A shrimp farm is an aquaculture business that cultivates marine shrimp or prawns [1] for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to service the U.S., Japan and Western Europe. Global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9 billion U.S. dollars. About 75% of farmed shrimp is produced in Asia, in particular in China and Thailand. The other 25% comes mainly from Latin America, where Brazil is the largest producer. Thailand is the largest exporting nation.

Shrimp farming has grown from a traditional, small-scale businesses in Southeast Asia into a global industry. Technological advances have led to growing shrimp at ever higher densities. Broodstock is shipped worldwide. Virtually all farmed shrimp are penaeids (i.e., 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.

Contents

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1 History and geography 2 Farming methods

o 2.1 Life cycle o 2.2 Supply chain o 2.3 Hatcheries o 2.4 Nurseries o 2.5 Growout o 2.6 Feeding the shrimp

3 Farmed species 4 Diseases 5 Economy

o 5.1 Socioeconomic aspects o 5.2 Marketing

6 Ecological impacts 7 Social changes 8 See also 9 Footnotes 10 Notes 11 References 12 External links

History and geography

Indonesians and others have farmed shrimp for centuries, using traditional low-density methods. Indonesian brackish water ponds, called tambaks, can be traced back as far as the 15th century. They used small scale ponds for monoculture or polycultured 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.[1] Such cultures often were in coastal areas or on river banks. Mangrove areas were favored because of their abundant natural shrimp.[2] Wild juvenile shrimp were trapped in ponds and reared on naturally occurring organisms in the water until they reached the desired size for harvesting.

Industrial shrimp farming can be traced to the 1930s, when Japanese agrarians spawned and cultivated Kuruma shrimp (Penaeus japonicus) for the first time. By the 1960s, a small industry had developed in Japan.[3] Commercial shrimp farming began to grow rapidly in the late 1960s and early 1970s. Technological advances led to more intensive forms of farming, and growing market demand led to worldwide proliferation of shrimp farms, concentrated in tropical and subtropical regions. Growing consumer demand in the early 1980s coincided with faltering wild catches, creating a booming industry. Taiwan was an early adopter and a major producer in the 1980s; its production collapsed beginning in 1988 due to poor management practices and disease.[4] In Thailand, large-scale production expanded rapidly from 1985.[5] In South America, Ecuador pioneered shrimp farming, where it expanded dramatically from 1978.[6] Brazil had been active in shrimp farming since 1974, but trade boomed there only in the 1990s, making the country a major producer within a few years.[7] Today, there are marine shrimp farms in over fifty countries.

Farming methods

When shrimp farming emerged to satisfy demand that had surpassed the wild fisheries' capacity, the subsistence farming methods of old were rapidly replaced by the more productive practices required to serve a global market. Industrial farming at first followed traditional methods, with so-called "extensive" farms, compensating for low density with increased pond sizes; instead of ponds of just a few hectares, ponds of sizes up to 100 hectares (1.0 km2) were used and huge areas of mangroves were cleared in some areas. Technological advances made more intensive practices possible that increase yield per area, helping reduce pressure to convert more land. Semi-intensive and intensive farms appeared, where the shrimp were reared on artificial feeds and ponds were actively managed. Although many extensive farms remain, new farms typically are of the semi-intensive kind.

Until the mid-1980s, most farms were stocked with young wild animals, called 'postlarvae', typically caught locally. Postlarvae fishing became an important economic sector in many countries. To counteract the depletion of fishing grounds and to ensure a steady supply of young shrimp, the industry started breeding shrimp in hatcheries.

Life cycle

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 bodies, and then metamorphose into zoeae. Shrimp in this second larval stage feed in the wild on algae, and after a few days, morph again into myses. The myses 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 that have adult characteristics. The whole process takes about 12 days from hatching. In the wild, postlarvae then migrate into estuaries, which are rich in nutrients and low in salinity. They migrate back into open waters when they mature. Adult shrimp are benthic animals living primarily on the sea bottom.[8]

Supply chain

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 accelerate growth and maturation 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 grow postlarvae and accustom them 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, even three are possible. 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.[9]

Hatcheries

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.[3]

Nurseries

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.[10]

In a typical nursery, there are 150 to 200 animals per square meter. They are fed on a high-protein diet for at most 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 use 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.[3]

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.[11]

Growout

Shrimp pond with paddlewheel aerators in Indonesia. The pond is in an early stage of cultivation; plankton has been seeded and grown (whence the greenish color of the water); shrimp postlarvae are to be released next.

A one-horsepower paddlewheel aerator. The splashing may increase the evaporation rate of the water and thus increase the salinity of the pond.

The intake of a two-horsepower "turbo aerator", which paddles one meter below the water surface. To avoid stirring up pond sediments, the water depth should be at least 1.5 m.

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 meter, or 25,000/ha)[2]. 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.[12]

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/square meter (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 meter, aeration is often required to prevent oxygen depletion. Productivity varies 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 aerated, 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, and the rest are intensive farms. Regional variation is high, though, and [Tacon (2002)] reports wide discrepancies in the percentages claimed for individual countries by different studies.[12]

Feeding the shrimp

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 boost the growth of the phytoplankton to accelerate the growth of the shrimp. Waste from the artificial food pellets and shrimp excrement can lead to the eutrophication of the ponds.

Artificial 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 shrimp have eaten them.[3] They are fed two to five 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 (FCR), 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 1.2–2.0 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.[13]

Lower FCRs result in a higher profit for the farm.

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),[14] and within it to the genus Penaeus [3] . 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. L. 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.[15] Other species being bred are:

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 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.[16] 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.[17] 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.[18]

Whitespot syndrome is a disease caused by a family of related viruses. First reported in 1993 from Japanese P. japonicus cultures,[19] 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.[20]

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 L. vannamei there. Birds are thought to be a route of infection between farms within one region.[21]

Infectious hypodermal and hematopoietic necrosis (IHHN) is a disease that causes mass mortality among P. stylirostris (as high as 90%) and severe deformations in L. vannamei. It occurs in Pacific farmed and wild shrimp, but not in wild shrimp on the Atlantic coast of the Americas.[22]

There are also a number of bacterial infections that are lethal to shrimp. The most common is vibriosis, caused by bacteria of the Vibrio species. 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.[23] 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.[24]

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 disease outbreak in the first place. Active water quality management helps avoid poor pond conditions favorable 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.[25] 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.[6]

Economy

The total global production of farmed shrimp reached 2.5 million tonnes in 2005.[26] This accounts for 42% of the total shrimp production that year (farming and wild catches combined). The largest single market for shrimp is the United States, importing between 500 – 600,000 tonnes of shrimp products yearly in the years 2003-2009.[27] About 200,000 tonnes yearly are imported by Japan,[28][29] while the European Union imported in 2006 another about 500,000 tonnes of tropical shrimps, with the largest importers being Spain and France.[30] The EU also is a major importer of coldwater shrimp from catches, mainly common shrimp (Crangon crangon) and Pandalidae such as Pandalus borealis; in 2006, these imports accounted for about another 200,000 tonnes.[31]

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$8.00. The average import price in the EU was only about US$5.00/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.[32]

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.[33] 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.[34] 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.[6]

From top to bottom: pieces of the carapace of Litopenaeus vannamei; a harvested healthy L. vannamei of size 66 (17 g); a dead L. vannamei infected by the Taura syndrome virus (TSV). The color of healthy shrimp is determined by the color of the plankton, the type of soil at the pond bottom, and the additional nutrients used. The white color of the shrimp at the bottom is due to the TSV infection.

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.[35] In Ecuador alone, production suffered heavily in 1989 (IHHN), 1993 (Taura), and 1999 (whitespot).[36] 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.[2]

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,[37] or the "anti-dumping" case initiated by U.S. shrimp fishers in 2002 against shrimp farmers worldwide,[38] which resulted two years later in the U.S. imposing antidumping tariffs of the order of about 10% against many producer countries (except China, which received a 112% duty).[39] 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.[6] Furthermore, shrimp prices dropped sharply in 2000.[40] 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.[2][6]

Socioeconomic 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.[41] The published literature on that topic shows large discrepancies, and much of the available data are of anecdotal nature.[42] Estimates of the labor intensity of shrimp farms range from about one-third [43] to three times more[44] 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 labor per unit area than extensive farming. Extensive shrimp farms cover much more land area and are often, but not always, located in areas where no agricultural land uses are possible.[45] 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 employment. A global estimate from one study is that a shrimp farm worker can earn 1.5 – 3 times as much as in other

jobs;[46] a study from India arrived at a salary increase of about 1.6,[44] and a report from Mexico states the lowest paid job at shrimp farms was paid in 1996 at 1.22 times the average worker salary in the country.[47]

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 a farmer in Thailand could increase his income by a factor of ten by switching from growing rice to farming shrimp.[48] An Indian study from 2003 arrives at similar figures for shrimp farming in the East Godavari district in Andhra Pradesh.[49]

Whether the local population benefits from shrimp farming is also dependent on the availability of sufficiently trained people.[50] 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.[51] More intensive farms have a need for year-round labor in more sophisticated jobs.

Marketing

Main article: Shrimp marketing

For commercialization, shrimp are graded and marketed in different categories. From complete shrimp (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 shrimp attaining higher prices.

Ecological impacts

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 the Pacific Coast of Honduras between 1987 and 1999. The shrimp farms appear as rows of rectangles. In the older image (bottom), mangrove swamps stretch across the estuaries of several rivers; one shrimp farm is already visible in the upper left quadrant. By 1999 (top image), much of the region had been converted to blocks of shrimp ponds.

A toxic sludge oozing out of the bottom of a shrimp pond of a farm in Indonesia after the harvest. The liquid pictured here contained sulfuric acid resulting from oxidation of pyrite contained in the soil. Such contamination of a pond leads to stunted growth of the shrimp and increased mortality rates; the growth of the plankton is reduced drastically.[52] Liming can be applied to counteract to some extent the acidification of the water in ponds on acid sulfate soil,[53]

such as mangrove soils.[54]

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;[55] 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.[2] 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.[4] 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 for areas such as the Myanmar Coast mangroves.[2]

Intensive farms, while reducing the direct impact on the mangroves, have other problems. Their nutrient-rich effluents (industrial shrimp feeds disintegrate quickly, as little as 30% are actually eaten by the shrimp with a corresponding economic loss to the farmer, the rest is wasted[3]) are typically discharged into the environment, seriously upsetting the ecological balance. These waste waters contain significant amounts of chemical fertilizers, pesticides, and antibiotics that cause pollution of the environment. Furthermore, releasing antibiotics in such ways injects them into the food chain and increases the risks of bacteria becoming resistant against them.[56] However, most aquatic bacteria, unlike bacteria associated with terrestrial animals, are not zoonotic. Only a few disease transfers from animals to humans have been reported.[57]

Prolonged use of a pond can lead to an incremental buildup of a sludge at the pond's bottom from waste products and excrement.[58] The sludge can be removed mechanically, or dried and plowed to allow biodecomposition, at least in areas without acid problems. 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.[4] Thailand has banned inland shrimp farms since 1999 because they caused too much destruction of agricultural lands due to salination.[9] A Thai study estimated 60% of the shrimp farming area in Thailand was abandoned in the years 1989–1996.[5] Many of these problems stem from using mangrove land that has high natural pyrite content (acid sulfate soil) and poor drainage. The shift to semi-intensive farming requires higher elevations for drain harvesting and low sulfide (pyrite) content to prevent acid formation when the soils shift from anaerobic to aerobic conditions.

