Difference between revisions of "Bluefin tuna" - New World Encyclopedia

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Common name of one of three species of tuna (genus **): the 888888
 
Common name of one of three species of tuna (genus **): the 888888
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{{Taxobox
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| name = Pacific bluefin tuna
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| status = VU
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| status_system = IUCN
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| image =
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| image_width = 250px
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| regnum = [[Animal]]ia
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| phylum = [[Chordate|Chordata]]
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| classis = [[Actinopterygii]]
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| ordo = [[Perciformes]]
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| familia = [[Scombridae]]
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| genus = ''[[Thunnus]]''
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| species = '''''T. orientalis'''''
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| range_map=
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| range_map_caption=
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| binomial = ''Thunnus orientalis''
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| binomial_authority = (Temminck and Schlegel, 1844)
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}}
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'''Pacific bluefin tuna''', ''Thunnus orientalis'' are some of the biggest and fastest fish in the [[Pacific Ocean]].
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<ref name="Grove">{{
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cite book
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  | last1 = Grove | first1=Jack
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  | last2 =Lavenberg  | first2=Robert
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  | title = The Fishes of the Galapagos Islands
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  | publisher = Stanford University Press
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  | date = 1997-09-01
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  | pages = 570
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  | url = http://www.amazon.com/Fishes-Galapagos-Islands-Jack-Grove/dp/0804722897
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  | isbn = 978-0804722896}}</ref>
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They possess streamlined bodies to reduce water resistance and conserve energy for trans-Pacific migrations. Retractable [[fin]]s also allow a freer flow of water when navigation does not require their use.
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==Physiology==
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===Thermoregulation===
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Most fish are cold-blooded ([[ectothermic]]).
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<ref name="Purves">{{
 +
cite book
 +
  | last1=Purves | first1=William
 +
  | last2=Sadava | first2 = David
 +
  | last3=Orians | first3 = Gordon
 +
  | last4=Heller | first4 =H. Craig
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  | title = Life: The Science of Biology, Sixth Edition
 +
  | publisher = W. H. Freeman
 +
  | date = December 15, 2000
 +
  | pages = 704
 +
  | url = http://www.amazon.com/Life-Science-William-K-Purves/dp/0716738732
 +
  | isbn =978-0716738732}}</ref>
 +
However, [[tuna]] and [[Lamniformes|mackerel sharks]] are [[warm-blooded]]: they can regulate their body temperature. Warm-blooded fish possess organs near their [[muscles]] called ''[[rete mirabile|retia mirabilia]]'' that consist of a series of minute parallel [[vein]]s and [[artery|arteries]] that supply and drain the muscles. As the warmer blood in the [[vein]]s returns to the [[gill]]s for fresh [[oxygen]] it comes into close contact with cold, newly oxygenated blood in the [[artery|arteries]]. The system acts as a counter-current heat exchanger and the heat from the blood in the veins is given up to the colder arterial blood rather than being lost at the gills. The net effect is an increase in temperature. Fish from warmer water elevate their temperature a few degrees whereas those from cold water may raise it as much as {{convert|20|C-change|F-change|0}} warmer than the surrounding sea.
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The tuna's ability to maintain body temperature has several definite advantages over other sea life. It need not limit its range according to water temperature, nor is it dominated by climactic changes. The additional heat supplied to the muscles is also advantageous because of the resulting extra power and speed.  Bluefin tuna have been clocked in excess of {{convert|30|mph|km/h}} during 10 to 20 second sprints, enabling it to hunt [[squid]], [[herring]], [[mackerel]], etc., that slower predators cannot capture.
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==Distribution==
