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Shrimp farm

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

   Shrimp growout pond on a farm in South Korea.
   Enlarge
   Shrimp growout pond on a farm in South Korea.

   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 USA, Japan and Western Europe. The total global
   production of farmed shrimp reached more than 1.6 million tonnes in
   2003, representing a value of nearly 9,000 million U.S. dollars. About
   75% of farmed shrimp is produced in Asia, in particular in China and
   Thailand. The other 25% is produced mainly in Latin America, where
   Brazil is the largest producer. The largest exporting nation is
   Thailand.

   Shrimp farming has changed from traditional, small-scale businesses in
   Southeast Asia into a global industry. Technological advances have led
   to growing shrimp at ever higher densities, and broodstock is shipped
   world-wide. Virtually all farmed shrimp are penaeids (i.e., shrimp of
   the family Penaeidae), and just two species of shrimp—the Penaeus
   vannamei (Pacific white shrimp) and the Penaeus monodon (giant tiger
   prawn)—account for roughly 80% of all farmed shrimp. These industrial
   monocultures are very susceptible to diseases, which have caused
   several regional wipe-outs of farm shrimp populations. Increasing
   ecological problems, repeated disease outbreaks, and pressure and
   criticism from both NGOs and consumer countries led to changes in the
   industry in the late 1990s and generally stronger regulation by
   governments. In 1999, a program aimed at developing and promoting more
   sustainable farming practices was initiated, including governmental
   bodies, industry representatives, and environmental organizations.

History and geography

   Shrimp farming has been done for centuries in Asia, using traditional
   low-density methods. Indonesian brackish water ponds called tambaks can
   be traced back as far as the 15th century. Shrimp were farmed on a
   small scale in ponds, in monocultures or together with other species
   such as milkfish, or in rotation with rice, using the rice paddies for
   shrimp cultures during the dry season, when no rice could be grown.
   Such traditional cultures often were small operations in coastal areas
   or on river banks. Mangrove areas were favoured because of their
   naturally abundant supply of shrimp. Wild juvenile shrimp were trapped
   in ponds and reared on naturally occurring organisms in the water until
   they had the desired size and then were harvested.

   The origins of industrial shrimp farming can be traced back to the
   1930s, when Kuruma shrimp (Penaeus japonicus) was spawned and
   cultivated for the first time in Japan. By the 1960s, a small shrimp
   farming industry had appeared in Japan. Commercial shrimp farming began
   in the late 1960s and early 1970s. Technological advances led to ever
   more intensive forms of shrimp farming, and the growing market demand
   led to a proliferation of shrimp farms throughout the world,
   concentrated in tropical and sub-tropical regions. The growing consumer
   demand coincided in the early 1980s with faltering wild shrimp catches,
   creating a veritable boom in shrimp aquaculture. Taiwan was amongst the
   early adopters and a major producer in the 1980s; its production
   collapsed beginning in 1988 due to poor management practices and
   disease. In Thailand, large-scale intensive shrimp farming expanded
   rapidly from 1985. In South America, shrimp farming was pioneered by
   Ecuador, where it expanded dramatically from 1978. Brazil had been
   active in shrimp farming since 1974, but the trade really boomed there
   only in the 1990s, making the country a major producer within a few
   years. Today, there are marine shrimp farms in over fifty countries.

Farming methods

   When shrimp farming emerged in the 1970s as an economically viable
   alternative to satisfy growing market demands that had surpassed the
   capacity of the wild shrimp fishery, the subsistence farming methods of
   old were rapidly replaced by the more intensive practices of an
   export-oriented business. Industrial shrimp farming at first followed
   these traditional methods with so-called extensive shrimp farms, but
   compensated for the low yield per area with increased pond sizes:
   instead of ponds of just a few hectares, ponds of sizes up to 100 ha
   (one km²) were used in some places. The initially largely unregulated
   business boomed, and in many regions whole coastlines were transformed
   and huge areas of mangroves cleared. Further technological advances
   made more intensive farming practices possible that could achieve
   higher yields per area while using less land. Semi-intensive and
   intensive farms appeared, where the shrimp were reared on artificial
   feeds and ponds were actively managed. Although there are still many
   extensive farms, new farms typically are of the (semi-)intensive kind.

   Until the mid-1980s, most shrimp farms were stocked with young wild
   shrimp, called postlarvae, typically caught by local fishermen.
   Postlarvae fishing became an important economic sector in many
   countries. To counteract the beginning depletion of fishing grounds and
   to ensure a steady supply of young shrimp to farms, the industry
   started raising shrimp from the egg and maintaining adult shrimp for
   reproductive purposes in specialized installations called hatcheries.