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 worldwide. As a consequence, most broodstock shipments require health certificates and/or to have specific pathogen free (SPF) status. Many organizations lobby actively for consumers to avoid buying farmed shrimp; some also advocate the development of more sustainable farming methods.[59] 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.[60] 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.[61]

Yet, the industry has been slowly changing since about 1999. It has adopted the "best management practices"[62] developed by the World Bank program, for example, and others.[63] and instituted educational programs to promote them.[64] Due to the mangrove protection laws enacted in many countries, new farms are usually of the semi-intensive kind, which are best constructed outside 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.[6] 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 program 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.[2] 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).[65] 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.[6] 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).[66]

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.[67] In Bangladesh, on the other hand, local élites were opposing shrimp farming, which was controlled largely by an urban élite.[68] 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.[67]

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.[69]

Main impacts of shrimp aquaculture

The key environmental and social issues related to shrimp aquaculture are:

Farm design: Ecologically-sensitive habitat, such as mangrove forests, can be cleared to create ponds for shrimp production

Water use/pollution: Salt water from shrimp farms can seep into the groundwater and onto agricultural land (a process called salinization); organic waste, harsh chemicals and antibiotics from shrimp farms can pollute the water; and aquifers can be drained to supply water to shrimp farms

Feed management: Wild stocks of fish can be depleted for use in formulated feeds for shrimp production

Broodstock: Biodiversity issues can arise from the collection of wild brood and seed Pathogens:The introduction of pathogens can lead to major shrimp disease outbreaks and

significant economic losses in producing countries Socioeconomic issues: Jobs can be eliminated when there are fewer wild caught shrimp to

harvest and/or shrimp farms are shut down due to disease outbreaks; public access to land can be restricted

Environmental impacts As with most development activities, including agriculture, shrimp farming is associated with a number of negative environmental impacts. These include habitat conversion; conversion of land from other valuable uses; nutrients and organic matter in effluent; chemicals used in soil, water, and disease treatment; salinization; and the introduction of non-native species or genetically distinct varieties. The causes of environmental impacts are multiple, although seldom present all at once: poor planning and management of water supply and effluent; poor siting; poor design and technology; poor management practices and lack of knowledge about potential environmental damage; high disease incidence and associated use of chemicals; insufficient legal frameworks and regulatory instruments; weak law enforcement; and the prospect of rapid, high profits. The profit potential may undermine long-term planning and far-sighted farm management, which can contribute to environmental conservation if allowed to govern decisions. It is extremely difficult to address most of these problems through conventional farm- or project-level environmental impact assessments (EIAs). Many shrimp farm developments, especially in Asia, are small scale, and their impact is insignificant when considered in isolation. However, very large numbers of such small-scale developments have serious cumulative environmental effects when concentrated in high densities in some locations. Therefore, project EIA is neither useful nor feasible for such developments,

and to date has had limited positive effect on the development of the sector. These cumulative impacts can be addressed only through sector environmental assessment (EA), undertaken for a specific estuarine, watershed, or coastal zone, which assesses the actual and potential impacts on the whole sector and seeks to mitigate adverse impacts through a range of planning, regulatory, economic, and infrastructure incentives and constraints. Ideally, such an EA would form part of a broader

regional EA covering other sectors and activities. It is possible to farm shrimp with minimal environmental impact. A wide range of practical measures for significantly reducing the potential damage from shrimp aquaculture, and making it more sustainable against a variety of criteria, are presented in Chapter 4. There is a pressing need for a strong set of incentives and constraints to promote implementation of these measures at farm level. Furthermore, some impacts can be reduced only through better siting and improved planning of the development of the whole sector in a defined area. All of these issues should be addressed in sector EA. The discussion of environmental impacts and mitigation measures in Chapter 3 provides a broad basis for the development of more detailed and practical guidelines for project- or farm-level environmental assessment. vi Social impacts Shrimp farming is one of very few options for economic development in poor coastal areas with saline soils, and has the potential to enormously enhance smallholder income, or to provide relatively well-paid employment at larger operations. Despite claims to the contrary, it appears that shrimp farming can create relatively high levels of employment per unit area of land when compared with most feasible alternatives. However, the risks associated with shrimp farming are considerable, and some extreme cases of negative social impacts have been reported. Some interest groups have shown a tendency to focus exclusively on these negative cases and have turned significant media attention on them. The result has been that the general public, as well as environmentally concerned groups, have the impression that shrimp farming represents a danger to the socioeconomic development of a country or region. Unfortunately, very few studies exist that have thoroughly and objectively assessed and presented the balance of social and environmental costs and benefits. Although shrimp farming has sometimes been associated with increased inequity, resource appropriation, and resource use conflict, it should be emphasized that these problems are related less to the nature of shrimp farming itself than to the social, economic, and political contexts in which it has developed. The financial attractiveness of shrimp farming has been exceptional, and this has exaggerated and drawn attention to what are common development problems. Shrimp farming has become the victim of its own success. Further studies are required to gain a better and more objective understanding of these issues. It is clear from the nature of the social impacts and related experiences that—just as with the environmental impacts—much more attention must be paid to proper planning. Social as well as environmental impact assessments should be undertaken for the sector as well as for individual projects. Practical measures for minimizing social impacts are presented in Chapter 4; these may serve as a basis for developing practical guidelines for social impact assessments at project and sector levels.

Abstract

The consumption of seafood, especially shrimp, increases yearly in the U.S. The U.S. is the second largest importer

of shrimp in the world, consuming more than 11% of the total world production. Aquaculture is becoming an

increasingly important source of the world's shrimp, currently accounting for approximately 30% of the world's supply.

Unfortunately, in this era of international trade deficits, U.S. production of aquacultured shrimp is insignificant (<

0.1%) compared with world production. As shrimp aquaculture expands in the U.S., so does the use of intensive

farming techniques. Shrimp aquaculture is like any other animal husbandry industry in that shrimp are subject to

disease, especially under intensive farming methods. In penaeid shrimp, the primary diseases associated with

mortalities are usually viral or bacterial. The majority of bacterial infections in penaeid shrimp are attributable to Vibrio

species, with mortalities ranging from insignificant to 100%. However, the rapid growth of this industry has outpaced

efforts by researchers, pharmaceutical companies, and federal regulatory agencies to provide approved

therapeutants for shrimp disease management. Approval of drugs and their surveillance for compliance with

regulations applicable to seafoods, including aquacultured goods, is the responsibility of the FDA. There are three

general areas of concern regarding human health when chemotherapeutants are used in aquaculture: (1) residues of

drugs in fish destined for human consumption; (2) development of drug resistance in human pathogenic bacteria; and

(3) direct toxic effects to humans from handling of drugs. Currently, there are no antibacterials approved for shrimp

aquaculture in the U.S. One of the major obstacles in the development and approval of new drugs for aquaculture is

the cost of conducting the required studies. The high cost to pharmaceutical companies discourages investment in

shrimp chemotherapeutant research, since the current U.S. market for such products is small. Unfortunately, the U.S.

shrimp aquaculture industry will remain small without legal availability of chemotherapeutants. Oxytetracycline (OTC)

and Romet-30 are two antibacterials currently approved in the U.S. for catfish and salmonid aquaculture. Shrimp

aquaculture facilities outside of the U.S. routinely use these drugs, as well as others, in the treatment of bacterial

disease outbreaks. Much of the work required for OTC approval by the FDA for penaeid shrimp has been completed.

(ABSTRACT TRUNCATED AT 400 WORDS)

Shrimp farming in Latin America: Current status, opportunities, challenges and strategies for sustainable development  Authors: Carlos G. Wurmanna; Raul M. Madridb; Andre M. Bruggerc

Abstract

Shrimp farming in Latin America and the Caribbean (hereinafter, LA&C) is a complex, diverse and dynamic activity, occurring in 22 out of 36 countries, producing 231,000 tons, valued at US$ 1.2 billion in 20021. Farmed shrimp represents 52% of all shrimp volumes produced regionally, and almost 18% of all shrimp and prawn (S&P, hereinafter) cultivated worldwide. Whiteleg shrimp (Litopenaeus vannamei) constitutes 91% of all shrimp farmed in LA&C and five nations, led by Brazil -formerly by Ecuador-, comprise 82% of farmed production. Over 90% of LA&C shrimp production is exported (230,000 tons of end products from both aquaculture and wild origin valued at US$ 1.36 billion), generating a trade surplus of US$ 1.28 billion (2002).

Farmed shrimp could easily surpass 513,000 tons by 2030, more than doubling current regional figures (2.9% annual growth rate, compounded). However, competition with Asian countries,

anti-dumping accusations and other factors might limit the expansion process, which is increasingly determined by strategically important matters rather than by physical production constraints. Here, a 'production-driven' process of past decades is being replaced by a 'demand-led' situation, where market and marketing issues will increasingly influence the outcome of shrimp farming.

Growing market competition will continue to press prices down and industry will be forced into a permanent process to improve competitiveness. Here, development strategies include actions by governments and producer associations, promotional and marketing campaigns and the application of good management practices across the production and distribution chains. Keywords: shrimp farming; aquaculture; aquaculture development; aquaculture in Latin America; Latin America and the Caribbean; sustainable aquaculture

    

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Chapter 4. Backyard hatcheries and small-scale shrimp and prawn farming in Thailand

Document(s) 8 of 15 Hassanai Kongkeo and F. Brian Davy

Abstract Thailand has continued to retain the global dominance in shrimp production for over a decade in spite of many adversaries, providing a source of major income, foreign exchange generation, and livelihood opportunities. The Thai shrimp farming sector essentially consists of small scale owner-managed and operated practices, with an average farm size of 1.6 ha. The farming

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systems have been resilient and adaptive, which has been a key to their sustainability. One of the keys to continued success has been the emergence of backyard hatcheries that provide reliable quality seed stock to the industry. The government support to these hatcheries in the early stages, together with the effective dissemination of culture technologies through the initiatives of the farmers themselves at all stages of the cycle, has facilitated and enabled the farmers to be on a firm footing and encouraged them to embrace changes, and make it sustainable. All these factors together have made the Thai shrimp farming sector a success, while the sector in many of the neighboring countries became almost complete disreputable.

4.1 Historical Development of Backyard Hatcheries

Backyard hatcheries refer to small scale usually family-owned and operated seed production operations that were most often located in the backyard of the owners; hence, the choice of this name (see Plate 4.1).

