stocks for the purpose of growing at least one stage of the fish life through various culture systems; and techniques to sustain profit or social benefit.
Aquaculture laws and regulations
In 1989, the Myanmar Government promulgated the Law Relating to Aquaculture. Its functions are as follows:
Demarcation, allocation and administration of lands and water for aquaculture;
Granting leases and issuing licences for aquaculture;
Monitoring and inspecting aquaculture enterprises;
Taking legal action against any person who contravenes the law.
There is a system of licensing to control the development of aquaculture, which is operated by the Department of Fisheries.
Special consent system
There are codes of practice for the utilisation of lakes, rivers and coastal areas for aquaculture. No codes of practice exist for mangrove areas.
3.5.2 Environmental management of aquaculture
Water quality and water pollution control
There is no legislation dealing with water quality controls in aquaculture or of effluent from farms.
Environmental impact assessment
No formal EIA is carried out prior to the development of aquaculture farms.
Control of the movement of fish
Legislation for live fish export and import has recently been promulgated. In the meantime, according to the declaration by the Government, only marine aquatic products are allowed to be exported. This means the freshwater aquatic products have to be consumed within Myanmar, in order to maintain sufficient fish consumption in the country. Fish and fish products from aquaculture are, however, allowed to be exported.
Control of toxic or hazardous substances or pharmaceutical preparations
There are no codes of practice for the use of such biocides.
Control of pesticides
Pesticides Law No 10/90 (11 May 1990) Chapter 13, Section 35. No person shall use pesticides except for the purpose of preventing the danger of an outbreak. There is no control of pests in crops, foodstuffs or beverages destined for immediate consumption by the public. In addition, no person shall use pesticides to catch or kill terrestrial or aquatic animals.
Major protected areas are pasture land, paddy farms and forest lands. However, to legally excavate a fish pond, the farmer must have special permission according to Land Utilisation Act Number 39. With respect to natural waterbodies, recreation places and navigational waterways, aquaculture development is not allowed.
Protection of indigenous species
As a means of protecting indigenous species, the capture or collection of spawners, fry and fingerlings is prohibited during the spawning season (May to September) by the Law Relating to Freshwater Fisheries Act 5 Section 22, Subsection (c) and legal action is taken against any person who contravenes the law. Without special permission issued by the Department of Fisheries, the capture or collection of berried females and post-larvae of freshwater prawn and marine shrimp is prohibited, in order to enrich valued species in natural waters.
Fish Health Certificates are being issued to exporters based on visual inspection of fish for signs of gross pathology and microscopic examination for ectoparasites. Live-fish importers must have special permission from the Department of Fisheries after monitoring and inspecting quarantine certificates and the fish.
Product quality control
Measures regarding quality control of aquaculture and capture fisheries products is conducted by the Myanmar Fishery Enterprise which has laboratories and equipment concerning quality control.
3.5.3 Institutional framework
|Department of Fisheries.||1.||Development of the aquaculture industry.|
|2.||Research activities relating to aquaculture.|
|3.||Technology transfer to fish farmers through extension.|
|4.||Technical services and consultancy to the industry.|
|5.||Conservation of aquatic resources.|
|6.||Collection of fishery revenue.|
|Governing environmental issues|
|Department of Fisheries.||1.||Implementing management and conservation of living aquatic resources.|
|2.||Advising Government on the rational exploitation of living aquatic resources.|
|3.||Providing legal advice to the Ministry on matters relating to Fisheries Laws of the Seas.|
|4.||Compilation of fisheries statistics.|
|5.||Undertaking appropriate research, training and fisheries development.|
|National Commission for Environmental Affairs.||Responsible for national environmental policies, planning and regulations, but not involved in aquaculture.|
3.6 Myanmar government policy towards aquaculture development
The government of the State Law and Order Restoration Council (SLORC) never hesitates to solve legal constraints when it is confronted or required to reform at national level. Very recently, the chairman of SLORC produced guidelines to upgrade and expand the shrimp culture industry to up to 40,000 ha in coastal regions. The targeted shrimp pond areas shall be fully developed, phase by phase, by 1996. Measures on feed and seed requirements are monitored and evaluated. The development of shrimp farming is to be intensified with the inputs of advanced technology, which will be followed up by the implementation of feed mills and shrimp hatcheries.
Regarding financial support by the Government, Myanmar Agriculture and Rural Development Bank lends the aquafarmers Kyats 20,000 per acre (Kyats 50,000 per hectare) for operational expenses and 50 % of the total investment on construction of aquafarms in the second year.
4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW
Aquaculture development in Myanmar has, until recently, been fairly limited. Freshwater finfish culture, particularly of the Indian major carps and Chinese carps, is more advanced than other forms of aquaculture, but there is considerable scope for further development. Many potential resources of culturable areas exist among the large areas of inundated wastelands, backwaters, tidal estuaries, lagoons and swamps. It is anticipated that the industry will expand and gain momentum in accordance with the Government's market-oriented policy. Although no significant impacts of aquaculture on the environment have yet been recorded, there is a need to formulate a long-term plan for assessing and managing the environment in balanced relation to aquaculture development.
4.1 Impacts of the external environment on aquaculture production
4.1.1 Inland aquaculture
Problems relating to seasonal flooding, water availability, pond drought due to high evaporation and siltation are major physical problems normally encountered by fish farms.
Toxic industrial wastes
There have been no reports of industrial pollution at fish farms.
Human and agricultural wastes
The overall usage of fertilisers, insecticides and pesticides is low and has not caused problems to inland aquaculture.
There have been no reports of oilspills affecting aquaculture.
There are no dangers of this nature in Myanmar.
4.1.2 Coastal aquaculture
Coastal aquaculture is at present fairly undeveloped and there are no records of any impacts of the external environment on shrimp farming or any other coastal aquaculture activity. In addition, no red tides have been reported along the coast of Myanmar.
4.2 Contamination of aquaculture products
There have been no reports of paralytic shellfish poisoning or toxic residues in fishery products.
4.3 Impacts of aquaculture on the environment
Only semi-intensive aquaculture practices are common and no impacts due to residual feed wastes discharged into natural waters are found. However, of the 4,000 leasable fisheries that existed in 1970 some have deteriorated and the number has decreased to about 3,700. One of the many reasons for this deterioration was the expansion of fish ponds.
4.3.1 Inland aquaculture - finfish
Some finfish farms, more intensive farms in particular, have resulted in sedimentation, reduced water flow and land subsidence. These problems might become more important in the near future.
There has been no use of chemo-therapeutants for disease control or pond treatments and so there are no effects of chemicals on the external environment.
It is anticipated that finfish farms and hatcheries will result in the release of nutrients and micro-organisms and eutrophication.
Interactions between aquaculture and native species
Inland fish farming may have various effects that reduce the productivity and diversity of native fish stocks. Of particular concern is the African giant catfish (Clarias gariepinus) that was introduced to Myanmar for hybridisation with the Asian species (C. macrocephalus). There are worries that it may establish itself in natural waters and have a detrimental effect on indigenous fish stocks.
