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Skipjack tuna

The skipjack tuna (Katsuwonus pelamis) is a perciform fish in the tuna family, Scombridae, and is the only member of the genus Katsuwonus. It is also known as katsuo, arctic bonito, mushmouth, oceanic bonito, striped tuna or victor fish. It grows up to 1 m (3 ft) in length. It is a cosmopolitan pelagic fish found in tropical and warm-temperate waters. It is a very important species for fisheries.[2] It is also the namesake of the USS Skipjack.

Description

Shoaling skipjack tuna

It is a streamlined, fast-swimming pelagic fish common in tropical waters throughout the world, where it inhabits surface waters in large shoals (up to 50,000 fish), feeding on fish, crustaceans, cephalopods, and mollusks. It is an important prey species for sharks and large pelagic fishes and is often used as live bait when fishing for marlin. It has no scales, except on the lateral line and the corselet (a band of large, thick scales forming a circle around the body behind the head). It commonly reaches fork lengths up to 80 cm (2 ft 7 in) and a mass of 8–10 kg (18–22 lb). Its maximum fork length is 108 cm (3 ft 7 in), and its maximum mass is 34.5 kg (76 lb). Determining the age of skipjack tuna is difficult, and estimates of its potential lifespan range between 8 and 12 years.[2]

Skipjack tuna are batch spawners. Spawning occurs year-round in equatorial waters, but it gets more seasonal further away from the equator. Fork length at first spawning is about 45 cm (18 in). It is also known for its potent smell.[2]

Skipjack tuna has the highest percentage of skeletal muscle devoted to locomotion of all animals, at 68% of the animal's total body mass.[3][4]

Skipjack tuna are highly sensitive to environmental conditions and changes. Climate change effects are significant in marine ecosystems, and ecological factors may change fish distribution and catchability.[5]

Fisheries

Worldwide capture of skipjack tuna in tonnes reported by the FAO
Bell M. Shimada and Fred Cleaver examining skipjack tuna

It is an important commercial and game fish, usually caught using purse seine nets, and is sold fresh, frozen, canned, dried, salted, and smoked. In 2018, landings of 3.2 million tonnes were reported, the third highest of any marine capture fishery (after Peruvian anchoveta and Alaska pollock).[6]Countries recording large amounts of skipjack catches include the Maldives, France, Spain, Malaysia, Sri Lanka, and Indonesia.[7]

Skipjack is the most fecund of the main commercial tunas, and its population is considered sustainable against its current consumption.[8][9] Its fishing is still controversial due to the methodology, with rod and reel or fishery options being promoted as ecologically preferable.[10][11][12] Purse seine methods are considered unsustainable by some authorities due to excess bycatch, although bycatch is said to be much reduced if fish aggregation devices are not used.[13] These considerations have led to the availability of canned skipjack marked with the fishing method used to catch it.[14]

Skipjack is considered to have "moderate" mercury contamination. As a result, pregnant women are advised against eating large quantities.[15][16][17] In addition, skipjack's livers were tested globally for tributyltin (TBT) contamination. TBT is an organotin compound introduced into marine ecosystems through antifouling paint used on ship hulls and has been determined to be very toxic. About 90% of skipjack tested positive for contamination, especially in Southeast Asia, where regulations of TBT use are less rigorous than in Europe or the US.[18]

As food

Katsuo Fish with Cherry Buds, print by Utagawa Hiroshige, 1830s

Japan

Skipjack tuna is used extensively in Japanese cuisine, where it is known as katsuo (鰹/かつお). It is eaten raw in sushi and sashimi, as well as slightly seared in katsuo tataki. It is also smoked and dried to make katsuobushi, and the shavings are commonly used to make dashi (soup stock).[19] Katsuobushi flakes are also used as seasoning, such as in onigiri (rice balls) or on top of tofu. The raw viscera of skipjack tuna is salted and fermented to make shutō, a type of shiokara.

The fish's fat content changes during migrations along the Japanese islands. When they migrate north in summer, they are called hatsugatsuo ("first katsuo") or noborigatsuo ("ascending katsuo"), and have a lesser amount of fat. When they migrate south in autumn, they are called modorigatsuo ("returning katsuo") or kudarigatsuo ("descending katsuo"), and have a high level of fat.