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[[Pacific]] bluefin tuna spawn in the Western Pacific between [[Okinawa]] and the [[Philippines]] and probably the [[Sea of Japan]]. They migrate over 6,000 nautical miles (11,000&nbsp;km) to the Eastern Pacific, eventually returning to their birth waters to spawn again.
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==Life history==
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Bluefin tuna mature slowly, reaching sexual maturity at about 5 years of age, with a maximum lifespan believed to be about 25 years.<ref name="MBA-SFW"/>  Pacific bluefin tuna have been recorded to reach {{f to m|9}} in fork length and can weigh over {{lb to kg|1000}}.<ref>http://fishbull.noaa.gov/951/crockford.pdf</ref> They eat smaller fish, [[krill]], [[pelagic red crab]], [[mackerel]] and [[squid]].
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==Conservation status==
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Pacific Bluefin Tuna are overfished throughout their range.
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<ref name="MBA-SFW">{{cite web
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  | last = Cascorbi
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  | first = Alice
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  | title = Seafood Watch Seafood Report: Tunas
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  | publisher = Monterey Bay Aquarium
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  | date = 2003-10-31
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  | url = http://www.montereybayaquarium.org/cr/SeafoodWatch/web/sfw_factsheet.aspx?fid=60
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  | accessdate = 2009-02-21 }}</ref>
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They are hooked on [[long line fishing|long lines]] or illegally netted where they swim, and many young bluefin are captured before they reproduce.{{Citation needed|date=December 2010}} Creating effective fishing policies is difficult because they are migratory, swimming through the territorial waters of many different nations. Data about their movements and high levels of international cooperation are needed to ensure sustainable populations.
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It is estimated by some that from 1976 to 2006 worldwide stocks of Bluefin Tuna plummeted by 90%.{{Citation needed|date=December 2010}} Most [[Sustainable seafood advisory lists and certification#Guides and advisory lists|seafood sustainability guides]] recommend consumers choose alternatives to bluefin tuna.
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In 2010, [[Greenpeace International]] added this population to its seafood red list, saying:
 +
:"The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."<ref>
 +
http://www.greenpeace.org/international/seafood/red-list-of-species Greenpeace International Seafood Red list</ref>
 +
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==Environmental issues==
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The blue fin tuna industry has been on the rise since the 1950s, and during the 1970s it hit a rapid increase in demand. This increase in demand for tuna has led to an equally rapid decline in their population. The number of tuna has hit such an alarmingly low number that they have been put on various endangered species lists. There has been a movement by Monaco to encourage the UN [[Convention on International Trade in Endangered Species]] (CITES) to officially put bluefin tuna on the Annex List of Threatened Species.
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* '''What Monaco’s goal would change:''' This would grant the fish the highest level of international protection. Tuna would be limited to domestic markets only, and absolutely no international trade of the fish or their parts. Since the commercial fishing habits began for bluefin tuna in the 1950s their populations have been estimated to have dropped by anywhere from 75% to as high as 97%. Some conservation groups have predicted their extinction within the next 12 years if current fishing levels don’t diminish. This becomes a problem for a few reasons, one is the fact of extinction, but also what that means for the health and well being of the ocean. Tuna are one of the larger predators found in southern parts of the ocean, and their extinction could mean an overpopulation of many smaller species such as [[crustaceans]], [[squid]], and [[eels]] (National Geographic, 2010).
 +
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* '''The [[International Commission for the Conservation of Atlantic Tunas]] (ICCAT) and its influence:''' ICCAT is considered to be “the manager” of the bluefin tuna{{Citation needed|date=May 2010}}. They have raised some concerns for conservation groups because ICCAT has set quotas that often double the levels recommended by scientists. At times fishing exceeds even these quota levels. This concern is also mentioned in Monaco’s application to CITES (Gronewold, 2009). The bluefin tuna industry is posing some serious threats to the tuna population through overfishing and opposition to stricter regulations. It also provides a significant income for some countries{{Citation needed|date=May 2010}}.
 +
