|AFRICAN REGIONAL AQUACULTURE CENTRE, PORT HARCOURT, NIGERIA|
|CENTRE REGIONAL AFRICAIN D'AQUACULTURE, PORT HARCOURT, NIGERIA|
- TECHNICAL AND NON-TECHNICAL CONSIDERATIONS IN SITE SELECTION
M. N. KUTTY
African Regional Aquaculture Centre
Port Harcourt, Nigeria
Lectures presented at ARAC for the Senior Aquaculturists course
UNITED NATIONS DEVELOPMENT PROGRAMME
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
NIGERIAN INSTITUTE FOR OCEANOGRAPHY AND MARINE RESEARCH
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I N T R O D U C T I O N
2. SITES SUITED FOR AQUACULTURE AND CULTURES TYPES
3. CULTURE TYPES (SYSTEMS)
TECHNICAL AND NON-TECHNICAL
CONSIDERATIONS IN SITE SELECTION
2. MAIN ENVIRONMENTAL FACTORS
3. SOCIO-ECONOMIC CONSIDERATIONS
4. POLITICAL AND LEGAL CONSIDERATIONS
5. CLIMATIC AND OTHER MAIN ENVIRONMENTAL FACTORS
Success or failure of any aquaculture venture largely depends on the right selection of the site for it. In choosing a site several factors other than the physical aspect of the site are to be considered. These factors along with the various types of culture sites and systems, are shown in a generalized form in Fig. 1.1 The factors to be considered cut through various disciplines and range from socio-economic aspects of aquaculture to all the physico-chemical and biological conditions of the environment; this consideration should be with reference to the specific culture system and species chosen (see “Species selection for aquaculture” in this manual series) as viewed from the objective of the venture. The objectives of aquaculture could be to produce whole-some nutritious food for local consumption. Through small scale rural farms or large vertically-integrated commercial systems. Alternately the objective could be for the production of high-cost fish or shrimps for exports and earning foreign exchange for the countries concerned. Those are elaborated elsewhere in this manual series.
As it would be obvious, no venture can sustain unless it is profitable. Site selection is the process by which various factors indicated are considered to enable one to decide on the right site for a specific culture system or alternately, to decide on a culture system suiting the site available.
Under the present subject of Site Selection, we shall be looking at the sites suited for aquaculture, different culture types, very briefly to begin with and then deal with the various technical and non-technical aspects of site selection in some detail.
Several types of water bodies can be used for fish culture - the choice of a specific body would depend on the objective of the investors and also the type of aquaculture.
Among the sites suitable for aquaculture could be listed: land-swamps, rivers, stream beds; coastal areas - bays, estuaries backwaters, lagoons, salt marshes and mangrove swamps; lakes, reservoirs and other water bodies, including irrigation tanks and canals (Fig. 1.1, A & B).
The specific site to be chosen would be based on the requirement of the culture systems. Static water ponds are the most common, hence pond culture the most important system. Most of these are confined to freshwater areas, but brackishwater ponds are also becoming more common. There is a variety of culture systems which can be developed in open waters - the stocking and management of open waters themselves being major occupation, e.g. extensive stocking of man-made reservoirs and lakes. In the larger freshwater bodies and coastal areas cage and pen culture can be developed. Site selection for these culture systems has to be carefully done, based on the requirements of the species to be cultured and the structures to be erected for the culture. Here and in the culture systems where closed systems are used, the inputs required can be costly and management intensive. Thus there can be gradation of culture, systems based on the input costs and management strategy employed, from extensive, through semi-intensive to intensive.
The different culture systems in vogue are listed below:
static water ponds, running water culture, culture in recirculation systems (closed or reconditioned water);
culture in rice fields and integrated culture systems, as the duck-cum-fish and pig-cum-fish culture - or any fish-livestock-crop combination;
culture in raceways, cages, pens and enclosures; also
mollusc/oyster culture - hanging, on-bottom and stick methods (Fig. 1.1)
As mentioned already the choice of site for a specific culture system, would depend on the characteristics of the site and the requirement of the culture system - the latter again has two components, the species requirements and the structural requirements of the culture system.
Fig. 1.1.A FACTORS AFFECTING SITE SELECTION IN AQUACULTURE
Fig. 1.1.B FACTORS AFFECTING SITE SELECTION IN AQUACULTURE
There are several aspects to be considered for the selection of site for a culture system, as would be evident by a scrutiny of the various factors which go into these considerations
The various aspects will be discussed in sequence, during discussion under this subject. Both technical and non-technical aspects will have to be considered, which are:
Socio-economic, political and legal factors
Climatic factors and
Major environmental factors.
Under the last category various aspects, such as, topography and ground elevation; soil; water supply, and dynamics, physical, chemical and biological features of water, land-vegetation etc will have to be considered.
It will become obvious that while a culture system may be technically feasible, it need not be the right one because of other considerations, which are socio-economic. While only a brief discussion on this aspect will be included under “Site Selection for Aquaculture”, much of these will be discussed under separate subject heads (viz. Socio-economic aspects of aquaculture, Aquaculture Planning). Each culture type or system will also be discussed under separate subjects within this course.
In each case the fish (Sensu lato) species is considered with reference to the specific structural set-up, and it will be the objective of the culturist to manipulate the species and the environment to obtain an optimum (if not maximum) yield, considering the biological aspects and economics.