Life cycle of shrimp

   A nauplius of a shrimp.
   Enlarge
   A nauplius of a shrimp.

   Shrimp mature and breed only in a marine habitat. The females lay
   50,000 to 1 million eggs, which hatch after some 24 hours into tiny
   nauplii. These nauplii feed on yolk reserves within their body and then
   undergo a metamorphosis into zoeae. This second larval stage feeds in
   the wild on algae and after a few days metamorphoses again into the
   third stage to become myses. The myses already look akin to tiny shrimp
   and feed on algae and zooplankton. After another three to four days
   they metamorphose a final time into postlarvae: young shrimp having all
   the characteristics of adults. The whole process takes about 12 days
   from hatching. In the wild, the postlarvae then migrate into estuaries,
   which are rich in nutrients and low in salinity. There they grow and
   eventually migrate back into open waters when they mature. Adult shrimp
   are benthic animals living primarily on the sea bottom.

Technologies

   In shrimp farming, this lifecycle occurs under controlled conditions.
   The reasons to do so include more intensive farming, improved size
   control resulting in more uniformly sized shrimp, and better predator
   control, but also the ability to speed up the cycle by controlling the
   climate (especially in farms in the temperate zones, using
   greenhouses). There are three different stages:
     * Hatcheries breed shrimp and produce nauplii or even postlarvae,
       which they sell to farms. Large shrimp farms maintain their own
       hatcheries and sell nauplii or postlarvae to smaller farms in the
       region.
     * Nurseries are those parts of a shrimp farm where postlarvae are
       grown and accustomed to the marine conditions in the growout ponds.
     * In the growout ponds the shrimp are grown from juveniles to
       marketable size, which takes between three to six months.

   Most farms produce one to two harvests a year; in tropical climates, a
   farm may even produce three. Because of the need for salt water, shrimp
   farms are located on or near a coast. Inland shrimp farms have also
   been tried in some regions, but the need to ship salt water and
   competition for land with agricultural users led to problems. Thailand
   banned inland shrimp farms in 1999.

Hatcheries

   Tanks in a shrimp hatchery.
   Enlarge
   Tanks in a shrimp hatchery.

   Small-scale hatcheries are very common throughout Southeast Asia. Often
   run as family businesses and using a low-technology approach, they use
   small tanks (less than ten tons) and often low animal densities. They
   are susceptible to disease, but due to their small size, they can
   typically restart production quickly after disinfection. The survival
   rate is anywhere between zero and 90%, depending on a wide range of
   factors, including disease, the weather, and the experience of the
   operator.

   Greenwater hatcheries are medium-sized hatcheries using large tanks
   with low animal densities. To feed the shrimp larvae, an algal bloom is
   induced in the tanks. The survival rate is about 40%.

   Galveston hatcheries (named after Galveston, Texas, where they were
   developed) are large-scale, industrial hatcheries using a closed and
   tightly controlled environment. They breed the shrimp at high densities
   in large (15 to 30 ton) tanks. Survival rates vary between zero and
   80%, but typically achieve 50%.

   In hatcheries, the developing shrimp are fed on a diet of algae and
   later also brine shrimp nauplii, sometimes (especially in industrial
   hatcheries) augmented by artificial diets. The diet of later stages
   also includes fresh or freeze-dried animal protein, for example krill.
   Nutrition and medication (such as antibiotics) fed to the brine shrimp
   nauplii are passed on to the shrimp that eat them.

Nurseries

   Farmers transferring postlarvae from the tanks on the truck to a
   growout pond.
   Enlarge
   Farmers transferring postlarvae from the tanks on the truck to a
   growout pond.

   Many farms have nurseries where the postlarval shrimp are grown into
   juveniles for another three weeks in separate ponds, tanks, or
   so-called raceways. A raceway is a rectangular, long, shallow tank
   through which water flows continuously.

   In a typical nursery, there are 150 to 200 animals per square metre.
   They are fed on a high-protein diet for at most about three weeks
   before they are moved to the growout ponds. At that time, they weigh
   between one and two grams. The water salinity is adjusted gradually to
   that of the growout ponds.

   Farmers refer to postlarvae as "PLs", with the number of days suffixed
   (i.e., PL-1, PL-2, etc.). They are ready to be transferred to the
   growout ponds after their gills have branched, which occurs around
   PL-13 to PL-17 (about 25 days after hatching). Nursing is not
   absolutely necessary, but is favored by many farms because it makes for
   better food utilization, improves the size uniformity, helps utilize
   the infrastructure better, and can be done in a controlled environment
   to increase the harvest. The main disadvantage of nurseries is that
   some of the postlarval shrimp die upon the transfer to the growout
   pond.

