The salmon aquaculture is farming and harvesting salmon under controlled conditions for commercial and recreational purposes. Salmon (especially salmon and rainbow trout), along with carp, are two of the most important groups of fish in cultivation. The most widely used salmonid commercially is the Atlantic salmon. In the US, Chinook salmon and rainbow trout are the most cultivated salmon for recreational and subsistence fishing through the National Fish Hatchery System. In Europe, brown trout is the most commonly preserved fish for recreational refreshment. Groups of nonsalmonid fish that are commonly cultivated include tilapia, catfish, sea fish, and freshwater fish.
In 2007, salmon aquaculture was worth US $ 10.7 billion globally. Salmonid aquaculture production grew more than tenfold over 25 years from 1982 to 2007. Leading producers of farmed salmon were Norway with 33%, Chile with 31%, and other European producers with 19%.
There is much controversy about the ecological and health effects of intensive salmon farming. Particular attention is the impact on wild salmon and other marine life. Some of these controversies are part of a major commercial competitive battle for market share and prices among Alaska's commercial salmonids fishermen and the rapidly growing salmon aquaculture industry.
Video Aquaculture of salmonids
Method
Aquaculture or salmon farming can be contrasted by catching wild salmon using commercial fishing techniques. However, the concept of "wild" salmon as used by the Alaska Seafood Marketing Institute includes fish stock increases produced in hatcheries that have historically been considered sea farms. The percentage of Alaskan salmon harvest produced from marine farms depends on salmon species and location.
The method of salmonid aquaculture comes from the conception of an 18th century experiment in Europe. At the end of the 19th century, salmon hatcheries were used in Europe and North America. From the late 1950s, hatchery based breeding programs were established in the United States, Canada, Japan, and the Soviet Union. Contemporary engineering using floating sea cages originated in Norway in the late 1960s.
Salmonides are usually cultivated in two stages and in some places may be more. First, salmon is hatched from eggs and raised on land in fresh water tanks. Increasing the accumulation of water thermal units during incubation reduces the time to hatching. When they are 12 to 18 months old, the smolt (juvenile salmon) is transferred to a floating sea cage or nets anchored in sheltered bays or fjords along the coast. This farm in marine environment is known as marine aquaculture. There they were fed pellet feed for 12 to 24 months, when it was harvested.
Norway produces 33% of the world's farmed salmon, and Chile produces 31%. The coastline of these countries has the appropriate water temperature and many areas are well protected from the storm. Chile is close to large forage fisheries that supply fish food for salmon cultivation. Scotland and Canada are also significant producers.
Modern salmon farming system is very intensive. Their ownership is often under the control of large agribusiness companies, operating mechanical assembly lines on an industrial scale. In 2003, nearly half of the world's salmon farming was produced by only five companies.
Hatcheri
Modern commercial nurseries to supply salmon smolts to aquaculture webs have turned to recirculating aquaculture systems (RAS) where water is recycled in the hatchery. This allows the hatching location to be independent of significant freshwater supply and allows economical temperature control to accelerate and slow the growth rate to match the needs of the net pen.
Conventional hatching systems operate stream-through, where springs or other water sources flow into hatching. The eggs are then hatched in a tray and the salmon smolts are produced in the race. Waste products from growing salmon and feed are usually dumped into the local river. Conventional flow-through breeding, for example the majority of Alaska's additional improvements, uses more than 100 tons (16,000 watts) to produce one kg of smolts.
An alternative method for hatching in a freshwater tank is to use a spawning channel. This is an artificial flow, usually parallel to the existing flow with concrete or rip-rap sides and gravel base. Water from adjacent streams is channeled to the top of the channel, sometimes through a header pond to precipitate sediment. Spawning success is often much better on the channel than in adjacent rivers due to flood control that in a few years can wash the natural red. Because of the lack of flooding, the spawning channel sometimes has to be cleaned to remove sediment accumulation. The same flood that destroys natural reddies also cleans it up. Spawning channels maintain natural selection from natural streams because there is no temptation, such as in hatcheries, to use prophylactic chemicals to control disease. However, exposing fish to wild parasites and pathogens using uncontrolled water supplies, combined with the high cost of spawning channels, makes this technology unsuitable for salmon farming. This type of technology is only useful for stock improvement programs.