There are fears that all forms of aquaculture will result in reduced stocks of seed, so the exploitation of wild seed is restricted as a means of maintaining natural populations. It is expected that production from hatcheries will have an increasingly important role in enhancing the productivity and diversity of wild fish stocks. The spread of disease between wild and cultured fish is a source of concern in Myanmar. In the past, outbreaks of epizootic ulcerative syndrome (EUS) in wild fish has caused severe losses in cultured Indian major carps.
Social conflict and aquaculture
There is some conflict between aquaculturalists (extensive pond farmers in particular) and agriculturalists, domestic users, other aquafarmers and artisinal fishermen. There is competition for land, water space and inputs such as feed, fertiliser and seed. These problems are expected to become more severe as aquaculture continues to develop. In 1990, the State Law and Order Restoration Council enacted a law recognising farms established before 31 March 1990, in order to reduce conflicts with agricultural or forestry sectors.
4.3.2 Inland aquaculture - crustacea
Sedimentation and reduced water flow due to freshwater prawn farms are problems that are expected to increase in the future.
4.3.3 Coastal aquaculture - crustacea
As shrimp farming in Myanmar is still in the developmental stage, coastal aquaculture has not had a significant impact on the environment. Myanmar has large areas of mangrove forest along its coastline, but aquaculture has not had a significant impact on these forests.
Most shrimp culture is in Rakhine State and uses wild caught post-larvae for stocking. Over exploitation of natural stocks is considered to be a major constraint to the development of the industry and so joint ventures between the Department of Fisheries, Myanmar Fisheries Enterprise and the private sectors are planned to establish shrimp hatcheries to supply the farms and conserve natural stocks.
There are some localised disputes between shrimp, finfish and seaweed farmers and agriculturists, domestic users, other aquafarmers and artisinal fishermen, but this has been reduced by legislation passed by the Government allocating land for aquaculture use.
5. No in-depth study of aquaculture in Myanmar was carried out.
6. PRIORITIES FOR DEALING WITH ENVIRONMENTAL PROBLEMS
6.1 Prevention and cure of the detrimental effects to aquaculture and man-made changes to the environment
The development of the aquaculture industry is gaining momentum in Myanmar. Implementation of freshwater and marine hatcheries is taken into consideration by the Government and the private sector. The Department of Fisheries, although significant impacts of aquaculture on the environment have not been found, is monitoring water quality and the detrimental effects of hatchery effluent and waste discharges to natural water bodies.
6.2 Prevention and cure of the detrimental effects of environmental changes caused by aquaculture activities
Water quality deterioration due to over feeding, over stocking and a lack of water exchange may constrain the development of the fish farming industry. These factors are due to a lack of knowledge of sound management techniques and consequently the Department of Fisheries has launched extension activities to give farmers access to such information.
The exploitation of natural fish stocks for seeding fish farms is a problem, particularly in the case of coastal shrimp farming in Rakhine State. Therefore, the Department of Fisheries is planning to establish hatcheries for post-larvae production to prevent severe depletion of wild stocks.
Ministry of National Planning and Economic Development, 1994. The Union of Myanmar Review of Financial, Economic and Social Conditions for 1993/94.
G.B.N. Pradhan and M.B. Pantha, Fisheries Development Division, Department of Agriculture Development, Kathmandu.
Extensive cage culture in the Pokhara lakes, Nepal.
Fish symbolise good omens in Nepal and they are also acceptable foods for all non-vegetarians in the country. Despite its auspicious character and prominent dietary contribution, the per caput consumption of fish is rather low. Fish production in Nepal is restricted to inland capture fisheries and aquaculture because of the countries land-locked nature. Aquaculture has great potential in Nepal because there is ample opportunity for the expansion of culture areas and yields can be substantially increased by improved technology and management. Moreover, aquaculture is important in view of its utility as a source of protein and in generating income and employment, as well as its role in promoting a more ecologically balanced use of land and water resources. His Majesty's Government of Nepal has given a high priority to the proper development of aquaculture in the country. By the year 2000 AD, per caput fish consumption is targeted to increase by 2 kg from the present level of about 800 g. Fish production is targeted to reach 50,000 tonnes by the end of the century, which means nearly four times the present production level is required. To achieve these goals, expansion and intensification of fish culture is required in Nepal.
Aquaculture interacts with the environment -- it utilises resources and causes environmental change. Although there have been significant socio-economic benefits arising from the expansion of aquaculture, it may increasingly be subject to a range of environmental, resource and market constraints. Aquaculture is seen to compete for land and water resources, which in some cases come into conflict with other resource users. The development of the aquaculture industry in Nepal is being obstructed by growing environmental problems which arise from the effects of massive deforestation as well as unplanned urbanisation and industrialisation, and result in drought, floods, soil erosion, sedimentation and pollution. Such problems naturally exert a corresponding impact on the aquaculture industry. The intensity of production and capital losses, magnitude of disease outbreaks and product contamination related to environmental problems have yet to be properly assessed with respect to their effect on the long term viability and sustainability of the industry. This is now an area in urgent need of study. While few cases have been reported where aquaculture has had a positive or negative impact on the environment, a thorough study has not yet been made. In view of the implications for the feasibility and sustainability of the industry, these issues have to be urgently addressed.
Map of the Kingdom of Nepal.
The only non-vegetarian food commonly acceptable to all non-vegetarians is fish. Culturally also, fish is considered to be auspicious by the Nepalese people as fish symbolise good omens on all occasions in Nepal. Despite its auspicious character and prominent dietary contribution, its per caput consumption is rather low. The reasons for the low consumption are: firstly, fish production in Nepal is restricted to inland capture fisheries and aquaculture because of the country's land-locked nature; secondly, fish is still an expensive commodity; and thirdly, aquaculture development represents a largely untapped resource in Nepal. There is, however, ample opportunity for the expansion of culture areas and yields can be substantially increased by improved technology and management. However, in view of its utility in providing protein food and income generating employment opportunities as well as its role in promoting a more ecologically balanced use of land and water resources, the importance of its development is obvious. Furthermore, there is great potential for the development of aquaculture in many areas of Nepal.
Aquaculture interacts with the environment. It utilises resources and causes environmental change. Although there have been significant socio-economic benefits arising from the expansion of aquaculture, it is increasingly subject to a range of environmental, resource and market constraints. Aquaculture is seen to compete for land and water resources, which in some cases come into conflict with other resource users. The development of the aquaculture industry in Nepal is being obstructed by growing environmental problems. These problems arise from the effects of massive deforestation as well as unplanned urbanisation and industrialisation, which results in drought, floods, soil erosion, sedimentation and pollution. Such problems naturally exert a corresponding impact on the aquaculture industry. However, the intensity of production and capital losses, magnitude of disease outbreaks and product contamination related to environmental problems have yet to be properly assessed with respect to their effect on long term viability and sustainability. There is now an urgent need for study. While a few cases have been reported where aquaculture has had positive or negative impacts on the environment, a through study has not yet been made. In view of its implications for the feasibility and sustainability of the industry, environmental issues now have to be urgently addressed. This is not only the case in Nepal, but in most other countries of the Asia-Pacific region. There is now good evidence that production losses, product contamination and disease outbreaks, which are all related to environmental deterioration, pose a major threat to the long term viability and sustainability of aquaculture in all countries of Asia. Moreover, some serious cases of conflicts have been observed between aquafarmers and other aquatic resource users, which have highlighted major deficiencies in planning, monitoring and control strategies in the field of aquaculture in the region.
