Aquaculture, also known as
aquafarming, is the farming of aquatic organisms such as
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
,
crustaceanCrustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, molluscs and
aquatic plantAquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
s. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with
commercial fishingCommercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
, which is the harvesting of wild fish.
MaricultureMariculture 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,...
refers to aquaculture practised in marine environments.
The reported output from global aquaculture operations would supply one half of the fish and shellfish that is directly consumed by humans, however there are issues about the reliability of the reported figures. Further, in current aquaculture practice, products from several pounds of wild fish are used to produce one pound of a piscivorous fish like
salmonSalmon, along with carp, are the two most important fish groups in aquaculture. In 2007, the aquaculture of salmon and salmon trout was worth US$10.7 billion. The most commonly farmed salmon is the Atlantic salmon. Other commonly farmed fish groups include tilapia, catfish, sea bass, bream and...
.
Particular kinds of aquaculture include
fish farmingFish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
,
shrimp farmA shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing,
oyster farmingOyster farming is an aquaculture practice in which oysters are raised for human consumption. Oyster farming most likely developed in tandem with pearl farming, a similar practice in which oysters are farmed for the purpose of developing pearls...
,
algacultureAlgaculture 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...
(such as
seaweed farmingSeaweed farming is the practice of cultivating and harvesting seaweed. In its most simple form, it consists of the management of naturally found batches...
), and the cultivation of ornamental fish. Particular methods include
aquaponicsAquaponics is a sustainable food production system that combines a traditional aquaculture with hydroponics in a symbiotic environment. In the aquaculture, effluents accumulate in the water, increasing toxicity for the fish...
, which integrates fish farming and plant farming.
History
The indigenous
GunditjmaraGunditjmara, or Gundidj for short, are an Indigenous Australian group from western Victoria . Their neighbours to the west were the Buandig people, to the north the Jardwadjali and Djab wurrung peoples, and in the east the Girai wurrung people.The name may also be spelt Gournditch-Mara...
people in
VictoriaVictoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
,
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
may have raised eels as early as 6000 BC. There is evidence that they developed about 100 square kilometres (38.6 sq mi) of volcanic
floodplainA floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s in the vicinity of Lake Condah into a complex of channels and
damA dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s, that they used woven traps to capture
eelEels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
s, and that capturing and smoking eels supported them year round.
Aquaculture was operating in
ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
circa 2500 BC. When the waters subsided after
riverA river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
floodA flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
s, some fishes, mainly
carpThe Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive...
, were trapped in lakes. Early aquaculturists fed their brood using
nymphsIn biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
and silkworm feces, and ate them. A fortunate
geneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
tic
mutationIn molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
of
carpThe Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive...
led to the emergence of
goldfishThe goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....
during the
Tang DynastyThe Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...
.
JapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese cultivated
seaweedSeaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
by providing
bambooBamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
poles and, later, nets and
oysterThe word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
shells to serve as anchoring surfaces for spores.
RomansAncient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
bred fish in ponds.
In central
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, early
ChristianA Christian is a person who adheres to Christianity, an Abrahamic, monotheistic religion based on the life and teachings of Jesus of Nazareth as recorded in the Canonical gospels and the letters of the New Testament...
monasteriesMonastery denotes the building, or complex of buildings, that houses a room reserved for prayer as well as the domestic quarters and workplace of monastics, whether monks or nuns, and whether living in community or alone .Monasteries may vary greatly in size – a small dwelling accommodating only...
adopted Roman aquacultural practices. Aquaculture spread in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
during the
Middle AgesThe Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
, since away from the seacoasts and the big rivers, fish were scarce/expensive. Improvements in transportation during the 19th century made fish easily available and inexpensive, even in inland areas, making aquaculture less popular.
HawaiiansNative Hawaiians refers to the indigenous Polynesian people of the Hawaiian Islands or their descendants. Native Hawaiians trace their ancestry back to the original Polynesian settlers of Hawaii.According to the U.S...
constructed oceanic
fish pondA fish pond, or fishpond, is a controlled pond, artificial lake, or reservoir that is stocked with fish and is used in aquaculture for fish farming, or is used for recreational fishing or for ornamental purposes...
s (see
Hawaiian aquacultureThe Hawaiian people practiced aquaculture through development of fish ponds , the most advanced fish husbandry among the original peoples of the Pacific. These fishponds were typically shallow areas of a reef flat surrounded by a low lava rock wall built out from the shore...
