Grey Nurse Shark

The sand tiger shark is one of the best-studied of the shark species. They are the only sharks known to gulp air at the surface and store it in their stomach to provide buoyancy (2). These sharks generally mate between October and November and courtship can take a long time, with the male aggressively nipping his potential mate (3). Females are ovoviviparous, giving birth to two large pups every two years. Pups hatch out of their eggs within the oviduct of the mother's reproductive system, one in each oviduct, and then feed on eggs that the female continues to produce (6). Over nine months to a year, the pups grow within their mother feeding on hundreds to thousands of eggs (6) and, by the time they are born, measure up to a metre long (3). During the day they are found near caves and ledges (5), hovering just above the surface either singly or in small groups (3). These fairly docile sharks are sluggish and, despite a ferocious reputation, feed mainly on fish (5).

Despite protection in some countries such as Australia (2) and the United States (3), this species appears to be in decline (2). Management plans urgently need to be implemented in order to safeguard the future of these elegant coastal dwellers.

This stocky shark has a conical nose and a slightly flattened head (3). It is a dark brown or beige colour above, with blotches of darker colour, and paler underneath (4). The teeth of this species are especially distinctive, having a fang-like appearance and being visible even when the mouth is shut (5). There are two dorsal fins, which are a similar size to the anal fin; the upper lobe of the tail is larger than the lower one (3). Sharks have a sixth sense that enables them to detect electric currents, and the receptive pores are located on the under surface of the sand tiger's snout (5).

Inhabits shallow coastal waters from the surf zone to a depth of 60 metres (5).

A widespread range encompasses all subtropical and tropical oceans (6), with the possible exception of the eastern Pacific (2).

Classified as Vulnerable (VU) on the IUCN Red List (1).

This species of shark is particularly vulnerable to overfishing due to its low reproduction rate (2). Despite a widespread distribution, populations are now isolated and, where there is data available, the species is thought to be in decline. In the past, the sand tiger shark has been hunted throughout its range, and the flesh is particularly prized in Japan (3). The oil and fins are also in demand; in the 18th and 19th Centuries the shark was persecuted in large numbers for its liver oil that was used in lighting (7). Individuals tend to group in coastal areas at certain times of the year, making them especially vulnerable to fishing (3).