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Overview

Brief Summary

Biology

Blue sharks are viviparous, giving birth to live young after a gestation period of nine to twelve months (6) (7). Up to 135 pups can be born per litter, partially depending on the size of the female, but the average is 25 to 50 (5) (6). Maturity is reached at approximately five to six years old and blue sharks are known to have lived to 20 years (7). Although often observed cruising slowly and sluggishly the blue shark is capable of rapid movement if it is excited or feeding (6). This species will often circle its prey before moving in to attack it. Blue sharks primarily feed upon relatively small prey, such as bony fish and squid, but will also take larger prey including mammalian carrion (1).
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Description

The blue shark is easily identified by its beautifully coloured slender body, which is a deep indigo-blue across the back, shading to a vibrant blue on the sides, and paling to white underneath (4). This shark has large eyes, triangular teeth, a conical snout, long pectoral fins and a second dorsal fin much smaller than the first (2) (4). While its elongated caudal fin provides swimming power, its sleek, tapered body makes it a graceful mover (5).
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Comprehensive Description

Description

  Common names: shark (English), tiburón (Espanol)
 
Prionace glauca (Linnaeus, 1758)

Blue shark



Very elongate and fusiform; snout long and narrowly rounded; no spiracles; eyes round, with nictitating membrane; teeth serrated, long and triangular, broader and curved on top jaw, center tooth of top jaw very large; 5 short gill slits, last 2 over pectoral base; 1st  dorsal fin low, its origin well behind pectoral fins; no ridge between dorsals; pectorals very long, narrow, slightly curved, pointed tips; tail base with small keel; tail asymmetric, well developed lower lobe, upper lobe notched under tip.


Back dark blue, flanks intense blue; belly white; tip of pectoral and anal dark.

Size: 380 cm.

Habitat: oceanic, epipelagic.

Depth: 0-350 m.

Southern California to the lower 2/3 of the Gulf of California and to Peru, and probably all the oceanic islands.   
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Biology

Oceanic, but may be found close inshore where the continental shelf is narrow (Ref. 6871, 58302). Usually found to at least 150 m (Ref. 26938). Reported from estuaries (Ref. 26340). Epipelagic, occasionally occurs in littoral areas (Ref. 58302). Feeds on fishes (herring, silver hake, white hake, red hake, cod, haddock, pollock, mackerel, butterfish, sea raven and flounders (Ref. 5951)), small sharks, squids, pelagic red crabs, cetacean carrion, occasional sea birds and garbage (Ref. 5578). Viviparous (Ref. 50449). Sexual dimorphism occurs in skin thickness of maturing and adult females (Ref. 49562). May travel considerable distances (one specimen tagged in New Zealand was recaptured 1,200 km off the coast of Chile) (Ref. 26346). Potentially dangerous to humans (Ref. 6871, 13513). Marketed fresh, dried or salted, and frozen; meat utilized for consumption, hides for leather and fins for soup (Ref. 9987). Sexually mature at 250 cm long and 4-5 years old. The female gives birth up to 80 young measuring 40 cm long, gestation lasts almost a year (Ref. 35388). Produces from 4 to 135 young a litter (Ref. 26938).
  • Compagno, L.J.V. 1984 FAO Species Catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 2 - Carcharhiniformes. FAO Fish. Synop. 125(4/2):251-655. Rome: FAO. (Ref. 244)
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Description

 Blue sharks can grow up to 3.8 m long and are easily distinguished by their bright blue dorsal coloration and white underside. Generally, blue sharks have a slender body, long conical snout, long and narrow pectoral fins and a caudal fin with a long upper lobe.The blue shark is often seen cruising slowly at the surface, with its large pectoral fins outspread, and its first dorsal fin and terminal caudal lobe out of the water. It is a viviparous species and the number of young varies from 4 to 135 per litter, with a size at birth around 40 cm. The gestation period is from 9 to 12 months, and possible maximum longevity is around 20 years. Males mature around 180 to 200 cm and females around 220 cm in length.  

The blue shark feeds on relatively small prey, especially squid and bony fishes, though other invertebrates, small sharks, and mammalian carrion is readily taken and seabirds occasionally are caught at the surface of the water. Squid are a very important prey of the blue shark and some species form huge breeding aggregations, which are attended by blue sharks. Much of the prey of the blue shark is pelagic, though bottom fishes and invertebrates figure in its diet also.

 This common oceanic shark is usually caught with pelagic longlines but also pelagic trawls, and even bottom trawls near coasts.
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Distribution

Blue sharks are one of the most wide ranging shark species and can be found in all major oceans (except the Arctic), as well as the Mediterranean Sea and in temperate and tropical pelagic waters.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )

Other Geographic Terms: cosmopolitan

  • Last, P., J. Stevens. 1994. Sharks and Rays of Australia. Melbourne, Australia: CSIRO PUBLISHING.
  • Megalofonou, P., D. Damalas, G. De Metrio. 2009. Biological characteristics of blue shark, Prionace glauca, in the Mediterranean Sea. Journal of the Marine Biological Association of the United Kingdom, 89/6: 1233-1242.
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Range Description

The Blue Shark is one of the most wide ranging of all sharks, being found throughout tropical and temperate seas from latitudes of about 60°N'50°S. It is oceanic and pelagic, found from the surface to about 350 m depth; occasionally it occurs close inshore where the continental shelf is narrow. The Blue Shark prefers temperatures of 12'20°C and is found at greater depths in tropical waters (Last and Stevens 1994).
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Newfoundland to Argentina
  • North-West Atlantic Ocean species (NWARMS)
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Zoogeography

