A tuna is a saltwater fish belonging to the Thunnini , sub-grouping of mackerel families (Scombridae). Thunnini consists of fifteen species in five genera, of varying sizes, ranging from bullet tuna (maximum length: 50 cm (1.6 feet), weight: 1.8 kg (4 pounds)) to Atlantic bluefin tuna (long maximum: 4.6 m (15 ft), weight: 684 kg (1,508 lb)). Bluefin averages 2 m (6.6 ft), and is believed to live up to 50 years.
Tuna, Opah, shark mackerel is the only species of fish that can maintain a higher body temperature than the surrounding water. Active and agile predators, tuna has a slender lean body, and is one of the fastest swimming fish - yellow fin tuna, for example, capable of speeds up to 75 km/h (47 mph). Found in warm seas, these fish are commercially lured, and popular as hunted fish. As a result of overfishing, stocks of some tuna species, such as southern bluefin tuna, are almost extinct.
Video Tuna
Etimologi
The term tuna is basically derived from Thunnus , the Central Latin form of Ancient Greek: ?????? , translit.Ã, (thÃÆ'½nnos) , lit.Ã, 'tunny-fish'Ã, - which in turn comes from ???? ( thÃÆ'½n?), "rush, dart along".
However, the direct source for the word tuna in English is Spanish & lt; Spanish atÃÆ'ºn & lt; Arabic Andalusia at-t? N , assimilated from al-t? N ????? [Modern Arabic ????] Ã,: 'tuna' & lt; Greco-Latin thunnus mentioned above.
Maps Tuna
Taxonomy
The Thunnini Tribe is a monophyletic clone of fifteen species in five genus:
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- Scombridae family
- Thunnini tribe: buds
- genus Allothunnus: lean shoots
- genus Auxis: frigate shoots
- genus Euthynnus: small buds
- genus Katsuwonus: skipjack buds
- genus Thunnus: albacores, true seed
- subgenus Thunnus (Thunnus) : bluefin groups
- subgenus Thunnus (Neothunnus) : yellowfin group
- Thunnini tribe: buds
- Scombridae family
Cladogram is a tool to visualize and compare the evolutionary relationship between taxa, and read left-to-right as if on a time line. The following cladogram illustrates the relationship between tuna and other tribes of the Scombridae family. For example, the cladogram illustrates that the skipjack chakra is more closely related to the actual buds than the lean buds (the most primitive buds), and that the closest relatives of the buds are the bonitos of the Sardini tribe.
Original tuna species
The "original" bud is the genus of Thunnus . To date, it is estimated that there are seven species of Thunnus , and Atlantic bluefin tuna and Pacific bluefin tuna are subspecies of one species. In 1999, Collette determined that based on molecular and morphological considerations, they were actually different species.
Genus Thunnus is further classified into two subgenera: Thunnus (Thunnus) (blue fins group), and Thunnus (Neothunnus) (yellow group).
Other tuna species
The Thunnini tribe also includes seven additional tuna species in four genera. They:
Biology
Description
Tuna is a sleek and slim fish, adjusted for its speed. It has two adjacent dorsal fins on its back; The first is "depressible" - it can be laid, flush, in a groove that extends along its back. Seven to ten yellow fins run from the dorsal fin to the crescent-shaped tail - curved like a crescent moon - and tapering to the pointed ends. The base of the tail, which is attached to the tail, is quite thin, with three stable horizontal keels on each side. The tuna backs are generally dark metallic blue, while the sides of the stomach, or the lower side, are silvery or whitish, for camouflage.
Physiology
Thunnus is widely but rarely spread throughout the world's oceans, generally in tropical and subtropical waters at latitudes ranging from about 45 Â ° north and south of the equator. All tuna are able to maintain the temperature of certain parts of their body above sea water temperature. For example, the bluefin can maintain the core body temperature of 25-33 Â ° C (77-91 Â ° F), in water as cold as 6 Â ° C (43 Â ° F). However, unlike "typical" endothermic creatures such as mammals and birds, tuna does not maintain temperatures in a relatively narrow range.
