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II. Selection of sites for aquaculture

1. Sites suited for different types of aquaculture

Land including swamplands; river and stream beds; coastal areas including bays, estuaries, backwaters, lagoons, salt marshes and mangrove swamps; lakes, reservoirs and irrigation tanks; other existing water bodies.

2. Technical and non-technical considerations in site selection

2.1 Socio-economic, political and legal factors

Quantity and quality of available manpower; social and religious customs; consumer habits; availability and cost of construction materials and equipment; transportation and communication facilities; security of tenure; maritime laws relating to the control of foreshore and sea bed in coastal waters; legal size limits; closed seasons, etc.; industrial and agricultural planning in the area; accessibility; nearness to markets.

2.2 Climatic factors

Temperature, sunshine, rainfall, evapo-transpiration, floods, hurricanes, winds and relative humidity.

2.3 Main environmental factors

(a) Topography and ground elevation: topography of land suitable for aquaculture; low-lying deltaic, coastal and hilly areas with suitable slope to facilitate water supply, drainage and low cost of construction; importance of ground elevation in relation to tidal ranges for locating coastal pond farms; ground elevations suitable for marine farms at different tidal ranges; topography of sea bed sites suitable for sub-littoral enclosures and sea bed cages; stability of shore and banks.

(b) Soil: importance of soil quality in construction of fish farm installations and productivity of overlying waters; the formation and classification of soils; soils suitable or capable of being made suitable for aquaculture; unsuitable soils; soil profiles; methods of studying soil profiles; physical properties of soil (texture, structure, colour, specific gravity, volume, consistency, pore space, etc.,); colloidal properties of soil; soil water; soil-water interface; movement of water in soil; percolation and drainage; inorganic constituents of soil (N, P, K); humus; soil reaction - saline, alkaline and acid soils and methods of correcting their characteristics; soil fertility and factors affecting it; fertilizer requirements for soil improvement; soil conservation.

(c) Water supply, quality and dynamics: main sources of water for aquaculture - ground water, water table and aquafers, rain water, extent and nature of watershed area, irrigation water, water from natural and artificial water bodies; multiple uses of water and aquaculture; assessment of available water supply for inland farms, quantification of water requirements for different types of aquaculture based on sources of supply, inflow, loss due to evaporation and seepage and renewal needs.

(d) Physical features of water: temperature, turbidity, colour, water movements, water conditions and depth; stratification of water; tidal amplitude and its seasonal changes in coastal sites and their bearing on farm elevation and water supply; storm surges, wave action and water currents and their effect on marine aquaculture installations; chemical features of water: pH, dissolved oxygen, acidity, alkalinity, total hardness, nitrogen, phosphates, silicates, salinity, chlorides, chlorine, hydrogen sulphide, free carbon dioxide, sodium, magnesium, potassium, calcium, iron, arsenic, biological oxygen demand and chemical oxygen demand; physico-chemical factors of special importance in aquaculture and their optimum ranges; possible ways of controlling principal factors, such as turbidity, temperature, pH, dissolved oxygen, alkalinity and salinity. Pollution of fishery waters by sewage, pesticides, industrial effluents and possible pollutants from intensive aquaculture; effects of pollution on fishes, shellfish and fish food organisms; physical, chemical and bioassay of polluted waters, waste waters, sludges and bottom sediments; pollution prevention and abatement measures.

(e) Productivity: concepts of aquatic productivity; primary productivity and its relation to fish/shellfish production in aquaculture; methods of measurement of productivity (oxygen method and Cl4 method). Phyto-biota (bacteria, planktonic and periphytic microscopic algae, macroscopic algae, and submerged, floating and emergent macrovegetation) and zoo-biota (periphytic, benthic, planktonic and other free-swimming animals); important groups of phyto-biota and zoo-biota and their value as fish/shellfish food; inter-relationships of phyto- and zoo-biota; methods of plankton, periphyton and benthos collection and analysis; importance of biota in the biological productivity of water bodies; effect of water quality on productivity; food cycle in water bodies.

(f) Fouling: intensity of fouling and its seasonal fluctuations; effects of fouling on marine aquaculture installations; preventive measures.

(g) Availability of spat: spat availability and its role in deciding on mollusc culture.

(h) Type and density of vegetation: quantitative and qualitative appraisal of vegetation; size and root system; cost of clearance.

Practicals

Collection and study of soil profiles; collection and identification of different types of soil; analysis of soil samples for determining their physico-chemical characteristics (texture, pH, conductivity, organic carbon, available nitrogen, available phosphorus and available potassium); survey of different types of sites; contour mapping.

Collection of water samples, waste waters, sludges and bottom sediments and their analysis for essential physico-chemical parameters, calculation of water supply requirements for selected aquaculture systems; pollution control in aquaculture waters.

Determination of primary productivity of selected aquaculture areas; collection and analysis of plankton, benthos, periphyton and nekton.


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