See Map (including site records) of Distribution in the Tropical Eastern Pacific 
 
Global Endemism: All species, TEP non-endemic, Circumtropical ( Indian + Pacific + Atlantic Oceans), "Transpacific" (East + Central &/or West Pacific), All Pacific (West + Central + East), East Pacific + Atlantic (East +/or West), Transisthmian (East Pacific + Atlantic of Central America), East Pacific + all Atlantic (East+West)

Regional Endemism: All species, Eastern Pacific non-endemic, Tropical Eastern Pacific (TEP) non-endemic, Continent + Island (s), Continent, Island (s)

Residency: Resident

Climate Zone: North Temperate (Californian Province &/or Northern Gulf of California), Northern Subtropical (Cortez Province + Sinaloan Gap), Northern Tropical (Mexican Province to Nicaragua + Revillagigedos), Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo), South Temperate (Peruvian Province )
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Circumglobal in temperate and tropical waters. Western Atlantic: Newfoundland, Canada to Argentina. Central Atlantic. Eastern Atlantic: Norway to South Africa, including the Mediterranean. Indo-West Pacific: East Africa to Indonesia, Japan, Australia, New Caledonia, and New Zealand. Eastern Pacific: Gulf of Alaska to Chile. Probably the widest ranging chondrichthyian. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139).
  • Compagno, L.J.V. 1984 FAO Species Catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 2 - Carcharhiniformes. FAO Fish. Synop. 125(4/2):251-655. Rome: FAO. (Ref. 244)
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Circumglobal in tropical through temperate seas (including Mediterranean Sea, western Baltic Sea, North Sea, Seychelles, Madagascar, Mascarenes, Hawaiian Islands).
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Cosmopolitan on the high seas in the warmer parts of all the oceans. Including in the western Atlantic: outer Nova Scotia and the banks of Newfoundland; in the eastern Atlantic: England and Scotland with some found at the Orkneys and southern Norway; Mediterranean.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Compagno, L.J.V., 1984; Claro, R., 1994; Muus, B.J. and J.G. Nielsen, 1999; Smith, C.L., 1997; Whiteheat, P.J.P., M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese, 1984.
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Depth

Depth Range (m): 0 (S) - 350 (S)
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Range

Blue sharks are probably the most wide-ranging and (at least initially) one of the most abundant of all shark species, occurring in temperate and tropical waters from 50°N to 40°S around the globe (2). A migratory species, they periodically travel clockwise around the Atlantic, seemingly riding the Gulf Stream to Europe, taking various currents down the European and African coasts, and riding the Atlantic North Equatorial Current to the Caribbean region (1).
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Physical Description

Morphology

The striking coloration of blue sharks makes them one of the most distinctive species in the family Carcharhinidae (requiem or whaler sharks). The dorsum is a deep shade of indigo, while the flanks are a vibrant blue. The ventral surface fades to a light grey, exhibiting the typical pelagic countershaded coloration that deceives the eyes of bottom-dwelling prey or predators by blending in with light coming from the sun. The body is streamlined and thin, with an elongated heterocercal caudal (tail) fin, making it one of the fastest sharks in the ocean. The second dorsal fin is approximately half the size of the first, and the pectoral fins are proportionately longer than in most other shark species. The eyes are large, and the mouth is lined with several rows of triangular, serrated teeth; each tooth is usually replaced every 8 to 15 days. Blue sharks can reach 4 m in total length and weigh up to 240 kg.

Range mass: 240 (high) kg.

Range length: 4 (high) m.

Average length: 3.35 m.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger

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Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0
  • Compagno, L.J.V., D.A. Ebert and M.J. Smale 1989 Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p. (Ref. 5578)
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Size

Length max (cm): 380.0 (S)
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Size

Maximum size: 3850 mm TL
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Max. size

400 cm TL (male/unsexed; (Ref. 35388)); max. published weight: 205.9 kg (Ref. 40637); max. reported age: 20 years (Ref. 27347)
  • IGFA 2001 Database of IGFA angling records until 2001. IGFA, Fort Lauderdale, USA. (Ref. 40637)
  • Muus, B.J. and J.G. Nielsen 1999 Sea fish. Scandinavian Fishing Year Book, Hedehusene, Denmark. 340 p. (Ref. 35388)
  • ICES Demersal Fish Committee 1997 Report of the Study Group on Elasmobranchs. ICES CM /G:2, 123 p. (Ref. 27347)
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to 400.0cm TL; max. weight: 200 kg.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Compagno, L.J.V., 1984; Claro, R., 1994; Muus, B.J. and J.G. Nielsen, 1999; Smith, C.L., 1997; Whiteheat, P.J.P., M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese, 1984.
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Blue Shark

The heaviest Blue Shark weighed 862LB.

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Diagnostic Description

Description

Lives in the open sea, but may also be found along coastal areas. Prefers cool waters from 7-16° C but tolerates 21° C and more. In tropical offshore areas it occurs at depths of 80-220 m; in warm-temperate areas they occur close to shore and near the surface (Ref. 5485). A scavenger/ predator that feeds mainly on squid, but also on bony fishes, small sharks, pelagic crustaceans, algae, and crustaceans (Ref. 5213). Length of 650 cm is unconfirmed. Marketed fresh, dried/salted and frozen; meat utilized for consumption, hides for leather and fins for soup (Ref. 9987).
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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A slim, graceful blue shark with a long, conical snout, large eyes, and curved triangular upper teeth with saw edges; pectorals long and narrow; no interdorsal ridge (Ref. 5578). Dark blue dorsally, bright blue on the sides, white ventrally (Ref. 5578). Tips of pectoral fins and anal fin dusky (Ref. 9997).
  • Compagno, L.J.V., D.A. Ebert and M.J. Smale 1989 Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p. (Ref. 5578)
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Ecology

Habitat

Blue sharks inhabit the epipelagic and mesopelagic zones (from the surface to about 350 m in depth), in water temperatures ranging between 12 and 20°C. While they are mainly found in pelagic, open-ocean waters, they may sometimes be found closer to shore in the neritic zone, near the edge of continental shelves.