). A remarkable example is a fish pond dating from at least 1,000 years ago, at Alekoko. Legend says that it was constructed by the mythical
MenehuneIn Hawaiian mythology, the Menehune [pronounced meh-neh-HOO-neh] are said to be a people, sometimes described as dwarfs in size, who live in the deep forests and hidden valleys of the Hawaiian Islands, far from the eyes of normal humans. Their favorite food is the maia , but they also like...
dwarf people.
In 1859 Stephen Ainsworth of
West Bloomfield, New YorkWest Bloomfield is a town in Ontario County, New York, USA. The population was 2,549 at the 2000 census.The Town of West Bloomfield is on the county's western border and is south of the City of Rochester.- History :...
, began experiments with
brook troutThe brook trout, Salvelinus fontinalis, is a species of fish in the salmon family of order Salmoniformes. In many parts of its range, it is known as the speckled trout or squaretail. A potamodromous population in Lake Superior are known as coaster trout or, simply, as coasters...
. By 1864 Seth Green had established a commercial fish hatching operation at Caledonia Springs, near
Rochester, New YorkRochester is a city in Monroe County, New York, south of Lake Ontario in the United States. Known as The World's Image Centre, it was also once known as The Flour City, and more recently as The Flower City...
. By 1866, with the involvement of Dr. W. W. Fletcher of
Concord, MassachusettsConcord is a town in Middlesex County, Massachusetts, in the United States. As of the 2010 census, the town population was 17,668. Although a small town, Concord is noted for its leading roles in American history and literature.-History:...
, artificial fish hatcheries were under way in both
CanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. When the
Dildo IslandDildo Island is an island in the Canadian province of Newfoundland and Labrador. It is the largest of three islands located at the entrance to Dildo Arm in the bottom of Trinity Bay, off the coast of the neighboring town of Dildo....
fish hatchery opened in Newfoundland in 1889, it was the largest and most advanced in the world.
CaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
ns harvested wild
kelpKelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
and attempted to manage supply circa 1900, later labeling it a wartime resource.
Definition
According to the
FAOFão is a town in Esposende Municipality in Portugal....
, aquaculture "is understood to mean the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants. Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated."
21st century practice
About 430 (97%) of the
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
cultured as of 2007 were domesticated during the 20th century, of which an estimated 106 came in the decade to 2007. Given the long-term importance of agriculture, it is interesting to note that to date only 0.08% of known land plant species and 0.0002% of known land animal species have been domesticated, compared with 0.17% of known marine plant species and 0.13% of known marine animal species. Domestication typically involves about a decade of scientific research. Domesticating aquatic species involve fewer risks to humans than land animals, which took a large toll in human lives. Most major human diseases originated in domesticated animals. through diseases such as
smallpoxSmallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple"...
and
diphtheriaDiphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
, that like most infectious diseases, move to humans from animals. No human
pathogenA pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s of comparable virulence have yet emerged from marine species.
Harvest stagnation in wild fisheries and
overexploitationOverexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Sustained overexploitation can lead to the destruction of the resource...
of popular marine species, combined with a growing demand for high quality protein encourages aquaculturists to domesticate other marine species.
Production volume
In 2004, the total world production of fisheries was 140 million
tonneThe tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s of which aquaculture contributed 45 million tonnes, about one third. The growth rate of worldwide aquaculture has been sustained and rapid, averaging about 8 percent per annum for over thirty years, while the take from wild fisheries has been essentially flat for the last decade. The aquaculture market reached $86 billion in 2009.
| Average annual percentage growth for different species groups |
| Time period |
Crustaceans |
Molluscs |
Freshwater
fish |
Diadromous
fish |
Marine
fish |
Overall |
| 1970–2004 |
18.9 |
7.7 |
9.3 |
7.3 |
10.5 |
8.8 |
| 1970–1980 |
23.9 |
5.6 |
6.0 |
6.5 |
14.1 |
6.2 |
| 1980–1990 |
24.1 |
7.0 |
13.1 |
9.4 |
5.3 |
10.8 |
| 1990–2000 |
9.1 |
11.6 |
10.5 |
6.5 |
12.5 |
10.5 |
| 2000–2004 |
19.2 |
5.3 |
5.2 |
5.8 |
9.6 |
6.3 |
| Major species groups in 2004 |
| Species group |
Million tonne The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s |
| Freshwater fish Freshwater fish are fish that spend some or all of their lives in freshwater, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity...
es |
23.87 |
| Molluscs |
13.93 |
| Aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
s |
13.24 |
| Diadromous fishes |
3.68 |
CrustaceanCrustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s |
2.85 |
| Marine fishes |
1.45 |
| Other aquatic animal An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
s |
0.38 |
| Top ten species groups in 2004 |
| Species group |
Million tonne The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s |
CarpCarp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain...
s and other cyprinidThe family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...
s |
18.30 |
OysterThe word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s |
4.60 |
ClamThe word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, cocklesCockle is the common name for a group of small, edible, saltwater clams, marine bivalve molluscs in the family Cardiidae.Various species of cockles live in sandy sheltered beaches throughout the world....
