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Artificial Recruitment and Transplantation

W.J. McNeil
K. Sandercock

Panel Members

W.J. McNeil:Artificial recruitment and transplantation of anadromous species
V.G. Jhingran:Improvement of fishery resources in inland waters
N. Hanamura:Improvement of marine fishery resources
M.A. Afinowi:Transplantation of molluscs to build up spawning populations
Relevant Documents:FIR:AQ/Conf/76/R.5, R.16, R.17, R.18, R.24,
/E.20, E.31, E.50, E.67, E.71, E.75

Artificial recruitment and transplantations have been attempted in different parts of the world for varying reasons. Whether undertaken with a view to increasing the stocks of selected species, to resuscitate the stocks of overfished or environmentally altered water bodies, to fill an ecological niche or to utilize more fully a certain biological resource, such attempts have had a more or less similar history. They have faced much scepticism and, due to inadequacies of technology and lack of support for undertaking activities on a scale required for worthwhile results, many of them were initially considered unsuccessful. But with the improvement of techniques and the implementation of sustained large-scale operations the benefits of well planned artificial recruitment and transplantations have become more widely recognized.

Sea ranching of anadromous species

The most spectacular results so far have been achieved in the “sea ranching” of anadromous species, particularly the salmons. Their strong homing behaviour during spawning migration provides a self-herding mechanism to facilitate harvesting. While at sea, some of the anadromous species undertake trans-oceanic feeding migrations. They convert plankton which is typically scattered within a very large volume of water into a form of protein which can easily be harvested and processed for human consumption. The technology for artificial recruitment of a number of anadromous species is already well advanced and is undergoing further steady improvement. They have the added advantage of being generally high-priced species.

Recent experiments in salmon sea ranching in Alaska have yielded returns of between 15 and 30 adults per spawner, which shows that artificial recruitment can be 5–10 times more efficient than natural recruitment. The profitability of salmon sea ranching has also been very well demonstrated in Japan. Progressive commitment of chum salmon (Oncorhynchus keta) to the hatchery system has eliminated the need for wild spawning areas; has increased the harvest by reducing to a minimum the number of fish required to sustain the subsequent cycle and has at the same time resulted in a doubling of the survival rate. It has been estimated that if 500 million artificially-propagated fry produced at a cost of Yen 500 million were allowed to ranch in the North Pacific, in three or four years the expected yield would be about 10 million chum salmon, valued at over Yen 10 000 million. With improvements in the rate of return further increases in yield can be expected. Although much of the progress relates to the salmons, sea ranching of the sturgeon is also growing rapidly in the U.S.S.R. and Iran.

The opinion was expressed that sea ranching of Pacific salmon and possibly other anadromous species is in a period of exponential growth. Private sea ranching has been legalized in some of the states of the U.S.A. Plans are underway for the expansion of public hatchery facilities and countries like Japan and the U.S.S.R. are planning joint ventures for artificial recruitment. Southern hemisphere countries like Chile are supporting initiatives for the introduction of salmon into their waters. As the contribution from artificial recruitment increases, harvesting rights of such stocks will become an increasingly important issue.

It is not too soon to consider the capacity of marine nursery waters to grow anadromous species. Many states will be competing for rights to graze anadromous fishes in “open range” which has a finite capacity to grow fish. The problems of establishing and protecting the grazing rights will have to be solved.

Transplantation of anadromous species provides potentially-attractive benefits, but there are associated risks which also must be fully recognized. Maintenance of genetic diversity in populations which are propagated artificially is a question which could be very important to the long-term success of sea ranching. Unfortunately, this question has been virtually ignored by research agencies. Decisions to undertake selective breeding should be based on a thorough understanding of potential loss of genetic diversity and the consequence of this loss to growth and survival of fish released into natural waters.

Conservation of wild populations could become more difficult where wild and artificially recruited fish intermingle in a common fishing ground. Wild populations of salmon in Alaska, for example, can sustain 60–70 percent rate of exploitation on the average, but there are indications that artificially-recruited populations can support 90–95 percent rate of exploitation. A fishery managed to harvest artificially-recruited populations would, under these circumstances, cause the rapid destruction of naturally-recruited populations. These and a host of other technical and socio-economic problems have to be faced.

Much of the discussion in the session centred around ocean ranching of salmon in temperate and sub-arctic areas of the world. The possibility of developing similar ranching operations in the tropics has to be considered. It was suggested that FAO should undertake the preparation of an inventory of tropical anadromous species, some of which may be suitable for a second-generation level of fish culture activity.

Improvement of inland and marine fishery resources

Transplantation and artificial recruitment in inland waters have in a large majority of cases been undertaken in response to the needs and opportunities created by man-made alterations to the environment, such as river basin development and construction of dams and artificial water bodies. Transplantation or stocking is resorted to to replace or augment affected stocks of fish, as in the case of migratory species, or to develop the fishery resources of reservoirs formed by dam construction. There are many examples of successful transplantation and stocking of inland waters. Chemical treatment of lakes to remove undesirable species followed by stocking with commercially-important species has become common practice in some countries. The U.S.S.R. implements a vigorous transplantation programme including the introduction of fish food organisms. Stocking has assumed considerable importance in the fisheries of Asian reservoirs.

As far as the marine environment is concerned transplantation of molluscs, especially oysters, has occurred on a large and worldwide scale. Due to the sedentary nature of these organisms the chances of success in such transplantations are much higher. The current attempts at artificial recruitment of shrimps in Japan have already been reviewed in Session II (Section 2). Considerable efforts are now underway in Japan to develop different types of culture-based fisheries.

In general discussions on the subject of transplantations, it was recognized that many transplants have been motivated by the desire to acquire known commercial species. Frequently this has been done at the expense of indigenous species which may have been equally suitable. It was recommended that FAO and other agencies encourage the development and use of indigenous stocks and discourage the casual approach to transplants with their attendant hazards. Introductions and transplantations are often made to fill the so-called “vacant niches”. It was suggested that these niches may be vacant only in our ignorance.

Transplants can generate extensive social and economic benefits, but this should be done with caution and proper assessment of the impact of the introduced species on natural stocks. The dangers of fortuitous introduction of pests, parasites and diseases through careless transplants were repeatedly emphasized in the session and reference was made to the guidelines formulated by the International Council for the Exploration of the Sea (ICES) for transplantation. It was suggested that FAO should consider worldwide dissemination of this document to provide a basis for the establishment of acceptable codes of practice. The establishment of an independent board, to review all proposed transplants and advise on their acceptability, was also suggested.

Legal, Social and Economic Aspects of Aquaculture

T.J. Cracknell
W. Krone

Panel Members

T.J. Cracknell:Legal problems of expanding aquaculture industries
G.M. Gerhardsen:Social and economic aspects of aquaculture in integrated rural development programmes
Y.C. Shang:Comparative economics of different types of aquaculture
V.R. Pantulu:Conflicts and comparative economics of aquaculture with other forms of land and water use
R. Ramírez Granados:Social problems affecting aquaculture development
Relevant Documents:FIR:AQ/Conf/76/R.3, R.6, R.8, R.16, R.17, R.21, R.22, R.27, R.33, R.36, R.37
/E.10, E.20, E.21, E.53, E.54, E.56, E.58, E.64, E.71, E.75, E.80, E.82

Legal and institutional aspects

There are five main groups of legal issues affecting aquaculture development, viz.

  1. competing demands on land and water space,
  2. water pollution,
  3. problems of administrative jurisdiction,
  4. intra-national and international transport of live fish and disease control, and
  5. financial support.

From the very outset of discussions on the subject, it was recognized that changes in the legal framework will only come about if there is public and establishment support and this can be achieved only through the persistent and organized efforts of those concerned with aquaculture. There may often be conflicting demands on aquaculture sites as for agriculture, hydro-power, mining, capture fisheries, industries, recreation, etc. It should be possible to reconcile these, but there are many considerations to be taken into account. Comparative economics may be an important factor in decision-making, but the scarcity of comparable basic data on aquaculture economics often makes this extremely difficult. It was suggested that the opportunity cost approach may be more appropriate. Data on net returns on fish culture presented at the session showed that, at least under the conditions described in the Mekong Basin in Asia, aquaculture was much more profitable than the locally-feasible forms of agriculture. There are other over-riding factors such as social, nutritional and even political benefits that may be derived through the proposed form of development, which clearly indicates the need for integrated planning to achieve maximum national benefits.