Sea cages
Sea cages, also called sea cages or clean pens, are usually made of nets that are framed with steel or plastic. They can be square or circular, 10 to 32 m (33 to 105 ft) and a depth of 10 m (33 ft), with volumes between 1,000 and 10,000 m 3 (35,000 and 353,000 cuÃ, ft). Large sea cages can hold up to 90,000 fish.
They are usually placed side by side to form a system called seafarm or seasite, with floating docks and pathways along the net margin. Additional nets can also surround a seafarm to prevent predatory marine mammals. The density of the penis ranges from 8 to 18 kg (18 to 40 pounds)/m 3 for Atlantic salmon and 5 to 10 kilograms (11 to 22 pounds)/m 3 for Chinook salmon.
In contrast to closed systems or recirculation, open net cages from salmonid farms lower production costs, but do not provide an effective barrier to waste disposal, parasites, and diseases to the surrounding coastal waters. Salmon grown in open cages can escape to wild habitats, for example, during storms.
The waves emerging in cultivation are applying the same farming methods used for salmon to other carnivorous finfish species, such as codfish, bluefin tuna, halibut, and snapper. However, this may have the same environmental shortcomings as salmon farming.
The second emerging wave in aquaculture is the development of copper alloys as a mesh material. Copper alloys have become an important mesh material because they are antimicrobial (ie, they destroy bacteria, viruses, fungi, algae, and other microbes), so thery prevents biofouling (ie, unwanted accumulation, adhesion, and growth of microorganisms, plants, algae , tube worms, barnacles, mollusks, and other organisms). By inhibiting microbial growth, the copper alloy cultivation avoids costly clean changes required with other materials. The growing resistance of organisms to copper alloys also provides a cleaner and healthier environment for aquaculture to grow and develop.
Feed
Salmon is a carnivore and is currently being fed fish compounds containing fish meal and other feed ingredients, ranging from wheat by-products to soybean meal and flour. Being a water carnivore, salmon does not tolerate or precisely metabolize many plant-based carbohydrates and use fat as a substitute for carbohydrates as the main energy source.
With worldwide fish flour production numbers almost constant over the last 30 years and on maximum continuous yields, many of the fish meal markets have shifted from chicken and pig feed to shrimp and fish as aquaculture has grown today..
The work is continued by replacing vegetable protein and protein concentrate for fish meal in salmonid diet. In 2014, enzymatic processes can be used to lower the carbohydrate content of barley, making it a high protein food suitable for salmon. Many other substitutes for fish meal are known, and a diet containing zero fish meal is possible. For example, closed sealed fish farms in Scotland use ragworm, algae, and amino acids as feed. However, the commercial animal animal diet is determined by the least costly linear programming model that effectively competes with similar models for chicken and pig feed for the same feed ingredients, and this model shows that fish meal is more useful in aquatic diet than chicken food. , where they can make chicken taste like a fish. Unfortunately, this substitution can produce lower levels of omega-3 in agricultural products. However, when vegetable oils are used in diets that develop as a source of energy and a different finishing diet that contains high omega-3 fatty acids from fish oil, algae oil, or some vegetable oil used a few months before harvest, the problem is eliminated.
Today, more than half of world fish oil production is fed to farmed salmon.
Salmon-raised farms are also fed astaxanthin and canthaxanthin carotenoids, so their meat color matches wild salmon, which also contains the same carotenoid pigments from their diet in the wild.
On a dry-dry basis, 2-4 kg of wild catch fish is required to produce 1 kg of salmon. Wild salmon requires about 10 kg of forage to produce 1 kg of salmon, as part of a normal trophic level energy transfer. The difference between the two figures is related to the cultivated salmon feed containing other ingredients outside the fish meal and because the cultivated fish does not excite the hunting of energy.