   Some farms do not use a nursery but stock the postlarvae directly in
   the growout ponds after having acclimated them to the appropriate
   temperature and salinity levels in an acclimation tank. Over the course
   of a few days, the water in these tanks is changed gradually to match
   that of the growout ponds. The animal density should not exceed
   500/liter for young postlarvae and 50/liter for larger ones, such as
   PL-15.

Growout

   Shrimp pond with paddlewheel aerators.
   Enlarge
   Shrimp pond with paddlewheel aerators.

   In the growout phase, the shrimp are grown to maturity. The postlarvae
   are transferred to ponds where they are fed until they reach marketable
   size, which takes about another three to six months. Harvesting the
   shrimp is done by fishing them from the ponds using nets or by draining
   the ponds. Pond sizes and the level of technical infrastructure vary.

   Extensive shrimp farms using traditional low-density methods are
   invariably located on a coast and often in mangrove areas. The ponds
   range from just a few to more than 100 hectares; shrimp are stocked at
   low densities (2-3 animals per square metre, or 25,000/ha). The tides
   provide for some water exchange, and the shrimp feed on naturally
   occurring organisms. In some areas, farmers even grow wild shrimp by
   just opening the gates and impounding wild larvae. Prevalent in poorer
   or less developed countries where land prices are low, extensive farms
   produce annual yields from 50 to 500 kg/ha of shrimp (head-on weight).
   They have low production costs (US$1–3/kg live shrimp), are not very
   labor intensive, and do not require advanced technical skills.

   Semi-intensive farms do not rely on tides for water exchange but use
   pumps and a planned pond layout. They can therefore be built above the
   high tide line. Pond sizes range from 2 to 30 ha; the stocking
   densities range from 10 to 30/m² (100,000–300,000/ha). At such
   densities, artificial feeding using industrially prepared shrimp feeds
   and fertilizing the pond to stimulate the growth of naturally occurring
   organisms become a necessity. Annual yields range from 500 to 5,000
   kg/ha, while production costs are in the range of US$2–6/kg live
   shrimp. With densities above 15 animals per square metre, aeration is
   often required to prevent oxygen depletion. Productivities vary
   depending upon water temperature, thus it is common to have larger
   sized shrimp in some seasons than in others.

   Intensive farms use even smaller ponds (0.1–1.5 ha) and even higher
   stocking densities. The ponds are actively managed: they are aereated,
   there is a high water exchange to remove waste products and maintain
   water quality, and the shrimp are fed on specially designed diets,
   typically in the form of formulated pellets. Such farms produce annual
   yields between 5,000 and 20,000 kg/ha; a few super-intensive farms can
   produce as much as 100,000 kg/ha. They require an advanced technical
   infrastructure and highly trained professionals for constant monitoring
   of water quality and other pond conditions; their production costs are
   in the range of US$4–8/kg live shrimp.

   Estimates on the production characteristics of shrimp farms vary. Most
   studies agree that about 55–60% of all shrimp farms worldwide are
   extensive farms, another 25–30% are semi-intensive, the rest being
   intensive farms. Regional variation is high, though, and [Tacon 2002]
   reports wide discrepancies in the percentages claimed for individual
   countries by different studies.

Feeding the shrimps

   While extensive farms mainly rely on the natural productivity of the
   ponds, more intensively managed farms rely on artificial shrimp feeds,
   either exclusively or as a supplement to the organisms that naturally
   occur in a pond. A food chain is established in the ponds, based on the
   growth of phytoplankton. Fertilizers and mineral conditioners are used
   to boot the growth of the phytoplankton to accelerate the growth of the
   shrimps. Waste from the artificial food pellets and excrements of the
   shrimps can lead to the eutrophication of the ponds.

   Artifical feeds come in the form of specially formulated, granulated
   pellets that disintegrate quickly. Up to 70% of such pellets are
   wasted, as they decay before the shrimps have eaten them. The shrimps
   are fed two to four times daily; the feeding can be done manually
   either from ashore or from boats, or using mechanized feeders
   distributed all over a pond. The feed conversion rate, i.e. the amount
   of food needed to produce a unit (e.g. one kilogram) of shrimp, is
   claimed by the industry to be around 1.2–2 in modern farms, but this is
   an optimum value that is not always attained in practice. For a farm to
   be profitable, a feed conversion rate below 2.5 is necessary; in older
   farms or under suboptimal pond conditions, the ratio may easily rise to
   4:1.

