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For orientation and for the convenience of the reader, the Background and Conclusions Sections of the Report of the Expert Consultation on Inland Fishery Enhancements1 are set out below.


The potential for enhancement of fish production from inland waters has been considered a priority area of activity by the Inland Water Resources and Aquaculture Service of FAO for some time. A number of appropriate management strategies have been identified and experience in the implementation of these strategies has been built up to varying degrees in different parts of the world through experience in field projects and syntheses of the literature.

The outcome of the Japan/FAO International Conference on the Sustainable Contribution of Fisheries to Food Security, Kyoto, Japan, December 19952, has given further impetus to enhancement. The Kyoto Declaration recognised four specific avenues for the enhancement of fisheries, i.e. stocking and restocking, assisting fishers to organise themselves, promoting community management schemes, and establishing user rights in open access. The Kyoto Action Plan also calls for the rapid transfer of know how in enhancement.

Recognising the high significance of the enhancement of fisheries for its member countries, the Inland Water Resources and Aquaculture Service of FAO, in close collaboration with the Department for International Development (DFID) of the United Kingdom has therefore organised an Expert Consultation on Inland Fisheries Enhancement that was hosted by the Government of Bangladesh. The major objective was to promote better understanding of how the various technical, socio-economic and cultural factors involved in implementing inland fisheries enhancement programmes must fit together to achieve success.

The Expert Consultation, held in Dhaka, Bangladesh, 7–11 April 1997 was attended by 42 participants from 13 countries. Technical papers from the meeting are produced as a separate supplement to this report.

1 FAO/Department for International Development of the United Kingdom. Report of the Expert Consultation on Inland Fishery Enhancements. Dhaka, Bangladesh, 7–11 April 1997. FAO Fisheries Report No. 559, Rome, FAO. 1997. 18p.
2 The Kyoto Declaration and Plan of Action. International Conference on Sustainable Contribution of Fisheries to Food Security, Kyoto, Japan, 4–9 December 1995. Organized by the Government of Japan in collaboration with the Food and Agriculture Organization of the United Nations. Published by Fisheries Agency, The Government of Japan. 22p.

The FAO Inland Water Resources and Aquaculture Service contributed by providing the technical secretariat for the planning and organisation of the meeting and sponsoring experts. The agenda of the meeting was jointly planned with the DFID. The DFID sponsored the attendance of some participants, provided the local organisation and covered the local costs for participants not associated with international organisations. Both organisations closely collaborated in the production and distribution of the report and its supplement.


Fishery enhancements

Culture-based fisheries, as defined in FAO Technical Guidelines for Responsible Fisheries3 (1997, FAO, Rome), are activities aimed at supplementing or sustaining the recruitment of one or more aquatic species and raising the total production or the production of selected elements of a fishery beyond a level which is sustainable through natural processes. In this sense culture-based fisheries are included in enhancement measures which may take the form of: introduction of new species; stocking natural and artificial water bodies; fertilisation; environmental engineering including habitat improvements and modification of water bodies; altering species composition including elimination of undesirable species, or constituting an artificial fauna of selected species; genetic modification of introduced species.

Inland fishery enhancement programmes are undertaken for a variety of social and economic reasons, including the desire to increase fishery production, to create employment, to alter the distribution of benefits, and to gain control of a resource.

Enhancement of fisheries resources is likely to be accompanied by social, economic, environmental and ecological changes. Steps have to be taken to ensure that such changes are contained within the boundaries of social, economic and environmentally acceptable risks as perceived by the society. These changes may lead to conflicts which would require resolution at all levels of society.

In Bangladesh, the host country of the present Expert Consultation, a National Workshop on Policy for Sustainable Inland Fisheries Management, held in Dhaka, March 1997, evaluated the lessons from fishery enhancement through community participation. Its conclusions and recommendations may serve as an example for approaching similar issues in some other countries4.

A number of measures are available for enhancing of production of inland water bodies ranging from simple stocking to full control of the fish population and the productivity of the water. The greater the control needed, the greater the human and ecological impacts are likely to be.

3 Aquaculture Development. FAO Technical Guidelines for Responsible Fisheries, No.5. Food and Agriculture Organization of the United Nations, Rome, 1997. 40p.