The American company Cargill has conducted research with EWOS on alternative feeds in the RAPID feed program and COMPASS in Norway. This method studies the macronutrient profile of fish feed based on geography and season. Using RAPID feed, salmon farms reduced the time to mature salmon by about 15 months, within a fifth faster than usual.
Harvest
Modern harvesting methods are shifting towards using well-dug wines to transport live salmon to a processing plant. This allows fish to be killed, dried, and loaded before stiffness has occurred. It produces superior product quality to customers, along with more humane processing. To get the maximum quality, minimize the stress levels required in living salmon until it is completely killed electrically and percussion and gill slits for bleeding. Improvements in final processing and freshness to end customers are commercially significant and force commercial wild fisheries to improve their processing for the benefit of all seafood consumers.
The old harvesting method is by using sweeping nets, which operate a bit like a purse seine net. Net sweep is a large net with weights along the bottom edge. It stretches across the pen with the lower end extending to the bottom of the pen. The lines attached to the bottom corner are raised, herding some fish into the wallet, where they are netted. Before killing, fish are usually made unconscious in water saturated in carbon dioxide, although this practice is being phased out in some countries due to quality and ethical issues. The more sophisticated system uses a percussion stun harvest system that kills fish instantly and humanely with a blow to the head of a pneumatic piston. They then bleed by cutting gill arches and immediately immerse them in ice water. Methods of harvesting and killing are designed to minimize scale loss, and avoid fish releasing stress hormones, which negatively affect the quality of meat.
Maps Aquaculture of salmonids
Wild versus farming
Wild salmon are caught from wild habitat using commercial fishing techniques. Most of the wild salmon were caught in North American, Japanese, and Russian fisheries. The following table shows a change in the production of wild salmon and salmon grown for 25 years, as reported by FAO. Russia, Japan and Alaska all operate a major hatchery-based stock improvement program that is truly an ocean farm. The resulting fish hatching fish is defined as "wild" for FAO and marketing purposes.
Problem
Currently, much controversy concerns the ecological and health effects of intensive salmon farming. Particular attention is the impact on wild salmon and other marine life and on the income of commercial salmonid fishermen. However, 'enhanced' salmon production - which for example leads to a double-digit proportion (20-50%) of Alaska's 'annual' salmon harvest - is not hollow of controversy, and Alaska salmon harvest is highly dependent on the operations of the Alaska Regional Aquaculture Association. Furthermore, the sustainability of cultured/cultured 'wild' salmon has long been debated, both from a scientific and political/marketing perspective. Such debates and positions are vital to be 'discontinued' in the re-certification of the Alaskan salmon fisheries by the Marine Stewardship Council (MSC) by 2012. The Alaska salmon fishery then regains MSC certification status; but the highly-dependent Prince William Sound (PWS) certifying unit ("one of the most valuable fishing areas in the State") for several years is excluded from MSC certification (it remains 'under assessment' pending further analysis).
Diseases and parasites
In 1972, Gyrodactylus, a monogenean parasite, was introduced with live trout and live salmon from Sweden (Baltic stock resistant to it) to a government-operated hatchery in Norway. From hatcheries, infected eggs, shocks, and seeds are planted in many rivers in order to strengthen wild salmon stocks, but instead cause damage to some affected wild salmon populations.
In 1984, infectious salmon anemia (ISAv) was found in Norway in Atlantic salmon seedlings. Eighty percent of the fish in the plague died. ISAv, a viral disease, is now a major threat to the survival of Atlantic salmon farming. Now is the first of the diseases classified on List One of the European Commission's fish health regimen. Among other measures, this requires total eradication of all fish stocks if disease outbreaks are confirmed at any farm. ISAv seriously affects salmon farms in Chile, Norway, Scotland, and Canada, causing huge economic losses for infected farms. As the name suggests, it causes anemia of infected fish. Unlike mammals, fish red blood cells contain DNA, and can be infected with the virus. Fish develop pale gills, and can swim near the surface of the water, while breathing air. However, this disease can also develop without fish showing signs of external disease, the fish maintain a normal appetite, and then they suddenly die. The disease can progress slowly across infected farms, and in the worst cases, the mortality rate may be close to 100%. This is also a threat to the decreasing stock of wild salmon. Management strategies include developing vaccines and increasing genetic resistance to disease.
