R.B. Callinan
NSW Fisheries Regional Veterinary Laboratory
Wollongbar 2477, Australia
Callinan, R.B. 1996. Fish and molluse research in the Asia-Pacific: present status and future directions. 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. 29–40. FAO Fisheries Technical Paper No. 360, Rome, FAO. 142 p.
Abstract
Fish health research in the region currently presents enormous challenges and opportunities. In many countries, resources for disease diagnosis and research are insufficient to meet the requirements of rapidly expanding aquaculture sectors. Relatively little is known about the full spectrum of infectious and non-infectious diseases affecting fish and molluses in the region. It is essential that, for major industries, available research resources are focused on important disease-related production constraints with the aim of providing cost effective ways of reducing losses. Key issues and obstacles in the research process relating to identification of such production constraints, preparation of targeted funding applications, conduct of successful research projects and publication and extension of findings are discussed. To optimize research benefits, priority areas which should be addressed in most countries of the region include the need for more trained staff, particularly pathologists and epidemiologists, the need for improved access to scientific information and the need for improved diagnostic and research facilities.
INTRODUCTION
In many countries of the Asia-Pacific Region, the various aquaculture industries are now recognized as major forms of primary production having important economic, social and environmental impacts. The extent and intensity of regional aquaculture development, together with the usually unrestricted translocations of aquatic animals between and within countries, have led to frequent and serious outbreaks of disease. Many of these diseases are new or little understood. Moreover, in most countries of the region, the variety and pace of development of aquaculture industries have far outstripped the limited resources available for disease diagnosis and research. This situation presents both enormous challenges and opportunities to national and international agencies, to research-funding bodies and to individual researchers, diagnosticians, extension workers and aquaculturists. It is clearly essential that the limited resources available for disease diagnosis and research are used to maximum effect at regional and national levels. This paper utilizes the findings of a study of research needs for tropical aquaculture, conducted by the World Bank (1991), and a study of fish health management in the Asia-Pacific Region, conducted by the Asian Development Bank/Network of Aquaculture Centres in Asia-Pacific (1991). The paper also examines the processes whereby researchable issues are identified and, from the perspective of the senior researcher, examines aspects of funding application preparation and research project management in the current climate, with a view to identifying potential problem areas. Some practical measures to assist finfish and molluse disease diagnosis and research are also suggested.
BACKGROUND
Since 1990, there have been three specific assessments of needs for fish disease research in tropical aquaculture:
I. 1991 World Bank Study
In considering the potential contributions of science to aquaculture, the World Bank (1991) recognized a major deficiency in knowledge of pathology (including knowledge of pathogens) of tropical fish and shellfish. The study identified the following research needs and opportunities in the field of tropical fish diseases:
Short-term:
description of the clinical pathology of the tropical prawn, molluse and finfish species;
development of appropriate tissue cultures for tropical species as above;
development of monoclonal antibody technology;
development of nutritional pathology, particularly for fish meal substituted diets.
Long-term:
development of disease-resistant strains of key species;
development of comprehensive monitoring schemes of fish health and clinic monitoring system;
development of specific pathogen-free cryo-preserved gene pools of gametes transportation instead of adults, and to preserve the wild stock gene pools;
development of environmentally safe drugs;
development of bio-engineered vaccines against parasites and viruses;
understanding, and exploitation, of the specific defense mechanisms of crustace and molluses.
The study considered means whereby geographic disparities in knowledge could be overcome. It identified conditions necessary for conduct of efficiently targeted research, assessed institutional requirements and suggested a framework for inter-regional cooperation in tropical aquaculture research. The study concluded that networks involving core teams of scientists, networking organizations such as the Asian Fisheries Society, collaborative research programs and networks of research laboratories in developing and developed countries would accelerate development of tropical aquaculture research.
II. 1991 ADB/NACA Study
Requirements for diagnosis of, and research on, finfish and molluse diseases were assessed within a major study of fish health management in the Asia-Pacific Region conducted by the Asian Development Bank and Network of Aquaculture Centres in Asia-Pacific (ADB/NACA 1991). The study acknowledged that the technical needs for disease diagnosis and research within the region are diverse, and that major distinctions exist between the requirements of technically advanced countries and the requirements of countries with less developed aquaculture production.
