Freshwater prawn farming
A freshwater prawn farm is an
The global annual production of freshwater prawns (excluding
Species
All farmed freshwater prawns today belong to the
About 200 species in the genus Macrobrachium live in the tropical and subtropical climates on all continents except Europe and Antarctica.
Biology of Macrobrachium rosenbergii
Giant river prawns live in turbid
From these eggs hatch
There are three different
Male M. rosenbergii prawns have a strict hierarchy: the territorial BC males dominate the OCs, which in turn dominate the SMs. The presence of BC males inhibits the growth of SMs and delays the metamorphosis of OCs into BCs; an OC will keep growing until it is larger than the largest BC male in its neighbourhood before transforming. All three male stages are sexually active, though, and females which have undergone their premating molt will cooperate with any male to reproduce. BC males protect the females until their shells have hardened; OCs and SMs show no such behavior.
Technology
Giant river prawns have been farmed using traditional methods in Southeast Asia for a long time. First experiments with artificial breeding cultures of M. rosenbergii were done in the early 1960s in Malaysia, where it was discovered that the larvae needed brackish water for survival. Industrial-scale rearing processes were perfected in the early 1970s in Hawaii, and spread first to Taiwan and Thailand, and then to other countries.
The technologies used in freshwater prawn farming are basically the same as in marine shrimp farming. Hatcheries produce postlarvae, which then are grown and acclimated in nurseries before being transferred into growout ponds, where the prawns are then fed and grown until they reach marketable size. Harvesting is done by either draining the pond and collecting the animals ("batch" harvesting) or by fishing the prawns out of the pond using nets (continuous operation).
Due to the aggressive nature of M. rosenbergii and the hierarchy between males, stocking densities are much lower than in marine penaeid shrimp farms. Intensive farming is not possible due to the increased level of cannibalism, so all farms are either stocked semi-intensively (4 to 20 postlarvae per square metre) or, in extensive farms, at even lower densities (1 to 4/m2). The management of the growout ponds must take into account the growth characteristics of M. rosenbergii: the presence of blue-claw males inhibits the growth of small males, and delays the metamorphosis of OC males into BCs. Some farms fish off the largest prawns from the pond using seines to ensure a healthy composition of the pond's population, designed to optimize the yield, even if they employ batch harvesting. The heterogeneous individual growth of M. rosenbergii makes growth control necessary even if a pond is stocked newly, starting from scratch: some animals will grow faster than others and become dominant BCs, stunting the growth of other individuals.
The
Economics
The global annual production of freshwater prawns in 2003 was about 280,000 tonnes, of which China produced some 180,000 tonnes, followed by India and Thailand with some 35,000 tonnes each. Other major producer countries are Taiwan, Bangladesh, and Vietnam. In the United States, only a few hundred small farms for M. rosenbergii produced about 50 tonnes in 2003.
See also
- The technologies used in freshwater prawn farming, but also the ecological problems associated with this industry, are basically the same as for marine shrimp farmingand are discussed in that article.
References
- ^ New, M. B.: Farming Freshwater Prawns; FAO Fisheries Technical Paper 428, 2002. ISSN 0429-9345.
- ^ Data extracted from the FAO Fisheries Global Aquaculture Production Database for freshwater crustaceans. The most recent data sets are for 2003 and sometimes contain estimates. Accessed June 28, 2005.
- ^ Wynne, F.: Grow-out Culture of Freshwater Prawns in Kentucky, 2000. Last accessed July 4, 2005.
- ; accessed June 30, 2005. Has images.
- ^ Tonguthai, K.: Diseases of the Freshwater Prawn, Macrobrachium rosenbergii Archived 2005-12-11 at the Wayback Machine, AAHRI Newsletter 4(2), Aquatic Animal Health Research Institute, Bangkok University; December 1997.
- ^ Sahul Hameed, A. S.: White tail disease of Macrobrachium rosenbergii, NACA, 2003.
- ^ Sahul Hameed, A. S.: White Tail Disease - Disease Card[permanent dead link], NACA, 2005.