The purpose of this national study is to provide baseline information on aquaculture and environment in Nepal and prepare a regional collaborative action plan. This report therefore focuses on the role and status of the aquaculture industry in Nepal, with special emphasis on legal and institutional framework and a general review of interactions between aquaculture and the environment. The study also includes important aspects like priorities for dealing with environmental problems, and future aquaculture development and recommendations. It also includes an in-depth study of the interactions between aquaculture and environment with special reference to pond culture of carps and carp cage culture in lakes of the Pokhara Valley in Nepal. Pond culture of carps is a pioneering aquaculture practice in Nepal, which has emerged as a very viable and popular activity in the terai and inner-terai districts of the country. In Nepal, cage culture of carps is considered a major step towards the utilisation of natural water fisheries management for increased production.
3. STATUS OF AQUACULTURE
3.1 Aquatic resources in Nepal
There are three major river systems in Nepal (Koshi, Gandaski and Karnali). These rivers are fed by hundreds of small rivers originating in the snow-capped Himalayan mountains in the Mahabharat and Siwalik mountain regions. Rivers in Nepal cover an estimated area of 395,000 ha. Similarly, a number of small to medium-sized lakes in various parts of the country cover 5,000 ha and about 1,500 ha of small reservoirs have been constructed in the country. In addition, there is a considerable amount of surface area present in village ponds (around 6,500 ha) and irrigated paddy fields covering about 325,000 ha (FDD, 1993). The growth of hydroelectric power stations and irrigation projects will add more water bodies in years to come. A feasibility study on the various river basins and systems indicates an addition of about 78,000 ha of reservoirs on their completion (FDD, 1993). Collectively, these water bodies cover nearly 3 % of Nepal's land area. It is estimated that some 500,000 ha of water surface may be available to fish production, of which approximately 100,000 ha would be lakes, reservoirs and village ponds (NARC, 1991/92). The existing water resources of the country and their future potential reveal that there is tremendous scope for expansion and intensification of fish production in the country (Table 1).
Table 1. Estimated water surface area in Nepal (FDD, 1993).
|Resource details||Estimated area|
|Irrigated rice fields||325,000||43.6||-|
3.2 Aquaculture in Nepal
Agriculture is recognised as one of the most important sectors in development planning of in Nepal and, as such, has been given the highest priority by His Majesty's Government (HMG). Under this sector, fisheries has emerged as a small, but potentially important area. Presently, fisheries account for about 1.5% of the agriculture share of GDP. Although the relative economic importance of fisheries is low at the moment, the potential for increased production through culture-based activities is good. Aquaculture represents a large untapped resource in Nepal. There is ample opportunity for the expansion of culture areas and, with improved technology and efficient management, yields can be substantially increased. HMG of Nepal has given a high priority for development in view of its utility in providing protein and income-generating employment opportunities. Aquaculture also promotes a more ecologically balanced use of land and water resources and is a valuable sector of the agricultural economy.
By the year 2,000, per caput fish consumption is targeted to increase to 2 kg from the present levels of around 800g (FDD, 1993). Fish production is targeted to reach 50,000 tonnes by the end of the century, which is nearly four times the present production level. To achieve these goals, intensive fish pond culture has to be developed. Aquaculture production reached 8,419 tonnes in 1992/93 (about 57%) in a total fisheries production of 14,775 tonnes in Nepal (Table 2).
Table 2. Aquaculture production in Nepal.
|Total production (tonnes)||10,717||12,100||12,522||14,547||15,595||16,516||14,775|
|Capture fisheries (tonnes)||5,711||5,661||5,601||5,561||5,576||7,115||6,356|
Rivers and lakes
|Aquaculture production (tonnes)||4,939||6,364||6,845||8,906||9,935||9,340||8,364|
|Public sector (tonnes)||67||75||76||80||84||61||55|
|Value (US $ 000s)||nd||nd||nd||nd||nd||19,752||20,634|
|Contribution to GDP (%)|
nd = no data.
The contribution of aquaculture to national Gross Domestic Product (GDP) has been estimated at 0.4%, while it accounts for about 0.8% of Agriculture Gross Domestic Product (AGDP) in the nation (Table 3). The aquaculture production programme commenced in 1981/82 with the execution of the Aquaculture Development Project. The areas devoted to aquaculture are shown in Table 4.
Table 3. Contribution of aquaculture and fisheries in GDP in Nepal 1992/1993 (in millions).
|Particulars||Nepalese Rupees||US $||Contribution to National|
|Contribution to Agriculture|
2. Other Agriculture
Presently, seven species of commercially valuable carps are being cultured in Nepal. These include three indigenous species: rohu (Labeo rohita), naini (Cirrhinus mrigala) and bhakur (Catla catla) and four exotic species: common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), bighead carp (Hypophthalmichthys nobilis) and grass carp (Ctenopharyngodon idella).
Table 4. Aquaculture coverage in Nepal.
|Pond fish culture (ha)||944||4,070||4,179||4,507||4,843||5,184||4,664||4,593|
|Rice fish culture (ha)||-||-||20||46||52||42||43||56|
|Cage culture (m3)||3,748||13,840||16,857||18,357||12,850||13,364||9,125||10,639|
|Enclosure culture (ha)||-||-||-||7||8||13||7||4.4|
Culture systems and culture methods
In Nepal, major aquaculture systems being adopted are: carp in polyculture ponds; carp polyculture in lake enclosures; cage culture of herbivorous carp species (major species: silver carp and bighead carp), and common carp in rice-fish culture. A change from extensive systems to semi-intensive/intensive farming methods is currently occurring in all aquaculture systems in the country. The majority of carp polyculture ponds are located along the southern belt (terai and inner-terai) of Nepal because of warm climatic conditions in these areas. The cage culture and enclosure farms are located exclusively in the mid-hill regions of the kingdom (Figure 1).
Species quantity, value and employment
The summary of species quantity, their production and value under different aquaculture practices in Nepal shows that silver carp and bighead carp contribute a major share, about 45% (Table 5). Common carp and indigenous major carp contribute about 24% and grass carp contribute only about 5% only of total cultured fish production in Nepal.
Figure 1: Fisheries activities in Nepal.