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* '''Players in the tuna industry:''' The biggest importer is Japan, claiming 90% of the global bluefin catch.<ref name="pbs.org">http://www.pbs.org/safarchive/3_ask/archive/qna/3285_hdewarandtwillams.html</ref> Their imports in 2007 were about 32,356 tons of tuna{{Citation needed|date=May 2010}}. Occasionally, an individual fish can sell in a Japanese fish market for prices greater than 100,000 USD, but the average price is closer to 10,000 USD.<ref name="pbs.org"/> Like many other scarce resources, bluefin tuna’s prices have increased as their populations decrease. In 2002, tuna was the third most valuable export in the fishing business (globefish, org, 2008), giving little incentive for exporters to limit their catch. Some of the larger exporters of 2002 were Taiwan, Indonesia, and Japan. The tuna industry overall brings billions of dollars of revenue for various regions around the world, and while bluefin makes the smallest percentage of all the hunted species of tuna, it also makes the most money per pound.
 +
 +
* '''Effects of protection policies:''' Some individual countries have put regulations on the fishing of bluefin; the downside is unemployment of local fishermen{{Citation needed|date=May 2010}}. There are concerns that arise from attempting to implement an umbrella policy such as Monaco is proposing: Tuna port countries, many of which are found in the southern hemisphere, are concerned for their fishermen, as well as their source of income{{Citation needed|date=May 2010}}.
 +
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==Farming==
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[[Japan]] is both the biggest consumer and the leader in over tuna farming research.<ref>
 +
http://www.livescience.com/animals/080317-sl-tuna-farming.html</ref><ref>Ito, Masami, "[http://search.japantimes.co.jp/cgi-bin/nn20100831i1.html Does Japan's affair with tuna mean loving it to extinction?]", ''[[Japan Times]]'', August 31, 2010, p. 3.</ref> [[Kinki University]] of Japan first successfully farmed already-hatched bluefin tuna in 1979. In 2002, they succeeded in breeding them, and in 2007, the process was repeated for a third generation.<ref>{{
 +
Cite news |url=http://www.taipeitimes.com/News/editorials/archives/2006/09/30/2003329854 |title=The holy grail of fish breeding}}</ref><ref>
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http://www.flku.jp/english/aquaculture/index.html</ref><ref>{{cite news| url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/05/21/FDI910LR9P.DTL&type=printable | work=The San Francisco Chronicle | first=Carolyn | last=Jung | date=2008-05-21}}</ref> This farm-raised tuna is now known as Kindai tuna. Kindai is a contraction of Kinki University (Kinki daigaku).<ref>
 +
http://nymag.com/restaurants/features/46633/</ref> In 2009, Clean Seas, an Australian company with assistance from Kinki University <ref>
 +
http://www.fnarena.com/index2.cfm?type=dsp_newsitem&n=4213142B-1871-E587-E13DAA02FD0A4316] [http://www.abc.net.au/cgi-bin/common/printfriendly.pl?http://www.abc.net.au/stateline/sa/content/2005/s1509579.htm</ref><ref>{{
 +
Cite news|url=http://www.news.com.au/adelaidenow/story/0,22606,24389186-913,00.html|title=Clean Seas teams up with Japan's Kinki Uni for tuna research | work=The Advertiser | first=Nigel | last=Austin | date=2008-09-23}}</ref> managed to breed Southern Bluefin Tuna in captivity, leading [[Time Magazine]] to award it second place in World’s Best Invention of 2009.<ref>
 +
{{cite news| url=http://www.time.com/time/specials/packages/article/0,28804,1934027_1934003_1933946,00.html | work=Time | title=The 50 Best Inventions Of 2009 | date=2009-11-12 | accessdate=2010-05-20}}</ref><ref>
 +
http://www.thinkingaustralia.com/news/brief_view.asp?id=1525</ref>
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==References==
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{{reflist}}
 +
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==External links==
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{{wikispecies|Thunnus orientalis}}
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{{Commons category|Thunnus orientalis}}
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* [http://www.economist.com/background/displaystory.cfm?story_id=12502783 Bye bye bluefin: Managed to death] The Economist. 30 October 2008. Retrieved 6 February 2009.
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* [http://topp.org/features/topp_and_bluefin_tuna/ TOPP, Tagging of Pacific Predators], a research group that tags and tracks the amazing Pacific bluefin tuna to learn more about it. The site features information, photos, blog posts and multimedia stories about the bluefin tuna.
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{{commercial fish topics}}
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{{DEFAULTSORT:Pacific Bluefin Tuna}}
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[[Category:Fishes]]
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[[Category:Animals]]
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[[Category:Life sciences]]
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[[Category:Food]]
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{{credit|Pacific_bluefin_tuna|420479222}}

