Fish farming

Koi farming indoors in Israel
Salmon farming in the sea (mariculture) at Loch Ainort, Isle of Skye

Fish farming or pisciculture involves raising fish commercially in tanks or enclosures, usually for food. It is the principal form of aquaculture, while other methods may fall under mariculture. 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. Worldwide, the most important fish species used in fish farming are carp, tilapia, salmon, and catfish.[1]

There is an increasing demand for fish and fish protein, which has resulted in widespread overfishing in wild fisheries, China holding 62 percent of the world's fish farming practice.[2] Fish farming offers fish marketers another source. However, farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish. The global returns for fish farming recorded by the FAO in 2008 totalled 33.8 million tonnes worth about $US 60 billion.[3] In 2005, aquaculture represented 40% of the 157.5 million tons of seafood that was produced, meaning that it has become a critical part of our world's food source even though the industry is still technically in its 'infancy' and didn't really become well known until the 1970s. Because of this rise in aquaculture, there has been a rise in the per capita availability of seafood globally within the last few decades.[4]

Major species

Top 15 cultured fish species by weight in millions of tonnes, according to FAO statistics for 2013 [1]
Species Environment Tonnage (millions) Value (USD, billion)
Grass carp freshwater 5.23 6.69
Silver carp freshwater 4.59 6.13
Common carp freshwater 3.76 5.19
Nile tilapia freshwater 3.26 5.39
Bighead carp freshwater 2.90 3.72
Catla (Indian carp) freshwater 2.76 5.49
Crucian carp freshwater 2.45 2.67
Atlantic salmon marine 2.07 10.10
Roho labeo freshwater 1.57 2.54
Milkfish freshwater 0.94 1.71
Rainbow trout freshwater, brackish 0.88 3.80
Wuchang bream freshwater 0.71 1.16
Black carp freshwater 0.50 1.15
Northern snakehead freshwater 0.48 0.59
Amur catfish freshwater 0.41 0.55

Major categories of fish aquaculture

There are two kinds of aquaculture: extensive aquaculture based on local photosynthetical production and intensive aquaculture, in which the fish are fed with external food supply.

Extensive aquaculture

Aqua-Boy, a Norwegian live fish carrier used to service the Marine Harvest fish farms on the West coast of Scotland

Limiting for growth here is the available food supply by natural sources, commonly zooplankton feeding on pelagic algae or benthic animals, such as crustaceans and mollusks. Tilapia species filter feed directly on phytoplankton, which makes higher production possible. The photosynthetic production can be increased by fertilizing the pond water with artificial fertilizer mixtures, such as potash, phosphorus, nitrogen and micro-elements. Because most fish are carnivorous, they occupy a higher place in the trophic chain and therefore only a tiny fraction of primary photosynthetic production (typically 1%) will be converted into harvest-able fish.

Another issue is the risk of algal blooms. When temperatures, nutrient supply and available sunlight are optimal for algal growth, algae multiply their biomass at an exponential rate, eventually leading to an exhaustion of available nutrients and a subsequent die-off. The decaying algal biomass will deplete the oxygen in the pond water because it blocks out the sun and pollutes it with organic and inorganic solutes (such as ammonium ions), which can (and frequently do) lead to massive loss of fish.

An alternate option is to use a wetland system such as that of Veta La Palma.

In order to tap all available food sources in the pond, the aquaculturist will choose fish species which occupy different places in the pond ecosystem, e.g., a filter algae feeder such as tilapia, a benthic feeder such as carp or catfish and a zooplankton feeder (various carps) or submerged weeds feeder such as grass carp.

Despite these limitations significant fish farming industries use these methods. In the Czech Republic thousands of natural and semi-natural ponds are harvested each year for trout and carp. The large ponds around Trebon were built from around 1650 and are still in use.

