Short-tail nurse shark  (Pseudoginglymostoma brevicaudatum)

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

A sluggish, bottom-dwelling species, the little known short-tail nurse shark is only found in the western Indian Ocean. With a short, flattened body and broad, rounded pectoral fins, the distinctive short-tail nurse shark contrasts starkly with the typical powerful, streamlined shark form. As its name suggests, the caudal fin is shorter than that of similar species, comprising only one quarter of the total body length (3). Small, inconspicuous eyes sit behind a bluntly rounded snout, a small mouth and two short barbels that are used to sense prey under the sea bed (4). Adapted to life on the ocean floor, the body of this well camouflaged predator is a cryptic, uniform dark brown colour across the upperparts, with little or no markings, fading to white on the underside (5).  

Endemic to the western Indian Ocean, the short-tail nurse shark is found in two distinct populations, off the coast of Tanzania and Kenya in East Africa, and in the waters surrounding Madagascar. A third population may occur around the islands of Mauritius and the Seychelles, but the species’ status there is unknown (1) (2).

Very little is understood about the habitat requirements of the short-tail nurse shark except that it is known to inhabit the sea floor of coastal tropical waters in or near coral reefs (1).

Lazy and sluggish during the day, the short-tail nurse shark typically lies motionless on the ocean floor, often congregating in small groups (6). At night, however, this nocturnal predator roams widely, foraging for ground-dwelling crustaceans, urchins, squid and octopuses. In common with other nurse sharks, it has unique feeding apparatus, with a small mouth and enlarged pharynx that allows the shark to feed with a suction method. Utilising this ability, the short-tail nurse shark will cup its mouth over a crevice or burrow to create a vacuum, and suck up its prey (3). 

The breeding biology of the short-tail nurse shark is poorly understood, but in contrast with other nurse sharks, which give birth to live young, eggs laid by captive females indicate the species is oviparous. Captive individuals may live for up to 33 years, with maturity reached when around 56 centimetres in length (4).

Already restricted in range, the short-tail nurse shark is further threatened by fishing (1). It may be directly fished for its flesh, which can be dried and salted for sale as food, or for its tough skin, which is used to produce leather (5). Fisheries are often driven by the demand for shark fins in Southeast Asia, where they are considered a delicacy, and the fins of the short-tail nurse shark can be sold for a high price (1). In Zanzibar, the species is estimated to be found in an alarming 84 percent of catches, making it one of the most intensively fished species in the surrounding waters (7). In common with most other sharks, the short-tail nurse shark is further threatened by accidental bycatch in longline and gillnet fisheries. Consequently, the short-tail nurse shark is believed to have suffered dramatic declines (1).  

There are currently no known conservation measures in place for this poorly known species. In the absence of binding international treaties for the management of sharks, including the regulation or outlawing of finning, unsustainable fishing continues unabated(8). However, conservation measures aimed at developing Marine Protected Areas will undoubtedly protect the short-tail nurse shark and its habitat, while some nations continue to revise their fisheries legislation. Furthermore, many unsustainable activities, such as dynamite fishing and the use of poison, which damage coral reef habitat, have already been prohibited (7). However, further research into the species’ biology and trade is required, and public awareness programmes are needed to highlight the plight of this enigmatic species (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the threats to sharks, see:

• The Shark Trust:
  http://www.sharktrust.org/
• The Shark Research Institute: 
  http://www.sharks.org/
• Conservation International: 
  http://www.conservation.org/learn/biodiversity/species/profiles/sharks/Pages/threats.aspx