In the wild, diseases and parasites are usually at a low level, and kept in check by natural predation on weak individuals. In a crowded clean enclosure, they can become epidemics. Diseases and parasites also migrate from farms to wild salmon populations. A recent study in British Columbia linked the spread of parasite sea lice from river salmon farms to wild pink salmon in the same river. The European Commission (2002) concludes, "Reduced abundance of wild salmon is also linked to other factors but there is growing scientific evidence that builds a direct link between the number of wild fish infested with ticks and the presence of the cages in the same place. It is reported that wild salmon on the west coast of Canada is undergoing extinction by sea lice from nearby salmon farms. This prediction has been debated by other scientists and the recent harvest indicates that the prediction is false. In 2011, Scottish salmon farms introduced the use of cultivated catfish for the purpose of clearing planted salmon from ectoparasites.
Globally, salmon production is down about 9% by 2015, largely due to acute outbreaks of sea lice in Scotland and Norway. Lasers are used to reduce flea infections.
By 2017, nearly half of Scottish salmon farms are full of salmon lice. The problem is growing all over the world, with ticks much more resilient than the industry thinks. Don Staniford, a former scientist turned activist and investigator, said the disease spread in fish farms, uncontrolled waste, and the use of chemicals grew rapidly. According to him, the fish farm industry is now close to destroying itself.
Pollution and contaminants
Salmonid farms are usually located in marine ecosystems with good water quality, high water exchange rates, current speeds are fast enough to prevent contamination from below but are slow enough to prevent pen damage, protection from major storms, reasonable water depths and distances it makes sense from key infrastructure such as ports, processing plants, and logistics facilities such as airports. Logistics considerations are significant, and feed and maintenance labor must be transported to facilities and products returned. Decision-making is complicated by the complicated and politically driven permitting problems in many countries that prevent optimal location for agriculture.
In a site without sufficient current, heavy metals can accumulate in benthos (seafloor) near salmon farms, especially copper and zinc.
Contaminants are commonly found in wild and cultured salmon meats.
A 2004 study, reported in Science, analyzed the farmed and wild salmon for organochlorine contaminants. They found higher contaminants in cultivated salmon. In farmed salmon, European (mainly Scottish) salmon has the highest level, and the lowest Chilean salmon. FDA and Canada Health have established tolerance/limits for PCBs in commercial fish 2000 ppb Further research confirmed this, and found levels of dioxin, chlorinated pesticides, PCBs and other contaminants up to ten times greater in salmon cultivated than wild Pacific salmon. On a positive note, further studies using the same fish samples used in previous studies, showed that the cultured salmon contained beneficial levels of fatty acids that were two to three times higher than wild salmon. A follow-on benefit-risk analysis on salmon consumption balances cancer risk with n-3 fatty acid benefits from salmon consumption. For this reason, the current method for this type of analysis considers the lipid content of the sample in question. Special PCBs are lipophilic, so they are found in higher concentrations in fatty fish in general, so higher levels of PCB in cultured fish are associated with higher content of the beneficial lipids n-3 and n-6 ​​they contain. They found that the recommended level of fatty acid consumption (n-3) could be achieved by eating farmed salmon with an acceptable carcinogenic risk, but the recommended level of EPA DHA intake could not be achieved only from raised (or wild) salmon without carcinogenic risk not acceptable. The conclusion of this paper from 2005 is that
"... consumers should not eat fish cultivated from Scotland, Norway and eastern Canada more than three times a year; fish cultivated from Maine, western Canada and Washington state no more than three to six times a year; and fish cultivated from Chile no more than about six times a year Wild chum salmon can be taken safely as often as once a week, pink salmon, Sockeye and Coho about twice a month and Chinook only once a month. "
In 2005, Russia banned the import of cold fish from Norway, after sampling of Norwegian aquaculture fish showed high levels of heavy metals. According to Russian Agriculture Minister Aleksey Gordeyev, the lead level in the fish is 10 to 18 times higher than Russian security standards and cadmium levels are almost four times higher.
