Most important aquatic crustacean is prawn, which is widely cultured prawn flesh is palatable and rich in glycogen, protein with low fat content.
Types of prawn fishery
1. Shallow water prawn fishery – located on the west coast restricted to shallow waters.
2. Estuaries and back waters or saline lake prawn fishery - The area of production of prawns are the back waters seen along the Western coast, Ennur, Pulicat, Chilka lake and Estuaries of Ganga and Brahmaputra rivers.
3. Freshwater prawn fishery - Prawns are caught from the rivers and lakes throughout India.
4. Marine prawn fishery – Most of the marine prawns are caught along the Indian coast belonging to the family Penaeidae.
A number of species of prawn are distributed in water resources such as Penaeus indicus, Penaeus monodon, Metapenaeus dobsoni and Macrobrachium rosenbergii.
Macrobrachium rosenbergii (Figure 13.11) is commonly seen in rivers, fields and low-saline estuaries. The prawn collected from ponds, river, and paddy fields are transferred to the tanks which are aerated. For fertilization, one pair of prawn are kept in a separate tank. After mating, the eggs are laid. Spawning tanks of different sizesshould be prepared with proper aeration. Temperature (240 C – 300 C) and pH (7- 8) should be maintained in the hatching tank. The eggs hatch into first and second stage larva. Artificial feed is supplied. Young ones of 5cm length (60 days old) can be reared in fresh or slightly brackish water ponds and rice fields. Harvesting of prawns can be done twice in a year.
Several factors that determine the success of marine prawn culture includes selection of site, water quality, soil quality and availability of seed.
For the preparation of ponds for algal growth and for the subsequent stocking of prawns it is essential to drain off the water and sundry the bottom followed by light tilling.
Agricultural lime should be applied to absorb excess CO2 and to supply calcium which is required for moulting. Fertilizers like rice, bran, poultry, and cattle dung are used to increase the fertility of the soil. Prawns are commonly caught in crafts and gears using different types of nets such as cast nets, bag nets, drag nets, trawl nets and barrier nets. Preservation of prawns is done by peeling and deveining or by cooking and peeling.