Range depth: 0 to 350 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: pelagic

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Habitat and Ecology

Habitat and Ecology
The Blue Shark reaches a maximum size of about 380 cm TL. About 50% of males in the Atlantic are sexually mature by 218 cm, although some may reach maturity as small as 182 cm. Females are sub-adult from 173-221 cm and fully mature from 221 cm (Pratt 1979), although pregnant fish as small as 183 cm have been recorded from the eastern Pacific (Williams 1977).

Blue Sharks are placentally viviparous, producing litters averaging about 35 (maximum recorded 135) after a gestation period of 9-12 months. At birth the pups are 35-50 cm long. Reproduction has been reported as seasonal in most areas, with the young often born in spring or summer (Pratt 1979, Stevens 1984a, Nakano 1994) although the periods of ovulation and parturition may be extended (Strasburg 1958, Hazin et al. 1994). The skin of females is about three times thicker than that of males to withstand the extensive courtship bites of males. Females can store sperm in their nidamental glands for extended periods, for later fertilisation (Pratt 1979). Ageing studies suggest a longevity of about 20 years with males maturing at 4-6 and females at 5-7 years (Stevens 1975, Cailliet et al. 1983b, Nakano 1994). Smith et al. (1998) estimated the intrinsic rate of population increase at MSY to be 0.061.

Blue Sharks are highly migratory with complex movement patterns and spatial structure related to reproduction and the distribution of prey. There tends to be a seasonal shift in population abundance to higher latitudes associated with oceanic convergence or boundary zones as these are areas of higher productivity. Tagging studies of blue sharks have demonstrated extensive movements of blue sharks in the Atlantic with numerous trans-Atlantic migrations which are probably accomplished by swimming slowly and utilising the major current systems (Stevens 1976, Casey 1985, Stevens 1990). More limited tagging in the Pacific has also shown extensive movements of up to 9,200 km (P. Saul pers. comm.). Substantial data from the North Atlantic on the distribution, movements and reproductive behaviour of different segments of the population suggest a complex reproductive cycle. This involves major oceanic migrations associated with mating areas in the north-western Atlantic and pupping areas in the north-eastern Atlantic (Pratt 1979, Casey 1985, Stevens 1990).

The diet of Blue Sharks consists mainly of small pelagic fish and cephalopods, particularly squid; however, invertebrates (mainly pelagic crustaceans), small sharks, cetaceans (possibly carrion) and seabirds are also taken (Compagno 1984b). While most of the fish prey is pelagic, bottom fishes also feature in the diet. Blue sharks are known to feed throughout the 24-hour period but have been reported to be more active at night, with highest activity in the early evening (Sciarrotta and Nelson 1977).

Systems
  • Marine
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Habitat Type: Marine

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Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
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nektonic
  • North-West Atlantic Ocean species (NWARMS)
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Prefers waters if 7-16 C, often near surface.
  • North-West Atlantic Ocean species (NWARMS)
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Environment

pelagic-oceanic; oceanodromous (Ref. 51243); marine; depth range 1 - 1000 m (Ref. 89422), usually 80 - 220 m (Ref. 55193)
  • Riede, K. 2004 Global register of migratory species - from global to regional scales. Final Report of the R&D-Projekt 808 05 081. Federal Agency for Nature Conservation, Bonn, Germany. 329 p. (Ref. 51243)
  • McMillan, P.J., M.P. Francis, G.D. James, L.J. Paul, P.J Marriott, E. Mackay, B.A. Wood, L.H. Griggs, H. Sui and F. Wei 2011 New Zealand fishes. Volume 1: A field guide to common species caught by bottom and midwater fishing. New Zealand Aquatic Environment and Biodiversity Report No. 68. 329 p. (Ref. 89422)
  • Florida Museum of Natural History 2005 Biological profiles: blue shark. Retrieved on 26 August 2005, from www.flmnh.ufl.edu/fish/Gallery/Descript/BlueShark/BlueShark.html. Ichthyology at the Florida Museum of Natural History: Education-Biological Profiles. FLMNH, University of Florida. (Ref. 55193)
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Depth range based on 12253 specimens in 1 taxon.
Water temperature and chemistry ranges based on 11381 samples.

Environmental ranges
  Depth range (m): 0 - 4700
  Temperature range (°C): 1.478 - 27.155
  Nitrate (umol/L): 0.165 - 33.615
  Salinity (PPS): 30.381 - 36.430
  Oxygen (ml/l): 0.732 - 7.210
  Phosphate (umol/l): 0.147 - 2.618
  Silicate (umol/l): 1.436 - 80.155

Graphical representation

Depth range (m): 0 - 4700

Temperature range (°C): 1.478 - 27.155

Nitrate (umol/L): 0.165 - 33.615

Salinity (PPS): 30.381 - 36.430

Oxygen (ml/l): 0.732 - 7.210

Phosphate (umol/l): 0.147 - 2.618

Silicate (umol/l): 1.436 - 80.155
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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 The blue shark is probably the widest ranging shark found in the main oceans and seas of the world, from the surface to at least 400 m depth. Blue sharks are a migratory species.
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Depth: 0 - 350m.
Recorded at 350 meters.