Revision as of 15:57, 18 April 2011

Common name of one of three species of tuna (genus **): the 888888

Pacific bluefin tuna
Conservation status
200px
Vulnerable

(IUCN)

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Scombridae
Genus: Thunnus
Species: T. orientalis
Binomial name
Thunnus orientalis
(Temminck and Schlegel, 1844)

Pacific bluefin tuna, Thunnus orientalis are some of the biggest and fastest fish in the Pacific Ocean. [1] They possess streamlined bodies to reduce water resistance and conserve energy for trans-Pacific migrations. Retractable fins also allow a freer flow of water when navigation does not require their use.

Physiology

Thermoregulation

Most fish are cold-blooded (ectothermic). [2] However, tuna and mackerel sharks are warm-blooded: they can regulate their body temperature. Warm-blooded fish possess organs near their muscles called retia mirabilia that consist of a series of minute parallel veins and arteries that supply and drain the muscles. As the warmer blood in the veins returns to the gills for fresh oxygen it comes into close contact with cold, newly oxygenated blood in the arteries. The system acts as a counter-current heat exchanger and the heat from the blood in the veins is given up to the colder arterial blood rather than being lost at the gills. The net effect is an increase in temperature. Fish from warmer water elevate their temperature a few degrees whereas those from cold water may raise it as much as Template:Convert/C-change warmer than the surrounding sea.

The tuna's ability to maintain body temperature has several definite advantages over other sea life. It need not limit its range according to water temperature, nor is it dominated by climactic changes. The additional heat supplied to the muscles is also advantageous because of the resulting extra power and speed. Bluefin tuna have been clocked in excess of 30 miles per hour (48 km/h) during 10 to 20 second sprints, enabling it to hunt squid, herring, mackerel, etc., that slower predators cannot capture.

Distribution

Pacific bluefin tuna spawn in the Western Pacific between Okinawa and the Philippines and probably the Sea of Japan. They migrate over 6,000 nautical miles (11,000 km) to the Eastern Pacific, eventually returning to their birth waters to spawn again.

Life history

Bluefin tuna mature slowly, reaching sexual maturity at about 5 years of age, with a maximum lifespan believed to be about 25 years.[3] Pacific bluefin tuna have been recorded to reach Template:F to m in fork length and can weigh over 1,000 pounds (454 kg).[4] They eat smaller fish, krill, pelagic red crab, mackerel and squid.

Conservation status

Pacific Bluefin Tuna are overfished throughout their range. [3] They are hooked on long lines or illegally netted where they swim, and many young bluefin are captured before they reproduce.[citation needed] Creating effective fishing policies is difficult because they are migratory, swimming through the territorial waters of many different nations. Data about their movements and high levels of international cooperation are needed to ensure sustainable populations.

It is estimated by some that from 1976 to 2006 worldwide stocks of Bluefin Tuna plummeted by 90%.[citation needed] Most seafood sustainability guides recommend consumers choose alternatives to bluefin tuna.

In 2010, Greenpeace International added this population to its seafood red list, saying:

"The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."[5]

Environmental issues

The blue fin tuna industry has been on the rise since the 1950s, and during the 1970s it hit a rapid increase in demand. This increase in demand for tuna has led to an equally rapid decline in their population. The number of tuna has hit such an alarmingly low number that they have been put on various endangered species lists. There has been a movement by Monaco to encourage the UN Convention on International Trade in Endangered Species (CITES) to officially put bluefin tuna on the Annex List of Threatened Species.