In 2006, eight Norwegian salmon producers were caught using unauthorized and unlabeled nitrites in smoked salmon and cured. Norway applies EU regulations on food additives, which it says nitrites are allowed as food additives for certain types of meat, but not fish. Fresh salmon is not affected.
A research paper from 2008 entitled "Balancing the risks and benefits of fish for sensitive populations" contradicts the above recommendations given the fact that the levels all in the study averaged 1% of those designated as the maximum by the FDA, CIA, and EFSA, and each risk caused by these contaminants far outweighs the proven benefits of eating planted or wild salmon. Due to this fact: Health Canada currently believes that there is no need for any specific advice on fish consumption, vis-ÃÆ'-vis PCB exposure.
Currently, dietary guidelines Canada recommends eating at least two portions of Fish Food Guide every week and choosing fish such as char, herring, mackerel, salmon, sardines, and trout.
The US in their dietary guidelines for 2010 recommends eating 8 ounces per week of various seafood and 12 ounces for nursing mothers, with no set upper limit and no restrictions on eating farmed or wild salmon.
"The updated monitoring of dioxin levels and PCBs in food and feed" to the European Food Safety Authority in July 2012 suggests that salmon and farmed trout contain fewer dioxins and PCBs than wildly caught salmon and trout. "
Kurt Oddekalv, leader of the Green Warriors of Norway, argues that the scale of fish farms in Norway is unsustainable. Large amounts of uneaten feed and fish debris contaminate the seafloor, while chemicals designed to fight sea lice find their way into the food chain. He said: "If people know this, they will not eat salmon", describes the fish cultivated as "the most poisonous food in the world". Don Staniford agrees, saying that a 10-fold increase in the use of some chemicals is evident within the 2016-2017 timeframe. The use of toxic drugs emamektin increases rapidly. The level of chemicals used to kill sea lice has violated the environmental safety limits more than 100 times in the last 10 years.
Impact on wild salmon
Farmed salmon can, and often, escape from sea cages. If the cultivated salmonids are not genuine, they can compete with native wild species for food and habitat. If the cultivated salmonid is genuine, it can crosslink with wild native salmon. Such cross-breeding can reduce genetic diversity, disease resistance, and adaptability. In 2004, about 500,000 salmon and trout escaped from Norwegian offshore fishing catchers. Around Scotland, 600,000 salmon were released during the storm. Commercial fishermen targeting wild salmon are not uncommon for catching runaway salmon. At one stage, in the Faroe Islands, 20 to 40 percent of all fish caught escaped from farm salmon. By 2017, about 263,000 cultured foreign salmon successfully escaped from nets in Washington waters at the 2017 Atlantic Cypress Island salmon shootings.
Sea lice, especially salmonic lepeophtheirus and various species of Caligus, including C. clemensi and C. rogercresseyi, may cause deadly infestations of salmon grown on farms and wild. Marine lice are naturally occurring and abundant ectoparasites that feed on mucus, blood, and skin, and migrate and adhere to the salmon skin during the larval stage of pluptoni nauplii and copepodid, which can persist for several days. A large number of open salmon farms with open populations can create enormous concentrations of sea lice; when exposed at the mouth of a river containing a large number of open farms, many young wild salmon are infected, and do not survive as a result. Adult salmon can survive if there is no critical number of sea lice, but small, thin-skinned migrants migrating to the sea are particularly vulnerable. In 2007, mathematical studies of available data from the Pacific coast of Canada showed mortality of flea-induced salmon salmon in some areas by more than 80%. Later that year, in reaction to the above-mentioned 2007 mathematical study, Canadian federal fisheries scientists Kenneth Brooks and Simon Jones published a critique entitled "Perspectives on Red and Marine Lice Salmon: Scientific Evidence Failed to Support the Extinction Hypothesis" Time since this study has shown a general increase of the abundance of Pink Salmon in Broughton Archipelago. Other comments in scientific literature by Canadian Government Fisheries scientist Brian Riddell and Richard Beamish et al. came to the conclusion that there was no correlation between the number of livestock salmon infestation and the return of pink salmon to Broughton Archipelago. And in relation to the Krkosek 2007 extinction theory: "the data used selectively and conclusions do not match recent observations of returned salmon".