This close proximity to the family home was critical as it provided family labor, and almost round the clock vigilance, which were the key reasons for success. The development of these hatcheries was closely tied to the overall development of marine shrimp and the giant freshwater prawn, Macrobrachium, as well as other cultured marine finfish species, a point that will be dealt with later in this case study.

H. Kongkeo( ) and F.B. DavyNetwests of Aquaculture Centres in Asia-Pacific, PO Box 1040, Kasetsart Post Office,Bargkok 10903, Thailande-mail: Hassanai.kongkeo@enaca.org

S.S. De Silva and F.B. Davy (eds.), Success Stories in Asian Aquaculture, 67

© Springer Science+Business Media B.V. 2009

Plate 4.1 Backyard hatchery

These backyard hatcheries were first developed as part of the major extension thrust in a Thai Department of Fisheries (DOF) – FAO freshwater prawn project that started in 1974. This project was developing technical know-how, but ended up providing free Macrobrachium rosenbergii postlarvae (PLs or seed) for stocking for the initial grow-out operations in neighboring farms. Large quantities of PLs were produced at the fisheries station in Bangpakong District, Chacheongsao Province, and distributed by road and rail all over Thailand. However, more interestingly, many of the technical staff of the Bangpakong station also began to produce PLs at their nearby homes, adapting the technology to less conventional smaller holding containers locally used for storing drinking water. Before long, many of the stilted houses of the staff and their friends and neighbors had small production units underneath their living quarters. Even nonscientific staff learned the necessary techniques quickly and then this technology was transferred from DOF technical staff directly to interested farmers. Soon, the first “commercial backyard hatcheries” began to spring up in nearby areas all around Chacheongsao Province. This new approach followed the principle of traditional backyard

kitchen garden and fish pond operations, and developed in direct contrast to the massive species-specific concrete fixed structure hatcheries that were set up elsewhere in the 1970s and 1980s. These simple backyard hatcheries were later easily and cheaply modified to produce marine shrimp PLs (Penaeus monodon, P. vannamei), grouper (Epinephalus spp.) and seabass (Lates calcarifer) fingerlings, and other marine finfish species.

This backyard hatchery concept was revolutionary in terms of the low initial investment on land, physical facility construction, and limited need for large scale costly equipment; also the operation costs were relatively low because of the simple techniques and small scale of the operation. These innovations demonstrated the resourcefulness of small farmers and their abilities to take ideas for development and modify them to suit the local conditions. Farmers were eager to experiment and continue learning from their own mistakes. For instance, the use of hypersaline water from coastal salt farms was found to be more cost effective when transported by truck and subsequently diluted to the desired salinity with disinfected freshwater. More importantly, this hypersaline water is pathogen-free (i.e. virus free). The business is organized with these hatcheries purchasing P. monodon or P. vannamei nauplii from nauplii producers who are located near the open sea areas (better water quality and circulation assist in the maturation process). For Macrobrachium, hatchery operators use spawners both from grow-out farms and from the wild. The present success of Thailand in shrimp and prawn industry is testimony to the persistence and ingenuity of Thai farmers in utilizing applied science to its utmost potential.

As mentioned earlier, small hatcheries run by family owner-operators are usually more

efficient than larger scale hatcheries, which are operated using hired labor. This family manpower is more flexible with mainly family members, such as the husband, wife or children assisting as needed after school hours. Backyard hatcheries originally started as a secondary occupation for rice farmers or fishers, but soon these activities yielded more income than the primary occupation. The decrease in price of shrimp fry caused by the spread of these backyard hatcheries also helped to stimulate the rapid expansion of grow-out ponds. This family business approach contrasts sharply with the large scale high capital cost hatcheries in which the high fixed costs of wages, power supply, supporting facilities, and other overheads made closure, even for relatively short periods, very difficult.

Backyard hatcheries, in contrast, could discontinue production when disease or other serious problems occurred, even for relatively long periods, without undue hardship when small scale farmers could switch back to their primary occupations of rice farming or fishing. It turned out that periodic discontinuation of the backyard operations was, in fact, useful in checking disease by facilitating the reconditioning, drying, and disinfection of tanks, ponds, aeration, and water systems. These concepts are summarized in the Farm Performance Survey (ADB/NACA 1997), in which Thai small-scale operations yielded more benefits than medium and large scale operations in Indonesia, Taiwan, and Philippines, respectively (Table 4.1).

To complement the backyard hatcheries operations, a variety of ancillary locally developed farm equipment and supply operators developed as well (such as aerators or paddle wheels, water pumps, harvesting sets, commercial larval and adult feeds, probiotic products, and miscellaneous farm supplies). Associated with this was the development of a

variety of ancillary businesses such as broodstock suppliers, nauplii producers, PLs distribution, pond preparation, PCR (a disease diagnosis tool) and water quality testing services, harvesting, pond construction, and supply of heavy machines for pond construction. These ancillary businesses developed as different operators identified new entry points in the previously large scale operations.

Table 4.1 Annual financial performance in 1 ha intensive pond (in US$; adopted from Kongkeo, 1997)

ParameterIndonesia

Philippines Taiwan Thailand

Average farm size (ha)

5 9 3 2

Average scale of operation

Medium Large Medium Small

Stocking (PL/m2) 78 38 73 114

Yield (ton) 6.06 3.05 2.88 10.49

Shrimp sale/kg 6.5 7.1 12.46 6.94

Total shrimp sales 39,390 21,655 35.885 72,801

Labor/kg (% of total)

0.20 0.43 0.20 0.19

(5.7) (6.3) (2.8) (4.4)

Feed/kg (% of total)

1.41 2.62 1.65 2.01

(39.9) (38.4) (22.6) (47.1)

Seed/kg (% of total)

0.58 1.27 0.87 0.59

(16.4) (18.6) (11.9) (13.8)

Power/kg (% of total)

0.36 0.29 0.67 0.33

(10.3) (4.2) (9.1) (7.8)

Other/kg (% of total)

0.18 0.08 0.58 0.26

(5.1) (1.1) (8.0) (6.2)

Overhead/kg (% of total)

0.13 0.00 0.68 0.37

(3.7) (0.1) (9.4) (8.6)

Depreciation/kg (% of total)

0.67 2.14 2.64 0.52

(18.9) (31.3) (36.2) (12.1)

Production costs/kg (total)

3.53 (21,370)

6.83 (20,820)

7.29 (20,990)

4.27 (44,870)

Net profit margin/kg (total)

2.97 (18,030)

0.27 (880) 5.17 (14,910)

2.67 (27,930)

The risks in these ancillary businesses are also reduced due to shorter periods of operation and the specialized expertise in each business. In addition to the socioeconomic benefits to these small-scale operators, local communities were shown to have less social conflicts within their own communities, unlike the experiences of larger scale investments in South America and elsewhere. This is similar to the success of small-scale intensive grow out ponds, which spread all over the country (more than 80% of Thai marine shrimp production came from approximately 12,500 intensive farms in which small farmers typically operate 1–2 ponds with average farm size of 1.6 ha and a total production area of 27,000 ha, Kongkeo 1995, 1997). However, it is recognized that large scale operators are usually important to pioneer development and adaptation of new technologies from government or overseas operations. After being developed in Thailand, the backyard hatchery technology has been transferred through assistance of FAO, Network of Aquaculture Centres in Asia-Pacific (NACA), UNDP, Royal Thai government, and the private sector to Indonesia, Vietnam, India, Bangladesh, and Myanmar. These transfers were then locally adapted, for instance, in some countries, direct seawater was used because they have better

seawater supply sources.

4.2 Present Status of Backyard Hatcheries in Thailand

There are more than 2,000 small scale hatcheries in Thailand, mainly located in Chacheongsao, Chonburi, and Phuket provinces, with a total production of more than 80 billion marine shrimp PLs per year (approximately 90% of the total production). Despite their survival over many crises in the past 20 years, these operators recently suffered from disease-related competition with specific pathogen free (SPF) PLs supplied by large scale hatcheries. Such hatcheries can utilize high cost technologies such as SPF and disease resistant strains, bio-secure systems, raceways, etc. taken from overseas. To cover their high investment costs, these large scale hatcheries are under pressure to increase their margin by selling PLs directly to grow out farms, instead of selling nauplii to backyard hatcheries as they had formerly done. After lengthy negotiations, the regulations were then relaxed by releasing SPF nauplii to some backyard hatcheries, which are able to adapt this technology to their present business conditions in 2008. It is expected that the backyard hatchery operators will continue to adapt the SPF concept, but the new world economic crisis caused by US economic slump has led the Thai shrimp industry to reduce its production by 30% in 2008. On the other hand, the Thai shrimp industry is also reducing its dependence on export income through an increase in local consumption, which has reached nearly 35% of the production.

Other new challenges are developing. Traceability of broodstock and certification requirements of developed countries are also difficult problems for these backyard hatcheries because they purchase nauplii from external suppliers. Although nauplii producers can issue PCR negative certificates, it is difficult for them to sort out the source of shrimp (P. monodon)

by particular backyard hatcheries. Distributors usually mix nauplii from various sources for easy distribution and economic reasons.

The Thai DOF has tried very hard to assist small scale operators. A farm registration system and code of conduct (CoC) and good aquaculture practice (GAP) certification systems have been implemented since 2003. At the moment, 98 hatcheries and 727 backyard hatcheries have been certified with CoC and GAP standards, respectively. Furthermore, the use of the “Movement Document” and traceability system at the grow-out farm level has been recently implemented and is expected to be functioning properly to cover the hatcheries in the next few years.

4.3 History of Freshwater Prawn Farming

As mentioned above, backyard hatcheries grew in relation to freshwater prawn and shrimp farming and it is important to understand their evolution. Besides, both prawn and shrimp farming are dominated by small scale operators and illus trate the related successes of the backyard hatcheries (Kongkeo and New 2008). One of the important milestones in freshwater prawn farming occurred in the late 1970s when the United Nations Development Program decided to fund a 3-year FAO-executed project, “Expansion of Freshwater Prawn Farming,” in Thailand (New 2000). As a result of these efforts, farmed freshwater prawn production expanded from less than 5 tons/year before the project began (1976) to an estimated 400 tons by the time it ended in 1981 (Boonyaratpalin and Vorasayan 1983). Soon afterwards (1984), the DOF reported to FAO that Thai production had exceeded 3,000 tons/year (FAO 1989), a very rapid expansion indeed.

This DOF-FAO project not only enabled the establishment of a significant aquaculture sector in Thailand, but also facilitated the

development of freshwater prawn farming globally. This facilitation included steps such as the publication of a technical manual on the topic (New and Singholka 1985; New 2002) that was translated into many languages. In addition, the Thai DOF hosted “Giant Prawn 1980,” the first international aquaculture conference ever held in Thailand (New 1982). Many Thai experts later advised Macrobrachium projects and ventures elsewhere in Asia. By 2005, the aquaculture production of M. rosenbergii in Thailand had risen to 30,000 tons/year (valued at US $79 million) and to more than 205,000 tons/year globally (FAO 2007).