Shoots reach endothermy by saving the heat generated through normal metabolism. In all tuna, the heart operates at ambient temperature, because it receives cooled blood, and direct coronary circulation of the gills. The "rete mirabile" ("extraordinary clean"), arterial blood vessels and arteries in the body, allows almost all metabolic heat from the venous blood to be "reclaimed" and transferred to the arteries. blood flow through a reverse flow exchange system, thereby reducing the effects of surface cooling. This allows the tuna to increase the temperature of the highly-aerobic tissue of skeletal muscle, eyes and brain, which supports faster swimming speeds and reduced energy expenditure, and which allows them to survive in colder waters in a wider range of marine environments than fish the other.
Also unlike most fish, which have white meat, tuna muscle tissue ranges from pink to dark red. The red myotomal muscles are derived from myoglobin, the oxygen-binding molecule, which tuna expresses in much higher quantities than most other fish. Oxygen-rich blood further enables the delivery of energy to their muscles.
For strong swimming animals such as dolphins and tuna, cavitation may be disadvantageous, as it limits their maximum swimming speed. Even if they have the power to swim faster, dolphins may have to limit their speed, because the collapse of cavitation bubbles in their tail is too painful. Cavitation also slows the tuna, but for different reasons. Unlike the dolphins, these fish do not feel the bubbles, because they have bone fin without the nerve endings. However, they can not swim faster because the cavitation bubbles create a steam film around their fins that limit their speed. Lesions have been found in tuna consistent with cavitation damage.
Fishing industry
Commercial fishing
Tuna is an important commercial fish. The International Seafood Sustainability Foundation (ISSF) compiles a detailed scientific report on the state of global tuna stocks in 2009, which includes routine updates. According to ISSF, the most important species for commercial and recreational tuna fisheries are yellowfin ( Thunnus albacares ), bigeye ( T. Obesus ), blue fins ( T. thynnus , T. orientalis , and T. macoyii ), albacore ( T. alalunga ), and skipjack ( Katsuwonus pelamis ).
Based on the catch from 2007, the report states:
Between 1940 and the mid-1960s, the annual world capture of five major market species of tuna rose from about 300 thousand tons to about 1 million tons, mostly taken by hooks and lines. With the development of trawl nets, which are now the main equipment, the catch has increased to over 4 million tonnes per year over the past few years. Of this catch, about 68 percent comes from the Pacific Ocean, 22 percent of the Indian Ocean, and the remaining 10 percent of the Atlantic Ocean and the Mediterranean Sea. Skipjack produces about 60 per cent of the catch, followed by yellowfin (24 per cent), bigeye (10 per cent), albacore (5 per cent), and the remaining blue fin. The wallets take about 62 percent of world production, longline about 14 percent, poles and lines about 11 percent, and various other remaining gears.
The Australian government alleged in 2006 that Japan had illegally overfilled southern bluefin by taking 12,000 to 20,000 tonnes per year, not an agreed 6,000 tons; the value of overfishing would reach US $ 2 billion. Such excessive arrests have greatly damaged the supply of bluefin. According to WWF, "The appetite of large tuna will take the most sought-after stock in the commercial extinction ravine unless the fisheries agree to a more rigid quota". The Japan Fisheries Research Agency states that Australian and New Zealand tuna fishing companies are less reporting on the number of southern bluefin tuna catches and ignoring the total number of internationally-caught catches.
In recent years, the opening of fish auction at the Tsukiji fish market in Tokyo has seen record prices for bluefin tuna, reflecting market demand. In each of 2010, 2011, 2012 and 2013, new record prices have been set for one fish - the current record is 155.4 million Japanese yen (1.76 million US dollars) for 221 million kg (487 lb), or one unit the price is JP Â ¥ 703,167/kg (US $ 3,603/lb). The opening auction price for 2014 dropped to less than 5% from the previous year's price, which has attracted complaints to climb the "way out of line". Summary of note setting auction is shown in the following table (highlighted value shows new world record):
In November 2011, a different note was set when a fisherman in Massachusetts caught an 881 pound tuna. It was caught unintentionally using a net. Because of the laws and restrictions on tuna fishing in the United States, federal authorities confiscate fish for not being caught with sticks and reels. Due to the worsening tuna conditions caused by trawl nets, the fish are sold for just under $ 5,000.
