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IV. BIO-TECHNICAL ASPECTS

by

B. Haight
Aquaculturist

1. INTRODUCTION

Years of aquaculture research and practice have produced a basic understanding of the biotechnical factors important to the successful cultivation of many fish species. However, experience has shown that despite this knowledge, efforts to implement small-scale aquaculture are often not successful. One hypothesis to explain this failure is that the biotechnical factors, although well understood, are influenced by eco-environmental, socio-economic, and socio-cultural factors particular to small-scale aquaculture. In analysing small-scale aquaculture systems from these points of view, it would be useful to characterize each system by its biotechnical factors, identify biotechnical constraints and suggest points of integration with eco-environmental, socio-economic, and sociocultural factors identified by others. The final result will suggest a practical methodology for integrating small-scale aquaculture successfully into rural agricultural development.

2. CHARACTERIZATION OF AQUACULTURE SYSTEMS

2.1 General Biotechnical Factors

A general set of biotechnical factors can be said to apply to any aquaculture system: land and water suitability; fish seed; consumable inputs (feed, fertilizer, treatment); management process; and output (fish, byproduct). Specific descriptions of these factors are particular to each aquaculture system and its setting.

2.2 Target Group

While small-scale aquaculture may be practised anywhere in the spectrum from rural-poor to urban-rich communities, it is primarily among rural-poor farmers that problems of implementation arise. Such farmers may be characterized as having: varying degrees of access to unimproved land and water; surplus of underutilized labour; fixed family social roles in regard to agriculture/fishing activities; scarce capital; low level of general education and knowledge of aquaculture techniques; high level of knowledge of local food crop systems and ability to innovate to meet changing local circumstances; motivation to act to minimize risk; and motivation to act to produce income. In particular, this paper will refer to target groups and aquaculture systems in the context of Southern Africa.

2.3 Production Methods

The degree of intensification of the aquaculture process is a useful way to characterize production methods with reference to biotechnical factors and target groups. Whereas technical innovation at any point in the aquaculture process can be used to overcome environmental constraints and increase the carrying capacity of a system, intensification relates more to economic growth and the application of greater resources to the aquaculture process. Since in this case the target group is at the low end of the economic scale and lacks access to many resources, the degree of intensification may be used to initially identify those production methods which are relevant to rural-poor farmers. General characteristics of production methods at three levels of intensification are given below.

2.3.1 Extensive

  1. Use of existing impoundments, or labour-intensive improvements to basic land and water resources to create ponds.

  2. Mono- or polyculture of unimproved species reproducing naturally in the production unit or stocked from outside sources.

  3. No or low consumable inputs, similar to levels in rural small-scale agriculture.

  4. Periodic management schedule similar to rural small-scale agriculture with scope for production improvements based on strategy and skill development.

  5. Low risk due to low investment of time and capital.

  6. Low yields (0.5–2 ha/year) from continuous or periodic harvesting sufficient for home consumption and possible minor income generation.

2.3.2 Semi-intensive

  1. Labour-intensive construction of ponds on otherwise unimproved land with some capital improvements relating to water control; no inconsistent with improved farming systems, especially irrigation, although lack of skilled labour and capital may limit the extent of improvements.

  2. Mono- or polyculture, or monosex culture, of selected fish species from a certified source; possible propagation of seed in the production unit after initial supply, otherwise restocking from a separate seed production system.

  3. Level and timing of consumable inputs essential to system performance and similar to improved small-scale agriculture practices requiring fertilization and animal husbandry requiring feeding; inputs may be gathered on-farm, or purchased with operating capital.

  4. Daily management requiring semi-skilled labour similar to that in agriculture and animal husbandry with special skill development for fish harvesting.

  5. Increased risk due to higher inputs and sensitivity of system.

  6. Medium yields (2–5 ha/year) and periodic harvest of crop favouring local marketing with scope for high income production; system may still be cropped continuously for home consumption.

2.3.3 Intensive

  1. Labour- or capital-intensive construction of ponds or other water-holding systems requiring major capital improvements relating to water and fish control.

  2. Mono-or polyculture, or monosex culture, of selected species at high density from a certified source; propagation of seed in a separate highly technical system.

  3. Level and timing of consumable inputs highly intensive, produced using equipment on-farm from purchased inputs or procured ready-made.

  4. Continuous management by trained personnel.

  5. High risk consistent with sophisticated level of inputs and high density system.

  6. High yields (5–10 ha/year) require well-developed marketing and transport system for large amounts of fish harvested continuously or periodically.

From the description of aquaculture production methods in relation to their economic and resource level, it can be hypothesized that extensive and, to some extent, semi-intensive production methods are more appropriate to the rural-poor farmer. A more detailed biotechnical description of specific aquaculture systems which use these methods can help to identify the constraints inherent to each system and provide a path for more effective integration of aquaculture into rural farming in Southern Africa.

2.4 Small-Scale Rural Aquaculture Systems

Within extensive and semi-intensive production methods, there are four aquaculture systems which can be proposed for the rural farmer:

  1. Extensive system: stocking/fishing of reservoirs;

  2. Extensive system: stocking/fertilization/harvesting of ponds;

  3. Semi-intensive system: stocking/fertilization/feeding harvesting of ponds;

  4. Semi-intensive system: stocking/fertilization/feeding/harvesting of ponds in association with animals.

The biotechnical details of these systems and examples of their implementation are given in an appendix to this paper.