, ark shells |
4.12 |
| Miscellaneous freshwater fish Freshwater fish are fish that spend some or all of their lives in freshwater, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity...
es |
3.74 |
ShrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, prawnPrawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s |
2.48 |
SalmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
s, troutTrout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
s, smelts |
1.98 |
MusselThe common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s |
1.86 |
TilapiaTilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
s and other cichlidCichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
s |
1.82 |
ScallopA scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
s, pectens |
1.17 |
| Miscellaneous marine molluscs |
1.07 |
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 1900000 tonnes (1,869,986.7 LT) to nearly 23000000 tonnes (22,636,681.3 LT). In 2005, China accounted for 70% of world production. Aquaculture is also currently one of the fastest growing areas of food production in the U.S.
| Top ten aquaculture producers in 2004 |
| Country |
Million tonne The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s |
ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
|
30.61 |
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
|
2.47 |
VietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
|
1.20 |
ThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
|
1.17 |
IndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
|
1.05 |
BangladeshBangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
|
0.91 |
JapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
|
0.78 |
ChileChile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
|
0.67 |
NorwayNorway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
|
0.64 |
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
|
0.61 |
| Other countries |
5.35 |
| Total |
45.47 |
Approximately 90% of all U.S. shrimp consumption is farmed and imported. In recent years
salmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
aquaculture has become a major export in southern
ChileChile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, especially in
Puerto MonttPuerto Montt is a port city and commune in southern Chile, located at the northern end of the Reloncaví Sound in the Llanquihue Province, Los Lagos Region. The commune spans an area of and had a population of 175,938 in 2002. It is located 1,055 km to the south of the capital, Santiago...
, Chile's fastest-growing city.
Over reporting
China overwhelmingly dominates the world in reported aquaculture output. They report a total output which is double that of the rest of the world put together. However, there are issues with the accuracy of China's returns.
In 2001, the fisheries scientists Reg Watson and
Daniel PaulyDaniel Pauly is a French-born marine biologist, well-known for his work in studying human impacts on global fisheries. He is a professor and the project leader of the Sea Around Us Project at the Fisheries Centre at the University of British Columbia. He also served as Director of the Fisheries...
expressed concerns in a letter to
Nature, that China was over reporting its catch from wild fisheries in the 1990s. They said that made it appear that the global catch since 1988 was increasing annually by 300,000 tonnes, whereas it was really shrinking annually by 350,000 tonnes. Watson and Pauly suggested this may be related to China policies where state entities that monitor the economy are also tasked with increasing output. Also, until recently, the promotion of Chinese officials was based on production increases from their own areas.
China disputes this claim. The official
Xinhua News AgencyThe Xinhua News Agency is the official press agency of the government of the People's Republic of China and the biggest center for collecting information and press conferences in the PRC. It is the largest news agency in the PRC, ahead of the China News Service...
quoted Yang Jian, director general of the Agriculture Ministry's Bureau of Fisheries, as saying that China's figures were "basically correct". However, the
FAOFão is a town in Esposende Municipality in Portugal....
accepts there are issues with the reliability of China's statistical returns, and currently treats data from China, including the aquaculture data, apart from the rest of the world.
Mariculture
MaricultureMariculture 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,...
is the term used for the cultivation of marine organisms in
seawaterSeawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
, usually in sheltered coastal waters. In particular, the farming of marine fish is an example of mariculture, and so also is the farming of marine crustaceans (such as
shrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s), molluscs (such as oysters) and seaweed.
Integrated
Integrated Multi-Trophic AquacultureIntegrated multi-trophic aquaculture provides the by-products, including waste, from one aquatic species as inputs for another...
(IMTA) is a practice in which the by-products (wastes) from one species are recycled to become inputs (
fertilizerFertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
s,
foodFood is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
) for another. Fed aquaculture (for example,
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
,
shrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
) is combined with inorganic extractive (for example,
seaweedSeaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
) and organic extractive (for example,
shellfishShellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
) aquaculture to create balanced systems for environmental sustainability (biomitigation), economic stability (product diversification and risk reduction) and social acceptability (better management practices).
