Zero-water exchange shrimp farming systems (extensive) in the periphery of Chilka lagoon, Orissa, India

The extensive zero-water exchange shrimp farming system in the periphery of Chilka lagoon (Orissa, India) was studied. The study aimed to describe this unique farming system with special reference to dynamics of macrozoobenthos, production characteristics and economics. The study conducted was based on a general survey as well as monitoring of five individual farms over a complete production cycle. The farming practice in this area is characterized by complete absence of water exchange during rearing. Ponds in this area are generally shallow (mean 72 cm). Most of the water and soil quality characteristics of these farms are within acceptable levels. Macrozoobenthos belonging to 12 taxa were collected, amphipods (81%) and polychaetes (13%) being most numerous. Overall macrobenthic density of farms studied varied from 968 to 11,470 individuals/m² with a gross mean of 5644 individuals/m². There was no general pattern to the variation in abundance of various taxa in different phases of the rearing cycle, suggesting a low predatory pressure by shrimp in the farms studied. Shrimp production was highly variable (91–250 kg/ha), but generally low with a mean of 145 kg/ha. The net income of these farms was estimated to be Rs. 63,250 per crop per ha. Compared with shrimp farming system with regular water exchange in the same area, Chilka farms generated high benefit-cost ratio indicating high profitability and sustainability.