Culture systems, such as large water bodies or even small static water ponds, where fish are grown based on the natural productivity of the water bodies alone, can be the simplest. Increase in the productivity of those ter waters with the addition of fertilizers and artificial feeds would increase the complexity as well as fish production for unit of water area or more precisely water volume. But, as will be made out in later discussions, there is a limit for this increase in fish production under the set of conditions. These limits are set by the prevailing environmental conditions. Most of the complex culture systems are often attempts to overcome these limits, or changes made for culturing required species, not necessarily at the ‘peak’ productivity level, due to other reasons referred to.
The static water bodies have built-in limits due to the finite volume of water and deteriorations of water quality with increase in biomass per unit volume of water. Water quality improvement can be effected by incorporation of costly aeration or by changing the water; the latter leading to running water culture systems or culture in recirculating and closed water systems. Again use of natural running or moving water in water bodies for intensive culture (high biomass per unit volume of water) is done in pen and cage culture.
How do the fish and environment intrest in each of these culture systems? What are the advantages and disadvantages of each culture system? What should be the consideration of the site and the species (species selection) in each case? We will discuss these in detail when each culture system is taken up, in the present course.
As stated before, the choice of site and species (“Selection of species for aquaculture”) and a specific culture system should not be on technical considerations alone, but should be on total considerations of technical and non-technical aspects, the latter concerning socio-economic, legal and political factors.
TECHNICAL AND NON-TECHNICAL CONSIDERATIONS
IN SITE SELECTION
In selecting a site for a specific system of culture both technical and non-technical aspects need prime consideration. As already indicated a site could be suited ideally for farm fish production from a technical point of view alone, but on a review of socio-economic, political or legal aspect the project can be rejected. The selection of a site and success of a project is much dependent on considerations which are non-technical - such as acceptability of the fish produced (consumer preference), marketing facilities, labour available etc, or certain political or legal considerations.
The broad headings under which the technical and non-technical considerations for site selection are discussed, are as shown under:-
Socio-economic, political and legal factors
Main environmental factors.
The environmental factors can be further subdivided, for discussion:
Topography and ground elevations
Water supply, quantity and dynamics
Physical and chemical features of Water
Fouling/availability of spat (for mollusc culture)
Type and density of vegetation
As already pointed out these will be discussed in detail under “Socio-economic aspects of aquaculture” a separate subject in this course. We shall, however, refer to certain relevant points which should be considered for the selection of site.
They are socio-economic aspects such as social and religious customs'; consumer preference ; nature of manpower (labour) - quality and quantity - available; transportation and communication facilities; i.e. infrastructure facilities; accessibility and nearness to market; and also costs and availability of construction materials.
At this point it must be made out that the objectives of producing fish in a culture system should be clearly spelt out (see “Introduction to aquaculture” and separate discussion on “Criteria for selection of species for aquaculture”.) While the acceptance or preference of the local community would be of prime interest in producing fish for local consumption, the acceptability of the target group to whom the fish are supplied, in some cases, even by export, is of major interest. But consideration of other socio-economic aspects such as infrastructure facilities for post-harvest treatment of product including marketing, manpower quality and quantity, could be same, if the fish produced is for local (same province/country) consumption or export outside the country. Similarly relative merits or demerits of the specific site, with reference to availability and cost of materials and equipment for farm construction and subsequent needs for renewals in the farm structures and also for the maintenance of the farm, e.g. supplies of feed stuffs and fertilizers, should also be considered.
The aquaculture project execution should be a part of the overall planning for the specific area under the national plan for development, so that the project can fit into the country's or provincial plan for development of industry and agriculture. This is specially needed when aquaculture is a part of rural development programme, as indeed most such projects are. This should specially help in sharing infrastructural facilities of transportation (road), power supply and communications and also in judicious sharing of imports and recycling outputs. The advantages of their consideration in siting a project are obvious. We shall look into these aspects of macro-economic planning subsequently when “socio-economic aspects” and “aquaculture planning” are discussed in detail. Legal aspects, such as security of tenure, maritime laws controlling coastal waters (in cases where sites are coastal), legal size limits with reference to the ponds/culture area, as well as the species under culture, and closed reasons, should also to be considered. Several countries already have certain regulations concerning these legal aspects, some of which are in force, much before aquaculture was thought of as an industry.
In many cases these legal clauses cannot be easily modified, eventhough some attempt in this direction would be necessary, especially with reference to size-limits of fish and closed seasons. The latter regulations have been included to protect the species' survival under intensive capture systems of wild stock. While this protection may be necessary for such a case, here in aquaculture, capture from the wild fish of certain size, when the season for capture is closed legally, is only for protection of the fish by way of transferring the fish to culture ponds - either as brood fish or as fry or fingerlings in grow-out ponds. In some cases maritime areas through which navigational routes and certain other country priorities exist. These aspects should be considered in choosing the site for the aquaculture ventures planned.
I refer again to Fig.2.1 where all factors involved in site-selections are put together, and their influence on the culture sites and systems indicated:
The sub-topics, climate, topography and ground elevation, soil, water supply, physical and chemical features of water, productivity, vegetation - aquatic weeds etc, will be discussed separately in detail, under the subject of site selection for aquaculture.
It will be realized that much of these discussions involve several basic aspects of ecology and we have attempted to provide information of value in selection of site, at this level.
“Topography and ground elevation”, would lead to the construction of pond farms (a subject covered in detail, separately in the present course) and several aspects of environment discussed, have corresponding sections in “Selection of Species for Aquaculture” (also forming separate subject in the present course), for an environmental factor can be discussed only with reference to the effects it can have on the species. As we already pointed out, site environmental requirements for a culture system are the requirements of the species to be cultured.