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Melba B. Reantaso1, Bounthong Sengvilaykham2,
Angus Cameron3 and Pornlerd Chanratchakool4

1Network of Aquaculture Centres in Asia-Pacific
PO Box 1040, Kasetsart Post Office
Bangkok 10903, Thailand

2Department of Livestock and Fisheries
Savannakhet, Lao PDR

3AusVet Animal Health Services
140 Falls Road, Wentworth Falls
NSW, Australia

4Aquatic Animal Health Research Institute
Department of Fisheries
Kasetsart University Campus
Jatujak, Bangkok 10900, Thailand

Reantaso, M.B., B. Sengvilaykham, A. Cameron and P. Chanratchakool. 2002. A survey of the socio-economic impact of aquatic animal disease on small-scale aquaculture production and reservoir/capture fisheries in southern Lao PDR. p. 235-252. In: J.R. Arthur, M.J. Phillips, R.P. Subasinghe, M.B. Reantaso and I.H. MacRae. (eds.) Primary Aquatic Animal Health Care in Rural, Small-scale, Aquaculture Development. FAO Fish. Tech. Pap. No. 406.


An aquatic animal health assessment was conducted in August 1999 as part of a framework to develop an aquatic animal health programme in southern Lao PDR. The objectives of the survey were to use a participatory farm/household/community survey to assess the socio-economic impact of aquatic animal disease and production-related problems on six different small-scale aquaculture practices (i.e., fish pond, rice-fish culture, nursery, community pond, state and private hatchery, and capture fishing in reservoirs and natural waters) in southern Lao and to train livestock and fisheries officers from four provinces in aquatic animal health assessment.

A disease exhibiting signs consistent with epizootic ulcerative syndrome (EUS) was recognised by most farmers in most production systems. The other problems recognised were red discoloured patches; deaths with no clinical signs; parasitism by Lernaea; and problems related to technical capability, resource availability, the environment and predation. Losses due to disease and other problems were estimated to range from a low of 5% in a nursery system to a high of 79.4% in a state hatchery. Losses incurred by fishers practising capture fishing in natural waters and reservoirs were 49% and 74%, respectively. EUS-like lesions were reported by a large number of respondents from fish ponds and capture fisheries, as well as from two community ponds. The greatest losses occurred in state hatcheries (US$6,458/yr) followed by reservoirs (average of US$1,028/family/yr), which partly reflects their higher potential production relative to the other systems. Among the various production systems surveyed, losses in state and private hatcheries appear to have the most significant impact, as any drop in production results in a decreased capacity to meet the demand for fry and broodstock for fish ponds, nurseries, hatcheries, and rice-fish ponds, as well as availability of fry for stocking in reservoirs and natural waters. Little social impact was reported for most production systems; however, disease in fish production facilities often meant that more time had to be spent catching fish, greater competition in capture fisheries, and more time spent obtaining and preparing alternative food sources.

An institutional and training needs assessment carried out in conjunction with the survey found that district staff play a central role in aquatic and terrestrial animal health, and that their dual responsibilities should be taken into account when training is planned. Increased efficiencies can be achieved by integrating the activities of the veterinary and fisheries divisions in the areas of surveillance, information systems and diagnostic laboratories. District staff should be seen as generalists, and receive training that will help them in the range of their duties, while having access to a network of provincial and national specialists in different fields. The results and recommendations of this survey, including the institutional and training needs assessment conducted independently by a consultant (Dr. A.Cameron), will form the basis for the formulation of a strategy for aquatic animal health management in southern Lao.


A Network of Aquaculture Centres in Asia-Pacific (NACA)/South East Asia Aquatic Disease Control Project (SEAADCP)/Aquatic Animal Health Research Institute (AAHRI) mission to southern Lao in June 1999 discussed possible co-operation with the Regional Development Committee (RDC) on aquatic animal health management in southern Lao, including a survey of fish health in small-scale aquaculture systems and the development of local capacity for aquatic animal health management. This was followed by a three-day appraisal and preliminary survey of hatcheries and fishpond facilities in Savannakhet and Khammouanne provinces in mid-July to assist in identifying specific issues and planning of the survey.