"Multi-Trophic" refers to the incorporation of
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
from different
trophicThe trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism...
or nutritional levels in the same system. This is one potential distinction from the age-old practice of aquatic
polyculturePolyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...
, 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
synergisticSynergy may be defined as two or more things functioning together to produce a result not independently obtainable.The term synergy comes from the Greek word from , , meaning "working together".-Definitions and usages:...
benefits, which could potentially lead to significant shifts in the
ecosystemAn ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. Some traditional polyculture systems may, in fact, incorporate a greater diversity of species, occupying several
nichesIn ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
, 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.
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 are typically more than just biofilters; they are harvestable crops of commercial value. A working IMTA system can result in greater total production based on mutual benefits to the co-cultured species and improved ecosystem health, even if the production of individual species is lower than in a
monocultureMonoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...
over a short term period.
Sometimes the term "Integrated Aquaculture" is used to describe the integration of monocultures through water transfer. For all intents and purposes however, the terms "IMTA" and "integrated aquaculture" differ only in their degree of descriptiveness.
AquaponicsAquaponics is a sustainable food production system that combines a traditional aquaculture with hydroponics in a symbiotic environment. In the aquaculture, effluents accumulate in the water, increasing toxicity for the fish...
, fractionated aquaculture, IAAS (integrated agriculture-aquaculture systems), IPUAS (integrated peri-urban-aquaculture systems), and IFAS (integrated fisheries-aquaculture systems) are other variations of the IMTA concept.
Netting materials
Various materials, including
nylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
,
polyesterPolyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
,
polypropylenePolypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
,
polyethylenePolyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
, plastic-coated welded
wireA wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
,
rubberNatural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
, patented
ropeA rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...
products (Spectra, Thorn-D, Dyneema), galvanized steel and
copperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
are used for netting in aquaculture fish enclosures around the world. All of these materials are selected for a variety of reasons, including design feasibility, material strength, cost, and corrosion resistance.
Recently, copper alloys have become important netting materials in aquaculture because they are antimicrobial (i.e., they destroy
bacteriaBacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, viruses, fungi,
algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, and other microbes) and they therefore prevent
biofoulingBiofouling or biological fouling is the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures.-Impact:...
(i.e., the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae, tubeworms, barnacles, mollusks, and other organisms). By inhibiting microbial growth, copper alloy aquaculture cages avoid costly net changes that are necessary with other materials. The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive.
Fish
The farming of fish is the most common form of aquaculture. It involves raising fish commercially in tanks, ponds, or ocean enclosures, usually for food. A facility that releases juvenile fish into the wild for recreational
fishingFishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
or to supplement a species' natural numbers is generally referred to as a fish
hatcheryA hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish or poultry. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled conditions; alternatively, it may be for economic reasons A hatchery is a...
. Fish species raised by fish farms include
salmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
,
bigeye tunaThe bigeye tuna, Thunnus obesus, is an important food fish and prized recreational game fish. It is a true tuna of the genus Thunnus, belonging to the wider mackerel family Scombridae....
,
carpCarp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain...
,
tilapiaTilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
,
catfishCatfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
and
codCod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
.
In the Mediterranean, young bluefin tuna are netted at sea and towed slowly towards the shore. They are then interned in offshore pens where they are further grown for the market. In 2009, researchers in
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
managed for the first time to coax tuna (
Southern bluefinThe southern bluefin tuna, Thunnus maccoyii, is a tuna of the family Scombridae found in open southern hemisphere waters of all the world's oceans mainly between 30°S and 50°S, to nearly 60°S...
) to breed in landlocked tanks.
Crustaceans
Commercial
shrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
farming began in the 1970s, and production grew steeply thereafter. Global production reached more than 1600000 tonnes (1,574,725.7 LT) in 2003, representing a value of nearly 9,000 million
U.S. dollarsThe United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
. About 75% of farmed shrimp is produced in
AsiaAsia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, in particular in
ChinaChina , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
and
ThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. The other 25% is produced mainly in
Latin AmericaLatin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
, where
BrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
is the largest producer. Thailand is the largest exporter.
