Jump to content

Oceanic whitetip shark: Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
No edit summary
m Fixed a typo
Line 32: Line 32:
The '''oceanic whitetip shark''' ('''''Carcharhinus longimanus''''') is a large [[pelagic zone|pelagic]] [[requiem shark]] inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded [[Pectoral fins|fins]]. The species is typically solitary, though they may gather in large numbers at food concentrations. Bony fish and [[cephalopod]]s are the main components of its diet and females give [[viviparous|live birth]].
The '''oceanic whitetip shark''' ('''''Carcharhinus longimanus''''') is a large [[pelagic zone|pelagic]] [[requiem shark]] inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded [[Pectoral fins|fins]]. The species is typically solitary, though they may gather in large numbers at food concentrations. Bony fish and [[cephalopod]]s are the main components of its diet and females give [[viviparous|live birth]].


Though slow-moving, it is opportunistic and aggressive, and is reputed to be dangerous to shipwreck survivors. Oceanic whitetips appear to be able to survive in captivity better than other open ocean sharks. The [[IUCN Red List]] considers the species to be [[critically endangered]]. Recent studies show steeply declining populations as they are harvested for their fins, meat. As with other shark species, the whitetip faces mounting [[fishery|fishing]] pressure throughout its range.
Though slow-moving, it is opportunistic and aggressive, and is reputed to be dangerous to shipwreck survivors. Oceanic whitetips appear to be able to survive in captivity better than other open ocean sharks. The [[IUCN Red List]] considers the species to be [[critically endangered]]. Recent studies show steeply declining populations as they are harvested for their fins and meat. As with other shark species, the whitetip faces mounting [[fishery|fishing]] pressure throughout its range.


==Taxonomy==
==Taxonomy==

Revision as of 00:55, 25 February 2023

Oceanic whitetip shark
Female individual surrounded by pilot fish in the Red Sea
CITES Appendix II (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species:
C. longimanus
Binomial name
Carcharhinus longimanus
(Poey, 1861)
Range of the oceanic whitetip shark
Synonyms[3]
  • Carcharias obtusus (Garman, 1881)
  • Squalus longimanus Poey, 1861
  • Carcharias longimanus (Poey, 1861)
  • Pterolamiops longimanus (Poey, 1861)
  • Carcharinus longimanus (Poey, 1861)
  • Squalus maou (Lesson, 1831)
  • Carcharhinus maou (Lesson, 1831)
  • Carcharias insularum (Snyder, 1904)
  • Pterolamiops magnipinnis (Smith, 1958)
  • Pterolamiops budkeri (Fourmanoir, 1961)

The oceanic whitetip shark (Carcharhinus longimanus) is a large pelagic requiem shark inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded fins. The species is typically solitary, though they may gather in large numbers at food concentrations. Bony fish and cephalopods are the main components of its diet and females give live birth.

Though slow-moving, it is opportunistic and aggressive, and is reputed to be dangerous to shipwreck survivors. Oceanic whitetips appear to be able to survive in captivity better than other open ocean sharks. The IUCN Red List considers the species to be critically endangered. Recent studies show steeply declining populations as they are harvested for their fins and meat. As with other shark species, the whitetip faces mounting fishing pressure throughout its range.

Taxonomy

The oceanic whitetip shark, or lesser white shark, was described in 1831 by naturalist René-Primevère Lesson, who named the shark Carcharhinus maou. It was next described by Cuban Felipe Poey in 1861 as Squalus longimanus.[4] The name Pterolamiops longimanus has also been used. The species epithet longimanus refers to the size of its pectoral fins (longimanus means "long fingers" in Latin). The oceanic whitetip shark is called many things in English: Brown Milbert's sand bar shark, brown shark, nigano shark, oceanic white-tipped whaler, and whitetip shark.[5]

The rules of the International Commission on Zoological Nomenclature are that in general the first-published description has priority; therefore, the valid scientific name for the oceanic whitetip shark should be Carcharhinus maou. However, Lesson's name remained forgotten for so long that Carcharhinus longimanus remains widely accepted.[6]

