Better Health Management in the Asia-Pacific
through Systems Management

Michael J. Phillips

Network of Aquaculture Centres in Asia-Pacific
P.O.Box 1040, Kasetsart Post Office
Bangkok, Thailand

Phillips, M.J. 1996. Better health management in the Asia-Pacific through systems management. In Health Management in Asian Aquaculture. Proceedings of the Regional Expert Consultation on Aquaculture Health Management in Asia and the Pacific. R.P. Subasinghe, J.R. Arthur & M. Shariff (eds), p 1–10. FAO Fisheries Technical Paper No. 360, Rome, FAO. 142 p.

Abstract

This paper provides an overview of systems approaches to aquatic health management. It briefly reviews issues relating to aquatic animal health and the environment; environmental risk factors in aquaculture contributing to aquatic animal health problems; advantages of systems approaches to the prevention of aquatic animal diseases; and the implications of systems approaches for research, training and extension.

INTRODUCTION

This paper discusses the potential for better heath management of cultured aquatic animals through aquaculture systems management. In farming systems research, the interactions between the different types of components of the sub-systems must be identified and understood if the system as a whole is to be properly understood and managed (Dcomampo, 1995). In the context of aquatic animal health, the systems management approach implies an understanding of the ways in which the different components of the aquaculture system interact with one another and the management of these components in a way which provides conditions: (a) optimal for the cultured animals (or plants); and (b) least favorable for the occurrence of disease. The approach relies heavily on environmental management but also includes “non-environmental” factors, as noted in the following list of system “components”:

• soil, water quality, climate, pond location and other factors;

• biological components, including the cultured animal (or plant), stress levels, nutrition and feeding practices, genetic factors, the presence or absence of pathogens and occurrence of plankton bloom;

• human components, such as the management experience of the farmer, access to capital and other resources, traditions and socio-cultural aspects;

• legal/institutional components, which influence the allocation of resources and institutional support, as well as laws e.g., quarantine, trade laws, and access to information, training and appropriate expert assistance; and

• economic components, which determine the supply and demand situation for aquaculture products, and influence farm management decisions which have an impact on aquatic animal health e.g., the degree of attempted intensification.

NEED FOR A SYSTEMS APPROACH

The introduction of many factors into the overall aquatic animal health management picture may appear to some to complicate the management situation greatly. However, there are reasons for taking a broader approach which considers the management of the system, rather than individual components:

• aquatic animal disease is the end result of a series of linked events, therefore, treatment of disease goes beyond consideration of the pathogen. The heavy focus on the pathogen in research, diagnosis and extension can lead to inappropriate and ineffective “cures” which may temporarily remove the symptom, but not the cause (e.g., such an approach can lead to reliance on inappropriate chemicals and other “quick fix” solutions);

• current approaches have so far had limited success in the prevention or cure of aquatic disease. Considerable difficulties remain in dealing with some existing problems, such as the recent economically serious diseases which have emerged in the shrimp industry; and

• large-scale outbreaks of aquatic animal disease, particularly in shrimp, demonstrate the importance of the linkage with other farms i.e., the problems easily spread beyond the management of individual farms, requiring broader ecosystem management approaches to control farm level environmental deterioration and to take preventative measures to avoid introduction of pathogens.

AQUATIC ANIMAL HEALTH, STRESS AND THE ENVIRONMENT

• The environment in which an animal (or plant) is cultured plays a critical role in the degree to which that animal is susceptible to pathogens and the occurrence of clinical disease (AAHRI, 1994; Flegel and Sriurairatana, 1993). and an understanding of the relationship between host, pathogen and environment is important for understanding the cause, prevention and treatment of most aquatic animal diseases. In general, diseases affecting aquatic animals may be grouped into:

• disease resulting from poor environmental conditions leading to direct effects (e.g., low dissolved oxygen, toxins and red tides);

• disease resulting from stress leading to infection by opportunistic pathogens (e.g., vibriosis - an economically important disease of shrimp);

• pathogens causing disease only when animals are stressed (e.g., MBV in shrimp); and

• primary pathogens causing disease without environmental stress. These are comparatively rate, although some recently reported shrimp viral infections such as yellow head baculovirus may fall into this category (even then, environmental management may be required to control entry of such pathogens to the culture system).