Fishing method
In addition to edible purposes, many species of tuna are often caught as a game, often for recreation or for contests where money is given by weight. Larger specimens are famous for making temporary fights addicted, and have been known to injure people who try to catch them, as well as damage their equipment.
- The phoenician technique for catching and catching Atlantic bluefin tuna called Almadraba , is still used today in Portugal, Spain, Morocco & amp; Italy that uses a maze of nets. In Sicily, the same method is called Tonnara .
- Fish cultivation (enclosure system)
- Tuna ranching
- Longline fishing
- Purse seine
- Pole and line
- Harpoon gun
- Fishing great game
- Fish collection tool
Association with whaling hunt
In 2005, Nauru, defended the vote from Australian critics at the International Fishing Commission meeting that year, argued that some species of whales have the potential to destroy Nauru's tuna stock, and that Nauru's food and economic security is heavily dependent on fishing. However, Nauru does not allow whaling in its own waters and does not allow other fishing vessels to take or intentionally interact with marine mammals in the Exclusive Economic Zone. In 2010 and 2011 Nauru supported Australia's proposal for a western Pacific ban on tuna purse-seining around marine mammals - a measure agreed by the Western and Central Pacific Fisheries Commission at its eighth meeting in March 2012.
Association with dolphins
Dolphins swim beside several species of tuna. This includes yellowfin tuna in the eastern Pacific Ocean, but not albacore. Tuna schools are believed to associate themselves with dolphins for protection against sharks, which are tuna predators.
Commercial fishing vessels are used to exploit this relationship by searching for dolphins. The vessel will circle the pods with a net to catch the tuna underneath, but the web tends to trap the dolphins, injure or kill them. Public condemnations and new government regulations, now monitored by NOAA have led to more "dolphin-friendly" methods, now generally involving lines rather than nets. However, there is no universal independent inspection program or verification of "dolphin safety", so this protection is not absolute. According to the Consumers Union, the resulting lack of accountability means that tuna claims that "dolphins are safe" should be given little trust.
Fisheries practices have turned into friendly dolphins, which have led to a larger bycatch including sharks, turtles and other marine fish. Fishermen no longer follow the dolphins, but concentrate their fisheries around floating objects such as fish aggregation devices, also known as Rumpon, which attract large populations of other organisms. Actions taken so far to meet public demand for protecting dolphins can potentially damage other species as well.
Aquaculture
The increasing number of high grade tuna is maintained in clean cages and bait fish baits. In Australia, former fishermen keep southern bluefin tuna, Thunnus maccoyii , and other blue species. Agriculture of its close relatives, Atlantic bluefin tuna, Thunnus thynnus, began in the Mediterranean, North America and Japan. Hawaiian ? i approved the permit for the first offshore farm in the US from bigeye tuna in the waters 1,300 feet (400 m) in 2009.
Japan is the largest tuna consumer country and also a leader in tuna agriculture research. Japan successfully first planted and maintained bluefin tuna in 1979. In 2002, successfully completed the reproductive cycle and in 2007, completed the third generation. Farm breeds are known as Kindai tuna. Kindai is a contraction of Kinki University in Japan (Kinki daigaku). In 2009, Clean Seas, an Australian company that has received help from Kinki University successfully breed Southern Bluefin Tuna in captivity and was awarded second place in World Best Discovery 2009 by Time magazine.
As food
Fresh or frozen tuna meat is widely regarded as a delicacy in most of the areas where it is shipped, being prepared in various ways to achieve a specific taste or texture. When presented as a steak, the meat of most species is known for its thickness and hard texture. Some species (such as bluefin) are also known for the large amounts of blood they remove when destroyed.
Canned
When tuna are tilled and packaged for sale, this product is sometimes called tuna .