Though there has been a great potential for expansion of farming areas and yield, Thailand has maintained production at this level, despite the lack of export markets, unlike for marine shrimp. Similar to mud crab, Macrobrachium has a thick shell and a big carapace; when frozen with its shell-on or head-on, it is not well accepted in the international market. Also, it deteriorates after defrosting or refreezing and has a small meat to body weight ratio making it uneconomic for export in the form of frozen peeled prawn. In fact, the head is the most delicious part of prawn for Asian dishes. However, prices in domestic markets are more stable than marine shrimp, which mainly relies on export markets. Similar to the export market of marine shrimp, the domestic market of freshwater prawn was enlarged by reducing the selling price (Fig. 4.1). Farmers also practice partial harvest for the live prawn market to yield better prices. This partial harvest could reduce biomass density, thereby improving the growth of the remaining prawns and reducing the risk of a long culture period. Though there were the serious problems in terms of deteriorated broodstock and Nodavirus outbreak in 2005, farmers could recover in the next year due to their skills in pond management and their efficient scale of

operation (Fig. 4.1). In addition, a similar quantity of a related species, M. nipponense, was produced in China in 2007. In total, the global farm-gate value of freshwater prawn farming had reached almost US $1.84 billion/year by 2007.

4.4 History of Marine Shrimp Farming

At the beginning, extensive culture of banana shrimp (P. merguiensis) and greasy shrimp (Metapenaeus spp.) using wild seed stocks were practiced over the past 60 years. Though there was no seawater available, the Bangkok Marine Laboratory successfully cultured to PLs stage P. merguiensis, P. semisulcatus, P. latissulcatus, M. monoceros and M. intermedius in 1972 (Cook 1973). Seawater had to be brought from offshore by boat. All gravid female shrimp were captured in the Gulf of Thailand. Experiments on pond culture of artificially bred seed were carried out at private shrimp farms in Samutsakorn Province and Bangpoo, Samutprakarn Province, but the results were not satisfactory.

Fig. 4.1 Giant freshwater prawn (Macrobrachium rosenbergii) production and average farm gate prices in Thailand (FAO Fishstat Plus)

In 1973, the Phuket Coastal Fisheries Research and Development Centre (former Phuket Marine

Fisheries Station) successfully bred P. monodon by induced spawning from broodstock caught from Andaman Sea. PLs of the early batches were stocked in semi-intensive ponds in Bangkrachai, Chantaburi Province, Klongdaan, Samutprakarn Province, and Klongsahakorn, Samutsakorn Province in 1974. This brought shrimp farming the much needed technique that enabled the farmers to have better control of their crop and sustainable production, instead of reliance only on wild seed for stocking in an extensive culture system. This important research later led to the highest peak of P. monodon production of 304,988 m in 2000 (Kongkeo 2006) before substitution by P. vannamei and the increased demand for the backyard hatcheries.

Though commercial semi-intensive culture of P. monodon using hatchery produced fry commenced in 1974, it expanded rather slowly compared to Taiwan due to the lack of suitable feed, low demand in the internal market (only US $2.50–3.20/kg), and suitable farming practices. Prior to 1985, Taiwan was the only supplier to the Japanese shrimp market due to the cheaper cost of transportation. However, Japan had to stock Taiwanese shrimp in their cold storages for whole year-round consumption. After 1985, the labor and electricity costs went up very significantly due to the Japanese economic boom. Japanese cold storages could no longer bear the heavy increase in operational costs if shrimp had to be stored for long periods (2–10 months in a year). As a temperate country, Taiwan could produce only one crop per year and export to Japan only during a few months of the year before winter. Therefore, Japan had to urge tropical countries, like Thailand and the Philippines, to produce P. monodon for a continuous supply throughout the year to save on cold storage costs. Thus, Japan increased the buying price of shrimp from tropical countries to US $8.00–10.00, in order to encourage the expansion of shrimp farming.

This brought heavy profits to farmers and leading to the first boom of P. monodon intensive culture in the country. In 1987–1988, the collapse of the shrimp industry in Taiwan led to further increases in shrimp production in Thailand.

Similarly in 1993, P. chinensis shrimp crops collapsed, probably due to Whitespot viral disease in China; Thailand was able to rapidly increase production to more than 200,000 t to make up for the shortfall in the world supply. The sharp increase in shrimp prices in 1993 (Fig. 4.2) was driven mainly by the high demand in the global market, again spurring shrimp farmers to boost their production.

The outbreak of Yellow-head virus disease in Thailand starting in 1990 did not lower overall production (Fig. 4.2) due to good management practices and efficient small scale operations. Whitespot disease outbreak slightly affected the production during 1994–1997, before launching again in 1998, because the technologies on intensive closed system and on-screening of broodstock and PLs by PCR test were well adapted by farmers. These technologies were simplified and locally adapted to suit local conditions and farmer capabilities.

Similarly in 1993, P. chinensis shrimp crops collapsed, probably due to whitespot viral infection. In 1999, the Thai Government issued a decree to ban P. monodon farming in inland areas to avoid the negative environmental impact from saline water, which was not fully enforced until 2001 (Fig. 4.2).

Consequently, 30% of the total shrimp farming area that was located in freshwater areas of the country was affected by this decree. Farmers could not revert back to Macrobrachium culture, which yielded a very low price and had a limited market. Therefore, SPF P. vannamei from Hawaii was first introduced by the private sector in late

1999 for trials to replace P. monodon in freshwater areas. In fact, research has been conducted successfully in China to culture P. vannamei in freshwater areas without any introduction of saline water. After successful trials in Nakorn Pathom farms, it spread throughout all inland shrimp farming areas within 2 years. However, culture in pure freshwater yielded only small shrimp (15–20 g) and mortality occurred after 3 months. Because of the small size, farm gate price was low at the beginning of this development (Fig. 4.3), but this was compensated by increasing the number of crops, for example, to 3/year. When P. vannamei culture expanded into coastal areas beginning in 2003, production increased sharply. Prawn size and farm gate price also increased up to 20–30 g and US $3.0—4.0/kg, respectively, because saline water prolongs the culture period to 3.5—4.5 months.

Fig. 4.2 Giant tiger prawn (P monodon) production and farm gate price in Thailand (FAO Fishstat Plus and CP Shrimp Culture Newsletter)

Fig. 4.3 Pacific white shrimp (P vannamei) production and average farm gate price in Thailand (FAO Fishstat Plus and CP Shrimp Culture Newsletter)

Similar to P. monodon, an outbreak of Taura syndrome virus in P. vannamei began in 2004, but it did not lower the overall annual production (Fig. 4.3) as locally produced SPF PLs were commonly used for stocking. Government and the Thai Shrimp Farmers Association also promoted domestic consumption (as now more than 30% of total production) to avoid export price drops, which resulted from oversupply.

Thailand has been able to keep its position as a world leader in shrimp exports since 1988 (FAO Fishstat) due to its constant supply of raw material and efficient processing facilities. In order to expand export volume, the exporters had to reduce the shrimp price as much as possible to compete with other producers. Lowering the selling price also resulted in drawing in more customers in both export and domestic markets. Fortunately Thai shrimp farmers were able to reduce production costs by using small-scale operations and shifting to low cost species like P. vannamei, while maintaining high standards and quality of their products. Sharp increases in the volume of shrimp exports

during 2002–2007 were mainly caused by reductions in shrimp price to increase shrimp consumption (Fig. 4.4). This trend mirror imaged the trends of the past with commodities such as salmon and chicken.

Fig. 4.4 Thai shrimp export volume, value and FOB price (Royal Thai Department of Customs)

4.5 Key Factors for the Success of Small Scale Operators

In fact, the success of backyard hatcheries and small scale shrimp/prawn farmers more generally must be seen as part of a dynamic process involving continual adaptation to solve new problems. To be the leader in global shrimp production is not easy, but to keep this position for more than 20 years is even more difficult. These small scale farmers played a very significant role in maintaining this coveted status. They were able to survive during crises through which large scale operators could not. The key factors for their success include the following.

4.5.1 Key People and Organizations

Farmers always have new ideas for development or modification, and are eager to experiment on their own. This is similar to the success of fruit, rice, and orchid farming in

Thailand. Due to the long experience in aquaculture, particularly freshwater species and extensive marine shrimp farming, Thai farmers are able to cope very well with advanced technologies. Shrimp culture technology was mainly transferred among farmers from lead farmers who were the more innovative initial risk takers. It has been proven that shrimp culture technologies were rapidly transferred by observation and enthusiastic learning mostly from more experienced farmers, than through the government extension services. For instance, DOF budget for information and training is only 7.2% of total DOF budget (Table 4.2) or 0.38% of total shrimp ex-farm value, or 0.30% of total export value.

Nevertheless, government has an important role in areas, such as in research and development, regulating the industry, improving infrastructure (e.g. water sources), as well as providing many free services (disease diagnosis, diatom stocks, water and soil analyses, shrimp consultancy, and market advice). DOF Quality Control Section has a larger budgetary allocation (32%) and plays a very significant role in improving the seafood quality (international food safety standards and requirements from individual importing countries). Not only the DOF, but also the Ministry of Commerce, assists the shrimp industry in the promotion of shrimp products in domestic and international markets, improving the image of shrimp culture in international forums and negotiating trade barrier issues with importing countries. Universities and vocational colleges also assist in capacity building of resource persons for the shrimp farming industry. Many skilled farmers, who became leaders of farmer groups, were later trained and received further education in aquaculture. Many universities also conduct high quality research on P. vannamei and Macrobrachium farming in Kasetsart University, domestication of P. monodon and PCR in Mahidol University, shrimp

genetic and recycling pond in Burapa University, and treatment of farm effluent and sludge in Prince of Songkhla University.

Table 4.2 Budgetary allocations of the Thai Department of Fisheries (DOF) 2008

Item US $ %

Research and development

15,332,024 18

Information and training

6,155,827 7.2

Rural aquaculture 4,935,960 5.8

Quality control 26,926,481 31.7

Fisheries control 8,721,464 10.3

Stock enhancement and resource improvement

22,602,196 26.6

Other 305,411 0.4

Total 84,979,363 100

Feed factories also play important roles in shrimp extension programs through their sales services, including provision of regular training programs at their training centers through the support of overseas training for selected farmers.

4.6 Government Policy and Support

As Thailand is an agricultural country, government has had a major policy to promote crop production as “the world kitchen” and fully aims for development to assist the poor small scale operator. These policies directly benefit over 30,000 families of small scale farms, over 2,000 backyard hatchery families, and also many thousands of laborers in 184 shrimp processing plants, 49 canneries, and over 10 shrimp feed mills (DOF 2007). Good infrastructure facilities, such as roads,

electricity and water, were critically important initial facilities provided to these areas. Free technical assistance through DOF is the main policy that assists small scale farmers. DOF policies for disease prevention also permitted and strictly regulated only the SPF P. vannamei from Hawaii to enter the country. This partial relaxation on the import of certified, SPF PLs from Hawaii prevented the private sector and other interested parties from importing PLs from elsewhere (which could have been viral contaminated, thereby leading to serious impacts on the industry in Thailand in a major way). As mentioned earlier, the Ministry of Commerce, in cooperation with DOF, heavily promoted sales in both domestic and international markets. Price stabilization policies also helped small scale farmers to sell their products with guaranteed prices offered through the Agricultural Bank. The Agricultural Bank usually provides loans with minimal interest rate only to small scale farmers. Government also provided income tax exemption schemes to small scale farmers and fishermen if their net profits do not reach the ceiling.