Distribution and habitat

The oceanic whitetip is found globally in deep, open oceans, with a temperature greater than 18 °C (64 °F),[3] It prefers water temperatures above 20 °C (68 °F), and up to 28 °C (82 °F) but can also be found in waters as cool as 15 °C (59 °F) but avoids temperatures lower than this.[6][7] It was once extremely common and widely distributed, and still inhabits a wide band around the globe; however, recent studies suggest that its numbers have drastically declined.[8]

It is found worldwide between 45°N and 43°S latitude.[3] In September 2004, a 2.3 m (7.5 ft) vagrant oceanic whitetip shark was seen in the brackish waters of Gullmarsfjorden in Sweden; it died shortly after.[9][10] This is the only North European record and far north of its usual range limit.[9]

The shark spends most of its time in the upper layer of the ocean—to a depth of 150 m (490 ft)[3]—and prefers off-shore, deep-ocean areas. According to longline capture data, increasing distance from land correlates to a greater population of sharks.[5] It is sometimes found close to land, in waters as only 37 m (120 ft), mainly around oceanic islands and narrow continental shelves.[6]

Description

C. longimanus' most distinguishing characteristics are its long, wing-like pectoral and dorsal fins. The fins are significantly larger than most other shark species, and are conspicuously rounded. The shark's snout is rounded and its eyes are circular, with nictitating membranes.[5]

Oceanic whitetip jaws

The oceanic whitetip shark is a robust, large-bodied shark. The largest specimen ever caught measured 4 m (13 ft), though they usually grow to no more than 3 m (9.8 ft). It can weigh as much as 170 kg (370 lb). The female is typically larger than the male by 10 cm (3.9 in).[5][6] In the Gulf of Mexico in the 1950s, the mean weight of oceanic whitetip sharks was 86.4 kg (190 lb). In the 1990s, the sharks of the species from the same area averaged only 56.1 kg (124 lb).[11]

The species is grey-bronze dorsally and white ventrally.[6] As its name suggests, most of its fins (dorsal, pectoral, pelvic and caudal) have white tips. Along with white tips, the fins may be mottled, and young specimens can have black marks. A saddle-like patch may be apparent between first and second dorsal fins. The shark has two kinds of teeth. Those in the mandible (lower jaw) have are thinner with a serrated tip. Between 13 and 15 teeth are on either side of the jaw. The teeth in the upper jaw are triangular, but much larger and wider with entirely serrated edges—14 or 15 occur along each side. The denticles are nearly flat and wide, typically have between five and seven ridges. There is little overlap between them, revealing some skin.[5]

Behaviour

Shark accompanied by group of fish with black and white vertical stripes and split tail fin
Oceanic whitetip photographed at the Elphinstone reef, Red Sea, Egypt, accompanied by pilot fish

The oceanic whitetip is typically solitary, though gatherings have been observed where food is plentiful.[6] It swims during the day and night. The oceanic whitetip is usually solitary and slow-moving and tends to cruise near the top of the water column in open water.[5] During summer, when the water surface is warmer, oceanic whitetips tend to swim at deeper depths with a faster pace.[12] They have been observed to breach out of the water.[13]

The species feeds mainly on pelagic cephalopods, like squid, and bony fish,[3] such as lancetfish, oarfish, barracuda, jacks, mahi-mahi, marlin, tuna, and mackerel. However, its diet can be far more varied and less selective—it is known to eat threadfins, stingrays, sea turtles, birds, gastropods, crustaceans, and dead mammals. Its feeding methods include swimming through schools of frenzied tuna with an open mouth and waiting for the fish to swim in before biting down. When whaling took place in warm waters, oceanic whitetips were the most common scavengers of floating carcasses. Whitetips commonly compete for food with silky sharks, making up for its comparatively leisurely swimming style with aggressive displays.[6] They are known to trail pilot whales since they both feed on squid.[5][14]