The session recognized the need for concentration of administrative responsibility in one agency to facilitate aquaculture development in individual countries. Governments were urged to establish such integrated agencies to avoid the delays in development programmes caused by the involvement of a multiplicity of authorities. Well coordinated planning and execution of programmes would make it possible for aquaculture to play an important role in integrated rural development, particularly in low-income areas. Ambiguities relating to the place of aquaculture in national administrative machinery have to be resolved. Though there may be no specific laws on aquaculture in a country, many other existing laws are made applicable to aquaculture. The administrative uncertainties have caused much frustration to entrepreneurs who want to invest in aquaculture and the session considered it an urgent need to remove such anomalies.

The legal and institutional structures will have to be tailored to the political and socio-economic conditions in each case and due account will have to be taken of the particular situations and policy objectives in developing countries. International agencies like FAO should encourage governments to allocate water resources for aquaculture within the framework of comprehensive coastal and water use plans and ensure that aquaculture interests are represented in water resource planning bodies.

The legal problems associated with ocean ranching have already been discussed in Session IV. The hope was expressed that some international or inter-regional machinery will be established to monitor the effects of high seas ranching and to regulate fishing rights.

The worldwide concern about environmental pollution over recent years has already benefitted aquaculture in many areas. Pollution in aquaculture waters will have to be effectively controlled and aquaculture stocks protected from contamination. At the same time adequate attention has to be given to the possible pollution of the environment as a result of aquaculture. Techniques are available to prevent this and wider adoption of these techniques should be encouraged.

Socio-economic aspects

The session took note of the recent changes in development policies and the emphasis laid on qualitative aspects of growth and a more equitable distribution of income. This has resulted in greater attention being paid to the development problems of rural areas where some of the poorest people live. In this context aquaculture has received considerable attention in recent years. Aquaculture in rural areas may have the main objectives of:

  1. providing protein-rich food for the rural people at reasonable price, and
  2. generating employment for rural people so that they may have a steady and reliable source of income

These are not exclusive of the creation of export-oriented enterprises, because they can serve to improve the rural income and the foreign exchange gained would benefit the country's economy as a whole. It was also noted that some intensive aquaculture systems, whether intended to meet domestic market demands or for export, involve high labour inputs and consequently have high employment potential. The problems of unemployment and under-employment can be mitigated to a considerable extent by the integration of aquaculture in rural development plans. The problems and prospects of combining aquaculture with agriculture and animal husbandry had already been considered in Session II (Section 4). The importance of effective extension services linked to adequate and supervised credit, and marketing assistance was further emphasized during discussions on the subject.

The coexistence of small-scale operations along with industrial-type enterprises was considered by the session. There are no ready solutions to the problems faced but with appropriate planning, conflicts, if any, can be minimized. By organizing aquaculture through associations of producers or cooperatives, benefits of large-scale operations can often be obtained. This has been well demonstrated in at least some countries.

Economic comparisons of aquaculture operations are made difficult by the lack of adequate data. Intensive type of culture usually involves higher production cost, but whether it will contribute to increased income for farmers will depend on the additional income derived and whether it exceeds the additional cost incurred. It was pointed out that aquaculture is in many cases more profitable than agriculture. Polyculture generally increases production per unit area and yields more profit than monoculture, due to the relatively low fixed cost per unit of output. In the evaluation of profitability sound economic techniques have to be adopted. The “value added” estimates or “real aggregate values” currently employed in Japan were considered appropriate in most cases. In other situations the costs of producing protein from beef or farmed fish were the most important yardsticks. Because of the inadequacy of available economic data on aquaculture operations, it was recommended that more current data on production costs, demand characteristics and marketing should be collected. It was suggested that modelling could yield production functions and costs and thus reveal the optimum combination of production inputs. This would also allow better comparison with agriculture and conventional fisheries to provide the basis for decision-making in national development planning.

Strategy for Future Aquaculture Development

C.P. Idyll
P. Hjul

Panel Members

W. Krone:Financing and credit
P.A.D. Secretan:Insurance facilities for aquaculture
T.V.R. Pillay:Research and extension services for aquaculture development
C.P. Idyll:Training of personnel for aquaculture development
G.I. Pritchard:National aquaculture development planning
Relevant Documents:FIR:AQ/Conf/76/R.7, R.21, R.25, R.33, R.36, R.38,
/E.4, E.8, E.14, E.26, E.55, E.60, E.71, E.78, E.82

National aquaculture development planning

The need for appropriate national development planning to achieve rapid and well directed development of aquaculture, which has also been stressed in other sessions of the Conference, was pointed out as a factor of primary importance. Policy-making has to be accepted as a guiding function of the entire action process. Biological and engineering sciences in many cases have progressed through the forecasting and operational planning stages to evaluate risks and to enable decision-makers to deploy financial, human and natural resources to specific tasks. But social factors have often been neglected and they also need to be subjected to the same processes of forecasting, planning and decision-making. The session commended the formulation of national aquaculture development plans through regional planning workshops organized by FAO in Africa, Asia and Latin America. Japan's aquaculture development was cited as an example of the benefits to be derived from proper planning and implementation backed by essential national legislation.

Formulation of policies and strategies has to be based on proper information and understanding. The type of information required by the policy-makers and planners may often be different from that needed by the practising aquaculturists. While recognizing the value of conferences like the present one in this regard, it was suggested that smaller advisory or similar groups should be established to assist in gathering, evaluating and interpreting basic information for planning and decision-making. The role of well organized international research and information systems in providing a basis for aquaculture forecasting and planning was specially emphasized.

In considering the general strategy to be adopted in aquaculture development, the wider application of known technology to increase worldwide aquaculture production was recognized to be vitally important. This may take the form of pilot-scale projects to test feasibility of technology transfer or large production programmes. Many developing countries would need financial support for such activities on reasonable terms.

Financing and credit

The lack of adequate financing and appropriate credit facilities are major constraints on aquaculture development in many countries. As this is a new type of enterprise insofar as the financing institutions are concerned, there is often considerable reluctance to extend support before large-scale commercial development occurs. In many areas, therefore, the immediate need is to create a suitable investment climate and to produce the economic data base for investment through pilot operations. Differences in opinion were expressed regarding the need for specialized credit schemes for aquaculture. Fisheries or agricultural credit schemes may often be able to respond to the needs of aquaculture if its specific requirements can be met, and appropriate credit supervision and linkage with aquaculture extension services can be established.

Data presented in the session showed that interest paid on capital constitutes a very large proportion of operating costs in many areas. This can have a stifling effect on commercial aquaculture development, even in the case of highly profitable systems. The major development financing agencies should take this into account when considering support to aquaculture, particularly in its early stages of development.

Financing requirements will naturally differ with the pattern and level of operations. When small-scale enterprises are to be developed there will be greater need for credit supervision and extension services. Industrial-scale aquaculture in the private sector at present tends to be more for the high-valued species and in many cases for the export market. Because of the many incentives offered for export-oriented industries, it may be comparatively easy to obtain finance for them, whereas production for domestic consumption seldom gets any preferential or even reasonable consideration.

Detailed feasibility studies and formulation of bankable project proposals were considered of special importance, and till the necessary multidisciplinary expertise for this purpose develops, international assistance will be required in most developing countries. The possibility of organizing joint ventures in order to obtain not only financing, but also management skills, technology and marketing know-how, received some attention during the discussions. The difficulties in developing joint ventures in aquaculture, especially of species meant for the domestic market, were pointed out. It was generally felt that financing of projects could be facilitated if a step-by-step approach was adopted involving research, pilot-stage operations and finally integrated production programmes.

