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Thunnus

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Main article: Tuna
True tunas
Temporal range: Tertiary–holocene [1][2]
Yellowfin tuna
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Scombriformes
Family: Scombridae
Tribe: Thunnini
Genus: Thunnus
South, 1845
Subgenus

Thunnus is a genus of ocean-dwelling ray-finned bony fish from the Scombridae (Mackerel) family. More specifically, Thunnus is one of five genera which make up the Thunnini tribe – a tribe that is collectively known as the tunas. Also called the true tunas or real tunas, Thunnus consists of eight species of tuna (more than half of the overall tribe), divided into two subgenera. The word Thunnus is the Middle Latin form of the Ancient Greek: θύννος, romanized: (thýnnos), lit. 'tunny-fish' – which is in turn derived from θύνω (thynō), "to rush; to dart".[3][4] The first written use of the word was by Homer.[citation needed]

Their coloring, metallic blue on top and shimmering silver-white on the bottom, helps camouflage them from above and below. Atlantic bluefin tuna, the largest member of this genus, can grow to 15 feet (4.6 m) long and weigh up to 1,500 pounds (680 kg). All tunas are extremely strong swimmers, and the Yellowfin tuna is known to reach speeds of up to 50 miles per hour (80 km/h) when pursuing prey. As with all tunas, members of this genus are warm-blooded, which is a rare trait among fish; this enables them to tolerate cold waters. Bluefin tunas, for example, are found in Newfoundland and Iceland, and also in the tropical waters of the Gulf of Mexico and the Mediterranean Sea, where some individuals go each year to spawn.

Due to overfishing, the range of this genus has declined significantly, having been effectively removed from the Black Sea, for example.[5]

Taxonomy

Fossil specimen

This genus has eight species in two subgenera:

Relative sizes of various tunas, with the Atlantic bluefin tuna (top) at about 8 ft (2.4 m) in this sample
The True Tunas of the genus Thunnus, within the Family Scombridae
family Scombridae 
 subfamily
 subfamily
Scombrinae
tribe Scombrini 

 Mackerels (2 genera)

tribe Scomberomorini 

 Spanish Mackerels (3 genera)

tribe Sardini 

 Bonitos (4 genera)

 tribe Thunnini
Tunas 

 Allothunnus, slender tunas

 Auxis, frigate tunas

 Euthynnus, little tunas

 Katsuwonus, skipjack tunas

 Thunnus, true tunas 
 subgenus Thunnus

 bluefin group

 subgenus Neothunnus

 yellowfin group

Cladogram: Thunnus (bottom-right in image above) is one of five genera that make up the Thunnini tribe.  Known as the true tunas, it comprises 8 of the 15 extant tuna species.[1]
Maximum reported sizes of Thunnus species.

Genus membership

Until recently, it was thought that there were seven Thunnus species, and that Atlantic bluefin tuna and Pacific bluefin tuna were subspecies of a single species. In 1999 Collette established that based on both molecular and morphological considerations, they are in fact distinct species.[6][7]

The genus Thunnus is further classified into two subgenera: Thunnus (Thunnus) (the bluefin group), and Thunnus (Neothunnus) (the yellowfin group).

Thunnus, the true tunas
Image Common name Scientific name Maximum
length 		Common
length 		Maximum
weight 		Maximum
age 		Trophic
level 		Source IUCN status
Thunnus (Thunnus) – the bluefin group
Albacore tuna T. alalunga
(Bonnaterre, 1788) 		1.4 m
(4.6 ft) 		1.0 m
(3.3 ft) 		60.3 kg
(133 lb) 		9–13 yrs 4.31 [8][9] LC IUCN 3 1.svg Least Concern[9]
Southern bluefin tuna T. maccoyii
(Castelnau, 1872) 		2.45 m
(8.0 ft) 		1.6 m
(5.2 ft) 		260 kg
(570 lb) 		20–40 yrs 3.93 [10][11] EN IUCN 3 1.svg Endangered[11]
Bigeye tuna T. obesus
(Lowe, 1839) 		2.5 m
(8.2 ft) 		1.8 m
(5.9 ft) 		210 kg
(460 lb) 		5–16 yrs 4.49 [12][13] VU IUCN 3 1.svg Vulnerable[13]
Pacific bluefin tuna T. orientalis
(Temminck & Schlegel, 1844) 		3.0 m
(9.8 ft) 		2.0 m
(6.6 ft) 		450 kg
(990 lb) 		15–26 yrs 4.21 [14][15] NT IUCN 3 1.svg Near Threatened[15]
Atlantic bluefin tuna T. thynnus
(Linnaeus, 1758) 		4.6 m
(15 ft) 		2.0 m
(6.6 ft) 		684 kg
(1,508 lb) 		35–50 yrs 4.43 [16][17] LC IUCN 3 1.svg Least Concern[17]
Thunnus (Neothunnus) – the yellowfin group
Blackfin tuna T. atlanticus
(Lesson, 1831) 		1.1 m
(3.6 ft) 		0.7 m
(2.3 ft) 		22.4 kg
(49 lb) 		4.13 [18] LC IUCN 3 1.svg Least concern[19]
Longtail tuna,
northern bluefin tuna,
tongol tuna 		T. tonggol
(Bleeker, 1851) 		1.45 m
(4.8 ft) 		0.7 m
(2.3 ft) 		35.9 kg
(79 lb) 		18 years 4.50 [20][21] DD IUCN 3 1.svg Data deficient[21]
Yellowfin tuna T. albacares
(Bonnaterre, 1788) 		2.4 m
(7.9 ft) 		1.5 m
(4.9 ft) 		200 kg
(440 lb) 		5–9 yrs 4.34 [22][23] LC IUCN 3 1.svg Least Concern[23]