Habitat: pelagic. Blue shark.  (Linnaeus, 1758)  Brilliant bright blue above , white below. Vivaporous; the most fecund of all sharks with 35 -135 pups per litter; born at 50 cm; mature at 2,2 m; Attains 3,5 m.; Scavenger / predator; can be dangerous to man. The well known video footage of a shark attacking the chain clad arm of Valerie Taylor shows this shark. Widespread throughout all major oceans, favours waters with a temperature of 12-16 deg C. In tropical areas found offshore at some depth (80 - 220 m) but occurring close to shore and near surface in warm temperate areas.
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Pelagic; marine; depth range to 350 m. Oceanic, but may be found close inshore where the continental shelf is narrow. Usually found to at least 150 m.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Compagno, L.J.V., 1984; Claro, R., 1994; Muus, B.J. and J.G. Nielsen, 1999; Smith, C.L., 1997; Whiteheat, P.J.P., M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese, 1984.
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Salinity: Marine, Marine Only

Inshore/Offshore: Offshore Only, Offshore

Water Column Position: Surface, Near Surface, Mid Water, Water column only

Habitat: Water column

FishBase Habitat: Pelagic
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The blue shark is a pelagic species occurring in the open ocean near the surface, inhabiting slightly deeper, cooler waters when in tropical environments (4). Although typically an offshore species, the blue shark may venture inshore, especially at night (1).
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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
  • Riede, K. 2004 Global register of migratory species - from global to regional scales. Final Report of the R&D-Projekt 808 05 081. Federal Agency for Nature Conservation, Bonn, Germany. 329 p. (Ref. 51243)
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Trophic Strategy

Blue sharks prey on up to 24 species of cephalopods and 16 species of fish. They primarily feed upon non-active, gelatinous, mesopelagic/bathypelagic cephalopods such as blanket octopus (genus Tremoctopus), bathyscaphoid squids (family Cranchiidae), and pelagic octopus (Ocythoe tuberculata). Prey also includes small schooling fishes, such as long-snouted lancetfish (Alepisaurus feroxe), snake mackerel (Gempylus serpens), and castor oil fish (Ruvettus pretiosus). During their reproductive migration cycles off of the coast of Brazil, blue sharks were found to have consumed seabirds, including great shearwaters (Puffinus gravis).

Animal Foods: birds; fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

  • Ichii, T., T. Kubodera, H. Watanabe. 2007. Feeding habits of the Blue shark, Prionace glauca, and Salmon shark, Lamna ditropis, in the transition region of the Western North Pacific. Reviews in Fish Biology and Fisheries, 17(2): 111-123.
  • Vaske, L. 2012. Feeding habits of the Blue shark (Prionace glauca) off the coast of Brazil. Biota Neotropica, 9(3): 2. Accessed April 17, 2012 at http://www.biotaneotropica.org.br/v9n3/pt/fullpaper?bn00809032009+en.
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Found worldwide in tropical and temperate seas; a pelagic species, sometimes advancing into coastal waters (Ref. 9137). Occurs on the continental shelf (Ref. 75154). Prefer temperatures of 7-16°C; usually found in deeper waters in the tropics (Ref. 5951). A carnivore (Ref. 9137). Parasites of the species include: Hepatoxylon squali pleurocercoid, Phyllobothrium dagnallium, Phyllobothrium sp. and Platybothrium parvum (Ref. 5951).
  • Clarke, M.R. and J.D. Stevens 1974 Cephalopods, blue sharks and migration. J. Mar. Biol. Ass. U.K. 54:949-957. (Ref. 4928)
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Bony fishes, small sharks, squids, pelagic red crabs, cetacean carrion, occasional sea birds and garbage.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Compagno, L.J.V., 1984; Claro, R., 1994; Muus, B.J. and J.G. Nielsen, 1999; Smith, C.L., 1997; Whiteheat, P.J.P., M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese, 1984.
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Feeding

Feeding Group: Carnivore

Diet: octopus/squid/cuttlefish, Pelagic crustacea, bony fishes, sharks/rays, sea snakes/mammals/turtles/birds
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Associations

Blue sharks are top-level predators that help to regulate prey populations in the marine pelagic environment.

Pilotfish (Naucrates ductor) have a mutualistic symbiosis with blue sharks. They clean the shark's teeth and gills and removes any parasitic species that have attached themselves to the shark's skin. In return, pilotfish gain protection from predators and a ready source of food.

Many species of copepods are found on the gills and outer skin of blue sharks. Several tapeworm and one nematode species have been found in the stomach and spiral valve of blue sharks, resulting from consumption of infected fish that are the intermediate hosts of these parasites.

Mutualist Species:

Commensal/Parasitic Species:

  • A.C. Henderson, K., K. Flannery, J. Dunne. 2002. Parasites of the Blue shark (Prionace glauca) in the North East-Atlantic Ocean. Journal of Natural History, 36(16): 1995-2004.
  • Rokicki, J., D. Bychawska. 1991. Parasitic copepods of Carcharhinidae and Sphyridae (Elasmobranchia) from the Atlantic Ocean. Journal of Natural History, 25/6: 1439-1448.
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Aside from predation by humans for the lucrative shark fin trade, blue sharks are not frequently preyed upon. Occasional predators can include larger sharks such as shortfin makos Isurus paucus and great whites (Carcharodon carcharias), as well as killer whales Orcinus orca, while juveniles can also be taken by California sea lions (Zalophus californianus).

Due to their pelagic lifestyle, blue sharks exhibit countershading. The lighter coloration on the ventral surface helps to camouflage the sharks against the background of lighter-colored water when viewed from below. In contrast, the darker shades of blue and silver on the dorsal side allows them to blend in with the depths below when viewed from above. This countershading, along with a streamlined body shape, allows blue sharks to maneuver both swiftly and unnoticed as both predator and prey.

Known Predators:

Anti-predator Adaptations: cryptic

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Life History and Behavior

Behavior

Most sharks are known to use body language to signal aggression, but there is little data available on whether sharks utilize other forms of communication between individuals. Like all sharks, blue sharks have highly developed senses of smell, sight, and touch. The lateral line is a sensory organ running down the length of their body that detects pressure waves from movements in the water, allowing the sharks to perceive movements of prey. They also possess electroreceptors called Ampullae of Lorenzini on the underside of the snout, which detect electrical fields generated by the muscle contractions of prey items.