The relationships between the environment and the occurrence of aquatic animal diseases are poorly understood, particularly the relations between stress and disease occurrence. For example, it is recognized that shrimp are “stressed” by poor environmental conditions, but the interaction between disease occurrence and stress in shrimp is unclear (AAHRI, 1995). However, enough is known of the general conditions under which healthy aquatic animals exist that the lack of research data is not a major constraint to improved health management using the systems approach. For example, water quality, pond bottom conditions, feed and plankton bloom management are widely recognized as critical for disease prevention in shrimp culture, particularly for commonly occurring opportunistic pathogens (Flegel and Sriurairatana, 1993).

ENVIRONMENTAL IMPACTS AND RISKS

An important and growing concern (e.g., see FAO/NACA, 1995) is the deteriorating environmental condition of some aquaculture environments, placing an additional stress on cultured organisms. The environmental impacts affecting aquaculture systems include:

• those inherent in the site (e.g., water and soils);

• environmental impacts on aquaculture i.e., those caused by non-aquaculturists, such as through industrial, domestic and agricultural pollution;

• environmental impacts of aquaculture i.e., through discharge of pond effluent and habitat changes caused by pond construction; and

• impacts of aquaculture on aquaculture i.e., through self-pollution of water supplies through discharge of pond effluent.

An important concern is the impact of aquaculture on the environment which has been linked to outbreaks of serious disease (see the comprehensive reviews in FAO/NACA, 1995). For instance, self-pollution caused by effluent from shrimp ponds is thought to have contributed to serious disease outbreaks in Thailand, China and India, and it is probably no coincidence that the first serious outbreak of shrimp disease in India was centered on shrimp farms around Kandleru Creek, a poorly flushed tidal creek suffering from self-pollution caused by overcrowding of ponds (India country report in FAO/NACA, 1995). In many cases, however (such as the upper Gulf of Thailand), the impacts of aquaculture effluent are difficult to separate from environmental deterioration caused by non-aquaculture sources. Such problems further highlight the point that aquaculture farms (and their management) cannot be considered in isolation from the surrounding environment.

Existing experiences with such environmental problems and disease outbreaks allow certain conditions to be identified when aquaculture farms have increased risks of environmental problems giving rise to disease. The following need to be considered in assessing environmental risk:

1. Aquaculture system and management

The type of culture system and its management is obviously important, and the following factors affect risk:

Intensification of farming, through increased stocking densities and feed inputs, leading to:

• increased risk of water and soil quality deterioration; and

• increased need for on-farm environmental management (and management expertise).

Open versus closed systems:

• open systems such as cage farms and flow-through pond/raceways systems are exposed to greater risk of external environmental impacts; and

• closed systems offer greater opportunities for environmental control and management.

Aquaculture system diversity:

• monoculture systems have reduced diversity and stability, increasing the likelihood of water quality and soil problems;

Degree of reliance on external inputs (e.g., feed and seed):

• increased reliance on external inputs is related to intensification, and alsoincreased risk of importing pathogens onto aquaculture farms;
  Farm management expertise (e.g., new entrants to the industry with limited experience are likely to suffer greater problems than experienced farms, as is particularly noticeable in shrimp farming).

2. Intensification of natural resource use

The intensity with which aquaculture uses resources, and how aquaculture competes with others for those resources, is important with:

• increasing resource use pressure leading to impacts on aquaculture from increased number of competing users (e.g., agricultural, industrial and domestic users), leading to increased risk of pollution problems. The intense development activities in many areas of Asia, and particularly in coastal areas, are and will continue to lead to environmental deterioration impacting on aquaculture;

• increasingly severe impacts of aquaculture when the resources utilized for aquaculture exceed the capacity of the environment to supply these resources e.g., when self-pollution occurs due to excessive development of cage farms or shrimp ponds in areas with limited water flushing capacity.

3. International Trade

An over-riding influence, and beyond the control or management of individual farmers, is that related to international trade and the liberalization of trading policies within and between countries and regions. Such issues are important in terms of:

• Transboundary movement of aquatic animals:

  The increasing movement of live aquatic animals (and plants) for aquaculture and the aquarium trade increases the risks of the rapid spread of pathogens and introductions of exotic species. Interestingly, such risks are increasing at a time of increased concern to maintain biological diversity and heightened awareness of the risks of uncontrolled movement of aquatic animals; and

• Exchange of technology:

  Rapid spread and introduction of technologies without consideration of environmental impacts increase the risk of environmental problems.