Intensive aquaculture

Optimal water parameters for cold- and warm-water fish in intensive aquaculture[5]
Acidity pH 6-9
Arsenic <440 µg/L
Alkalinity >20 mg/L (as CaCO3)
Aluminum <0.075 mg/L
Ammonia (non-ionized) <O.O2mg/L
Cadmium <0.0005 mg/L in soft water;
<0.005 mg/L in hard water
Calcium >5 mg/L
Carbon dioxide <5–10 mg/L
Chloride >4.0 mg/L
Chlorine <0.003 mg/L
Copper <0.0006 mg/L in soft water;
<0.03 mg/L in hard water
Gas supersaturation <100% total gas pressure
(103% for salmonid eggs/fry)
(102% for lake trout)
Hydrogen sulfide <0.003 mg/L
Iron <0.1 mg/L
Lead <0.02 mg/L
Mercury <0.0002 mg/L
Nitrate <1.0 mg/L
Nitrite <0.1 mg/L
Oxygen 6 mg/L for coldwater fish
4 mg/L for warmwater fish
Selenium <0.01 mg/L
Total dissolved solids <200 mg/L
Total suspended solids <80 NTU over ambient levels
Zinc <0.005 mg/L

In these kinds of systems fish production per unit of surface can be increased at will, as long as sufficient oxygen, fresh water and food are provided. Because of the requirement of sufficient fresh water, a massive water purification system must be integrated in the fish farm. One way to achieve this is to combine hydroponic horticulture and water treatment, see below. The exception to this rule are cages which are placed in a river or sea, which supplements the fish crop with sufficient oxygenated water. Some environmentalists object to this practice.

Expressing eggs from a female rainbow trout

The cost of inputs per unit of fish weight is higher than in extensive farming, especially because of the high cost of fish feed, which must contain a much higher level of protein (up to 60%) than cattle food and a balanced amino acid composition as well. However, these higher protein level requirements are a consequence of the higher food conversion efficiency (FCR—kg of feed per kg of animal produced) of aquatic animals. Fish like salmon have an FCR around 1.1 kg of feed per kg of salmon[6] whereas chickens are in the 2.5 kg of feed per kg of chicken range. Fish do not have use energy to keep warm, eliminating a lot of carbohydrates and fats in the diet, required to provide this energy. This however may be offset by the lower land costs and the higher productions which can be obtained due to the high level of input control.

Aeration of the water is essential, as fish need a sufficient oxygen level for growth. This is achieved by bubbling, cascade flow or aqueous oxygen. Catfish, Clarias spp. can breathe atmospheric air and can tolerate much higher levels of pollutants than trout or salmon, which makes aeration and water purification less necessary and makes Clarias species especially suited for intensive fish production. In some Clarias farms about 10% of the water volume can consist of fish biomass.

The risk of infections by parasites like fish lice, fungi (Saprolegnia spp.), intestinal worms (such as nematodes or trematodes), bacteria (e.g., Yersinia spp., Pseudomonas spp.), and protozoa (such as Dinoflagellates) is similar to animal husbandry, especially at high population densities. However, animal husbandry is a larger and more technologically mature area of human agriculture and better solutions to pathogen problem exist. Intensive aquaculture does have to provide adequate water quality (oxygen, ammonia, nitrite, etc.) levels to minimize stress, which makes the pathogen problem more difficult. This means, intensive aquaculture requires tight monitoring and a high level of expertise of the fish farmer.

Controlling roes manually

Very high intensity recycle aquaculture systems (RAS), where there is control over all the production parameters, are being used for high value species. By recycling the water, very little water is used per unit of production. However, the process does have high capital and operating costs. The higher cost structures mean that RAS is only economical for high value products like broodstock for egg production, fingerlings for net pen aquaculture operations, sturgeon production, research animals and some special niche markets like live fish.[7][8]

Raising ornamental cold water fish (goldfish or koi), although theoretically much more profitable due to the higher income per weight of fish produced, has never been successfully carried out until very recently. The increased incidences of dangerous viral diseases of koi Carp, together with the high value of the fish has led to initiatives in closed system koi breeding and growing in a number of countries. Today there are a few commercially successful intensive koi growing facilities in the UK, Germany and Israel.