4.6.1 Networking and Information Exchange

Networking and Information exchange have been very important mechanisms for farmers to avoid/reduce their losses from disease outbreak, drops in market price, increase in feed and seed prices, poor weather condition, etc. Information on new initiatives or shrimp farming products, alternate species, and advanced technology also help farmers to improve their profits. Such information will support them to make judgments regarding shifting cultured species, farming practices, or temporary discontinuation of production.

At the village level, farmers generally exchange their ideas on new initiatives, market information, disease outbreaks and aquaculture

news with neighboring farms through visits and/or via mobile phone. Farms are always open for visitors who need information even without any appointment. In some villages, they also have established shrimp farmer clubs as a forum for regular meetings to exchange ideas and information, as well as to increase the bargaining power with shrimp buyers/collectors. These farmers’ clubs were also established at district and provincial levels for the same purposes. At national level, shrimp farming associations and shrimp industry association (farms, feed plants, processing plants, and exporters) were established mainly for policy making and planning for shrimp culture development, information exchange, coordinating with government or outsiders, harmonizing trade conflicts, and bargaining with importers. In addition, information is exchanged at the regional or international level through regional organizations, such as the NACA, South East Asian Fisheries Development Centre (SEAFDEC), INFOFISH, shrimp website, international/regional magazines, and conferences.

Farmers also receive information on shrimp markets and new technologies from newsletters/publications from major shrimp feed producers, the national shrimp farming association, local shrimp farmer club, DOF magazine, over ten local aquaculture magazines, as well as the internet. Such information is also exchanged during meetings or conferences regularly organized by national associations, local farmer clubs, universities, DOF, feed producers, processing plants, and the direct communication with shrimp buyers/collectors and processing plants.

4.6.2 Crisis as One Key Driver of Success

As described above, there have been a number of crises (mainly diseases and market changes), which have acted as barriers to the success, but

more importantly served as key drivers for innovations by small scale operators. These crises included:

Yellow-head disease outbreak in P. monodon beginning in 1990

Whitespot disease outbreak in P. monodon starting in 1994

Devaluation of the Thai currency (Baht) in 1997, which caused significantly price increases in imported artemia, artificial plankton, chemicals and drugs, oil, etc.

Government ban on P. monodon farming in inland areas in 1990, which made farmers switch to P. vannamei culture

Strict application of EU regulations on zero tolerance for antibiotic residues in 2001

Taura syndrome outbreak in P. vannamei beginning in 2004

Tsunami disaster which damaged many hatcheries and broodstock centers in the south in late 2004

Limited distribution of SPF nauplii from major commercial SPF broodstock centers to backyard hatcheries in 2007

Traceability and certification requirements by importing countries in 2007

Global economic downturn caused by US economy and increase in oil price in 2008

4.7 Switching of Crustacean Species and Sustainable Farming

P. vannamei is not native to Asia (Fig. 4.5) and was first introduced to Taiwan in early 1990s to replace the problematic species, P. monodon. It was later transferred to China, Thailand, and Indonesia in early 2000s. Asia accounts for 85% of P. van-namei global production in comparison

to its native countries in Eastern Pacific (15%). Though it has been introduced for culture on the Atlantic side of Central and South America, Tahiti, Hawaii, and Taiwan nearly 20 years back, it is not significantly observed in the wild. This may be due to its poor mating habit, which is the major problem in hatchery production.

Fig. 4.5 Geographic distribution of native shrimp species, P. monodon and P. vannamei (Holthuis 1980)

In principle, for culture of any crop, farmers should have alternate species for their sustainable production, livelihoods, and profits. They should have a wider range of species for selection when the existing species encounters problems such as market, diseases, environment, etc.

Increases in P. vannamei production in Asia are mainly due to:

Shifting from problematic species, P. monodon in Southeast Asia and Taiwan as well as P. chinensis in China

Its ability to be domesticated and use as SPF broodstock compared to P. monodon;

Less virulent diseases

Tolerance to wider ranges of salinity and temperature

Better survival in poor pond bottom condition according to its schooling habit

Simple hatchery and grow-out technologies

Lower production costs, particularly seed, feed, water exchange, and aeration

In fact, reduction in the use of wild P. monodon broodstock may improve its health and enable a rebuilding of the wild population for future aquaculture use.

During its development in Asia, the industry had to solve the problems of price drops in international markets mainly due to oversupply. Thus, both Chinese and Thai industries launched heavy promotion for domestic consumption and intraregional trade. As a result, domestic consumption in China and Thailand reached 90% and 30%, respectively, in 2005. They also reduced the cost of production by using lower protein diet, higher stocking density, less water exchange, etc.

New diseases such as Taura syndrome, Infectious Hypodermal and Hematopoietic Necrosis (IHHN) were also introduced to the region. Thai farmers learned from the more virulent white spot and yellow head diseases of P. monodon how to solve the problems from these new diseases. For instance, SPF PLs from locally adapted broodstock are commonly used by farmers. Closed system small ponds (<1.0 ha) were another simple innovation to reduce stress by starting with an initial low salinity environment.

There are still many constraints that need to be solved by shrimp industry for their sustainability in the future such as:

Increasing costs of aeration, water pumping, and transportation

Declining demand: less consumption of seafood (as a luxury commodity) following the world economic crisis

Climate change is bringing a variety of

impacts (warmer surface water, increased frequency and intensity of storms, flood and cold bottom currents affecting wild broodstock)

Drops in supply of high protein fishmeal

New disease outbreaks leading to long-term sustainability of farms;

More export competition if the rapid growth of Chinese economy slows leading to oversupply to the domestic market

Under threat in key export markets due to adverse publicity concerning environmental impact such as mangrove, saline intrusion, etc.

Increasingly stringent international rules and agreements, such as

o Food safety and trans-boundary movement

o Eco-labeling and traceabilityo Biodiversity concerns regarding the

introduction of exotic specieso Trade barriers and specific rules

(e.g. GSP in EU, antidumping and C-bond in USA, GMOs in soybean, child labor, human trade, animal welfare, other social parameters, etc.)

Table 4.3 Shrimp production from CP Royal Shrimp-cum-rice Project, Prachinburi

ParameterP. monodon

P. vannamei

Salinity (ppt)

2–10 2–10

Density (PL/m2)

27 60

Culture period

135 120

(days)

Survival rate (%)

72 83

Harvest size (g)

26.3 16.6

Production (kg/ha)

5,117 8,281

In general, the international environment is continuing to present new challenges with the increasing international rules for the Asian shrimp industry. Small farmer operations face a variety of challenges here, many of which may only be solved by stronger networking and social organization. In early 2008, rice prices increased dramatically due to the global shortage of food and conversion of food crops to energy crops. Therefore, many Macrobrachium and P. vannamei farmers in freshwater areas in Thailand converted to the more profitable rice farming in their ponds. Organic load left from previous shrimp crops provided fertilizer for rice cultivation saving inorganic fertilizer costs. Similarly, many marine shrimp farms in brackish water areas also converted their ponds to rice production in the rainy season and switched back to shrimp production in the dry season. Before rice planting, farmers wash the surface of the pond bottom with freshwater to remove precipitated salt. Periodical discontinuation of shrimp production and replacement by rice cultivation will also break shrimp disease cycles and improve the quality of the deteriorated pond bottom (see the average results of 15 shrimp crops in Table 4.3).

References

ADB/NACA. 1997. Shrimp and carp aquaculture sustainability. Proceedings of Regional Study and Workshop on Aquaculture Sustainability and the Environment, Beijing, China, October 1995. Bangkok, Thailand: NACA.

Boonyaratpalin, M., and P. Vorasayan. 1983.

Brief note on the state of the art of Macrobrachium culture in Thailand. NACA Working Paper WP/83/7. Bangkok, Thailand: NACA.

Cook, H.L. 1973. FAO Report to the Government of Thailand on Shrimp Farm Development. FAO Report No TA 314. Rome: FAO.

DOF. 2007. Fisheries Statistics of Thailand, Department of Fisheries Circular No. 6/2007, Bangkok.

FAO. 1989. Aquaculture Production 1984–1986. FAO Fisheries Circular, 815. Rome: FAO.

Holthuis, L.B. 1980. Shrimps and Prawns of the World. An Annotated Catalogue of Species of Interest to Fisheries. FAO Fisheries Synopsis No. 125, FAO Catalogue vol. 1.

Kongkeo, H. 1995. How Thailand made it to the top. INFOFISH International 1/95: 25–31.

Kongkeo, H. 1997. Comparison of intensive shrimp farming systems. Aquaculture Research 28: 789–796.

Kongkeo, H. 2006. Responsible shrimpfarming: A critical overview. Presentation in WAS’06 Conference, Florence, Italy.

Kongkeo, H. and M.B. New. 2008. The successful development of backyard hatcheries for crustaceans in Thailand. Aquaculture Asia 13(1): 8–11.

New, M.B. ed. 1982. Giant Prawn Farming. Developments in Aquaculture and Fisheries Science, 10. Amsterdam, The Netherlands: Elsevier.

New, M.B. 2000. History and global status of freshwater prawn farming. In Freshwater prawn culture, ed. M.B. New and W.C. Valenti, 1–11.

Oxford: Blackwell Science.

New, M.B. 2002. Farming freshwater prawns: A manual for the culture of the giant river prawn (Macrobrachium rosenbergii). FAO Fisheries Technical Paper, 428 [Also published in Mandarin, with Arabic, French, Malayalam and Spanish versions in preparation].

New, M.B., and S. Singholka. 1985. Freshwater prawn farming: A manual for the culture of Macrobrachium rosenbergii. FAO Fisheries Technical Paper, 225, Rev. 1 [Also published in Farsi, French, Hindi, Spanish & Vietnamese].

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Shrimp from the ocean was not sufficient to meet consumer demand. Therefore shrimp aquaculture came into existence as a method of producing more shrimp and supplying the market with India shrimpShrimp from the ocean was not sufficient to meet consumer demand. Therefore shrimp aquaculture came into existence as a method of producing more shrimp and supplying the market with India shrimp products.

The India shrimp aquaculture industry has developed to a great extent today because of the huge demand for shrimp especially in the US and Japan.