Regional approaches to strengthening diagnosis and research
In his paper in the ADB/NACA study document, Macintosh (1991) proposed the establishment of a regional fish health management resource unit within NACA. One of the purposes of this unit would be to provide supporting information to scientists in the region. In this regard, the unit would monitor regional fish disease status, operate a networked early warning system, source information from other regions, organize workshops/information exchange, facilitate donor agency coordination and operate an expert scientist registry for fish health management. Macintosh (1991) also proposed formation of regional expert committees for fields including diagnostics, research standardization, improved research methodology and provision of reference materials for standard diagnoses.
National approaches to strengthening diagnosis and research
On a national level, Macintosh (1991) suggested that most countries in the region needed more trained manpower, better research and diagnostic facilities and information support via an early warning system. In addition, countries with less developed aquaculture systems lacked equipment, capability to manage facilities, and manpower and expertise. They needed training and expert advice, as well as information on diagnosis and research. Countries with more developed aquaculture systems were seen as needing an early warning system, more research into the study of new diseases, more research on virology, nutritional diseases and environmental factors in disease, and more research on acceptable therapy and prevention methods.
In its summary assessment of national and regional needs for diagnosis and research, the ADB/NACA study identified the following as requiring strengthening:
Regional diagnostic needs
Improved diagnostic facilities to provide a full range of services to aqua-farmers;
greater on-farm technical support, involving better diagnostic capabilities in the field as well as in the laboratory;
risk assessment of the use of chemicals and drugs for disease prevention or control;
survey of regional aquatic disease status and standardization of diagnostic methods.
Regional research needs
Upgrading the quality and quantity of research, particularly in the areas of virology, general microbiology, parasitology, clinical and general pathology, immunology, environmental chemistry, toxicology, fish nutrition, farm management and farming systems;
greater attention in research to the on-farm situation and the environmental conditions which affect fish health;
new research on the carrying capacity of environments which support aquaculture;
research into drug and chemical uses in aquaculture;
new research into the impact of diseases on molluse culture.
Recommendations
The study recommended the following in relation to diagnosis and research:
Establishment of a core group for coordination of national and regional programs
Establishment of this core group at NACA was seen as the central action for developement of fish health programs in the region. The group would be responsible for information collection and dissemination, coordination of cooperative research, establishing and maintaining regional centers of expertise and provision of assistance to national institutes.
Upgraded national fish health management programs
A national nodal center should be established in each country. The center would be the main diagnostic facility and would be linked to subnational centers for monitoring of disease status, diagnosis and training.
Establishment of a regional network
The network would support national fish health management programs through dissemination of information on communicable diseases, cooperative research and provision of specialized assistance to national institutes as required.
Requirement for a regional center mechanism
Regional centers of fish disease control, selected on the basis of commodity and discipline expertise, are required to support national centers in matters of diagnosis, technical reference and regional research.
Working groups to address specific issues
Working groups are required to address specific issues, including standardization of fish disease diagnostic methods.
Requirement for international collaboration
Collaboration is required with regional and international organizations in the development of management programs; the key role of NACA was recognized.
III. Second AFS/FHS Symposium on Diseases in Asian Aquaculture, Phuket, 1993 -
Report of the session on SIFR and the need for demand-led research, held at the Second
Symposium on Diseases in Asian Aquaculture: Aquatic Animal Health and the
Environment, Phuket, 25–29th October 1993, organized by the Fish Health Section,
Asian Fisheries Society (see Anon., 1993).
The report (see Anon., 1993) recognized that many factors contribute to the optimization of aquaculture production and that disease is one of the most serious constraints in this regard. The report had two stated objectives:
To provide a research basis for short-term benefit to a rapidly growing and very diverse aquaculture industry;
To provide a basis for stable long-term research which, although demand-led, allows basic and strategic needs to be met in addition, through sustained support over a long period.
