Table 8. Fisheries production in Vietnam.
|Year||Gross total yield|
(1,000 US $)
The move towards semi-intensive shrimp culture is becoming more widespread in many localities, especially from Quang Nam-Da Nang province to Thuan Hai province. Thousands of hectares of land and waters which have not been used for a long time, or which were used with low efficiency, have now become economically productive. The application of improved science and technology would benefit aquaculture production. Areas that have potential for shrimp culture in Vietnam amounted to more than 300,000 ha and at the end of 1991, with approximately 190,000 ha already utilised, mainly for extensive culture. The mean potential yield is 150–250 kg/ha/yr. The semi-intensive and intensive culture area only covers 2,000–3,000 ha with potential yields of 1–2 t/ha/year, although in some institutions the potential yield reaches 2.5–4 t/ha/yr. An introduction to coastal aquaculture in different ecological systems, together with the main species cultured is given below.
Coastal aquaculture in the Red river delta and northern parts of Vietnam
The brackishwater ponds used for aquaculture in North Vietnam are normally of enclosed ponds in littoral areas. Fish culture mainly involves natural harvest from entrapping and holding fish. Some of the chemical characteristics of ponds can be seen in Table 9.
In the Red river area, 156 species, such as Mugilidae, Lates calcarifer, Polynemidae, Theraponidae, Bostrichthys sinensis and Leiognathidae have been recorded. The main shrimp species are Penaeus merguiensis, Metapenaeus ensis and Penaeus japonicus, which are harvested in coastal ponds. Molluscs include Glaucomya chinensis, Luteria philippinarum and Anadara granosa. Several seaweeds are cultured, but the main species is Gracilaria crassa. Until now, shrimp culture in the northern provinces has been mainly extensive, merely an enclosure or open pond which is stocked naturally and harvested. In some localities of Nghe An and Ha Tinh, ponds have been constructed for semi-intensive culture, but success has so far been limited. Low economic returns have come from semi-intensive ponds in Thanh Hoa, Ninh Binh, Nam Ha, Thai Binh, Hai Phong and Quang Ninh. In 1991–1992, the number of ponds constructed increased considerably, but the total quantity of shrimp produced did not rise and yields seems to be decreasing. Along the coast of Quang Ninh province, a cage farm cultures marine fish in cages in sheltered water. An estimated 100 tonnes were grown in 1992. The main species produced are groupers, snappers and labridae. Trash fish, captured by local fishermen (who reportedly receive a higher price for selling to the cage farms), is fed to the fish and lights are also used to attract wild fish to the cages. Juveniles for stocking cages are wild caught. The high value fish are exported live to Hong Kong aboard a special boat.
Table 9. Water quality in and outside ponds located in different regions of northern Vietnam.
|Region||Mong Lap||Cai-Yen||Yen Lap-Do Son||Red river delta||Ma river delta|
|Parameter||Ponds||Outer Ponds||Ponds||Outer Ponds||Ponds||Outer Ponds||Ponds||Outer Ponds|
|SiO2 (mg/m3)||300-100||600-300||860-200||1360-300||2160-620||2300-750||1700-450||1960- 530|
N.B. First figure refers to rainy season, second figure refers to the dry season.
Coastal aquaculture in the central part of Vietnam
The coastal lagoons in the central part of Vietnam are special areas for extensive culture. Among the species cultured are fish (Mugilidae, Chanos chanos and Siganus sp.), crabs (Scylla serrata), seaweed (Gracilaria sp.) and shrimps (Metapenaeus ensis, Penaeus monodon and Penaeus orientalis). There is growing interest in pond culture of Penaeus monodon, Penaeus merguiensis, Panulurus sp. and Scylla serrata. Shrimp yields from semi-intensive culture have reached around 1 t/ha/crop.
The brackish water lagoon region in Binh Tri Thien province possesses several advantages for seaweed (Gracilaria crassa) culture, due to the suitable ecological conditions. Ponds are commonly 5 to 10 ha in area, sometimes tens of hectares. These areas are always covered by water with suitable mean depth of 0.5–1 m. The tidal amplitude is low (0.3–0.6 m) and the water is clear, with little wind and wave action. The sediment is sandy mud and muddy sand. The only disadvantage in this area, in Quang Binh Quang Tri, Thua Thien Hue, is the climate. The western wind from Laos brings sunny and dry weather and floods are sometimes a problem for the growth and development of seaweed, in some cases causing destruction of the seaweeds. Off Da Nang, for the last two years, fish cage culture has been carried out on an experimental basis, with Seriola dumerili. This fish species lives in the coral reef. Fisher folk capture the fish fry from the wild, then rear them until the required size for export is reached. In Son Tra penisular, Seriola dumerili has been cultured in square cages of 4.5 m2 at a density of approximately 5,000 fish per cage.
The natural conditions and ecological character of central coastal localities are suitable for the fast development of shrimp culture with two main shrimp species, P. monodon and P. merguiensis. Since 1989, unsuccessful attempts have been made to culture shrimp using semi-intensive and intensive methods. Semi-intensive culture seems more suitable to the conditions and is now developing in many areas. There are now more than 500 ha used for P. monodon culture following semi-intensive culture methods and the area is growing fast. Further details of shrimp culture methods are given in Section 5. Generally, shrimp culture in Vietnam for the last two years has been developing quickly, especially in the central part. Formerly, each hectare only yielded 50–150 kg per year with extensive culture, but now some localities have managed to reach 1,000–2,000 kg/ha/year.
The central part of the country is also an important spawning and nursery area for shrimp, and the area is now the most important area for shrimp hatcheries, particularly P. monodon. The shrimp hatcheries are found in Dong Hoi (Quang Binh province), Hoi An, An Ha (Quang Nam-Da Nang province), Thi Nai, Qui Nhon (Binh Dinh province), O Loan, Van Phong, Dai Lanjh, Nha Trang, Cam Ranh (Khanh Hoa), Tuy Phong (Tuy Hoa), Phan Rang (Ninh Thuan), Phan Thiet (Binh Thuan). The shrimp post-larvae and juveniles are supplied to other parts of the country for on-growing. There are now over 200 small-scale shrimp hatcheries in the area. In addition, the successful production of Artemia in Phu Yen and Khanh Hoa has opened the possibility of supplying the requirement for shrimp production in the central part, as well as for giant freshwater prawn.
Aquaculture in the Mekong delta
In this region, coastal aquaculture has developed strongly, especially brackish water shrimp culture. According to recent data, production of freshwater fish and shrimp in Vietnam is about 170,000 tonnes (1991) of which the Mekong river delta produces about 100,000 tonnes. There are about 155 species of fish and shrimp in the Mekong delta. In the whole country there are over 190,000 ha of open waters for shrimp culture, but Minh Hai province alone has more than 60,000 ha. The areas of shrimp culture in the Mekong delta are nearly 149,000 ha, of which the area for marine shrimp culture is 135,000 ha and for giant freshwater prawn around 14,000 ha.
There are many areas which have not yet developed shrimp culture, with estimates suggesting that the possible area for shrimp and prawn culture in the provinces in the Southern part is 426,500 ha (marine shrimp culture 257,700 ha; giant freshwater prawn culture 168,800 ha). However, at the present time only 40% of this land has been brought into use. There are several methods of shrimp culture, but the most important is traditional extensive, or improved extensive system. Yields from these ponds only reach about 150–200 kg/ha/year. There is also a tendency for yields to decrease after a few years. However, there is an increasing move towards semi-intensive culture in some areas (e.g. Tra Vinh province), with yields now reported up to 1 tonne/ha/yr.