Marshy coastal areas are ideal for India shrimp culture. Farmers dig a pond close to the coast so that they can fill it with ocean water and freshwater for the shrimp to swim in. The

ponds are filled wAbstractVarious substances in shrimp farm ponds can contaminate waters, including nutrients (nitrogen andphosphorus), metabolic wastes, antibiotics, or other medicines to protect shrimp, and suspended soilparticles from erosion. This report discusses ways to monitor these aspects of water quality, which isimportant from two standpoints for shrimp farmers. Incoming water used top supply shrimp ponds mustbe healthful and free of toxins to protect the growing shrimp, and effluent must be clean enough to avoid

harming aquatic ecosystems downstream, and in many places to meet water quality standards.The requirements and costs of setting up and operating a water quality analysis lab are provided, and thereport describes methods of sampling and analyzing water samples. Key aspects of lab operations,including testing the accuracy and precision of analytical procedures, and using quality control, rangecontrol, and means control charts are discussed, with numerical examples. The report recommendsprocedures for recording data and keeping accurate, organized records.The second part of the report covers a water quality monitoring project in the Gulf of Fonseca, whereshrimp aquaculture in Honduras is centered. The research—collaborative work among universities, privatesector aquaculturists (through the industry organization ANDAH), and government offices—hascontinued since 1993. Regular sampling of estuary water (near where pumps discharge incoming waterinto farm supply canal) is conducted by shrimp farmers and analyzed in the laboratory set up to anchor theprogram.Research results are shared with shrimp farms in order to maintain participation and encourage farmers tobecome more aware of the interaction between shrimp farming and the environment. Although shrimpfarm area has grown substantially since 1993, and production has grown some, no increase ineutrophication of estuaries in southern Honduras has been found over this period. (Riverine estuary waterquality changes notably by season, with nutrient concentrations higher in the dry season. Similar thoughmuch less pronounced changed occur in embayments.) Seeking to reduce the amount of nutrients enteringestuaries, aquaculture farms have reduced their feed and fertilizer input into shrimp ponds, and tried usinglower protein feeds. Salinity can also drop sharply in estuaries during the rainy season, from freshwaterrunoff.The report concludes that a strong industry association and support from government are critical toimplementing a successful water quality monitoring program and, ultimately, to maintaining aquaculturesustainable. ANDAH promotes effective regulation to protect the country’s natural resources. Themonitoring program is also supported by effective research and communication of results.valso put in pesticides and antibiotics into the pond in order to prevent the shrimps from falling prey to any disease. Also clean water has to be pumped in everyday. Otherwise with all the dirt, the India shrimps may not survive. On certain days 30% of new water may be

neeIntroductionShrimp farming is a common activity in coastal zones of many tropical and subtropical nations. Shrimpfarms are constructed near sources of brackish water or seawater, and ponds for shrimp culture are filledand maintained by pumping water from these sources. Fertilizers and feeds are both applied to ponds topromote shrimp growth. Nitrogen and phosphorus in fertilizers enhance phytoplankton production,enlarging the base of the food chain for shrimp. Feed is consumed directly by shrimp, often creating muchgreater production than with fertilizers alone. However, uneaten feed, feces, and other metabolic wastesincrease nutrient concentrations in pond water, also stimulating phytoplankton growth. Effluents fromshrimp ponds typically are enriched with nutrients, especially nitrogen and phosphorus, and they havehigh concentrations of particulate organic matter resulting from live plankton and decaying plankton.Waters in shrimp ponds usually are eutrophic, and the degree of eutrophication increases as shrimpproduction levels increase. In semi-intensive shrimp farming, water is flushed through ponds to reduceconcentrations of nutrients, phytoplankton, ammonia, and other potentially toxic metabolites, as well asorganic matter. In intensive shrimp farming, mechanical aeration is used to prevent low dissolved oxygenconcentrations, but water exchange (flushing) is also commonly used. Water flushed from ponds enterscoastal ecosystems, where it can cause eutrophication.Various chemicals may be applied to shrimp ponds in efforts to improve water quality or combat shrimpdiseases. These chemicals include liming materials, zeolite, chlorine, formalin, insecticides, andantibiotics or other drugs. Normally, natural processes within culture ponds deactivate these chemicals,but there is opportunity for their release into coastal waters (Boyd and Massaut 1999).

The land surface is disturbed when shrimp farms are constructed. Surface soils exposed by pondembankments, canals, roads, and other earthen infrastructure are often saline and do not revegetatenaturally. Erosion occurs and runoff from exposed, bare soil has high concentrations of suspended solids(soil particles). Soil particles are also suspended by water flowing through canals and water currentsgenerated by wind action and mechanical aeration. Another major source of suspended solids is thedraining of ponds during shrimp harvests. The outflowing water suspends sediment from pond bottoms,and effluents during the final phase of harvest are especially high in suspended solids (Boyd and Tucker1992).Shrimp farms thus represent potential sources of nutrient pollution, organic enrichment, turbidity andsedimentation in coastal waters. Some possibility exists for release of potentially toxic or bioaccumulativesubstances in pond effluents, as well. Shrimp farm effluents contain high concentrations of dissolved saltsfrom brackish water and seawater used to fill ponds, exchange water, and maintain water levels, sodischarge of effluents into freshwater areas can cause salinization. Obviously, indiscriminate discharge ofshrimp pond effluents can cause eutrophication, excessive turbidity, sedimentation, toxicity, andsalinization of aquatic habitats. These negative impacts can reduce the value of coastal ecosystems forother uses and adversely affect the native flora and fauna. Therefore, it is important to reduce the volumeand enhance the quality of shrimp pond effluents and minimize the possibility for adverse environmentalimpacts. It should be possible to greatly reduce these impacts through better practices, such as moreefficient use of feeds and fertilizers, reduction in water exchange, erosion control, restricted chemical use,installing sedimentation basins, and additional measures discussed in other case studies. Nevertheless, it isimpossible, at least in the near future, to eliminate completely discharge from shrimp ponds. Therefore,monitoring programs to assess shrimp farm effluents are needed. These monitoring programs candetermine whether better management practices (BMPs) installed or implemented on shrimp farmsactually improve effluent quality and reduce pollutant loads. Monitoring can also indicate whether coastalwater quality is deteriorating as a result of shrimp farming and other activities in an area. Monitoring2water quality should be an integral part of environmental management programs to reduce or preventnegative impacts of shrimp farming.This case study discusses the technical aspects of water quality monitoring programs for shrimp farming,and provides a review of a water quality monitoring program that has been ongoing for several years inthe shrimp farming area of Honduras (Figure 1).Figure 1. Map of Gulf of Fonseca and shrimp farming in southern Honduras.

Water Quality MonotoringThe purpose of monitoring is to determine water quality measures at a point in time in a specific area andto determine whether changes in water quality occur after that point. It would be desirable to start a waterquality monitoring program before the human activity of concern is initiated, in order to determinebaseline values absent that activity. With shrimp farming, this will often be impossible because shrimpfarms already have been operating in many areas for years. In this case, it is necessary to use the currentcondition as a beginning point, and from this reference, determine whether water quality deteriorates inthe future. Or it may be possible to find a nearby area without shrimp farming to use for comparison.Shrimp farming is seldom the only activity influencing water quality in an area, so changes in waterquality observed during a monitoring program may not result from shrimp farming alone. A water qualitymonitoring program for shrimp farming should take into account other possible sources of pollution andevaluate the amounts originating from all sources.3Most people consider monitoring programs useful strictly for evaluating the influence of some humanactivity on environmental quality. In the case of shrimp farming, however, maintaining good water qualityis also essential for shrimp production. If source water for shrimp farms is appreciably degraded by

pollution, impaired water quality in culture ponds will make producing shrimp much more difficult. Suchenvironmental stress results in less efficient growth of the shrimp, greater susceptibility to disease, andhigher mortality rates. Thus, it is important for shrimp farms to have information on the status of sourcewater quality and to know whether its quality is deteriorating.In spite of the many problems associated with evaluating the actual influence of shrimp farming on coastalwater quality, monitoring of farm effluent can be a powerful tool. In addition to providing information onthe state of coastal water quality, effluent monitoring can demonstrate the effects of changes in productionpractices and management inputs on pollutant loads in effluents. Adoption of best management practices(BMPs) may be the major method for reducing the negative environmental impacts of shrimp farming.Monitoring of farm effluents will allow an objective evaluation of the benefits of BMPs.In the future, greater emphasis will be given to monitoring water quality in shrimp farm effluents and incoastal waters near shrimp farms. These monitoring programs will most probably be designed andconducted by individuals or organizations with relatively little experience in water quality monitoring.Many of these programs are likely to be technically flawed and justifiably subject to criticism. It isimportant, therefore, to provide a discussion of the critical factors in the design and operation of waterquality monitoring programs for assessing shrimp farm effluents and their effects on coastal water quality.

VariablesA great number of water quality variables could be measured, but for practicality, only the importantvariables should be measured. The variables of most importance in shrimp farming effluents are thosemost likely to cause deterioration of conditions in coastal ecosystems (Table 1).4Table 1. Guidelines for water quality monitoring programs for shrimp farm effluents and coastal waters. Modified fromAustralian and New Zealand Environmental and Conservation Council 1992.Variable Reason for measuringGuidelines for protecting aquaticecosystemsWater temperature Has marked influence on chemicaland biological processesLess than 2oC changeDissolved oxygen Essential for aerobic aquatic life Not less than 5 to 6 mg/lPH Influences chemical and biologicalprocesses6.0 to 9.0Total ammonia nitrogen Plant nutrient and potential toxin;indicator of pollutionShould not exceed 3 mg/l in effluents.Nitrate nitrogen Potential toxin Should not exceed 0.005mg/l in coastalwaters.Total phosphorus Source of soluble inorganicphosphorus for plantsConcentrations of 0.001 to 0.1 mg/l incoastal waters can cause planktonblooms.Total nitrogen Source of dissolved inorganicnitrogen for plantsConcentrations of 0.1 to 0.75 mg/l incoastal waters can cause planktonblooms. Should not exceed 10 mg/l ineffluents.Chlorophyll a Indicator of phytoplanktonabundance and degree of

eutrophicationConcentrations above 1 to 10 μg/Lindicate eutrophication in coastalwaters.Total suspended solids Indicator of suspended soil particlesor suspended organic matter.Should not change by more than 10% ofseasonal mean in coastal waters.Biochemical oxygen demand Indicator of organic pollution Should not depress dissolved oxygenconcentrations below 5 or 6 mg/l.Salinity Can cause salinization Should not increase above 0.5 ppt infresh water. No limit recommended formarine or brackish waters.Secchi disk visibility Index of water clarity or turbidity Should not change by more than 10% ofseasonal mean in coastal waters.Note: The guidelines for protecting aquatic ecosystems are not effluent limits; they apply to the receiving water bodyoutside the mixing zone. These limits do not apply within the mixing zone. Effluent concentration limits must beestablished so that the above limits are maintained within the receiving water outside of the mixing zone.A number of other variables (e.g., nitrate-nitrogen, soluble reactive phosphorus, chemical oxygen demand,particulate organic matter, volatile solids, oil and grease, settleable solids, and turbidity), could beincluded, but we do not think that these analyses are necessary. It is preferable to select a few importantindicators that can be reliably measured and interpreted rather than to analyze a wide range of variables,some of which cannot be measured reliably or easily interpreted. Measurements of nitrate-nitrogen andsoluble reactive phosphorus do not appreciably supplement total nitrogen and total phosphorus data forevaluating nutrient pollution. Chemical oxygen demand is difficult to measure in brackish water orseawater because of chloride interference. Biochemical oxygen demand provides adequate information onthe potential of effluents for organic enrichment. It is also much easier to interpret biochemical oxygendemand data than data on chemical oxygen demand, particulate organic matter, volatile solids, and othermeasures of organic enrichment. Oil and grease generally result from fuel or lubricant leaks into theculture system. Oil and grease can be prevented from entering systems through use of BMPs, so thatgathering data on oil and grease, which are difficult to interpret, would not be required. Data on settleablesolids and turbidity only supplement total suspended solids information. Of course, turbidity is easy tomeasure, and some may want to substitute turbidity for total suspended solids for analytical convenience.5As pointed out earlier, many chemical substances are applied to shrimp ponds, but if properly used thesesubstances will be degraded in ponds. Chemicals that are unsafe for use in shrimp ponds should bebanned, and only acceptable chemicals applied. Even acceptable chemicals can cause adverse effectswhen not applied properly or when water is not retained in ponds until residues have degraded. It is verydifficult to monitor pond effluents for residues of chlorine, formalin, and antibiotics or other drugs usedfor disease control, however. It would be much more efficient to develop BMPs for use of chemical agentsin ponds and monitor the adoption and use of the BMPs.

