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Shortfin mako shark

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Shortfin mako shark
Scientific classification
Kingdom:
Animalia
Class:
Chondrichthyes
Order:
Lamniformes
Family:
Lamnidae
Genus:
Isurus
Species:
I. oxyrinchus
Binomial name
Isurus oxyrinchus

The shortfin mako shark, Isurus oxyrinchus ("sharp nose"), is a large mackerel shark. Along with the closely related longfin mako (Isurus paucus) it is commonly referred to as a "mako shark".

Etymology

In 1809, Constantine Rafinesque first described shortfin mako and coined the name Isurus oxyrinchus (Isurus means "the same tail", oxyrinchus means "pointy snout"). "Mako" comes from the Māori language,[2] meaning either the shark or a shark tooth. It may have originated in a dialectal variation as it is similar to the common words for shark in a number of Polynesian languages—makō in the Kāi Tahu Māori dialect,[3] mangō in other Māori dialects,[3] "mago" in Samoan, ma'o in Tahitian, and mano in Hawaiian. The first written usage is in Lee & Kendall's Grammar and vocabulary of the language of New Zealand (1820), which simply states "Máko; A certain fish".[4][5] Richard Taylor's A leaf from the natural history of New Zealand (1848) is more elaborate: "Mako, the shark which has the tooth so highly prized by the Maoris".[6]

Ecology

Range and habitat

The shortfin mako inhabits offshore temperate and tropical seas worldwide. The closely related longfin mako shark, Isurus paucus, is found in the Gulf Stream or warmer offshore waters.

It is a pelagic species that can be found from the surface down to depths of 150 m (490 ft), normally far from land though occasionally closer to shore, around islands or inlets.[7] One of only four known endothermic sharks, it is seldom found in waters colder than 16 °C (61 °F).[8]

In the western Atlantic it can be found from Argentina and the Gulf of Mexico to Browns Bank off of Nova Scotia. In Canadian waters these sharks are neither abundant nor rare. Swordfish are a good indication of shortfin makos as the former is a source of food and prefers similar environmental conditions.[9]

Shortfin makos travel long distances to seek prey or mates. In December 1998, a female tagged off California was captured in the central Pacific by a Japanese research vessel, meaning this fish traveled over 1,725 miles (2,776 km). Another swam 1,322 miles (2,128 km) in 37 days, averaging 36 miles (58 km) a day.[10]

Feeding

The head of a mako shark.

The shortfin mako feeds mainly upon cephalopods, bony fishes including mackerels, tunas, bonitos, and swordfish, but it may also eat other sharks, porpoises, sea turtles, and seabirds. They hunt by lunging vertically up and tearing off chunks of their preys' flanks and fins. Makos swim below their prey, so they can see what is above and have a high probability of reaching prey before it notices. Biting the caudal peduncle can immobilize the prey. In Ganzirri and Isola Lipari, Sicily, shortfin makos have been found with amputated swordfish bills impaled into their head and gills, suggesting that swordfish seriously injure and likely kill makos. In addition, this location, and the late spring and early summer timing, corresponding to the swordfish's spawning cycle, suggests that these makos hunt while the swordfish are most vulnerable, typical of many predators.[7]

Shortfin consume 3% of its weight each day and takes about 1.5–2 days to digest an average-sized meal. By comparison, an inactive species such as the sandbar shark consumes 0.6% of its weight a day and takes 3 to 4 days to digest it. An analysis of the stomach contents of 399 male and female mako sharks ranging from 67–328 centimetres (26–129 in) suggest makos from Cape Hatteras to the Grand Banks prefer bluefish, constituting 77.5% of the diet by volume. The average capacity of the stomach was 10% of the total weight. Shortfin makos consumed 4.3% to 14.5% of the available bluefish between Cape Hatteras and Georges Bank.[11]

Shortfin over 3 metres (9.8 ft) have interior teeth considerably wider and flatter than smaller makos, which enables them to prey effectively upon dolphins, swordfish, and other sharks.[10] An amateur videotape, taken in Pacific waters, shows a moribund spotted dolphin whose tail was almost completely severed, with a very large shortfin mako circling the dying dolphin. Makos also have the tendency to scavenge long-lined and netted fish.[12]

Jaw

Its endothermic constitution partly accounts for its relatively great speed.[13]

Like other lamnid sharks, the shortfin mako has a heat exchange circulatory system that allows the shark to be 7-10°F (4-7°C) warmer than the surrounding water. This system enables makos to maintain a stable, very high level of activity,[14] giving it an advantage over its cold-blooded prey.[15]

Behavior

The shortfin mako's speed has been recorded at 50 kilometres per hour (31 mph) with bursts of up to 74 kilometres per hour (46 mph).[16] They can leap approximate 9 metres (30 ft) high or higher in the air. Some scientists suggest that the shortfin mako can swim up to 100 kilometres per hour (62 mph), though scientists are still in debate over exactly how fast the shortfin mako shark can swim. This high-leaping fish is a highly sought-after game fish worldwide. There are cases when an angry mako jumped into a boat after having been hooked.[17]

This shark is highly migratory.[citation needed]

Life history

Reproduction

The shortfin mako shark is a yolk-sac ovoviviparous shark, giving birth to live young. Developing embryos feed on unfertilized eggs in uterus during the 15 to 18 month gestation period. This is called (oophagy) (i.e. egg-eating). Shortfins do not engage in sibling cannibalism unlike the sand tiger shark (Carcharias taurus). The 4 to 18 surviving young are born live in the late winter and early spring at a length of about 70 centimetres (28 in). It is believed that females may rest for 18 months after birth before mating again. Last and Stevens (2009) report shortfin makos bear young on average every 3 years.[18]

