Fish is one of the most popular sources of animal protein in Viet Nam. It is estimated that some 30–35% of protein consumption of Vietnamese people is derived from fish products. Production of fish through aquaculture practices has traditionally played a very important role in providing fish to rural and urban populations. It is estimated that aquaculture production has increased by about 5–7% per year over the past decade. The demand for fish in recent years has grown substantially with increasing incomes. The Government of Viet Nam plans to increase per caput fish consumption from currently 10 – 12 kg to 13 – 15 kg by the end of the century (Ngoc, 1995).
However, it is important to note that about 80% of Viet Nam's population lives in rural areas. Despite increasing average incomes, most rural people still face problems of poverty and limited opportunities to improve their living conditions.
It is generally recognized that there is great potential for aquaculture development in Viet Nam. Opportunities exist for pond and cage based aquaculture production as well as for rice-fish cultivation, and culture-based fisheries in larger water bodies, including reservoirs and lakes. There is also growing interest for development of coastal aquaculture, particularly shrimp culture development.
According to the Master Plan for Aquaculture Development (published in 1996 by the Ministry of Fisheries), Viet Nam has around 1.4 million ha of inland and coastal waters suitable for aquaculture purposes. It is estimated that this total of available water surface includes low-lying rice fields (39.8%), reservoirs (28.7%), perennial tidal fiats (21.1%), lagoons (6.2%), and small lakes (4.2%). Only one third of the available water surface (530.000 ha) is already being used for aquaculture activities. About 61% (325.000 ha) is considered suitable for fish culture while the remaining 38.9 % (205.000 ha) is considered suitable for shrimp production. Of 325.000 ha used for freshwater aquaculture, more than 90% are under pond culture and the rest is used for rice-fish cultivation.
Aquaculture practices in rural areas are being promoted for several reasons. It is expected that fish production through aquaculture and culture-based fisheries will contribute to :
increased household food security and supply of fish in farming comunities; nutritional benefits for individuals in many cases can be substantial,
signicant increase of incomes of farmer households through sale of market size fish or fish seed,
diversification of existing agricultural practices, particularly in highland zones and remote mountainous areas,
reduction of migration of rural people to urban centres, by providing additional sources of income and food,
reduction of environmentally damaging practices of deforestation and poor agricultural practices resulting in soil erosion, by providing alternatives for income generation and food production,
greatly reduced dependence on application of pesticides in rice paddies through improved rice-fish cultivation methods.
Aquaculture practices in northern Viet Nam are very diverse. Freshwater aquaculture is traditionally integrated with crop production, horticulture and livestock husbandry. Chung and co-workers of the Faculty of Agricultural Economics, Hanoi, studied the various types and levels of aquaculture / agriculture integration in different agro-ecolgical zones of northern Viet Nam, including lowland, midland and highland regions and the northern provinces of northern central part of Viet Nam. For the purposes of their study, fish farms were grouped as to belonging into four categories:
VAC farms are those whose farming system consists of all VAC components, whereby V = vuong - gardens (horticulture); A - Ao - ponds (aquaculture) and C = Chuong - animal sheds/pens (livestock husbandry);
Aquaculture/livestock farms include those mainly engaged in aquaculture and livestock husbandry;
Aquaculture/horticulture farms are those mainly practicing horticulture and aquaculture; and
Rice - fish culture farms are those primarily engaged in rice-fish culture.
However, as pointed out by Chung and co-workers, the levels of aquaculture/agriculture integration are very different form region to region and from farm to farm. Moreover, it should be noted that farm households growing fish, while being grouped into one of the three latter categories, in many cases would still be engaged in a range of other agricultural activities (including livestock husbandry, horticulture, and rice production), however to a lower degree. In addition, other freshwater aquaculture methods practiced also include cage culture, cultivation of aquatic plants as animal feeds (water spinach, water hyacinth and water taro), and, in a limited number of cases, rearing of soft shell turtles, frogs and snakehead.
