Marine shrimp farming

Marine shrimp farming is an aquaculture business for the cultivation of marine shrimp or prawns Bolded numbers indicate some recognizable disease events.

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thumb|From top to bottom: pieces of the carapace of Litopenaeus vannamei; a harvested healthy L. vannamei of size 66 (17 [[gram|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. In Ecuador alone, production suffered heavily in 1989 (IHHN), 1993 (Taura), and 1999 (whitespot). Another reason for sometimes wild changes in shrimp farm output are the import regulations of the destination countries, which do not allow shrimp contaminated by chemicals or antibiotics to be imported.

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

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

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. The published literature on that topic shows large discrepancies, and much of the available data are of anecdotal nature. Estimates of the labor intensity of shrimp farms range from about one-third to three times more than when the same area was used for rice paddies, with much regional variation and depending on the type of farms surveyed. In general, intensive shrimp farming requires more 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. 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; a study from India arrived at a salary increase of about 1.6,

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 their income by a factor of ten by switching from growing rice to farming shrimp. An Indian study from 2003 arrives at similar figures for shrimp farming in the East Godavari district in Andhra Pradesh.

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

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 ==

right|thumb|Mangrove estuaries provide a habitat for many animals and plants.

thumb|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.]]

thumb|right|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. Liming can be applied to counteract to some extent the acidification of the water in ponds on acid sulfate soil, such as mangrove soils.]]

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 had vanished. Shrimp farming was a major cause of this, accounting for over a third of it according to one study; other studies report between 5% and 10% globally, with enormous regional variability. Other causes of mangrove destruction are population pressure, logging, pollution from other industries, or conversion to other uses such as salt pans. Mangroves, through their roots, help stabilize a coastline and capture sediments; their removal has led to a marked increase of erosion and less protection against floods. Mangrove estuaries are also especially rich and productive ecosystems and provide the spawning grounds for many species of fish, including many commercially important ones.

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 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.

Prolonged use of a pond can lead to an incremental buildup of a sludge at the pond's bottom from waste products and excrement. 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. A joint programme of the World Bank, the Network of Aquaculture Centres in Asia-Pacific (NACA), the WWF, and the FAO was established in August 1999 to study and propose improved practices for shrimp farming. Some existing attempts at sustainable export-oriented shrimp farming marketing the shrimp as "ecologically produced" are criticized by NGOs as being dishonest and trivial window-dressing.

Yet, the industry has been slowly changing since about 1999. It has adopted the "best management practices" developed by the World Bank program, for example, and others. and instituted educational programs to promote them. Due to the mangrove protection laws enacted in many countries, new farms are usually of the semi-intensive kind, which are best constructed outside mangrove areas anyway. There is a trend to create even more tightly controlled environments in these farms, with the hope to achieve better disease prevention. Waste water treatment has attracted considerable attention; modern shrimp farms routinely have effluent treatment ponds where sediments are allowed to settle at the bottom and other residuals are filtered. As such improvements are costly, the World Bank 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. The long-term effects of these recommendations and industry trends cannot be evaluated conclusively yet.

Still, it was reported in 2012 that one pound of frozen shrimp adds one ton of carbon dioxide to the atmosphere, more than ten times that generated to produce the same weight of beef raised on cleared rainforest land.

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

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

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 elites who have easier access to credits, subsidies, and permits and thus are more likely to become shrimp farmers and benefit more. In Bangladesh, on the other hand, local elites were opposing shrimp farming, which was controlled largely by an urban elite. 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.

Sustainable practices

Although shrimp farming has disrupted social structures, it is possible for both commercial industries and independent farmers to succeed. Closed system shrimp aquaculture for instance, is becoming widely used in the US and is making its way to Southeast Asia. This system takes place indoors in moderate sized pools which efficiently circulates the water. In some cases filter feeders such as shellfish and other fish are introduced in the system, feeding off nutrients in the water that would otherwise be cycled out. This option is more environmentally safe than large scale intensive farming practices. Unfortunately, this system is capital intensive and would be difficult for small scale, independent shrimp farmers to acquire. However, this would be an excellent alternative for larger shrimp industries in Thailand.

Another alternative would be to revert to traditional shrimp farming practices, without overstocking and the use of harmful chemicals. This would be an ideal option for small scale shrimp farmers supplying for their own community as well as creating an independent food source.

Notes

References

Bibliography

FIGIS: Data extracted from the FAO Fisheries Global Aquaculture Production Database for the seven commonly farmed species plus Pennaeus spp. The most recent data sets are for 2007 and sometimes contain estimates. Last accessed November 19, 2009.
FAO: GLOBEFISH Shrimp Market Reports; FAO GlobeFish; 2003 – 2005.
FAO: The State of World Fisheries and Aquaculture, 2008.
FoodMarket: Shrimp Production; data from GlobeFish, 2001. URL last accessed June 23, 2005.
Global Aquaculture Alliance: Antidumping. URL last accessed August 23, 2005.
Gulf States Marine Fisheries Commission: Non-Native Species Summaries: Yellowhead Virus (YHV), 2003. URl last accessed June 23, 2005.
Gulf States Marine Fisheries Commission: Non-Native Species Summaries: White Spot Syndrome Baculovirus Complex (WSBV), 2003. URL last accessed June 23, 2005.

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B. Rosenberry: Shrimp Feeds, ShrimpNews, August 2004. URL last accessed June 28, 2005.

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External links

McQuaid, J.: Thailand transformed by shrimp boom, March 28, 1996. Part of a series for which the newspaper The Times-Picayune, New Orleans, won the Pulitzer Prize in the category "public service" in 1997.
Network of Aquaculture Centres in Asia-Pacific (NACA) has many of the World Bank et al. reports and a lot of current information about shrimp farming in Asia.
Scampi.nu is a Swedish web site critical of shrimp farming that has many excellent links to English articles.
Mai Po gei wai is a WWF–managed extensive shrimp farm in Hong Kong.
Monterey Bay Aquarium 'Seafood Guide' offers good information on choosing seafood that is caught using sustainable and environmentally aware methods.
Environmental Justice Foundation The Environmental Justice Foundation has created several video and written reports about the damaging shrimp farming causes to coastal habitats.
Shrimp farming, from Greenpeace.
Australian Prawn Farming Manual Download page of the 159 page PDF published by The State of Queensland, Department of Primary Industries and Fisheries