The objectives of the survey were to (i) assess the social and economic impacts of aquatic animal diseases on small-scale aquaculture practices in southern Lao; (ii) identify aquatic animal health training needs for the two provinces; and (iii) identify institutional requirements for aquatic animal health.

Survey Methods

The survey was conducted between 2-13 August 1999 by a team of national livestock and fisheries officers from Savannakhet, Khammouanne, Champassack and Vientiane provinces and international participants from SEAADCP, AAHRI, NACA and AusVet. Prior to the survey, a workshop held on 2-3 August (a) provided orientation for participants on the objectives and scope of the survey, (b) defined the team composition and job roles, (c) determined the areas and production systems to be covered, (d) developed the guidelines and approach and (e) discussed methods for analysing and reporting the results of the survey.

The 15 surveyors were divided into four groups, and the survey was conducted through farm/village visits, key informant interviews and group discussions. A set of questions and key points were identified, discussed and developed, and these ultimately served as prompts to guide the field surveyors. The aim was to obtain qualitative and, where possible, quantitative information on farmers' perceptions, attitudes, opinions and experiences with regard to aquatic animal health and other production-related issues affecting small-scale fish production and capture fisheries in southern Lao. The survey focused on key information that was likely to be available within the production systems being examined. The section below lists the main questions and key points that were addressed in this survey.

What problems exist? (List and rank health and production problems related to aquatic animal production). Key points:



Describe the problem

What is the effect of these problems? Key points:

Economic impact (quantify)

Social impacts

What do you do about these problems? Key points:

Survey Area

The survey focused on two provinces in southern Lao, Savannakhet and Khammouane, covering four districts, namely: Champhone, Outoumphone and Pinh districts in the Province of Savannakhet, and Thakhek District in Khammouane Province (Fig. 1).

Survey Sample

The target group for the survey was small-scale fish farmers and rural fishermen involved in the following production systems:

The local staff made estimates of the total number of families or enterprises in the target areas that fall into each of the above categories. A number of villages and enterprises were then selected to ensure that each of the production systems was represented in the sample, as shown in Table 1. The sample was, therefore, a non-random, purposive sample.

Table 1. Production systems covered in the survey, with estimates of the total number of families/enterprises in the target areas.

Data were collected by a combination of small-group and key-informant interviews using a semi-structured approach. The three main questions were asked in turn, and after each main question, a discussion took place to explore, refine and characterise the information being sought. All analysis and reporting was done in the Lao and English languages in parallel.


General Description of Farming Systems

Fish pond production

The size of fish ponds included in this survey ranged from 500 to 10,000 m2, with water depth of around 80 cm to 2.5-3.0 m. The ponds are mainly rainfed. The culture period starts from April-May, and the harvest season begins in September-October; however, farmers usually begin to take fish for consumption three months after stocking and progressively thereafter until the end of the dry season. The cycle starts again at the beginning of the rainy season.

Stocking density depends largely on availability of fry in the area, and may range between <1-5/m2. The system involves minimal inputs, with little use of liming. Production, therefore, depends largely on the natural productivity of the ponds. Selling of fish directly to the market is not common. The usual practice is for customers who want fish to come directly to the farm. The farmer either sells the fish or organises the catching and/or preparation of food, depending on the requirements of the customer. Fish are also exchanged for labour during rice harvest, or for other agricultural products, such as vegetables. Aside from providing food for the family and an additional source of income, fish are used during weddings, funerals, festivals and other community celebrations.

Most of the farmers interviewed were involved in pond aquaculture as a secondary source of income, the main source of income being agriculture. However, there are indications that more farmers, particularly those who already have ponds, are intending to take up aquaculture on a full-time basis, as they perceive it to be more profitable, less laborious and requiring minimal inputs. There are a good number of potential fish farmers who are constrained by a lack of land, or in some cases, by a lack of funds, for pond construction.

