Coastal Aquaculture and Mariculture (2+1)

Unit 3 - Methods of coastal aquaculture and mariculture

3.1.1. Site Selection

• Selection of right site is probably the most important factor determining the feasibility of viable operations. Many farms laid out on poor sites have been abandoned after considerable investment of money and effort leading to heavy losses. However, ideal sites may not be always available and some compromises may need to be made.
• Selection of site is generally based on species to be cultured and technology to be adopted. However, some factors are common to all sites such as, agro-climatic conditions, access to hatcheries/ seed centres, roads and communication, access to markets, protection from natural disasters, availability of skilled and unskilled labour, public utilities etc.
• All available meteorological and hydrological information needs to be collected. Soil characteristics, quality and quantity of available water, ease of filling and drainage, especially by gravity, are basic considerations.
• Land elevation and flood levels have to be ascertained. The maximum flood level in the last 10 years and the highest astronomical tide should not be higher than the normal height of the dikes. It will be advantageous to select land with slopes not steeper than 2 percent. The area should be sufficiently extensive to allow future expansion and preferably be of regular shape to facilitate farm design and construction.
• Among other important general factors be considered are the existing and future source of pollution, developmental plans for the neighborhood areas and legal and social aspects of farm establishment. The possible effects of the discharges of the farm on the environment needs to be considered. This can greatly influence the attitudes of the local communities to the proposed farming and hence their future cooperation.
• Sites generally available for the coastal pond farms are tidal and inter-tidal mud flats in protected areas of near estuaries, bays, creeks, lagoons and salt marshes. If the ponds need to be supplied water through tidal flow and information on tidal amplitude at the site is essential.
• Data on high tides and low tides need to be collected from tide charts available of the nearest port. The elevation of the land relative to the tides is important to decide on the type of ponds to be constructed (whether tidal fed or pump fed) and amount of excavation necessary for constructing the ponds.
• The construction of ponds in areas reached only by the high spring tides would require excavation, leading to high cost of construction. For tidal fed ponds sites with elevation of between 0 and 140 cm relative to tides is necessary. However, if tidal energy can be replaced with other forms of energy the above limitation would not apply.