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10. Summaries of the country reports presented by the National Environment Co-ordinators are given below, along with highlights of the ensuing discussions aimed at clarifying the key points of the presentations. A summary of the Pakistan report submitted to the workshop, is also included.

The full country reports appear as Annexes II-1 to II-17.

11. Bangladesh. Aquaculture plays an important role in nutrition and in the national economy of Bangladesh. Inland open-water capture fisheries and inland closed water fisheries countribute 46.5% and 28.5% respectively, to a total fish production of 1.04 million tonnes. Polyculture of carps and monoculture of tilapia and various catfish species are commonly practised in freshwater. Intergrated fish farming with duck, poultry and cattle is also practised. Brackishwater shrimp farming is based on traditional and improved traditional methods which rely on the collection of wild seed.

12. Aquaculture development has suffered from man-made interventions in riverine morphology, disruption of ecology, application of agro-chemicals, use of water for irrigation purposes and polluting effluent from modern developments. In brackishwater shrimp farming, soil erosion, heavy siltation, salinity and oxygen fluctuations, mangrove disruption and land use conflicts are emerging as the major problems, along with the indiscriminate collection of juvenile shrimp. There are few regulatory mechanisms to protect aquaculture environments, however, any development projects including fisheries have to ensure that no negative impact on the environment will occur. There is a need to raise public awareness and training on issues related to the interactions between aquaculture and environment.

13. Discussion: The ensuing discussion focused on socio-economic consequences arising from shrimp culture, in particular the conflicts among the various farming groups over the use of land for shrimp, rice and salt production. Salinisation resulting from shrimp farming can seriously affect the livelihood of rice farmers who do not receive any compensation for damages suffered, and subsequently have to lease their land to wealthy shrimp farmers.

14. Cambodia. Although aquaculture in Cambodia is still in an early stage of development, some environmental problems have occurred. Deforestation in the major watersheds has resulted in high sediment loads, floods in the wet-season, turbulence, increases in water temperature and shallow waters in the dry season which particularly affected Pangasilidae and cyprinid culture units in areas of the Tonle Sap river. In addition to the physical modifications of riverine habitats and pollution due to run-off of agro-chemicals and urban sewage, the collection of wild seed for aquaculture may contribute to a significant decline in wild fish stocks. The main environmental impacts from inland cage and pen culture are due to very irregular feeding practices. In some cases, farmers dump 1–3 tonnes of trash fish into the culture units once every 3–5 days. In other cases, farmed fish are starved for weeks before being provided with an excessive amount of feed, which results in poor feed consumption, an accumulation of trash fish in cages and high organic pollution. Self-pollution in cage culture areas is therefore a widespread problem. Improvements in feeding strategies through strengthened extension services and training is recommended. Formulation and manufacture of low-cost feeds with nationally available ingredients is a priority. There is a lack of formal study on the environmental impact in shrimp farms in coastal areas. The boom in shrimp farming has caused the government great concern because of the mangrove clearing practices of shrimp farmers, in addition to people that are clearing the mangroves for other purposes. However, the government's efforts in coastal zone management and planning for aquaculture are being studied and promoted.

15. Discussion: Inland cage and pen culture farms often suffer from aquatic pollution problems because they are commonly located in, or close to, urban and village areas. Other problems include poaching, which is particularly frequent in periods of fish scarcity, and which requires constant patrol of the fish farm. Poor feeding practices are related to fluctations in the market availability of captured fish, including trash fish. Trash fish is also being used as feed for other animals. It was mentioned that wild fish seed (Pangasius sp.) is being collected for export purposes, which is of serious concern for the safeguard of wild fish populations. Apparently, shrimp farmers are reluctant to locate their farms beyond the mangrove belt. All inputs (particularly feeds) for intensive shrimp farming are imported.

16. China. China has experienced a rapid development in aquaculture over the past decade, which is reflected in its increasingly high total annual production. Increased production has resulted largely from the refinement of existing technology and, to some extent, expansion of culture area. Along with this development, has come issues and problems related to: (i) interactions between aquaculture development and the environment; and (ii) aquaculture in conflict with other resource users. These problems are serious in coastal provinces where both inland and coastal aquaculture are more developed. Environmental pollution has hindered the development of aquaculture due to increasing waste discharges as a result of rural industrial growth and the discharge of city sewage.

17. China has established legislation for the protection of fishery environments, such as the national standard of water quality for fisheries, the protection of spawning beds, breeding farms and compensation for loss of fishery resources caused by pollution. However, great efforts are still required to improve and up-date the legislative system of the country concerning the protection of the environment for fisheries and aquaculture. Apart from the effects of environmental pollution on aquaculture, self-pollution and impacts of aquaculture activities on the environment are preventing aquaculture, especially coastal aquaculture, from developing on a sustainable basis.