SYSTEMS APPROACHES

The emphasis of a systems approach should be on prevention rather than cure, which is likely to be the most cost-effective, involving both on-farm management and the management of the broader environment, and involving both aquaculturists and governments. Whilst individual aquaculturists are responsible for farm management, the government inputs are essential for regulation of the resource use, particularly land and water, and for helping to provide legal and institutional arrangements which minimize resource use conflicts and environmental impacts (of and on aquaculture).

On-farm environmental management options include:

• Location/site selection concerns

• Operational concerns:

  • water management, including plankton bloom management;

  • soil/sediments;

  • feed (quality and quantity);

  • seed (disease free/stocking density);

  • chemical use; and

  • monitoring and record keeping.

The emphasis on farm management approaches is on: (a) maintaining a suitable environment for the cultured animal; and (b) reducing risks from introduction of infectious agents.

Off-farm management essentially involves the management of ecosystems which support aquaculture, and considerations of environmental impacts, including:

• Reduction or management of environmental impacts within the ecological limits:

  • effluent management and control;

  • controlling risks associated with introduction of pathogens/exotics species.

  Control of environmental impacts on aquaculture:

  • pollution control strategies;

  • reducing user conflicts through fair and equitable allocation of resources; and

  • integration of aquaculture into broader watershed/coastal management strategies.

ADVANTAGES OF SYSTEMS APPROACH FOR ON-FARM AQUATIC HEALTH MANAGEMENT

There are many advantages in further promoting a systems approach towards prevention and cure of aquatic animal diseases, including:

• a more effective solving of aquatic animal disease problems, because the systems approach considers management of the factors leading to disease (the “cause” rather than the “symptom”);

• systems approaches can promote farmer understanding of aquaculture systems and the environment, increasing the capacity to solve future problems, and reducing the reliance on “quick fixes”;

• systems approaches can lead to increased self-reliance by farmers and less reliance on external support from e.g., scientists, veterinarians, and extension officers. Given the lack of sufficient manpower resources, an important consideration for aquatic animal health practitioners should be to reduce, not increase, reliance of farmers on “professional” inputs for disease control and farm management;

• solutions developed through a systems approach are more likely to be workable and appropriate, and contribute more to sustainable development;

• systems approaches can be more cost-effective, as they do not rely on costly inputs (such as chemicals) and can lead to lasting improvements.

IMPLICATIONS FOR TRAINING AND EXTENSION

The adoption of a systems approach raises some important issues also for training and extension of information to farmers:

• training of aquatic animal health practitioners could give stronger emphasis to the systems management approach to diagnosis and control of disease; and

• systems approaches can be used to better define appropriate information requirements and the most effective channels for providing information to farmers.

The adoption of a systems (or more “holistic”) approach in aquatic animal health training, based largely on managing the environment in a way which ensures it is suitable for the animal and not for the pathogen, is increasingly being recognized as an important way forward in disease control (see also the excellent manual by AAHRI - which exemplifies this approach - AAHRI (1995)). As mentioned above, this approach also puts disease control within the hands of the farmer, encouraging self-reliance, sustainability and development of farm level and appropriate solutions.

Training which provides only for the identification of the pathogen (often involving complex procedures) without providing the farmer with an appropriate management strategy should be discouraged. The increasingly popular diagnostic “kits” for shrimp culture, for example, should be linked to some management advice, rather than be used solely for pathogen identification.

A systems approach can be taken in the dissemination of appropriate information to farmers. An understanding of the farming system will allow appropriate information to be identified. An understanding of institutional linkages and where farmers obtain information from can be used to identify optimal strategies for dissemination of information.

One problem is the difficulty of making contact with large numbers of small-scale farmers, with existing manpower and resources. Whilst improvements in government services might help, efforts are warranted to explore other means of extending “messages” to farmers through more “remote” methodologies. In Thailand, approaches include radio, television, posters and other materials for shrimp farmers. Studies have shown chemical and feed salesmen are the most frequent visitors to small-scale shrimp farms in Thailand - and the source of most information on shrimp farm management (Office of the Environmental Policy and Planning, 1994). Information linkages with feed salesmen or other commercial outlets could perhaps be explored, whilst trying to avoid some of the obvious conflicts of interest which might arise in such an approach (FAO/NACA, 1995).