Overfishing

The worldwide demand for sushi and sashimi, coupled with increasing population growth, has resulted in global stocks of the species being overfished[24] and bluefin is the most endangered and considered "a serious conservation concern".[25] Complicating the efforts for sustainable management of bluefin fish stocks within national exclusive economic zones (EEZ) is bluefin migrate long distances and hunt in the mid ocean that isn't part of any country's EEZ and therefore have been vulnerable to overfishing by multiple countries' fishing fleets. International agreements and conventions are good faith agreements and are difficult to monitor or enforce.[26] Though this fish has been farmed in captivity by the Japanese and by the Australians with the help of the Japanese,[27] yields are lower than other farmed fish due to the slow growth rate of Bluefin tuna, therefore keeping prices high.[26] On December 30, 2012, a 222-kilogram (489 lb) bluefin tuna caught off northeastern Japan, was sold at the Tsukiji fish market in Tokyo for a record 155.4 million yen ($1.76 million) – a unit price of JP¥ 1.274 million/kg (US$3,600/lb).[28]

References

  1. ^ a b Graham, Jeffrey B.; Dickson, Kathryn A. (2004). "Tuna Comparative Physiology" (PDF). The Journal of Experimental Biology. 207: 4015–4024. doi:10.1242/jeb.01267. Retrieved 20 September 2012.
  2. ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: 560. Retrieved 2008-01-08.
  3. ^ θύννος in Liddell, Henry George; Scott, Robert (1940) A Greek–English Lexicon, revised and augmented throughout by Jones, Sir Henry Stuart, with the assistance of McKenzie, Roderick. Oxford: Clarendon Press. In the Perseus Digital Library, Tufts University.
  4. ^ θύνω in Liddell and Scott.
  5. ^ Hogan, C. Michael, Overfishing. Encyclopedia of Earth. eds. Sidney Draggan and Cutler Cleveland. National council for Science and the Environment, Washington DC
  6. ^ Collette, B.B. (1999). "Mackerels, molecules, and morphology". In Séret, B.; Sire, J.Y. (eds.). Proceedings. 5th Indo-Pacific Fish Conference: Nouméa, New Caledonia, 3–8 November 1997. Paris: Société Française d'Ichtyologie [u.a.] pp. 149–164. ISBN 978-2-9507330-5-4. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help)
  7. ^ Tanaka, Y.; Satoh, K.; Iwahashi, M.; Yamada, H. (2006). "Growth-dependent recruitment of Pacific bluefin tuna Thunnus orientalis in the northwestern Pacific Ocean" (PDF). Marine Ecology Progress Series. 319: 225–235. doi:10.3354/meps319225.
  8. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus alalunga". FishBase. January 2012 version.
  9. ^ a b Collette, B.; et al. (2021). "Thunnus alalunga". IUCN Red List of Threatened Species. 2021. Retrieved 29 March 2022.
  10. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus maccoyii". FishBase. January 2012 version.
  11. ^ a b Collette, B.; et al. (2021). "Thunnus maccoyii". IUCN Red List of Threatened Species. 2021. Retrieved 29 March 2022.
  12. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus obesus". FishBase. January 2012 version.
  13. ^ a b Collette, B.; et al. (2021). "Thunnus obesus". IUCN Red List of Threatened Species. 2021. Retrieved 29 March 2022.
  14. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus orientalis". FishBase. January 2012 version.
  15. ^ a b Collette, B.; et al. (2021). "Thunnus orientalis". IUCN Red List of Threatened Species. 2021. Retrieved 29 March 2022.
  16. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus thynnus". FishBase. January 2012 version.
  17. ^ a b Collette, B.; et al. (2021). "Thunnus thynnus". IUCN Red List of Threatened Species. 2021. Retrieved 9 January 2015.
  18. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus atlanticus". FishBase. January 2012 version.
  19. ^ Collette, B.; et al. (2010). "Thunnus atlanticus". IUCN Red List of Threatened Species. 2010. Retrieved 29 March 2022.
  20. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus tonggol". FishBase. January 2012 version.
  21. ^ a b Collette, B.; et al. (2009). "Thunnus tonggol". IUCN Red List of Threatened Species. 2009. Retrieved 29 March 2022.
  22. ^ Froese, Rainer; Pauly, Daniel (eds.). "Thunnus albacares". FishBase. January 2012 version.
  23. ^ a b Collette, B.; et al. (2021). "Thunnus albacares". IUCN Red List of Threatened Species. 2021. Retrieved 29 March 2022.
  24. ^ George Karleskint; Richard Turner; James Small (2009). Introduction to Marine Biology. Cengage Learning. p. 522. ISBN 0-495-56197-5.
  25. ^ "Tuna, Bluefin".
  26. ^ a b "Managed to death". The Economist. 2008-10-30.
  27. ^ Thunnus orientalis#Farming
  28. ^ "A bluefin tuna sells for record $1.76M in Tokyo". USA Today. 4 January 2013. Retrieved 5 January 2013.

Further reading

Wikimedia Commons has media related to Thunnus.


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