Insurance facilities

Facilities for insurance coverage of risks involved can greatly facilitate investment in aquaculture as a stock insurance policy is a distinct advantage in raising capital. A beginning has been made in building an insurance market capable of spreading risks in Japan and the U.K. However, it is still in its infancy and considerable basic information and experience have to develop to make the conditions of insurance policies fully satisfactory and bring the relationship between premiums charged and the extent of coverage provided into balance. In this context too, the vital need for pilot projects before large-scale commercial operations are started is obvious. They will provide a clearer idea of the risks involved and the basis to prescribe premiums.

In the discussions on the subject a number of questions were raised about the cost of insurance and its influence on cost of production and the extent of coverage presently offered. An all-risks insurance was suggested to be the best form of insurance for aquaculture stocks.

Research and extension services

Research and appropriate extension services are generally accepted as essential elements in an aquaculture development strategy. Aquaculture research is of recent origin and is still in its early infancy. It was suggested that instead of trying to classify aquaculture research into basic and applied research, one may consider the different levels of research in which the prospects of success and the anticipated difficulties are of a different order. Research at a relatively simple level would be designed primarily to use known principles and derive answers to the aquaculturists' immediate problems concerning, for example, induced breeding of fish, feeding, fertilizer use, stocking densities and management practices. At a somewhat deeper level would be experiments to determine why certain practices are better than others. At a third and even deeper level would be research to determine the basic physiological and chemical reasons for phenomena, such as the inability of certain species to attain maturity in confined waters and the need for specific elements in the nutrition of particular organisms. At a fourth, still deeper and penetrating level, might be research to obtain a better understanding of the science, as for example, reproductive physiology, the nature of the genes, etc. These different levels of research may not always be conducted separately, but often may have to be undertaken simultaneously and in the same institution. What is really important is that the level of research should be appropriate for the solution of the problems faced.

The session recognized that aquaculture research has necessarily to be of a multidisciplinary nature and systems-oriented. The diffuse nature of on-going research in this field and the inadequacy of funding, facilities and expertise have already been pointed out by many expert groups. The need for re-orientation and integration of research is required both in developed and developing countries of the world. Some developed countries have already started reviewing the organization of research and identification of priority species or culture systems. Opportunities exist in these countries for contract research in the private sector and ways could probably be found to overcome the secrecy and proprietary nature of such research. As for the developing countries, a working group and later a sub-committee appointed by the Technical Advisory Committee of the Consultative Group on Agricultural Research have reviewed the research needs and formulated proposals for the establishment of regional research and training centres closely linked to selected national centres to form networks in Asia, Africa and Latin America. This proposal has been endorsed by the Regional Workshops on Aquaculture Planning organized in these three regions by the UNDP/FAO Aquaculture Development and Coordination Programme.

During discussions the session stressed the need for the promotion of systems-oriented research for the rapid development of aquaculture and recommended early establishment of the regional networks of research and training centres proposed. It was suggested that FAO should facilitate free exchange of information and expertise between research institutions. Greater cooperation between funding agencies is needed to finance organized aquaculture research and training in developing countries. It was pointed out that conferences like the present one would help funding agencies in deciding on support for specific projects. Appreciable outlays are required for building research facilities and for hiring interdisciplinary teams of scientists, but it was argued that costs for aquaculture research are not more than for research in allied sciences. With greater cooperation of funding agencies and donors it should be possible to develop the required research base for aquaculture.

Extension services

The important role of extension services in aquaculture development had also been stressed in some of the previous sessions of the Conference.

Two levels of extension work are often involved in aquaculture: one for the transfer of the results of scientific research from research centres to the field through field technicians; the other to assist farmers in the application of new and improved methods in production programmes.

The analogy of agricultural development would show the role extension services could play in a development programme, particularly in small-scale rural projects. There are at least three factors of special significance in the organization of extension services. One is the staffing and size of the extension service. Besides the advice and assistance that an extension agent may provide through periodic visits to a farm, his services have to be available to the farmer at short notice to deal with emergencies and this necessitates the provision of an adequate number of them with the required mobility of operations. Secondly, the extension service should have the required institutional backing to provide the services that the farmers may need, such as for the selection of sites, design of ponds and other culture facilities, soil and water analysis, diagnosis and control of diseases, etc. Thirdly, if the advice of the extension agent is to be implemented, very often financial assistance will be needed. So it is necessary to link extension with financial assistance and credit. This is also necessary for the proper utilization of credit. Above all, the personal qualities of the extension worker are of the greatest importance. His ability to work with the farmer, win his confidence and have the technical competence to be of real assistance, count most in the effectiveness of extension programmes. He should have access to a comprehensive information system and should have the necessary audio-visual aids to facilitate his work. The need for film strips and instructional films, besides suitably written field manuals and pamphlets, was repeatedly emphasized during the discussions. It was suggested that extension work could be strengthened by a rotation system by which jobs could be changed periodically, enabling the widening of experience of extension personnel.

Training of personnel

The shortage of adequately trained and experienced personnel is a major problem faced in the implementation of development projects both in developing and developed countries. There are many categories of personnel required for aquaculture development, but the skills required by many of them are such that “on-the-job training” would be the most appropriate way of preparing them for their tasks. Research scientists will have their basic training in the universities, but specialized training will be mainly through participation in research under the guidance of senior scientists. They should preferably receive their training in their own countries or in the region where they have to work. The network of research centres proposed to be established in developing regions will provide opportunities for young scientists to be trained in their own regions. Aquaculture technicians will need training in different aspects and types of aquaculture. For this, specialized training institutions somewhat along the lines of trade schools or agricultural schools will be required. These can more appropriately be organized on a regional basis and the proposed regional centres could fulfil this training need economically and efficiently. Training of extension workers has to be done in the countries with special reference to the systems of culture to be developed in the areas where they are expected to work.


In general, the session attempted to bring into focus the many ideas discussed in the Conference that have relevance to the formulation of a strategy for worldwide development of aquaculture leading to the provision of more food, to openings for employment and to improved incomes. It was generally felt that the lack of public understanding is one of the main constraints on creative policy development leading to a well established aquaculture industry. Through the various organized activities proposed, including demonstrations and pilot-scale projects, it should be possible to attract increased financing into the sector. Inclusion of aquaculture in integrated rural development programmes will benefit rapid economic development of rural areas and at the same time increase small-scale aquaculture enterprises in areas where it will benefit the maximum number of rural poor. Such an expanded production programme would demonstrate in a convincing manner the great potential of aquaculture and will have the spin-off effect of attracting support for research for the improvement of existing technology and the development of new techniques. It can also be expected to lead to the establishment of better facilities for training of different categories of personnel. Thus a global strategy consisting of large-scale application of existing technology for increased production, enhanced employment generation and saving or earning of foreign exchange, supported by multidisciplinary systems-oriented research to improve existing technologies and develop new techniques coupled with an intensive programme of training of core personnel, can in the next two to three decades result in very appreciable development in this sector. All these can become possible only if governments and international agencies give high priority to aquaculture and provide adequate support. It was therefore suggested that the Conference should adopt a “Declaration on Aquaculture” and the Conference Drafting Committee was asked to prepare one for adoption in a later session.

Referring to the need for massive assistance required for the implementation of aquaculture programmes in developing countries, the session suggested that some suitable means of frequent consultations between bilateral and multilateral donor agencies should be established so as to enable the best use of funds and facilities available.