Farmed species

   Although there are many species of shrimp and prawn, only a few of the
   larger ones are actually cultivated, all of which belong to the family
   of penaeids ( family Penaeidae), and within it to the genus Penaeus.
   Many species are unsuitable for farming: they are too small to be
   profitable, or simply stop growing when crowded together, or are too
   susceptible to diseases. The two species dominating the market are:
     * Pacific white shrimp (Litopenaeus vannamei, also called "whiteleg
       shrimp") is the main species cultivated in western countries.
       Native to the Pacific coast from Mexico to Peru, it grows to a size
       of 23 cm. P. vannamei accounts for 95% of the production in Latin
       America. It is easy to breed in captivity, but succumbs to the
       Taura disease.
     * Giant tiger prawn (P. monodon, also known as "black tiger shrimp")
       occurs in the wild in the Indian Ocean and in the Pacific Ocean
       from Japan to Australia. The largest of all the cultivated shrimp,
       it can grow to a length of 36 cm and is farmed in Asia. Because of
       its susceptibility to whitespot disease and the difficulty of
       breeding it in captivity, it is gradually being replaced by L.
       vannamei since 2001.

   Together, these two species account for about 80% of the whole farmed
   shrimp production. Other species being bred are:
   Kuruma shrimp in an aquaculture observation tank in Taiwan.
   Enlarge
   Kuruma shrimp in an aquaculture observation tank in Taiwan.
     * Western blue shrimp (P. stylirostris) was a popular choice for
       shrimp farming in the western hemisphere, until the IHHN virus
       wiped out nearly the whole population in the late 1980s. A few
       stocks survived and became resistant against this virus. When it
       was discovered that some of these were also resistant against the
       Taura virus, some farms again bred P. stylirostris from 1997 on.
     * Chinese white shrimp (P. chinensis, also known as the fleshy prawn)
       occurs along the coast of China and the western coast of Korea and
       is being farmed in China. It grows to a maximum length of only
       18 cm, but tolerates colder water (min. 16° C). Once a major factor
       on the world market, it is today used almost exclusively for the
       Chinese domestic market after a virus disease wiped out nearly all
       the stocks in 1993.
     * Kuruma shrimp (P. japonicus) is farmed primarily in Japan and
       Taiwan, but also in Australia; the only market is in Japan, where
       live Kuruma shrimp reach prices of the order of US$100 per pound
       ($220/kg).
     * Indian white shrimp (P. indicus) is a native of the coasts of the
       Indian Ocean and is widely bred in India, Iran and the Middle East
       and along the African shores.
     * Banana shrimp (P. merguiensis) is another cultured species from the
       coastal waters of the Indian Ocean, from Oman to Indonesia and
       Australia. It can be grown at high densities.

   Several other species of Penaeus play only a very minor role in shrimp
   farming. Some other kinds of shrimp also can be farmed, e.g. the
   "Akiami paste shrimp" or Metapenaeus spp. Their total production from
   aquaculture is of the order of only about 25,000 tonnes per year, small
   in comparison to that of the penaeids.

Diseases

   There are a variety of lethal viral diseases that affect shrimp. In the
   densely populated, monocultural farms such virus infections spread
   rapidly and may wipe out whole shrimp populations. A major transfer
   vector of many of these viruses is the water itself; and thus any virus
   outbreak also carries the danger of decimating shrimp living in the
   wild.

   Yellowhead disease, called Hua leung in Thai, affects P. monodon
   throughout Southeast Asia. It had been reported first in Thailand in
   1990. The disease is highly contagious and leads to mass mortality
   within 2 to 4 days. The cephalothorax of an infected shrimp turns
   yellow after a period of unusually high feeding activity ending
   abruptly, and the then moribund shrimp congregate near the surface of
   their pond before dying.

   Whitespot syndrome is a disease caused by a family of related viruses.
   First reported in 1993 from Japanese P. japonicus cultures, it spread
   throughout Asia and then to the Americas. It has a wide host range and
   is highly lethal, leading to mortality rates of 100% within days.
   Symptoms include white spots on the carapace and a red hepatopancreas.
   Infected shrimp become lethargic before they die.

   Taura syndrome was first reported from shrimp farms on the Taura river
   in Ecuador in 1992. The host of the virus causing the disease is P.
   vannamei, one of the two most commonly farmed shrimp. The disease
   spread rapidly, mainly through the shipping of infected animals and
   broodstock. Originally confined to farms in the Americas, it has also
   been propagated to Asian shrimp farms with the introduction of P.
   vannamei there. Birds are thought to be a route of infection between
   farms within one region.