IMPLICATIONS FOR AQUATIC ANIMAL HEALTH RESEARCH

The adoption of systems approaches to aquatic animal health management has implications for identification of research needs and for the implementation of research projects. It is common for research scientists to set their own priorities, indicating widespread misuse of the term “demand led.” However, the importance of research being “led” by the demand of the end user (not the scientist looking for funding for research) is increasingly being recognized. This applies equally to aquatic health management research.

Aquaculture researchers are increasingly realizing the benefits of identifying research needs based on systems approaches and through talking to farmers (see Pullin, 1993). Further considerations in applying a systems approach to research include:

• more favorable cost-benefit from systems research, and research results likely to be more adoptable by farmers;

• timely and appropriate dissemination of results in a form suitable for “end users” taking into account language and educational background; and

• researchers need to consider the costs which may be borne by governments and/or farmers in the application of research results.

The systems approach goes further beyond the identification and implementation of research. The adoption of systems approaches to research requires cooperation involving multi-disciplinary teams. As the capacity of individual institutes may be limited, such an approach may require cooperation between institutes within countries, and sometimes cooperation between institutes in different countries. There are already some examples of fruitful cooperation among institutes in different parts of the world which have brought strong benefits in problem solving (e.g., that adopted in tackling epizootic ulcerative syndrome, EUS).

Some more specific areas where systems research might be undertaken include:

• environment-animal interactions, and optimal environment control strategies for low-stress, low-disease, aquaculture systems; and

• assessment and management of environmental impacts and the development of low impact systems (which retain/enhance farm profitability and sustainability).

SUMMARY

This paper discusses the application of a “holistic” systems approach to aquatic animal (and plant) health management. This approach implies an understanding of the links which lead to the occurrence of outbreaks of disease, and management of the aquaculture system in a way which reduces the stress and the risk of occurrence of disease (ADB/NACA, 1991). This approach implies on-farm and off-farm management, within ecological limits. Such approaches, particularly if more widely adopted at the on-farm level, are likely to lead to sustainable solutions to aquatic disease problems which can be adopted by farmers, and less reliance on the use of chemicals which largely treat the symptom of the problem and not the cause. In addition, research, training programs, extension and information exchange can be more effective and responsive to farmers' needs if based on systems approaches to the understanding and management of aquaculture farms.

REFERENCES

AAHRI, 1995. Health management in shrimp ponds. 2nd Edition. Aquatic Animal Health Research Institute, Bangkok, Thailand.

ADB/NACA, 1991. Fish Health Management in Asia-Pacific. Report on a Regional Study and Workshop on Fish Disease and Fish Health Management. ADB Agricult. Dep. Rep. Ser. No. 1. Network of Aquaculture Centres in Asia-Pacific, Bangkok, Thailand.

Deomampo, N.R., 1995. Farming systems, marketing and trade for sustainable aquaculture. In Report of the ADB/NACA Regional Study and Workshop on Aquaculture Sustainability and Environment. Network of Aquaculture Centres in Asia-Pacific (NACA), Bangkok, Thailand.

FAO/NACA, 1995. Regional Study and Workshop on the Environmental Assessment and Management of Aquaculture Development. Food and Agricultural Organization of the United Nations and Network of Aquaculture Centres in Asia-Pacific. Bangkok, Thailand.

Flegel, T.W., and S. Sriurairatana, 1993. Shrimp health management: an environmental approach, p. 1–48. In R.P. Subasinghe and M. Shariff (eds.) Diseases in Aquaculture: the Current Issues. Malaysian Fish. Soc. Publ. No. 8.

Office of Environmental Policy and Planning, 1994. The Environmental Management of Coastal Aquaculture. An Assessment of Shrimp Culture in Southern Thailand. Prepared for the Office of Environmental Policy and Planning by the Network of Aquaculture Centres in Asia-Pacific. Network of Aquaculture Centres in Asia-Pacific, Bangkok, Thailand.

Pullin, R.S.V., 1993. An overview of environmental issues in developing-country aquaculture, p. 1–19. In R.S.V. Pullin, H. Rosenthal and J.L. Maclean (eds.) Environment and Aquaculture in Developing Countries. ICLARM Conf. Proc. 31, 359 p.