Communication Channels: visual

Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical ; electric

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Diet

Primarily squids and fishes, including herring, silver hake, white hake, red hake, cod, haddock, pollock, mackerel, butterfish, sea raven and flounders
  • North-West Atlantic Ocean species (NWARMS)
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Life Cycle

After fertilization, embryos develop inside the female's uterus, nourished by a placenta-like yolk sac. Females give birth to fully-developed, live young. Blue sharks have one of the fastest growth rates of all sharks, growing up to 30 cm annually until maturity. Blue sharks are 35to 50 cm in length at birth, and will grow up to 400 cm (although the average length is 335 cm). Both sexes reach adulthood at about 220 cm in length. Juveniles usually stay in pupping areas of the sub-Arctic boundary (42°N North Pacific Ocean) until they reach maturity at 5 years of age.

Development - Life Cycle: indeterminate growth

  • Camhi, M., E. Pikitch, E. Babcock. 2008. Sharks of the Open Ocean: Biology, Fisheries, & Conservation. Singapore: Blackwell Publishing.
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Distinct pairing with embrace (Ref. 205). Viviparous (Ref. 26281), placental (Ref. 50449); 4-63 young in a litter (Ref. 9997); 4-135 (usually 15-30) pups (Ref.58048), about 35-44 cm at birth. Gestation period ranges from 9 to 12 months (Ref. 244).Sexual dimorphism is evident in skin thickness of maturing and adult females (Ref. 49562). Females have thicker skin layer than males of the same size (Ref. 49562).
  • Breder, C.M. and D.E. Rosen 1966 Modes of reproduction in fishes. T.F.H. Publications, Neptune City, New Jersey. 941 p. (Ref. 205)
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Life Expectancy

Blue sharks in the wild have an average lifespan of 15 to 16 years. Blue shark life expectancy decreases to an average of 8 years when held in captivity, likely due to their inability to engage in their pelagic and migratory lifestyle.

Range lifespan

Status: wild:
20 (high) years.

Range lifespan

Status: captivity:
8 (high) years.

Average lifespan

Status: wild:
15 years.

Typical lifespan

Status: captivity:
8 (high) years.

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Lifespan, longevity, and ageing

Maximum longevity: 20 years (wild)
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Reproduction

Blue sharks congregate together on continental shelves during the summer. Mating begins when a male bites a female between her first and second dorsal fins. For this reason, the skin over most of a female's dorsum may be up to three times as thick as in males. Insemination occurs via insertion of one of the claspers into the female's urogenital opening. Pair bonding does not occur, and after mating, individuals separate.

Mating System: polygynandrous (promiscuous)

Males reach sexual maturity at 187 cm in length, while females become mature at 220 cm. It is not definitively known if females breed every year and deposited sperm may be stored within the female's oviductal gland for several months after mating. Once pregnant, females migrate north to birthing and pupping grounds in the sub-Arctic boundary. Gestation lasts from 9 to 12 months, and up to 130 pups in a litter have been documented, but 25 to 50 pups are born on average. Pups average 39 cm at birth. Unlike bony fish, sharks utilize internal fertilization. The male bites down and insert a clasper inside the female to transfer sperm. Females have thick skin to protect them from injury when the males bite them during mating. Blue sharks are viviparous.

Breeding interval: It is unknown whether female blue sharks breed annually, or less frequently.

Breeding season: In the northern Pacific, most births occur from December to April.

Range number of offspring: 25 to 130.

Range gestation period: 9 to 12 months.

Range age at sexual or reproductive maturity (female): 5 to 6 years.

Range age at sexual or reproductive maturity (male): 5 to 6 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous ; sperm-storing ; delayed fertilization

As in other viviparous species, female blue sharks provide nourishment and protection to their young as they develop. After birth, shark pups separate from their mother and have no further contact.

Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female)

  • Shark Foundation/Hai-Stiftung. 1997. "Blue Shark (Prionace Glauca)" (On-line). Shark Foundation Hai-Stiftung. Accessed April 16, 2012 at http://www.shark.ch/Database/Search/species.html?sh_id=1032.
  • Camhi, M., E. Pikitch, E. Babcock. 2008. Sharks of the Open Ocean: Biology, Fisheries, & Conservation. Singapore: Blackwell Publishing.
  • Pratt Jr., H., J. Carrier. 2001. A review of elasmobranch reproductive behavior with a case study on the nurse, Ginglymostoma cirratum. Environmental Biology of Fishes, 60: 157-188.
  • Pratt Jr., H. 1979. Reproduction of the Blue shark (Prionace glauca). Fishery Bulletin, 77: 445-470. Accessed May 25, 2012 at http://isurus.mote.org/research/trl/shark_mating/Pratt_1979.pdf.
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Viviparous with up to 80 young in a litter but usually less. Pups are 35 - 45 cm TL at birth; gestation period 9 - 12 months.
  • Bigelow, H.B. and W.C. Schroeder, 1953; Compagno, L.J.V., 1984; Claro, R., 1994; Muus, B.J. and J.G. Nielsen, 1999; Smith, C.L., 1997; Whiteheat, P.J.P., M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese, 1984.
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Egg Type: Live birth, No pelagic larva
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Prionace glauca

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 33 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