4 Anon. 1997. Recommendations. National Workshop on Policy for Sustainable Inland Fisheries Management. Organizaed by the Department of Fisheries and sponsored by the Ford Foundation and DANIDA. Dhaka, 22–24 March 1997. 18p.

For stock enhancement per se there must be a cost-effective means for mass production of young fish. On this criterion, very few developing countries are in a position yet to carry out effective stock enhancement without government or international assistance.

Better management of the fishery, habitat protection, physical rehabilitation of the ecosystem, and improvements such as establishment of fish sanctuaries, desilting canals and installation of fish passage facilities are interventions which should be fully explored and where appropriate implemented in conjunction with stock enhancement. Strategies should be formulated to test the different approaches.

Refugia and conservation areas for fish stock rehabilitation are proving beneficial to the maintenance of fish stock diversity and yields. A similar result is achieved where there exist traditional systems which recognise the need for maintaining equilibrium in the resource and its long-term sustainability. Governments should fully consider both approaches prior to the formulation of new fishery laws and regulations.

A significant increase in production from inland waters with associated benefits is possible through enhancement; however, water resources available for enhancements are not limitless nor is there a vast array of species whose performance is well known and predictable at individual sites. When constraints including climate, inputs, finances and institutions are considered, enhancements are unlikely to expand at more than a moderate rate.

Institutional constraints may equal or exceed technical constraints. Integration of the technical and institutional procedures of fishery enhancement programmes is essential to facilitate development.

The use of under-utilised indigenous and exotic species may be indicated where enhancements meet commercial and recreational demand. The potential impacts of the use of such species must be carefully assessed before enhancements take place.

Fisheries enhancements are technical interventions in existing aquatic resource systems, which can substantially alter the environmental, institutional and economic attributes of the system.

Approaches to the enhancement of fisheries should be led by the principles of participation and empowerment of all stakeholders; integration of technical, institutional, social and economic analysis; learning from management/development experience and adaptation of policies and procedures; accountability.

Intervention should be carried out following a process framework. A wide range of options, as well as alternatives to enhancements, should be considered. The expected benefits and costs of different options, and the uncertainties surrounding these, should be evaluated using interdisciplinary methods of analysis. Learning should be made an objective of the intervention, and options should be evaluated for their potential to yield information as well as technical, social, economic and environmental benefits. Outcomes of intervention should be monitored, and feedback provided for the improvement of policies and procedures.

Stocking relationships

Analysis of existing datasets demonstrates that strong correlations exist between stocking densities and yield, and between yield and area of water body stocked. These relationships indicate that stocking is a biologically viable practice for species that do not have strongly self-reproducing populations or where the carrying capacity of the water has not been reached. Supporting data show that rates of return under these conditions can be high enough to make enhancements economically viable.

Generalised statistical models vary in their data requirements and their accuracy and should be viewed with caution when applied to the management of individual sites. To be effective such models have to be derived from empirical experience on comparable sets of water bodies and be readily accessible and useable by a wide audience.


In general three kinds of models are required for strategic planning of enhancements. One is needed to predict fisheries potential under natural conditions. Another is needed to predict fishery potential under various kinds of enhancements to compare the benefits with those from unenhanced fisheries. The third is required to predict losses of potential yield due to general environmental degradation so that mitigation is properly scaled and financed.

Modelling is used in stock enhancement programmes for four main purposes:

to gain an understanding of the processes regulating the potential yield from water bodies;
to determine the relationships between fish yield and indicators of stocking inputs;
to provide input information for optimising the success of stocking programmes; and
to minimise possible adverse impacts.

Basic measures of physical, limnological and population characteristics are used to predict the potential yield from reservoirs, lakes and small water bodies. Similar models are available for rivers. Although large riverine systems have been stocked to attempt to raise productivity and to conserve anadromous species, models in these cases are less evolved.

Modelling must be recognised as a tool in formulating stocking programmes and managing fisheries but must be used in conjunction with evaluation of cultural and societal issues when assessing implementation risks and benefits. Although it is difficult, perhaps impossible, to establish a predictive model that would determine project success, models of risk assessment and decision-support models may contribute to the planning process and may reduce the chances of program failure.

