Marine shrimp farming is a century-old practice in many Asian countries. Until a decade ago, this commodity was generally considered a secondary crop in traditional fish farming practices. Shrimp fry trapped in salt beds, coastal paddy fields or brackishwater fishponds are allowed to grow to marketable size and harvested as secondary crop. However, in recent years when higher income are derived from the harvest of shrimp than the principal crop, many farmers have converted their rice fields, salt beds and fishponds into shrimp farms.
In the traditional farming system, the ponds are stocked with fry either collected from the wild or concentrated through tidal water entering the ponds. Shrimp production is inconsistent and varies from year to year due to the dependence on seasonal supply of fry from the wild. Pond yield is also low (100–300 kg/ha/ year) because of inefficient control of predators and competitors, full dependence on natural food and inadequate pond depth.
Some improvements of the traditional farming methods have been made in the past years. Stocking density of shrimp ponds can be increased through concentration of fry by pumping more tidal water into the pond. Pond depth is increased to minimize fluctuations of environmental parameters. As a result, pond yield has correspondingly increased. However, expansion of the shrimp farming industry is still restricted due to the inconsistency in fry supply.
The success in the mass production of hatchery-bred shrimp fry in the 1970's has accelerated shrimp farming development in the region. With improved pond culture techniques, yield from traditional shrimp ponds has been raised to 500–800 kg/ha/year without supplementary feeding. Pond yield can be further increased to 5–10 tons through supplementary feeding and intensive pond management.
The long gestation period in the development of shrimp farming practice may be due to inadequate technical and financial inputs to effectively demonstrate its commercial viability. Shrimp farming has now developed into an important export-oriented food industry especially in South Asian countries. The perception of an unlimited market demand, high export price, generation of employment and increase in foreign exchange earnings may have encouraged many countries in the region rich in aquatic resources to place high emphasis on the development of the shrimp culture industry.
