Aquaculture

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Aquaculture installations in southern Chile.

Aquaculture is the farming of freshwater and saltwater organisms including molluscs, crustaceans and aquatic plants. Unlike fishing, aquaculture, also known as aquafarming, implies the cultivation of aquatic populations under controlled conditions. [1] Mariculture refers to aquaculture practiced in marine environments. Particular kinds of aquaculture include algaculture (the production of kelp/seaweed and other algae), fish farming, shrimp farming, oyster farming, and the growing of cultured pearls. Particular methods include aquaponics, which integrates fish farming and plant farming.

Contents

[edit] History

Workers harvest catfish from the Delta Pride Catfish farms in Mississippi

Aquaculture has been used in China since circa 2500 BC. When the waters lowered after river floods, some fishes, mainly carp, were held in artificial lakes. Their brood were later fed using nymphs and silkworm feces, while the fish themselves were eaten as a source of protein. By a fortunate genetic mutation, this early domestication of carp led to the development of goldfish in the Tang Dynasty.

The Hawaiian people practiced aquaculture by constructing fish ponds (see Hawaiian aquaculture). A remarkable example from ancient Hawaii is the construction of a fish pond, dating from at least 1,000 years ago, at Alekoko. According to legend, it was constructed by the mythical Menehune. The Japanese practiced cultivation of seaweed by providing bamboo poles and, later, nets and oyster shells to serve as anchoring surfaces for spores. The Romans often bred fish in ponds.

The practice of aquaculture gained prevalence in Europe during the Middle Ages, since away from the seacoasts and the big rivers, fish were scarce and thus expensive. However, improvements in transportation during the 19th century made fish easily available and inexpensive, even in inland areas, causing a decline in the practice. When the first North American fish hatchery was constructed on Dildo Island, Newfoundland Canada in 1889, it was the largest and most advanced in the world.

Americans were rarely involved in aquaculture until the late 20th century, but California residents harvested wild kelp and made legal efforts to manage the supply starting circa 1900, later even producing it as a wartime resource.[2]

Tilapia, a commonly farmed fish due to its adaptability

Actually, there was keen interest in aquaculture in the United States as early as 1859 when Stephen Ainsworth of West Bloomfield, NY began his experiments with brook trout. By 1864 Seth Green had established a commercial fish hatching operation at Caledonia Springs, near Rochester, NY. By 1866, with the involvement of Dr. W. W. Fletcher of Concord Mass, artificial fish hatching operations were under way in both Canada and the United States.[3]

In contrast to agriculture, the rise of aquaculture is a contemporary phenomenon. According to professor Carlos M. Duarte about 430 (97%) of the aquatic species presently in culture have been domesticated since the start of the 20th century, and an estimated 106 aquatic species have been domesticated over the past decade. The domestication of an aquatic species typically involves about a decade of scientific research. Current success in the domestication of aquatic species results from the 20th century rise of knowledge on the basic biology of aquatic species and the lessons learned from past success and failure. The stagnation in the world's fisheries and overexploitation of 20 to 30% of marine fish species have provided additional impetus to domesticate marine species, just as overexploitation of land animals provided the impetus for the early domestication of land species

In the 1960s, the price of fish began to climb, as wild fish capture rates peaked and the human population continued to rise. Today, commercial aquaculture exists on an unprecedented, huge scale. In the 1980s, open-netcage salmon farming also expanded; this particular type of aquaculture technology remains a minor part of the production of farmed finfish worldwide, but possible negative impacts on wild stocks, which have come into question since the late 1990s, have caused it to become a major cause of controversy.[4]

[edit] World production

In 2004, the total world production of fisheries was 140.5 million tonnes of which aquaculture contributed 45.5 million tonnes or about 32% of the total world production.[5] The growth rate of worldwide aquaculture has been sustained and rapid, averaging about 8 percent per annum for over thirty years, while the contribution to the total from wild fisheries has been essentially flat for the last decade.

[edit] Production by country

Aquaculture is an especially important economic activity in China. Between 1980 and 1997, the Chinese Bureau of Fisheries reports, aquaculture harvests grew at an annual rate of 16.7 percent, jumping from 1.9 million to nearly 23 million tons. In 2005 China accounted for 70% of the world's aquaculture production[6][7].

In the US, approximately 90% of all shrimp consumed is farmed and imported.[8] In recent years salmon aquaculture has become a major export in southern Chile, especially in Puerto Montt and Quellón, Chile's fastest-growing city.