CTTTACCTAATTTTTGGTGCATGAGCAGGTATAGTTGGGACAGCCCTA---AGCCTCCTAATTCGAGCTGAACTTGGGCAACCTGGATCTCTTTTAGGAGAT---GATCAGATTTATAATGTAATTGTAACCGCCCACGCTTTTGTAATAATCTTTTTTATGGTTATACCAATCATAATTGGTGGTTTCGGAAATTGACTAGTTCCTTTAATA---ATTGGAGCACCAGATATAGCCTTCCCACGAATAAATAACATAAGCTTCTGACTTCTTCCACCATCATTTCTTCTCCTCCTCGCCTCTGCTGGAGTTGAAGCCGGAGCAGGTACTGGTTGAACAGTTTATCCTCCATTAGCTAGTAACCTAGCACATGCTGGACCATCTGTTGATTTA---GCTATTTTCTCTCTTCACTTAGCCGGTATTTCATCAATTTTAGCTTCAATTAACTTTATTACAACCATTATTAATATAAAACCACCAGCCATTTCCCAATATCAAACACCATTATTTGTTTGATCTATTCTTGTAACCACTATTCTTCTTCTCCTAGCACTTCCAGTTCTTGCAGCA---GGTATTACAATATTACTTACAGATCGTAACCTTAATACTACATTCTTTGACCCTGCAGGTGGAGGAGATCCAATCCTTTATCAGCACTTA
-- end --

Download FASTA File

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Statistics of barcoding coverage: Prionace glauca

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 35
Specimens with Barcodes: 67
Species With Barcodes: 1
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Conservation

Conservation Status

Although not usually a targeted species, blue sharks are caught as bycatch by longline and dragnet fishing fleets, and to a lesser extent by sport fishermen. International conservation projects have been implemented to decrease the harvest of pelagic sharks, including this species. In 1991, the Australian Government implemented legislation that banned Japanese longline fishing fleets from taking shark fins without their attendant carcasses. Canada issued a fishery management plan for shark species in 1995 that established catch limits of 250,000 kg for blue sharks, and implemented limitations on finning and gear use, licenses, areas and seasons, and bycatch limits. Management plans have been in place in the US since 1993. Proper licensing and commercial quota limits have been introduced, and finning has also been banned within the US Exclusive Economic Zone. However, exploitation by the shark finning industry has still decreased populations globally, and the IUCN lists this species as "Near Threatened".

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: near threatened

  • Campana, S., W. Joyce, M. Manning. 2009. Bycatch and discard mortality in commercially caught blue sharks Prionace glauca assessed using archival satellite pop-up tags. Marine Ecology Progress Series, 387: 241-253.
  • Stevens, J. 2009. "Blue Shark" (On-line). IUCN Red List of Threatened Species. Accessed April 23, 2012 at http://www.iucnredlist.org/apps/redlist/details/39381/0.
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IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2009

Assessor/s
Stevens, J.

Reviewer/s
Musick, J.A. & Fowler, S.L. (Shark Red List Authority)

Contributor/s

Justification
This assessment is based on the information published in the 2005 shark status survey (Fowler et al. 2005).

This abundant pelagic and oceanic shark is widespread in temperate and tropical waters. It is relatively fast-growing and fecund, maturing in 4–6 years and producing average litters of 35 pups. The Blue Shark (Prionace glauca) is taken in large numbers (an estimated 20 million individuals annually), mainly as bycatch, but there are no population estimates and many catches are unreported. The few fishery assessments carried out suggest relatively little population decline. There is concern over the removal of such large numbers of this likely keystone predator from the oceanic ecosystem.
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N4 - Apparently Secure

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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IUCN Red List: Listed, Near threatened

CITES: Not listed
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Status

Classified as Lower Risk / Near Threatened (LR/nt) on the IUCN Red List (1).
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Population

Population Trend
Unknown
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Threats

Major Threats
Blue Sharks are rarely target commercial species but are a major bycatch of longline and driftnet fisheries, particularly from nations with high-seas fleets. Much of this bycatch is often unrecorded. Blue sharks are also taken by sport fishermen, particularly in the United States, Europe and Australia.

Periodically, small target fisheries have existed for Blue Sharks such as a seasonal longline fishery for juveniles of 50-150 cm near Vigo, Spain. Some 3t of gutted individuals were observed over a two-day period at Vigo fish market (A. Kingman pers. comm.). A Taiwanese (POC) longline fishery in Indonesian waters took about 13,000 t live weight of blue sharks in 1993 (N. Bentley pers. comm.).

Blue Shark catch rates reported from commercial longlining in the Atlantic Ocean range in average values from 2.9-100 (Stevens and Wayte 1999), while average catch rates as high as 145.0 have been recorded from research longlining (A. da Silva pers. comm.). Stevens (in press) estimated a catch of 137,800 t of Blue Shark from high-seas longline fleets, and 2,300 t from high-seas purse¬seining, in the Pacific in 1994. Bonfil (1994) calculated that 21,152 t of Blue Shark were taken by high-seas driftnet fleets in the Pacific during the 1989-90 period. The annual global catch of blue sharks is likely to be around 20 million individuals.

The limited fishery assessments carried out to date have shown no evidence of a declining trend in catch rates of Blue Sharks with time in the Atlantic or Indian Oceans. However, a 20% decrease was evident in the North Pacific between the periods 1971-1982 to 1983-1993 (Nakano 1996). No consistent decline in catch rates through the fishing season was evident for Japanese longliners fishing in Australian waters (Stevens and Wayte 1999).
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Near Threatened (NT)
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
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Although blue sharks are among the most abundant, widespread, fecund and faster growing of the sharks, they are one of the most heavily fished sharks in the world. With an estimated 10 to 20 million individuals caught and killed each year, there is concern not only about what this is doing to blue shark populations, but also about the effect the removal of such an important predator might be having on the oceanic ecosystem (1). Blue sharks are one of the most important species in the international shark fin trade. However, their meat, while eaten in a few countries, is not very popular (8). They are also an important angling species in some areas (1).
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Management

Conservation Actions

Conservation Actions
The 1995 Fisheries Management Plan for pelagic sharks in Atlantic Canada established precautionary catch levels of 250 t for Blue Shark in the target shark fishery. License limitation, a ban on finning, restrictions on gear, area and seasons, bycatch limits and restrictions to recreational fishers permitting hook-and-release only were also implemented (Hurley 1998).

