This month we take a journey into the life of the most migratory shark on earth. The Blue Shark.

The name says it all. Blue sharks have a striking metallic blue back, with a white underside. This is a classic example of counter shading. A type of camouflage used by many sharks. This means they’re concealed both from above (as their back matches the blue of the ocean) and below (the white looks similar to the light coming in at the surface).

Their scientific name also describes them very well. The first part of their scientific name (Prionace) is derived from Greek – with ‘prion’ meaning ‘saw’ and ‘akis’ meaning ‘pointed’. This refers to their sharp and serrated triangular teeth. Which are used for gripping hold of slippery prey, such as fish and squid. While the second part (glauca) is Latin for ‘blueish grey’.

The most migratory of all sharks. Blue sharks undertake huge yearly migrations – totalling over 9000km (5700+ miles)! Check out the 60 Second Sharks below to find out all about it.

They are also the most heavily fished shark on the planet. The Blue shark is caught and consumed for meat across the globe. It may be surprising then, to see that they are globally ‘Near Threatened’ on the IUCN Red List of Threatened Species. This is, in part, because Blue Sharks give birth to litters of 4-135 pups (average 35).

This is a relatively large number of pups for a shark. This means that Blue sharks are more resilient than some species to destructive fishing. However, the species is critically endangered in the Mediterranean. If fishing pressures continue, the species is likely to shift into one of the threatened categories globally. Even with larger litters, the populations are unlikely to cope with how many sharks are currently being captured.

Blue sharks are known for being highly inquisitive and curious. When snorkelling or diving near them, they will often come close to investigate people. They come together in groups to feed. Preying on shoals of fish or carrion (i.e., carcasses). They’re most active in the early morning and night. When they cruise slowly on the surface.   

SCIENTIFIC NAME: Prionace glauca

FAMILY:  Carcharhinidae

MAXIMUM SIZE: 3.8m

DIET: Opportunistic feeders. Diet predominately small fishes and squid, but will also eat cuttlefish, lobster, shrimp, carrion and sea birds.

DISTRIBUTION: All temperate and tropical waters. In tropical waters they’re found much deeper, where it’s cooler.

HABITAT: Often found in the open ocean from the surface to depths of 600m. Prefers temperatures of 12-20°C but can tolerate 8–30°C.

CONSERVATION STATUS

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Banner Image - ©Peter de Maagt

Images - ©Frogfish Photography