Rice-fish production

The average area used for rice-fish production is about 0.3 ha. The average stocking density using tilapia, common carp and Java barb (3-5 cm length) is about 2,465, or approximately one fish per m2. There is only one production cycle per year, with a duration of eight months, starting at the beginning of June, about one week after rice planting. The pond is fed with rice bran at the rate of 3-5% of fish body weight, and manure (cattle dung) at the rate of 0.5-1.0 kg/m2/yr. Normal production is about 112 kg, equivalent to 372 kg/ha. Some fish are consumed, and the rest (market size of four fish per kilogram) are sold to the market at the current price of 10,000 Kip/kg (1 US$= 9,600 Kip).

State hatchery production

One state hatchery in Khammouane Province was included in this survey. The hatchery relies on water fed by gravity into square concrete tanks, usually from a stream or reservoir. The water supply is largely insufficient.

The species of broodstock most commonly used for fry production are common carp, silver carp and bighead carp, mrigal, rohu, Java barb, catfish and tilapia.

The state hatchery employs induced spawning techniques using lutenising hormone/releasing hormone (LHRH) analogue in combination with domperidone maleate. Chemical hormones, now widely available from Thailand ("suprefact," "motilium"), Vietnam and China, are now commonly used instead of fish pituitaries to induce spawning.

Total fry production from the beginning of 1999 to the time of the survey was 785,000 fry, an increase of about 50% from the 1998 production of 400,000. Current demand for fry in Khammouane Province stands at two to three million fry.

The state hatchery conducted a training programme for farmers in 1996 through which 14 families were trained in nursery techniques using hapa nets. In 1997, 70 families were trained in pond-culture techniques. If funds were available, the station could produce more seed to meet local demand, and they could train more farmers.

Private hatchery production

Private hatcheries are also in operation, and six were visited during this survey. Farmers are using fewer species (e.g., common carp, tilapia, Java barb and mrigal) compared to state hatcheries; they also use hormone induction techniques.

Nursery production

Nursery production was pioneered by the Asian Institute of Technology (AIT) Outreach Project in Savannakhet Province. This involves taking fry from state hatcheries and nursing them for one month before sale.

Community pond production

Community ponds are organised by the people of the village according to a government policy of empowering local communities through developing livelihood projects that support social services (e.g., schools, latrines, community halls, health services, support for festivals, material contribution to weddings and funerals) that are beneficial to the whole village.

In Champhone District, with a population of 97,647, there are five community ponds located in Nong Hung, Dong Deng, Bann Pai Khong, Bann Buk Tong and Bann Ouie Say. These ponds range in size from 2 ha water area in Bann Buk Tong and Bann Ouie Say, involving 50-60 families, to 10 ha in Nong Hung, involving more than 100 families. In Khammouanne Province, there are three community ponds, one each in Thakhek, Seabang Fai and Hinboun districts, with a total of approximately 182 families involved. The description of the management and operation of community ponds given below is based on information collected in Nong Hung village in Champhone.

The community pond is managed by a village committee of three persons: the head of the village, an elder and a security person. The whole management is supported by six committees: (a) administration, (b) a controller or financial manager responsible for daily financial transactions, (c) a fishermen's group involved in the technical operation, (d) an accountant, (e) a treasurer and (f) a cashier. Apart from these committees, several groups involving women, the elderly, junior citizens and security people are involved in specific tasks in the management of the community pond.

Community fishpond production is a secondary income and food source for the village, the main activity being rice and vegetable production. Every family participating in the operation of the pond gets an equal share of fish, and a certain percentage of profit earned is used for community projects.

In Nong Hung village, a community pond was started in 1998 and now involves 117 families. The money earned from fish production is being used to support a school in the village and to repair the water outlet. Ten kilograms of fish are provided to the community during a festival, and 5 kg for every wedding and funeral in a family.

Fish production from the community-managed pond has raised the general standard of living of the villagers and was regarded as more profitable and less laborious as compared to agriculture and livestock production. Aside from the additional income generated and the contribution to food availability for the family, it was regarded as generally good for society.

Reservoir fisheries

Man-made reservoirs, mainly for hydroelectric power or irrigation, are also used for fish production in southern Lao. In Champhone District alone, there are four reservoirs: Soui Reservoir, Nhot Houi Bac, Thong Bac and Oui Chiao.