Pilot fish, dolphinfish, and remora may follow these sharks.[5] Evidence in the form of sucker scars on the skin of an individual filmed off Hawaii indicate that the species may also dive deep enough to battle with giant squid.[15] Until the 16th century, sharks were known to mariners as "sea dogs"[16] and the oceanic whitetip, the most common ship-following shark. Groups often form when individuals converge on a food source. They are recorded to segregate by both sex and size. They commonly get into feeding frenzies.[6] Oceanic whitetips gather in large numbers off Cat Island, Bahamas from winter to spring, due to the abundance of large bony fish.[14]

Lifecycle

Mating and birthing seems to occur in early summer in the northwest Atlantic Ocean and southwest Indian Ocean, although females captured in the Pacific have been found with embryos year round, suggesting a longer mating season there.[6] The shark is viviparous—embryos develop in utero and are fed by a placental sac. Its gestation period lasts nine months to one year.[7][17] In the northwest Atlantic, shark pups are born 65–75 cm (26–30 in) long while off South Africa, birth length is 60–65 cm (24–26 in) long.[7] In the Pacific Ocean, newborns average 45–55 cm (18–22 in) long, and number two to fourteen per litter.[17]

In one population off Brazil, sharks were recorded to grow an average of 25.2 cm (9.9 in) in one year, reducing to 13.6 cm (5.4 in) per year up to four years and then 9.7 cm (3.8 in) in their fifth year. Both sexes reached maturity at 180–190 cm (71–75 in) between the ages of six and seven and continued to grow at 9.10 cm (3.58 in) per year.[18] The average length of maturity for sharks averages in the greater equatorial and southwestern Atalntic is 170 cm (67 in) for females and 170–190 cm (67–75 in) for males.[19] In the Pacific, sharks appear to mature at four to five years.[17] One oceanic whitetip shark was estimated to have lived 22 years.[5]

Interactions with humans

Oceanic whitetip shark swimming near a driver in the Red Sea

Oceanographic researcher Jacques Cousteau described the oceanic whitetip as "the most dangerous of all sharks".[20] Author and big-game fisherman Ernest Hemingway depicted them as aggressive opportunists that attacked the catch of fishermen.[21] After the USS Indianapolis was torpedoed on 30 July 1945, most sailors who survived the sinking reportedly died from exposure to the elements rather than from shark bites.[22] However, according to survivor accounts published in several books about sharks and shark attacks, potentially hundreds of the Indianapolis crew were eventually killed by sharks before a plane spotted them on the 5th day after the sinking. Oceanic whitetips are believed to have been responsible for most if not all of those attacks.[23][24] Also during World War II, the RMS Nova Scotia, a steamship carrying about 1,000 people near South Africa, was sunk by a German submarine. One hundred and ninety-two people survived; many deaths were attributed to the whitetip.[25] Subsequently, the species is recorded to have attacked 21 people between 1955 and 2020, including of nine divers, eight swimmers, two fisherman, one shipwrecked person and one fallen pilot. Five of these attacks were fatal.[26]

In Egypt in 2010, one oceanic whitetip was implicated in several bites on tourists in the Red Sea near Sharm El Sheikh, resulting in one death and four injuries to humans. Accumulating evidence revealed this shark to have been conditioned to being hand fed.[27][28] In October 2019, an oceanic whitetip shark brutally attacked a female snorkeler off Mo'orea, French Polynesia. The person survived, and based on eyewitness reports and examinations of the bites, the shark may have been acting predatory.[26]

Captivity

The oceanic whitetip has fared better in captivity than other large sharks of the open ocean. Among five recorded captive oceanic whitetips, the three with time records all lived for more than a year in captivity. One of these, a female in Monterey Bay Aquarium's Outer-Bay exhibit, lived for more than three years before dying in 2003, during which it grew 0.3 m (1 ft).[29][30] The two remaining lack a time record, but grew about 0.5 m (1.6 ft) during their time in captivity.[29]

Conservation status

Oceanic whitetip with a rusty fish hook in its mouth

As of 2019, the IUCN Red List list the oceanic whitetip shark as critically endangered, as their numbers appear to have decreased in every ocean region they inhabit. While their total global population is unknown, they are estimated to have declined by around 98 percent "with the highest probability of >80% reduction over three generation lengths (61.2 years).".[1]