Cage culture

Cage culture is expanding rapidly in parts of the world as an alternative or supplement to other forms of enhancement. There is also a strong trend towards the intensification of culture methods. The relatively high cost of this intensive form of culture leads to a change in orientation toward production of higher value products with good market opportunities. Supporting such systems through purchase of marketed food may compete with a demand for the same food by the poor segment of the human population. Nevertheless, cage culture remains a major tool for fish yield enhancement for a variety of water bodies and has further potential for the production of seed.

Information and monitoring

Globally, inadequate information for enhancements is a constraint. This ranges from poor quality and coverage problems in nationally aggregated data that are reported to FAO to the inadequate collection of location-specific information to evaluate the outcomes of enhancements. Fisheries production data alone are not sufficient to support enhancements. Social and economic data are also required to fully evaluate status and trends. Lack of comparability and compatibility among data sets and lack of clear definitions of fisheries activities is a problem. This has prevented a clear separation between the data from aquaculture and the data from inland capture fisheries. A fundamental impediment is that aquaculture is not recognised as a separate economic activity under the International Standard Industrial Definition of all Economic Activities (ISIC).

Data collection (reporting) efforts from national enhancement projects should recognise that resource limitations in many developing areas may constrain completion of data surveys/questionnaires. Therefore, governments and intergovernmental organisations should monitor practical indicators and should strive to streamline and simplify data collection and reporting. To maximise the use of limited resources national programmes should link to intergovernmental initiatives in monitoring enhancement programmes.

Short-term monitoring of project performance is not always beneficial as it does not clarify the various effects and interventions. Its extension beyond the life time of the project may be important. However, as monitoring is expensive, it needs to be followed by evaluation of the results and lessons learned on which to base future enhancement strategies. Geographical information systems (GIS) provide a powerful method to use models as decision support tools with relation to fisheries enhancement.


It is recognised that enhancement measures may lead to changes in ecosystem structure and processes. These issues should not be used as a mechanism for restricting development so long as the changes are acceptable to immediate stakeholders and society at large. Environmental impacts of enhancement activities may not be limited to the target water body but may extend throughout the watershed and into transboundary waters.

However, there is an important distinction between perceived and actual problems when examining environmental conditions. The paucity of knowledge of the existing environmental state of inland waters makes it difficult to assess fully the impacts of many current projects.

Wastes produced from more intensive cage operations may result in benefits by stimulating open water productivity and thus fish production, or by permitting the use of less intensive types of cage culture. Alternatively, intensive cage culture can cause adverse changes in water quality, leading to deleterious effects on fish production and amenity value. Impact and environmental capacity models require further development and validation.

Applied research, including documentation and syntheses of experience, on impacts and mitigating measures of inland fishery enhancements is urgently needed. In many areas, there may be a need to provide for environmental assessments on fishery enhancement activities, including aquaculture, which would help to identify potentially significant impacts and mechanisms for mitigation and rehabilitation. Environmental assessment procedures are usually conducted in a step-wise manner. For each fishery enhancement proposal it would be appropriate to undertake firstly only an Environmental Screening against a check list containing environmental and social criteria, (the criteria need to be developed), only then moving on to an Environmental Analysis, or Environmental Impact Assessment, if the initial screening identifies such a need.

Enhancement activities may change the disease status of aquatic organisms in ecosystems. The potential impact of disease on existing and introduced stocks resulting from enhancements should be carefully assessed, particularly in respect of the introduction of exotic species and strains. Assessment should be carried out according to internationally recognised codes of practice. A contingency plan for controlling and mitigating the impacts of ecologically significant disease outbreaks should be considered before enhancement occurs.

Genetic resource issues

The genetic and species diversity in wild aquatic populations should be conserved, protected, and utilised in the inland fishery enhancement and development. Management of genetic resources is important to the long-term success of enhancement projects and to the improvement in production and other traits of stocks used in enhancement.

Food security and socio-economic benefits might sometimes take priority over measures to exploit genetic knowledge. However, it should be recognised that reliance on genetically depauperate stocks for enhancements, or neglect of genetic diversity of wild stocks, may lead to declining yields.

A variety of techniques exist to characterise genetic variability and to improve stocks genetically. Where appropriate, genetic techniques should be used for monitoring dispersal of released fish and to check for introgression with wild populations. Progress in selective breeding for aquaculture suggests that similar principles could be applied to stocks for enhancement. However, efforts must be made to minimise risks to wild populations when improved strains are used.

