Extensive Culture System Shrimp Farming in Bangladesh ; According to Md. Mahbubur Rahman Khan, Director General, Department of Fisheries, at present shrimp cultivation is being done by following three patterns based on alternation of crops.
Year round shrimp cultivation: This pattern of farming system is observed around south-western part where water salinity is comparatively higher during 8-9 months of the year. Rice farming usually is not profitable in this type of saline zone.
Shrimp alternation with rice: This pattern is a more common farming system found mainly in Khulna, Bagerhat and part of Satkhira district. Shrimp are grown here from February to July when water salinity favours shrimp growth. Because of the rain during June- July, the salinity goes down and then shrimp farms are able to plant rice by reducing water depth. Deeper parts of shrimp farms are used to keep white fish, a valuable by-product that comes from shrimp farms.
Shrimp alternation with salt: This is the farming system prevailing in and around Cox's Bazar district. Farmers use shrimp land for salt production from December to May. From June to September, the same land is used for shrimp production. Deeper canals inside the salt-cum-shrimp farms are stocked with shrimp PL during February-March. After closing salt production during May, farms are inundated by tidal water to grow shrimp. Further to the above the following information is provided by the director general.
Extensive Culture System Shrimp Farming in Bangladesh
This is the main type of culture system prevailing in the majority of farms. This is also called 'traditional farming system'. These farms are mostly rice fields converted to shrimp ponds with dikes up to a height of about 0.5 m to 1.0 m, width about 0.3 m to 0.6 m and to retain at least a layer of 0.4 to 0.5 meter of water. Ponds are heterogeneous in size and shape. Pond size varies from 0.4 to 200 ha
.
Most of this type of shrimp farms depend on tidal water from adjacent rivers and canals. Some farms however lack direct connection with water source; such farms are situated beyond the direct connection with a river or canal and share brackish water through other farms.
Extensive type of farms change water through sluice gates constructed either by wood or concrete. Smaller farms use wooden gates while larger farms construct concrete sluice gates. There are two types of concrete structure; one is box type and the other is pipe type. Both the gates are used to close and open by wooden shutter. Most of the farms use the same sluice as drainage and flushing sluice. Very few farms have separate flushing and drainage gates.
There is another type of closed shrimp farms fed by pump machines from adjacent canals because tidal height does not allow water intake because of higher land elevation inside these farms. They have no scope for water exchange.
Most of the farms stock PL in several instalments depending on availability of PL and stocking density varies from about 10000 to 20000 PL per ha.
The shrimp farmers usually use very small inputs in the farm. The inputs include, lime, urea, TSP, cow dung, rice or wheat bran, fish meal and oil cake etc. They use no measure before stocking. The production of these farms is very low, varying from 76 to 147 kg/ha.
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