   Infectious Hypodermal and Hematopoietic Necrosis (IHHN) is a disease
   that causes mass mortality among P. stylirostris (as high as 90%) and
   severe deformations in P. vannamei. It occurs in Pacific farmed and
   wild shrimp, but not in wild shrimp on the Atlantic coast of the
   Americas.

   There are also a number of bacterial infections that are lethal to
   shrimp. The most common is vibriosis, caused by the bacterium Vibrio
   spp. The shrimp become weak and disoriented and may have dark wounds on
   the cuticle. The mortality rate can exceed 70%. Another bacterial
   disease is Necrotising hepatopancreatitis (NHP); symptoms include a
   soft exoskeleton and fouling. Most such bacterial infections are
   strongly correlated to stressful conditions such as overcrowded ponds,
   high temperatures, and poor water quality: factors that positively
   influence the growth of bacteria. Treatment is done using antibiotics.
   Importing countries have repeatedly placed import bans on shrimp
   containing various antibiotics. One such antibiotic is chloramphenicol,
   which has been banned in the European Union since 1994, but continues
   to pose problems.

   With their high mortality rates, diseases represent a very real danger
   to shrimp farmers, who may lose their income for the whole year if
   their ponds are infected. Since most diseases cannot yet be treated
   effectively, the industry's efforts are focused on preventing diseases
   to break out in the first place. Active water quality management helps
   avoid poor pond conditions favourable to the spread of diseases, and
   instead of using larvae from wild catches, specific pathogen free
   broodstocks raised in captivity in isolated environments and certified
   not to carry diseases are used increasingly. To avoid introducing
   diseases into such disease-free populations on a farm, there is also a
   trend to create more controlled environments in the ponds of
   (semi-)intensive farms, such as by lining them with plastic to avoid
   soil contact, and by minimizing water exchange in the ponds.

Economy

   A steamed tail-on shrimp
   Enlarge
   A steamed tail-on shrimp

   The total global production of farmed shrimp reached more than 1.6
   million tonnes in 2003, representing a farm-gate value of nearly 9,000
   million U.S. dollars. This accounts for 25% of the total shrimp
   production that year (farming and wild catches combined). The largest
   market for shrimp is the United States, importing more than 500,000
   tonnes of shrimp in 2003. About 250,000 tonnes went to Japan, while the
   four major European shrimp importing countries (France, Spain, the UK,
   and Italy) imported together about another 500,000 tonnes.

   The import prices for shrimp fluctuate wildly. In 2003 the import price
   per kilogram shrimp in the United States was US$ 8.80, slightly higher
   than in Japan at US$8.–. The average import price in the EU was only
   about US$5.–/kg; this much lower value is explained by the fact that
   the EU imports more coldwater shrimp (from catches) that are much
   smaller than the farmed warm water species and thus attain lower
   prices. In addition, Mediterranean Europe prefers head-on shrimp which
   weigh approximately 30% more but have a lower unit price.

   About 75% of the world production of farmed shrimp comes from Asian
   countries; the two leading nations being China and Thailand, closely
   followed by Vietnam, Indonesia, and India. The other 25% are produced
   in the western hemisphere, where the South-American countries (Brazil,
   Ecuador, Mexico) dominate. In terms of export, Thailand is by far the
   leading nation with a market share of more than 30%, followed by China,
   Indonesia, and India, accounting each for about 10%. Other major export
   nations are Vietnam, Bangladesh, and Ecuador. Thailand exports nearly
   all of its production, while China uses most of its shrimp in the
   domestic market. The only other major export nation that has a strong
   domestic market for farmed shrimp is Mexico.

   CAPTION: Aquaculture shrimp production by the major producer nations.