Other places

In Indonesian cuisine, skipjack tuna is known as cakalang. The most popular Indonesian dish made from skipjack tuna is cakalang fufu from Minahasa. It is a cured and smoked skipjack tuna dish, made by cooking the fish after clipping it to a bamboo frame.[20] Skipjack known as kalhubilamas in Maldives is integral to Maldivian cuisine.[21]

Skipjack tuna is an important fish in the native cuisine of Hawaii (where it is known as aku) and throughout the Pacific islands. Hawaiians prefer to eat aku either raw as a sashimi or poke or seared in Japanese tataki style.[22]

The trade in pickled skipjack tuna is a driving force behind the commercial fishery of this species in Spain.[23]

References

  1. ^ Collette, B.; Acero, A.; Amorim, A.F.; et al. (2011). "Katsuwonus pelamis". The IUCN Red List of Threatened Species. 2011: e.T170310A6739812. doi:10.2305/IUCN.UK.2011-2.RLTS.T170310A6739812.en.
  2. ^ a b c Collette, Bruce B.; Cornelia E. Nauen (1983). FAO species catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and other related species known to date (PDF). FAO Fisheries Synopsis. Rome: Food and Agriculture Organization of the United Nations. p. 137.
  3. ^ Calder, William A. (1996). Size, Function, and Life History. Courier Corporation. p. 19. ISBN 978-0-486-69191-6.
  4. ^ Bone, Q. (1978). Locomotor muscle. Fish physiology: Academic Press. p. 362. ISBN 978-0-08-058527-7.
  5. ^ Yen, Kuo-Wei; Su, Nan-Jay; Teemari, Tooreka; Lee, Min-An; Lu, Hsueh-Jung (2016-12-01). "PREDICTING THE CATCH POTENTIAL OF SKIPJACK TUNA IN THE WESTERN AND CENTRAL PACIFIC OCEAN UNDER DIFFERENT CLIMATE CHANGE SCENARIOS". Journal of Marine Science and Technology. 24 (6). doi:10.6119/JMST-016-0713-1. ISSN 1023-2796.
  6. ^ The State of World Fisheries and Aquaculture 2020. Food and Agriculture Organization. 2022. doi:10.4060/cc0461en. hdl:10535/3776. ISBN 978-92-5-136364-5. Archived from the original on 2022-03-04. Retrieved 2022-03-08 – via fao.org.
  7. ^ Makoto Miyake; Naozumi Miyabe; Hideki Nakano (2004). Historical trends of tuna catches in the world. FAO Fisheries Technical Paper No. 467. Rome: Food and Agriculture Organization of the United Nations.
  8. ^ "FishWatch: Atlantic Skipjack Tuna (Katsuwonus pelamis)". NOAA.gov. National Oceanic and Atmospheric Administration. November 3, 2009. Retrieved 2009-11-12.
  9. ^ "Skipjack tuna, purse seine caught". blueocean.org. Blue Ocean Institute. November 11, 2009. Archived from the original on 2010-06-13. Retrieved 2009-11-12.
  10. ^ "BUSINESS: PACIFIC TOLD TO TAKE THE LEAD If region wants to conserve critical resource". Islands Business International. November 2009. Retrieved 2009-11-12.
  11. ^ "Pacific tries to show way in sustainable tuna fishing". ABC International - Radio Australia. October 23, 2009. Retrieved 2009-11-12.
  12. ^ "Retailers' Guide to Sustainable and Equitable Pole and Line Skipjack". greenpeace.org. Greenpeace International. 27 April 2009. Retrieved 2009-11-12.
  13. ^ "Tuna, Skipjack". SeafoodWatch.org. Monterey Bay Aquarium. Archived from the original on 2014-08-19. Retrieved 2014-08-16.
  14. ^ Schwartz, Ariel (2012-09-30). "How Safeway Ended Up Selling Cheap, Responsibly-Caught Store Brand Tuna". Fast Company. Retrieved 2014-08-16.
  15. ^ "Mercury Levels in Sushi". americanpregnancy.org. Retrieved 2013-08-22.
  16. ^ "Mercury Levels in Fish". NRDC.org. Retrieved 2013-08-22.
  17. ^ "Advice for Pregnant Women on Fish Consumption concerning Mercury Contamination". mhlw.go.jp. 2003-06-03. Retrieved 2013-08-22.
  18. ^ Down, Steve. "Tuna is attuned to tin". separationsnow.com. Retrieved 2014-04-28.
  19. ^ Naomichi, Ishige (2014). The History and Culture of Japanese Food. Routledge. p. 14. ISBN 978-0710306579.
  20. ^ "Cakalang Fufu Jadi Pilihan di Sulut" (in Indonesian). MediaIndonesia.com. 15 July 2011. Archived from the original on 1 January 2013. Retrieved 1 June 2012.
  21. ^ Prince, Rose (11 March 2010). "Tuna fishing in the Maldives: the fairest catch". The Telegraph. Retrieved 13 April 2011.
  22. ^ "Skipjack Tuna (Aku)". Hawaii Seafood. Retrieved 2020-01-14.
  23. ^ Pesca y Acuicultura

Sources

External links