Site Selection

Selection for a suitable site is a critical activity and must be carefully determined before establishing of a shrimp farm. Site evaluation is not only undertaken to determine if a site is suitable for shrimp farming. It is also valuable in determining what modifications are needed concerning layout, engineering, and management practices to make shrimp farming possible at a given site. No site will have all the desirable characteristics, so a number of judgements have to be made for every site.

There are several factors involved during site selection.

Topography and Climatic Condition

Topographically, the best areas for shrimp culture are those with average natural ground elevations of about 1-3 m above mean sea level or at least 1 m above the highest high tide level to allow drainage and harvesting. The cost of pumping increases in highly elevated sites. The sites should have minimum vegetative cover, be near the sea or other natural waterways such as rivers and streams, have easy access to roads, a sparse population and be nearly square or rectangular in shape.

In terms of climatic conditions, areas having short and not as pronounced a dry season with moderate rainfall distributed throughout the year are the best suited for shrimp farming. A pronounced long dry season may cause an increase in water temperature and salinity, which will promote excessive growth of algae and result in oxygen depletion at night.

Infrastructure

Accessibility

The farm must have good accessibility either by road or water, and communication systems throughout the year in order to facilitate supervision and transport of materials and products. It is important that the farm be within 3-6 hrs traveling time from the hatchery to avoid excessively long transportation time of the larvae and should be within 10 hrs from the processing plant to avoid deterioration of the product.

Electricity

Availability of relatively cheap and reliable power source is a major consideration in site selection. In areas where electricity supply exists, it is practical and beneficial to utilize electric power to run the farm, especially for the intensive culture system. It is advisable to have a back-up electricity generator as a secondary power source.

Security

Areas free from security risks result in favorable working conditions, productivity and less extra costs.

Availability of Labor and Other Factors

The availability of labor, equipment and commercial feed and supplies ensure smooth operations and successful crop.

Water Supply

Site should have good pollution free water supply of both freshwater and brackish water. Water quality parameters required for maximum feed efficiency and maximum growth of Penaeus monodon are given below:

Water Parameters	Optimum level
Dissolved Oxygen	3.5-4 ppm
Salinity	10-25 ppt
Water Temperature	26-32 (°C)
pH	6.8-8.7
Total nitrite nitrogen	1.0 ppm
Total ammonia (less than)	1.0 ppm
Biological Oxygen Demand (BOD)	10 ppm
Chemical Oxygen Demand (COD)	70 ppm
Transparency	35 cm
Carbon dioxide (less than)	10 ppm
Sulphide (less than)	0.003 ppm

Water from polluted areas containing high concentrations of suspended solids and organic wastes such as effluent water from industry; urban areas, agricultural and other farm locales should be avoided. A settling pond or a large reservoir should be used in such areas for sedimentation and treatment. In saline areas, a source of freshwater is useful for adjusting the salinity in the ponds and for domestic use by farm staff. The freshwater should be good enough for use and adequate throughout the year.

Soil Conditions

The type of soil is the most critical in site selection, since the shrimp will spend most of their time on the pond bottom during the culture period. Usually, clay or loam-based soil containing more than 90% clay and pH between 6.5-8.5 is preferable. Sites with sandy or silty soil should be avoided due to their porous nature that may lead to erosion, seepage of water and easy infiltration of waste into the soil. Prior to construction of ponds, samples of soil should be taken randomly from 5-10 spots at the surface and at 1 meter deep and sent to a laboratory for the analysis of soil texture and pH. Such data will be useful during pond construction and preparation.

Mangrove or acid sulfate soils are not suitable for shrimp pond culture due to their high organic matter contents and acidic nature that require a high water exchange rate and low stocking density. A pond built on mangrove soil will also encounter the problems of hydrogen sulfide and ammonia accumulation in the pond bottom. In the acid sulfate soil areas, the soil will develop high acidity when dried and then flooded which will lead to difficulty in stabilizing the pH of the pond water and in inducing the growth of plankton during the culture period.