Problems of Vertically-Integrated Aquaculture Industries

H.H. Webber
P. Riordan

Panel Members

H.H. Webber:Problems of large-scale aquaculture industries
T.J. Cracknell:Problems of vertically-integrated aquaculture industries in Western Europe
P. Briggs/J.W. Avault:Problems of vertically-integrated aquaculture industries in the U.S.A.
I.S. MacFarlane:Role of insurance in large-scale aquaculture
Relevant Documents:FIR:AQ/Conf/76/R.1, R.4, R.21, R.25, R.39,
/E.8, E.19

Problems of large-scale vertically-integrated aquaculture

Vertically-integrated aquaculture (VIA) systems were described as “those comprehensive systems which are centrally managed so that all the components of the system, from the input of energy from the sun to the final sale of the product in the market place, are coordinated and kept in balance”. New problems are engendered and many old problems become more critically significant as aquaculture evolves from the small-scale fish farms into large-scale agri-business generally motivated by monetary profit. All vertically-integrated enterprises need not be large and there are many examples of small but well integrated operations in this sector. But often because of the need to balance the operations of a processing plant or the need to assure quality maintenance, it becomes necessary to achieve economies of scale which in turn lead to large enterprises. They are generally in the private sector and under corporate ownership. This is, however, not essential, and could be controlled by contract or in fact completely owned by cooperatives or other collectives.

It was suggested that the long-term future growth of world aquaculture may come from VIA, but it faces a number of problems. Small scale, static demand, limited acceptability, high price elasticity, preservation, processing and distribution, competition from other aquafoods and other protein foods, were listed as some of the problem areas originating in the market. VIA enterprises gain their primary justification from the demands in the market place. Vertical integration actually proceeds backward from the market through to processing and production. Besides the market-related problems there are also a number of biological problems which are functions of large-scale, high-density, sophisticated technology.

Although most VIA enterprises are capital-intensive rather than labour-intensive, their successful operation depends largely on the availability of appropriate manpower. The lack of a pool of adequately trained and experienced personnel is a critical problem. An aquatic-animal-husbandry business manager should have, besides sound business sense and knowledge, an awareness of the biological processes on which the production is based and be able to respond and find solutions to unpredicted changes that may occur. Such managers are unfortunately rare and the assistance of a team of specialists that he would need in managing such business is difficult to come by.

As discussed in other sessions, legal and institutional constraints specially affect large-scale aquaculture enterprises. Surveillance and security become more of a problem in large-scale aquaculture than in subsistence or family farms.

Partly as a consequence of some of the above difficulties, many aquaculture ventures have been unsuccessful in enlisting the necessary investment capital. There is a great reluctance on the part of venture capitalists to commit sizeable equity funding to new aquaculture ventures. It was reported that a more frustrating factor is the highly conservative attitude of development bankers and venture analysts employed by them, who demand such high degrees of assurance and guarantee that it becomes difficult to negotiate a reasonable loan capital. The scarcity of hard economic data based on experience has been the main cause for this. It was therefore proposed that a number of pilot-scale aquafarming operations of the industrial type should be conducted in various environments based on selected culture systems and species, in order to generate sufficient economic data to establish credit-worthiness of the ventures.

Problems of VIA industries in Western Europe

A main factor determining the level of integration in Europe, as elsewhere, is the state of technology for the culture system or the species. Enterprises investing in R & D for new farmed species will be involved in all stages of the farming process. On the other hand, in well established farming, such as for trout, the farmer relies on proprietary feed and often on specialized egg and fry suppliers.

Chicken farming in Western Europe is a good indicator of how vertical integration may develop in aquaculture. Escalating capital requirements due to industrialization made it impossible for chicken farming enterprises to rely on the vagaries of the market and this led to a high degree of vertical integration. Another influence on the development of vertically-integrated farming concerns is the structure of distribution channels which varies considerably within Western Europe. In countries like Germany and the United Kingdom where multiple stores groups are dominant, the centralized packing departments require pre-packed processed products. Regular supplies of farmed fish of agreed specifications are generally possible only through integrated farming and processing. Integrated concerns can ensure quality control and build up market reputation for the products.

One of the major limiting factors to vertical integration in Western Europe is the location and ownership of suitable sites. Owners of sites having favourable characteristics like access to waste heat or water of intermediate salinities or constant temperature, are increasingly interested in participating in exploiting the fish farming potential. This results in joint ventures with partners having different objectives and creates problems in achieving vertical integration.

Political considerations and national policies have an over-riding effect on integration and even the development of industrial-scale aquaculture production. The urgent needs are appropriate governmental action to facilitate the acquisition of suitable sites on reasonable terms and adequate political support for economically viable large-scale aquaculture development with the required degree of vertical integration.

Vertically-integrated aquaculture industries in the U.S.A.

Social, economic and administrative climates in the U.S.A. were considered to favour the development of vertically-integrated aquaculture. The highest degree of integration has so far been achieved by the Pacific salmon and shrimp culturing industries which tend to be owned and operated by a relatively small number of companies. Trout, oysters and exotic fish producers do not in general have a very high degree of vertical integration. The session touched upon some of the problems faced by the catfish farming industry, such as the lack of orderly marketing with a good part of the production going to the sports fishery, inadequate statistics, poor communications between the industry and scientific groups and overlapping jurisdiction in several agencies; and referred to the advantages to be derived from unified direction at the federal level.

Even though small-scale enterprises will persist, indications are that larger companies will play a key role in the aquaculture industry of the future in the U.S.A. They are expected to invest considerable amounts of money in research and development. Regulations by the Environmental Protection Agency may enhance rather than inhibit the development of vertically-integrated enterprises.

Role of insurance in large-scale aquaculture

Large-scale, vertically-integrated aquaculture has been described as a high risk enterprise. How risky it is in comparison with other similar food production enterprises has yet to be determined. Besides biological or insurable risks, there are also commercial risks associated with marketability of the product.

The biological hazards or the risk of mortality can be minimized through improved husbandry, better management and appropriate insurance cover for non-predictable and catastrophic losses. Mortality caused by events external to the fish farm and outside its control may in general be insurable. Although at present such cover is confined to certain species (trout, salmon and oysters), insurance should be available for other species as well. Extension of insurance to other species and culture systems would become possible when the necessary data on which underwriters can base an assessment of the risk involved becomes available. Such data are not easily available and it is therefore an urgent need to collect adequate data required for the proper assessment of mortality risk in existing aquaculture ventures.

A second category of mortality risk originates from the farm itself, caused by husbandry and management faults. Such risks are unlikely to be insurable as the administrative costs involved in the settlement of numerous small claims for frequent small losses that occur will result in less attractive premiums for cover. Intensive training for operatives on fish farms, as well as those who are responsible for site selection, farm design and direction of farming operations, appears to be the most effective way to minimize risks of this nature.

In the discussions relating to risk management the importance of on-site pilot studies was further highlighted. It was pointed out that much of modern aquaculture is on the “learning curve” and it would be unreasonable to insure bad management. A suggestion was made that FAO should consider the possibility of developing an insurance formula.

The subject of risk as it relates to investment needs was also discussed. It was suggested that pilot studies should normally be financed by governments in order to determine the scale of investment required and the benefits to be derived. At that point, private investment can decide the size required for economic viability and the financial community can reasonably judge the credit-worthiness of the enterprise.

Culture of Algae and Seaweeds

Y. Saito
M.S. Doty

Panel Members

I. Neish:Status and future of seaweed culture
Y. Saito:Algae culture techniques
Relevant Documents:FIR:AQ/Conf/76/R.1, R.14,

Seaweed production at present is over 16 percent (in weight) of the world's total aquaculture production and a 10 percent annual increase is expected until the total production triples to reach saturation in respect of present demands. In order to understand the role of aquatic agronomy as an integral component of aquaculture development, one has to take into account also the aquatic algae and other primary producers consumed by fish and shellfish. It is estimated that over 600 million tons of aquatic algae are consumed as food by cultured fish and shellfish. Aquatic plants also provide critical substrata, shelter, pests and fouling. Their management involves utilization of ecological, biological and physiological information to produce crops and reduce those that are not wanted. It includes provision of appropriate substrata and fertilization. Achieving favourable balances between these agronomic elements and the animals is the objective of such management.

In Japan the major use of seaweeds is as delicacies in the national diet. Porphyra, Undaria and Laminaria are the three main groups with many others being used variously in lesser quantities. The trend has been from wild crop harvesting, through improvement of its management, to highly technical agronomic procedures. While Porphyra and Undaria are in oversupply at present the demand for Monostroma and Laminaria is growing. The use of Eucheuma is expected to increase at least 10 percent per year in the tropics.