   Region Country Production in 1,000 tonnes, rounded
   1985 86 87 88 89 1990 91 92 93 94 95 96 97 98 99 2000 01 02 03
   Asia China 40 83 153 199 186 185 220 207 88 64 78 89 103 143 170 218
   304 384 493
   Thailand 10 12 19 50 90 115 161 185 223 264 259 238 225 250 274 309 279
   172 298
   Vietnam 8 13 19 27 28 32 36 37 39 45 55 46 45 52 55 90 150 181 232
   Indonesia 25 29 42 62 82 84 116 120 117 107 121 125 127 97 121 118 129
   137 167
   India 13 14 15 20 28 35 40 47 62 83 70 70 67 83 79 97 103 115 113
   Bangladesh 11 15 15 17 18 19 20 21 28 29 32 42 48 56 58 59 55 56 56
   Philippines 29 30 35 44 47 48 47 77 86 91 89 77 41 38 39 41 42 37 37
   Myanmar 0 0 0 0 0 0 0 0 0 0 1 2 2 2 5 5 6 7 19
   Taiwan 17 45 80 34 22 15 22 16 10 8 11 13 6 5 5 6 8 10 13
   Americas Brazil <1 <1 <1 <1 1 2 2 2 2 2 2 3 4 7 16 25 40 60 90
   Ecuador 30 44 69 74 70 76 105 113 83 89 106 108 133 144 120 50 45 47 57
   Mexico <1 <1 <1 <1 3 4 5 8 12 13 16 13 17 24 29 33 48 46 46
   U.S. <1 <1 1 1 <1 <1 2 2 3 2 1 1 1 2 2 2 3 4 5
   Middle East Saudi Arabia 0 0 0 0 <1 <1 <1 <1 <1 <1 <1 <1 1 2 2 2 4 5 9
   Iran 0 0 0 0 0 0 0 <1 <1 <1 <1 <1 <1 1 2 4 8 6 7
   Oceania Australia 0 <1 <1 <1 <1 <1 <1 <1 1 2 2 2 1 1 2 3 3 4 3
   Entries in italics indicate gross estimates in the FAO databases.
   Bolded numbers indicate some recognizeable disease events.

   Disease problems have repeatedly impacted the shrimp production
   negatively. Besides the near-wipeout of P. chinensis in 1993, there
   were outbreaks of viral diseases that led to marked declines in the
   per-country production in 1996/97 in Thailand and repeatedly in
   Ecuador. In Ecuador alone, production suffered heavily in 1989 (IHHN),
   1993 (Taura), and 1999 (whitespot). Another reason for sometimes wild
   changes in shrimp farm output are the import regulations of the
   destination countries, which do not allow shrimp contaminated by
   chemicals or antibiotics to be imported.

   In the 1980s and through much of the 1990s, shrimp farming promised
   high profits. The investments required for extensive farms were low,
   especially in regions with low land prices and wages. For many tropical
   countries, especially those with poorer economies, shrimp farming was
   an attractive business, offering jobs and incomes for poor coastal
   populations and has, due to the high market prices of shrimp, provided
   many developing countries with non-negligible foreign currency
   earnings. Many shrimp farms were funded initially by the World Bank or
   substantially subsidized by local governments.

   In the late 1990s, the economic situation changed. Governments and
   farmers alike were under increasing pressure from NGOs and the consumer
   countries, who criticized the practices of the trade. International
   trade conflicts erupted, such as import bans by consumer countries on
   shrimp containing antibiotics, the United States' shrimp import ban
   against Thailand in 2004 as a measure against Thai shrimp fishers not
   using Turtle Excluder Devices in their nets, or the "anti- dumping"
   case initiated by U.S. shrimp fishers in 2002 against shrimp farmers
   world-wide, which resulted two years later in the U.S. imposing
   anti-dumping tariffs of the order of about 10% against many producer
   countries (except China, which received a 112% duty). Diseases caused
   significant economic losses. In Ecuador, where shrimp farming was a
   major export sector (the other two are Bananas and Oil), the whitespot
   outbreak of 1999 caused an estimated 130,000 workers to lose their
   jobs. Furthermore, shrimp prices dropped sharply in 2000. All of these
   factors contributed to the slowly growing acceptance by farmers that
   improved farming practices were needed, and resulted in tighter
   government regulation of the business, both of which internalized some
   of the external costs that were ignored during the boom years.

Socio-economic aspects

   Shrimp farming offers significant employment opportunities, which may
   help alleviate the poverty of the local coastal populations in many
   areas, if it is properly managed. The published literature on that
   topic shows large discrepancies, and much of the available data is of
   anecdotal nature. Estimates of the labor-intensiveness of shrimp farms
   range from about three times less to three times more than when the
   same area was used for rice paddies, with much regional variation and
   depending on the type of farms surveyed. In general, intensive shrimp
   farming requires more labour per unit area than extensive farming.
   Extensive farms cover much more land area and are often but not always
   located in areas where no agricultural land uses are possible.
   Supporting industries such as feed production or storage, handling, and
   trade companies should also not be neglected, even if not all of them
   are exclusive to shrimp farming.

   Typically, workers on a shrimp farm can get better wages than with
   other employments. A global estimate from one study is that a shrimp
   farm worker can earn 1.5 – 3 times as much as in other jobs; a study
   from India arrived at a salary increase of about 1.6, and a report from
   Mexico states that the lowest paid job at shrimp farms was paid in 1996
   at 1.22 times the average worker salary in the country.