Some producers have adapted their intensive systems in an effort to provide consumers with fish that do not carry dormant forms of viruses and diseases.

Specific types of fish farms

Within intensive and extensive aquaculture methods, there are numerous specific types of fish farms; each has benefits and applications unique to its design.

Cage system

Giant gourami is often raised in cages in central Thailand

Fish cages are placed in lakes, bayous, ponds, rivers or oceans to contain and protect fish until they can be harvested.[9] The method is also called "off-shore cultivation[10] " when the cages are placed in the sea. They can be constructed of a wide variety of components. Fish are stocked in cages, artificially fed, and harvested when they reach market size. A few advantages of fish farming with cages are that many types of waters can be used (rivers, lakes, filled quarries, etc.), many types of fish can be raised, and fish farming can co-exist with sport fishing and other water uses.[9] Cage farming of fishes in open seas is also gaining popularity. Concerns of disease, poaching, poor water quality, etc., lead some to believe that in general, pond systems are easier to manage and simpler to start. Also, past occurrences of cage-failures leading to escapes, have raised concern regarding the culture of non-native fish species in dam or open-water cages. Even though the cage-industry has made numerous technological advances in cage construction in recent years, storms will always make the concern for escapes valid.[9]

Recently, copper alloys have become important netting materials in aquaculture. Copper alloys are antimicrobial, that is, they destroy bacteria, viruses, fungi, algae, and other microbes. In the marine environment, the antimicrobial/algaecidal properties of copper alloys prevent biofouling, which can briefly be described as the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae, tube worms, barnacles, mollusks, and other organisms.

The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive. Traditional netting involves regular and labor-intensive cleaning. In addition to its antifouling benefits, copper netting has strong structural and corrosion-resistant properties in marine environments.

Copper-zinc brass alloys are currently (2011) being deployed in commercial-scale aquaculture operations in Asia, South America and the USA (Hawaii). Extensive research, including demonstrations and trials, are currently being implemented on two other copper alloys: copper-nickel and copper-silicon. Each of these alloy types has an inherent ability to reduce biofouling, cage waste, disease, and the need for antibiotics while simultaneously maintaining water circulation and oxygen requirements. Other types of copper alloys are also being considered for research and development in aquaculture operations.

Irrigation ditch or pond systems

A row of square artificial ponds, with trees on either side
These fish-farming ponds were created as a cooperative project in a rural village.

These use irrigation ditches or farm ponds to raise fish. The basic requirement is to have a ditch or pond that retains water, possibly with an above-ground irrigation system (many irrigation systems use buried pipes with headers.)

Using this method, one can store one's water allotment in ponds or ditches, usually lined with bentonite clay. In small systems the fish are often fed commercial fish food, and their waste products can help fertilize the fields. In larger ponds, the pond grows water plants and algae as fish food. Some of the most successful ponds grow introduced strains of plants, as well as introduced strains of fish.

Control of water quality is crucial. Fertilizing, clarifying and pH control of the water can increase yields substantially, as long as eutrophication is prevented and oxygen levels stay high.Yields can be low if the fish grow ill from electrolyte stress.

Composite fish culture

The Composite fish culture system is a technology developed in India by the Indian Council of Agricultural Research in the 1970s. In this system both local and imported fish species, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them having different types of food habitats.[11][12] As a result, the food available in all the parts of the pond is used. Fish used in this system include catla and silver carp which are surface feeders, rohu a column feeder and mrigal and common carp which are bottom feeders. Other fish will also feed on the excreta of the common carp and this helps contribute to the efficiency of the system which in optimal conditions will produce 3000–6000 kg of fish per hectare per year.

One problem with such composite fish culture is that many of these fish breed only during monsoon. Even if fish seed is collected from the wild, it can be mixed with that of other species as well. So, a major problem in fish farming is the lack of availability of good-quality seed. To overcome this problem, ways have now been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish seed in desired quantities.

