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. 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.

Abundant oceanic shark, in waters from the surface to about 350 meters. Common off the Otago Coast in summer. These sharks swim with a thrust and glide motion and are not suitable for keeping in an Aquarium.

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.

They are viviparous, with a yolk-sac placenta, 4-135 (average about 40) young born at 35-50 cm. The gestation period is between 9 and 12 months. Females mature at 5 to 6 years of age and males at 4 to 5. 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 3 times thicker than male skin. May be dangerous to humans. It is estimated that 10 to 20 million of these species 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. The skin is used for leather, the fins for shark-fin soup and the liver for oil.Blue sharks are occasionally sought as game fish for their beauty and speed. As of 2012 there have been 13 recorded attacks on humans and 4 fatalities.

NZ Marine Fishes: Paul
Froese, Rainer and Pauly, Daniel, eds. (2006). "Prionace glauca" in FishBase. 9 2006 version. Monique, Fallows (29 January 2013). "Blue Sharks Feeding on Anchovy Baitball". Apex Predators Blog. Retrieved 6 February 2014. 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. 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. ISAF Statistics on Attacking Species of Shark (http://www.flmnh.ufl.edu/fish/sharks/statistics/species3.htm (accessed 06/02/14)