In general the discussions in the session stressed the need for development of more productive strains, as suitable areas for cultivation are rather limited. Control of disease, fertilization to improve growth and other intensive culture practices are being increasingly incorporated into agronomic management. Significant improvements have been achieved in the production of Laminaria, Gelidium, Chondrus, Macrocystis and Undaria. Improving the environment seems to be the most common management practice in vogue now, as for example, broadcasting Caulerpa and Gracilaria cuttings on favourable bottoms; fastening cuttings of Gracilaria and Eucheuma to lines or nets; seeding spores or zygotes onto nets or lines in the case of Porphyra, Undaria, Monostroma and Laminaria, and establishing artificial substrates of boulders or concrete blocks in the case of Gelidium and Gloiopeltis.

Part of the environmental management is aimed at achieving a productive balance between the desired grazers and desired seaweeds. Two outstanding examples of such balance between animals and algae are the one between abalone and kelp, and between Macrocystis and its principal herbivore the sea urchin, Strongylocentrotus. Protective cages over seedling algae, chemical control of the animals and proper seeding intensities are the most common practices employed at present.

Discussions on the low and declining demand for certain seaweeds and the future of aquatic agronomy led to a consideration of the food value of algae and other seaweeds. While most of those used for human food at present are largely of only supplemental value and provide trace elements and growth factors rather than calories, some like Spirulina are reported to contain as much as 70 percent protein on a dry weight basis. Most seaweeds eaten by man are consumed in quantities too small to be significant in terms of calorific value. However, in view of the basic importance of plant proteins in animal aquaculture and the possible increased consumption of more nutritive algae by man, it will be useful and necessary to study the food value of macro- and micro-algae.

Clone selection and breeding have resulted in significant increases in the quality and quantity of seaweeds produced by culture. The high-yielding Porphyra strains in Japan and Eucheuma strains in the Philippines are examples of successful clone selection. The production of superior strains of Laminaria japonica, e.g. the Hai Ching strain, through breeding, may have been very significant in extending the production of this genus southward to Hainan (China) and achieving an estimated production of perhaps 300–500 dry tons per year.

One area of investigation that requires special attention is algal diseases caused by micro-organisms and physiological conditions. As the intensity of cultivation increases both types of malady occur but neither is well understood.

A major constraint on seaweed culture is the deterioration of water quality. Studies on the accumulation of heavy metals, radionuclides and toxic organic materials by algae should be encouraged so as to enable the design of appropriate systems. The introduction of aquatic agronomy in selected geographic areas where it is not practised now could be very beneficial. This will require the identification of suitable new sites for the desired algae, their physiological and other requirements and the problems of their transplantation.

Oyster Mortalities and Their Control

C.J. Sindermann
W.N. Shaw

Panel Members

C.J. Sindermann:Large-scale oyster mortalities
P. Korringa:Oyster mortalities in Europe
A. Koganazewa:Oyster mortalities in Japan
D.J. Andrews:Oyster mortalities along the Atlantic coast, U.S.A.
K. Chew and J.B. Glude:Oyster mortalities along the Pacific coast, U.S.A.
Relevant Documents:FIR:AQ/Conf/76/R.2, R.16, R.34

Large-scale oyster mortalities

Large-scale oyster mortalities of epic proportions have occurred during much of this century and in some areas still continue to occur. During the past two decades catastrophic mortalities have occurred in Japan, Europe and North America. The United States-Japan Cooperative Natural Resources (U.J.C.N.R.) Panel on Aquaculture considered this problem at its meetings in 1974 and 1975 and the findings suggested that in view of its worldwide importance, a review of world experience in determining the cause of such mortalities and measures adopted to control them would be of considerable value. This special session was organized for this purpose in response to the suggestion of the U.J.C.N.R. Panel on Aquaculture.

Mass mortalities can generally be considered as exaggerated forms of natural mortality, usually distinguished by being of rapid onset, affecting a large proportion of the population over an extensive geographic area, and being of relatively short duration. Many mass mortalities of oysters undoubtedly result from interactions of environmental and biological factors; only a few have been clearly associated with a single over-riding causal factor; and of these few, disease has usually been the identifiable cause.

Natural mortality of oysters can be considered as of three types:

  1. “background mortality”, a continuous, often unnoticed but very significant reduction in numbers of individuals at any stage of the life history,
  2. localized mass mortalities, affecting restricted geographic areas and killing up to 100 percent of the populations in those areas, and
  3. widespread and extensive mass mortalities, affecting large geographic areas and reducing oyster production significantly.

The session concentrated its attention on the third type of mortality.

It is difficult to draw any rigid dividing line between background and mass mortalities, but as a very rough criterion, maximum “background mortality” in many oyster populations can be considered to be 10–15 percent in a single year (exclusive of larval and spat mortality); anything above that figure should probably be termed a mass mortality. This estimate is, of course, variable from area to area; some oyster growers become alarmed if annual mortalities exceed 5 percent, while others tolerate annual mortalities approaching 50 percent.

In general it may be said that some of the mass mortalities are clearly related to epizootic levels of an infectious agent. Some seem related to environmental factors and possibly to physiological stress, but in some other cases probably an interaction of infectious and non-infectious processes are involved. The crucial fact is that almost 75 percent of widespread mass mortalities must be categorized as of unknown origin.

Oyster mortalities in Europe

A review of oyster mortalities showed that several cases of catastrophic losses of stocks have occurred since the introduction of modern oyster farming in Europe more than a century ago. The known causes of these are hydrographical or biological. Severe winters have caused large-scale mortality of sub-tidally grown oysters due to water temperature remaining below freezing point for extended periods. The most severe case in the Netherlands was in 1962–63 when the temperature remained at about -1.6°C for up to 71 days. The weakened oysters were not able to keep their valves tightly closed and in rough weather silt and sand could intrude inside the valves. The effect of severe cold on intertidally grown oysters is different. In Brittany (France) the spat on the tiles dried out at the windward side of substrate tiles after several days of strong freezing wind. In Arcachon (France) it was observed that mortality of Portuguese oysters (Crassostrea angulata) exposed at low tide occurred due to freezing of the water contained in the porous “chalky” deposits in the shells. A special case of high mortality was observed in the fattening ponds (claires) in the Charente Maritime in the long and dry summer of 1947 caused by intense evaporation in combination with low spring tides, which increased the salinity to dangerous levels.

Among losses ascribed to biological causes is the devastating mortality of flat oysters (Ostrea edulis) that swept along European coasts from 1919 to 1923, beginning in Taranto (Italy), spreading via France and England to Germany and Denmark. It totally destroyed several flourishing oyster beds and it took many years before stocks resistant to the attack were re-established. Based on the information collected at that time it can now be concluded that the mortality was most probably caused by a microbial disease.

In the Netherlands the so-called shell disease killed many flat oysters (O. edulis) and left others badly deformed and lean in the years following 1930. As a result of a decade of research it was discovered that the disease was caused by the fungus Ostracoblabe implexa, normally living in old shells in symbiosis with perforating algae. A fungicide could be used to control the fungus in the mycelium stage. Dredging away of old cockle shells in 1948 and 1949 led to drastic reduction in the infection.

Another major oyster mortality due to biological causes occurred among Portuguese oysters on the Atlantic coast of France south of the Loire river in 1967. This was considered to be a gill disease and tentatively ascribed to Labyrinthomixa, but definite proof is still not available. Since then catastrophic losses have occurred on the southern part of the Atlantic coast of France, especially in the years 1971 and 1972. These were shown to have been caused by a virus. Whether the so-called gill disease was also caused by a virus is not clear. Large numbers of the Pacific oyster (Crassostrea gigas) were imported to replace the stocks lost by this disease.

Another recent serious case in France was the mortality of flat oysters (O. edulis) in Brittany in 1971, which quickly spread from the estuaries Aber Wrach and Aber Benoit to the east and south. The disease was diagnosed to have been caused by a haplosporidian parasite, probably spread through a vector.