Integrated recycling systems

Main article: Aquaponics

One of the largest problems with freshwater pisciculture is that it can use a million gallons of water per acre (about 1 m³ of water per m²) each year. Extended water purification systems allow for the reuse (recycling) of local water.

The largest-scale pure fish farms use a system derived (admittedly much refined) from the New Alchemy Institute in the 1970s. Basically, large plastic fish tanks are placed in a greenhouse. A hydroponic bed is placed near, above or between them. When tilapia are raised in the tanks, they are able to eat algae, which naturally grow in the tanks when the tanks are properly fertilized.

The tank water is slowly circulated to the hydroponic beds where the tilapia waste feeds commercial plant crops. Carefully cultured microorganisms in the hydroponic bed convert ammonia to nitrates, and the plants are fertilized by the nitrates and phosphates. Other wastes are strained out by the hydroponic media, which doubles as an aerated pebble-bed filter.

This system, properly tuned, produces more edible protein per unit area than any other. A wide variety of plants can grow well in the hydroponic beds. Most growers concentrate on herbs (e.g. parsley and basil), which command premium prices in small quantities all year long. The most common customers are restaurant wholesalers.

Since the system lives in a greenhouse, it adapts to almost all temperate climates, and may also adapt to tropical climates. The main environmental impact is discharge of water that must be salted to maintain the fishes' electrolyte balance. Current growers use a variety of proprietary tricks to keep fish healthy, reducing their expenses for salt and waste water discharge permits. Some veterinary authorities speculate that ultraviolet ozone disinfectant systems (widely used for ornamental fish) may play a prominent part in keeping the Tilapia healthy with recirculated water.

A number of large, well-capitalized ventures in this area have failed. Managing both the biology and markets is complicated. One future development is the combination of Integrated Recycling systems with Urban Farming as tried in Sweden by the Greenfish initiative.[13][14]

Classic fry farming

This is also called a "Flow through system" [15] Trout and other sport fish are often raised from eggs to fry or fingerlings and then trucked to streams and released. Normally, the fry are raised in long, shallow concrete tanks, fed with fresh stream water. The fry receive commercial fish food in pellets. While not as efficient as the New Alchemists' method, it is also far simpler, and has been used for many years to stock streams with sport fish. European eel (Anguilla anguilla) aquaculturalists procure a limited supply of glass eels, juvenile stages of the European eel which swim north from the Sargasso Sea breeding grounds, for their farms. The European eel is threatened with extinction because of the excessive catch of glass eels by Spanish fishermen and overfishing of adult eels in, e.g., the Dutch IJsselmeer, Netherlands. As per 2005, no one has managed to breed the European eel in captivity.

Issues

The issue of feeds in fish farming has been a controversial one. Many cultured fishes (tilapia, carp, catfish, many others) require no meat or fish products in their diets. Top-level carnivores (most salmon species) depend on fish feed of which a portion is usually derived from wild caught (anchovies, menhaden, etc.). Vegetable-derived proteins have successfully replaced fish meal in feeds for carnivorous fishes, but vegetable-derived oils have not successfully been incorporated into the diets of carnivores.

Secondly, farmed fish are kept in concentrations never seen in the wild (e.g. 50,000 fish in a 2-acre (8,100 m2) area.[16]). However, fish tend also to be animals that aggregate into large schools at high density. Most successful aquaculture species are schooling species, which do not have social problems at high density. Aquaculturists tend to feel that operating a rearing system above its design capacity or above the social density limit of the fish will result in decreased growth rate and increased FCR (food conversion ratio - kg dry feed/kg of fish produced), which will result in increased cost and risk of health problems along with a decrease in profits. Stressing the animals is not desirable, but the concept of and measurement of stress must be viewed from the perspective of the animal using the scientific method.[17]