In 1991, Australia brought in legislation that prevented Japanese longliners fishing in the EEZ from landing shark fins unless they were accompanied by the carcass.

Since 1993, shark fisheries in Atlantic and Gulf of Mexico waters in the US have been managed under the Fishery Management Plan for Sharks of the Atlantic Ocean. The plan set commercial quotas for 10 species of pelagic sharks at 580t dressed weight annually, with recreational bag limits also applied. Commercial fishers require an annual shark permit, and finning is prohibited. In Mexico, a high-seas longline fishery taking pelagic sharks was banned within the EEZ in 1990 (Holts et al. 1998).
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Conservation

International obligations that regulate the fishing of sharks include the Code of Conduct for Responsible Fishing of the Food and Agriculture Organisation (FAO) of the United Nations, the International Plan of Action for Sharks (IPOA-SHARKS), the United Nations' Agreement on Straddling Stocks and Highly Migratory Species, and the Sustainable Fisheries Act. Although some countries have banned finning, there are no binding international treaties for the management of sharks, including the regulation or outlawing of finning (9). The blue shark is listed on Annex I of the 1982 Convention on the Law of the Sea (3), which stresses the need for international cooperation in the conservation, management and utilization of living aquatic resources, especially of migratory species. This does not, however, enforce any regulations (9). Fortunately, the blue shark is a prolific species with good rebound potential, and the abundance and wide distribution of this species offers a reasonable buffer against extinction (7).
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Relevance to Humans and Ecosystems

Benefits

Blue sharks are considered by commercial fishermen (particularly those of mackerel, pilchard, and salmon) to be a nuisance species, as they prey on target species and ruin nets by becoming entangled in them.

Due to their pelagic lifestyle, blue sharks are not often encountered by divers and swimmers. They are considered to be a dangerous species, however, with the International Shark Attack File recording a dozen confirmed, unprovoked attacks (4 fatal), and nearly two dozen additional, provoked attacks.

Negative Impacts: injures humans (bites or stings)

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Although mainly caught indirectly as bycatch on long lines and in gill nets, blue sharks, like many shark species, are valued commercially for their fins, squalene (liver oil), skin, cartilage, and their teeth and jaws. Their meat is less valued because of its high ammonia content.

Positive Impacts: food ; body parts are source of valuable material

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Importance

fisheries: minor commercial; gamefish: yes; price category: medium; price reliability: reliable: based on ex-vessel price for this species
  • Food and Agriculture Organization of the United Nations 1992 FAO yearbook 1990. Fishery statistics. Catches and landings. FAO Fish. Ser. (38). FAO Stat. Ser. 70:(105):647 p. (Ref. 4931)
  • International Game Fish Association 1991 World record game fishes. International Game Fish Association, Florida, USA. (Ref. 4699)
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Wikipedia

Blue shark

The blue shark (Prionace glauca) is a species of requiem shark, in the family Carcharhinidae, that inhabits deep waters in the world's temperate and tropical oceans. Preferring cooler waters,[3] blue sharks migrate long distances, such as from New England to South America.

Although generally lethargic, they can move very quickly. Blue sharks are viviparous and are noted for large litters of 25 to over 100 pups. They feed primarily on small fish and squid, although they can take larger prey. Maximum lifespan is still unknown, but it is believed that they can live up to 20 years. [4]

Anatomy and appearance[edit]

Illustration of Prionace glauca.

Blue sharks are light-bodied with long pectoral fins. Like many other sharks, blue sharks are countershaded: the top of the body is deep blue, lighter on the sides, and the underside is white. The male blue shark commonly grows to 1.82 to 2.82 m (6.0 to 9.3 ft) at maturity, whereas the larger females commonly grow to 2.2 to 3.3 m (7.2 to 10.8 ft) at maturity.[5] Large specimens can grow to 3.8 m (12 ft) long. Occasionally, an outsized blue shark is reported, with one widely printed claim of a length of 6.1 m (20 ft), but no shark even approaching this has been confirmed in this species.[5] The Blue Shark is fairly elongated and slender in build and typically weighs from 27 to 55 kg (60 to 121 lb) in males and from 93 to 182 kg (205 to 401 lb) in large females.[6][7][8] Occasionally, a female in excess of 3 m (9.8 ft) will weigh over 204 kg (450 lb). The heaviest reported weight for the species was 391 kg (862 lb).[9] The blue shark is also ectothermic.

Reproduction[edit]

Back of blue shark

They are viviparous, with a yolk-sac placenta, delivering four to 135 pups per litter. The gestation period is between 9 and 12 months. Females mature at five to six years of age and males at four to five. Courtship is believed to involve biting by the male, as mature specimens can be accurately sexed according to the presence or absence of bite scarring. Female blue sharks have adapted to the rigorous mating ritual by developing skin three times thicker than male skin.[3]

Ecology[edit]

Range and habitat[edit]

The blue shark is an oceanic and epipelagic shark found worldwide in deep temperate and tropical waters from the surface to about 350 meters.[10] In temperate seas it may approach shore where it can be observed by divers, while in tropical waters it inhabits greater depths. It lives as far north as Norway and as far south as Chile. Blue sharks are found off the coasts of every continent, except Antarctica. Its greatest Pacific concentrations occur between 20° and 50° North but with strong seasonal fluctuations. In the tropics it spreads evenly between 20° N and 20° S. It prefers waters with a temperature range of 7–16 °C (45–61 °F) but will tolerate temperatures of 21 °C (70 °F) or above. Records from the Atlantic show a regular clockwise migration within the prevailing currents.[3]