Oyster mortalities in North America

The east coast of North America has experienced epizootics of oysters caused by pathogens for several decades. The earliest occurred in Prince Edward Island, Canada, beginning in 1915 and spreading to much of eastern Canada in the 1950's. It was presumed to have been introduced with New England oysters in 1914, but no definite pathogen has been found in 50 years. Resistance was slowly attained by survivor stocks.

The warm-season disease found in the Gulf of Mexico about 1950 is caused by the pathogen Dermocystidium marinum, which is now being renamed. The disease may be controlled by early harvesting, isolation of beds and cleaning of all oyster beds where old oysters serve as disease reservoirs.

In 1957 a new pathogen decimated oysters in Delaware Bay, and it spread to Chesapeake Bay in 1959. It has persisted for nearly 20 years without reduction in infective pressure. Resistant oysters were developed in Delaware Bay by selection of wild populations and in Chesapeake Bay by hatchery breeding of survivors of epizootics and subsequent selection. The pathogen, a haplosporidian of the genus Minchinia, may be controlled by the use of selected genetic strains. This offers a method of preventing epizootics caused by other closely-related pathogens, e.g. sporozoans now found in Korean, Australian and Western European oysters. A second Minchinia species has been found in high-salinity waters of Virginia which kills 25–50 percent of oysters in about one month from mid-May to mid-June. Early harvesting at two years of age is now considered the best method of control.

Pacific oyster (C. gigas) mortalities of major proportions occurred during the 1960's and in the year 1970 along the Pacific coast of the United States. These mortalities occurred during summer months of June through September and so rising water temperatures have been suspected as one of the conducive environmental factors for these mortalities. Experimental studies have shown that enrichment of the sea water with organic nutrients accelerated bacterial production and subsequently increased the mortality rate at temperatures above 18°C. Consistently high numbers of bacteria were isolated from the blood and pericardial fluid of moribund oysters.

The majority of vibrios isolated during summer periods appeared to be of the Vibrio anguillarum type. This species is a major cause of infection in fish and has been incriminated as a cause of mortality in oysters. Use of antibiotics such as TM-50 does show in most cases a lessening of mortalities under passive innoculation.

Preliminary studies have shown that progenies of oysters surviving large-scale mortalities have significantly higher survival rates. Isozyme tests are being utilized to determine genetic differences between surviving stocks of challenged oysters and natural stock. Work in the University of Washington has resulted in the identification of the enzyme AAT (Aspartate aminotransferase) in the early survivors from laboratory challenges.

Oyster mortalities in Japan

From an examination of the history of oyster culture in Japan and the successive improvements and innovations oriented to intensifying production, it has been noted that mass mortalities have become frequent with the adoption of intensive farming methods, starting in 1945. They occur more often in the southern part of Japan and particularly on the east coast. Matsushima, Hamanako and Hiroshima bays were most seriously affected in 1961 and 1969. In Matsushima Bay mortalities were 40–50 percent.

Observations show a number of common features characterising these mortalities but no single factor can be identified as the causative agent. The most recent observations are that:

  1. rapid sexual maturation and massive spawning under high temperature in eutrophic conditions cause heavy physiological strain and metabolic disturbance leading to mortality, and
  2. bacterial invasion occurs in affected oysters in different parts of the body, including the spaces between glycogen-bearing cells, but bacteria do not appear to be the lethal agents.

Oyster growers in Japan adopt two methods to prevent heavy gonad maturation and spawning. One is the use of hardened seed, the other the placement of oysters in nutritionally-poor areas during the period of maturation followed by a move to nutritionally-rich places in late summer. Both these procedures serve to slow down gonad maturation and metabolic imbalance.

In discussions it was suggested that the possibility of a pathogen being the causative agent should not be abandoned as long-term studies on other oyster diseases have revealed the role of pathogens.

While considering the geographic distribution of mass mortalities some other instances were cited. For example, the mass mortality of pearl oysters (Pinctada martensii) on the Red Sea coast of Sudan in 1969 has affected the livelihood of a large number of people along Dongonab Bay. The cause of the mortality has not been found and assistance in carrying out the necessary studies was sought. Reference was also made to mass mortalities that occurred in winter in Australia.

Over ten years of research on Malepaque disease in Canada have not yet succeeded in finding the causative agent, though there is some indication that it is a Labyrinthucid.

In concluding the session it was noted that in the last 75 years in 75 percent of the cases of mortalities it has not been possible to isolate the cause. This points to the need for concerted efforts and international cooperation in solving the problem. It was suggested that an international group of experts should be assembled to critically review all the basic data available with a view to facilitating future diagnosis of diseases. An international agency like FAO should consider sponsoring a team to be made available at short notice for detailed investigations when mortalities occur. Such activities will have to be coordinated through a competent working group.

International Aspects of Disease Control in Aquaculture

P. Ghittino
G.I. Pritchard

Panel Members

P. Ghittino:International aspects of disease control
C.J. Sindermann:Control of diseases in marine aquaculture
S. Sarig:Control of fish diseases in inland aquaculture
K.E. Wolf:Status of research on diseases of cultured fish
Relevant Documents:FIR:AQ/Conf/76/R.2, R.16, R.32,
/E.1, E.11, E.19, E.23, E.39, E.53, E.59, E.63, E.67

Control of diseases in aquaculture

While pathogens and hosts may generally be in balance in nature, this balance is often upset very much in favour of the pathogen under culture conditions. The imbalance is accentuated with the degree of intensity of culture methods. Infections and mortalities have led to considerable losses in freshwater, brackishwater and marine aquaculture in different countries. Large-scale mortalities suffered by oyster stocks had been discusses separately in Special Session III. With the expansion of aquaculture international exchange of cultivable aquatic animals in different stages of their life history is expanding rapidly, with attendant hazards of fortuitous spreading of disease.

As the knowledge of infectious diseases is basic to controls, either on a national or international basis, the session attempted a general review of the present state of diseases and their control in inland and marine aquaculture, including ongoing research in this field.

During the last decade considerable advances have been made in the diagnosis and control of many diseases affecting aquaculture stocks. Generally speaking, aquaculturists are now better able to identify the harmful organisms and to take effective measures to control infection and mortality. Through the use of advanced techniques of histology, identification of pathogenic organisms and use of medicated feed, it has been possible to control many diseases of bacterial origin. Although a number of viral diseases have been identified in freshwater culture, very little progress has been made in their control. As most diseases are caused or enhanced by poor environmental conditions and defective management, there is now a greater recognition of the need for effective environmental control to prevent disease.

The trend in recent years has been to look more and more toward the overall health status of aquatic organisms and to emphasize prevention of disease, paying increasing attention to environmental stress which is conducive to the occurrence of disease. Immunology is fast emerging as an important means of disease control, particularly in North America, but chemotherapy is greatly constrained by the cost involved and drug control regulations. Nevertheless, much progress has been made in Japan in nitrofuran chemotherapy. It was noted that a large body of valuable information has accumulated on the subject, much of which has not been published. The session recognized that it would be most useful if such information could be compiled and published in the form of a handbook of diagnosis and control of diseases in aquaculture. This need is particularly relevant to marine aquaculture.

International aspects of disease control

As already noted, the hazards of spreading communicable diseases through introduction and transplantation of aquatic organisms are becoming increasingly serious with the expansion of aquaculture. Although all importing countries are anxious to prevent the transmission of disease, there are considerable difficulties in establishing health histories or ensuring that the stock is free from disease. The session reviewed the action taken by the International Office of Epizootics (OIE), European Inland Fisheries Advisory Commission (EIFAC) and FAO to formulate an international convention for the control of selected communicable diseases, based on inspection at source combined with certification. A revised version of the first draft of the convention will be examined at a Government Consultation to be organized by FAO/OIE in January 1977 in Paris. The session stressed the need to finalize the convention as early as possible.

In order to extend the control measures to other diseases as well, it is necessary to develop acceptable diagnostic techniques and establish an adequate number of reference laboratories. This need applies to diseases of both freshwater as well as marine species, but it is greater for marine aquaculture. The session suggested voluntary restrictions on the distribution of virulent pathogens for research purposes, because of the dangers of their escape.