Sea lice, particularly Lepeophtheirus salmonis and various Caligus species, including Caligus clemensi and Caligus rogercresseyi, can cause deadly infestations of both farm-grown and wild salmon.[18][19] Sea lice are ectoparasites which feed on mucus, blood, and skin, and migrate and latch onto the skin of wild salmon during free-swimming, planktonic nauplii and copepodid larval stages, which can persist for several days.[20][21][22] Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice; when exposed in river estuaries containing large numbers of open-net farms, many young wild salmon are infected, and do not survive as a result.[23][24] Adult salmon may survive otherwise critical numbers of sea lice, but small, thin-skinned juvenile salmon migrating to sea are highly vulnerable. On the Pacific coast of Canada, the louse-induced mortality of pink salmon in some regions is commonly over 80%.[25]

A 2008 meta-analysis of available data shows that salmon farming reduces the survival of associated wild salmon populations. This relationship has been shown to hold for Atlantic, steelhead, pink, chum, and coho salmon. The decrease in survival or abundance often exceeds 50 percent.[26]

Diseases and parasites are the most commonly cited reasons for such decreases. Some species of sea lice have been noted to target farmed coho and Atlantic salmon.[27] Such parasites have been shown to have an effect on nearby wild fish. One place that has garnered international media attention is British Columbia's Broughton Archipelago. There, juvenile wild salmon must "run a gauntlet" of large fish farms located off-shore near river outlets before making their way to sea. It is alleged that the farms cause such severe sea lice infestations that one study predicted in 2007 a 99% collapse in the wild salmon population by 2011.[28] This claim, however, has been criticized by numerous scientists who question the correlation between increased fish farming and increases in sea lice infestation among wild salmon.[29]

Because of parasite problems, some aquaculture operators frequently use strong antibiotic drugs to keep the fish alive (but many fish still die prematurely at rates of up to 30 percent[30]). In some cases, these drugs have entered the environment. Additionally, the residual presence of these drugs in human food products has become controversial. Use of antibiotics in food production is thought to increase the prevalence of antibiotic resistance in human diseases.[31] At some facilities, the use of antibiotic drugs in aquaculture has decreased considerably due to vaccinations and other techniques.[32] However, most fish farming operations still use antibiotics, many of which escape into the surrounding environment.[33]

The lice and pathogen problems of the 1990s facilitated the development of current treatment methods for sea lice and pathogens. These developments reduced the stress from parasite/pathogen problems. However, being in an ocean environment, the transfer of disease organisms from the wild fish to the aquaculture fish is an ever-present risk.[34]

The very large number of fish kept long-term in a single location contributes to habitat destruction of the nearby areas.[35] The high concentrations of fish produce a significant amount of condensed faeces, often contaminated with drugs, which again affect local waterways. However, if the farm is correctly placed in an area with a strong current, the 'pollutants' are flushed out of the area fairly quickly. Not only does this help with the pollution problem. but water with a stronger current also aids in overall fish growth. Concern remains that resultant bacterial growth strips the water of oxygen, reducing or killing off the local marine life. Once an area has been so contaminated, the fish farms are moved to new, uncontaminated areas. This practice has angered nearby fishermen.[36]

Other potential problems faced by aquaculturists are the obtaining of various permits and water-use rights, profitability, concerns about invasive species and genetic engineering depending on what species are involved, and interaction with the United Nations Convention on the Law of the Sea.

In regards to genetically modified farmed salmon, concern has been raised over their proven reproductive advantage and how it could potentially decimate local fish populations, if released into the wild. Biologist Rick Howard [37] did a controlled laboratory study where wild fish and GMO fish were allowed to breed. The GMO fish crowded out the wild fish in spawning beds, but the offspring were less likely to survive. The colorant used to make pen-raised salmon appear rosy like their wild cousins has been linked with retinal problems in humans.[36]

Labeling

In 2005, Alaska passed legislation requiring that any genetically altered fish sold in the state be labeled.[38] In 2006, a Consumer Reports investigation revealed that farm-raised salmon is frequently sold as wild.[39]

