Freshwater prawn farm
Encyclopedia
A freshwater prawn farm is an aquaculture
business designed to raise and produce freshwater prawn
or shrimp
for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farm
ing. Unique problems are introduced by the developmental life cycle of the main species (the giant river prawn
, Macrobrachium rosenbergii).
The global annual production of freshwater prawns (excluding crayfish
and crab
s) in 2003 was about 280,000 tons, of which China
produced some 180,000 tons, followed by India
and Thailand
with some 35,000 tons each. Additionally, China produced about 370,000 tons of Chinese river crab (Eriocheir sinensis).
Macrobrachium
. Until 2000, the only species farmed was the Giant river prawn
(Macrobrachium rosenbergii, also known as the Malaysian prawn). Since then, China
has begun farming the Oriental river prawn (M. nipponense) in large quantities, and India
farms a small amount of monsoon river prawn (M. malcolmsonii). In 2003, these three species accounted for all farmed freshwater prawns, about two thirds M. rosenbergii and one third M. nipponense.
There are about 200 species in the genus Macrobrachium. They occur throughout the tropics and subtropics on all continents except Europe.
, but their larval stages require brackish water
to survive.
Males can reach a body size of 32 cm;females grow to 25 cm. In mating, the male deposits spermatophore
s on the underside of the female's thorax, between the walking legs. The female then extrudes eggs, which pass through the spermatophores. The female carries the fertilized eggs with her until they hatch; the time may vary, but is generally less than three weeks. A large female may lay up to 100,000 eggs.
From these eggs hatch zoeae, the first larval stage of crustacean
s. They go through several larval stages before metamorphosing into postlarvae, at which stage they are about 8 mm long and have all the characteristics of adults. This metamorphosis usually takes place about 32 to 35 days after hatching. These postlarvae then migrate back into freshwater.
There are three different morphotypes of males. The first stage is called "small male" (SM); this smallest stage has short, nearly translucent claws. If conditions allow, small males grow and metamorphose into "orange claws" (OC), which have large orange claws on their second chelipeds, which may have a length of 0.8 to 1.4 their body size. OC males later may transform into the third and final stage, the "blue claw" (BC) males. These have blue claws, and their second chelipeds may become twice as long as their body.
Male M. rosenbergii have a strict hierarchy: the territorial BC males dominate the OCs, which in turn dominate the SMs. The presence of BC males inhibts 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 who have undergone their pre-mating molt will cooperate with any male to reproduce. BC males protect the female until their shell has hardened, OCs and SMs show no such behavior.
, and spread then 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 farm
ing. 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 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 blue-claws. 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, shunting the growth of other individuals.
The FAO
considers the ecological impact of freshwater prawn farming to be less severe than in shrimp farm
ing. The prawns are cultured at much lower densities, meaning less concentrated waste products and a lesser danger of the ponds becoming breeding places for diseases. The growout ponds do not salinate agricultural land, as do those of inland marine shrimp farms. Freshwater prawn farms do not endanger mangrove
s, and are better amenable to small-scale businesses run by a family. However, like marine farmed shrimp, M. rosenbergii is also susceptible to a variety of viral
or bacterial diseases, including white tail disease, also called "white muscle disease".
, Bangladesh
, and Vietnam
. In the United States
, there are only a few hundred small farms for M. rosenbergii with an overall production of just about 50 tonnes in 2003. The U.S. is, though, the largest producer of farmed crayfish
. In 2003, U.S. farms produced 33,500 tonnes of red swamp crawfish
(Procambarus clarkii), a crayfish species native to North America
.
" and "prawn
" is sometimes blurred. Recent aquaculture literature increasingly uses the term "prawn" only for the freshwater forms of palaemonids and "shrimp" for the marine penaeids.
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
business designed to raise and produce freshwater prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
or shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farm
Shrimp farm
A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing. Unique problems are introduced by the developmental life cycle of the main species (the giant river prawn
Giant river prawn
Macrobrachium rosenbergii, also known as the giant river prawn, giant freshwater prawn, Malaysian prawn, freshwater scampi , or cherabin, is a species of freshwater shrimp native to the Indo-Pacific region,...
, Macrobrachium rosenbergii).
The global annual production of freshwater prawns (excluding crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
and crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s) in 2003 was about 280,000 tons, of which China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
produced some 180,000 tons, followed by India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
with some 35,000 tons each. Additionally, China produced about 370,000 tons of Chinese river crab (Eriocheir sinensis).