Table 5. Summary of species quantity and their production and value under different aquaculture systems in Nepal, 1992/1993.
|Common carp||Silver carp||Grass carp||Bighead carp||Rohu||Naini/Bhakur|
|Pond culture||Production (tonnes)||2,067||2,480||413||1,240||-||2,067|
|Value (US $ 000s)||2,715||2.757||542.5||1,378||-||3,134|
|Rice-fish culture||Production (tonnes)||17||-||-||-||-||-|
|Value (US $ 000s)||22.3||-||-||-||-||-|
|Other (Extensive)||Production (tonnes)||4.0||3.0||3.0||3.0||7.0|
|Value (US $ 000s)||5.25||3.33||3.94||3.33||10.61|
|Cage culture||Production (tonnes)||-||28.0||8.0||20.0||-||-|
|Value (US $ 000s)||-||31.12||10.51||22.23||-||-|
|Enclosure fish culture||Production (tonnes)||2.0||3.0||1.0||2.0||1.0|
|Value (US $ 000s)||2.63||3.33||1.31||2.22||1.52|
|Open stocking in lakes||Production (tonnes)||13.0||15.0||3.0||7.0||12.0||-|
|Value (US $ 000s)||19.7||19.7||4.55||9.20||20.6||-|
|AQUACULTURE||Value (US $ 000s)||2,765.3||2,814||562.9||1,415.3||3,165.8||3,134|
Table 6 shows similar data from capture fisheries, the main species caught being sahar (Tor sp.), katle (Accroscohiellus sp.), asla (Schizothorax sp.) and other local species.
Table 6. Production from capture fisheries in Nepal 1992/93.
|Capture Fisheries||Freshwater Fish|
|1.||Rivers and Lakes|
Value (US $ 000s)
Value (US $ 000s)
|Value (US $ 000s)||9,981.1|
In Nepal, it has been estimated that about 12,240 families are engaged in aquaculture activities and about 36,700 people have been estimated to be actively involved in this profession. About 61,700–73,500 people are estimated to be direct beneficiaries from aquaculture (Table 7).
Table 7. Estimates of people involved in fisheries and aquaculture in Nepal, 1992/93.
|People Involved||Number of direct beneficiaries|
|Active member||No of family|
|4,593||8,215||35,000||11,500||58,000 – 69,000|
|56||17||400||190||950 – 1,100|
|10,639||53.2||400||215||1,100 – 1,300|
|4.4||8.8||40||10||50 – 60|
Open water stocking
|-||50||500||125||600 – 800|
Rivers and lakes
|(Marketing, storage, equipment, transport etc.)|
Supply of inputs
The successful propagation of cultivated and indigenous fish species and a reliable supply of their seed, is a major breakthrough in the development of aquaculture in Nepal. The total number of fish seed supplied reached about 51.6 million in 1992/93, where the private sector contributed 39.1 million (about 76%) and the public sector contributed 12.6 million (about 24%). The details of fish seed supply and estimated supply for future activities are given in Table 8.
Table 8. Details of fish seed supply and distribution in Nepal 1992/93.
|Common name||Scientific name||Number of seed|
|Carps||common carp||Cyprinus carpio||17,939.3|
|silver carp||H. molitrix|
|grass carp||C. idella||20,502|
|big-head carp||A. nobilis|
|Other local species||sahar||Tor sp.|
|Total seed supply||51,655.0|
3.3 Legal framework
3.3.1 Access to aquaculture operations
Definition of aquaculture
Fisheries activities are split by policy guidelines into inland aquaculture and natural water fisheries. Aquaculture involves all activities where complete and partial control of the fish production cycle is undertaken. Further, the policy guidelines split aquaculture into:
Cage and pen culture;
Production of seed for stocking in natural waters.
Legislation applicable to aquaculture
The Aquatic Life and Aquatic Resources Conservation and Utilisation Act will replace the now defunct Aquatic Life Conservation Act 2017 B.S. The new legislation (to be tabled in Parliament in July 1994) includes regulations for fisheries and aquaculture management. The following areas receive attention under this new act:
Definition of the act;
Control of illegal fishing;
Authority of local government units;
Protection of endangered species;
Utilisation and leasing of water bodies;
Peoples rights in relation to aquatic resources;
Responsibility of other agencies to consider aquatic life;
Delegation of authority to lowest “grass root” level and community participation;
Following this act, laws and regulations will be formulated for implementation.
This system may be explained as follows:
All aquaculture farms are requested to be certified as aquaculture farmers and register with the District Agricultural Office (under the Department of Agriculture Development (DOAD) Directives). Registration is required by the Government to monitor the development of aquaculture in the country.
In practice, most aquaculture farms are certified, but not all are registered at present. Aquaculture projects which have a credit component (disbursed through the banks) must be certified to obtain financial support from the bank and technical support from the DOAD. The Fisheries Units of the district level DOAD make a technical appraisal of the project before the certificate is issued.
Cage farms also require a fisheries certificate. The fisheries certificate in future will also be provided by the district DOAD Office. The application has to come through a private Fishery Community organisation. This organisation has the sole responsibility for cage culture on each lake/reservoir. The present practice is for fisheries certificates to be provided by the Fisheries Development Division and issued if water quality and other environmental parameters are not suitable.
Site selection criteria have been developed for fish pond culture and cage culture. These criteria include environmental considerations (e.g. vulnerability to flooding and suitable water quality for pond fish culture). The criteria are included in Extension Directives prepared by the Fisheries Development Division and issued by the DOAD for use by farmers.
3.3.2 Environmental management of aquaculture development
Water quality and pollution control
There is no legislation for control of effluents discharged by aquaculture. Suitable water quality criteria in aquaculture water supplies are given in Extension Directives. Fisheries Certificates are not issued if water quality and other environmental parameters are unsuitable. There is no legislation providing for ambient water quality standards. No agency has responsibility for monitoring of water quality in Nepal, although this activity is undertaken by several Government Departments, including the Fisheries Development Division, which has responsibility for water quality in fisheries and aquaculture environments. Some NGOs are also involved in measuring water quality for scientific purposes.
New laws and regulations in this regard will be formulated under the proposed Act.
Environmental Impact Assessment
There is no legal requirement for formal EIA to be carried out for aquaculture in Nepal. Formal EIA may be required in future for aquaculture development (although the scope of this has to be decided). Environmental issues are considered in site selection and planning of aquaculture developments.
Control of movement of fish
Procedures/rules for the introduction or transfers of freshwater fish. There are no controls over the movement of fish from India to Nepal due to the open border. Fish imported under Government programmes require health certificates. The Fisheries Development Division is working on a set of guidelines for quarantine/introductions. Aquarium fish are also imported from India, Thailand, Hong Kong and Singapore without any health certification.
Control of chemicals
There are no laws governing the use of chemotherapeutants for fish. However, there is an Extension Directive concerning “Fish Poisoning as a Management Tool”.
Within National Parks, aquaculture and other forms of development are not usually allowed, unless the activity is for conservation. Discussions are being held for fisheries development to enhance populations of local fish species in some National Parks.