   NGOs have frequently criticized that most of the profits went to large
   conglomerates instead of to the local population. While this may be
   true in certain regions such as Ecuador, where most shrimp farms are
   owned by large companies, it does not apply in all cases. For instance
   in Thailand, most farms are owned by small local entrepreneurs,
   although there is a trend to vertically integrate the industries
   related to shrimp farming from feed producers to food processors and
   trade companies. A 1994 study reported that a farmer in Thailand could
   increase his income by a factor of ten by switching from growing rice
   to farming shrimp. An Indian study from 2003 arrives at similar figures
   for shrimp farming in the East Godavari district in Andhra Pradesh.

   Whether the local population benefits from shrimp farming is also
   dependent on the availability of sufficiently trained people. Extensive
   farms tend to offer mainly seasonal jobs during harvest that do not
   require much training. In Ecuador, many of these positions are known to
   have been filled by migrant workers. More intensive farms have a need
   for year-round labour in more sophisticated jobs.

Marketing

   For commercialization, shrimps are graded and marketed in different
   categories. From complete shrimps (known as "head-on, shell-on" or
   HOSO) to peeled and deveined (P&D), any presentation is available in
   stores. The animals are graded by their size uniformity and then also
   by their count per weight unit, with larger shrimps attaining higher
   prices.

Ecological impacts

   Mangrove estuaries provide a habitat for many animals and plants.
   Enlarge
   Mangrove estuaries provide a habitat for many animals and plants.
   Two false-color images show the widespread conversion of natural
   mangrove swamps to shrimp farms along Pacific Coast of Honduras between
   1987 and 1999. The shrimp farms appear as rows of rectangles. In the
   older image (bottom), mangrove swamps wander through the estuaries of
   several rivers as they reach the Pacific coast. At least one major
   shrimp farm can be seen in this scene in the upper left quadrant,
   verifying that shrimp farming was already underway at the time. By 1999
   (top image), much of the region had been converted to blocks of shrimp
   ponds.
   Enlarge
   Two false-colour images show the widespread conversion of natural
   mangrove swamps to shrimp farms along Pacific Coast of Honduras between
   1987 and 1999. The shrimp farms appear as rows of rectangles. In the
   older image (bottom), mangrove swamps wander through the estuaries of
   several rivers as they reach the Pacific coast. At least one major
   shrimp farm can be seen in this scene in the upper left quadrant,
   verifying that shrimp farming was already underway at the time. By 1999
   (top image), much of the region had been converted to blocks of shrimp
   ponds.

   Shrimp farms of all types, from extensive to super-intensive, can cause
   severe ecological problems wherever they are located. For extensive
   farms, huge areas of mangroves were cleared, reducing biodiversity.
   During the 1980s and 1990s, about 35% of the world's mangrove forests
   have vanished. Shrimp farming was a major cause of this, accounting for
   over a third of it according to one study; other studies report between
   5% and 10% globally, with enormous regional variability. Other causes
   of mangrove destruction are population pressure, logging, pollution
   from other industries, or conversion to other uses such as salt pans.
   Mangroves, through their roots, help stabilize a coastline and capture
   sediments; their removal has led to a marked increase of erosion and
   less protection against floods. Mangrove estuaries are also especially
   rich and productive ecosystems and provide the spawning grounds for
   many species of fish, including many commercially important ones. Many
   countries have protected their mangroves and forbidden the construction
   of new shrimp farms in tidal or mangrove areas. The enforcement of the
   respective laws is often problematic, though, and especially in the
   least developed countries such as Bangladesh, Myanmar, or Vietnam the
   conversion of mangroves to shrimp farms remains an issue.

   Intensive farms, while reducing the direct impact on the mangroves,
   have other problems. Their nutrient-rich effluents (industrial shrimp
   feeds disintegrate quickly, only 30% are actually eaten by the shrimp,
   the rest is wasted) are typically discharged into the environment,
   seriously upsetting the ecological balance. These waste waters contain
   significant amounts of chemical fertilizers, pesticides (used to
   disinfect ponds between uses), and antibiotics that cause severe
   pollution of the environment. Furthermore, releasing antibiotics in
   such ways injects them into the food chain and increases the risks of
   organisms becoming resistant against them.