In 1969, Lineaweaver and Backus wrote of the oceanic whitetip: "[it is] extraordinarily abundant, perhaps the most abundant large animal, large being over 100 pounds [45 kg], on the face of the earth".[31] A study focusing on the northwest Atlantic and Gulf of Mexico, using a mix of data from US pelagic longline surveys from the mid-1950s and observations from the late 1990s, estimated a decline in numbers in this location of 99.3% over this period.[8] However, changes in fishing practices and data collection methods complicate estimates.[32] According to a January 2021 study in Nature which studied 31 species of sharks and rays, the number of these species found in open oceans had dropped by 71 per cent in around 50 years. The oceanic whitetip was included in the study.[33][34]

Oceanic whitetip sharks are mainly threatened by fisheries, sometimes intentional but usually bycatch. They are victims of longlines, hook-lines, gillnets and trawls. The sharks are used for their fins and meat.[1][6] It is eaten fresh, smoked, dried, and salted and its skin made into leather.[6] Bycatching of oceanic whitetip sharks may be reduced by removing hooks from longliners when they are in shallow water.[35] Sharks may also be threatened by pollution. Those in the northwest Atlantic have been found to accumulate high amounts of mercury.[36]

In March 2013, the oceanic whitetip was added to Appendix II of CITES meaning the species (including parts and derivatives) require CITES permits for international trade.[37] On 30 January 2018, NOAA Fisheries published a final rule to list the oceanic whitetip shark as a threatened species under the United States Endangered Species Act (ESA) (83 FR 4153).[38] From 3 January 2013, the shark was fully protected in New Zealand territorial waters under the Wildlife Act 1953.[39][40] The New Zealand Department of Conservation has classified the oceanic whitetip shark as "Migrant" with the qualifier "Secure Overseas" under the New Zealand Threat Classification System.[41]