Protection of endangered species
Under the new Act, a special article for endangered fish species is designed to control illegal exploitation of endangered fish species. The fish which are endangered remain to be identified.
There are no laws or regulations which require the quarantining of imported live fish. Consequently, fish pathogens may enter Nepal by air or land. Since 1989, outbreaks of epizootic ulcerative syndrome (EUS) have occurred in many districts, and imports of live fish are now visually examined at quarantine offices in border areas, and at the International Airport. However, because of the open border with India, it is difficult to check the entry of all fish seed over the entire border area. The Fisheries Development Division has warned farmers not to stock imported fish seed that have not been certified disease free and instructed hatcheries to arrange treatment before distribution of fingerlings if the disease appears. Fish health management is included in Extension Directives under basic aquaculture management advice.
Product quality control
Standards of weight, size and freshness exist that apply to all products from pond or cage cultured fish and fish from stock enhanced lakes. These are not, however, legal standards. The Fisheries Development Division of the Department of Agriculture undertake some monitoring of product quality, but there is no agency responsible for the enforcement. The Municipality are being requested to monitor and maintain standards for fish quality in local markets.
3.3.3 Compliance control and related problems and difficulties
The authority to implement laws and ensure compliance was not identified in earlier legislation. This issue is under consideration in the proposed Act.
3.4 Institutional framework
The institutions involved in aquaculture development and their major functions related to development, research and environmental issues in Nepal are given below:
|1.||Ministry of Agriculture, Department of Agriculture and Fisheries Development Division.||Policy planning, programme implementation, monitoring and evaluation, training and extension.|
|2.||Nepal Agriculture Research Council.||Research in the agriculture sector, including aquaculture research.|
|3.||National Aquaculture Research Programme.||Aquaculture research and training.|
|4.||Royal Nepal Academy for Science and Technology.||Scientific Research.|
|5.||Tribhuvan University.||Scientific Research.|
|6.||Institute of Agriculture and Animal Science.||Scientific Research.|
|1.||Environment Protection Council.||Policy guidelines and directives in managing environment in the context of resource conservation and development. Formulation of plans and policies for environmental conservation and protection and co-ordination of environmental programmes.|
|2.||National Planning Commission, Environment Division.||National environment policy, planning and regulations, including aquaculture.|
4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW
4.1 Impacts of the external environment on aquaculture
The development of aquaculture and fisheries in Nepal is being obstructed by growing environmental problems. These problems arise from the effects of massive deforestation and unplanned urbanisation and industrialisation, resulting in drought, floods, soil erosion, sedimentation, siltation and water pollution. Environmental problems will naturally exercise a corresponding impact on the aquaculture industry. Although environment-related problems have not yet been properly assessed for aquaculture, they are considered to be important components in the sustainable development of the industry in Nepal. At present, aquaculture development is still of low intensity and as such, only a few cases of environmental problems have been reported.
Flooding is a problem in low-lying areas during monsoon periods and causes physical destruction of ponds as well as loss of stock. The ponds in the terai and inner terai districts suffer from physical changes (such as flooding and heavy siltation) during monsoons and drought during the dry season, both of which may lead to production losses and physical damage. The development of rice-fish culture has declined due to some farmers suffering the impacts of environmental problems, such as maintenance of water level in the flood season, destruction of physical structures from soil erosion and loss of production.
The construction of irrigation dams and diversion of rivers for power generation have caused adverse impacts on river ecosystems and migrating indigenous fish stocks, reducing the potential for further increases in fisheries production. So far, little attention has been given to the impacts of such activities on fisheries.
Large scale deforestation, mining and road construction in hilly areas are important environmental concerns in Nepal, leading to soil erosion and landslides. The forest area coverage in 1964 was about 6.4 million ha, which has decreased by 0.1 million ha, reaching 6.3 million ha in 1986. Such problems lead to silt-laden waters in rivers and lakes, which are potentially the most important resource for increased fish production in Nepal. However, the impacts of environmental problems encountered have hampered fisheries development activities in river systems. High siltation due to deforestation and soil erosion appears to have damaged the breeding areas of important fish species, thus endangering their existence.
Problems related to the impact of sedimentation are also extremely difficult to control. Minimisation of the extent of damage will require adequate measures to be taken by the concerned agency. Few articles are included in the Aquatic Life and Resources Conservation Act in which stock replacement of commercially important indigenous fish species is visualised. Siltation is an acute problem over many areas of the Kingdom and is expected to continue to be so in the foreseeable future.
As a result of massive deforestation activity in lake catchments and heavy rain during the monsoons, there have been several landslides and soil erosion. The surface runoff from these areas carry enormous amounts of silt and organic wastes into lakes and reservoirs. Siltation problems are particularly acute in Lakes Phewa and Rupa in the Pokhara Valley. Heavy silt loadings during monsoons have caused serious sedimentation problems in the Indrasarobar hydroelectric reservoir. The practice of intensive potato farming in the surrounding terraced land has further intensified the problem by depositing large amounts of top-soil into the reservoir. Such problems have greatly affected the ecology of the reservoir for aquaculture and fisheries activities. Increased sedimentation in the reservoir will also be detrimental to power generation in the long run. A sudden heavy rainfall in August 1993 around the catchment area of Indrasarobar reservoir, and sudden rise of water level up to 22 meters in a night, led to the total destruction of public and private cages.
Although industrialisation is in its infancy in the Kingdom of Nepal, localised water pollution from the discharge of toxic industrial waste is reported around Kathmandu. The situation is not being monitored by any specific agency.
Agricultural and domestic wastes
Water pollution from agriculture and the agro-industry is more common, particularly in the terai and inner terai districts. The processing of jute fibres and the intensive use of fertilisers and pesticides are known to have affected water bodies. However, the affect on aquaculture is not servere at present. Small-scale rain fed ponds are unlikely to be affected by water pollution.
The increased loading of toxins and nutrients derived from domestic wastes has caused severe pollution problems in most rivers and lakes located near urban areas, notably the rivers Bagmati and Bishnumati of the Kathmandu valley. Microbial contamination and low dissolved oxygen also occur as a result. These problems have not only changed the ecological balance of the rivers but have greatly threatened the biological diversity of the ecosystem. Fish culture has been proposed as a method of reducing such environmental impacts, either through stocking or the development of sewage fed fish culture. Domestic and city sewage is a serious source of pollution around larger urban centres. In the Kathmandu valley, domestic sewage and industrial effluent are discharged into the Bergamot, Bishumati and other rivers.
Rice-fish culture has declined due to the culture of high yielding varieties of rice which need insecticides and pesticides. The contamination of water in rice fields with pesticides may have an adverse effect on fish production. However, there is little information on this subject.