There many big river mouths and mangrove forests in the area, and an abundance of shrimp species. 25 shrimp species are classified. Popular and highly valuable species are: P. indicus, P. merguiensis, P. semisulcatus, P. monodon, Metapenaeus ensi and Macrobrachium rosenbergii. Eretmochelys imbricata is found in Kien Giang province, Phu Quoc district. Also found are Acetes indicus, Acetes japonicus, mangrove crabs (Scylla serrata) and several molluscs, such as oysters. 155 species of fish have been recorded, including Lates calcarifer, Mugilidae and Chanos chanos.
3.3 Legal framework for the environmental management of aquaculture
3.3.1 Access to aquaculture operations
Definition of aquaculture
Aquaculture, as defined in Vietnam, covers capture fisheries and aquaculture in inland waters and coastal aquaculture. Marine capture fisheries are defined as such separately. The Government of Vietnam has promulgated a number of laws relating to aquaculture. The most recent is the Ordinance on Fisheries Resources Protection (promulgated in April 1989). In addition, there are a number of other related legislative instruments:
Instructions on the prohibition of explosions for fishing in rivers, lakes and sea (April 1982).
Instructions on some urgent matters of fishery resource preservation (May 1982 and May 1984).
Decision of the Minister of the Ministry of Fisheries on the issuance of regulations and management of fishery cultured seed.
Decision of the Minister of the Ministry of Fisheries on the issuance of fishery resource preservation organisation.
Aquaculture laws and regulations
The Ministry of Fisheries organises the enforcement of these laws throughout the country. The Ministry of Science, Technology and Environment (previously the Ministry of Science and Technology) is preparing a new Environment Law which will be placed before parliament soon.
There is no national system of registration or licensing of aquaculture farms. In some areas, registration may be required (e.g. for establishment of shrimp ponds in the Ho Chi Minh City district). In general, the responsibility for coastal development and environmental protection in Vietnam is delegated to the local administration (e.g. Provincial, District). For example, the local authority in Hai Phong gives permission for coastal pond culture and levies: (i) an annual tax for the area allocated; and (ii) a production tax related to the productivity of the ponds. Under a new land law promulgated in 1993, the people have the right to long-term land leases and have the right to use their land as they wish. The responsibility for the land-leasing lies with the Provincial and District Government (People's Committee).
Special consent system
There are some restrictions on the use of lakes, rivers, mangroves or coastal areas for aquaculture, but in most cases developments proceed without restrictions, although there are a few exceptions. In inland areas, ponds may be established by individuals on private land without permission. To establish ponds on public land, permission may be required from the District, Provincial or Central Government. Procedures differ depending on the district. In coastal areas, permission to establish new impoundments (which may be built into estuaries) may be required from the local government authorities. One aim is to avoid conflicts in the use of coastal areas. The aquaculture farmer may be required to pay an annual rent to local authorities as well as a tax linked to the level of production. The rent is variable depending on the likely productivity of ponds. Around Haiphong, ponds in productive areas pay a higher rent than those in less productive areas.
Since 1975, considerable attention has been given by the Ministry of Forestry to the development of suitable legislation for the management of mangrove forests. A summary of the main features of this legislation is given in Annex I. Of particular interest, is the recent attention given in some provinces to “social forestry” management measures. For example, in mangrove forests in Minh Hai province of the Mekong delta, the Provincial government (Minh Hai People's Committee) has made a decision (Decision 64) to initiate a “Social Forestry” project. Under this project, each household in the mangrove area is allocated 10 ha of land. Of this, 75–80% of the land is for reforestation and 20–25% for other development (settlement, rice cultivation, fishpond garden etc). The contract is for 30 years, although if 75% of the land is not replanted with mangrove after 3 years, then the farmers will lose the land. The aim is to promote farmer participation in mangrove reforestation and conservation.
3.3.2 Environmental management of aquaculture
Water quality, pollution control and monitoring
There is no legislation which provides for the control of effluents discharged by aquaculture. There is no legislation specifying water quality standards for the culture of aquatic organisms, although some guidelines do exist (Annex II). There is no compulsory monitoring of water quality, however, research institutes, the Fisheries Resources and Environment Conservation Department and other institutes do undertake some monitoring of the aquatic environment.
Environmental Impact Assessment
There is no legal requirement for environmental impact assessment (EIA) for aquaculture developments. However, some EIA studies may be undertaken by State-owned aquaculture farms. The Government aquaculture research institute in the Mekong delta is promoting environmental impact assessment for new shrimp farms. Some larger external funded projects (e.g. two UNDP/World Bank shrimp cum mangrove projects in the Mekong delta provinces of Ben Tre and Minh Hai have prepared environmental impact assessments).
Control of the movement of fish
The Animal Quarantine and Veterinary Inspection Division of the Ministry of Agriculture is responsible for inspecting and certifying live fish and shrimp imports and export shipments. However, it is usually specialist fish pathologists from the Ministry of Fisheries that are given the task of examining the shipments. In the Ordinance on the “Conservation and Management of Marine Resources”, it is stated that the Ministry of Fisheries have the responsibility for decisions concerning the introduction and breeding of new species in Vietnam.
Control of toxic or hazardous substances, or pharmaceutical preparations
There are no controls on the use of chemotherapeutants on fish farms in Vietnam. Likewise, there are no controls on the use of pesticides and other biocides in aquaculture.
The Ordinance on the “Conservation and Management of Marine Resources” also states that it is prohibited to exploit fish spawning areas and where large numbers of fry accumulate. However, protected areas have not yet been defined. Some wetlands have been designated as protected areas.
3.3.3 Compliance control
No information is available on this subject, however, it is recognised by officials of the Ministry of Fisheries that enforcement of the fisheries laws needs to be strengthened. The recently established Fisheries Resources and Environment Conservation Department has responsibility for enforcement of fishery laws and the development of suitable guidelines for protection of the fishery environment. The Department has sub-headquarters in each of the 26 provinces. There is also the recognition that the promulgation of laws relating to the conservation of mangrove areas are not entirely effective, as the conversion of mangrove areas to shrimp ponds is still continuing on a large scale in the southern part of the country, particularly in the Mekong delta.
3.4 Institutional framework
The Ministry of Fisheries has the overall responsibility for aquaculture development in Vietnam, however, the Provincial Fisheries Department's and District governments also have the responsibility for the planning and monitoring of aquaculture development at the provincial and district level. There are several institutes under the Ministry with different responsibilities related to aquaculture and the environment. The environment in general is the responsibility of the newly formed Department of Natural Resources and Environment under the Ministry of Science, Technology and Environment. The Department co-operates with the Ministry of Fisheries on matters relating to aquaculture, capture fisheries and environment. In addition, there are some other organisations involved, including:
Vietnam Fishery Association;
Vietnam Export Shrimp Culture Association;
Marine Science and Technical Society of Vietnam;
Environment Preservation Society of Hai Phong;
Nature Conservation and Environmental Protection Association.
In the Ministry of Fisheries, the newly created Fisheries Resources and Environment Conservation Department has responsibility for the management of fisheries resources and environmental management in relation to fisheries and aquaculture. The following gives information on some key issues involved in aquaculture:
|Research Institute for Marine Products (RIMP), Hai Phong.||Coastal aquaculture in the northern part of Vietnam and marine fisheries resource assessment.|
|Institute of Fishery Economics and Planning, Ministry of Fisheries.||Management, short and long term fishery sector planning, some research.|
|Research Institute for Aquaculture, No.1, Dinh Bang, Ha Bac province.||Research and management of freshwater aquaculture and inland capture fisheries in the northern parts of Vietnam.|
|Research Institute for Aquaculture No. 2, Ho Chi Minh City.||As above, but with responsibility for the southern part of Vietnam (including coastal aquaculture).|
|Research Institute for Aquaculture No. 3, Nha Trang, Khanh Hoa province.||Research and management of aquaculture in the central part of Vietnam.|
|Fisheries University, Nha Trang.||Training.|
4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW
There are several environmental aspects that may constrain the development of the aquaculture industry in Vietnam. The quality of certain waters is deteriorating due to industrial, agricultural and urban developments and fisheries resources are already said to be in gradual decline. Pollution by aquafarms themselves could exacerbate the situation, and there is therefore a need to legislate on matters of conservation and educate farmers on good management practices. However, at present, Vietnam has few resources for applied research into problems of pollution and environmental degradation and there are little data available. Vietnam has carried out studies of organic matter, nutrients, oil, oil products and heavy metal pollution in some coastal areas. The following gives a general review of the main information available.