Species
All farmed freshwater prawns today belong to the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Macrobrachium
Macrobrachium
Macrobrachium is a genus of freshwater shrimp characterised by the extreme enlargement of the second pair of pereiopods, at least in the male...
. Until 2000, the only species farmed was the Giant river prawn
Giant river prawn
Macrobrachium rosenbergii, also known as the giant river prawn, giant freshwater prawn, Malaysian prawn, freshwater scampi , or cherabin, is a species of freshwater shrimp native to the Indo-Pacific region,...
(Macrobrachium rosenbergii, also known as the Malaysian prawn). Since then, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
has begun farming the Oriental river prawn (M. nipponense) in large quantities, and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
farms a small amount of monsoon river prawn (M. malcolmsonii). In 2003, these three species accounted for all farmed freshwater prawns, about two thirds M. rosenbergii and one third M. nipponense.
There are about 200 species in the genus Macrobrachium. They occur throughout the tropics and subtropics on all continents except Europe.
Biology of Macrobrachium rosenbergii
Giant river prawns live in turbid freshwaterFreshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
, but their larval stages require brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
to survive.
Males can reach a body size of 32 cm;females grow to 25 cm. In mating, the male deposits spermatophore
Spermatophore
A spermatophore or sperm ampulla is a capsule or mass created by males of various animal species, containing spermatozoa and transferred in entirety to the female's ovipore during copulation...
s on the underside of the female's thorax, between the walking legs. The female then extrudes eggs, which pass through the spermatophores. The female carries the fertilized eggs with her until they hatch; the time may vary, but is generally less than three weeks. A large female may lay up to 100,000 eggs.
From these eggs hatch zoeae, the first larval stage of crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. They go through several larval stages before metamorphosing into postlarvae, at which stage they are about 8 mm long and have all the characteristics of adults. This metamorphosis usually takes place about 32 to 35 days after hatching. These postlarvae then migrate back into freshwater.
There are three different morphotypes of males. The first stage is called "small male" (SM); this smallest stage has short, nearly translucent claws. If conditions allow, small males grow and metamorphose into "orange claws" (OC), which have large orange claws on their second chelipeds, which may have a length of 0.8 to 1.4 their body size. OC males later may transform into the third and final stage, the "blue claw" (BC) males. These have blue claws, and their second chelipeds may become twice as long as their body.
Male M. rosenbergii have a strict hierarchy: the territorial BC males dominate the OCs, which in turn dominate the SMs. The presence of BC males inhibts 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 who have undergone their pre-mating molt will cooperate with any male to reproduce. BC males protect the female until their shell has hardened, OCs and SMs show no such behavior.
Technology
Giant River Prawns have been farmed using traditional methods in south-east 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 HawaiiHawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, and spread then first to Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
and then to other countries.
The technologies used in freshwater prawn farming are basically the same as in marine shrimp farm
Shrimp farm
A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing. 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 penaeid shrimp
Penaeidae
Penaeidae is a family of prawns, although they are often referred to as penaeid shrimp. It contains many species of economic importance, such as the tiger prawn , whiteleg shrimp, Atlantic white shrimp and Indian prawn. Many prawns are the subject of commercial fishery, and farming, both in marine...
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 blue-claws. 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, shunting the growth of other individuals.
The FAO
Fão
Fão is a town in Esposende Municipality in Portugal....
considers the ecological impact of freshwater prawn farming to be less severe than in shrimp farm
Shrimp farm
A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing. The prawns are cultured at much lower densities, meaning less concentrated waste products and a lesser danger of the ponds becoming breeding places for diseases. The growout ponds do not salinate agricultural land, as do those of inland marine shrimp farms. Freshwater prawn farms do not endanger mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
s, and are better amenable to small-scale businesses run by a family. However, like marine farmed shrimp, M. rosenbergii is also susceptible to a variety of viral
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
or bacterial diseases, including white tail disease, also called "white muscle disease".
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 TaiwanTaiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
, and Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, there are only a few hundred small farms for M. rosenbergii with an overall production of just about 50 tonnes in 2003. The U.S. is, though, the largest producer of farmed crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
. In 2003, U.S. farms produced 33,500 tonnes of red swamp crawfish
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...
(Procambarus clarkii), a crayfish species native to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
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 farmShrimp farmA shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing and are discussed in that article.
Footnotes
The terminology is sometimes confusing as the distinction between "shrimpShrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
" and "prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
" is sometimes blurred. Recent aquaculture literature increasingly uses the term "prawn" only for the freshwater forms of palaemonids and "shrimp" for the marine penaeids.