18. To assess and evaluate impacts on the environment, some studies have been carried out in inland waters and coastal areas in China to provide a basis for the development of counter-measures to cope with problems of self-pollution and impacts on the environment. At present, it is considered necessary to establish an aquaculture environment research centre in China for a long-lasting, efficient protection of the fishery environment. This centre will be responsible for research, training and exchange of information on fishery environmental protection.

19. China recommends the establishment of a regional aquaculture and environment information exchange system in Asia-Pacific, which is needed for countries in the region to share experience. A programme for training personnel from countries like China in legislation concerning aquaculture and the environment, is also very necessary. Finally, it recommends that a regionally co-ordinated case study on integrated coastal aquaculture/fisheries operation should be conducted. A pilot study on the subject is recommended to be established in the Bohai because of the sea's economic importance and the presence of typical environmental problems. China has already done a lot of research work on the environmental problems of the Bohai.

20. Discussion. With regard to policies to reduce environmental pollution by economic means and to levy compensatory fees for environmental resources, it was mentioned that it is not easy to apply the polluter-pays principle because of the difficulties in identifying the pollution source. It was suggested that economic valuation methods related to environmental interactions of aquaculture still need to be developed. Monitoring plans for the protection of living aquatic resources are foreseen. Causes of diseases leading to the sharp decline in last years shrimp production were discussed, including introduced pathogens, poor feed handling and inappropriate water quality management. It was recognised for several countries that the current problems of increased hypernutrification and eutrophication, severe disease outbreaks, water quality mismanagement, and overcrowding of culture units, were generally related to lack of planning and management of the aquaculture industry.

21. Hong Kong. The development of inland pond fish culture and coastal finfish cage culture has been limited by a shortage of suitable sites and pollution problems. Rapid urban development in the New Territories and the filling up of fish ponds to serve as open storage container sites, have led to a rapid reduction in fish pond area. Recent amendments to the Town Planning Ordinance have enabled enforcement against unauthorised change of land usage in specific areas. Efforts are now directed to retain fish ponds around the Mai Po Marshes, a migratory bird sanctuary, for conservation and flood control purposes. Streams are seriously polluted by livestock and domestic wastes discharges. Pond fish farmers therefore rely on rain or well water and adjust stocking species composition to minimise the need for water exchange. Control of discharges into inland and coastal waters started in 1987 with the sequential declaration of water control zones under the Water Pollution Control Ordinance. Control of livestock wastes also started with the enactment of the Waste Disposal (Amendment) Ordinance and was supplemented by the establishment of waste treatment demonstration plants, a livestock waste collection service as well as the introduction of effluent-free pig-raising methods.

22. To protect coastal finfish cage culture and to avoid conflicts with other coastal water users, the government enacted the Marine Fish Culture Ordinance in 1982, requiring all marine finfish culture to be conducted in designated fish culture zones. Urban development had led to a deterioration of water quality in some fish culture zones e.g. Inner Tolo, but the situation has shown some improvement with the declaration of water control zones and implementation of the Water Pollution Control Ordinance. Further improvement is expected as a series of sewage master plans for different districts have been drawn up and are to be implemented in various stages. Recently, large scale coastal land development has led to the clearance of these fish culture zones and caused serious environmental impacts to a number of nearby fish culture zones. Ex-gratia allowance payment for affected fish farmers are arranged.

23. A study on environmental impacts of coastal finfish culture has identified fish faeces, feed leachate, unconsumed feed, foulers from cage cleaning and improper disposal of refuse as the major sources of pollution. The government has taken action to reduce the raft density in fish culture zones with limited tidal flushing, stepped up regulatory control on structures on rafts, developed suitable non-polluting feed to replace trash fish and educated farmers on proper refuse and waste disposal. The possibility of open sea cage culture is being studied.

24. India. The country produces about 40,000 tonnes of shrimp from an area of about 70,000 ha and about 1.2 million tonnes of freshwater fishes from about 670,000 ha of freshwater ponds. It has a built-up shrimp hatchery capacity of about 1 billion seed per year, and produces about 12 billion fry of carpas per year. Tiger and white shrimps in brackishwater and major carps in freshwater are the main species contributing to aquaculture production. Semi-intensive shrimp culture can yield about 5 t/ha/year and carp production is 10–15 t/ha/yr.

25. The environmental impacts on aquaculture are as follows:

26. The impact of aquaculture on the environment are as follows:

27. The case studies, to illustrate the above interactions are summarised as follows:

28. Although serious consideration is being given to the environment at national level, due to the absence of regulations, development is haphazard except for large-scale farms which need an EIA and approval. The World Bank-assisted project on Shrimp/Fish Farming has carried out EIA and has built in an Environmental Monitoring and Management Programme. The Coastal Regulation Zone (CRZ) Notification and the Water (Prevention and Control of Pollution) Act have provisions for coastal zone management, but specific Acts/Regulations for aquaculture are lacking. The issues are being discussed for guiding aquaculture development properly. At farm level, management needs a lot of education, training and extension services.