4.1 Impacts of external environment on aquaculture production
4.1.1 Inland aquaculture
In general the quality of water of the rivers in Vietnam is good, however in the estuaries, due to the influence of tides, river water is affected by seawater intrusion near the coast. The major environmental problem associated with inland aquaculture is water pollution. There are a lack of data on which to base good assessments. Nevertheless, the following gives an outline of information available.
Water pollution and inland aquaculture
Vietnam is quite long in length but narrow in width, in some parts it is only 40–50 km wide. There is an abundance of rivers, streams and canals with many branches, which makes the river and sea systems closely connected. What happens in the upper river can be seen within a short time in the lower river and river mouth. Vietnam has an estimated 376 km3 of annual renewable water resources (5,600 m3 per person) of which about 5 km3 are utilised. Domestic use accounts for 13% and industrial use 9%. Some of the major problems are erosion and siltation and water pollution from urban development, industries and agriculture. Although specific data are lacking, there are several examples of poor water quality, particularly near large urban centres. Around Ho Chi Minh City, unregulated discharge of domestic and industrial waste water into the Tham Luong channel leaves it heavily black and with a high concentration of organic matter. COD sometimes reaches 596 mg/litre and BOD5 is 184.5 mg/litre. The dissolved oxygen content is usually zero.
In the northern part of Vietnam, there are a great number of water bodies with poor water quality such as rice fields, lakes and ponds full of water for years and river and streams as well. For instance, the water of To Lich, and Kim Nguu rivers are very dirty and the dissolved oxygen content is very low and occasionally zero. The BOD5 content is high at over 50 mg/litre, NH+4 is over 10 mg/litre, NO-2 is also high. H2S is approximately 30 mg/litre. Again, the problem appears to be unregulated discharge of domestic and industrial waste water.
In Lam Thao district, Vinh Phu province, in the dry season, the river branch flowing across the city and factories is heavily polluted. The pH is very low (4.0), free acid is high and iron content and organic substances, as well as NH+4 and NO-2 are high. The effects of water pollution can also be seen at Phong-Chau (Vinh Phu province), where several parameters are higher than the permissible levels allowed for fish culture. Phenol content varies from 0.015–0.03 mg/litre (mean value is 0.022 mg/litre-permissible phenol content in the water allowed for fish culture is 0.02 mg/litre). In some sampling stations, the iron content is higher than permissible. The iron content in the water of the river varies from 1.05–1.52 mg/litre (mean value 1.17 mg/litre), while the iron content permitted in water for fish culture is under 0.05 mg/litre. Generally speaking, water quality in this area of the river is poor (Table 10) and the total quantity of potentially harmful substrates discharged from the main river systems is considerable. The results of a calculation of the loading of pollutants in four large river systems in Vietnam is given in Table 11.
Impacts of pesticides on inland aquaculture
The overuse and abuse of pesticides may be a common problem in freshwaters. Rice farmers are using mainly organophosphate and carbamate insecticides, but organochlorines are still in use. The organophosphorus and carbamates can be acutely toxic to fish and invertebrates, but tend to be less persistent in the environment. Some, however, are highly toxic to crustaceans and thus are potentially a significant problem for integrated rice-Macrobrachium culture. The organochlorines are still being used on rice and other crops (2–4 D as a rice field herbicide, lindane and BHC on orchard crops). Most organochlorines are toxic and highly persistent in the environment, posing a threat to aquatic animals, farmers and consumers of aquatic products. Most chlorinated hydrocarbons have been banned in developed countries, but are still used in Vietnam because of their low price and availability.
The impact of pesticide usage in Vietnam is difficult to assess, but long term effects on fisheries and aquaculture are potentially serious. There are numerous reports of decreased fish production and severe local fish and Macrobrachium kills in ponds and canals following the spraying of pesticides on rice, which indicates that such hazards need to be considered as a potentially serious problem for fisheries in some locations. In some areas, aquaculture and fisheries may be incompatible with agriculture because of heavy pesticide use (e.g. triple rice cropping areas, Macrobrachium integrated with orchard crops). There is evidence from studies in other countries that integration of fish with rice may reduce pest infestation. Some studies in Vietnam also suggest that stocking of Macrobrachium with rice resulted in a 15% increase in rice yield and 10% reduction in fertiliser requirement. Thus, more sustainable and environmentally sound integration of aquaculture and agriculture may be possible, at least with rice crops.
Table 10. Water quality of the Red river along the Vinh Phu industrial section.
|Parameter||Sample 1||Sample 2||Sample 3||Sample 4||Sample 5|
|Dissolved oxygen (mg/l)||7.5||7.2||6.8||5.2||7.8|
|Suspended solids (mg/l)||1250||1545||1425||1110||1025|
|Faecal coliforms (MPN/100 ml)||1200||1550||1350||1400||1100|
|Faecal Streptococcus (MPN/100 ml)||1250||1150||950||1050||1300|
Table 11. Gross total load of pollutants in four river networks (tonnes/year).
Source: Do Hoai Duong, 1991-Centre for Management and Air, Water Environment Control, Hanoi).
Farmers appear to be aware of some of the problems associated with the use of toxic pesticides. In the Mekong delta, farmers may drain water containing fish and prawn to a ditch before spraying the rice crop. In this way, impacts on aquaculture in rice fields may be reduced.
4.1.2 Coastal aquaculture
The north-east monsoon season occurs from October to March affecting fisheries in the Red river delta region. Typhoons and strong winds during this period can cause physical damage to aquaculture. The rainy season in the central region takes place from September to December, often causing flooding. The Mekong delta region is rarely effected by typhoons, but the south-west monsoon season from April to September brings rain and sometimes serious flooding. These physical factors can have a severe impact on aquaculture.
In 1992, the coastal provinces in the central part of the country suffered extremely heavy typhoon damage from tropical cyclone “Collen”. The large tidal waves associated with strong winds caused damage to over 15,000 ha of rice field, shrimp ponds, salt farms and fruit farms in Soc Trang province. There are reports that destruction of coastal mangrove forests (which provides some protection of coastal land) has increased the damage to aquaculture ponds caused by typhoons. Replanting of mangroves in some provinces has also provided some protection for aquaculture ponds (shrimp and crab) from typhoons.
The development of irrigation works, hydroelectric projects and river control schemes are reducing fishery resources and are reported to be reducing the water area available to aquaculture, however, no details are available. Sedimentation in some coastal aquaculture ponds is a problem. Around Hai Phong, farmers report problems related to the sedimentation of Gracilaria ponds. In the Mekong delta, farmers cultivating shrimp alternatively with rice are reporting problems with pond siltation. Such ponds require regular excavation and in some areas excessive siltation has resulted in ponds being abandoned for aquaculture. In such cases, silt deposition may raise the optimal height for efficient tidal water exchange. In the Mekong delta, farmers may abandon silted ponds and move to a new area, leading to patterns of “shifting shrimp cultivation”.