Analytical TechniquesThere are several methods of determining concentrations of most water quality variables. In a monitoringprogram, suitable methodology should be selected and maintained during the program. Different methodsfor determining a water quality variable may not provide the same results, and changing methodologyduring the program can cause difficulties in interpreting findings. It is highly desirable to use standardanalytical protocols for a monitoring program, and it would be tremendously beneficial if all monitoringprogram for shrimp farming used the same protocols. Methods for measuring water quality variables arerecommended in Table 2.Table 2. Recommended methods and equipment for water quality analyses for monitoring programs for shrimpfarming.

Variable MethodWater temperature Mercury thermometer.Dissolved oxygen Standard dissolved oxygen meter (Yellow Springs Instrument Company,Yellow Springs, Ohio, USA, or equivalent).pH Standard, line-powered, laboratory pH meter with glass electrode.Total ammonia nitrogen Phenate method (Clesceri et al. 1998 or Grasshoff et al. 1976). Thesalicylate method (Verdouw et al. 1978) could be used as an alternative.Nitrate nitrogen Diazonium salt method (Clesceri et al. 1998 or Grasshoff et al. 1976).Total phosphorus Persulfate digestion with ascorbic acid finish (Gross and Boyd 1998).Total nitrogen Persulfate digestion with ultraviolet spectrophotometric finish (Gross et al.1999).Chlorophyll a Acetone extraction with spectrophotometric finish (Clesceri et al. 1998 orBoyd and Tucker 1992).Total suspended solids Glass fiber filtration and gravimetry (Clesceri et al. 1998).Biochemical oxygen demand Standard 5-day test (Clesceri et al. 1998).Salinity Line-powered conductivity/salinity meter. Chloride concentration in mg/l x1.80655 (Clesceri et al. 1998) or hand-held salinometer are alternatives.Some investigators may want to use water analysis kits for monitoring water quality. These kits aresuitable for obtaining water quality data for pond management decisions, but they should not be used forwater quality monitoring.6SamplingLocationsThe selection of sampling stations for water quality monitoring programs will vary with location andpurpose of the monitoring effort. Where the interest is to evaluate the water supply for a farm or todetermine the benefits of changes in management techniques, such as adoption of BMPs, the samplingstations should be at the water intake (pump station) and at the effluent outfall. On some shrimp farms,there may be a reservoir for intake water, a long canal for discharge, or the effluent may pass through asedimentation area. In such cases, additional sampling stations should be selected at the outflow structureof the reservoir (where its water enters culture ponds) and the entrances to the canal and the sedimentationarea.In many instances, drainage canals are excavated to conduct pond effluent to receiving waters (estuaries)by gravity. In such cases, water in the drainage canal is subject to tidal action and probably is not a goodindicator of farm effluent unless a pond is actively drained during low tide. Of course, if drainage canalsare close to receiving waters, and effluents are pumped to a sedimentation lagoon or estuary, then samplescould be collected from the pump discharge. Otherwise, we suggest that samples be collected randomlyfrom 1) ponds undergoing routine water exchange, and 2) ponds being harvested.For monitoring water quality in coastal waters receiving effluents from shrimp farms, several to manysampling stations should be selected. These stations should be located near certain shrimp farm outfalls,near the inflows of selected streams, near pumping stations on particular shrimp farms, in the larger bodyof the estuary or along the seashore, as well as some places well removed from the immediate influence offarm outfalls. It is important to select sampling stations to provide a gradient, extending from areasreceiving direct farm discharge to areas that receive less discharge, to those that do not receive directdischarge from shrimp farms. If there are municipal or industrial effluent outfalls in the sampling area,these locations should also be included in the sampling program. By using a detailed map of the area, it isusually possible to develop a good monitoring program by establishing 15 to 30 sampling stations.Once the sampling stations have been selected, they should be permanently marked in the field and on amap so that samples can always be taken from the same places. Consideration should be given toaccessibility, so that obtaining all samples on each sampling date can be done. For example, a stationlocated 1 km offshore may not be accessible by small boat during seasons with heavy seas, and roads tosome sites may not be open during the rainy season.

Sampling FrequencyIn evaluating BMPs, sampling should be done at weekly intervals or more frequently. When BMPsinvolve changes in harvest techniques, it may be desirable to sample effluents at intervals of a few hoursduring pond draining.Sampling to ascertain changes in the water supply quality or to determine changes in coastal water qualityover time can be taken less frequently. For general purposes, we recommend that samples be taken atbiweekly intervals.Time of SamplingAll samples should be taken on the same day if possible, but it usually takes several hours to collect them.We recommend beginning sampling early in the morning and completing the procedure as quickly aspossible. Where monitoring programs have many sampling stations or several remote stations, it may notbe possible to take all samples in one day.7Samples can be taken on 2 or more days, but all sampling for a particular month should be done within thesame week and preferably within 2 or 3 days.Other Aspects of SamplingThe samples from pump stations and canals can be dipped directly from the stream of flow. A 1-m columnsampler (Boyd and Tucker 1992) is recommended for taking samples from coastal waters.Temperature and dissolved oxygen measurements should be made in situ, but water for the other analysesshould be placed in plastic 1 litre (l) or 2 l bottles. At least 2 l of sample should be collected at eachsampling station. Sample bottles should be placed in ice chests and kept cool. Holding time should notexceed 6 hours if possible.

Field and Laboratory RequirementsThe field equipment needed for a water quality program consists of a vehicle, a boat or boats for travel tothe sampling locations, water sampler, sample bottles, ice chests, thermometer, Secchi disk, and dissolvedoxygen meter. If salinity is measured in the field, a salinometer will also be required.The laboratory should be properly sealed to minimize dust and insect intrusions, and air conditioned. Airconditioning cooling capacity should be sufficient to maintain the laboratory air temperature at 20oC.Split-unit air conditioners are preferred because the cooling unit is not in direct contact with the outsideenvironment. If window air conditioners are used, a dust seal must be installed around the unit, and thefilter must be cleaned regularly. The lab should be equipped with a manual transfer, back-up generatorwhere electrical power is unreliable. It may be necessary to connect analytical and computing equipmentto voltage stabilizers or uninterrupted power supplies. A reliable source of water is needed to washglassware and prepare distilled or deionized water. Installation of a water cistern may be necessary toensure an uninterrupted water supply. Effluents from the laboratory should be discharged to a septic tankor in another manner that minimizes environmental impacts. Toxic wastes should be neutralized ordeactivated and disposed of in a responsible manner.Laboratory instruments include a spectrophotometer with ultraviolet capability, pH meter,conductivity/salinity meter, autoclave, forced-draft drying oven, biochemical oxygen demand (BOD)incubator, top-loading balance, semi-micro analytical balance, dissolved oxygen meter with BOD bottleprobe, apparatus for glass fiber filtration, and magnetic stirrers. It is important to duplicate keyinstruments such as pH meters and oxygen meters so that instrument failure does not result in lost data. Asource of deionized or distilled water is necessary. The laboratory should have a fume hood, but this is notabsolutely essential. In addition to the instruments, all reagents and glassware needed for the analysesmust be available. Only analytical-grade reagents should be used in analyses. Care must be exercised tomaintain a reserve supply of glassware and reagents to avoid delays and loss of data. The lab also requiressufficient bench space for conducting the analyses, a refrigerator for storing reagents, a large sink for

washing glassware, and space for draining and drying glassware. All glassware should be acid-washedmonthly.At least one computer system (CPU, keyboard, monitor, and printer) should be available for data storage,analysis, and reporting, as well as for general laboratory correspondence. The computer should haveenough RAM and hard drive storage capacity to allow efficient management and analysis of data. Back-upcopies of all data files should be made weekly, documented, and stored in a secure location.Most sampling programs will need two field workers to collect the samples, and a well-trained analystwith two assistants to conduct the analyses. Of course, the analyst and an assistant could also be8responsible for collecting samples. A worker to wash glassware and maintain an orderly laboratory isessential. A secretary must also be available to assist with record keeping and clerical tasks.

Reliability of DataA system of quality control should be included in a water quality monitoring program. The results ofanalyses will be compared among locations and over time, so it is critical that differences in water qualityamong sampling stations or differences over time reflect true differences rather than analytical variation orerror. Unfortunately, most monitoring efforts that we observed did not have a quality control component.This does not imply that the data were not adequate, but there is no way to verify the reliability of the data.Of course, most papers resulting from research efforts do not use quality control, and the reader must trustthe investigator. Nevertheless, for monitoring studies, it is much better to have a quality controlcomponent so that there is proof of readability. Therefore, a discussion of quality control will be provided.

