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Trees- ShrubsBlue Shark ( Prionace glauca )
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The Blue shark has a slim body with an elongated tail fin, large eyes and a long snout (1). It can grow to lengths of up to 4 meters and weigh up to 200kg (2). It has a dark blue body which fades to white on its underside (4).
It is one of the most abundant and widespread of sharks, but it is also on of the most heavily fished in the world (3). Much of its losses are as a result of bycatch, and the IUCN (3) estimate the annual mortality to be 10 to 20 million individuals. Unfortunately data is not sufficient to asses the scale and effects of the population decline, but a removal of a species in these quantities could have serious consequences for the ocean ecosystem (1).
Blue sharks are often seen cruising slowly and sluggishly but it is also capable of rapid movement when excited or feeding (7). It has been recorded circling its prey and taking test bites before moving in to finally attack (1).
The Blue shark has a lifespan of up to 20 years and reaches sexual maturity between 5 and 6 years (5). The species is viviparous (1) and has a gestation period of 9 to 12 months. Pups are born at a length of 40cm and there are usually 25- 50 per litter, but there have been instances of anything between 4 and 135 pups per litter (5). The variation in litter size is most likely due to the size of the female (6).
Offshore cool surface waters, or deeper cool water down to 150m in the tropics, it may come further inshore at night (4).
The Blue shark is probably the widest ranging of shark species, inhabiting temperate and tropical waters from 50°N to 40°S around the globe (2).
This is a highly migratory species that travel clockwise around the Atlantic Ocean, following the Gulf Stream to Europe, taking various currents down the European and African coasts, and the Atlantic North Equatorial Current to the Caribbean region (3). They also undertake short term migration inshore during the night (3).
Bony fish and squid
IUCN Red List Status: Near Threatened (Assessed 2000) (3).
UNCLOS
UNFSA
Bern Convention Appendix III (8)
Barcelona Convention Annex III
Description written by Jo Pollett (2009)
(1) Stevens, J., 2008. Blue Shark – Prionace glauca – Information – ARKive – facts and status. [Online] Available at: http://www.arkive.org/blue-shark/prionace-glauca/info.html [Accessed 19 August 2009].
(2) Australian Museum, 2005. Blue Shark, Prionace glauca (Linnaeus, 1758) – Australian Museum. [Online] Available at: http://australianmuseum.net.au/Blue-Shark-Prionace-glauca-Linnaeus-1758/ [Accessed 19 August 2009].
(3) Stevens, J. 2000. Prionace glauca. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. <www.iucnredlist.org>. Downloaded on 19 August 2009.
(4) Centre for Coastal Studies and Aquaculture, University of New Brunswick, 2005. Blue Shark. [Online] Available at: http://new-brunswick.net/new-brunswick/sharks/species/blue.html [Accessed 19 August 2009].
(5) Prionace glauca, Blue Shark – MarineBio.org. Retrieved Wednesday, August 19, 2009, from http://marinebio.org/species.asp?id=35.
(6) Cooper, P., 2006. Florida Museum of Natural History: Ichthyology Department. Biological Profiles – Blue. [Online] Available at: http://www.flmnh.ufl.edu/fish/gallery/Descript/BlueShark/BlueShark.html [Accessed 19 August 2009].
(7) 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.
(8) Europe, C.o., 2002. Convention on the conservation of European wildlife and natural habitats: Bern Convention. [Online] Available at: http://conventions.coe.int/Treaty/FR/Treaties/Html/104-3.htm [Accessed 19 August 2009].