Coastal water quality and aquaculture
In general, the coastal waters of Vietnam are fairly clean and most water quality parameters do not exceed permissible limits. Surveys of coastal waters by the Research Institute for Marine Products show that water quality is good in most areas. However, areas around river mouths and large towns of industrial development are subject to some pollution problems. Such problems are likely to increase in the future. The metal content of the water is not high. However, in some locations there are problems with oil pollution. In the seawaters of Vietnam, there is increasing oil and gas exploration and exploitation. Annually, there are leakages to the marine environment (oil transportation involves 20,000 tonnes annually). The number of oil spills could increase substantially in the near future. Examples are seen in the Vung Tau and Halong bay area (Table 12).
Table 12. Analytical results of dissolved oil content in seawater (8 sampling stations, 11 samples).
|Mean (mg/l)||Max (mg/l)||Min (mg/l)|
Source: Research Institute for Marine Products.
In four surveyed stations from Quang Ninh province to Thai Binh province, the concentration of some metals, such as copper, exceeded the permissible concentrations (0.01 mg/litre), reaching concentrations of 0.017–0.048 mg/litre of dissolved copper. Mercury contamination may prove very harmful to aquatic organisms, one third of the samples exceeded permissible concentrations. In the water layer near the bottom of Bach Dang and Thai Binh river mouths it was 0.005 mg/litre and in other stations it is now 0.0002 mg/litre. In some areas, Fe2+ exceeded the permissible concentration (0.50 mg/litre), reaching Fe2+ concentrations of 1.20–1.65 mg/litre. The results are summarised in Table 13. In general, the effects of these contaminants on marine life are poorly understood and there is a need to expand such surveys to make a better assessment of the impacts of marine pollution in Vietnam, as well as to develop strategies for controlling problems. Some additional information on water quality is shown in Table 14.
Table 13. Mean, maximum and minimum values of four metals in seawater in the estuaries and coastal areas of Quang Ninh-Thai Binh.
|Metal||Mean (mg/l)||Maximum (mg/l)||Minimum (mg/l)|
Source: Research Institute for Marine Products.
Table 14. Coastal water quality in some regions (units: mg/l).
Source: Research Institute for Marine Products.
In 1984, a red tide occurred in Hai Long Bay and around Cat Ba Island in northern Vietnam causing damage to fisheries in the area. There is no evidence that red tides have yet affected aquaculture development.
4.2 Contamination of aquaculture products
There is no information on the contamination of aquaculture products.
4.3 Impacts of aquaculture on the environment
4.3.1 Inland aquaculture
Impacts on water quality
There are some reports that the heavy use of organic fertiliser in pond culture can pollute the water outside the culture system, and the use of inorganic fertilisers causes nutrient enrichment of the environment. However, no quantitative data exists on the subject.
The following chemotherapeutants are commonly used in Vietnamese aquaculture: copper sulphate (CuSO4), malachite green, potassium permanganate solution (KMnO4), salt, Melia azedarach leaf, chloramphenicol, tetracycline, streptomycin and sulfanilamide, but contamination of the environment with these agents is not as yet considered a major problem. Rotenone is a drug of vegetal origin that is used for eradicating predator fish, but the impact of this and other chemicals on the environment has not been studied.
Interactions between aquaculture and native species
The collection of wild Pangasius sp. and Macrobrachium sp. fry in the south and other native fish species in the north may have a detrimental effect on natural river stocks, but the effects have not been studied. Artificial propagation should be encouraged as a countermeasure. Certain other aquaculture practices have been identified which have potential for some adverse impacts on capture fisheries resources, although there are insufficient data for a reliable assessment. Feeding of fish to cages in Vietnam may be diverting potential protein sources from the rural poor to high value export species.
There are several species which have been introduced into Vietnam for aquaculture. There are no reports that these species have had any adverse impact on the environment. In the southern part of the Mekong delta, Oreochromis mossambicus, an introduced fish species, is common in the catch from extensive brackishwater ponds. On the positive side, aquaculture development also provides an additional feed source for mammals and birds.
Impacts on public health
Ba and Chanh (1988) report that the practice of feeding fish with nightsoil contributes to the pollution of canals and the main Mekong/Bassac river water with faecal coliform and Streptococcus (but direct release of nightsoil into canals, i.e. not via ponds, could pose a worse risk). Little other data were available on public health issues and aquaculture in Vietnam.
Sewage fish and integrated fish culture
Vietnam has widely adopted the traditional integrated aquaculture in what is known as the VAC system (from the Vietnamese words for orchard, pond and pigsty). This system promotes the recycling of potentially polluting organic matter and nutrients. Near Hanoi, there is also a well developed system of fish culture based on sewage and other domestic waste waters from Hanoi. The system produces fish protein from potentially polluting wastes (an example of a positive impact on the environment). However, the long term sustainability of this system may be affected by the discharge of industrial wastes into the water supplies of these fish ponds.
Social conflicts and aquaculture
In some areas, such as the suburbs of Hanoi, inland aquaculture faces competition for land, fertiliser and feed with rice growers. There is also competition between fish farmers for suitable water sites. Also, the use of fertilisers in fish farms located near tourist centres (such as Ho Tay) is reported to have a detrimental effect on the environment of these areas. No appropriate measures have been suggested with which these situations can be alleviated.
Freshwater cage culture
In the Mekong delta, cage culture is practised along the Bassac river in An Giang and Dong Thap provinces. The main species are Pangasius bocourti and Pangasius nasutus (90% of production). The major species cultured in cages in Vietnam is Pangasius bocourti which requires good water quality. In contrast, P. hypopthalmus is the major species of the genus cultured in Cambodia further upstream in the Mekong river system because it can tolerate the poorer water quality which occurs during periods of limited water flow in the dry season.
The following environmental problems are reported with cage culture:
The intensive cage culture practised on the Bassac river at Chau Doc produces waste materials which can cause water pollution. The main wastes are uneaten food (studies have shown that the use of trash fish, a component of the feed used at Chau Doc produces high pollutant loads), faeces, and soluble metabolites, such as ammonia. These organic and inorganic wastes can cause dissolved oxygen depletion and increased levels of BOD, solids, nitrogen and phosphorus in the vicinity of culture operations.
Chemicals used for disease treatments may also be released into the natural environment. Various chemicals are used to control fish disease outbreaks in the cages (streptomycin and chloramphenicol have been reported). The antibiotics used are a threat to product quality (residues in fish flesh) and human health (development of resistant strains, aplastic anaemia in the case of chloramphenicol). The use of such compounds should be avoided.
Cage fish farming at present seems unlikely to cause significant widespread pollution. However, localised pollution in areas with large concentrations of cages (e.g. Chau Doc) may be significant at times of low flow, i.e. when there is less water to flush away wastes. There is evidence that outbreaks of fish disease (ulcerations, septicemias) are common in cages at Chau Doc and it is likely that water quality deterioration plays a role in these outbreaks. Such problems might be avoided if cages were not crowded. Improved husbandry techniques and avoiding overcrowding at cage sites would help reduce disease problems and the need for such chemicals (prevention is better than cure).
So far, there are no planning restrictions on developments related to environmental factors. Further expansion of cage farming on the Bassac or Mekong rivers, proposed by the Ministry of Fisheries should be preceded by an assessment of potential environmental impacts, and a suitable survey to determine the number of cages and sustainable stocking densities. Such planning would avoid the future problems of disease and water pollution that will inevitably accompany unplanned and uncontrolled intensification and expansion of fish cage culture. Uncontrolled expansion could also put at risk the present cage farming operations.