Accuracy and PrecisionPrecision refers to agreement of two or more replicate determinations of a given value. Accuracy refers tothe closeness between a measured value and the true value. To illustrate precision and accuracy, considerdeterminations of salinity made by four students. The instructor determined that the sample had a salinityof 25.2 ppt (considered to be the true value). The results follow:ReplicateStudent a b c d MeanStandarddeviation1 25.1 25.2 24.9 25.2 25.1 0.142 23.1 23.2 23.0 23.1 23.1 0.083 22.1 20.1 23.2 19.1 21.1 1.864 22.2 23.2 28.7 25.1 24.8 2.86Student 1 obtained both high precision (low standard deviation) and accuracy. While Student 2 achievedgood precision, accuracy was poor. Student 3 obtained low accuracy and low precision. By fortunatecircumstances, Student 4 obtained good accuracy in spite of low precision. Obviously, the most desirableresults were those of Student 1.Relative accuracy may be expressed as:Percent relative error = | True value – measured value | x 100.True value

Quality ControlStandard Operating ProceduresAn important component of a laboratory quality control program is written Standard Operating Procedures(SOPs). The SOPs describe in detail all methodologies used in each part of the program, from samplingsite selection, sample collection and handling, and analytical methods, to data handling, analysis, andreporting. All participants in an estuarine monitoring program are expected to know and comply with all

SOPs.Precision and Accuracy ChecksOnce an analyst has accepted a certain method of analysis, obtained the necessary reagents and equipment,and learned to perform the analysis, precision of the measurements should be estimated. Precision can bedetermined on standard solutions of the substance to be measured, but a better procedure is to obtain real9water samples and make the precision estimates on them. An acceptable procedure is to obtain three watersamples: one low, one intermediate, and one high in concentration of the substance to be measured. Theanalyst then makes a number of repetitive measurements on each sample and calculates the mean andstandard deviation or confidence interval for individual measurements. The US Environmental ProtectionAgency (1972) recommended using 7 repetitive measurements, but any number of samples between 5 and10 is suitable.The procedure is illustrated in Table 3 for the determination of total suspended solids (TSS).Table 3. Illustration of precision of total suspended solids analysisTotal Suspended SolidsReplicate Sample A Sample B Sample C1 18.0 65.6 155.62 16.8 64.4 152.03 17.8 64.5 159.14 18.0 63.1 155.85 17.5 64.1 157.26 18.8 66.9 150.37 19.0 63.0 160.5Mean 18.0 64.5 155.8Standard deviation 0.75 1.38 3.6495% confidence interval 1.83 3.36 8.92Coefficient of variation (%) 4.17 2.13 2.34However, the results indicate that waters with a high concentration of total suspended solids can beanalyzed with slightly better precision than waters with a lower concentration of TSS. However, theresults also allow us to make the summary statement that, in the range from 18.0 to 155.8 mg/liter totalsuspended solids, a measured value should fall within 8.92 mg/liter of the mean 95% of the time.The accuracy of procedures can be checked by adding a known amount of the substance to be measured todistilled water, analyzing the resulting standard solution, and determining how closely the measured valueapproaches the true value (represented by the concentration of the standard solution). It is, again, better todetermine the accuracy of a method with measurements involving natural water. This can be achieved bydetermining the concentration of the substance in natural water and then adding a known amount of thesubstance to the natural water and determining the percentage recovery. This technique, called spikerecovery, is illustrated for the determination of total ammonia nitrogen. The water sample had a measuredtotal ammonia nitrogen concentration of 1.51 mg/liter. An ammonia nitrogen spike of 1.0 mg/l was addedto the sample to provide a concentration of 2.51 mg/l of total ammonia nitrogen. Replicate determinationswere made producing the following data:Replicate Total ammonia nitrogen (mg/liter)1 2.502 2.393 2.354 2.455 2.536 2.407 2.51Mean 2.45Recovery = 2.45 x 100 = 97.6%

1.51 + 1.00

10We may state that for water containing 2.51 mg/l total ammonia nitrogen, the recovery was 97.6% . Thepercent recovery is a good approximation of accuracy, but the true concentration of substance can neverbe known with absolute certainly.Obviously, an analyst cannot afford to make a large number of repetitive measurements, conduct a spikerecovery for each sample, or analyze a standard solution with each sample. The analyst can and shouldmake periodic checks of precision and accuracy, though. For example, about 5–10% of the samples shouldbe analyzed in duplicate. If the duplicate measurements do not agree with the known precision of themethod, the results are not reliable and any problem in the technique must be located and corrected.Remember, depending upon the confidence level selected, 1% or 5% of the measurements may falloutside the confidence interval by chance alone, and occasional deviant values (called outliers) are nocause for alarm. Similarly, periodic checks of accuracy should be made with spike recovery tests or byanalyses of standard solutions.For colorimetric methods, calibration graphs must be prepared by measuring the absorbance of knownconcentrations of the substance being measured and plotting the results. These graphs should be verifiedfrequently by analyzing known concentrations of the substance in question.It is important to understand that the common practice of making duplicate or triplicate analyses of allsamples is essentially worthless. Analysts should not waste time and reagents on checking every sample,and duplicate analyses provide no useful estimate of accuracy.Quality Control ChartsA more refined quality control procedure involves use of quality control charts, a highly recommendedmethod for monitoring programs. Charts for maintaining quality control were originally developed formanufacturing, but they can be adapted for use by laboratories that conduct water analyses. The theorybehind these charts is explained by the US Environmental Protection Agency (1972). We will present onlythe information necessary for construction and use of quality control charts.A quality control chart consists of a graph on which the vertical scale represents the results and thehorizontal scale indicates the sequence of the results (time). Warning and control limits and the means ofthe statistical measures under consideration are indicated on the graph. The results are plotted over time,and from these plots it can be ascertained whether precision and accuracy are acceptable. The mostcommonly used quality control charts are range charts, which reveal the control of precision, and meanscharts, which reveal the control of accuracy. The greatest value of quality control charts is that trends ofchange in precision and accuracy over time may be detected.Control ChartsA range control chart for replicate measurements is made by calculating a mean range (R), a warning limit(WL), and a control limit (CL). A minimum of 20 range values (difference between the lowest and highestvalues in replicate analyses of a sample) are used to make the chart. The factors for computing control onrange control charts are as follows:Number of replicates (n) Factors for control limits (D4)2 3.273 2.584 2.285 2.126 2.0011The necessary equations are:

R =

ded, which is quite a lot of water.

In a country like India, majority of the rural population is dependent on agriculture. Hence most people get their water from rivers or streams or wells. When a shrimp farm flushes out polluted water, it goes back into the ground, river or stream. So not only are the village people affected, this water is also sometimes used to supply nearby towns. Hence the aquaculture of India shrimp could lead to a lot of diseases if this pollution is not controlled. Shrimps also need salt water to grow. The brakish water can destroy the crops and also make the farms barren.

The India shrimp aquaculture would help the village people by providing them with more employment. Although some people did get employed, but these farms were more capital intensive and did not need a lot of labor. What is most important is that the India shrimp companies were not forced to clean up their pollution.

Hence the India shrimp aquaculture has both its positive and negative aspects. On one hand, shrimp production has increased to meet growing demand in the global market. India has earned more foreign exchange. On the other hand, people are sometimes badly affected by pollution from the shrimp farms

products.

The India shrimp aquaculture industry has developed to a great extent today because of the huge demand for shrimp especially in the US and Japan.

MarsShrimp from the ocean was not sufficient to meet consumer demand. Therefore shrimp aquaculture came into existence as a method of producing more shrimp and supplying the market wShrimp from the ocean was not sufficient to meet consumer demand. Therefore shrimp aquaculture came into existence as a method of producing more shrimp and supplying the market with India shrimp products.

The India shrimp aquaculture industry has developed to a great extent today because of the huge demand for shrimp especially in the US and Japan.

Marshy coastal areas are ideal for India shrimp culture. Farmers dig a pond close to the coast so that they can fill it with ocean water and freshwater for the shrimp to swim in. The ponds are filled with shrimp larvae. The farmers also put in pesticides and antibiotics into the pond in order to prevent the shrimps from falling prey to any disease. Also clean water has to be pumped in everyday. Otherwise with all the dirt, the India shrimps may not survive. On certain days 30% of new water may be needed, which is quite a lot of water.

In a country like India, majority of the rural population is dependent on agriculture. Hence most people get their water from rivers or streams or wells. When a shrimp farm flushes out polluted water, it goes back into the ground, river or stream. So not only are the village people affected, this water is also sometimes used to supply nearby towns. Hence the aquaculture of India shrimp could lead to a lot of diseases if this pollution is not controlled. Shrimps also need salt water to grow. The brakish water can destroy the crops and also make the farms barren.

The India shrimp aquaculture would help the village people by providing them with more

employment. Although some people did get employed, but these farms were more capital intensive and did not need a lot of labor. What is most important is that the India shrimp companies were not forced to clean up their pollution.

Hence the India shrimp aquaculture has both its positive and negative aspects. On one hand, shrimp production has increased to meet growing demand in the global market. India has earned more foreign exchange. On the other hand, people are sometimes badly affected by pollution from the shrimp farms

ith India shrimp products.

The India shrimp aquaculture industry has developed to a great extent today because of the huge demand for shrimp especially in the US and Japan.

Marshy coastal areas are ideal for India shrimp culture. Farmers dig a pond close to the coast so that they can fill it with ocean water and freshwater for the shrimp to swim in. The ponds are filled with shrimp larvae. The farmers also put in pesticides and antibiotics into the pond in order to prevent the shrimps from falling prey to any disease. Also clean water has to be pumped in everyday. Otherwise with all the dirt, the India shrimps may not survive. On certain days 30% of new water may be needed, which is quite a lot of water.

In a country like India, majority of the rural population is dependent on agriculture. Hence most people get their water from rivers or streams or wells. When a shrimp farm flushes out polluted water, it goes back into the ground, river or stream. So not only are the village people affected, this water is also sometimes used to supply nearby towns. Hence the aquaculture of India shrimp could lead to a lot of diseases if this pollution is not controlled. Shrimps also need salt water to grow. The brakish water can destroy the crops and also make the farms barren.

The India shrimp aquaculture would help the village people by providing them with more employment. Although some people did get employed, but these farms were more capital intensive and did not need a lot of labor. What is most important is that the India shrimp companies were not forced to clean up their pollution.

Hence the India shrimp aquaculture has both its positive and negative aspects. On one hand, shrimp production has increased to meet growing demand in the global market. India has earned more foreign exchange. On the other hand, people are sometimes badly affected by pollution from the shrimp farms

hy coastal areas are ideal for India shrimp culture. Farmers dig a pond close to the coast so that they can fill it with ocean water and freshwater for the shrimp to swim in. The ponds are filled with shrimp larvae. The farmers also put in pesticides and antibiotics into the pond in order to prevent the shrimps from falling prey to any disease. Also clean water has to be pumped in everyday. Otherwise with all the dirt, the India shrimps may not survive. On certain days 30% of new water may be needed, which is quite a lot of water.

In a country like India, majority of the rural population is dependent on agriculture. Hence most people get their water from rivers or streams or wells. When a shrimp farm flushes out polluted water, it goes back into the ground, river or stream. So not only are the village people affected, this water is also sometimes used to supply nearby towns. Hence the aquaculture of India shrimp could lead to a lot of diseases if this pollution is not controlled. Shrimps also need salt water to grow. The brakish water can destroy the crops and also

make the farms barren.

The India shrimp aquaculture would help the village people by providing them with more employment. Although some people did get employed, but these farms were more capital intensive and did not need a lot of labor. What is most important is that the India shrimp companies were not forced to clean up their pollution.

Hence the India shrimp aquaculture has both its positive and negative aspects. On one hand, shrimp production has increased to meet growing demand in the global market. India has earned more foreign exchange. On the other hand, people are sometimes badly affected by pollution from the shrimp farms