General topics of importance in relation to constraint removal in Asian marine and freshwater finfish and shellfish culture were identified as:
Assessment of the disease status of Asian aquaculture in both pathological and economic terms
The report recommended that the impact of infectious diseases on aquaculture be measured by using standardized diagnostic methods in typical culture units to determine the identity and effects of diseases, and to estimate their economic costs in relation to mortality, production loss, feed conversion, etc.
Basic studies on defense mechanisms and immunology of the many diverse vertebrate and invertebrate species farmed, and the pathogenesis of their disease processes
The report recognized the narrow scientific base upon which the multibillion dollar aquaculture industries are based and expressed great concern at the lack of basic knowledge on host / pathogen / husbandry / environment interactions in almost all tropical aquaculture systems.
Improvement in diagnostic techniques, particularly with regard to rapid diagnosis and certification
The report recognized that equipment and skills necessary for disease diagnosis are not uniformly available, particularly in the poorer parts of the region. It recommended that conventional diagnostic capabilities be expanded. It also emphasized the need for rapid diagnostic methods such as fluorescent antibody and ELISA techniques, many of which remain to be developed for tropical aquaculture systems.
Control of diseases by systems management
The report recommended that management practices be developed to reduce environmental stress on the animals and reduce the prevalence and severity of disease. It suggested that development of new chemotherapeutic agents which are effective, do not lead to rapid antibiotic resistance and which leave minimal residues, is also required. In recognizing the concerns of many importing nations, the report recommended development of quality control procedures and methods for screening aquaculture products for pathogens and chemical residues.
Environmental impact
The report recognized the key role played by environmental factors in infectious disease causation and recommended studies to evaluate pathogen/host/environment relationships. It suggested that, by improving aquaculture management practices, stressful conditions can be reduced, thus improving survival, growth and performance.
Training
The report recognized that research results must be effectively communicated to end users. It recommended that mechanisms for technology transfer be improved. The peer-review journal system was seen as central to such technology transfer. Mechanisms for technology transfer from scientists in lead centers, both within and outside the region, to scientists working in less developed centers were identified as very important. In addition, mechanisms for transfer of knowledge and skills to extension trainers and to farmers were seen as critical.
CURRENT ACTIVITIES IN REGIONAL FISH HEALTH RESEARCH AND DIAGNOSIS
AAHRI and the South East Asian Aquatic Disease Control Project
In 1991, the Aquatic Animal Health Research Institute (AAHRI) was established in Bangkok as the base for the South East Asian Aquatic Disease Control Project, jointly funded by British Overseas Development Administration and the Thai government. The Project aims to develop AAHRI as a regional lead center through programs designed to identify and meet regional needs in diagnosis and research, as well as by disseminating information. Importantly, the Project provides opportunities for researchers to train via participation in research programs at AAHRI. Currently, Malaysia, Indonesia, Nepal, Bangladesh, Cambodia, Vietnam, Laos, Philippines and Thailand are involved. The Project also plans to conduct independently funded research projects based at AAHRI. These may include collaborative studies involving institutions within or beyond the region. Annual Network Workshops, at which research, current disease problems, training requirements and other development constraints will be discussed, are also planned.
Collaborative Research Projects
Donor agencies such as Australian Center for International Agricultural Research (ACIAR) and Japan International Research Center for Agricultural Sciences (JIRCAS) provide funding for collaborative research projects in fields including fish health. Currently, ACIAR is funding a project on epizootic ulcerative syndrome involving researchers from Australia, India, Indonesia and the Philippines. Such programs make important contributions to meeting many of the needs identified for fish health research in the region.
FURTHER DEVELOPMENT OF REGIONAL RESEARCH AND DIAGNOSTIC ACTIVITIES
While much is known about individual disease-causing organisms, relatively little is known about the full spectrum of infectious and non-infectious diseases seen in fish, and we are still at the relatively basic level of properly defining the full range of syndromes (ADB/NACA 1991). Under these circumstances, research and diagnosis on finfish and molluse health are obviously closely linked and will be discussed together in this paper.