29. Aquaculture has been given one of the highest priorities in terms of policy, strategy, and planning at national level and the open economic policy provides liberal support. The Government has both people-oriented and production-oriented development programmes. The policy is supportive of semi-intensive culture systems. Scientific data on environmental impact needs to be generated to be able to advise the policy makers and planners on sustainable development of aquaculture.

30. India's recommendations include:

31. Discussion: Possible effects of stocking practices in small water bodies, such as potential degradation of biological diversity were mentioned. Differences between culture-based fisheries and aquaculture were highlighted, in particular the question of ownership over the released and captured stock. Attention was drawn to existing conflicts between oxbow lake fishermen and farmers claiming land for agricultural purposes.

32. Indonesia. Aquaculture is a source of living for some 1.8 million people in Indonesia, it contributed 15% to total national fish production in 1991, and generates foreign exchange earnings. Main aquaculture practices include brackishwater pond culture, freshwater pond culture, cage culture in reservoirs and paddy-cum-fish culture in rice fields.

33. In some cases, cage culture of common carp and tilapia, based on intensive feeding, has suffered from upwelling of hypoxic waters, resulting in severe losses in reservoirs. Management measures taken include limitation of the area and number of new cage culture units, zonation of various uses (such as public transportation, fishing, aquaculture, tourism) and strengthened extension efforts.

34. Environmental problems in shrimp culture include: (i) disease outbreaks resulting from poor site selection, inappropriate design, mismanagement, bacterial, viral and fungal infections; (ii) consequences of mangrove destruction such as siltation, sedimentation, coastal erosion, and disruption of biological diversity; (iii) aquatic pollution derived from urban and industrial waste discharges; and (iv) aquaculture self-pollution.

35. Enforcement of existing laws is weak due to a lack of detailed regulations and penalties, political pressures and social problems, such as illegal settlement and aquaculture operations in protected mangrove areas.

36. To address the above environmental problems, it is recommended that extension to farmers be intensified and environmental impact assessment introduced. A programme could be launched to improve tambak irrigation systems, in co-operation with the Public Works Department and donor institutions (IBRD, ADB), to include re-design and reconstruction of canals, extension, support in input supply and harvesting (including market development) and promotion of the nucleus estate management system. Recent efforts to protect mangrove areas involve the establishment of a protected Green Belt combined with a sylvo-fisheries programme for designation of 20% of the total mangrove area for aquaculture purposes. In addition, there is a need to establish shrimp health management and disease control schemes to include laboratory facilities, training and extension services.

37. Studies on aquaculture and environment should be continued through strengthened close collaboration of the institutions concerned. Training and extension, as well as exchange of experience, information and technical staff should be promoted, and regional and international co-operation should be enhanced by NACA, EC, ADB, UNDP/FAO and others.

38. Discussion: There are problems with enforcement of laws and regulations related to aquaculture. The group briefly discussed the formulation of environmental quality objectives, criteria and standards and it was questioned whether it would be possible to harmonise effluent standards. It was recognised that effluent standards for freshwater aquaculture should be different from those for coastal aquaculture.

39. Iran. With an area of 1.65 million km2 and a population of about 60 million, Iran is located in a semi-arid region in West Asia. While a small part of the country along the Caspian Sea receives ample rainfall of 1255 mm/year, average precipitation for the whole country rarely exceeds 300 mm/year.

40. Although fish has not been a traditionally common food item in the people's diet, it is becoming increasingly important as an alternative source of animal protein. Success in mass propagation of fish fingerlings to replenish and enhance fisheries stocks (e.g. sturgeon and Rutilus sp.) in the Caspian Sea in the early 1980s, led to inland aquaculture development and expansion of the fisheries enhancement programme to other natural and man-made water bodies. This two-pronged approach is aimed at achieving the dual objectives of increasing the production of animal protein for the rapidly growing population and raising the living standards of fish farmers, coastal fishermen and coastal communities. In 1991, more than 10,000 citizens were additionally employed in fish farming and related fishing activities through this approach. Fish production in 1992, derived from 7,365 ha of farming facilities and about 500,000 ha of water bodies amounted to about 22,000 tonnes and 20,000 tonnes respectively, totalling about 42,000 tonnes. This represents about 12% of the total fishery production (354,000 tonnes) in Iran. The Chinese major carps were the main species cultured, accounting for 97% of total inland aquaculture production.