   Prolonged use of a pond leads to an incremental build-up of a toxic
   sludge at the pond's bottom from waste products and excrements.
   Flushing a pond never completely removes this sludge, and eventually,
   the pond is abandoned, leaving behind a wasteland with the soil made
   unusable for any other purposes due to the high levels of salinity,
   acidity, and toxic chemicals. A typical pond in an extensive farm can
   be used only a few years. An Indian study estimated the time to
   rehabilitate such lands to about 30 years. Thailand has banned inland
   shrimp farms since 1999 because they caused too much destruction of
   agricultural lands due to salination. A Thai study estimated that 60%
   of the shrimp farming area in Thailand was abandoned in the years 1989
   – 1996.

   The global nature of the shrimp farming business and in particular the
   shipment of broodstock and hatchery products throughout the world have
   not only introduced various shrimp species as exotic species, but also
   distributed the diseases the shrimp may carry world-wide. Many
   organizations lobby actively for consumers to avoid buying farmed
   shrimp. Some also advocate the development of more sustainable farming
   methods. A joint programme of the World Bank, the Network of
   Aquaculture Centres in Asia-Pacific (NACA), the WWF, and the FAO was
   established in August 1999 to study and propose improved practices for
   shrimp farming. Some existing attempts at sustainable export-oriented
   shrimp farming marketing the shrimp as "ecologically produced" are
   criticized by NGOs as being dishonest and trivial window-dressing.

   Yet the industry has been slowly changing since about 1999. It has
   adopted the "best management practices" developed by e.g. the World
   Bank et al. programme and instituted educational programmes to promote
   them. Due to the mangrove protection laws enacted in many countries,
   new farms are usually of the (semi-)intensive kind, which are best
   constructed outside of mangrove areas anyway. There is a trend to
   create even more tightly controlled environments in these farms with
   the hope to achieve better disease prevention. Waste water treatment
   has attracted considerable attention; modern shrimp farms routinely
   have effluent treatment ponds where sediments are allowed to settle at
   the bottom and other residuals are filtered. As such improvements are
   costly, the World Bank et al. programme also recommends low-intensity
   polyculture farming for some areas. Since it has been discovered that
   mangrove soils are effective in filtering waste waters and tolerate
   high nitrate levels, the industry has also developed an interest in
   mangrove reforestation, although its contributions in that area are
   still minor. The long-term effects of these recommendations and
   industry trends cannot be evaluated conclusively yet.

Social changes

   Shrimp farming in many cases has far-reaching effects on the local
   coastal population. Especially in the boom years of the 1980s and
   1990s, when the business was largely unregulated in many countries, the
   very fast expansion of the industry caused significant changes that
   sometimes were detrimental to the local population. Conflicts can be
   traced back to two root causes: competition for common resources such
   as land and water, and changes induced by wealth redistribution.

   A significant problem causing much conflict in some regions, for
   instance in Bangladesh, are the land use rights. With shrimp farming, a
   new industry expanded into coastal areas and started to make exclusive
   use of previously public resources. In some areas, the rapid expansion
   resulted in the local coastal population being denied access to the
   coast by a continuous strip of shrimp farms with serious impacts on the
   local fisheries. Such problems were compounded by poor ecological
   practices that caused a degradation of common resources (such as
   excessive use of freshwater to control the salinity of the ponds,
   causing the water table to sink and leading to the salination of
   freshwater aquifers by an inflow of salt water). With growing
   experience, countries usually introduced stronger governmental
   regulations and have taken steps to mitigate such problems, for
   instance through land zoning legislations. Some late adopters have even
   managed to avoid some problems through proactive legislation, e.g.
   Mexico. The situation in Mexico is unique owing to the strongly
   government-regulated market. Even after the liberalisation in the early
   1990s, most shrimp farms are still owned and controlled by locals or
   local co-ops ( ejidos).

   Social tensions have occurred due to changes in the wealth distribution
   within populations. The effects of this are mixed, though, and the
   problems are not unique to shrimp farming. Changes in the distribution
   of wealth tend to induce changes in the power structure within a
   community. In some cases, there is a widening gap between the general
   population and local élites who have easier access to credits,
   subsidies, and permits and thus are more likely to become shrimp
   farmers and benefit more. In Bangladesh, on the other hand, local
   élites were opposing shrimp farming, which was controlled largely by an
   urban élite. Land concentrations in a few hands has been recognized to
   carry an increased risk of social and economic problems developing,
   especially if the landowners are non-local.

   In general, it has been found that shrimp farming is accepted best and
   introduced most easily and with the greatest benefits for the local
   communities if the farms are owned by local people instead of by
   restricted remote élites or large companies because local owners have a
   direct interest in maintaining the environment and good relations with
   their neighbors, and because it avoids the formation of large-scale
   land property.

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