In 2008, the US National Organic Standards Board allowed farmed fish to be labeled as organic provided less than 25% of their feed came from wild fish. This decision was criticized by the advocacy group Food & Water Watch as "bending the rules" about organic labeling.[40] In the European Union, fish labeling as to species, method of production and origin, has been required since 2002.[41]

Concerns continue over the labeling of salmon as farmed or wild caught, as well as about the humane treatment of farmed fish. The Marine Stewardship Council has established an Eco label to distinguish between farmed and wild caught salmon,[42] while the RSPCA has established the Freedom Food label to indicate humane treatment of farmed salmon as well as other food products.[41]

Indoor fish farming

An alternative to outdoor open ocean cage aquaculture, is through the use of a recirculation aquaculture system (RAS). A RAS is a series of culture tanks and filters where water is continuously recycled and monitored to keep optimal conditions year round. To prevent the deterioration of water quality, the water is treated mechanically through the removal of particulate matter and biologically through the conversion of harmful accumulated chemicals into nontoxic ones.

Other treatments such as UV sterilization, ozonation, and oxygen injection are also used to maintain optimal water quality. Through this system, many of the environmental drawbacks of aquaculture are minimized including escaped fish, water usage, and the introduction of pollutants. The practices also increased feed-use efficiency growth by providing optimum water quality (Timmons et al., 2002; Piedrahita, 2003).

One of the drawbacks to recirculation aquaculture systems is water exchange. However, the rate of water exchange can be reduced through aquaponics, such as the incorporation of hydroponically grown plants (Corpron and Armstrong, 1983) and denitrification (Klas et al., 2006). Both methods reduce the amount of nitrate in the water, and can potentially eliminate the need for water exchanges, closing the aquaculture system from the environment. The amount of interaction between the aquaculture system and the environment can be measured through the cumulative feed burden (CFB kg/M3), which measures the amount of feed that goes into the RAS relative to the amount of water and waste discharged.

From 2011, a team from the University of Waterloo led by Tahbit Chowdhury and Gordon Graff examined vertical RAS aquaculture designs aimed at producing protein-rich fish species.[43][44] However, because of its high capital and operating costs, RAS has generally been restricted to practices such as broodstock maturation, larval rearing, fingerling production, research animal production, SPF (specific pathogen free) animal production, and caviar and ornamental fish production. As such, research and design work by Chowdhury and Graff remains difficult to implement. Although the use of RAS for other species is considered by many aquaculturalists to be currently impractical, there has been some limited successful implementation of this with high value product such as barramundi, sturgeon and live tilapia in the US[45] eels and catfish in the Netherlands, trout in Denmark[46] and salmon is planned in Scotland[47] and Canada.[48]

Slaughter methods

Tanks saturated with carbon dioxide have been used to make fish unconscious. Then their gills are cut with a knife so that the fish bleed out before they are further processed. This is no longer considered a humane method of slaughter. Methods that induce much less physiological stress are electrical or percussive stunning and this has led to the phasing out of the carbon dioxide slaughter method in Europe.[49]

Inhumane methods

According to T. Håstein of the National Veterinary Institute, "Different methods for slaughter of fish are in place and it is no doubt that many of them may be considered as appalling from an animal welfare point of view."[50] A 2004 report by the EFSA Scientific Panel on Animal Health and Welfare explained: "Many existing commercial killing methods expose fish to substantial suffering over a prolonged period of time. For some species, existing methods, whilst capable of killing fish humanely, are not doing so because operators don’t have the knowledge to evaluate them."[51] Following are some of the less humane ways of killing fish.

More humane methods

Proper stunning renders the fish unconscious immediately and for a sufficient period of time such that the fish is killed in the slaughter process (e.g. through exsanguination) without regaining consciousness.

