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).
Also known as
blacktip houndshark, blacktip tope, blacktip tope shark, lesser soupfin shark, pencil shark, western school shark.
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).
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).
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).
In fish, an unpaired fin on the under surface of a fish, behind the anus.
In the fishing industry, the part of the catch made up of non-target species.
The tail fin of a fish.
From the Greek for ‘head-foot’, a class of molluscs that occur only in marine habitats. All species have grasping tentacles, and either an internal or external shell. Includes nautiloids, cuttlefish, squids, octopuses, and extinct ammonites and belemnites.
A region of relatively shallow water, not usually deeper than 200 metres, surrounding each of the continents.
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
The state of being pregnant; the period from conception to birth.
Fowler, S.L., Cavanagh, R.D., Camhi, M., Burgess, G.H., Cailliet, G.M., Fordham, S.V., Simpfendorfer, C.A. and Musick, J.A. (2005) Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. IUCN/SSC Shark Specialist Group, IUCN, Gland. Available at: http://data.iucn.org/dbtw-wpd/edocs/2005-029.pdf
Daley, R.K., Stevens, J.D., Last, P.R. and Yearsley, G.K. (2002) Field Guide to Australian Sharks and Rays. CSIRO Publishing, Collingwood, Australia.
Compagno, L.J.V. (1984) Sharks of the World. An Annotated and Illustrated Catalogue of Shark Species Known to Date. Vol. 4: Part 2: Carcharhiniformes. Food and Agriculture Organization of the United Nations, Rome. Available at: ftp://ftp.fao.org/docrep/fao/009/ad123e/AD123e18.pdf
Simpfendorfer, C.A., Kitchingman, A.M. and McAuley, R.B. (2002) Distribution, biology and fisheries importance of the pencil shark, Hypogaleus hyugaensis (Elasmobranchii: Triakidae), in the waters off south-western Australia. Marine and Freshwater Research, 53: 781-789.
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