Lifespan

A landmark study by Natanson et al. (2006) has overturned previous highly inaccurate estimations of lifespan and sexual maturity in shortfin makos from the North Atlantic.[19] Natanson et al. (2006) aged vertebrae of 258 specimens and recorded:

  • Maximum age of 29 years in males (260 cm FL)
  • Maximum age of 32 years in females (335 cm FL)
  • 50% sexual maturity at 8 years in males (185 cm FL)
  • 50% sexual maturity at 18 years in females (275 cm FL)

Last and Stevens (2009) report similar findings.[18]

Relation to humans

Sustainable consumption

In 2010, Greenpeace International added the shortfin mako shark (Isurus oxyrinchus or mackerel shark) to its seafood red list, "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."[20]

In 2010, the Convention on Migratory Species (CMS) also added the shortfin mako shark to Annex I of its Migratory Sharks MoU. This Memorandum of Understanding, currently in effect, serves to increase international understanding and coordination for the protection of certain migratory sharks[21].

Captivity

Of all recorded attempts to keep pelagic shark species in captivity, the shortfin mako has fared the poorest; even more so than the oceanic whitetip shark, the blue shark and the great white shark. The current record is held by a specimen that, in 2001, was kept at the New Jersey Aquarium for only five days. Like past attempts at keeping Isurus in captivity, the animal appeared strong upon arrival but had trouble negotiating the walls of the aquarium, refused to feed, quickly weakened and died.[22]

Attacks on humans

ISAF statistics records forty-two shortfin attacks on humans between 1980 and 2010, three of which were fatal, along with twenty boat attacks.[23] Sharks can be attracted to spear fishermen carrying a stuck fish, and may slap them with cavitation bubbles from a swift tail flick. Generally these species of sharks will not attack humans; when humans are attacked, it is thought to be because they are mistaken for weakened or hurt prey.

See also

  • For a topical guide, see Outline of sharks.

Notes

  1. ^ "More oceanic sharks added to the IUCN Red List" (Press release). IUCN. 2007-02-22. Retrieved 2007-02-25. The global threat status was heightened for shortfin mako, a favorite shark among commercial and recreational fishermen, from Near Threatened in 2000 to Vulnerable today.
  2. ^ "Maori language - a glossary of useful words from the language of the Maori New Zealand". Retrieved 2006-08-11.
  3. ^ a b H.W.Williams (1971). Dictionary of the Maori Language (7th ed.).
  4. ^ Oxford: The Dictionary of New Zealand English: New Zealand words and their origins. 1997.
  5. ^ "Online Etymology Dictionary". Retrieved 2008-03-08.
  6. ^ Richard Taylor (1848). A leaf from the natural history of New Zealand. xiii. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)
  7. ^ a b "The Shark Gallery - Shortfin Mako Shark (Isurus oxyrinchus)". "The Shark Trust". Retrieved 2008-10-02.
  8. ^ "Shortfin Mako (Isurus oxyrinchus)". Shark Foundation / Hai-Stiftung. 05/08/29. Retrieved 2008-11-18. {{cite news}}: Check date values in: |date= (help)
  9. ^ Campana, Steven (2 October 2008). "Shortfin Mako". The Canadian Shark Research Laboratory. Retrieved 2008-11-16. {{cite news}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  10. ^ a b R. Aidan., Martin (2003). "Open Ocean: the Blue DesertShortfin Mako". ReefQuest Centre for Shark Research. Retrieved 2008-11-14. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  11. ^ Stillwell, C.E.; Kohler, N.E. (1982). "Food, Feeding Habits, and Estimates of Daily Ration of the Shortfin Mako (Isurus oxyrinchus ) in the Northwest Atlantic". Canadian Journal of Fisheries and Aquatic Sciences. 39 (3): 407–414. doi:10.1139/f82-058. Retrieved 2008-11-04. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  12. ^ Fergusson, Ian. "Shortfin Mako Shark (Isurus oxyrinchus)". Retrieved 2008-11-18. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  13. ^ Passarelli, Nancy. "SHORTFIN MAKO". Florida Museum of Natural History. Retrieved 2008-10-06. {{cite news}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  14. ^ "Shortfin Mako". Australian Museum. May 2007. Retrieved 2008-11-15. {{cite news}}: |first= missing |last= (help)
  15. ^ "Shortfin Mako Shark". 2008 Discovery Communications, LLC. Tuesday, October 30, 2007. Retrieved 2008-11-04. {{cite news}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)
  16. ^ R. Aidan Martin. "Biology of the Shortfin Mako". ReefQuest Centre for Shark Research. Retrieved 2006-08-12.
  17. ^ Grimble, Sir Arthur (1952). "A Pattern of Islands; Ch. 5 Lagoon Days". Early New Zealand Books (NZETC). Retrieved 16 Oct. 2011. {{cite web}}: Check date values in: |accessdate= (help)
  18. ^ a b Last, PR (2009). Sharks and Rays of Australia — Second Edition. Australia: CSIRO (Commonwealth Scientific and Industrial Research Organisation). ISBN 978-0-643-09457-4. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  19. ^ Natanson, L.J. (2006). "Validated age and growth estimates for the shortfin mako, Isurus oxyrhinchus, in the North Atlantic Ocean" (PDF). Environmental Biology of Fishes. 77 (3–4): 367–383. doi:10.1007/s10641-006-9127-z. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ Greenpeace International Seafood Red list
  21. ^ http://www.cms.int/species/sharks/MoU/Migratory_Shark_MoU_Eng.pdf
  22. ^ Elasmobranch Research around Monterey Bay
  23. ^ ISAF Statistics on Attacking Species of Shark

References

Wikispecies has information related to Isurus oxyrinchus.

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