  • What Monaco’s goal would change: This would grant the fish the highest level of international protection. Tuna would be limited to domestic markets only, and absolutely no international trade of the fish or their parts. Since the commercial fishing habits began for bluefin tuna in the 1950s their populations have been estimated to have dropped by anywhere from 75% to as high as 97%. Some conservation groups have predicted their extinction within the next 12 years if current fishing levels don’t diminish. This becomes a problem for a few reasons, one is the fact of extinction, but also what that means for the health and well being of the ocean. Tuna are one of the larger predators found in southern parts of the ocean, and their extinction could mean an overpopulation of many smaller species such as crustaceans, squid, and eels (National Geographic, 2010).
  • The International Commission for the Conservation of Atlantic Tunas (ICCAT) and its influence: ICCAT is considered to be “the manager” of the bluefin tuna[citation needed]. They have raised some concerns for conservation groups because ICCAT has set quotas that often double the levels recommended by scientists. At times fishing exceeds even these quota levels. This concern is also mentioned in Monaco’s application to CITES (Gronewold, 2009). The bluefin tuna industry is posing some serious threats to the tuna population through overfishing and opposition to stricter regulations. It also provides a significant income for some countries[citation needed].
  • Players in the tuna industry: The biggest importer is Japan, claiming 90% of the global bluefin catch.[6] Their imports in 2007 were about 32,356 tons of tuna[citation needed]. Occasionally, an individual fish can sell in a Japanese fish market for prices greater than 100,000 USD, but the average price is closer to 10,000 USD.[6] Like many other scarce resources, bluefin tuna’s prices have increased as their populations decrease. In 2002, tuna was the third most valuable export in the fishing business (globefish, org, 2008), giving little incentive for exporters to limit their catch. Some of the larger exporters of 2002 were Taiwan, Indonesia, and Japan. The tuna industry overall brings billions of dollars of revenue for various regions around the world, and while bluefin makes the smallest percentage of all the hunted species of tuna, it also makes the most money per pound.
  • Effects of protection policies: Some individual countries have put regulations on the fishing of bluefin; the downside is unemployment of local fishermen[citation needed]. There are concerns that arise from attempting to implement an umbrella policy such as Monaco is proposing: Tuna port countries, many of which are found in the southern hemisphere, are concerned for their fishermen, as well as their source of income[citation needed].

Farming

Japan is both the biggest consumer and the leader in over tuna farming research.[7][8] Kinki University of Japan first successfully farmed already-hatched bluefin tuna in 1979. In 2002, they succeeded in breeding them, and in 2007, the process was repeated for a third generation.[9][10][11] This farm-raised tuna is now known as Kindai tuna. Kindai is a contraction of Kinki University (Kinki daigaku).[12] In 2009, Clean Seas, an Australian company with assistance from Kinki University [13][14] managed to breed Southern Bluefin Tuna in captivity, leading Time Magazine to award it second place in World’s Best Invention of 2009.[15][16]

References
ISBN links support NWE through referral fees

  1. ↑ (1997-09-01) The Fishes of the Galapagos Islands. Stanford University Press, 570. ISBN 978-0804722896. 
  2. ↑ (December 15, 2000) Life: The Science of Biology, Sixth Edition. W. H. Freeman, 704. ISBN 978-0716738732. 
  3. ↑ 3.0 3.1 Cascorbi, Alice (2003-10-31). Seafood Watch Seafood Report: Tunas. Monterey Bay Aquarium. Retrieved 2009-02-21.
  4. ↑ http://fishbull.noaa.gov/951/crockford.pdf
  5. ↑ http://www.greenpeace.org/international/seafood/red-list-of-species Greenpeace International Seafood Red list
  6. ↑ 6.0 6.1 http://www.pbs.org/safarchive/3_ask/archive/qna/3285_hdewarandtwillams.html
  7. ↑ http://www.livescience.com/animals/080317-sl-tuna-farming.html
  8. ↑ Ito, Masami, "Does Japan's affair with tuna mean loving it to extinction?", Japan Times, August 31, 2010, p. 3.
  9. ↑ "The holy grail of fish breeding".
  10. ↑ http://www.flku.jp/english/aquaculture/index.html
  11. ↑ Template error: argument title is required.
  12. ↑ http://nymag.com/restaurants/features/46633/
  13. ↑ http://www.fnarena.com/index2.cfm?type=dsp_newsitem&n=4213142B-1871-E587-E13DAA02FD0A4316] [http://www.abc.net.au/cgi-bin/common/printfriendly.pl?http://www.abc.net.au/stateline/sa/content/2005/s1509579.htm
  14. ↑ Austin, Nigel, "Clean Seas teams up with Japan's Kinki Uni for tuna research", The Advertiser, 2008-09-23.
  15. ↑ "The 50 Best Inventions Of 2009", Time, 2009-11-12. Retrieved 2010-05-20.
  16. ↑ http://www.thinkingaustralia.com/news/brief_view.asp?id=1525

External links

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