Feeding[edit]

Squid are important prey for blue sharks, but their diet includes other invertebrates such as cuttlefish and pelagic octopuses, as well as lobster, shrimp, crab, a large number of bony fishes, small sharks, mammalian carrion and occasional sea birds. Whale and porpoise blubber and meat have been retrieved from the stomachs of captured specimens and they are known to take cod from trawl nets.[3] The sharks have been observed and documented working together as a "pack" to herd prey into a concentrated group from which they can easily feed. Blue sharks rarely eat tuna, which have been observed taking advantage of the herding behavior to opportunistically feed on escaping prey. It is interesting to note that the observed herding behavior was undisturbed by different species of shark in the vicinity that normally would pursue the common prey.[11] The blue shark can swim at fast speeds, allowing it to catch up to prey easily. Triangular teeth allows the Blue shark to easily catch slippery prey.

Predators[edit]

. Young and smaller individuals may get eaten by larger sharks such as the great white shark and the tiger shark. This shark may host several species of parasites. For example, the blue shark is the definite host of the tetraphyllidean tapeworm, Pelichnibothrium speciosum (Prionacestus bipartitus). It becomes infected by eating intermediate hosts, probably opah (Lampris guttatus) and/or longnose lancetfish (Alepisaurus ferox).[12]

Relationship to humans[edit]

It is estimated that 10 to 20 million of these sharks are killed each year as a result of fishing. The flesh is edible, but not widely sought after; it is consumed fresh, dried, smoked and salted and diverted for fishmeal. There is a report of high concentration of heavy metals (Hg, Pb) in the edible flesh. [13] The skin is used for leather, the fins for shark-fin soup and the liver for oil.[3] Blue sharks are occasionally sought as game fish for their beauty and speed.

Blue sharks rarely attack humans. From 1580 up until 2013 the blue shark has been implicated in only 13 attacks upon humans, four of which ended fatally. [14]

In captivity[edit]

Blue sharks, like most pelagic sharks, tend to fare poorly in captivity. Attempts at keeping them using circular tanks with long glide paths, and pools with 3 meters (9.8 ft) central depth gently ascending to zero depth have met with mixed results at best; most specimens last less than 30 days. As with other pelagic sharks, they seem to have trouble avoiding walls or other obstacles. In 1969 at Sea World San Diego, several blue sharks were put in circular tanks (15 m diameter, 2.1 m deep) for three months. The blue sharks did fairly well until bull sharks were added to the tank; the bull sharks ate the blue sharks. The captivity record for blue sharks as of 2008 was held by The New Jersey Aquarium for a specimen that lasted roughly 7 months before expiring of an apparent bacterial infection.[15]

See also[edit]

For a topical guide to this subject, see Outline of sharks.

References[edit]

  1. ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Chondrichthyes entry)". Bulletins of American Paleontology 364: 560. Retrieved 2008-01-09. 
  2. ^ Stevens (2005). "Prionace glauca". IUCN Red List of Threatened Species. Version 2010.4. International Union for Conservation of Nature. Retrieved April 10, 2011. 
  3. ^ a b c d e Leonard J. V. Compagno (1984). Sharks of the World: An annotated and illustrated catalogue of shark species known to date. Food and Agriculture Organization of the United Nations. pp. 521–524, 555 – 61, 590. 
  4. ^ Sharks, Emerging Species Profile Sheets, published by the Department of Fisheries and Aquaculture, Government of Newfoundland and Labrador; undated
  5. ^ a b FLMNH Ichthyology Department: Blue Shark. Flmnh.ufl.edu. Retrieved on 2012-12-19.
  6. ^ Blue Shark (Prionace glauca) – Ireland's Wildlife. Irelandswildlife.com (2011-07-21). Retrieved on 2012-12-19.
  7. ^ Sharks – Greenland (Somniosus microcephalus), Shortfin Mako (Isurus oxyrinchus), Blue Shark (Prionace glauca), Basking Shark (Cetorhinus maximus), and Porbeagle (Lamna nasus). fishaq.gov.nl.ca
  8. ^ Sea Angling in Ireland – Blue Shark. Sea-angling-ireland.org (2006-10-21). Retrieved on 2012-12-19.
  9. ^ Summary of Large Blue Sharks Prioncae glauca (Linnaeus, 1758) in progress. elasmollet.org (March 2008)
  10. ^ Froese, Rainer and Pauly, Daniel, eds. (2006). "Prionace glauca" in FishBase. 9 2006 version.
  11. ^ Monique, Fallows (29 January 2013). "Blue Sharks Feeding on Anchovy Baitball". Apex Predators Blog. Retrieved 6 February 2013. 
  12. ^ Scholz, Tomáš; Euzet, Louis; Moravec, František (1998). "Taxonomic status of Pelichnibothrium speciosum Monticelli, 1889 (Cestoda: Tetraphyllidea), a mysterious parasite of Alepisaurus ferox Lowe (Teleostei: Alepisauridae) and Prionace glauca (L.) (Euselachii: Carcharinidae)". Systematic Parasitology 41 (1): 1–8. doi:10.1023/A:1006091102174. 
  13. ^ Lopez, S., Abarca, N., Meléndez, R., Heavy Metal Concentrations of two highly migratory sharks (Prionace glauca and Isurus oxyrinchus)in the southeastern Pacific waters: comments on public health and conservation. Tropical Conservation Science Vol. 6 (1) 126-137, 2013. Read more at http://news.mongabay.com/2013/0318-kimbrough-tcs-sharks.html#oW2do4oAQLssXMSk.99
  14. ^ https://www.flmnh.ufl.edu/fish/sharks/statistics/species3.htm
  15. ^ Blue Shark (Prionace glauca) in Captivity. elasmollet.org (2007)
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