Canned tuna was first produced in Australia in 1903, quickly becoming popular. Tuna can be canned in edible oil, in brine, in water, and in various sauces. Tuna can be processed into "chunked" or "flattened". When a product can is often referred to as a "tuna fish", a calque (translation of loan) from German Thunfisch . In the United States, 52% canned tuna is used for sandwiches; 22% for salad; and 15% for casseroles and packets of dried and pre-packaged foods such as the General Mills Tuna Helper line.
In the United States, only Albacore can legally be sold in tins as "white meat tuna"; in other countries, yellowfin is also acceptable. While in the early 1980s Australian canned tuna was probably the Southern Bluefin, in 2003 usually a yellow fin, skipjack, or tongol (labeled "northern bluefin").
Because tuna are often caught away from where they are processed, poor temporary conservation can cause decay. Tuna are usually destroyed by hand, and then pre-cooked for a prescribed time of 45 minutes to three hours. The fish are then cleaned and filled, canned, and sealed, with dark lateral blood flesh often separately canned for pet food. The sealed cans are then heated under pressure (called retort cooking) for 2 to 4 hours. This process kills any bacteria, but retains the histamine that the bacteria might produce. International standards establish a maximum histamine level at 200 milligrams per kilogram. An Australian study of 53 unflavored canned tuna varieties found none that surpassed safe histamine levels, although some had an "off" taste.
Australian standards once required tuna cans contain at least 51% tuna, but this rule was dropped in 2003. The remaining weight is usually oil or water. In the US, the Food and Drug Administration (FDA) organizes canned tuna (see section c ).
Nutrition and health
Tuna can be a good source of omega-3 fatty acids. It can contain 300 milligrams (0.011 oz) per serving. However, the level of omega-3 oil found in canned tuna is highly variable, as some common manufacturing methods destroy much of the omega-3 oils in fish. Tuna is also a good source of protein.
Mercury level
The content of mercury in tuna can vary greatly. For example, testing by Rutgers University reportedly found that a can of StarKist has 10 times more mercury than other cans with identifiable tuna. This has prompted a Rutgers University scientist whose staffs conducted mercury analysis to say, "That is one reason pregnant women should be really careful... If you happen to get some or three cans in the high range in the critical period. , it would not be good. "Among those who call for an improved warning about mercury in tuna is the American Medical Association, which adopts a policy that doctors should help make their patients more aware of their potential risks.
A study published in 2008 found that the distribution of mercury in tuna meat was inversely related to lipid content, suggesting that higher lipid concentrations in edible feeding tuna tissue may, other factors remain the same, have a dilution effect on mercury content.. These findings suggest that choosing to consume a type of tuna that has a relatively higher natural fat content may help reduce the amount of mercury intake, compared with eating low-fat tuna.
Due to its high position in the food chain and the subsequent accumulation of heavy metals from their diet, the level of mercury can be high in larger species such as bluefin and bigeye.
In 2009 the California court of appeals upheld the verdict that canned tuna did not require warning labels because the methylmercury happened naturally.
In March 2004, the FDA issued guidelines recommending that pregnant women, lactating mothers and children limit their intake of tuna and other predatory fish. The Environmental Protection Agency provides guidance on how many canned tuna are safe to eat. Roughly, the guidelines recommend one 6-ounce can (170 g) light tuna per week for individuals weighing less than 110 pounds (50 kg), and two cans per week for heavier ones.
In 2007 it was reported that some canned light tuna such as yellowfin tuna was significantly higher in mercury than skipjack tuna, and caused Consumer Union and other activist groups to advise pregnant women not to consume canned tuna.
Eastern little Tuna ( Euthynnus affinis ) have been available for decades as low-cost mercury cans, which are less expensive. However, of the five major species of tuna imported by the United States, this is the most commercially attractive, mainly because of its dark color and a more distinctive 'fishy' taste. Its use has traditionally been limited to institutional trading (non-retail).
A January 2008 investigation conducted by The New York Times found a potentially dangerous mercury level in certain types of tuna sushi, reporting "very high levels that the Food and Drug Administration can take legal action to remove fish from the market. "
A book by Jane Hightower, Mercury Diagnosis: Money, Politics and Poison, published in 2008, discusses human exposure to mercury through eating large predatory fish such as large tuna.