4.3.2 Coastal aquaculture
Physical effects of coastal aquaculture
Coastal shrimp and finfish pond culture has caused salinisation of soils and water in some areas. However, the embanking and encirclement of land for conversion into culture ponds and rice-fields can prevent the discharge of fresh water. Although such problems have been seen, the impact on the environment has not been determined.
Impacts on coastal water quality
There are some anecdotal reports that shrimp farming has had some impact on coastal water quality. No studies have been carried out for other culture systems. The information available on shrimp farming is reviewed in Section 5 of this report.
Impacts on coastal mangrove forests
Deforestation and reduced water flow have also identified as problem caused by coastal fish farms. Mangrove forests are the main nursery areas for high value marine fish species and detritus from mangroves are carried to coastal areas to support other fish and shrimp populations. Furthermore, the forests protect the alluvial grounds from erosion, restrict the damage caused by typhoons and prevent the penetration of seawater into inland areas. These important interactions are being threatened by the over-exploitation of mangrove areas, including exploitation for brackishwater aquaculture development. This aspect is discussed in more detail in Section 5.
To develop suitable strategies to reduce the impact of shrimp farming on mangroves, the Ministry of Fisheries has (in co-operation with the Ministry of Forestry) initiated a research project on the sustainable utilisation of mangroves for shrimp farming. The aim of the research is to define some of the problems, and develop suitable strategies for the development of shrimp farming in areas with mangroves. The research covers the northern, central and southern parts of Vietnam.
Interactions between aquaculture and native species
Fish are captured from saline forest areas for use in aquaculture and the conversion of coastal lagoons into fish ponds has resulted in the reduction of spawning and nursing grounds for natural fish species. The ecology of these areas should be studied and regulations for their conservation drafted. Artificial propagation should be encouraged and small and medium scale fish hatcheries developed. Cage culture of groupers relies entirely on the natural seed supply. The main species involved are Epinephelus bleeker, E. tauvina, E. megachir and E. fasciatus. The effect of collection of wild marine fry for aquaculture has not been studied. The culture of shrimp in Vietnam also relies largely on wild shrimp post-larvae. The impact of this demand on wild fisheries has not been studied.
Social conflicts and aquaculture
Competition for coastal land area exists between fish, shrimp and seaweed farmers and rice farmers. There are also conflicts between mangrove conservationists, and those who would exploit these areas. These conflicts arise because of a certain lack of control over exploitation of coastal land areas in Vietnam.
Marine cage culture
Marine cage culture is a new industry in Vietnam. At present, there are an estimated four sites owned by one Vietnam-Hong Kong joint venture company operating in Quang Ninh province. There is also at least one site in Nha Trang. The farms culturing marine fish in cages in sheltered water along the coast of Quang Ninh province, produced an estimated 100 tonnes in 1992. The main species produced are groupers, snappers, labridae and some other minor species. Feed is trash fish captured by local fishermen who reportedly receive a higher price for selling to the cage farms (lights are also used to attract wild fish to the cages). Juveniles for stocking cages are wild caught. The high value fish are exported live to Hong Kong aboard a special “well-boat”. This is a new venture, but already some environmental problems have been reported, including:
Typhoon damage: In 1992, a large typhoon caused significant damage to cages and some loss of stock. The cages were protected to some extent by their sheltered location among the limestone outcrops common in Quang Ninh province. During the typhoon, 1,000 fish were reported to have died.
Self-pollution: The caged fish are fed trash fish which leads to high wastage. The cages are sited in areas with limited water exchange. Farmers report that in hot summer weather mortalities occur. As there has been no study, it is difficult to ascribe causes, but it is likely that self-pollution plays a role. Disease outbreaks of unknown disease also occur around this time. Treatments are with unknown antibiotics (imported from Japan via Hong Kong), reported to be partially successful.
5. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: IN DEPTH STUDY
5.1 Coastal shrimp culture in Vietnam
As outlined in Section 3, the natural conditions and ecological character of central coastal localities in Vietnam are suitable for the rapid development of shrimp culture with two main shrimp species, P. monodon and P. merguiensis. Semi-intensive culture seems more suitable to the conditions and is now developing in many areas. There are now more than 500 ha used for P. monodon culture following semi-intensive culture methods. Table 15 gives some details of the shrimp culture methods. Generally, shrimp culture in Vietnam for the last two years has been developing quickly, especially in the central part. Formerly, each hectare only gained 50–150 kg per year with extensive culture, but now some localities have managed to reach 1,000–2,000 kg/ha/year.
Table 15. Shrimp culture systems for production of marketable sized shrimp.
|Stocking density (PL/ha)||3000–3500||10,000–20,000||50–100,000||150,000|
|Age at stocking (PL days)||40–50||40–50||20–25|
|Feed source||Natural||Natural||Natural & Supplementary||Supplementary|
|Culture period (days)||150–150||120–150||110–130||110–130|
|Average pond area (m2)||50,000||20,000||2,000||1,000|
|Water exchange||Tide||Tide||Tide, pump||Pump|
|Economic return (US $/ha)||1000–2500||2500–5000||5000–10000||12500–25000|
|Fry Source||Natural||Natural & Artificial||Artificial||Artificial|
Coastal shrimp farming is growing fast in Vietnam, in terms of pond area and through intensification of the culture industry. Already, several impacts related to the development of shrimp farming have been reported and there is a need to clearly define impacts and develop appropriate strategies for the development of an environmentally sound and sustainable industry.
5.1.2 The environmental impacts of shrimp culture
Positive impacts of shrimp culture in coastal areas
It is important to emphasise the positive impacts of shrimp farming in coastal areas of Vietnam. These include:
However, these advantages may be offset by environmental impacts associated with development, many of which are similar to those reported in other countries of the region. At present, the information required for an overall assessment of both the positive and negative impacts is not available. Such a study is urgently needed.
A positive environmental impact associated with shrimp culture can be found in the Mekong delta. In areas with intrusion of saline water in the dry season, there is a well developed farming system where farmers grow shrimp in the dry season and rice in the rainy season, when freshwater becomes available. The culture of shrimp in the dry season allows a build up of fresh silt on the bottom of the pond, which when flushed with freshwater at the beginning of the rainy season allows a successful rice crop to be grown. Production from such systems can be high, with reports of cumulative shrimp yields of 690 kg/ha/year (Xuan et al., 1984). Farmers have learnt that keeping the soil wet by culturing shrimps (and capping the soils with fresh silt) is a means of successfully culturing rice in potential acid sulphate soil areas (farmers allowing the soil to dry out during the dry season suffer acidity problems and low yields of rice -- an unusual positive environmental impact of shrimp culture). Unfortunately, these systems rely on an abundance of wild shrimp larvae, which are becoming scarcer. The economics of these systems operated using stocked (hatchery-reared post-larvae) would be worthy of examination, (i.e. are the systems sustainable with an anticipated shortfall in wild shrimp post-larvae and what is the effect of stocking on economic returns). The following gives further information on other impacts of coastal shrimp culture on the environment.
In the central part of Vietnam, there are over 100 small-scale hatcheries producing P. monodon. It is reported that the effluent from the shrimp hatcheries is indiscriminately released into waterways, causing pollution of other farmers' waters supplies. The result appears to be an increased incidence of disease problems in the hatcheries. The Ministry of Fisheries has initiated a project “Clean Hatcheries” to develop strategies to reduce pollution of water supplies and produce disease free shrimp stocks. Proper sterilisation (e.g. using chlorine) of the water supply is required to grow shrimp successfully.
