Odontaspis ferox (Australian subpopulation)http://dx.doi.org/10.2305/IUCN.UK.2003.RLTS.T42835A10757544.en
|Scientific Name:||Odontaspis ferox (Australian subpopulation)|
|Species Authority:||(Risso, 1810)|
See Odontaspis ferox
Carcharias ferox (Risso, 1810)
Odontapsis herbsti (Whitley, 1950)
|Red List Category & Criteria:||Vulnerable A2abd+3bd+4abd ver 3.1|
|Assessor(s):||Pollard, D., Gordon, I., Williams, S., Flaherty, A. & Fergusson, I.K. (SSG Australia & Oceania Regional Workshop, March 2003)|
|Reviewer(s):||Shark Specialist Group Australia & Oceania Regional Group (Shark Red List Authority)|
Despite its worldwide distribution, Odontaspis ferox subpopulations and occurrences are fragmented and the species may be naturally rare. Recent evidence of shallow water aggregations in a number of areas suggests that the species may be more susceptible to fishing pressure than previously assumed, and potentially susceptible to coastal habitat impacts as well as to over-exploitation because of its presumed very low reproductive capacity. Increased demersal trawl fisheries in Australia and New Zealand are now operating in areas of possible and known occurrence. Fishery independent surveys indicate an observed decline of over 50% in catches off the east coast of Australia (hence the Vulnerable assessment in these waters), probably the result of commercial fishing operations off New South Wales; similar declines are presumed to have occurred in many other parts of its range impacted by fisheries.
|Range Description:||Important sites in Australia occur off New South Wales on the shelf and upper slope of the south coast|
Native:Australia (New South Wales, Victoria)
|FAO Marine Fishing Areas:||
Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||
Odontaspis ferox lives on or closely associated with the bottom in deep waters along continental and insular shelves and upper slopes (Last and Stevens 1994) to depths to about 850 m (K. Graham, pers. comm). It is occasionally found in shallower water (Last and Stevens 1994). Hutchins filmed underwater video of an individual in 20 m of water at the Cocos-Keeling Islands (B. Hutchins, pers. comm., cited in Pogonoski et al. 2002). There are at least three records from pelagic zones in open waters of the Indian Ocean (Bonfil 1995.) An active-swimming offshore shark, caught and seen as individuals and in small groups (Compagno 2001).
Little is known of the biology of this shark. Its reproduction is presumably similar to that of the grey nurse shark (C. taurus). Compagno (2001) cites an observation which suggests the species practices uterine cannibalism in the form of oophagy.
Size at birth is over 105 cm and males mature at about 275 cm (Compagno 1984). In Australian waters, this species is born at over 100 cm and attains at least 360 cm, but the size at maturity here is unknown (Last and Stevens 1994). A 2.7 m female specimen caught off the Sydney area was judged to be immature, as there was no sign of ovarian development (K. Graham, pers. comm., cited in Pogonoski et al. 2002). Compagno (2001) cites a maximum total length of at least 410 cm and possibly larger; males mature at 275 cm, females at 364 cm. The large oily liver probably has a hydrostatic function (Last and Stevens 1994), and may help the shark to maintain neutral buoyancy while swimming. Stomachs examined have contained small bony fish, cephalopods, crustaceans (Last and Stevens 1994) and small squalid dogfish. A very large O. ferox trawled on the Norfolk Ridge north of New Zealand in 1997 was found to contain a 200 cm seal shark in its stomach. The above information suggests that this species is an opportunistic carnivore (Stewart 1997, cited in Pogonoski et al. 2002). Dentition suggests a more uniform diet of softer prey than in C. taurus (Compagno 2001).
Commercial fishing, whereby this species is taken incidentally, on the outer continental shelf and continental slope is a potential threat to its survival in south-eastern Australian waters.
From the available information, O. ferox was never abundant off NSW, but there is strong evidence that numbers seriously declined between 1972 and 1997. Of the 35 specimens caught by the NSW Fisheries Research Vessel Kapala, 33 were caught between 1975 and 1981 (from 500 slope trawl tows), but only two were taken from about 250 trawl tows made between 1982 and 1997 (K. Graham, pers. comm. cited in Pogonoski et al. 2002).
The NSW upper slope trawl grounds were again surveyed in 1996-97 and the results compared to those from an initial survey made in 1976-77 (Graham et al. 1997). Twelve captures (14 sharks) were made during 246 tows in 1976-77, but only a single juvenile was caught during 165 tows made in 1996-97. Although considered in Pogonoski et al. (2002) as Near Threatened, based on available NSW catch data reassessment to Vulnerable is warranted in Australia.
There has been limited take for aquarium display (Kelly Tarlton’s Aquarium at Auckland NZ) but this species was not successfully kept in captivity.
Protected Species in NSW Waters (since 1984).
In Australia, more study is needed to accurately determine the distributional range, abundance and biology (including possible migrations, sex ratios, fecundity, etc.) of this species.
Any dead specimens landed by commercial fishing (especially trawling) operations should be retained and delivered to the nearest relevant research organisation, so that more biological information can be obtained.
Reported by divers in Cocos-Keeling Islands (Aust.) and also other areas such as the Kermadec Islands (New Zealand) the Mediterranean and Malpelo Island off Columbia. Such community-based dive observations or monitoring may be of use in obtaining information on its biology and knowledge of important habitats in shallow waters.
There is now more evidence that coastal locations are frequented by mature O. ferox on a repetitive seasonal basis, possibly for reproduction. Where identified, these sites deserve stringent protection.
Development of bycatch mitigation measures such as trawl exclusion devices should be undertaken in relevant fisheries.
|Citation:||Pollard, D., Gordon, I., Williams, S., Flaherty, A. & Fergusson, I.K. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Odontaspis ferox (Australian subpopulation). The IUCN Red List of Threatened Species 2003: e.T42835A10757544. http://dx.doi.org/10.2305/IUCN.UK.2003.RLTS.T42835A10757544.en . Downloaded on 10 October 2015.|