Photo gallery

See also

Notes

  1. 1 2 World aquaculture production of fish, crustaceans, molluscs, etc., by principal species in 2013 FAO Yearbook of Fisheries Statistics 2014
  2. ↑ < http://www.ftai.com/article.htm#FFNsep14>
  3. ↑ Fishery and Aquaculture Statistics: Aquaculture Production 2008 FAO Yearbook, Rome.
  4. ↑ "Farming the Sea". Retrieved 30 January 2016.
  5. ↑ Stress and Physiology By Dr. BiIl Krise at Bozeman Technology Center, and Dr. Gary Wedemeyer at Western Fisheries Research Center. January 2002
  6. ↑ Torrissen, Ole, et al. "Atlantic Salmon (Salmo Salar): The 'Super-Chicken' Of The Sea?." Reviews In Fisheries Science 19.3 (2011): 257-278. Academic Search Premier. Web. 13 Nov. 2014.
  7. ↑ Weaver, D E (2006) Design and operations of fine media fluidized bed biofilters for meeting oligotrophic water requirements Aquacultural Engineering 34(3): 303-310.
  8. ↑ Avnimelech Y, M Kochva, et al. (1994) Development of controlled intensive aquaculture systems with a limited water exchange and adjusted carbon to nitrogen ratio. Israeli Journal of Aquaculture Bamidgeh 46(3): 119-131.
  9. 1 2 3 http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252011000400024
  10. ↑ "Offshore fish farming legislation". Retrieved 30 January 2016.
  11. ↑ "Lecture Notes on Composite Fish Culture and its Extension in India". Retrieved 30 January 2016.
  12. ↑ Pond fish farming
  13. ↑ Berggren, Alexandra (2007) Aquaculture in Sweden towards a sustainable future?" Master's Thesis, Stockholm University.
  14. ↑ McLarney, William Freshwater Aquaculture: A Handbook for Small Scale Fish Culture in North America
  15. ↑ "Aquaculture". Archived from the original on January 6, 2012. Retrieved 30 January 2016.
  16. ↑ "Fuss over Farming Fish, Alaska Science Forum". Retrieved 30 January 2016.
  17. ↑ "Current issues in fish welfare". Journal of Fish Biology 68 (2): 332–372. 2006. doi:10.1111/j.0022-1112.2006.001046.x.
  18. ↑ Sea Lice and Salmon: Elevating the dialogue on the farmed-wild salmon story Watershed Watch Salmon Society, 2004.
  19. ↑ Bravo, S (2003). "Sea lice in Chilean salmon farms". Bull. Eur. Assoc. Fish Pathol 23: 197–200.
  20. ↑ Morton, A.; Routledge, R.; Peet, C.; Ladwig, A. (2004). "Sea lice (Lepeophtheirus salmonis) infection rates on juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon in the nearshore marine environment of British Columbia, Canada". Canadian Journal of Fisheries and Aquatic Sciences 61: 147–157. doi:10.1139/f04-016.
  21. ↑ Peet, C. R. 2007. Thesis, University of Victoria.
  22. ↑ Krkošek, M.; Gottesfeld, A.; Proctor, B.; Rolston, D.; Carr-Harris, C.; Lewis, M.A. (2007). "Effects of host migration, diversity, and aquaculture on disease threats to wild fish populations". Proceedings of the Royal Society of London, Ser. B 274: 3141–3149. doi:10.1098/rspb.2007.1122. PMC 2293942. PMID 17939989.
  23. ↑ Morton, A.; Routledge, R.; Krkošek, M. (2008). "Sea louse infestation in wild juvenile salmon and Pacific herring associated with fish farms off the east-central coast of Vancouver Island, British Columbia". North American Journal of Fisheries Management 28: 523–532. doi:10.1577/m07-042.1.
  24. ↑ Krkošek, M.; Lewis, M.A.; Morton, A.; Frazer, L.N.; Volpe, J.P. (2006). "Epizootics of wild fish induced by farm fish". Proceedings of the National Academy of Sciences 103: 15506–15510. doi:10.1073/pnas.0603525103. PMC 1591297. PMID 17021017.