Shrimp farming has changed from its traditional, small-scale form in
Southeast AsiaSoutheast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
into a global industry. Technological advances have led to ever higher densities per unit area, and
broodstockBroodstock, or broodfish, are a group of mature individuals used in aquaculture for breeding purposes. Broodstock can be a population of animals maintained in captivity as a source of replacement for, or enhancement of, seed and fry numbers. These are generally kept in ponds or tanks in which...
is shipped worldwide. Virtually all farmed shrimp are penaeids (i.e., shrimp of the
familyIn biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
PenaeidaePenaeidae is a family of prawns, although they are often referred to as penaeid shrimp. It contains many species of economic importance, such as the tiger prawn , whiteleg shrimp, Atlantic white shrimp and Indian prawn. Many prawns are the subject of commercial fishery, and farming, both in marine...
), and just two species of shrimp, the
Pacific white shrimpWhiteleg shrimp , also known as Pacific white shrimp, is a variety of prawn of the eastern Pacific Ocean commonly caught or farmed for food.-Description:...
and the giant tiger prawn, account for about 80% of all farmed shrimp. These industrial
monocultureMonoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...
s are very susceptible to
diseaseA disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
, which has decimated shrimp populations across entire regions. Increasing
ecologicalEcology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
problems, repeated disease outbreaks, and pressure and criticism from both
NGOsA non-governmental organization is a legally constituted organization created by natural or legal persons that operates independently from any government. The term originated from the United Nations , and is normally used to refer to organizations that do not form part of the government and are...
and consumer countries led to changes in the industry in the late 1990s and generally stronger regulations. In 1999, governments, industry representatives, and environmental organizations initiated a program aimed at developing and promoting more
sustainable farmingSustainable agriculture is the practice of farming using principles of ecology, the study of relationships between organisms and their environment...
practices.
Freshwater prawn farmA 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...
ing shares many characteristics with, including many problems with marine
shrimp farmA shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing. Unique problems are introduced by the developmental life cycle of the main species, the
giant river prawnMacrobrachium rosenbergii, also known as the giant river prawn, giant freshwater prawn, Malaysian prawn, freshwater scampi , or cherabin, is a species of freshwater shrimp native to the Indo-Pacific region,...
.
The global annual production of freshwater prawns (excluding
crayfishCrayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
and
crabTrue crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s) in 2003 was about 280,000
tonneThe tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s of which China produced 180,000 tonnes followed by India and Thailand with 35,000 tonnes each. Additionally, China produced about 370,000 tonnes of Chinese river crab.
Molluscs
AbaloneAbalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...
farming began in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, this industry has become increasingly successful. Over-fishing and
poachingPoaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
have reduced wild populations to the extent that farmed abalone now supplies most abalone meat.
Echinoderms
Commercially harvested
echinodermEchinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....
s include
sea cucumberSea cucumbers are echinoderms from the class Holothuroidea.They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. There are a number of holothurian species and genera, many of which are targeted...
s and
sea urchinSea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
s. In China,
sea cucumberSea cucumbers are echinoderms from the class Holothuroidea.They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. There are a number of holothurian species and genera, many of which are targeted...
s are farmed in artificial ponds as large as 1000 acres (404.7 ha).
Algae
Microalgae, also referred to as
phytoplanktonPhytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
,
microphytesMicrophytes or microalgae are microscopic algae, typically found in freshwater and marine systems. They are unicellular species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few micrometers to a few hundreds of micrometers. Unlike higher...
, or planktonic algae constitute the majority of cultivated
algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
.
Macroalgae, commonly known as
seaweedSeaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
, also have many commercial and industrial uses, but due to their size and specific requirements, they are not easily cultivated on a large scale and are most often taken in the wild.
Issues
Aquaculture can be more environmentally damaging than exploiting
wild fisheriesA fishery is an area with an associated fish or aquatic population which is harvested for its commercial value. Fisheries can be marine or freshwater. They can also be wild or farmed. This article is an overview of the habitats occupied by the worlds' wild fisheries, and the human impacts on those...
on a local area basis but has considerably less impact on the global environment on a per kg of production basis. Local concerns include waste handling, side-effects of
antibioticAn antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s, competition between farmed and wild animals, and using other fish to feed more marketable carnivorous fish. However, research and commercial feed improvements during the 1990s & 2000s have lessened many of these.
Fish waste is organic and composed of nutrients necessary in all components of aquatic food webs. In-ocean aquaculture often produces much higher than normal fish waste concentrations. The waste collects on the ocean bottom, damaging or eliminating bottom-dwelling life. Waste can also decrease dissolved oxygen levels in the water column, putting further pressure on wild animals.