The Soui Reservoir in Bann Don Ngeng, for instance, started as a small stream. In 1985, the Department of Irrigation constructed a reservoir for agricultural purposes. In 1992, the DLF in Savannakhet stocked several fish species, such as common, silver and bighead carps, rohu, mrigal and tilapia. The reservoir now stretches to about 5,046 ha of water area with more than 30 villages and four sub-districts surrounding it. About 100 families are catching fish daily from this reservoir.

Aside from stocked species, snakehead, catfish, gourami and "corica" are among the wild species present in the reservoir. "Corica," the mature size of which is about 4-5 cm, are collected and sold in both fresh and fermented form. Women are primarily involved in collection, and the maximum catch is about 10 kg/day, valued at 5,000 Kip/kg (1 US$=9,600 Kip). The peak season for collection is between November and December.

Capture fisheries

Capture fishing involves catching fish in streams, lakes and other water bodies. In Thakhek District, for instance, a 150 m2 dam was built near the Nong Tour Stream. The stream that feeds the dam has a water area of 200,000 m2. There are some seven villages surrounding the stream and dam area. Many species of wild fish are caught, and about 200 fishermen are fishing daily as a secondary activity, as in reservoir fishing. The normal per capita daily catch is about 5 kg, of which, 1 kg is consumed and 4 kg are sold.

1"Corica" is a transliteration of a local common name. The scientific name of this species was unknown at the time of publication.

Aquatic Animal Health and Production-Related Constraints Affecting Small-scale Aquaculture and Fisheries Production

In a previous survey (LAO/97/007) conducted by FAO which covered five provinces including Savannakhet, several causes of fish mortality were identified (see Box 1). The survey reported that farmers frequently mentioned mortality, and ulceration and wild fish mortality, particularly in snakehead and catfish, consistent with EUS, which occurs annually during the transition between the cool and hot seasons. Mortalities of cultured major carps and Java barb in fish ponds in 1998 were reported in Sayaboury and Oudomxay provinces, northern Lao. The survey concluded that the impact of fish disease on aquaculture and fisheries in rural populations is presently unquantified.

About 20 different disease and production-related problems were identified during the current survey. They are ranked below (Table 2) according to the number of farmers, families or enterprises who reported each problem.

The different fish disease and production-related problems listed in Table 2 are similar to some of the problems identified by the Lao/97/007survey. These problems can be classified into several broad categories, namely:

Box 1. Reported fish mortality from survey of LAO/97/007 target provinces.1

Cause of mortality (number of respondents)
Unspecified mortality (40)
Unspecified disease (29)
Ulcerated bodies (14)
Red spots (5)
Spots (4)
Red scales (1)
Predation (2)
Mortality at stocking (2)
Water too hot (2)
Low oxygen (3)
Insufficient water (2)

No disease reported (296)

Total repondents (373)

1Source: LAO/97/007 unpubl. data.

Disease with clinical manifestations, susceptible species and time of occurrence similar to that described for EUS

Disease with clinical signs similar to EUS (erosion/ulceration around the mouth, tail region and body surface) and occurring between November and March was found in fish ponds, community ponds and reservoir/capture fisheries, mostly affecting wild species like snakehead, catfish and eel. One farmer reported these signs in silver carp. The only species confirmed to be susceptible to EUS in Lao PDR is snakehead (Lilley et al. 1998), but the results of the survey based on farmer interview seem to indicate that other species are also affected by this disease. The first reported occurrences of EUS in fish ponds and community-pond systems were in November-December 1997 in Savannakhet Province and in 1994-1995 in Khammouane Province. Farmers reported that this disease occurred among wild populations in reservoirs and natural water bodies as early as 1978-79 in Khammouane Province, and that it was first observed in 1991-92 in Savannakhet Province. Farmers report continuing losses up to the present.

Parasitism by Lernaea

Infections by the parasitic copepod Lernaea were reported in fish ponds, rice-fish culture and state hatcheries. Mortalities are common when infections are heavy or when small fish are involved. Lernaea may predispose fish to other infections such as EUS, and render them unmarketable due to associated lesions.

Unspecified disease

An unspecified disease characterised by red patches with intact skin affected mainly Java barb and occasionally native barb, silver carp and snakehead. These clinical signs could be the result of physical handling, or could be caused by any one of a number of diseases, including EUS. The signs are reported to occur year round and are seen in both live and dead fish.