  25. ↑ Krkošek, Martin; et al. (2007). "Report: "Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon". Science 318 (5857): 1772–1775. doi:10.1126/science.1148744. PMID 18079401.
  26. ↑ Ford, JS; Myers, RA (2008). "DOI 10.1371/journal.pbio.0060033 "A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids". PLoS Biol 6 (2): e33. doi:10.1371/journal.pbio.0060033.
  27. ↑ University of Maine, Department of Animal, Veterinary and Aquaculture Sciences, "Sea Lice Information".
  28. ↑ Fish Farms Drive Wild Salmon Populations Toward Extinction
  29. ↑ "Northwest Fishletter". Retrieved 30 January 2016.
  30. ↑ Lymbery, P. CIWF Trust report, "In Too Deep - The Welfare of Intensively Farmed Fish" (2002)
  31. ↑ Facts About Antibiotic Resistance
  32. ↑ UNH Aquaculture website
  33. ↑ Barrionuevo, Alexei (July 26, 2009). "Chile’s Antibiotics Use on Salmon Farms Dwarfs That of a Top Rival’s". The New York Times. Retrieved 2009-08-28.
  34. ↑ Bulletin of the European Association of Fish Pathologists 22 (2): 117–125. 2002. Missing or empty |title= (help)
  35. ↑ Naylor, RL; Goldburg, RJ; Mooney, H; et al. (1998). "Nature's Subsidies to Shrimp and Salmon Farming". Science 282 (5390): 883–884. doi:10.1126/science.282.5390.883.
  36. 1 2 redOrbit. "Salmon Farming Tactics Produce Unhealthy Fish". Redorbit. Retrieved 30 January 2016.
  37. ↑ "Purdue scientists: Genetically modified fish could damage ecology". Retrieved 30 January 2016.
  38. ↑ "Alaska Passes Law Requiring Mandatory Labeling of Genetically Engineered Fish". Retrieved 29 June 2010.
  39. ↑ "Consumer Reports reveals that farm-raised salmon is often sold as "wild"". July 5, 2006. Retrieved 29 June 2010.
  40. ↑ Eilperin, Juliet; Black, Jane (November 20, 2008). "USDA Panel Approves First Rules For Labeling Farmed Fish 'Organic'". The Washington Post. Retrieved 29 June 2010.
  41. 1 2 "Environmental Labelling". Archived from the original on March 25, 2010. Retrieved 29 June 2010.
  42. ↑ "MSC eco-label helps consumers identify certified wild Alaska salmon". January 15, 2004. Retrieved 29 June 2010.
  43. ↑ Whyte, Murray (2008-07-27). "Is high rise farming in Toronto's future?". Toronto Star. Retrieved 2008-08-12.
  44. ↑ "Sky Farm Proposed for Downtown Toronto". TreeHugger. Retrieved 2009-03-14.
  45. ↑
  46. ↑ Martins, C. I. M.; Eding, E. H.; Verdegem, M. C. J.; Heinsbroek, L. T. N.; Schneider, O.; Blancheton, J. P.; d’Orbcastel, E. R.; Verreth, J. A. J. (2010). "New developments in recirculating aquaculture systems in Europe: A perspective on environmental sustainability" (PDF). Aquacultural Engineering 43 (3): 83–93. doi:10.1016/j.aquaeng.2010.09.002. Retrieved 22 January 2013.
  47. ↑ Merrit, Mike (13 January 2013) Sea-change as farm grows fish on land The Scotsman, Retrieved 22 January 2013
  48. ↑ Shore, Randy (17 November 2012) Salmon farming comes ashore in land-based aquaculture The Vancouver Sun, Retrieved 21 February 2013
  49. ↑ Victoria Braithwaite (2010) Do fish feel pain?, Oxford University Press, p. 180
  50. ↑ Håstein 2004, pp. 224.
  51. 1 2 European Food Safety Authority 2004, pp. 22.
  52. ↑ Benson, pp. 23.
  53. ↑ Yue, pp. 4.
  54. ↑ Yue, pp. 6.
  55. ↑ "Slaughter of farmed fish - fishcount.org.uk". Retrieved 30 January 2016.
  56. 1 2 Yue, pp. 7.

References

External links

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