Fish oils
The nutritional value of farm-raised
tilapiaTilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
may be compromised due to the amount of
cornMaize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
included in the feed. Corn contains short chain omega-6
fatty acidIn chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s that contribute to the buildup of these materials in the fish. "Ratios of long-chain omega-6 to long-chain omega-3, AA to EPA respectively, in tilapia averaged about 11:1, compared to much less than 1:1 (indicating more EPA than AA) in both salmon and trout." The US produced 1.5 million
tonThe ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...
s of tilapia in 2005, with 2.5 million projected by 2010 . Widespread publicity encouraging fish consumption has led to increases in tilapia consumption by those with lower incomes who are trying to eat a balanced diet. The lower amounts of omega-3 and the higher ratios of omega-6 compounds in farmed tilapia raise questions of the health benefits of consuming this fish.
Adequate diets for salmon and other carnivorous fish can be formulated from protein sources such as soy, although soy-based diets may also change in the balance between omega-6 and omega-3 fatty acids.
Impacts on wild fish
Salmon farming currently leads to a high demand for wild
forage fishForage fish, also called prey fish or bait fish, are small fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding...
. Fish do not actually produce omega-3 fatty acids, but instead accumulate them from either consuming microalgae that produce these fatty acids, as is the case with forage fish like
herringHerring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
and sardines, or, as is the case with fatty
predatory fishPredatory fish are fish that predate upon other fish or animals. Some predatory fish include perch, muskie , pike, walleye, salmon.Levels of large predatory fish in the global oceans are estimated to be about 10% of their pre-industrial levels...
, like salmon, by eating prey fish that have accumulated
omega-3 fatty acidN−3 fatty acids are essential unsaturated fatty acids with a double bond starting after the third carbon atom from the end of the carbon chain....
s from microalgae. To satisfy this requirement, more than 50 percent of the world
fish oilFish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid , and docosahexaenoic acid , precursors of certain eicosanoids that are known to reduce inflammation throughout the body, and are thought to have many health benefits.Fish do not...
production is fed to farmed salmon.
In addition, as carnivores, salmon require large nutritional intakes of protein, protein which is often supplied to them in the form of forage fish. Consequently, farmed salmon consume more wild fish than they generate as a final product. To produce one pound of farmed salmon, products from several pounds of wild fish are fed to them. As the salmon farming industry expands, it requires more wild forage fish for feed, at a time when seventy five percent of the worlds monitored fisheries are already near to or have exceeded their
maximum sustainable yieldIn population ecology and economics, maximum sustainable yield or MSY is, theoretically, the largest yield that can be taken from a species' stock over an indefinite period...
. The industrial scale extraction of wild forage fish for salmon farming then impacts the survivability of the wild predator fish who rely on them for food.
Fish can escape from coastal pens, where they can interbreed with their wild counterparts, diluting wild genetic stocks. Escaped fish can become
invasive"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
, out competing native species.
Coastal ecosystems
Aquaculture is becoming a significant threat to
coastal ecosystemsAn aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems....
. About 20 percent of mangrove forests have been destroyed since 1980, partly due to
shrimp farmA shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
ing. An extended cost–benefit analysis of the
total economic valueTotal economic value appears in environmental economics as an aggregation of the main function based values provided by a given ecosystem. Those include use and non-use values....
of shrimp aquaculture built on mangrove ecosystems found that the
externalIn economics, an externality is a cost or benefit, not transmitted through prices, incurred by a party who did not agree to the action causing the cost or benefit...
costs were much higher than the external benefits. Over four decades, 269000 hectares (664,712.9 acre) of Indonesian mangroves have been converted to shrimp farms. Most of these farms are abandoned within a decade because of the
toxinA toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
build-up and
nutrientA nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
loss.
Salmon farmsSalmon, along with carp, are the two most important fish groups in aquaculture. In 2007, the aquaculture of salmon and salmon trout was worth US$10.7 billion. The most commonly farmed salmon is the Atlantic salmon. Other commonly farmed fish groups include tilapia, catfish, sea bass, bream and...
are typically sited in pristine coastal ecosystems which they then pollute. A farm with 200,000 salmon discharges more fecal waste than a city of 60,000 people. This waste is discharged directly into the surrounding aquatic environment, untreated, often containing antibiotics and
pesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s." There is also an accumulation of
heavy metalsA heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...
on the
benthosBenthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
(seafloor) near the salmon farms, particularly
copperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
and
zincZinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
.
Genetic modification
Salmon have been genetically modified for faster growth, although they are not approved for commercial use, in the face of opposition. One study, in a laboratory setting, found that modified salmon mixed with their wild relatives were aggressive in competing, but ultimately failed.