See also

References

  1. ^ a b c Rigby, C.L.; Barreto, R.; Carlson, J.; Fernando, D.; Fordham, S.; Francis, M.P.; Herman, K.; Jabado, R.W.; Liu, K.M.; Marshall, A.; Pacoureau, N.; Romanov, E.; Sherley, R.B.; Winker, H. (2019). "Carcharhinus longimanus". IUCN Red List of Threatened Species. 2019: e.T39374A2911619. doi:10.2305/IUCN.UK.2019-3.RLTS.T39374A2911619.en. Retrieved 19 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ a b c d e Froese, Rainer; Pauly, Daniel (eds.). "Carcharhinus longimanus". FishBase. February 2013 version.
  4. ^ "Carcharhinus longimanus (Poey, 1861)". Integrated Taxonomic Information System. Retrieved 18 August 2008.
  5. ^ a b c d e f g h i Bester, Cathleen. "Oceanic Whitetip Shark". Florida Museum of Natural history. Archived from the original on 15 December 2012. Retrieved 22 July 2006.
  6. ^ a b c d e f g h i j k Compagno, Leonard J. V. (1984). Sharks of the World: An annotated and illustrated catalogue of shark species known to date. Vol. 4, Part 2. Carcharhiniformes. Food and Agriculture Organization of the United Nations. pp. 484–86, 555–61, 588. ISBN 978-92-5-101383-0. Archived from the original on 2013-08-22. Retrieved 2012-09-24.
  7. ^ a b c Bonfil, Ramón; Nakano, Hideki (2008). "The Biology and Ecology of the Oceanic Whitetip Shark, Carcharhinus Longimanus". In Camhi, Merry D.; Pikitch, Ellen K.; Babcock, Elizabeth A. (eds.). The Biology and Ecology of the Oceanic Whitetip Shark, Carcharhinus Longimanus. Blackwell Publishing Ltd. pp. 128–139. ISBN 9780632059959.
  8. ^ a b Baum, J.K. & Myers, R.A. (2004). "Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico" (PDF). Ecology Letters. 7 (3): 135–45. doi:10.1111/j.1461-0248.2003.00564.x. Archived from the original (PDF) on 2012-02-16.
  9. ^ a b "Marine Life News". British Marine Life Study Society. Summer 2004. Archived from the original on 9 June 2017. Retrieved 3 September 2017.
  10. ^ Mikael Lundvall. "Fish Watcher Record". Fishwatcher. Archived from the original on 8 December 2005. Retrieved 6 February 2006.
  11. ^ "Consideration of Proposals for Amendment of Appendices I and II (CoP15 Prop. 16)" (PDF). Convention on International Trade in Endangered Species (CITES). March 2010. Archived from the original (PDF) on 2013-05-12.
  12. ^ Andrzejaczek, S; Gleiss, A. C.; Jordan, L. K. B.; Pattiaratchi, C. B.; Howey, L. A.; Brooks, E. J.; Meekan, M. G. (2018). "Temperature and the vertical movements of oceanic whitetip sharks, Carcharhinus longimanus". Scientific Reports. 8 (1): 8351. doi:10.1038/s41598-018-26485-3.
  13. ^ Papastamatiou, Y. P.; Iosilevskii, G; Leos-Barajas, V; Brooks, E. J.; Howey, L. A.; Chapman, D. D.; Watanabe, Y. Y. (2018). "Optimal swimming strategies and behavioral plasticity of oceanic whitetip sharks". Scientific Reports. 8 (1): 551. doi:10.1038/s41598-017-18608-z.
  14. ^ a b Madigan, D. J.; Brooks, E. J.; Bond, M. E.; Gelsleichter, J; Howey, L. A.; Abercrombie, D. L.; Brooks, A; Chapman, D. D. (2015). "Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank". Marine Ecology Progress Series. 529: 185–197. doi:10.3354/meps11302.
  15. ^ "This shark fought off a deep-sea squid, first-ever picture reveals". Animals. June 5, 2020. Archived from the original on February 28, 2021. Retrieved October 19, 2021.
  16. ^ Marx R.F. (1990). The History of Underwater Exploration. Courier Dover Publications. p. 3. ISBN 978-0-486-26487-5. Archived from the original on 2014-06-30. Retrieved 2016-07-15.
  17. ^ a b c Seki, T; Taniuchi, T; Nakano, H; Shimizu, M (1998). "Age, Growth and Reproduction of the Oceanic Whitetip Shark from the Pacific Ocean". Fisheries Science. 64 (1): 14–20. doi:10.2331/fishsci.64.14.
  18. ^ Lessa, R; Santana, F. M.; Paglerani, R (1999). "Age, growth and stock structure of the oceanic whitetip shark, Carcharhinus longimanus, from the southwestern equatorial Atlantic". Fisheries Research. 42 (1–2): 21–30. doi:10.1016/S0165-7836(99)00045-4.
  19. ^ dos Santos Tambourgi, M. R.; Hazin, F; Oliveira, P. G. V.; Coelho, R; Burgess, G. H.; Roque, P (2013). "Reproductive aspects of the oceanic whitetip shark, Carcharhinus longimanus (Elasmobranchii: Carcharhinidae), in the equatorial and southwestern Atlantic Ocean". Brazilian Journal of Oceanography. 61 (2): 161–168. doi:10.1590/S1679-87592013000200008.