Increased agriculture activities, unplanned urbanisation and development of the tourism industry in the vicinity of the Pokhara Valley has started to generate serious environmental threats to lakes. These activities have resulted in increased draining of agro-chemicals and urban sewage during the flood season and have been the cause of increased pollution in lakes. Collectively, such environmental problems not only have adverse effects on the ecology of lakes and the surrounding environment, but also have impacts on aquaculture development activities in the lake.
At present, however, such eutrophication of lakes and reservoirs may have had a positive impact on aquaculture (and fisheries) production from lakes in the Pokhara Valley. More details on this subject are given in the in-depth study in Section 5.
In the vicinity of Indrasarobar hydroelectric reservoir, the increasing trend towards intensive potato farming is thought to have caused pollution problems by the flushing of agrochemicals into the reservoir during the annual monsoon. A survey of ponds in Kathmandu valley showed that there were about 21 ha of ponds, of which 75% are now abandoned because of pollution and water weeds.
In other areas, “religious ponds” are also heavily polluted with organic matter, giving rise to fish kills in summer months.
4.2 Impacts of aquaculture on the environment
There is little detailed information on the positive or negative impacts of aquaculture on the environment in Nepal. There is a need for more detailed studies to determine impacts and identify strategies to ensure that the aquaculture industry develops in a sustainable manner.
Positive impacts on the environment
There are some potential areas where aquaculture can contribute significantly in sustaining the ecological balance of water resources in Nepal. Aquaculture in existing undrainable village ponds in the urban vicinity has shown its positive impact on the environment in maintaining a balanced pond ecosystem and healthy surroundings for the citizens. These ponds provide sites for public utility too. Over the last two decades, aquaculture operations in the lakes around Pokhara appear to have utilised increased nutrient inputs from sewage and fertilisers in fish production. Thus, the utility of this activity has probably been very significant in maintaining the ecological balance of lakes and their surrounding environment.
There is also interest in integrating aquaculture and fisheries development into wetland conservation programmes. The approach being considered is based on the premise that aquaculture and fisheries have the potential to increase economic returns from wetland areas, providing greater economic justification for their preservation (Pradhan and Shrestha, 1992). This interesting concept is worthy of greater consideration.
Environmental impacts related to pond culture
The adverse effects of aquaculture are likely to be most serious with intensive finfish culture, particularly in terms of sedimentation in the pond, water quality deterioration and the release of organic material and nutrients from ponds. However, intensive aquaculture is not widely practised in Nepal and so such impacts are considered minimal.
Self-pollution by intensive finfish ponds and hatcheries due to overstocking, lack of water exchange and inefficient dispersal of effluent, have been identified as significant constraints to the development of the industry. These factors result in the deterioration of water quality, of which low dissolved oxygen and the release of hydrogen sulphide are particular problems in ponds. Such changes tend to affect the yields and profitability of pond farms and not the external environment.
There are a number of chemicals used in aquaculture in Nepal (Table 9), however, so far no significant impacts on the environment have been recorded.
Table 9. Chemicals used in aquaculture in Nepal
|Chemical Name||Dose Rate||Purpose|
|Lime||500 kg/ha/yr||Pre-stocking operation for extensive/semi-intensive ponds.|
|Nitrogen fertiliser||220 kg/ha/yr||Post-stocking operation for extensive/semi-intensive ponds.|
|Phosphorus fertiliser||345 kg/ha/yr||Post-stocking operation for extensive/semi-intensive ponds.|
|Malachite green||0.1 – 1 ppm||Treatment against parasites.|
|Trichlorofon||0.25 ppm||Treatment against parasites.|
|Copper sulphate, formalin, potassium permanganate, dipterex, neguvon, terramycin, tetracycline, acriflavine and common salt (NaCl) are also used for treatment of disease. Malathion is also used to control pond predators.|
Interactions between aquaculture and native species
No significant interactions between cultured and wild fish, or introduced and indigenous fish, have been recorded so far. The Government has introduced tilapias for experimental purposes, but so far these fish have not been released to the private sector (because of concerns over potential negative impacts on wild fish populations). Aquaculture in Nepal has the potential to contribute to the preservation of native fish species. A new project is being undertaken to breed several indigenous species, sahar (Tor sp.), asala (Schizothorax sp.) and kale (Accrosochielus hexagon) which will be released into natural waters.
A study of Pokhara lakes has shown that introduced Chinese carps may have had some negative effect on native species. This is discussed in more detail in Section 5.
Social conflicts and aquaculture
Intensive finfish pond farms and hatcheries and (to a lesser extent) extensive pond farms, compete directly with agriculture for water and land space and for supply of fertiliser. Pond farms also compete with domestic water users for water supply. There is some conflict between finfish cage farmers for space on lakes (see Section 5), but there is no competition with industry at present. Such problems are negligible at present but will require greater consideration in the future.
In general, the problems mentioned above are only now starting to be identified, and solutions are being sought.
5. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: IN-DEPTH STUDY
5.1 Pond culture of carps in the terai
In Nepal, pond culture of carps began in 1947 with the indigenous major carps: bahakur (Catla catla), naini (Cirrhinus mrigala) and rohu (Labeo rohita). Later, during the 1960s and 70s, four commercially high-valued exotic species: common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), bighead carp (Hypophthalmichthys nobilis) and grass carp (Ctenopharyngodon idella) were introduced to Nepal for adopting the polyculture system of carp farming in ponds.
The pond culture of carp commenced in 1981, with the implementation of the Aquaculture Development Project supported by the Asian Development Bank and UNDP. This project has contributed to the remarkable growth in the pond culture industry. Fish production from ponds increased from 740 tonnes in 1981/82 to 8,215 tonnes in 1992/93, which shows an increase of over ten times within a decade. The total value of fish production from pond fish culture was estimated at around US $ 10.5 million and contributed to over 98% of the total aquaculture production of 8,419 tonnes and about 56% of the total fish production of 14,775 tonnes in Nepal during 1992/93. Data compiled for 1992/93 indicates that pond culture of carps seems to have emerged as a very viable and popular activity in the central and eastern terai, more so than in other parts of the country. About 95% of ponds are found in the terai, producing around 98% of the total production from pond culture (Table 10). The Central Development Region constitutes around 36% of ponds and produces about 44% of total fish production from pond culture of carps.
Table 10. Details of pond culture of carps in different geographical locations and development regions of Nepal 1992/93.
|Water surface (ha)|
|Fish production (tonnes)|
The major techniques that have been adopted in Nepal for the development of carp polyculture in ponds in Nepal include: regular (extensive); improved (semi-intensive); and intensive. These systems are categorised on the basis of production input levels and outputs. The details of recommended inputs and expected outputs resulting from these techniques, as well as recommended general stock composition are shown in Tables 11 and 12. A comparative overview of the details of area coverage, production and productivity accomplished by adopting these techniques during 1992/93 is shown in Table 13.