Genetics and Genetic Improvement in Aquaculture

R. Moav
S.R. Malecha

Panel Members

G. Gall:Fish genetics and genetic improvement
T. Gjedrem:Breeding schemes
T. Brody:New methods for fish breeding
Relevant Documents:FIR:AQ/Conf/76/R.9,
/E.48, E.51, E.61, E.63, E.74, E.78

Fish genetics and genetic improvement

The branch of genetics that is of major interest in aquaculture is “population genetics and animal breeding”, which is based on the quantitative nature of the inheritance of most of the significant characters and the subtle inter-relationship that exists between the genetic make-up of an individual and its environment. The basic theory for fish breeding is already available from allied disciplines like animal breeding, and what needs to be determined as far as fish breeding is concerned is the most appropriate breeding scheme for specific objectives and particular species.

A problem often faced by the aquaculturist is defining or selecting an environment suitable for a culturable species. A genetic approach to the problem would be based on the concept that the genetic make-up of the species has been observed to be responsive to a particular environment and if we succeed in culturing it in different environmental conditions it can be considered to have been domesticated. As high survival is achieved, the changes in the environment would have been met by changes in the genetic make-up of the species. The challenge of the fish breeder is to direct the genetic changes in such a way as to maximize the probability that the resulting “domesticated” organism is economically effective in culture.

Other considerations relate to:

  1. the maintenance of an adequate population size, as from a genetic standpoint the size is determined only by the number of individuals that leave progeny, and
  2. the evaluation of traits of economic value.

These determinations are not always easy.

Characterizing the nature of genetic variability and assessing the influence of environment on performance is rather complex, particularly since we cannot see or enumerate the genes but can only observe the phenotype. The phenotype represents the combined effects of all the genes that influence the trait. Consequently the nature of the genetic differences between individuals, represented by differences in their phenotypes, will depend on the nature of the effects of the individual genes. If the effects all combine in an additive manner, the trait is considered to be inherited additively and selection can be expected to be an effective breeding scheme for improving such traits. However, if the individual genes interact with each other, for example through dominance, then the trait is inherited non-additively and a crossbreeding or hybridization scheme has to be chosen to maximize heterozygosity. Examples of these approaches are described in some of the papers presented at this Conference.

Another problem in comparing phenotypes is the nature of the environmental effects, the quality of which will either be above or below average. Consequently, when two animals with different phenotypes are observed, for example different body weights, it is difficult to determine how much of the difference is genetic and how much is environmental. This could be solved by estimating the heritability which is the average or the expected proportion of the differences between individuals that is due to genetic differences.

There is no doubt that properly-designed breeding schemes can benefit aquaculture very substantially. Cross breeding or hybridization can produce quick changes, but poorly-designed programmes can be disastrous in terms of lost effort and loss of faith in genetics.

Breeding schemes

After a suitable species has been selected for culture, the next step is to find the most productive strain or breed within the species. Very appreciable differences have been found between strains in growth rate; as much as two to three times in some instances. The breeding programmes to be adopted will depend upon the type of genetic variance that dominates. As mentioned earlier, if non-additive genetic variance is relatively large, hybridization can be used effectively. Cross-breeding is simple to practise and is therefore more easy to introduce. If, on the other hand, additive variance is of importance, selection becomes the major tool and the most simple form of it is mass selection. Family selection will play an important role in a breeding scheme for fish. It will be of particular importance for traits with low genetic variance and for traits such as disease resistance, age at sexual maturity and survival. These, as well as meat quality and resistance to acidic water, have been shown to have detectable genetic variance. In order to carry out intensive family selection many families will have to be tested each year. This would require a large number of hatching and rearing units to rear the fingerlings until they can be tagged, or alternatively genetic marker techniques will have to be adopted. It is also likely that in many cases selection will have to be combined with cross-breeding. It should be stressed that testing in a breeding programme should be done under similar conditions as in the expected production environment. The problem of deterioration of F1 hybrids in breeding programmes of wild populations was raised and it was suggested that a higher catchability should be developed in the domesticated breeds so as to ensure the removal of a great majority of F1 hybrids by fishing. Introgression of genes from the domesticated into the wild population may not be a problem; on the contrary it may be possible to upgrade the wild population from the economic point of view.

There are a number of new methodologies for fish breeding, of which the use of genetic markers promises to have the most immediate application. Even though polymorphic markers are described in most edible fish species, they have not yet found common use in fish breeding. They can be effectively used for:

  1. maintenance of breed purity,
  2. lineage identification in complex crosses,
  3. management of pond space,
  4. monitoring crosses performed in the wild, in polyculture or in undrainable ponds, and
  5. study of the genetics of polygenes responsible for quantitative characters.

The session considered these various uses in the light of experimental work so far done. During discussions it was reported that the study of a large number of polymorphic electrophoretic markers in oysters did not reveal any correlation with economic characteristics. The conclusion was that markers can be useful only when samples of many thousands of individuals are tested and in the present state of technology this is impractical. Markers can still be used in breeding programmes for lineage determinations.


Reviewing the work carried out in recent years on fish genetics, it was concluded that considerable progress has been achieved in the understanding of the genetic control of economic characters of fish and in formulations of breeding schemes. Unfortunately, there is little application of the knowledge gained in practical commercial breeding programmes. Examples quoted were the prevention of inbreeding depression and higher growth and catchability of hybrid strains of carp. It has been known since 1960 that mating of closely related fish is very deleterious and since then a large body of evidence has accumulated confirming the existence of strong inbreeding depression and equally strong heterosis in fish. Yet, with very few exceptions, most fish farmers do use highly inbred stocks, when by continuous crossing of unrelated stocks this could be easily overcome. Similarly, the Chinese race of “big-belly” carp, which is reared in more than a million hectares, has a comparatively low growth rate and catchability. It has been shown that by crossing it with the domesticated European mirror carp improvements up to 100 percent can be obtained. In general it can be said, with only few exceptions, that aquaculturists are using wild, completely undomesticated organisms, a situation comparable to using jungle fowl to run a modern poultry. There is, therefore, an urgent need to utilize genetic expertise to adapt these organisms.

It was argued that the transfer of the results of genetic work is easier than other forms of technology transfer. This transfer can probably be made by breeding stocks suitable for particular situations in centres with the necessary competence and facilities, and transplanting them to areas where they are to be farmed for final testing and rearing. One exciting application suggested was the genetic upgrading and maintenance of partial heterosis in traditional farms, even those with undrainable ponds, by merely making available morphologically distinguishable stocks of a single sex from central breeding stations. The same methods may be useful to correct genetic damage caused to wild organisms that have been overfished for a long period of time.

One of the major constraints to the use of genetic techniques at present is the fact that many of the cultured species cannot be spawned in captivity. Accelerated research in this field is a prior necessity. The lack of trained fish geneticists is another constraint. Although the basic theory is similar, there are distinct differences between fish genetics and other forms of animal breeding. Genetic variability is far greater in aquaculture candidates than in other farm animals and the fish geneticist should not merely copy the standard approach of animal geneticists.

It was proposed that a manual of fish genetics containing suggested breeding programmes and fish genetic techniques should be prepared for the use of aquaculturists. Governments were urged to establish genetic research groups at centres of excellence. An international meeting on genetics in aquaculture was also considered useful.

In view of the long-term needs for preserving natural genetic variability of cultured organisms, the session recommended that efforts should be made to build up gene pools, and for this appropriate methodologies have to be developed.

Main Conclusions and Recommendations

Y. Uchimura
T.V.R. Pillay
Chairman of Drafting Committee - C.P. Idyll
Relevant Document:
Draft Summary Report - FIR:AQ/Conf/76/Rep.1

The discussions in the session were based on a draft summary report prepared by the Drafting Committee. One of the major conclusions of the Conference was that the pace of future development would depend on the priority given to aquaculture by governments, funding and financing agencies and the industry. A review of the progress in this sector during the last ten years fully supports such a conclusion. The session therefore adopted the following declaration on aquaculture to serve as a basis for policy-making in aquaculture development.