A 2008 meta-analysis of available data suggests that salmonid farming reduces the viability of salmonid-related populations. This relationship has been proven to apply to Atlantic, steelhead, pink, chum, and coho salmon. The decrease in survival or abundance often exceeds 50%. However, this study is all correlation and correlation analysis is not the same as the cause, especially when a similar salmon drop occurs in Oregon and California, which have no salmon or marine cultivation. Independent of the predicted failure of salmon running in Canada demonstrated by this study, wild salmon that was carried out in 2010 was a record harvest.
A 2010 study that made the first use of sea lice counts and fish production data from all salmon farms in Broughton Archipelago found no correlation between the number of flea lice and wild salmon survival. The authors conclude that stock collapse in 2001 was not caused by sea lice populations. The study found that the population of marine infestation on livestock during juvenile juvenile salmon migration was larger in 2000 than in 2001, but a record of salmon escape in 2001 caused a 2002 maritime louse to collapse in the absence of a negative correlation. The authors also note that initial research did not investigate the causes of bacteria and viruses for the occurrence despite reports of bleeding in the fin base, a symptom often associated with infection, but not with exposure to sea lice under laboratory conditions.
The wild salmon fish was anadromous. They spawn into the interior in fresh water and when young migrate to the oceans where they grow up. Most of the salmon go back to the river where they were born, though some get lost into other rivers. There is concern about the role of genetic diversity in salmon. Population resilience depends on some fish that can withstand environmental shocks, such as extreme temperatures. The effect of hatchery production on genetic diversity of salmon is also unclear.
Genetic modification
Salmon has been genetically modified in the laboratory so they can grow faster. A company, Aqua Bounty Farms, has developed a modified Atlantic salmon that grows almost twice as fast (producing adult fish at 16-18 months and not 30), and is more resistant to disease, and cold tolerance. It also requires 10% less food. This is achieved by using a sequence of chinook salmon genes that affect growth hormone, and the promoter sequence of sea pigment affects antifreeze production. Usually, salmon produces growth hormone only in the presence of light. Modified salmon does not alter the production of growth hormone. The company first submitted salmon for FDA approval in 1996. By 2015, the FDA has approved AquAdvantage Salmon for commercial production. Concerns with GMO salmon are what might happen if they escape into the wild. One study, in a laboratory setting, found that modified salmon mixed with their wild cohorts was aggressive in competing, but ultimately failed.
Impact on wild predator species
Sea cages can attract a variety of wild predators that can sometimes get entangled in related nets, causing injury or death. In Tasmania, the Australian salmon-farming enclosure ensnares a white sea eagle. This has prompted a company, Huon Aquaculture, to sponsor a bird rehab center and try a stronger net.
Impact on forage fish
The use of fish feed for fish meal production has been almost constant for the last 30 years and at maximum sustainable yield, while the market for fish meal has shifted from chicken, pork and pet food to aquaculture diet. The fact that this market shift in constant production is an economic decision that has no impact on the rate of harvest of forage fish for fish meal implies that the development of salmon farming has no impact on the rate of forage fish.
Fish do not actually produce omega-3 fatty acids, but they accumulate them from consuming the microalgae that produce these fatty acids, as well as forage fish such as herring and sardines, or as with fatty predator fish, like salmon, by eating prey fish that have collected omega-3 fatty acids from microalgae. To meet this requirement, more than 50% of world fish oil production is fed to cultivated salmon.