41. The Government of the Islamic Republic of Iran places much importance on the protection and conservation of the environment in relation to sustainable development with the promulgation of Act 50. It also organised a national workshop in May 1993, after more than a year of preparation and study, to formulate the National Strategy for Environment and Sustainable Development in collaboration with the World Bank and UNDP.

42. While fisheries enhancement has both negative and positive impacts on the environment, it is the environment which is impacting on aquaculture through pollution of its water supply with industrial and urban discharge along with agro-chemical run-off. This is demonstrated by the two case studies, which comprise documentation of its development and identification of potential environmental issues. However, with its expansion into coastal aquaculture and mariculture, the interactions between the environment and aquaculture will become more pronounced. It is in this context that the Iranian delegation looks to the FAO/NACA Workshop for guidance in the identification of priorities in relation to the environmental implications of its future aquaculture development programme. It hopes to learn from the experiences of other Asian countries in dealing with environmental problems related to aquaculture development, and to establish institutional linkages in research, training and information exchange through TCDC activities at the regional level.

43. Discussion: It was emphasised that lessons from other countries have been learnt and new shrimp farmers are advised to apply semi-intensive culture methods. The government of Iran is proceeding carefully in the introduction of tilapias, cyprinids and Macrobrachium sp. and promotes feasibility studies on an experimental basis.

44. Korea (Republic of). Aquaculture production amounted to 789,000 tonnes with an economic value of 0.36% of GNP in 1991. Coastal aquaculture is more important than inland aquaculture in the Republic of Korea. About 40 species are cultured, of which more than 30 species are marine. From the viewpoint of production, seaweed culture is the most important, but finfish culture is more important with respect to environmental impacts. Seaweed culture is done mainly along the south-western coast. The coastal water is in a eutrophic state, or under the process of eutrophication, caused mainly by the discharge of domestic and industrial wastewaters. In Hakrhim island near Chungmu city, water-borne pollutants probably originating from intensive finfish culture influence water quality. Harmful algal blooms, summer anoxia and toxin contamination of shellfish are three important constraints to aquaculture production. Sedimentation of organic substances and disruption of benthic and pelagic flora and fauna are other important problems. Additionally, guidelines are lacking for the control of chemotherapeutants used to cure fish diseases.

45. The impacts of environment on marine aquaculture are: (i) water pollution and accumulation of pollutants in animal tissue; (ii) harmful algal blooms and anoxia, and (iii) disturbance of coastal habitats.

46. As a corrective measure, regulations on environmental management include: (i) water quality and effluent standards; (ii) EIA; (iii) designation of special management coastal sites such as “clear zone”, “coastal site for special management of pollution” and “fisheries resources conservation areas”. Korea will soon establish a “total amount effluent control system” instead of water quality standards to strictly regulate the discharge of terrestrial wastewaters into the sea. Existing monitoring activities to detect water quality changes and red tide observations will be strengthened.

47. The influence of aquaculture impacts on the environment caused mainly by intensive culture are: (i) production of food remnants and faecal organic substances; (ii) accumulation of dead animals, buoys, net, rope and other materials; (iii) interference of navigation and tidal action; and (iv) disposals of shells.

48. In order to minimise these impacts, all aquaculturists should have a license and must clean the farm bed regularly. The government regulates the stocking density and the distance between sites, licensed areas and the ratio of the culture area to licensed area.

49. Discussion: Priority is now focused on resolving current environmental and production problems To strengthen efforts at ensuring sustainability, future aquaculture research projects and development activities will be addressed to develop polyculture technology based on the food chain and energy flow of ecosystems, and selective breeding and hybridisation. Furthermore, the country is developing wave-resistant culture systems and low-phosphate feeds. On coastal zone management, the effects of artificial reefs made of concrete, which were constructed extensively in the Republic of Korea, for the protection of the coastal environment and enhancing fish productivity, were described as beneficial.

50. Lao PDR. To date there are no records of serious incidences of environmental hazards by aquaculture operations or external effects upon aquaculture, since aquaculture is only at an early stage of development. No serious environmental problems are expected in the near future because development of intensive aquaculture and large scale industrial enterprises are still a long way off. However, the Government of Lao PDR is aware of the risks of uncoordinated expansion of aquaculture and is therefore cautious in taking steps to prevent any damage to the natural environment through their national policies.

51. Positive effects of aquaculture development are recognised in the national policies and farmers are encouraged to dig ponds in drought affected areas, mainly to use as water reservoirs for irrigating agricultural land combined with production of fish. Fish culture is also seen as a means of controlling diseases caused by mosquitoes and snails, and to improve hygienic conditions around farmer's households through proper integration.

52. Measures to prevent potential adverse effects upon aquaculture from other human activities are being promoted. This includes the use of easily degradable pesticides and monitoring of shifting cultivation and logging of forests to minimise the effects of soil erosion, such as silting of water bodies and irrigation channels. Water quality of some major rivers and reservoirs is also being monitored.