Kyoto Declaration on Aquaculture

The FAO Technical Conference on Aquaculture, assembled in Kyoto, Japan, on 2 June 1976, after a week-long review of present status, problems, opportunities and potential for the culture of fish, crustaceans, molluscs and seaweeds, declares:

  1. That aquaculture has made encouraging progress in the past decade, producing significant quantities of food, income and employment; that realistic estimates place future yields of food at twice the present level in ten years, and five times the present level in 30 years if adequate support is provided.

  2. That aquaculture, imaginatively planned and intelligently applied, provides a means of revitalizing rural life and of supplying products of high nutritional value, and that aquaculture, in its various forms, can be practised in most countries, coastal and landlocked, developed and developing.

  3. That aquaculture has a unique potential contribution to make to the enhancement and maintenance of wild aquatic stocks and thereby to the improvement of capture fisheries, both commercial and recreational.

  4. That aquaculture forms an efficient means of recycling and upgrading low-grade food materials and waste products into high-grade protein-rich food.

  5. That aquaculture can, in many circumstances, be combined with agriculture and animal husbandry with mutual advantage, and contribute substantially to integrated rural development.

  6. That aquaculture provides intellectual challenge to skilled professionals of many disciplines, and a rewarding activity for farmers and other workers at many levels of skill and education.

  7. That aquaculture provides now, and will continue to provide, options for sound investment of money, materials, labour and skills.

  8. That aquaculture merits the fullest possible support and attention by national authorities for integration into comprehensive renewable resource, energy, land and water use policies and programmes, and for ensuring that the natural resources on which it is based are enhanced and not impaired.

  9. That aquaculture could benefit greatly from support and assistance from international agencies, which should include the transfer of technology actively planned and executed, with research carried out in centres representative of various regions concerned.


The different sessions and informal working groups of the Conference had arrived at various conclusions on specific aspects and indicated future lines of action. While endorsing these and approving summary reports of the sessions, the Conference adopted the following major recommendations in furtherance of the policy implicit in the declaration above, for implementation by governments and concerned agencies.

1. Pilot-scale projects

The Conference,

Having reviewed the progress of research on aquaculture during the last decade in different countries,

Noting that considerable basic information is available on new species and systems of culture and that the application of such information for commercial production is hampered by the lack of pilot-scale projects,

Also considering that such pilot-scale projects are essential for the improvement or refinement of the technologies under development,

Recommends that governments and financing agencies support the establishment of suitable pilot-scale or model projects in order to test the technical and economic viability of the techniques for commercial application.

2. Expansion of aquaculture production

The Conference,

Taking into account the present state of aquaculture and the contribution it is already making to world production, particularly in the developing world,

Noting that there are a number of proven systems of culture that can be used for expanding production through horizontal or vertical transfer of technology,

Urges governments to give high priority to aquaculture development in national planning, and governments and private sector agencies to promote aquaculture production programmes aimed at a minimum of fivefold increase in aquafarm production in the next three decades.

Further recognizing that lack of appropriate financing continues to be a major constraint on the expansion of aquaculture, and that aquaculture can be a major means of improving the quality of life of the rural populations in developing countries,

Recommends that the World Bank Group, regional banks, national development banks, FAO Bankers Group, International Fund for Agricultural Development, and other financing agencies recognize aquaculture as a priority sector for investment and provide adequate financial support for aquaculture in developing countries, taking into full account the social values of rural aquaculture.

3. Inclusion of aquaculture in integrated rural development projects

The Conference,

Taking note of the role aquaculture, especially fish farming, has played in the past in the rural economies of many countries,

Recognizing that well planned and organized aquaculture programmes could form an important part of modern integrated rural development,

Recommends that governments give appropriate consideration to aquaculture in the formulation and implementation of integrated rural development plans.

It further recommends that funding and financing agencies provide the necessary support and encouragement for the inclusion of aquaculture in rural development projects they sponsor.

4. Production and distribution of aquaculture inputs

The Conference,

Noting that production of aquaculture inputs, especially seed, feed and fertilizers, are of critical importance in aquaculture development,

Recognizing that for a sustained expansion of the industry on an economically and scientifically sound basis it is necessary to produce these main inputs locally,

Urges governments to establish, on a high priority basis, seed, feed and fertilizer production to meet the needs of the industry.

Further recognizing that in many developing countries it is difficult to obtain the necessary pituitary material required for breeding certain species of cultivated fishes,

Recommends that FAO or a similar agency establish a pituitary bank to facilitate the procurement of adequate supplies for experimental and seed production programmes in developing countries.

Considering the need for detailed information on the nature, composition and nutritive value of available feed ingredients for the formulation and manufacture of feeds in developing countries,

It further recommends that such data be computerized with the assistance of existing Feed Ingredients Data Banks for the benefit of all countries.

5. Aquaculture research

The Conference,

Noting that future expansion in aquaculture production is expected to be achieved through transfer of existing technology, improvement of existing technology and the development of new technologies,

Recognizing that all these means of increasing production need systems-oriented, multidisciplinary research at the appropriate level,

Further recognizing that diffuse research efforts now underway in many countries could be made more productive through appropriate coordination and integration,

Recommends that coordinated multidisciplinary research on culture systems selected for major production programmes be established.

It further recommends that the regional networks proposed by the TAC Sub-Committee of the Consultative Group on International Agricultural Research and the FAO/UNDP Regional Workshops on Aquaculture Planning in Africa, Asia and Latin America (1975) be established.

It requests the donor agencies interested and involved in supporting aquaculture to provide the required level of assistance for multidisciplinary research on aquaculture through coordinated programmes.

6. Establishment of extension services

The Conference,

Noting that the lack of suitably-organized extension services is one of the major handicaps to aquaculture production programmes, especially in developing countries,

Considering that successful aquaculture as a part of integrated rural development will depend to a large extent on the provision of prompt and appropriate assistance of extension services,

Urges governments to give high priority to the establishment of adequately-staffed extension services, with necessary laboratory and technical support to meet the needs of producers.

It recommends that governments establish suitable extension workers' training centres on national or group country bases as required to meet the needs of extension personnel.

7. Training of core personnel for aquaculture development

The Conference,

Having recognized that the scarcity of suitably-trained practical aquaculturists or aquaculture practitioners is a major problem facing the development of aquaculture in many countries of the world,

Noting that the need for trained personnel is particularly urgent and important in developing countries attempting to increase food production and employment,

Considering that the two types of core personnel that require institutionalized training are the practical aquaculturists and extension workers, and that it is preferable and in most cases essential to provide training facilities in the country or the region where they are expected to work on completion of their training,

Being aware that the number of aquaculturists required in a country on a continuing basis may not justify the establishment of permanent national training programmes for such personnel,

Recommends that the proposed regional network of aquaculture centres be used for training purposes, at least initially, taking advantage of the expertise and personnel that will be available at such centres. It also endorses the proposal that the regional centres should be used for the training of aquaculturists and the national centres in the network for the training of extension workers.

8. Aquaculture legislation

The Conference,

Recognizing that absence of a legal basis for the establishment and/or expansion of aquaculture is a major constraint on aquaculture development in many countries,

Urges governments to enact appropriate aquaculture legislation facilitating the establishment of aquaculture industries and enabling the zoning of suitable coastal and inland areas for aquaculture.

It further recommends that governments make available financial and other incentives generally given to emerging industries, including provision of risk guarantees.

9. Advisory panel on aquaculture

The Conference,

Realizing the need for expanded international and bilateral assistance for aquaculture research and development,

Considering that the best available international expertise and experience should be brought to bear on the formulation and implementation of research and development projects and on the coordination of worldwide activities, including those especially emphasized in the panel discussions of the Conference,

Recommends that FAO, in cooperation with other agencies concerned, establish an Advisory Panel on Aquaculture to facilitate the implementation of the recommendations of this Conference and to advise on future aquaculture activities on a continuing basis.

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