The choice of any genetic management scheme or genetic improvement technique will depend on the objectives of the enhancement programme, which should be explicitly stated.

Farmed fish or fish used for stocking may interact with wild species directly or indirectly and thus affect the wild populations. The impact of this interaction is not well known and should be examined from ecological and genetic points of view.

The process of farming aquatic species may lead to a loss of genetic variation, especially rare genes, unless active hatchery management is undertaken. Domestication is a desirable outcome of many aquaculture breeding programmes, but may not be desired if, for example, the goal is conservation of wild stocks, or to produce a stock that performs well in a capture fishery.

Recommendations and guidelines on genetic resource management and utilisation can be, and have been, formulated, but following or implementing may be difficult due to inadequate resources or incomplete information. The release of non-reproducing animals (e.g., triploids) is a means to reduce the chance of hatchery x wild stock interaction, but such techniques may be difficult to apply on a practical basis for many species. However, an objective of many stocking programmes is the establishment of self-sustaining populations. The use of local species and populations in enhancement may also reduce adverse impacts from the interaction between hatchery and wild stocks.

It may be desirable to establish nucleus breeding centres, actively managed and supported by government or industry. These would provide appropriate broodstock to hatcheries producing fish for enhancement and should shoulder the responsibility for adhering to genetic and other appropriate guidelines (e.g., fish health). Broodstock numbers should be sufficiently high to minimise the loss of genetic variation through inbreeding.

Genetic resource management requires improved record or data keeping in hatcheries and in natural and enhanced populations. Data collection needs to be an ongoing exercise, the details of which will depend on the management objectives.

Efforts should be made to disseminate information and educate managers and stakeholders as to the principles and benefits of genetic resource management.

Social, economic and institutional aspects

Enhancement can increase the amount of economic surplus which can be generated from fisheries under efficient management. The maximisation of sustainable societal benefits should be the principal objective of enhancement.

Appropriate attention to social, economic and institutional aspects may contribute as much to the success of enhancements as can physical and biological factors.

Enhancements are more effective and sustainable where the resource users assume the responsibilities and costs of management. Governments, however, retain a role in initiating and implementing such schemes and in providing and enabling the legal, institutional and mediating framework for their continuation. The assignment of property rights and limitations of access are preconditions for sustainable enhancement of aquatic resources.

Financing enhancements depends on 1) government policies; 2) fishery property rights and access; and 3) level of community management/co-management. Communities with well-defined property rights are better able to pay for and manage enhancements.

NGOs can play an important part in promoting participation and in safeguarding equitable distribution of the resulting benefits. NGOs may also have an important catalytic role in the transition from government ownership to community based or private management. Their role in community based inland fisheries development has been emphasised by the National Workshop on Policy for Sustainable Inland Fisheries Management.5

Enhancements can stimulate changes in the rules, requiring an understanding of institutional dynamics. It is therefore important to understand the institutional arrangements at various levels, which affect people's behaviour and hence potential outcomes of enhancements.

The move towards community-based or private management of fisheries usually requires extended time scales since participatory approaches are implicit and take longer to implement.

Precautionary approach

The balance between increased fish production and the conservation of the environment may need to be achieved in the face of inadequate knowledge, uncertainty, and limited resources. Actions should be preceded by planning and risk assessment. Risk assessment should involve ecological, genetic and socio-economic factors.

Guidelines and codes of practice for responsible fisheries are excellent precautionary measures, but may be difficult to implement. Elements of the precautionary approach that may be applied to potential enhancement projects include, inter alia: i) identification of the potential adverse impacts; ii) establishment of the targets of the enhancement programme (i.e. goals) and limits to adverse impacts caused by enhancement; and iii) establishment of contingency plans once limits are approached. A pre-agreed plan of action should be implemented in the event that adverse impacts become unacceptable, although it should be recognised that many impacts may be irreversible.

5 Anon. 1997. op cit.

Fishery enhancement programmes are associated with various levels of risk. Conflict resolution is an important tool for recognising uncertainty and accepting risk in social, economic as well as technical issues.

Efforts to balance fisheries enhancement with the interests of other users of the water body and conservation require an integrated aquatic resource strategy to minimise conflict and risk.

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