53. Future fishery control and management strategies are prioritised to include aquatic resources identification, aquaculture and integrated wetland management.

54. Discussion: Efforts to intensify and upgrade existing catfish culture are not yet feasible because of a lack of suitable feeds. Holistic approaches, such as integrated management of wetland areas, were generally favoured since they allow adequate consideration of other resource uses in wetland areas, including traditional capture and culture-based fisheries.

55. Malaysia. With a large potential area for aquaculture, Malaysia could realise its target production by 1995. The upward trend in production value of aquaculture products and export earnings indicates good performance. Available rules and regulations under separate Ministries and agencies could be refined and exercised through a co-ordinated effort to safeguard the environment and the aquaculture industry. Apart from possible setbacks due to impacts of the external environment or vice versa, the target production may be realised if the problems related to all types of pollution by such activities as agricultural, industrial and shipping are recognised and if the rules and regulations are exercised.

56. Sporadic disease outbreaks and mass mortality of fish have occurred in many fish farms, indicating that the impact of pollution cannot be ignored and research and monitoring as part of an environmental management strategy should be conducted.

57. Discussion: It was recognised that there are considerable difficulties in identifying sources and confirming the causes of aquatic pollution affecting aquaculture. Mass mortalities can only be assumed to have been caused by other human activities or natural fluctuations in water quality, e.g. salinity changes recorded in the case studies presented. One participant noted that the report is not furnished with information on the kind and amount of chemicals used in aquaculture. In relation to the dependence of grouper farming on imported wild seed, it was stated that not much information is available on the related effects, that the Government of Malaysia has banned the export of grouper fry and that research on artificial propagation is being supported. A recently started eel culture project is increasingly dependent on wild eel collection, while the prices for eel fry are also increasing. This project also appears to be heavily dependent on ground water supply.

58. Myanmar. Fish is the major source of protein and the fourth largest source of foreign exchange in Myanmar. The country has a potential aquaculture area of 288,000 has of freshwater and swamps and mangroves of 520,000 ha. Aquaculture production increased from 5,493 tonnes in 1987 to 64,501 tonnes in 1993. The major species cultured are the Indian and Chinese carps. Culture of marine shrimp and freshwater prawn is being developed. The African giant catfish Clarias gariepinus has been introduced for hybridisation with C. macrocephalus. The Department of Fisheries has 22 fish seed production stations which produced over 25 million seeds in 1992.

59. In 1989, the government promulgated the Law Relating to Aquaculture which covers administration of land and water for aquaculture, leasing, licensing and inspection of farms, as well as punitive action. The DOF operates a system of licensing to regulate aquaculture development. There are codes of practice for the utilisation of lakes, rivers and reservoirs, but these do not cover mangroves. Live fish export and import has recently been legislated. Forests, pastures and paddy lands are protected areas. Recreation areas and waterways cannot be used for aquaculture. Collection of spawners is banned during the spawning season but collection of seed is permitted with specific restrictions.

60. No significant impacts of aquaculture on environment, or environment on aquaculture, have been reported, but the Government feels the need to formulate a long-term plan for assessing and managing the environment for sustainable aquaculture development.

61. Discussion. The recently established aquaculture law has apparently helped to resolve conflicts between aquaculture and agriculture and other resource users. Introduction of exotic species and wastes discharged from aquaculture operations are well controlled.

62. Nepal. Aquatic environments are increasingly subject to the consequences of deforestation, unplanned urbanisation and industrialisation, which result in drought, floods, soil erosion, sedimentation, siltation, warming and pollution. The fishery and aquaculture activities being affected by these problems are pond aquaculture, fish culture in paddy fields, aquaculture in marginal irrigated areas and flood plains, cage/pen fish culture, open water stocking and lake and reservoir management, and capture fisheries in rivers and natural impoundments.

63. Aquaculture operations in the lakes around Pokhara appear to have utilised increased nutrient inputs from sewage as well as fertilisers used in crop production, thereby maintaining the ecological balance of the lakes and the surrounding environment. Integration of aquaculture and fisheries developments into wetland conservation programmes is being considered, based on the premise that aquaculture and fisheries have the potential to increase economic returns from wetland areas. Self-pollution in intensive fish ponds and hatcheries due to overstocking, lack of water exchange and inefficient dispersal of effluent have been identified as significant constraints. Cage culture has been blamed for water quality deterioration in lakes, although a recent ADB study proved that the main source of lake pollution is urban development.