Table 11. Recommended input/outputs of major aquaculture production systems in Nepal.
|Details of Production system||INPUTS (/ha)||OUTPUTS|
|1 – 2 g||5 – 10 g||(kg)||(kg)||(kg)||(kg)|
|Pond fish culture|
|7,000||-||500||-||-||0.8 – 1.5|
|10,000||7,000||500||220||345||2,850||1.5 – 3.0|
|Rice-fish culture||5,000||-||-||-||-||0.3 – 0.5|
|Fish culture in other areas||7,000||-||-||-||-||0.3 – 0.8|
Table 12. Recommended stocking composition in polyculture systems (FDD, 1993).
|Details of Species||Combination|
|Common carp||20||Species combination applicable to all pond fish culture activities.|
Table 13. Comparative details of area coverage, production and productivity in aquaculture in Nepal, 1992/93.
|Particulars||Area Coverage||Fish Production||Productivity|
|1. Pond culture||4,593||100||8,215||100|
|2. Rice-fish culture||56||17||0.3|
|3. Other areas fish culture (extensive)||61||20||0.33|
|4. Cage culture in lakes (m3)||10,639||53||5 kg/m3|
|5. Enclosure fish culture in lakes.||4.4||9||2.04|
|6. Open water stocking in lakes||-||50||-|
5.1.2 Impacts of the environment on pond culture
Siltation is an acute problem over large areas of the kingdom and is expected to continue to be so in the foreseeable future. Another related problem is the flooding of low-lying areas during monsoon periods, causing physical destruction of ponds as well as loss of stock. The ponds in the terai and inner terai districts suffer from physical changes, such as flooding and heavy siltation during monsoons and drought during the dry season, both of which may lead to production losses and physical damage.
5.1.3 Environmental impacts of pond culture
See section 4.2 for review.
5.2 Cage and pen culture in Pokhara Lakes
Cage fish culture was introduced in the lakes of the Pokhara valley several years ago. It has been considered to be a remarkable step towards the development of natural water resource management for aquaculture production in the country. Cage fish culture in lakes with herbivorous carps (major species: silver carp and bighead carp) has been quite successful in Nepal. This practice has been recognised to be economically viable also. At present, cage culture activities are being conducted in three major lakes of the Pokhara Valley: Phewa; Begnas; and Rupa. The cage culture of carps in these three lakes is practised in an extensive manner, however, studies are being undertaken to adopt intensive culture of common carp in cages to examine its viability. Some important characteristics of the three lakes as reported by Fisheries Research Centre, Pokhara for 1991/92 are shown in Table 14.
5.2.1 Impact of environment on cage culture in lakes
Cage and pen culture in lakes
As a result of massive deforestation activity in the lake catchment areas and heavy rain during the monsoons, there have been severe landslides and soil erosion. The surface run-off water from these areas carry enormous amounts of silt and organic wastes and drain into lakes. Siltation problems are particularly acute in Lake Phewa and Rupa in the Pokhara Valley. The details of land use in the Lake Phewa watershed study are given in Table 15.
Table 14. Physical and limnological characteristics of three important lakes.
|Air temperature (°C)||8.0 – 33.0||9.0 – 32.2||9.0 – 31.0|
|Max. depth (m)||24||10||6|
|Average depth (m)||7.5||6.6||3|
|Maximum temperature (°C)||29.5||32.0||30.0|
|Minimum temperature (°C)||15.0||15.2||14.0|
|pH||7.0 – 8.8||6.4 – 8.5||5.6 – 7.8|
|Transparency (m)||1.5 – 3.3||1.2 – 3.4||0.8 – 1.8|
|Dissolved oxygen (mg/l)||6.1 – 12.3||5.3 – 14.3||5.0 – 8.9|
|Watershed area (km2)||110||19||30|
Table 15. Land use in the Lake Phewa watershed (from ADB, 1993).
|Fans and tors||31.8||2.6|
Eutrophication of lakes
Increased agriculture activities, unplanned urbanisation and development of the tourism industry in the vicinity of the Pokhara Valley have begun to generate serious environmental threats to the lakes. These activities have resulted in increased draining of agro-chemicals and urban sewage during the flood season and have been the cause of increased pollution in lakes, including increased signs of eutrophication such as algal blooms. Collectively, such environmental problems have not only caused adverse effects on the ecology of lake and the surrounding environment, but have also impacted on aquaculture development in the lakes. At present, however, eutrophication of the lakes may have had a positive impact on aquaculture (and fisheries) production from lakes in the Pokhara Valley leading to increased production of filter feeding carps. The details of production of Chinese carps from the three Pokhara lakes during 1990/91 - 1992/93 are given in Table 16.
Table 16. Production (tonnes) of Chinese carps from the three Pokhara lakes during 1990/91-92/93.
5.2.2 Impact of cage culture on lakes
Positive impacts on the environment
Over the last two decades, aquaculture operations in the lakes around Pokhara appear to have utilised increased nutrient inputs from sewage and fertilisers into fish production. Thus, the utility of this activity has been very significant in maintaining the ecological balance of lakes and their surrounding environment. An estimated removal of nitrogen and phosphorus by cage and pen culture in Lake Phewa for 1992 is included in Table 17. The impacts of this nitrogen (N) and phosphorus (P) on the ecology of the lakes remains to be studied, however.
Table 17. Estimated removal of nitrogen and phosphorus from cage and pen culture in Lake Phewa for 1992 derived from data given in ADB, 1993.
|Particulars||Fish yields (tonnes)||Phosphorus removed1|
1 Assuming P content of fish = 0.34% of harvested weight.
2 Assuming N content of fish = 2.56% of harvested weight.
3 Assumes P and N addition with fry/fingerlings is not significant.
In fact, the amount of N and P removed will be slightly less than predicted because a small amount is added to the lakes as fish fingerlings. As there are no disease problems, no chemicals are used to treat the fish. A salt solution (NaCl) is used as a dip treatment for fingerlings before stocking them in the cages. Such treatments will have no impact on the environment. Ultimately, there will be a finite “carrying capacity” for cage culture in the lake, depending on the stocking density and primary production. There is evidence that the carrying capacity in Rupa may have been reached through overstocking where crowding of cages together resulted in a decrease in the growth rates of caged fish.
Impacts on native fisheries
There may have been some impacts of the cage/pen culture on native fisheries as there have been some escapes from the cages. Chinese and major carps (bighead carp, silver carp, grass carp, common carp and rohu) have also been introduced into the lake as part of a fisheries development programme. The stocking appears to have been very successful, with increased catches recorded by local fishermen. However, there is evidence that over this time some of the indigenous species have declined in abundance. The reasons for this decline are unclear but may be related to stocking of non-indigenous species (Swar and Gurung, 1988). The indigenous fish species usually command a higher price, therefore the economic loss is more significant than the reduction in yields. To avoid competition with indigenous species, it has been suggested that stocking be limited to only bighead and silver carp. A stocking programme for indigenous species is also being developed.