Animal welfare
As with the farming of terrestrial animals, social attitudes influence the need for humane practices and regulations in farmed marine animals. Under the guidelines advised by the
Farm Animal Welfare CouncilThe Farm Animal Welfare Council was an independent advisory body established by the Government of Great Britain in 1979. FAWC has published its Final Report before its closure on 31 March 2011...
good animal welfare means both fitness and a sense of well being in the animal’s physical and mental state. This can be defined by the Five Freedoms:
- Freedom from hunger & thirst
- Freedom from discomfort
- Freedom from pain, disease, or injury
- Freedom to express normal behaviour
- Freedom from fear and distress
However, the controversial issue in aquaculture is whether fish and farmed marine invertebrates are actually sentient, or have the perception and awareness to experience suffering. Although no evidence of this has been found in marine invertebrates, recent studies conclude that fish do have the necessary receptors (nociceptors) to sense noxious stimuli and so are likely to experience states of pain, fear and stress. Consequently, welfare in aquaculture is directed at vertebrates; finfish in particular.
Common welfare concerns
Welfare in aquaculture can be impacted by a number of issues such as stocking densities, behavioural interactions, disease and parasitism. A major problem in determining the cause of impaired welfare is that these issues are often all interrelated and influence each other at different times.
Optimal stocking density is often defined by the
carrying capacityThe carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
of the stocked environment and the amount of individual space needed by the fish, which is very species specific. Although behavioural interactions such as
shoalingIn biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
may mean that high stocking densities are beneficial to some species, in many cultured species high stocking densities may be of concern. Crowding can constrain normal swimming behaviour, as well as increase aggressive and competetive behaviours such as cannibalism, feed competition, territoriality and dominance/subordination hierarchies. This potentially increases the risk of tissue damage due to abrasion from fish-to-fish contact or fish-to-cage contact. Fish can suffer reductions in food intake and
food conversion efficiencyIn animal husbandry, feed conversion ratio , feed conversion rate, or feed conversion efficiency , is a measure of an animal's efficiency in converting feed mass into increased body mass....
. In addition, high stocking densities can result in water flow being insufficient, creating inadequate oxygen supply and waste product removal. Dissolved oxygen is essential for fish respiration and concentrations below critical levels can induce stress and even lead to asphyxiation. Ammonia, a nitrogen excretion product, is highly toxic to fish at accumulated levels, particularly when oxygen concentrations are low.
Many of these interactions and effects cause stress in the fish, which can be a major factor in facilitating fish disease. For many parasites, infestation depends on the host’s degree of mobility, the density of the host population and vulnerability of the host’s defence system. Sea lice are the primary parasitic problem for finfish in aquaculture, high numbers causing widespread skin erosion and haemorrhaging, gill congestion,and increased mucus production. There are also a number of prominent viral and bacterial pathogens that can have severe effects on internal organs and nervous systems.
Improving welfare
The key to improving welfare of marine cultured organisms is to reduce stress to a minimum, as prolonged or repeated stress can cause a range of adverse effects. Attempts to minimise stress can occur throughout the culture process. During grow out it is important to keep stocking densities at appropriate levels specific to each species, as well as separating size classes and grading to reduce aggressive behavioural interactions. Keeping nets and cages clean can assist positive water flow to reduce the risk of water degradation.
Not surprisingly disease and parasitism can have a major affect on fish welfare and it is important for farmers not only to manage infected stock but also to apply disease prevention measures. However, prevention methods, such as vaccination, can also induce stress because of the extra handling and injection. Other methods include adding antibiotics to feed, adding chemicals into water for treatment baths and biological control, such as using
cleaner wrasseCleaner fish are fish that provide a service to other fish species by removing dead skin and ectoparasites. This is an example of mutualism, an ecological interaction that benefits both parties involved. A wide variety of fishes have been observed to display cleaning behaviors including wrasses,...
to remove lice from farmed salmon.
Many steps are involved in transport, including capture, food deprivation to reduce faecal contamination of transport water, transfer to transport vehicle via nets or pumps, plus transport and transfer to the delivery location. During transport water needs to be maintained to a high quality, with regulated temperature, sufficient oxygen and minimal waste products. In some cases anaesthetics may be used in small doses to calm fish before transport.
Prospects
Global wild fisheries are in decline, with valuable habitat such as
estuariesAn estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
in critical condition. The aquaculture or farming of piscivorous fish, like
salmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
, does not help the problem because they need to eat products from other fish, such as
fish mealFish meal, or fishmeal, is a commercial product made from both whole fish and the bones and offal from processed fish. It is a brown powder or cake obtained by rendering pressing the cooked whole fish or fish trimmings to remove most of the fish oil and water, and then ground...
and
fish oilFish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid , and docosahexaenoic acid , precursors of certain eicosanoids that are known to reduce inflammation throughout the body, and are thought to have many health benefits.Fish do not...