64. So far no significant impact has been recorded on the use of the limited number of chemotherapeutants. Antibiotics are used only in hatcheries. In general, no significant interactions between cultured and wild fish, or introduced and indigenous fish have been recorded. Tilapias introduced for experimental purposes have not been released to the private sector. Chinese and major carps have been introduced into Pokhara lake as part of a fisheries programme. There is evidence that some indigenous species have declined in abundance. To avoid competition with indigenous species, it has been suggested that stocking be limited only to bighead carp and silver carp.

65. Discussion: The importance of integrated management of watersheds and lakes was recognised. Pond farms compete with agriculture for water and land space and for supplies of fertiliser. Pond farms also compete with domestic users for water supply. There is a need to provide pond farmers with adequate information on maintaining a balanced pond ecosystem and hygienic pond environment. Aquaculture has come under increasing public scrutiny, partly due to misinformation on the environmental impacts of aquaculture. It is important to promote public awareness on the positive impacts of aquaculture.

66. Pakistan. Aquaculture is not traditionally practised in Pakistan, it is a relatively new activity, which explains its small contribution to overall fish production. It is estimated that 20% of all inland fish production come from aquaculture.

67. A number of laws govern efforts to protect air, water and oceans, for waste management control, pesticides and other basic substances, but most of these are out-dated. There is a need to have a single comprehensive law governing environmental control and protection in Pakistan. The Ministry of Environment and Urban Affairs is presently engaged in formulating a comprehensive law which will address the full range of environmental problems.

68. As aquaculture development is in an early stage, the impact of the external environment on aquaculture and vice versa has not been noticed. With a quickening in the pace of aquaculture development, however, the country may face the same environmental problems that other countries are now suffering.

69. The influence of the Indus River system on the marine fisheries of Sindh coast is substantial as this river system has historically transported enormous quantities of nutrients and sediments to the continental shelf. With the construction of a number of barrages across the Indus, the water has been diverted for power generation and irrigation purposes so much so that the water discharge into the ocean has been reduced by almost 90 per cent. Consequently, the delta area has shrunk considerably, and mangrove forest area has been drastically reduced. This reduction in Indus discharge has adversely effected the fisheries of many species of marine fish and shrimp, who rely upon the delta for part of their life cycle.

70. The Government of Pakistan has placed a high priority on the development of shrimp culture in the Indus delta, because of its potential to generate foreign exchange earnings for the country. The natural constraints are high salinities and temperature, related to the reduction in the fresh water discharge from the Indus river.

71. Philippines. The country abounds with potential areas for aquaculture with extensive inland freshwater areas, wide areas of coastline and unexploited offshore waters. Growth of the aquaculture sector is constrained by various environmental factors, most of which can be attributed to human intervention. The impact of these environmental factors are becoming critical, both in terms of threats to aquaculture production and ecological disruption.

72. Aquaculture in land-locked lakes like Laguna de Bay suffer from toxic industrial wastes, flooding, land erosion and sedimentation, mining and the deforestation of large tracts of land. Discharge of domestic and agricultural wastes is evident in Metro Manila and Central Luzon areas, resulting in eutrophication, phytoplankton blooms and oxygen depletion. Blooms of green algae have occurred in Laguna de Bay affecting cultured and wild finfish. Flooding, siltation, land erosion, land reclamation, mining, deforestation and pollution with solid waste are major causes of resource degradation in the coastal aquaculture industry and result in severe losses of production. The discharge of domestic and toxic industrial wastes into Manila Bay, and other areas near urban centres, results in severe eutrophication and phytoplankton blooms.

73. The release of excreta, metabolites and excess feeds, from cage farms in particular, has caused siltation in some major lakes. Overcrowding of fishpens and cages has resulted in reduced water flow, increased number of algal blooms and decreased dissolved oxygen levels in the lakes. Pond effluents have had similar effects on receiving waters. Pesticides and chemotherapeutants may also be carried by the effluent. In coastal areas, intensive finfish and shrimp ponds, cages and hatcheries have caused problems of eutrophication, oxygen deficiency and salinisation of water resources. Deforestation of mangrove areas and the construction of pond farms have resulted in coastal erosion, which aggravates sedimentation and reduces water flow. Drugs were massively overused in shrimp culture facilities in the early 1980s. The importation of live fish has caused the introduction of pathogens and endangered indigenous species to the point of extinction and has demonstrated the need for an effective quarantine and certification system.

74. Finfish pen and cage farms in Laguna Lake cause conflicts as they present hazards to navigation and obstruct access to fishing grounds by artisanal fishermen. There has been great competition for mangrove, swampland and agricultural areas for conversion to brackishwater ponds for intensive prawn culture (as in Zambales ricefields and Negros sugarland) resulting in loss of livelihood for mangrove dwellers.