Given the limited knowledge of fish diseases in most countries of the region, it is essential that diagnostic and research activities in the short to medium term are “demand led” and directed at identifying those diseases causing the greatest production losses and at developing sustainable control and prevention measures for them.
Steps in implementing a research program on key production constraints
The procedure outlined below represents an ideal which, even in developed countries, is often not completely achievable. Important components are currently lacking in many developing countries of the region. The procedure is presented here so that areas of need at national or regional levels can be specifically identified. The procedure could also assist senior researchers in refinement of methods currently used to identify appropriate research topics, to obtain funding and to conduct fish health research programs.
Identification and ranking of diseases/syndromes causing key production constraints in finfish and mollusc culture
In recent decades, massive production losses in aquaculture in the Asia-Pacific Region have been caused by diseases such as epizootic ulcerative syndrome (EUS) and pearl clam mortalities (ADB/NACA 1991). Losses caused by these diseases were recognized as so severe that research into control and prevention methods was immediately justified without detailed comparisons with losses caused by other diseases being necessary. However, it is highly likely that other less spectacular outbreaks of infectious and non-infectious diseases also cause significant, but usually unrecorded, production losses in regional aquaculture. It is also likely that, as national quarantine regulations are improved and enforced, research attention will turn to control and prevention of important endemic diseases. These must first be identified, and the necessary information can be gathered from at least three levels:
Fish farmers, in consultation with extension workers, are essential sources of information. They can provide information on occurrence of easily recognized specific diseases (e.g., white spot, lymphocystis), on easily recognized syndromes (e.g.., cutaneous ulcers, skeletal deformities) and on poorly defined syndromes (e.g.., suboptimal growth rates, non-specific mortalities, new diseases). Laboratory diagnosis is required for accurate identification and characterization of diseases in the latter two categories.
Diagnostic laboratories can be a reliable source of information on disease occurrence and distribution. However, to accurately identify any disease, laboratories must be staffed by adequately trained scientists. As a general signpost to the problems affecting a population at risk, the discipline of pathology has no parallel. Performing necropsies is the most fruitful approach in solving fish health problems (ADB/NACA, 1991). Therefore, as an essential minimum, diagnostic laboratories servicing aquaculture must be staffed by at least one diagnostician with expertise in pathology, including histopathology; appropriate technical support in histopathology must also be available. Scientific and technical staff with expertise in support disciplines including bacteriology, parasitology, mycology and water quality are also necessary for accurate identification of diseases at a diagnostic laboratory.
Over time, a diagnostic laboratory accumulates information which can be used to identify the relative importance, within the area serviced, of any disease as a production constraint. As part of this identification process, allowance must be made for factors which influence submission patterns, e.g., the increased difficulty of submitting suitable material from more distant parts of the area serviced.
Specialist laboratories may be available to provide support to diagnostic laboratories in disciplines such as virology, immunology, biochemistry, analytical chemistry and electron microscopy. They therefore also provide important information which can be used to identify those diseases causing important production constraints.
For each disease, information indicating its relative importance as a demand-led production constraint can be accumulated over time from the above sources and through close consultation with industry bodies and farmer representatives. Senior researchers, economists, epidemiologists and industry representatives can then rank the diseases using economic, environmental and sociological criteria. Often educated guesses must be used to estimate economic costs. It is important that such estimates are arrived at as objectively as possible.
Key researchable aspects of important diseases can then be identified and potential benefits arising from such research assessed. The cost of a key production constraint, the cost of the proposed research program and the cost of the expected control program must be evaluated against the likely economic benefits of the control program. Objectivity, rather than researchers' preferences and interests, should likewise dominate this process.
Preparation of a targeted funding proposal
Once a researchable topic has been identified, in many cases external funds will be required before a project can proceed. The preparation of a funding application is a critical and demanding process and, in many developing countries, necessary information is often not readily available. Such information includes lists of potential donor bodies, so that the application can be effectively targeted. To minimize the risk of duplication and to maximize the benefits of the program, the funding application must be based on a comprehensive and detailed literature review. Access to scientific literature may be limited or difficult to obtain, so that necessary technical information may be lacking. Competence in English and Japanese, the major languages of fish health literature, or access to competent translators, is often also limited.