Mortalities showing no apparent signs

Mortalities of cultured Java barb, common carp, bighead carp and mrigal, and of wild catfish, snakehead and eel were reported during the dry season in fish ponds, reservoirs and natural waters. They may be associated with poor water quality due to the low water level during these periods.

Predation and theft

Predation by snakes, fish and crabs was a major problem reported in fish ponds and rice-fish ponds. The state hatchery also reported predation by insects. Fish-pond operators reported problems related to theft.

Problems associated with resource availability

Problems related to the availability of necessary resources were reported in varying degrees by fish-pond and state and private hatchery operators. They included inadequate supply of fry, lack of food, lack of water, difficulty in water management, not enough nursery ponds, not enough hapa nets and lack of oxygen cylinders.

Problems associated with technical capability

These included lack of technical knowledge or experience, use of fry that were too small, and overstocking (reported mainly by fish-pond operators); poor selection of broodstock, low hatching rates and damaged eggs (reported by private hatcheries); and poor genetics (reported by the state hatchery).

Overstocking results from the farmers' desire to purchase as many fry as they can afford and to stock them in their ponds without consideration of the required material and management inputs (feeding, fertilisation etc.) and the resulting technical problems, such as poor water quality and disease. The intention is to stock more in order to get more at harvest, and this situation deprives other farmers of their share of fry available in the market.

Table 2. Ranking disease and production-related problems and number of respondents reporting for each production system.

Natural problems

This category includes flooding of fish ponds, erosion of dikes in the state hatchery, and weed and pollution problems in reservoirs.


Social Impacts

Of the seven production systems covered in this survey, diseases and production-related problems were reported to have no social impact on rice-fish, community-pond, private-hatchery and nursery systems. On the other hand, the social impacts brought about by disease and production-related problems in pond culture, the state hatchery and reservoir/capture fisheries are indicated in Box 2. These include the time required to find other food, as well as the costs involved, an increase in the price of fish and theft from ponds. A state hatchery in Khammouanne Province experiencing disease and other problems is unable to provide the required seed to the farmers, and this has resulted in decreased aquaculture activity and a decrease in general fish consumption. For reservoir and natural fishing, disease resulted in a greater amount of time being spent catching fish, greater competition among fishermen, and theft due to lack of food. In all systems, families were generally concerned about consumption of diseased fish.

Box 2. Social impacts of disease and other production-related problems.

Pond culture

  • need to find other food
  • time taken getting other food
  • cost of other food
  • price of fish increases
  • theft due to lack of food

State hatchery

  • decreased use of aquaculture
  • decreased consumption of fish
  • not enough fish seed to provide to farmers

Reservoir/capture fishery

  • decrease in number of fish
  • longer time to catch fish
  • greater competition for catching fish
  • theft due to lack of food

Economic Impact

To give an indication of the value of production losses caused by diseases and other production-related problems, an estimate of production losses was calculated from data on expected production, actual or realised harvest, and market price at the time the fish were sold, excluding the other inputs to the system. For reservoir and capture fisheries, losses were computed based on daily catch during normal fishing conditions and catches during disease events. This was then converted into an annual (number of fishing days in disease events/yr) and family basis. All figures are presented as average production loss for each production system on a family/yr basis (see Table 3).

Table 3. Estimated production losses (1999 production cycle) due to disease and other production-related problems in small-scale aquaculture and fisheries in southern Lao.

Production losses were estimated from a low of 5.0% in nursery systems to a high of 79.4% experienced by the state hatchery. Losses from hatchery production (both state and private) range between 64.7 and 79.4%, primarily due to factors such as limited technical capability, unavailability of materials and equipment for broodstock management and fry production, and in some cases, parasitism by Lernaea and predation by insects, snakes, crabs or fish. EUS-like lesions were reported by a large percentage of respondents (59 families) and by the two community fish ponds (117 families surveyed). The community pond in Khammouane (87 families), reported EUS-like lesions on fish, but not in significant numbers. Losses incurred by capture fishing in reservoirs and natural waters were estimated at 73.8 and 49.0%, respectively. This is due to several reasons, among which are overfishing without restocking, use of inappropriately sized nets, water pollution and disease. Disease problems include a disease similar in appearance to EUS, red spot and mortalities with no apparent signs. In both fish ponds and rice-fish production systems, where losses were reported to be 25.8 and 55.0%, respectively, the most common problem was predation by snakes, crabs and fish. Other problems were related to lack of technical experience, limited resources, disease (Lernaea infection), flooding and theft. Mortalities without clinical signs also represented a significant part of the production loss.

