The feasibility of achieving the required production will naturally depend on a number of factors including natural, technical and human resources, legal and environmental conditions and funding and financing arrangements. Land, water and climatic conditions are probably the most important natural resources to be assessed. Though detailed site surveys cannot generally be done in the overall planning stage, identification and mapping of potential areas have to be attempted. Among land areas, priority will naturally be given to those that are presently not productively used, as for example in agriculture. However, in some areas where economic agriculture is not possible due to soil or other conditions, even agricultural land may provide suitable sites for pond farms. In the assessment of sites for aquaculture, careful consideration has to be given to possible environmental impacts. There is often a tendency to describe all lands not directly used by man as potential sites for aquaculture, and estimate production potential of the country based on total areas of such lands, as for example coastal swamps.
Many of the coastal swamps are under man-groves, the ecological importance of which has received special attention in recent years. Dense mangroves along the margins of estuaries, lagoons and bays prevent soil erosion and aid silt accretion (fig. 3.1). The marginal zones that are inundated regularly by tides contribute substantially to the productivity of the waters and form the nursery grounds of many marine and some inland species of fish and shellfish. Conversion of such areas into fish ponds is likely to affect the capture fishery resources and adversely affect the environment. In fact, such areas should not be considered for pond farms, for other than ecological reasons. In the first place, it would be too expensive and difficult to clear the tall mangroves that grow along the margins and the dense growths behind them. In addition, pond farms built along these marginal zones will be more exposed to natural disasters like high tidal storms, typhoons and cyclones. On the other hand, the back mangroves, characterized by less dense and bushy growths and only occasional tidal inundation, contribute little to aquatic productivity and are more easily cleared and converted into pond farms (fig. 3.2), so only these areas should be considered when assessing available land for aqua culture. Similarly, when considering coastal waters, other uses of such areas should be taken into account such as for navigation or recreation, besides possible problems of environmental management, including water quality control and waste disposal.
For land-based aquaculture, the availability of adequate quantities of water of appropriate quality is an obvious requirement. Natural bodies of water, man-made irrigation or multi-purpose systems and ground water are major resources to be assessed, besides rainfall which is not always a reliable direct source of supply. The quantity of water required will depend on the type of culture system to be adopted as, for example, stagnant ponds, flow-through systems, cages or pens, etc. Though technologies for recirculation of water exist, large-scale use of it other than for hatcheries seems too expensive at present. As well as the source of water, the means of supplying it to the aquaculture facilities is also important, because of the costs and availability of energy for pumping.
Assessment of suitable areas for development will lead to the determination of the systems of culture or species of animals or plants that can be cultured. Although many cultured species are gradually being acclimatized to grow in different temperatures and salinity ranges, there are still tolerance limits and ranges within which they will grow fast or reproduce. So, agro-climatic conditions are a determinant in species selection. As mentioned earlier, consumer preference and acceptance will also have to be considered.
It is understandable that the economic viability of a development plan should be judged by the investments’ ability to achieve reasonable returns, if private sector investments are to be promoted. Unfortunately the environmental cost, which is especially important, has been neglected and this has brought considerable disrepute to the sectors, with many people questioning the sustainability of all types of aquaculture. The Bruntland Commission (the World Commission on Environment andDevelopment) in its report Our CommonFuture, defines sustainable development asdevelopment that meets the needs of the present without compromising the ability of future generations to meet their own needs. Adherence to the principle of sustainable development also involves balancing between intragenerational equity and needs for environmental protection as well as development. In view of the present low state of knowledge and experience, the necessity of a precautionary approach is accepted. Development may require large amounts of financial and environmental risks, which cannot always be fully assessed with any certainty. The principle of ‘polluter pays’ for the cost of environmental damage as well as its monitoring and rectification is the basis of environmental management. Therefore some form of environmental assessment will be required as part of the planning processes. The wide range of agencies involved in decision-making on an aquaculture project, and the wide variety of stakeholderswith differing criteria, make decisions on the application of a precautionary approach policy in planning of aquaculture development extremely complex. The need for intergenerational equity makes it more difficult to evaluate the development project. Aquaculture, like all other development activities, may change the balance of natural resources and their distribution. These changes have to assessed to ensure that vital components are sustained or increased in the longer term.
Planning on a short-term or a long-term basis would require evaluation of the costs and benefits of aquaculture and how it fits into the total priorities of economical development of a country in the allocation of natural resources. The aquaculture sector is a relatively new innovation in many countries, there are many other conflicting uses for natural resources. Planning aquaculture development as a priority activity on a national basis would require comparison of the costs and benefits of aquaculture not only economically but also environmentally. Estimation of environmental capacity to accommodate additional resource use without any negative influence on the environment has to be determined in the location where aquaculture is to be carried out. Environmental capacity measures the resilience of the natural environment to the impact of additional activities planned to be carried out. In the case of aquaculture, the rates at which nutrients and organic matter are discharged from an aquaculture farm can trigger eutrophication, and the resultant lowering of dissolved oxygen level that can be tolerated without causing mortality of the indigenous biota.
It would be possible to map out the areas that can be utilized for aquaculture, without adversely affecting other legitimate uses of natural resources. The assessment could be expected to yield the basis for delineating aquaculture zones that can be allocated for the aquatic farming industry while avoiding unhealthy competition for land and water resources. If the licensing of aquaculture farms is adopted, it could be extremely helpful to recommend what systems and species might be suitable for the area underdevelopment. While water is an important natural resource for aquaculture, it has to be recognized that in the future water resources may become scarce and water shortages may occur in many areas. This is an important constraint that must be taken into account, and appropriate systems and species may have to be considered for farming under special circumstances. Diverse farming systems are presently available and may be perfected in the future, such as cage and pen culture in inshore and off-shore locations, flow-through systems in tanks and raceways, recycling and recirculating open ponds, or indoor systems including the commercial production of tropical species in treated water recirculating systems.
When planning aquaculture one should consider also the potentialities for enhancing aquatic stocks that may have been affected by unfavourable conditions in the area under development and the building up of culture-based fisheries where suitable conditions exist. Stock enhancement may include building or promoting culture-based fisheries by the release of healthy seedlings, habitat improvement, fertilization, the introduction of food organisms and the reduction of predatory or competing organisms. Transplantation and stocking of several anadromous species of commercial importance have been successfully undertaken in the US, Canada, the former USSR and, lately, Iran. Pacific salmon (Oncorhyncus spp.) and Caspian sturgeons (Acipenser spp. and Huso spp.) and Salmo spp. are well-known species that have regularly been stocked to enhance the overfished or diminished populations.
Social implications of development planning become dominant when sustainability is a major consideration. The need for the involvement and cooperation of local communities in planning an aquaculture project to ensure its successful operation are often emphasized. Since a broad range of agencies have a decision-making role in an aquaculture project, all possible ways of integration and coordination with local representatives of the agencies concerned have to be considered. Stakeholders in the relevant sectors have to be consulted and their views reflected in the plan .