Design and conduct of the research project
Access to current and past scientific literature is essential. It helps ensure that the separate experiments within a research project are designed as logical extensions of existing knowledge and that they use appropriate technical methods. Competence in English and Japanese may be a limiting factor in this regard for some workers in the region.
Much work can be wasted if experimental design is flawed. Before formal experimental protocols are prepared, it is essential that detailed consultations are held with biometricians or others with expertise in experimental design to ensure the experimental outcomes will be valid and useful.
Adequate scientific and administrative infrastructure is obviously essential if the research is to succeed. For example, in a project with an essential histopathology component and involving an experienced pathologist, major problems may emerge if technical facilities are inadequate, key consumables are difficult to obtain or the laboratory histopathology technician is inexperienced.
During the conduct of the experiments themselves, unexpected results and unforeseen problems will almost certainly occur. Access to literature is again important at this stage, as is access to experienced senior researchers who can advise and motivate. These may not be available in some developing countries of the region.
Publication of results in peer-reviewed international journals
Research results must be communicated, as appropriate, to producers, extension workers, other scientists and to government agencies. This is often done effectively within countries of the region, but there is a clear need to improve international dissemination of results. For a variety of reasons, some of which are mentioned below, much of the research on fish health in the region is never published in peer-reviewed international journals and, as a result, some of the research benefits are lost. Successful preparation of a suitable manuscript is a demanding process with many potential obstacles. An ability to write clearly and concisely in English is essential. Preparation also requires access to scientific literature, access to computerized word processing, data analysis and graphics applications. Often, specialized technical equipment, such as access to a well maintained, functional photomicroscope, is also required. Assistance in these areas is required in many countries of the region.
DISCUSSION
The recommendations of the World Bank (1991) and ADB/NACA (1991) studies, as summarized above, remain substantially valid and will continue to provide a basis for development of diagnostic and research capabilities in fish health for the region. Generally, this development is proceeding, albeit slowly, and the starting points and rates of progress vary widely between countries. The following modifications and additions to the recommendations are suggested as practical means to assist development of diagnostic and research capabilities in finfish and molluse health during this transition period:
Additional Recommendations
Diagnostic and research effort should be demand-led and focused on diseases causing major production constraints.
Because pathology plays a pivotal role in all fish disease diagnosis and in much disease-related research, appropriate training programs are urgently required to correct an acute shortage of skilled pathologists in many countries of the region.
Information support to diagnosticians and researchers is urgently required and should include ready access to scientific literature and direct access to case reference material (including kodachromes and histological sections illustrating typical cases).
An information package on all funding agencies which may support work in fish disease diagnosis and research in the region should be made available to appropriate senior researchers in each country. The package, which should be updated as necessary, should list all relevant agencies, and include information on funding policy, formats and deadlines for applications.
It is essential that expert advice on experimental design is available to researchers so as to maximize the benefits of their work.
Assistance with preparation of papers for publication in English is urgently required by many diagnosticians and researchers and would help maximize the benefits of their work. Excellent manuals are available on this topic and should be made available as necessary. Where appropriate, direct assistance may be warranted.
ACKNOWLEDGMENTS
I gratefully acknowledge the information and assistance provided during the preparation of this paper by J.R. Arthur, G. Barua, T. Hideyuki, S. Lumanlan-Mayo, I.H. Macrae, T. Miyazaki, C.V. Mohan, M.J. Phillips, C.R. Lavilla-Pitogo, B. O'Neil, M. Shariff and R.P. Subasinghe.
REFERENCES
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.
Anon., 1993. Priorities for disease research: towards minimizing losses from disease in Asian Aquaculture. Asian Fish. Soc., Fish Health Sect. Newsletter 4(2): 4–5, 10.
Macintosh, D.J., 1991. Research and Training Requirements and Opportunities. In 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. p. 549–567.
The World Bank/UNDP/CEC/FAO, 1991. Tropical Aquaculture Development: Research Needs. World Bank Tech. Pap. No. 151. Fish. Ser. The World Bank. Washington, D.C.