In addition, salmon requires intake of protein nutrients, which are often given to them in the form of fish meal as an alternative protein at the lowest cost. As a result, the cultivated salmon consume more fish than they produce as the final product, though it is much preferable as food.
Salmon & amp; ASC Salmon Standard
In 2004, the World Wide Fund for Nature (WWF) -USA initiated the Salmon Aquaculture Dialogue, one of several Aquaculture Dialogues. The purpose of this dialogue is to produce environmental and social standards for cultivated salmon and other species (12 species today, by 2018). Since 2012, the standards outlined by the multi-stakeholder Dialogue are forwarded to the Aquaculture Stewardship Council (ASC) created in 2010 to manage and further develop them. The first standard is the ASC Salmon Standard (June 2012, and revised in 2017 after comprehensive public consultation). WWF initially identified what they called the "seven major environmental and social impacts", characterized as:
Hatch and release
Another form of salmon production, which is safer but less controlled, is to increase salmon in hatcheries until they are old enough to become self-sufficient. They are then released into the river, often in an attempt to increase salmon populations. This practice is very common in countries such as Sweden before Norway develops salmon farming, but it is rarely done by private companies, because anyone can catch salmon when they return to laying eggs, limiting the chances of companies getting financial returns from their investments. Therefore, this method has mainly been used by various public authorities and nonprofit groups, such as the Association of Raising Cooking Fisheries, as a way of artificially raising salmon populations in situations where they have refused due to overharvest, dam construction, and habitat of destruction or disturbance. Unfortunately, negative consequences for such population manipulation may occur, including genetic "dilution" of wild stocks, and many jurisdictions are now beginning to prevent additional fish cultivation in favor of crop control and habitat restoration and protection. Variants of fish stocking methods, called marine farms, are under development in Alaska. There, young salmon is released into the ocean far from the wild salmon river. When it comes time to lay eggs, they return to where they are released where fishermen can catch them.
Species
Atlantic salmon
In their birth flows, Atlantic salmon is considered a valuable recreational fish, pursued by an avid flyflies during its annual journey. At one time, the species supported important commercial fisheries and additional food fisheries. However, wild Atlantic salmon fisheries are commercially dead; after extensive habitat destruction and overfishing, wild fish make up only 0.5% of the Atlantic salmon available in the world fish market. The remaining cultivated, mainly from cultivation in Chile, Canada, Norway, Russia, England, and Tasmania.
Atlantic salmon, by far, is the species most often chosen for farming. It is easy to handle, grows well in a sea cage, commands high market value, and adapts well to be processed away from its natural habitat.
Adult and female fish are sedated. Eggs and sperm are "stripped naked", after the fish is cleaned and the cloth is dried. Sperm and eggs are mixed, washed, and placed into fresh water. Adults recover in flowing, clean, and aerated water. Some researchers have studied cryopreservation of eggs.
Fry is generally maintained in large freshwater tanks for 12 to 20 months. Once the fish reach the phase of shock, they are taken to the sea, where they are held for two years. During this time, fish grow and mature in large enclosures off the coast of Canada, USA, or parts of Europe. Generally, the cage is made of two nets; the deep net, which encloses the cage, holds the salmon while the outer net, which is held by the buoy, keeps the predator out.
Many Atlantic salmon run away from cages in the sea. Salmon that multiplies further tends to reduce the genetic diversity of species leading to lower survival rates, and lower catch rates. On the West Coast of North America, non-native salmon can be an invasive threat, especially in Alaska and parts of Canada. This can cause them to compete with the original salmon to get the resources. Extensive efforts are underway to prevent the escape and potential spread of Atlantic salmon in the Pacific and elsewhere. The risk of Atlantic Salmon being a legitimate invasive threat on the Pacific Coast of North America is questionable given the Canadian and American governments deliberately introducing this species by millions for a 100-year period beginning in the 1900s. Despite a deliberate effort to build this species on the Pacific coast; no population has been reported.