75. Discussion: The development of shrimp farming and expansion of freshwater fish culture shows that, unless there is a means of enforcing regulations, the formulation of management schemes is to be considered a wasted effort. Local governments must have a legal framework, the resources and the will to enforce regulations. Management priorities include the enforcement of aquaculture belts or zones and formulation of local legislation with the assistance of the national government.

76. Sri Lanka. All recent developments in the aquaculture sector of Sri Lanka are related to shrimp culture. The shrimp industry is expected to contribute 60–65 % to total foreign exchange earnings from the fisheries sector. Shrimp ponds are concentrated along a coastal stretch of about 100 km.

77. There is heavy pressure on the Dutch Canal-Mundal lagoon system for extraction of brackish water for shrimp culture. This water system, which has a narrow sea outfall, seasonally acts as receiving body for wastes and water exchange. Exposure of potential acid sulphate soils during pond construction and location of farms on acid sulphate soils, have contributed to several processes that affect the general health and condition of cultured shrimps. Elevated levels of iron, manganese and aluminium in effluent water and the formation of hydrated oxides in ponds are common in farms developed on these problem soils.

78. Changes in land use in shrimp culture areas include reductions in: traditional agricultural land; space for traditional animal husbandry practices; areas for traditional small scale industries; and ecologically sensitive areas. Recently, two major issues were the retention of floods and adverse effects on the quality of salt produced. According to the symptoms observed, sub-optimal water quality conditions, adverse soil conditions and lack of quarantine facilities were directly or indirectly responsible for major shrimp disease outbreaks in the past.

79. Changes in management practices to improve the quality of inflow water and shrimp pond effluent, measures to avoid problem soils or amelioration of such soils, considerations to avoid user conflicts within the context of a coastal resource management plan is suggested for sustainable development of aquaculture.

80. Discussion: It was recognised that appropriate quarantine measures would help prevent the introduction and spread of disease pathogens. In relation to existing conflicts, it was noted that apparently the changes in resource users' rights have favoured the expansion of shrimp farming. However, it was emphasised that every proposal for large scale shrimp farming has to be assessed by an inter-ministerial scoping committee, which requires the preparation of EIAs by the prospective shrimp farmer. In contrast, small scale shrimp farmers would only have to provide the fishery authority with an initial environmental study. The general question was raised as to the usefulness of regulatory approaches versus the effectiveness of efforts aimed at the improvement of farm management practices.

81. Thailand. The statement emphasises shrimp culture in brackishwater ponds. Until about 10 years ago, when commercial production of Penaeus monodon post-larvae commenced, Thailand was mainly involved in extensive shrimp farming, culturing P. merguiensis. The farm area expanded from 4 provinces in the inner Gulf of Thailand to 23 provinces. Shrimp culture production increased from 1,590 tonnes in 1977 to 162,692 tonnes in 1992 (124,399 tonnes of which was exported). The total area under shrimp culture increased from 279,120 rai in 1987 to 470,260 rai in 1991 (1 ha = 6.25 rai). The total number of shrimp farms in 1991 was 18,998, providing employment for 114,000 people. Shrimp culture production accounted for 0.27% of GDP in 1987, increasing to 0.80% in 1991.

82. The rapid development of the shrimp culture industry has caused serious environmental impacts: (i) the mangrove area was drastically reduced, from 2,299,375 rai in 1981 to 1,128,494 rai in 1989, but it appears that only 38% of the destroyed mangrove is occupied by shrimp farms, indicating other human interventions (such as charcoal production from forest wood) have also contributed to the destruction of mangroves; (ii) shrimp pond effluent, containing silt, organic materials (left over feed, faecal and excretory wastes of shrimp), nutrients, and chemicals, has caused pollution of natural water bodies, including coastal seawater. Some 123,000 rai of shrimp farms (9,100 rai of extensive, 39,900 rai of semi-intensive and 75,000 rai of intensive farms) in five provinces of the inner Gulf of Thailand have been closed since 1989, resulting in an estimated economic loss of US $ 162.2 million. However, two years after the closure of the shrimp farms, the polluted condition of the coastal waters of the inner Gulf remain, due to the pollution caused by urban and industrial effluent which flow into the rivers draining into the shallow Gulf area; and (iii) intensive shrimp culture, under poor farm management conditions, has also caused serious shrimp diseases, due mainly to self pollution and deteriorating pond environment.

83. The nutrients in the effluent from shrimp farms might also enrich coastal seawater, increasing the production of natural fish and shellfish stocks. Production of the swimming crab is reported to have increased due to the enrichment of waters and consequent increase in feed organisms.

84. To reduce negative impacts and mitigate damage, the following actions are being taken in Thailand: (i) the total area of shrimp culture will be limited to 80,000 ha and shrimp production to 200,000 tonnes; (ii) the quality of waste effluent from shrimp farms will be controlled; (iii) farms larger than 8 ha must construct a waste water oxidation pond, (10% of the size of the whole water area and the BOD value of effluent would not exceed 10 ppm); (iv) legal action will be taken on farmers discharging bottom clay or residue from ponds; (v) the government will operate a monitoring programme of coastal waters and advise farmers; and (vi) the government will improve drainage canals and tributaries.