Mangrove removal for shrimp farming
There is a high degree of government and private sector interest in shrimp culture because of the export potential for shrimps. Traditional shrimp culture has always taken place in mangroves, but since 1986 there appears to have been a major acceleration in the use of mangrove resources for shrimp culture. In some instances, the mangrove forest is cleared completely and the income obtained from selling the wood invested in pond construction. Deforestation is recognised as a major problem in Vietnam, with country-wide deforestation occurring at a rate of 150,000 to 200,000 ha per year, the net effect of which has been a reduction in forest cover from 42.3% in 1960 to 21.8% in 1988, and continuing. In the past, mangroves covered an estimated 400,000 ha of coastal land in Vietnam. This area was dramatically reduced during the second Indochina war. Following the end of the war, reforestation was carried out. However, in 1983 there were estimated to be around 252,500 ha of mangrove forest left, most of which was in the southern Mekong delta. Much of this coverage was of secondary shrub growth with some natural forests and plantation (Table 16). Unfortunately, since this time there has been further loss of mangrove forest, particularly since 1983 in the Mekong delta. Most of the comments below refer to the Mekong delta.
In the Mekong delta, mangrove forests originally occupied an estimated 250,000 ha of delta coastal land. An estimated 124,000 ha of mangroves were lost during the war (Rhizophora, economically the most important mangrove tree, is reported as being particularly sensitive to the defoliant chemicals used). Since 1975, the extent and quality of the mangroves have decreased further due to timber and firewood exploitation, expansion of paddy land and shrimp farming and in 1988, only 93,502 ha remained in the delta, mainly in Minh Hai province (77,682 ha) (Table 17). Estimates of losses in the delta due to shrimp farm development differ, from 60,000 ha of mangroves cleared between 1985 and 1988 to an annual rate of 3,000–5,000 ha (Hong and San, 1993). The true extent of mangrove deforestation and degradation is probably unknown.
Table 16. The extent of mangrove forests in Vietnam in 1983 (from: Hong and San, 1993).
|Coastal area||Total area (ha)||Natural trees (ha)||Shrub forest (ha)||Plantation (ha)|
Table 17. Mangrove forest area in the Mekong Delta (from NEDECO, 1990).
|93,502||77,682||Minh Hai province.|
|3,765||Kien Giang province.|
|2,691||An Giang province.|
|2,183||Tien Giang province.|
|1,150||Cuu Long province.|
|6,031||Ben Tre province.|
5.1.3 Environmental impacts related to mangrove removal
The continued exploitation of mangroves will have negative impacts on coastal capture fisheries and aquaculture. However, detailed information on problems is lacking. Some gross impacts are already evident, with increased coastal erosion in Tien Giang, Ben Tre, Cuu Long and Minh Hai linked to mangrove deforestation. Impacts on fisheries are not documented but, given the importance of mangroves to coastal fisheries, loss of finfish, crustacean and mollusc fishery seems inevitable. The following problems are reported by Hong and San (1993):
Mangroves are recognised as providing important support in maintaining fish resources as nursery grounds for penaeid shrimp. There is some evidence that the availability of shrimp larvae to stock ponds has decreased in the Mekong delta. However, the cause may also be related to increased fishing pressure.
Mangroves are also important habitats of mud crabs (Scylla serrata) an important export crop. The population of mud crabs is reported to be decreasing in several areas along the coast. The reasons are thought to be over-exploitation and conversion of mangrove habitat to other land uses.
Mangroves create a buffer zone against storms and intrusion of saline water. In some areas, removal of mangroves has led to shrimp ponds being made more vulnerable to storm damage in typhoon areas. In others, the construction of dykes and embankments for shrimp farming has led to hydrological changes in coastal areas. In 1991, more than 2,000 ha of rice fields at Can Gio district, Ho Chi Minh City were damaged by saline water intrusion.
Increased malarial incidence in some coastal areas is being related to the clearing of mangrove forests, which can lead to increased number of stagnant pools for breeding of mosquito. In an undisturbed mangrove forest, the mosquito habitat is inundated by seawater.
Although described in general terms, and undoubtedly serious, these various impacts have yet to be quantified in economic terms.
5.1.4 Low production of cultured shrimp and reasons for shrimp farm failure
In spite of the increase in area, production from shrimp ponds remains very low. There is also evidence that production from ponds has decreased with time, for several reasons, including:
Unsuitable siting of ponds;
Reductions in supply of post-larvae;
Lack of pond production;
Lack of predator control.
Some of these impacts are likely related to the removal of mangroves themselves. Loss of mangroves combined with intensification has the potential to reduce the availability of wild shrimp post-larvae for stocking ponds, loss of shrimp broodstock, and possible water quality deterioration, resulting in disease and shrimp kills. In the long-term, loss of mangroves will likely lead to a reduction in the economic viability of traditional extensive shrimp farming systems (because wild shrimp post-larvae will no longer be available to stock the ponds) and heavier reliance on hatchery stock. There is evidence that this is already happening, with reports of a decline in numbers of post-larvae entering ponds.
Experience indicates that in the first year the production of ponds is reasonable (250–500 kg/ha/year), but after several years the production starts to decrease either because of a decrease in numbers of post-larvae or loss of pond nutrients. Sampling the intake water of several farms and comparison of the results with the available data from 1983 is reported to confirm a reduction in post-larvae. The reduction of shrimp is thought to be due to the fact that mangrove areas, which serve as nursing place for larval shrimps, are destroyed and replaced by shrimp ponds. Between 1986 and 1988, there was an increase in pond area from 72,200 ha to 123,371 ha, but a corresponding increase in production of only 21,453 tonnes to 22,668 tonnes. This production is equivalent to a decrease in areal production from 297 kg/ha to 153 kg/ha, a trend which probably reflects these environmental changes, and one that seems incredibly wasteful of natural resources.
5.1.5 Impacts of shrimp farming on water quality
There have been fewer studies of the impacts of shrimp farming on water quality. Some studies have shown that water quality in extensive ponds and canals in areas with large numbers of extensive ponds is poorer than in areas without pond development. However, further studies are needed on this subject.
5.1.6 Environmental legislation and management of shrimp farming
The responsibility for the coastal development and environmental protection in Vietnam is delegated to the local administration. However, it appears that the culture of shrimps has proceeded without proper consideration of the environmental impacts. In Minh Hai province, the People's Committee of Minh Hai has formulated a number of decisions, regulations and instructions to control the exploitation of mangrove areas for shrimp culture. On February 17, 1992, the Ho Chi Minh City's Agricultural Service issued announcement no. 109/LN-TB prohibiting mangrove forest clearance for the purpose of shrimp pond construction. This announcement also required registration of all units and households building shrimp ponds in mangroves and approval from the Agriculture Service for ponds greater than 1 ha.
5.1.7 Community participation in integrated shrimp-forestry
Some actions have been taken to initiate organised management of mangroves in Vietnam, particularly in Ho Chi Minh city and Minh Hai province. Participatory mangrove and fishery projects were initiated in Minh Hai province in 1984. Mangrove and Melaleuca forests are leased out to households under clearly spelt out benefit and responsibility sharing mechanisms for planting, management, protection and harvesting of tree resources. Under the scheme, each household receives 5–10 ha of forest land, 20% of which can be utilised for agriculture, horticulture and shrimp farming, while an additional 5% can be utilised for housing and kitchen gardens. The remaining 75% is to be planted with suitable forest species. 80% of the benefits are accrued to the leasees while the Government gets 20%. Up to 1993, 5,700 families have been allocated 28,100 ha of land. Apart from wood, the major product is shrimp (or fish). The Government does not share in this harvest and the entire production belongs to the participants.