In 2007, 1,433,708 tons of Atlantic salmon were harvested worldwide with a value of $ 7.58 billion. Then years later, by 2017, more than 2 million tons of farmed Atlantic salmon are harvested.
Steelhead
In 1989, the steelhead was reclassified to the Pacific trout as Oncorhynchus mykiss of binominal binary Salmo gairdneri (Columbia River redband trout) and S. irideus (fish trout rainbow coast). Steelhead is an anadromous form of rainbow trout that migrates between lakes and rivers and seas, and is also known as steelhead salmon or sea trout.
Steelhead grew up in many countries around the world. Since the 1950s, production has grown exponentially, particularly in Europe and recently in Chile. Worldwide, in 2007, 604,695 tonnes of cultivated steel were harvested, valued at $ 2.59 billion. The biggest producer is Chile. In Chile and Norway, the production of steel cages in the oceans has expanded to supply export markets. Inland rainbow trout production to supply the domestic market has increased strongly in countries such as Italy, France, Germany, Denmark, and Spain. Other important producing countries include the United States, Iran, Germany, and Britain. Rainbow trout, including teenage steelheads in fresh water, routinely feed on larvae, pupae, and insect-shaped insects (usually caddisflies, stonefly, dragonflies, and water dipterana). They also eat fish eggs and adult insects terrestrial forms (usually ants, beetles, grasshoppers, and crickets) that fall into the water. Other species include small fish up to one-third of its length, crayfish, shrimp, and other crustaceans. As the rainbow trout grew, the proportion of fish consumed increased in most populations. Some forms of lakes may be planktonic feeders. In rivers and rivers inhabited by other salmon species, rainbow trout feed on varied fish eggs, including salmon, chocolate and cruel trout, mountain banding fish, and other rainbow trout eggs. Rainbows also consume rotting meat from other fish carcasses. Steelheads mature in the ocean mainly feed on fish, squid, and other amphipods. Steelhead cultured diet fed are formulated to resemble their natural diets that include fish meal, fish oil, vitamins and minerals, and carotenoid asthaxanthin for pigmentation.
Steelhead is particularly vulnerable to red mouth disease. Much research has been done on redmouth disease, because the implications for the steelhead farmers are significant. It does not affect humans.
Coho salmon
Coho salmon is a state animal of Chiba, Japan.
Coho salmon is ripe after only one year at sea, so two separate spawners are required, alternating each year. Broodfish is selected from salmon in the sea and "transferred to a freshwater tank for ripening and spawning".
Around the world, in 2007, 115,376 tons of Coho planted salmon were harvested for $ 456 million. Chile, with about 90 percent of world production, is a major producer with Japan and Canada producing the rest.
Chinook salmon
Salmon Chinook is an Oregon state fish, and is known as the "king of salmon" because of its large size and its flavorful flesh. Those from the Copper River in Alaska are well known for their color, rich taste, strong texture, and high omega-3 oil content. Alaska has a long-standing ban on frozen fish cultivation enacted in 1989. The Alaska Stat. Ã,§ 16.40.210
Worldwide, in 2007, 11,542 tons (1,817,600 st) of cultured Chinook salmon were harvested for $ 83 million. New Zealand is the largest producer of cultivated king salmon, accounting for more than half of world production (7,400 tons in 2005). Most marine farmed salmon (mariculture) use a method sometimes called a cage farm, which takes place in a large floating net cage, about 25 m across and 15 m deep, tethered to the deep seabed, rapidly-flowing coastal waters. Smolt (fresh fish) from freshwater hatchery was moved to a cage containing several thousand salmon, and remained there for the rest of their lives. They were fed high fishmeal pellets of protein and oil.
Salmon Chinook is also grown in net cages placed in rivers or fresh waterways, using a technique similar to that used for salmon cultivated at sea. A unique form of freshwater salmon farming takes place in several hydroelectric channels in New Zealand. A site in Tekapo, which is flooded by the fast cool water of the Southern Alps, is the world's highest salmon farm, 677 m (2,221 ft) above sea level.
Source of the article : Wikipedia
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