Management of environmental impact
A Fisherman's Association manages aquaculture on the lake, however, problems are emerging due to conflicts with other users of the lakes. There are claims by local interest groups that cage culture is having negative impacts on water quality -- although this is largely unsubstantiated. The concern has arisen because water quality in the lake appears to be deteriorating. A recent ADB sponsored study has shown that the main source of pollution is the urban development occurring around the lake (ADB, 1993). However, cage farms have become a visible target. In fact, the cage farms are probably contributing to the control of eutrophication in the lake. As shown above, the cages in Lake Phewa may be removing around 272 kg of phosphorus and 2,048 kg nitrogen per year, at current fish production levels. This may have an effect on controlling eutrophication of the lake. There is a need for publicity now to be given to the positive aspects, mainly related to concern over the deteriorating lake environment -- and the effect on tourism of this deterioration.
5.2.3 Summary of lessons learnt and follow-up
It is important to get the balance right between cage culture and the overall management of the lake, particularly in relation to carrying capacity.
It is important to consider integrated management of the watershed/lake -- including dialogue and communication between the different lake users.
The possible role of environmental monitoring.
The need for an integrated management plan, where fisheries and aquaculture are one component in the overall development planning for the lake is recognised as important. Studies are required to determine the carrying capacity of the lake, considering both cage and pen culture and capture fisheries. There may even be a need to increase cage production to reduce eutrophication effects. The desire to introduce more intensive cage culture (e.g. of common carp) should be carefully thought through, because more intensive cage farming has the potential to contribute to eutrophication.
A programme to promote the indigenous fish species may be undertaken, involving stocking, community participation in habitat protection and perhaps improved public awareness of indigenous species. Such a programme could well fit into the “tourist” developments at Pokhara and help to promote the importance of a healthy and clean lake environment.
6. PRIORITIES FOR DEALING WITH ENVIRONMENTAL PROBLEMS
There is an awareness in Nepal that the social and economic development of the country is linked to the sustainable development and utilisation of the country's natural resources. One of the country's most important natural resources is water. The proper management and rational exploitation of this resource plays a vital role in determining the direction of the national economy. Power generation activities and irrigation works are important developmental sectors in which water is invested for faster economic growth of the nation. Similarly, fisheries development should also be accorded due priority in the national development plan. Fisheries development programmes have a direct relationship with aquatic life and such activities will only thrive if the quality of the aquatic environment is maintained. Therefore, implementation of any development activity involving water resources must give greater consideration of the potential impact of this development on aquatic ecosystems and fisheries development.
It is also necessary to identify any adverse environmental impacts relating to the planning of fisheries development programmes themselves. In connection with this, some specific studies have to be undertaken in relation to the environment and aquaculture development in Nepal are suggested below. These activities can be broadly divided into research, information exchange, training and strengthening of legislation.
6.1 Management of impacts of environment on aquaculture
There is a need for research on cost-effective engineering/technological measures which can be taken to avoid problems due to flooding, siltation and other major environmental changes.
There is a need for research on the effects of urban and industrial pollution on fisheries and aquaculture resources. The qualitative information available needs to be substantiated with quantitative data, which can be used to develop suitable strategies to minimise impacts on fisheries. Likewise, the use of aquaculture to reduce impacts of pollution needs to be examined (e.g. sewage-fed fish culture).
To encourage and promote fish culture in the paddy fields of Nepal, studies are required to assess and evaluate the impacts of pesticide use in paddies on tolerance levels in fish, production losses and product contamination. The potential for integrated pest management involving fish as a means for reducing pesticide use should be evaluated.
There is a need to evaluate the impacts of environmental change in river systems on fisheries. Such a study would provide basic information on the status and severity of environmental problems that have hindered the expansion of aquaculture and fisheries activities; endangered the existence of important aquatic species; resulted in loss and contamination of fishery products; and caused human health hazards. This should include the range of developmental activities related to river ecosystems (e.g. damming, irrigation) in order to make informed planning decisions for sustainable development activities in the Kingdom.
6.2 Management of environmental impacts caused by aquaculture
Pond aquaculture has emerged as a very viable and popular activity in Nepal. Presently, it contributes about 63% of the total fish production in the country. There is a need for intensification and further expansion of fish pond production. However, its expansion has been greatly hindered by the assumption that it would create environmental problems in the country. Therefore, due priority must be accorded to undertaking studies in order to assess whether the environmental issues relating to pond aquaculture really do pose a serious problem and, if so, what remedial measures can be adopted.
There is also a need to increase awareness of the positive impacts of aquaculture in existing undrainable village ponds.
There is also a need for extension of information to farmers on maintaining a balanced pond ecosystem and hygienic pond environment.
Investigative studies into the suitability of swampy and marshy lands around irrigated areas and flood plains for aquaculture and fisheries production should be undertaken. Policies should be developed with respect to the amount of production to be afforded such ecosystems.
As seen in Pokhara, aquaculture may come under increasing public scrutiny, partly because people are ill-informed about the environmental impacts of aquaculture. There is a need to promote the positive impacts of aquaculture development. The problems that have arisen in Pokhara indicate a need to take a more “holistic” approach to aquaculture development. This approach requires that aquaculture (and fisheries) be integrated into a planning and management scheme for natural resources that considers the positive and negative impacts of all sectors.
There is also a role for aquaculture in conserving stocks of indigenous fish species. This aspect needs to be explored in more detail.
The potential positive contribution that aquaculture and fisheries development can make to wetland conservation needs to be explored further, possibly through some pilot studies in selected areas.
7. FUTURE AQUACULTURE DEVELOPMENT AND RECOMMENDATIONS
In view of the environmental implications in Nepal, the following recommendations are made for the expansion and sustainability of future aquaculture development in Nepal.
Application and choice of appropriate aquaculture methods which will have a positive effect on the environment.
Need for proper sectoral development planning and management to promote aquaculture in a specific manner.
Integration of aquaculture into other multi-sectoral aquatic resource management frameworks.
Separate legislation needed relating to aquaculture.
Need for an agency to assess and monitor regularly the ecological, environmental and socio-economic changes associated with aquaculture development.
Application of genetic engineering for stock improvement. This would help the resistant and fast growing species/strains as well as increased production with optimum fertilisation and feeding.
Attention to be paid to improved pond engineering and site-selection to overcome possible threats like flooding and siltation, e.g. in ponds.
The use of more biological fertilisers (bacterial fertilisers) to increase pond fertility and restore pond ecosystems in order to lessen the use of chemical fertilisers which may have harmful effects.
ADB, 1993. Environmental protection study of Phewa Tal, Nepal. Asian Development Bank Contract Number: CPCS/92–335. April 1993.
FDD, 1993. Annual Progress Report (1992/93). - Fisheries Development Division (FDD), Department of Agriculture Development, HMG, Lalitpur, Nepal.
NARC, 1991/92. Limnological study of three lakes (Phewa, Begnas and Rupa) of the Pokhara Valley, Kaski, Nepal. Annual Technical Report (1991/1992), Nepal Agriculture Research Council, Fisheries Research Centre, Pokhara.
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