[edit] Environmental impacts

The concentrated nature of aquaculture often leads to higher than normal levels of fish waste in the water. Fish waste is organic and composed of nutrients necessary in all components of aquatic food webs. In some instances such as nearshore, high-intensity operations, increased waste can adversely affect the environment by decreasing dissolved oxygen levels in the water column. Onshore recirculating aquaculture systems, facilities using polyculture techniques, and properly-sited facilities (e.g. offshore or areas with strong currents) are examples of ways to reduce or eliminate the negative environmental effects of fish waste.

Aquaculture can be more environmentally damaging than exploiting wild fisheries.[9] Some heavily-farmed species of fish, such as salmon, are maintained in net-contained environments. Unused feed and waste products can contaminate the sea floor and cultured fish can escape from these pens. Escapees can out compete wild fish for food and spread disease, as well as dilute wild genetic stocks through interbreeding. Farming carnivorous fish like salmon may actually increase the pressure on wild fish, as for farming one kilo of farmed fish up to six kilo of wild fish are used for feeding.[10] However considerable research and commercial feed improvements during the 1990s & 2000s has lessened many of these environmental impacts [11]

Certain forms of aquaculture such as the culture of seaweeds and filter feeding bivalve mollusks such as oysters, clams, mussels and scallops are relatively benign environmentally. Seaweeds act to extract nutrients such as inorganic nitrogen and phosphorus directly from the water, [12] and filter feeding molluscan shellfish can extract organic nutrients as they feed on particulate phytoplankton and detritus. [13]

Despite the environmental concerns, aquaculture profitability could be high enough that money could go back into promoting sustainable practices. [14] Furthermore, new methods minimize the risk of biological and chemical pollution through minimizing stress to fish, vaccinating fish, fallowing netpens, and applying Integrated Pest Management. Vaccines are being used more and more to reduce antibiotic use for disease control in aquaculture. [15]

[edit] Types of aquaculture

[edit] Algaculture

Main article: Algaculture
An open pond Spirulina farm

Algaculture is a form of aquaculture involving the farming of species of algae. The majority of algae that are intentionally cultivated fall into the category of microalgae, also referred to as phytoplankton, microphytes, or planktonic algae.

Macroalgae, commonly known as seaweeds, also have many commercial and industrial uses, but due to their size and the specific requirements of the environment in which they need to grow, they do not lend themselves as readily to cultivation on a large scale as microalgae and are most often harvested wild from the ocean.

[edit] Fish farming

Main article: Fish farming

Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. It involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Fish species raised by fish farms include salmon, catfish, tilapia, cod, carp, trout and others.

Increasing demands on wild fisheries by commercial fishing operations have caused widespread overfishing. Fish farming offers an alternative solution to the increasing market demand for fish and fish protein.

[edit] Freshwater prawn farming

Main article: Freshwater prawn farm

A freshwater prawn farm is an aquaculture business designed to raise and produce freshwater prawn or shrimp for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farming. Unique problems are introduced by the developmental life cycle of the main species (the giant river prawn, Macrobrachium rosenbergii).[16]

The global annual production of freshwater prawns (excluding crayfish and crabs) in 2003 was about 280,000 tons, of which China produced some 180,000 tons, followed by India and Thailand with some 35,000 tons each. Additionally, China produced about 370,000 tons of Chinese river crab (Eriocheir sinensis).[17]

[edit] Integrated multi-trophic aquaculture

Main article: Integrated Multi-trophic Aquaculture

Integrated Multi-Trophic Aquaculture (IMTA) is a practice in which the by-products (wastes) from one species are recycled to become inputs (fertilizers, food) for another. Fed aquaculture (e.g. fish, shrimp) is combined with inorganic extractive (e.g. seaweed) and organic extractive (e.g. shellfish) aquaculture to create balanced systems for environmental sustainability (biomitigation), economic stability (product diversification and risk reduction) and social acceptability (better management practices).[12]

"Multi-Trophic" refers to the incorporation of species from different trophic or nutritional levels in the same system.[18] This is one potential distinction from the age-old practice of aquatic polyculture, which could simply be the co-culture of different fish species from the same trophic level. In this case, these organisms may all share the same biological and chemical processes, with few synergistic benefits, which could potentially lead to significant shifts in the ecosystem. Some traditional polyculture systems may, in fact, incorporate a greater diversity of species, occupying several niches, as extensive cultures (low intensity, low management) within the same pond. The "Integrated" in IMTA refers to the more intensive cultivation of the different species in proximity of each other, connected by nutrient and energy transfer through water, but not necessarily right at the same location.

