BLUE SHARK FACTS

IDENTIFICATION

The blue shark is one of the most easily recognisable sharks. It has a distinct colour – a deep indigo blue from above and a vibrant blue on its sides, changing to white underneath.

The large pectoral fins are also easy to spot, as they are as long as the distance between the tip of the snout and the last gill slit.

The blue shark is a long, slender shark, reaching 3.8 metres (13ft) in length. It is likely the most prolific of the large shark species as it is abundant throughout its range. The blue shark has a weak keel on the caudal peduncle, and the upper lobe of the caudal fin is larger than the lower.

The teeth on both the lower and upper jaw have triangular cusps with smooth or finely serrated edges.

DIET

The diet of this shark includes many types of fish and squid, and may sometimes eat seals. Although flatfishes make up part of the diet, blue sharks predominantly eat pelagic fish such as herrings, cod, haddock, pollack, mackerel and whiting.

Fish caught on longlines are often attacked and consumed by blue sharks, which in turn often become ensnared in the fishing gear.

REPRODUCTION

The blue shark is a viviparous species, nourishing the young in the uterus and giving birth to live pups. The newborn pups measure 40-51cm (16-20 inches) in length, and litters usually consist of between 25 and 50 individuals. Litters of up to 135 pups have been reported.

Females reach sexual maturity at a size of 2.2 to 3.2 metres (7-11ft), while for males it is achieved at lengths of 1.8 to 2.8 metres (6-9ft). After copulation the females may retain and nourish the spermatozoa in the oviducal gland for months or even years while she awaits ovulation. Once the eggs have been fertilised, there is a gestation period of between nine and 12 months.