3. ANALYSIS OF BIOTECHNICAL FACTORS

Having set out the biotechnical details of the aquaculture systems appropriate to rural small-scale aquaculture development in Southern Africa, it would be useful to see how these factors are interrelated and which are most limiting. Such analysis will suggest the biotechnical issues which will be most important to consider when assisting communities to plan aquaculture development.

3.1 Interrelated Factors and Limits

3.1.1 Site (size, form, soil quality of land; volume, quality of water)

Each system has specific minimum site requirements which must be met, but amounts beyond the minimum of a given system do not improve the performance of the system so much as the obsolute production result.

3.1.2 Organism (fish and animal species)

Each system requires fish with particular breeding, feeding, and growth habits in minimum quantities at specific times. The quantity and size of seed fish available together with the size of the unit will determine productivity potential in relation to stocking density and input levels, up to the carrying capacity of the system. Systems can overcome eco-environmental limitations using locally adapted species of otherwise similar habits. Production may vary among different species and mixes of species which otherwise fit the system. Adding animals in association with fish will increase overall productivity of the system, but they will only improve the aquaculture system's productivity if they provide it with an additional consumable input not already available.

3.1.3 Consumable inputs (fertilizer and feed)

Animals require a basic metabolic energy input to survive and an enhanced energy input to grow. The quality and quantity of fertilizer and feed determine the energy input. Increased energy input per animal will increase growth rate only up to the energetic limit of a particular species. Increased density requires increased absolute consumable energy inputs into the system to maintain per animal ration. The feeding and digestion habits of fish and associated animals directly influence the growth effects of feeds. Water quality affects the ability of fertilizer to produce aquatic plant and animal growth.

3.1.4 Treatment (labour, capital, management)

Deficient or untimely labour and capital input may cause the system to malfunction due to site preparation deficiencies, lack of consumable inputs, or poor management. Each system has a minimum level of management, which if improved and combined with increased inputs and/or improved organisms can increase production towards carrying capacity.

3.2 Issues for Community Development

When considering the interrelationships and limits of biotechnical factors within the context of promoting small-scale aquaculture in poor rural agricultural communities of Southern Africa, certain issues arise, crucial to the success of the rural aquaculture system.

3.2.1 The availability of suitable land and water for aquaculture will, in the first instance, determine whether an interested community can even consider developing aquaculture. Thereafter the suitability of land in terms of form, size, and soil quality, will determine the range of aquaculture systems a community may choose from.

3.2.2 The availability of suitable fish in terms of species choice, size, and source will determine whether an interested community with a usable site can effectively proceed with aquaculture. Fish suitability will narrow the range of systems that can be developed.

3.2.3 The availability of consumable inputs will further limit the range of systems and also the intensity of the system and the level of production results.

3.2.4 Labour and capital inputs will limit the scale and intensity of the system.

3.2.5 Management capability will limit the intensity but can be improved through training and experience.

4. INTEGRATION INTO RURAL AGRICULTURAL DEVELOPMENT

4.1 Relation to Agriculture

Throughout this paper aquaculture has been examined more in the context of agricultural activities than of fishing activities. In the Southern African region, it is likely that most communities considering aquaculture will be made up of farmers. To assist them in the development process, some useful relationships between aquaculture and agriculture systems can be described.

4.2 Relation to Eco-environmental, Socio-economic, and Socio-cultural Factors

This paper outlines the biotechnical factors found in aquaculture systems, and the issues they raise for community aquaculture development, as a basis from which a community may choose appropriate aquaculture systems. How a community makes this decision is crucial to the success of the aquaculture venture. In the past the system selection has been made primarily on the biotechnical issues, ignoring to a great extent the other factors important to community development. The results have been less than successful efforts to implement aquaculture systems which are sound technically but which fail to meet the eco-environmental, socio-economic, and sociocultural requirements of the rural farming community. The biotechnical issues identified here should be carefully interrelated with community development issues formulated for the other factors to provide a set of aquaculture system options which take into account all the needs of the rural farming community.

4.3 Participatory Planning

An important aspect of integrating aquaculture into rural development is the role played by rural farmers in the planning process. For the greatest effectiveness, in terms of farmer interest and knowledge of local conditions, rural farmers should initiate and have control over the planning process. Promotion of aquaculture involves not simply the removal of constraints but also the active interest of participants. While many farmers may want to produce, eat, and sell fish, it will require guidance by change agents to ensure that farmers understand and consider the limiting factors when making their decisions. If farmers have poor understanding of aquaculture techniques to begin with, then it will be important to emphasize the role of bio-technical factors, since other factors, especially socio-economic and sociocultural, may be better represented in farmer decision-making. This task may be made easier for change agents and more effective for farmers by closely relating biotechnical issues to the local farming system. This method will also promote the practical integration of the selected aquaculture system into the local farming system.

4.4 Monitoring

Planning, implementation, and evaluation exercises will require monitoring of aquaculture activities by farmers and change agents. The information gathered should be used at each stage to guide decision-making regarding the resolution of biotechnical issues.

4.4.1 Planning

  1. Inventory of resources relative to aquaculture:

  2. Does the aquaculture system finally chosen match the resources available to the community?

  3. Review of aquaculture development plan for technical feasibility.

4.4.2 Implementation

  1. On-site technical review of site selection, pond construction.

  2. Production cycle:

4.4.3 Evaluation

  1. How do the actual planning and implementation activities compare with the plan of operation?

  2. How does the actual result compare with the expected result?

  3. Are certain biotechnical issues more difficult to resolve?

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