There is a wide diversity of species grown. However, most farmers (95% of farmers surveyed) are practicing polyculture raising grass carp, silver carp, common carp, bighead carp, rohu, mrigal, mud carp, and sometimes tilapia, in varying compositions. Farmers practicing monoculture are utilizing cages in water bodies of the highland and midland zones.
Based on their socio-economic survey, Chung and co-workers conclude that :
The most common and efficient model for aquaculture/agriculture integration is VAC farming, followed by rice-fish culture, then aquaculture/livestock husbandry (primarily pig rearing), and finally aquaculture/horticulture integration;
VAC farming appears to be the best model of aquaculture/agriculture integration, in terms of on-farm input use, productivity and gross margins;
The VAC, aquaculture/livestock and rice-fish integrated farming systems help the farmers in obtaining higher returns, achieving best use of on-farm inputs, lessening their dependence on purchased inputs and sustaining patterns of farm resource use;
Aquaculture plays an important role in these integrated farming systems, in providing farm income, using on-farm inputs, creating employment and reducing risks for the farm household;
These systems play an important role in food supply, job creation and sustainability of rural economy. They also provide opportunities and directions for farmers to diversify the traditional rice-based production patterns into more sustainable farming systems that enable farmers to obtain better quality of life with less environmental damage and health risk.
Results from the socio-economic survey indicate that aquaculture is practiced as a main farming activity by only 28.4% of farmers surveyed, while crop production and livestock rearing are the main occupation of more than 60% of total respondents. In most farm households, aquaculture is regarded as a minor farming activity to supply food for household members. This can be attributed to lack of knowledge and practice in aquaculture, and also to unavailability of ponds or cages.
The socio-economic survey evaluated farmers' perceptions about general problems in VAC farming and specific problems in aquaculture. The problems identified include:
Constraints due to present land use policy and regulations are related to many time-consuming formalities involved in obtaining permission from provincial authorities to utilize land used for rice production for purposes of VAC farming, including aquaculture. Further, ponds are allocated to farmers for too short a period of 4–5 years which seems to discourage farmers from long-term improvements in pond management (maintenance and operation) or pond development (expansion). Access to credits is a problem for many farmers because interest rates are too high and terms of payment too short. Thanh and co-workers (Environment Study) in their assessment of VAC farming systems in Bacninh, Vinphu and Sonla provinces noted that insufficient investment for fish culture purposes does result in low productivity and income.
Natural hazards identified include cool weather in winter and, in particular, flooding. Chung and co-workers suggest that appropriate pond construction, and increasing the height of pond dikes can help minimizing losses due to flooding. However, rehabilitation of ponds and re-construction of pond dikes following floods may result in additional maintenance costs of about 20%, as noted by Thanh and co-workers (Environment Study). In some cases, flooding patterns may have to be considered in aquaculture site selection or pond development. This should apply in particular to developments in new areas or to expansions of existing pond culture areas.
The main fish disease problem reported for all regions studied is red spot disease in grass carp causing large mortalities in both ponds and cages. It is said that this disease spreads in waters of irrigation canals or rivers affecting many aquaculture units over wider areas. RIA No.1, through the Project KN-04-12, has developed a herbal medicine which seems to be quite effective in preventing the occurrence of this disease problem, as recorded by Thanh and co-workers (Environment Study).
Lack of fingerlings is a major problem for farmers, particularly in highland and midland zones. Fingerlings are supplied from different sources (market/middlemen, hatcheries, home production and neighbours). Only about 37% of the famers surveyed obtain their seed from hatcheries. About 44% of the farmers stated that they lack seed of good quality. There is a heavy reliance on seed marketed by middlmen at high price, which are said to be of low quality resulting in high mortality rates. Farmers lack experience in recognizing seed in terms of species and good quality. Small fish remaining from last harvest are sometimes re-stocked into ponds for the next grow-out period.
The Socio-economic Study indicates that only about one third of the farmers were skilled to efficiently manage their VAC system. Overall, about 65% of the fish farmers lacked technical experience in aquaculture. In many cases ponds are not being utilized to grow fish, but for cultivation of aquatic plants being fed primarily to pigs.