Among the different production systems surveyed, losses in hatchery systems (both state and private) appear to have the most significant impact, as any drop in production results in a chain reaction in the other production systems; reduced capacity to meet the demand for fry (see Table 4) and broodstock for fish pond, nursery, and rice-fish production systems, and non-availability of fry to stock in reservoirs and natural waters.

Table 4. Estimated fish fry production and demand in three provinces of southern Lao (1996).1

Actions Taken

Actions taken by farmers when confronted by disease and problems related to technical management include generic approaches not specific to any particular problem. In the case of fish-pond operators, use of herbal medicine, liming, draining and drying of ponds, and in some cases, changes in feeding and fertilisation are carried out. For community ponds, villagers try to regulate the fishing gear being used and may resort to changing species. The state hatchery uses several different approaches when dealing with specific problems. These include pre-treating the pond with gasoline in the case of predation, salt treatment and liming in the case of Lernaea infection, and removal of fish affected with white discoloration and sloughed scales. The more general approaches included increasing the number of broodstock, changing hatching equipment, increasing the number of ponds and improving management.

Farmers involved in rice-fish systems and private hatcheries are generally not taking any particular action in relation to specific problems, while those involved in capture fishing remove affected/dead fish and report occurrences to government stations.

The government, on the other hand, tries to provide training and technical support (seed supply, equipment), and advises farmers to stop movement of fish and consumption of affected species.


An analysis was undertaken of all institutions involved in aquatic animal health in southern Lao, including an examination of institutions working in livestock and animal health that may, in the future, be able to co-operate with aquaculture activities.

The main findings of the analysis are:


An analysis of training under various projects over the past few years was undertaken, and the needs of different staff assessed. The conclusions of the analysis are that:


Even though aquaculture and fisheries in southern Lao are still in their infancies, there is a clear indication from this survey that production-related problems and aquatic animal diseases can play a substantial role in determining overall productivity, and that they are affecting potential development. The major issues identified during the survey include:

Diseases and problems

Socio-economic impacts of disease and other problems

Actions taken by farmers

The findings and recommendations of this survey, including the institutional and training needs assessment, will assist in the formulation of a strategy for aquatic animal health management in southern Lao.


This section, based on the final-day workshop, presents the recommendations agreed upon by the participants that are directed at the major issues and problems identified during the survey.

It was recognised that, as a matter of priority, the disease and production-related problems identified during the survey should be addressed in the following order:

1. Problems associated with technical capability
2. Disease with clinical manifestations similar to EUS
3. Problems associated with resource availability
4. Predation problems: snake, fish, crab, insect and human (theft)
5. Deaths/mortalities with no apparent sign
6. Lernaea infection
7. Unspecified disease showing red patches

The following specific activities were identified as necessary to support a programme that will establish systems for improved productivity and enhanced capability of both government staff and farmers to address problems:


The financial and technical support of AusAID/Agriculture Fisheries and Forestry Australia (AFFA) to the FAO/NACA Regional Programme on Aquatic Animal Health, under which this activity has been undertaken, is gratefully acknowledged. The authors would also like especially to thank the RDC organisers and trainers (Duongchith Littdamlong, Nick Innes-Taylor, Bouthonome Chamsin and Bhonthong Sengvilaykam) and the livestock and fisheries officers of Lao PDR (Boontian Somthaboun, Phansy Homkingkeo, Duoangchanch Keovangsak, Bounmy Phiewvankham, Nouphone Vongphachanh, Somsanouk Nivongsa, Thongsiane Phongsavat and Thonsathit Xayxanadasy) and the farmers who participated in the survey.

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