85. The conservation of mangrove areas is being carried out by zonation into conservation zones and economic zones and also by implementation of other measures, including suitable land-use plans for industry and coastal aquaculture, under existing regulations (Cabinet resolution of 23 July 1991). The government will undertake research on improvement of shrimp farming methods in order to maintain a sustainable level of farmed shrimp production.

86. Discussion. It has been recognised that there are limits to shrimp culture expansion due the natural capacity of the environment, and a maximum production is envisaged to amount to 200,000 tonnes. Intensive farming, however, is being promoted for social and economic reasons. Farmers are being requested to construct treatment ponds to cover 10% of the farm area. Priority will be given to training of farmers in improved farm management, and regulations on water quality control and improper use of chemicals will be enforced to penalise violators.

87. Vietnam. The country has 3,260 km of sea coast (more than 3000 large and small islands) and a complicated topography. In the coastal areas, there are lagoons, open costs, gulfs, and ponds. There were around 250,000 ha of mangrove forests in 1983 and there are around 100,000 ha of lagoon and closed gulfs, and 290,000 ha muddy littoral areas. There are a large number of rivers entering coastal waters, with one river mouth each 20 km of the coast (112 rivers mouths). There are estimated to be around 1.4 million ha of inland open waters. These environments and resources have tropical characteristics and advantages for aquaculture

88. In recent years, and especially in the Indo-Pacific region, aquaculture has been developing fast, both on a large and small scale. Aquaculture in Vietnam has also existed for quite a long time, and is characterised by diversity and self-reliance. The development of aquaculture has been based on rural folk's experiences and natural resources, resulting in differences in culture practices in the northern, central and southern parts of the country. Aquaculture production comes mainly from collective and individual activities. The State and public institutions only control about 10 percent of water areas, mostly large water areas where aquatic productivity is quite low. Aquaculture has been developing fast recently, particularly the culture of fish and shrimp for export. This development has been stimulated by increasing interest among the rural population.

89. Capture fisheries and aquaculture in Vietnam will have to supply approximately half of the animal protein for the population. The production of aquaculture currently contributes about 30–40% of the total fishery production. In addition, aquaculture offers scope for employment in production and associated industries, such as processing and feed supply, thus contributing to increasing the living standards of the people.

90. The development of aquaculture in Vietnam is based on the ecological systems of the country, for instance mangrove and coral ecosystems and littoral and estuarine environments. Hydrological factors, climate and geography, including the effects of human beings also play a role in the development of aquaculture. If production targets are met, aquaculture production in freshwater, brackishwater and marine environments will have reached 400,000 tonnes by 1995. This production includes provision for domestic consumption requirement and export. However, to achieve this production, attention will need to be given to efficient utilisation of water bodies and the preservation of the aquatic environment and sustainable use of natural ecological systems. The problems of environmental conservation are becoming increasingly acute, as exploration and aquaculture is developing at a rapid rate, and pollution problems are becoming more serious.

91. Since the mid-seventies, an environmental emphasis has been put in State plans. Thousands of hectares of forests and mangrove forests have been replanted and regulations concerning environmental preservation as well as resource management have been promulgated. There is increasing emphasis on information exchange and education of the people concerning environmental conservation. The matter of marine pollution as well as inland water pollution will become an increasingly serious matter for fisheries ecology and resources.

92. The government has given special attention to the influence of the environment on fisheries and aquaculture. However, environmental deterioration has had a serious effect on fisheries and will become increasingly important in the future. The reasons for such environmental deterioration are war, over exploitation of natural resources, lack of technology and increasing population pressures. Since the mid-seventies, research and other programmes on environment have been included in state planning. Examples include the replanting of mangrove forest and promulgation of laws relating to environmental protection. There is a growing awareness among people in the country concerning environmental protection. Nevertheless, there is a need to increase efforts to improve environmental protection of fisheries and aquaculture resources.

93. This country report gives information on the interactions between aquaculture and the environment in Vietnam. The national study includes a broad review of the environmental issues involved in aquaculture development, a more detailed case study of the environmental aspects of coastal aquaculture development in Vietnam and includes recommendations for the improved environmental management of future aquaculture development in Vietnam.

94. Discussion: It was emphasised that strategies for environmental management and resource protection are urgently needed in view of the recent opening to the market-oriented economic system and expected rapid industrial development. Rights are being ensured for the use of land and water resources by farmers. However, government administration and institutions need to be strengthened to facilitate the implementation of national policies.

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