Blacktip topeshark  (Hypogaleus hyugaensis)

The blacktip topeshark is classified as Near Threatened (NT) on the IUCN Red List (1).

The blacktip topeshark (Hypogaleus hyugaensis) is a small, slender hound shark (a shark of the family Triakidae) with a greyish-bronze body, a moderately long snout, and large, oval eyes (2) (3) (4). As the common name suggests, the caudal and upper dorsal fins have blackish tips (2). The second dorsal fin is smaller than the first, although it is larger than the anal fin, while the caudal fin has a much larger upper than lower lobe (3) (4). The blacktip topeshark differs from the tope shark, Galeorhinus galeus, in having a smaller notch on the upper lobe of the caudal fin, and a relatively larger second dorsal fin (3).

The blacktip topeshark has a patchy distribution in the Indian Ocean and western Pacific Ocean. It has been recorded in waters around Japan, Taiwan, Australia, South Africa, Tanzania and Kenya, and may possibly occur in the Arabian Gulf (1) (2) (4). However, the exact extent of this species’ distribution is difficult to determine, as it may have been inadequately surveyed in deeper waters (1) (2) (4).

This species is still relatively poorly known, but is believed to inhabit fairly deep water in tropical and subtropical areas, being found near the ocean bottom at depths of 40 to 230 metres (4). Some surveys have found the blacktip topeshark to be most common at depths of 50 to 80 metres, but this may be affected by the smaller number of samples from deeper waters (5).

Relatively little is known about the biology of the blacktip topeshark (1) (2), although it has been reported to feed on fish and cephalopods, such as squid. This species gives birth to live young, the embryos being nourished inside the female through a placenta during the later stages of development (1) (2) (4) (5). Births are thought to be seasonal (1) (2), occurring around February in waters off Western Australia (1) (2) (3), and in December off South Africa (4). Some estimates put the gestation period at over 12 months (3) (4), but it is generally thought to be closer to 10 to 12 months (1) (2) (5). The female blacktip topeshark gives birth to between 3 and 15 young, every other year (1) (2) (5). The young sharks measure around 30 to 35 centimetres in length at birth (1) (2) (4) (5), and are thought to mature at a length of about 98 centimetres in males and 102 centimetres in females (1) (2).

Although the blacktip topeshark is of only relatively minor importance in fisheries, its patchy distribution and relatively low abundance make it vulnerable to any increase in fishing pressure (1) (2), particularly in deeper waters (5). It is not a specific target of fisheries, but is caught as bycatch throughout its range (1) (2) (3) and is sometimes used for human consumption (4). However, it is often discarded when caught and may be difficult to identify, so data on landings may not represent the true extent to which the blacktip topeshark is being caught (5).

There are currently no specific conservation measures targeted at this small shark (1) (2). However, the blacktip topeshark may receive some protection within Marine Protected Areas such as the Great Barrier Reef Marine Park, Australia (6), and it may also benefit from restrictions in place for the shark fishery in Western Australia (1) (2).

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

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To find out more about shark conservation see:

• Save Our Seas Foundation:
  http://www.saveourseas.com/
• Project AWARE:
  http://www.projectaware.org/
• Shark Trust:
  http://www.sharktrust.org/
• IUCN / SSC Shark Specialist Group:
  http://www.iucnssg.org/