. Studies have shown that
salmon farmingSalmon, along with carp, are the two most important fish groups in aquaculture. In 2007, the aquaculture of salmon and salmon trout was worth US$10.7 billion. The most commonly farmed salmon is the Atlantic salmon. Other commonly farmed fish groups include tilapia, catfish, sea bass, bream and...
has major negative impacts on wild salmon, as well as the
forage fishForage fish, also called prey fish or bait fish, are small fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding...
that need to be caught to feed them. Fish that are higher on the
food chainThe trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism...
are less efficient sources of food energy.
Apart from fish and shrimp, some aquaculture undertakings, such as seaweed and filter-feeding bivalve mollusks like oysters,
clamsCLaMS is a modular chemistry transport model system developed at Forschungszentrum Jülich, Germany. CLaMS was first described by McKenna et al. and was expanded into three dimensions by Konopka et al....
, mussels and scallops, are relatively benign and even environmentally restorative. Filter-feeders filter pollutants as well as nutrients from the water, improving water quality. Seaweeds extract nutrients such as inorganic nitrogen and
phosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
directly from the water, and filter-feeding mollusks can extract nutrients as they feed on particulates, such as
phytoplanktonPhytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
and
detritusDetritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
.
Some profitable aquaculture cooperatives promote sustainable practices. New methods lessen the risk of biological and chemical
pollutionPollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
through minimizing fish stress, fallowing netpens, and applying
Integrated Pest ManagementIntegrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
.
VaccineA vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
s are being used more and more to reduce
antibioticAn antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
use for disease control.
Onshore recirculating aquaculture systems, facilities using
polyculturePolyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...
techniques, and properly sited facilities (for example, offshore areas with strong currents) are examples of ways to manage negative environmental effects.
Recirculating aquaculture systems (RAS) recycle water by circulating it through filters to remove fish waste and food and then recirculating it back into the tanks. This saves water and the waste gathered can be used in
compostCompost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Compost is a key ingredient in organic farming. At its most essential, the process of composting requires simply piling up waste outdoors and waiting for the materials to break down from anywhere...
or, in some cases, could even be treated and used on land. While RAS was developed with freshwater fish in mind, scientist associated with the
Agricultural Research ServiceThe Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...
have found a way to rear saltwater fish using RAS in low-salinity waters. Although saltwater fish are raised in off-shore cages or caught with nets in water that typically has a salinity of 35 parts per thousand (ppt), scientists were able to produce healthy pompano, a saltwater fish, in tanks with a salinity of only 5 ppt. Commercializing low-salinity RAS are predicted to have positive environmental and economical effects. Unwanted nutrients from the fish food would not be added to the ocean and the risk of transmitting diseases between wild and farm-raised fish would greatly be reduced. The price of expensive saltwater fish, such as the pompano and combia used in the experiments, would be reduced. However, before any of this can be done researchers must study every aspect of the fish’s lifecycle, including the amount of ammonia and nitrate the fish will tolerate in the water, what to feed the fish during each stage of its lifecycle, the stocking rate that will produce the healthiest fish, etc.
See also
- Aquaponics
Aquaponics is a sustainable food production system that combines a traditional aquaculture with hydroponics in a symbiotic environment. In the aquaculture, effluents accumulate in the water, increasing toxicity for the fish...
- Agroecology
Agroecology is the application of ecological principles to the production of food, fuel, fiber, and pharmaceuticals. The term encompasses a broad range of approaches, and is considered "a science, a movement, [and] a practice."...
- Copper alloys in aquaculture
Recently, copper alloys have become important netting materials in aquaculture . Various other materials including nylon, polyester, polypropylene, polyethylene, plastic-coated welded wire, rubber, patented twine products , and galvanized steel are also used for netting in aquaculture fish...
- Fisheries science
Fisheries science is the academic discipline of managing and understanding fisheries. It is a multidisciplinary science, which draws on the disciplines of oceanography, marine biology, marine conservation, ecology, population dynamics, economics and management to attempt to provide an integrated...
- Fish hatchery
A fish hatchery is a "place for artificial breeding, hatching and rearing through the early life stages of animals, finfish and shellfish in particular". Hatcheries produce larval and juvenile fish primarily to support the aquaculture industry where they are transferred to on-growing systems...
- Industrial aquaculture
Further reading
External links