Ponds are often stocked at an inappropriate composition/ratio of fish species, with too high stocking densities of common carp, grass carp and silver carp, and too low densities of rohu and tilapia. The inadequate ratio of species stocked causes that food organisms and nutrients available in the pond are not fully utilized. However, stocking densities applied are generally higher than recommended. Further, fingerlings being stocked are generally too small. Overstocking and small stocking size often lead to small marketable size and low farm gate prices. Problems of seed supply often result in sub-optimal stocking times i.e. too early or too late in the year, and not when water temperatures are most suitable for stocking of fingerlings.
About 81% of all farmers utilize on-farm feeds (rice bran, grass, garden leaves, manure, domestic washing, kitchen wastes, night soil) to fertilize their ponds. However, only 20% of farmers applied these inputs in an appropriate way. The low productivities recorded across all farming systems and regions may well be due to inefficient feeding techniques and sub-optimal stocking structure and densities.
Thanh and co-workers (Environment Study) recorded water quality data in ponds and cages. The preliminary results may indicate that sometimes there may be some water quality problems, although the data collected may need further validation. However, some farmers stated that one of their problems is “unchangeable water” (see above). This may indicate that water quality problems occur, or that farmers wish to intensify their production, which would require more frequent or even regular water exchange. It is noted that ponds are often drained only once a year (50% of farmers drain their ponds after final harvest in December – February), or even only every two years. Practices of frequent or regular water exchange are found only in a relatively small number of cases, e.g. in the Sonla Demonstration Farm or the farm at Hum village, both located in the highland zone, where water exchange through gravity is possible. Effluent quality data collected (Environment Study), even though preliminary, would indicate increased phosphorus concentrations, which however are not likely to have significant effects. Likewise, no significant adverse effect would be expected for cage culture practices studied, as indicated by preliminary water quality data recorded outside the cages located in Red River and Hoabinh reservoir sites.
In their study of sewage-fed aquaculture practices in Thanhtri district, Thanh and co-workers (Environment Study) recorded elevated concentrations of copper, cadmium, lead and nickel in rohu, silver carp and tilapia grown in Duongsat Lake. The concentrations of these metals found in fish meat are above the levels considered to be safe by the Ministry of Health and WHO / FAO. These recent data contradict the findings of the First Mission of the reporting officer in June 1995 (see 1995 Mission Report Section 4.3 , page 10, and paragraphs 111–113, page 40). Dr Dalsgaard, in his draft report on “Public Health Aspects of the Reuse of Wastewater in Aquaculture in Vietnam”, states that “it is likely that the accumulation of toxics in fish and aquatic macrophytes raised in sewage-fed ponds in some areas of Thanhtri district may pose an actual health problem when such produce is consumed” (Section 7.2, page 56; Dalsaard, draft report of November 1995).
Even though it is said (Luu, pers. communication) that most ponds in Thanhtri district are being fed with sewage from domestic sources, and not from industrial sources, it appears that the issue of accumulation of toxic substances in fish products must be addressed. In fact, the Master Plan for a Water Drainage System in Hanoi, approved in 1995, contains plans to channel sewage waters of the To Lich River directly to the Nhue River and Red River, which may help reducing exposure of fish culture areas to toxic substances (see also Section 4.9, page 29 in Dalsgaard, 1995).
Thanh and co-workers have studied the effects of pond developments along River Bui, Bacninh province. Expansion of ponds into the river course in some sections of the river has resulted in narrowing its width to 10 meters, while other sections are usually 30–60 meters wide. As a consequence, ponds and other areas belonging to Bui and Laidong communes are frequently being flooded. Rehabilitation of flood-prone ponds is incurring additional costs to fish farmers. In addition, the decline of natural fish resources in River Bui is being attributed to overfishing and expansion of pond areas. Pond expansion into Hong Ngoc River, Haiphong province, has also been noted during the First Mission of the reporting officer (see 1995 Mission Report, page 8, and page 38, paragraph 98). Due consideration should be given to potential consequences and long-term sustainability of such pond developments.