The above scheme has been mainly used in areas which are barren and depleted of tree stocks. Allocation of land in fully stocked forests is also practised. However, in such cases, the allocation of forest areas has resulted in additional loss of forest cover because of conversion of forest to shrimp ponds. This is partly because the participants are more interested in shrimp farming than in forestry (and presumably can get more short-term economic benefit). Each household received 5–7 ha of degraded forest land of which 70–80% is meant for Rhizophora farming with a density of 20,000 trees/ha. The remaining 20–30% is reserved for shrimp farming. During the first two years, the farming systems yielded about 250 kg/ha/yr (in the 20–30% reserved for shrimp farming). After 4–5 years, the shrimp production decreases to 100–170 kg/ha as the mangrove canopy closes. This type of approach has helped to slow the rate of mangrove conversion to shrimp ponds. However, further development and refining is required.
The present state is that further models are being developed to integrate forestry with fishery. The key will be how to generate economic benefits of both shrimp and mangroves together. Incentives are given to farmers to maintain the shrimp-mangrove “model”. On no-forested areas, farmers are exempted from taxes for the first year. Such incentive schemes may require further development to optimise these systems.
5.1.8 The environmental management of shrimp culture in Vietnam
Apart from the above mangrove-shrimp systems, there is a need to explore other ways to integrate shrimp farming into the coastal areas in an environmentally sound manner. There is a high degree of awareness in the government authorities in Vietnam of the environmental problems associated with shrimp farming intensification in other countries in Asia. Efforts are required to ensure that shrimp farming is better integrated into the coastal system in Vietnam through more effective planning and monitoring measures, and to improve the production from existing systems without damaging the culture environment.
6. PRIORITIES FOR DEALING WITH ENVIRONMENTAL PROBLEMS
This section identifies priorities for the Government and the private sector to deal with present environmental problems and prevent further problems affecting aquaculture in the future. A general survey of aquatic resources is needed to ascertain the potential for further development of the industry, paying particular attention to environmental fluctuations caused by fishing and other activities and the impacts of environmental change on aquaculture. From 1959–1985 a survey of fishery resources was undertaken, but this should be widened to include the whole country, taking a holistic view of all the related factors. A scientific base such as this is needed in order to preserve the ecology of commercial fishery resources. Assistance from regional and international organisations such as NACA, UNDP and FAO would be useful in carrying out these tasks. Some more specific actions are given below:
Prohibition of the use of destructive fishing methods is important for the conservation of fishery resources;
Efforts are being made to further develop artificial seed production to reduce pressure on natural fishery resources. This includes both freshwater and marine species. In order to maintain and develop marine shrimp resources, it is necessary to limit the fishing effort on small shrimps and fry with barrier, drift nets in the estuaries and seawaters within 10 km of the coast; with an aim to minimise the small shrimp killed;
To control water pollution, there is need for early completion of regulations for the prevention of pollution, particularly oil pollution, which is regarded as a potentially serious threat to coastal waters;
The following measures have been taken to conserve areas of coastal mangrove forest:
There has been some success in community based approaches to aquaculture management, as noted for shrimp culture in mangrove areas. One other example is to be found in reservoir management in the southern part of Vietnam. Here, some reservoirs (Song Da, Thac Ba) have been more successfully managed following allocation of different “zones” to villages surrounding the reservoirs. Although such approaches require further refining, the use of “community based approaches” to the management of resources for aquaculture development shows good promise for solving some of the environmental problems related to aquaculture development.
7. FUTURE AQUACULTURE DEVELOPMENT
In the future, closer attention will be need to be given to environmental aspects of aquaculture development. This will be necessary to protect aquaculture from adverse environmental impacts and to reduce impacts of aquaculture on the environment. The following recommendations are given:
There is a need to prepare an integrated strategy for the protection of environment in Vietnam. This strategy should be based on a clear understanding of the causes of pollution and the impact of this pollution on fisheries and aquaculture. Thus, research is required on the causes and effects of environmental problems faced by aquaculture, as a basis for corrective and preventative action.
To develop shrimp culture methods which are not destructive to mangrove forests, and to further develop the culture of other marine and freshwater species in harmony with the environment, e.g. crustaceans, molluscs and finfishes.
To develop a programme of close co-operation with other countries in the region for environmental protection. In countries adjacent to the Eastern and South China Sea, close co-operation will be necessary to preserve the aquatic environment and marine resources.
To establish a project in Vietnam entitled: “The utilisation and management of inland and coastal waters for aquaculture”. The project would study the inter-relationship between aquaculture and the environment and construct models for the utilisation of different aquatic ecosystems (e.g. coral, estuaries) for aquaculture and fisheries development.
To hold a national workshop in Vietnam to prepare a national strategy for the development of aquaculture in relation to the environment. The national strategy may include elements of further research, training and information exchange.
For the investigation of fishery resources: from 1959–1985 there has been a general survey of environment in inland and lowland waters and results have been obtained. There is a preliminary estimation of aquaculture environment, which has identified rich fishery potential in a large ecological areas of Vietnam, mainly in the Red river delta, central part of the country and Mekong river plain. The organisation of research is sometimes not synchronised so the information and scientific data obtained are not as useful as they could be. In order to have a reliable scientific base for the development of aquaculture in different ecological regions, as well as the assessment of fishery potential in the ecological regions, it is suggested that:
The surveyed areas of littoral ecological fauna should be widened from north to south, studying the main relations in the ecological system and relative effects of different environmental fluctuations. On the basis of such a study procedures for sustainable development of the biological resource can be developed;
A study to construct a scientific basis for the fishery resource division and develop standards on the environment which are directly relevant to aquaculture. The study of natural food, fish and shrimp and other aquaculture and fishing resources having commercial significance is required to understand their ecology and improve management of resources.
To carry out the above tasks, we would kindly request organisations in the Indo-Pacific region (NACA, UNDP, FAO, etc) region to assist in financing and establishing a project to study systematically and to assist in the development of aquaculture in Vietnam over the coming years.
Ba, N. G. and Chanh, C. M. 1988. Study on water quality in the Lower Mekong basin according to microbiological standards. Workshop on surface water quality in the Lower Mekong Basin, Ho Chi Minh City, Vietnam, 7–13 September, 1988.
Hong, P. N. and San, H. T. 1993. Mangroves of Vietnam. IUCN, Switzerland.
Hong, P.N. 1983. Some research results on the structure, distribution and succession of mangroves in coastal ecosystems of Vietnam. In: The conference on rational use of natural resources and Environmental Protection, Hanoi, Nov. 1983: 85–111 (in Vietnamese).
Luu, T. T. 1991. Aquaculture and fisheries in the Lower Mekong Delta. Mekong Delta Master Plan, Working report on Fisheries, VIE/87/031. Ho Chi Minh City. 24pp.
NEDECO, 1991. Mekong Delta Master Plan. Environmental aspects. Working Paper Number 9. SPC/World Bank/Mekong Committee/UNDP. Ho Chi Minh City, June 1991.
Xuan, V. T., Nguyen, V. S., Ni, D. V., Ut, N. T. and Hoang, H. M. 1984. The rice-shrimp cropping system on potential and actual acid sulphate soils in the Mekong Delta. Background report for the Mekong Delta Masterplan.
ANNEX I: LEGISLATION AND POLICIES CONCERNING MANGROVE ECOSYSTEMS1
The adverse effects of further exploitation on the remaining mangrove areas after the second Indochina war has lead the Ministry of Forestry (MOF), as the principal government agency mandated, to implement policies relating to these resources. The MOF has initiated necessary forest restoration and preservation measures. The necessity and urgency of proper management became evident in the 1980's when mangrove forests had degraded considerably due to human activities.
A directive on the technical procedure for the establishment and maintenance of mangrove forests was issued on 24 October, 1984, with Decision No. 975 QPN 7–84. In addition, in order to achieve these environmental objectives, resolution No 246/HDBT of the Council of Ministers on September 20, 1985 regarding the rational use of natural resources and environmental protection, was enacted.