  20. ^ Cousteau, Jacques-Yves & Cousteau, Philippe (1970). The Shark: Splendid Savage of the Sea. Doubleday & Company, Inc.
  21. ^ "Hemingway's Sharks". Sea History for Kids. NATIONAL MARITIME HISTORICAL SOCIETY. Retrieved 9 December 2022.
  22. ^ Stanton, Doug (2003). In Harm's Way: The Sinking of the USS Indianapolis and the Extraordinary Story of Its Survivors (1st Owl Books ed.). New York: H. Holt. ISBN 978-0-8050-7366-9.
  23. ^ Martin, R. Aidan. "Elasmo Research". ReefQuest. Archived from the original on 6 February 2006. Retrieved 6 February 2006.
  24. ^ Helm, Thomas (1969). Shark! Unpredictable Killer of the Sea (6 ed.). Collier Books.
  25. ^ Bass, A.J.; D'Aubrey, J.D.; Kistnasamy, N. (1973). Sharks of the east coast of southern Africa. 1. The genus Carcharhinus (Carcharhinidae) (PDF). Durban: Oceanographic Research Institute. pp. 49–55. ISBN 0869890085. Archived from the original (PDF) on 6 September 2013.
  26. ^ a b Clua, E. C. G.; Demarchi, S; Meyer, C. G. (2021). "Suspected predatory bites on a snorkeler by an oceanic whitetip shark Carcharhinus longimanus off Moorea island (French Polynesia)". Journal of Forenic Sciences. 66 (6): 2493–2498. doi:10.1111/1556-4029.14865.
  27. ^ Egypt: German tourist killed in fourth Sharm el-Sheikh shark attack in a week Archived 2018-07-15 at the Wayback Machine. telegraph.co.uk (5 December 2010)
  28. ^ US Experts Head to Egypt to Probe Shark Attacks Archived 2016-11-10 at the Wayback Machine. CBS News (7 December 2010)
  29. ^ a b "Oceanic Whitetip Shark Carcharhinus longimanus (Poey, 1861) in Captivity". H. F. Mollet. Archived from the original on 15 May 2014. Retrieved 15 May 2014.
  30. ^ "Monterey aquarium whitetip shark dies after three years". Napa Valley Register. Archived from the original on 2020-07-10. Retrieved 2020-07-10.
  31. ^ Lineaweaver, Thomas H. III & Backus, Richard H. (1969). The Natural History of Sharks. Lippincott.
  32. ^ Baum, J.K.; Kehler, D. & Myers, R.A. (2005). "Robust estimates of decline for pelagic shark populations in the northwest Atlantic and Gulf of Mexico". Fisheries. 30: 27–30. CiteSeerX 10.1.1.417.3687.
  33. ^ Briggs, Helen (28 January 2021). "Extinction: 'Time is running out' to save sharks and rays". BBC News. Archived from the original on 28 January 2021. Retrieved 29 January 2021.
  34. ^ Richardson, Holly (27 January 2021). "Shark, ray populations have declined by 'alarming' 70 per cent since 1970s, study finds". ABC News. Australian Broadcasting Corporation. Archived from the original on 29 January 2021. Retrieved 29 January 2021.
  35. ^ Tolotti, M. T.; Bach, P; Hazin, F; Travassos, P; Dagorn, L (2015). "Vulnerability of the oceanic whitetip shark to pelagic longline fisheries". PLOS ONE. 10 (10): e0141396. doi:10.1371/journal.pone.0141396.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  36. ^ Gelsleichter, J; Sparkman, G; Howey, L. A.; Brooks, E. J.; Shipley, O. N. (2020). "Elevated accumulation of the toxic metal mercury in the Critically Endangered oceanic whitetip shark Carcharhinus longimanus from the northwestern Atlantic Ocean". Endangered Species Research. 43: 267–279. doi:10.3354/esr01068.
  37. ^ MCGrath, Matt (11 March 2013). "'Historic' day for shark protection". BBC News. Archived from the original on 10 June 2013. Retrieved 27 July 2013.
  38. ^ "Home page of NOAA Fisheries Service – Pacific Islands Regional Office". Archived from the original on 2018-06-22. Retrieved 2018-06-21.
  39. ^ "Endangered whitetip sharks to be protected". New Zealand Government. 27 September 2012. Archived from the original on 15 September 2016. Retrieved 27 September 2012.
  40. ^ "Wildlife (Oceanic Whitetip Shark) Order 2012". New Zealand government gazette. 6 December 2012. Archived from the original on 5 February 2015. Retrieved 4 February 2015.
  41. ^ Duffy, Clinton A. J.; Francis, Malcolm; Dunn, M. R.; Finucci, Brit; Ford, Richard; Hitchmough, Rod; Rolfe, Jeremy (2018). Conservation status of New Zealand chondrichthyans (chimaeras, sharks and rays), 2016 (PDF). Wellington, New Zealand: Department of Conservation. p. 9. ISBN 9781988514628. OCLC 1042901090. Archived (PDF) from the original on 2019-01-28. Retrieved 2019-01-17.