Ideally, the biological and chemical processes in an IMTA system should balance. This is achieved through the appropriate selection and proportions of different species providing different ecosystem functions. The co-cultured species should be more than just biofilters; they should also be harvestable crops of commercial value.[18] A working IMTA system should result in greater production for the overall system, based on mutual benefits to the co-cultured species and improved ecosystem health, even if the individual production of some of the species is lower compared to what could be reached in monoculture practices over a short term period.[19]

Sometimes the more general term "Integrated Aquaculture" is used to describe the integration of monocultures through water transfer between organisms.[19] For all intents and purposes however, the terms "IMTA" and "integrated aquaculture" differ primarily in their degree of descriptiveness. These terms are sometimes interchanged. Aquaponics, fractionated aquaculture, IAAS (integrated agriculture-aquaculture systems), IPUAS (integrated peri-urban-aquaculture systems), and IFAS (integrated fisheries-aquaculture systems) may also be considered variations of the IMTA concept.

[edit] Mariculture

Main article: Mariculture

Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, an enclosed section of the ocean, or in tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish, prawns, or oysters in saltwater ponds. Non-food products produced by mariculture include: fish meal, nutrient agar, jewelries (e.g. cultured pearls), and cosmetics.

[edit] Shrimp farming

Main article: Shrimp farm

A shrimp farm is an aquaculture business for the cultivation of marine shrimp for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the U.S., Japan and Western Europe. The total global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9,000 million U.S. dollars. About 75% of farmed shrimp is produced in Asia, in particular in China and Thailand. The other 25% is produced mainly in Latin America, where Brazil is the largest producer. The largest exporting nation is Thailand.

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

[edit] Types of fish in aquaculture

Mirgala, Rohita, Lates calcrifer (sea bass), Murrels

[edit] See also

[edit] Notes

  1. ^ American Heritage Definition of Aquaculture
  2. ^ Peter Neushul, Seaweed for War: California's World War I kelp industry, Technology and Culture 30 (July 1989), 561-583.
  3. ^ Milner, James W. (1874). "The Progress of Fish-culture in the United States". United States Commission of Fish and Fisheries Report of the Commissioner for 1872 and 1873. 535 – 544 (http://penbay.org/cof/cof_1872_1873.html)
  4. ^ David Suzuki Foundation: Open-net-cage fish farming
  5. ^ a b c d e FAO (2006) The State of World Fisheries and Aquaculture (SOPHIA)
  6. ^ Wired 12.05: The Bluewater Revolution
  7. ^ washingtonpost.com: Fish Farming's Bounty Isn't Without Barbs
  8. ^ The State of World Fisheries and Aquaculture (SOFIA) 2004
  9. ^ Diamond, Jared. Collapse: How societies choose to fail or succeed. Viking Press, 2005. pgs. 479-485
  10. ^ Swiss WWF Factsheet, Page 7, Heading "Fische und Meeresfrüchte aus Zuchten"
  11. ^ Costa-Pierce, B.A., Author/Editor. 2002. Ecological Aquaculture. Blackwell Science, Oxford, UK.
  12. ^ a b Chopin T, Buschmann AH, Halling C, Troell M, Kautsky N, Neori A, Kraemer GP, Zertuche-Gonzalez JA, Yarish C and Neefus C. 2001. Integrating seaweeds into marine aquaculture systems: a key toward sustainability. Journal of Phycology 37: 975-986.
  13. ^ "Rice, M.A. 2008. Environmental impacts of shellfish aquaculture". http://www.nrac.umd.edu/files/Factsheets/105-Environmental%20effects.pdf. 
  14. ^ "Aquaculture: Issues and Opportunities for Sustainable Production and Trade, published by ITCSD in July 2006"
  15. ^ "Pew Oceans Commission report on Aquaculture"
  16. ^ New, M. B.: Farming Freshwater Prawns; FAO Fisheries Technical Paper 428, 2002. ISSN 0429-9345.
  17. ^ Data extracted from the FAO Fisheries Global Aquaculture Production Database for freshwater crustaceans. The most recent data sets are for 2003 and sometimes contain estimates. Accessed June 28, 2005.
  18. ^ a b Chopin T. 2006. Integrated multi-trophic aquaculture. What it is, and why you should care… and don’t confuse it with polyculture. Northern Aquaculture, Vol. 12, No. 4, July/August 2006, pg. 4.
  19. ^ a b Neori A, Chopin T, Troell M, Buschmann AH, Kraemer GP, Halling C, Shpigel M and Yarish C. 2004. Integrated aquaculture: rationale, evolution and state of the art emphasizing seaweed biofiltration in modern mariculture. Aquaculture 231: 361-391.

[edit] References

[edit] Further reading

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