Management and preservation
The main tuna fisheries management bodies are the Western and Central Pacific Fisheries Commission, the Inter-American Tropical Tuna Commission, the Indian Ocean Tuna Commission, the International Commission for the Conservation of Atlantic Branch, and the Commission for the Conservation of Southern Bluefin Tuna. The five gathered for the first time in Kobe, Japan in January 2007. Environmental organizations made risk filings against fisheries and species. The meeting concludes with an action plan composed by about 60 countries or regions. Concrete measures include issuing certificates of origin to prevent illegal fishing and greater transparency in setting up regional capture quotas. Delegates are scheduled to meet at another joint meeting in January or February 2009 in Europe.
In 2010, Greenpeace International added albacore tuna, bigeye, Pacific bluefin tuna, Atlantic bluefin tuna, southern bluefin tuna, and yellowfin tuna to its red list of seafood, which is "commonly sold in supermarkets around the world, and which very high risk sourced from unsustainable fisheries. "
Bluefin tuna has been widely accepted as over-captured fish, with some stocks at risk of collapse. According to the International Seafood Sustainability Foundation (Global partnership, non-profit between tuna industry, scientist, and World Wide Fund for Nature), Indian Ocean yellow fin tuna, large Pacific eastern tuna (east and west), and Atlantic Atlantic Atlantic tuna are all overfished. In April 2009, no skipjack stock (which accounts for about 60% of all captured tuna worldwide) is considered overfishing. However, the BBC South Pacific documentary, first shown in May 2009, states that, if fishing in the Pacific continues at the current rate, the population of all tuna species may collapse within five years. It highlights the enormous Japanese and European tuna fishing vessels, shipped to South Pacific international waters after overfishing their own fish to the point of destruction.
The 2010 tuna fishery assessment report, released in January 2012 by the Pacific Community Secretariat, supports this finding, recommending that all tuna fishing should be reduced or limited to current levels and that skipjack skipjack restrictions should be considered.
Research shows that rising ocean temperatures take a toll on tuna in the Indian Ocean, where rapid warming of the ocean has resulted in reduction of marine phytoplankton. The rate of arrest of the bigeye tuna has also declined unexpectedly over the past half century, largely due to increased industrial fisheries, with ocean warming adding further pressure on fish species.
See also
- The environmental impact of fishing
- Got Mercury?
- Christmas homing
References
Further reference
- Clover, Charles. 2004. End of the Line: How Overfishing Changes the World and What We Eat . Ebury Press, London. ISBN: 0-09-189780-7
- FAO: Species Catalog Vol. 2 Scombrids World. FAO Fisheries Synopsis No. 125, Volume 2. FIR/S125 Vol. 2.ISBNÃ, 92-5-101381-0
- FAO: Review of world marine fishery resource conditions: Tuna and fish-like species - Global, 2005 Rome.
- Majkowski, Jacek (1995) "Tuna and tuna-like species" In: Overview of world marine fisheries resources , technical paper FAO Fisheries 457, FAO, Rome. ISBN: 978-92-5-107023-9.
- Majkowski J, Arrizabalaga H, Carocci F and Murua H (2011) "Species of tuna and tuna" At: Overview of world marine fishery resources , pages 227-244, FAO Fisheries technical paper 569, FAO, Rome. ISBN: 978-92-5-107023-9.
- Identity Standard for Canned Tuna (United States), Federal Code of Regulation: 21 CFR 161.190 - Canned Tuna.
- ViÃÆ' Â ± as J and Tudela S (2009) "The methodology validated for genetic identification of the tuna species (genus Thunnus )" PLoS One , 4 (10): e7606.
External links
- Atuna.com - tuna market gate
- Benefits of tuna nutrition
- Tuna in Greenpeace
- Tuna at Stanford Microdocs University
News
- The Bluefin Tuna in Peril, Scientific American, June 24, 2008
- How Hot Tuna (and Some Sharks) Stay Warm at National Science Foundation, October 27, 2005
- Haberman, Clyde (January 25, 2008). "Tuna Fish Stories: The Candidates Spin the Sushi". The New York Times .
Source of the article : Wikipedia
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