Article No. 5 of the “Law on Forest Protection” was promulgated on September 5, 1972 and makes a provision for the establishment of protected areas. Within forest preserves it is now prohibited to fell trees or to kill birds and other wildlife. However, deforestation has increased year after year and as a result there are rapid increases in the damage caused by natural calamities. Hence the Prime Minister enacted instruction No. 53/CT on 24 February, 1990 for the establishment of plantations for the protection of the environment, including coastal and estuarine habitats. Based on this, the MOF promulgated decision No. 413/QD on 18 September, 1992 initiating a plantation programme for 6000 ha of suitable area along Minh Hai's coast.
In April 1987, the Government promulgated a policy for the sustainable use of wetland areas throughout the country and declared 8 protected areas in wetland regions, covering a total of 23,701 ha, including 6 mangrove areas, covering 20,671 ha. The mangrove areas declared as protected are Tram Chim (9,000 ha), Bac Lieu (40 ha), Cai Nuoc (20 ha), Dam Doi (119 ha), Dat Mui (7,547 ha) and Vo Doi (3,945 ha). Of these, Tram Chim is located in Dong Thap Muoi province, Dat Mui and Vo Doi in Ca Mau cape and Bac Lien, Cai Nuoc and Dam Doc, designated as bird sanctuaries are located in Minh hai province. The Minh Hai authority recently made a decision to preserve Con Trong and Con Ngoai, the newly formed islands in the estuary of the Ong Trang river.
The mangrove forests adjoining the river systems and along the coast are important green belts and serve to protect human life, property and fields against coastal and riverbank erosion, strong monsoons and storm floods. The government has therefore declared strict regulations to protect these forests. Apart from this, establishment of new plantations are encouraged and supported.
The Government of Vietnam also became a contracting party to the RAMSAR convention on January 20, 1989 and designated the mangrove islands of Xuan Thuy district in Ha Nam province for inclusion in the RAMSAR list (Duc, 1990).
The responsibility for coastal development and environmental protection in Vietnam is delegated to the local administration. The provincial People's Committee of Minh Hai (MHPPC) province has formulated a number of decisions, regulations and instructions to protect and limit the irrational utilisation of mangroves. Instruction 19/CTUB, issued on April, 23, 1984 institutionalised the governmental decision No. 184/HDBT on land and forest allocation issued by the Prime Minister.
In situations where mangroves have been destroyed for shrimp rearing, the MHPPC's decision No. 57/QDUB of March 6th, 1989 provided for the demarcation of suitable areas which can be used for shrimp raising. These areas are to be planted up again after 3 to 5 years. Under these regulations, shrimp raising in newly planted or protection forests is prohibited. In addition, the land must be returned to the Forestry Service for reforestation when deemed necessary.
1 Extracted from Hong, P.N. and San, H.T. (1993). Mangroves of Vietnam. IUCN, Switzerland.
Nevertheless, shrimp raising for export has been very profitable and the conversion of mangrove forests to shrimp ponds continued to increase rapidly. The MHPPC attempted to strengthen forest protection by issuing instruction No. 21/CTUB on March 10, 1986 and allowing the Provincial People's Organ of control and People's Court through instruction 359/UBA on September 10, 1986, to punish anyone who destroys forest for the purpose of cultivating shrimps.
Parallel with forest destruction, the over exploitation of mangrove vegetation for timber and charcoal has also been a serious problem. Consequently, the MHPPC has decided to restrict entry into mangrove areas temporarily and increase forest staff for protection. However, the prohibition of exploitation cannot be implemented due to economic difficulties in general and the expenditure for implementation as well as people's great need of timber, firewood and charcoal in particular.
To limit irrational harvest of natural resources, the MHPPC promulgated instruction 33/CTUB on June 4, 1987 regulating natural resource exploitation. Areas were demarcated and classified as forestry, forestry-fishery, fishery and shifting cultivation land.
This decision, however, has had very little effect due to the pressure of continuing spontaneous transmigration into these areas. Following this, instruction 36/UB on November 7, 1988 on the rearrangement of production combined with land and forest allocation was passed and on May 2, 1989 the MHPPC enacted another decision (No. 143/QDUB) regarding the management of mangrove production and restoration.
In March 28, 1991, Minh Hai provincial authorities issued decision No. 64-QD/UB on the policy and measures of management, protection and utilisation of land, forest and water resources including the mangrove ecosystem. Some major features of this included regulation of area for shrimp farming and putting the unused accreted flats on the coast under the control and management of the State and prohibiting all occupation and utilisation of any form in order to protect the environment and formulate measures to manage seashore erosion.
Can Gio district used to be called “Rung Sat” and prior to 1978 was a part of Bien hoa province. In 1978, this mangrove area was transferred to Ho Chi Minh city as a suburban district. Since that time, an extensive plantation programme has been carried out in the area. After some replanting had been completed, the Government passed a number of decisions aimed at enhancing conservation and afforestation efforts in the area.
In response to the increased clearing of forests for shrimp cultivation, Ho Chi Minh city's Agriculture Service issued announcement No. 109/LN-TB on February 17, 1992 prohibiting forest clearance for the purpose of shrimp pond construction. This announcement also required registration of all units and households building shrimp ponds in the mangroves and approval from the Agriculture Service for ponds greater than 1 ha.
On March 17, 1992, Ho Chi Minh City's Agriculture Service issued a temporary regulation (no. 178/LN-QD) regarding the care and preservation of protective forests. The specific points of this regulation are as follows:
Every unit or household which has been allocated land and protective forests for plantation, care and preservation must formulate a management plan under the supervision of the Forestry branch.
Local people will have to assist in the management and protection of forests as well as help in the propagation of the forest and education of people regarding the role of mangroves and the forest protection laws.
The expenditure for the preservation of protective forest will be borne by the Government. Rewards and punishments are used as incentives and disincentives for proper implementation of the regulation.
At some places in Can Gio, thinning has been carried out mainly for income generating purposes and does not follow proper technical procedures. The Ministry of Forestry has therefore issued an official letter no. 1411/VP on 27 July, 1992 concerning forest management in Ho Chi Minh City. Ho Chi Minh City's Agriculture Service has also prohibited the thinning of protective forests in Can Gio as well as trade in Rhizophora apiculata for wood processing. Aside from placing a temporary ban on thinning, since November 1, 1992 this announcement has restricted entry into all protective forests in the area in order to conduct a survey of resources within the forest.
ANNEX II: LIST OF RELEVANT RULES AND REGULATIONS
Regulations of Vietnam Concerning Environment and Aquaculture
Instructions on prohibition of explosion to fish in rivers, lakes and sea (April 1982).
Instructions on some urgent matters of fishery resource preservation (May 1982 and May 1984).
Decision of the Minister of the Ministry of Fisheries on the issuance of regulations of lobster resource preservation (October 1984).
Ordinance of fishery resource development and preservation (April 1989).
Decision of the Minister of the Ministry of Fisheries on the issuance of regulations and management of fishery culture seed.
Decision of the Minister of the Ministry of Fisheries on the issuance of fishery resource preservation organisation.
Law of environment preservation of Vietnam has been set up but it is not yet issued.
Table A1. Water quality standards for drinking water, surface water and fish culture.
|Parameter||Drinking water||Surface water||Fish culture|
|Dissolved oxygen (mg/l)||> 4.0|
|BOD (mg/l)||< 4.0|
|Suspended solids (mg/l)||< 1000|
|NH3 (mg/l)||< 1.0|
|Iron (mg/l)||< 1.0|
|Phenol (mg/l)||< 0.02|
|Feacal coliforms (MPN/100ml)||< 1000|
|Feacal Streptococcus (MPN/100ml)||< 50|