|Scientific Name:||Aptychotrema timorensis|
|Species Authority:||Last, 2004|
|Taxonomic Notes:||Previously listed as Aptychotrema sp. nov. A. This species has recently been described (Last 2004) and is a distinct member of the endemic East Indo-West Pacific genus Aptychotrema, of which there are three valid species in Australian waters.|
|Red List Category & Criteria:||Vulnerable B1ab(v) ver 3.1|
|Assessor(s):||Last, P.R. & Kyne, P.M.|
|Reviewer(s):||Heupel, M.R., Simpfendorfer, C.A. & Cavanagh, R.D. (Shark Red List Authority)|
The newly described Aptychotrema timorensis is presently known only from a single specimen taken from the continental shelf at 124 m in the Timor Sea off northern Australia. Population size is estimated to be very small as considerable survey work has failed to find any other specimens. About 650 large Thai pair trawlers from the port of Merauke in West Papua operate in the Arafura Sea, which lies adjacent to the Timor Sea. This fishery is unregulated and batoids compose a substantial portion of the catch, all of which is retained and marketed. Although the impact of fishing on this species is unknown, its potential area of occurrence faces unregulated fishing and this is of particular concern due to its apparent rarity, inferred small population size and limited distribution. While there is considerable uncertainty concerning the status of this species, at this stage a Vulnerable assessment is warranted as a precautionary measure due to inferred pressure on an apparently small and restricted population. Indeed, it could be speculated that serious declines have already occurred, perhaps explaining why only one specimen is known despite extensive survey work in the area. Further information may result in a lower category being more appropriate. Conversely, an increase in fishing pressure would likely drive the species into a higher category.
|Previously published Red List assessments:||
|Range Description:||Presently limited in the Timor Sea off northern Australia. Presumably restricted to the east of its presently known location as ridges would stop the spread of the species to the west.|
Native:Australia (Northern Territory)
|FAO Marine Fishing Areas:||
Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Known only from a single specimen. Population size is estimated to be very small as considerable survey work has failed to find any other specimens.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Single known specimen (58.2 cm TL female) was recorded from the continental shelf at 124 m. Nothing known of the life history characteristics of the species. Presumably aplacental yolksac viviparous and feeds mainly on benthic invertebrates like other members of the genus. Recorded litter sizes of congeneric species are 14 to 16 for A. vincentiana (Haake 1885) and 4 to 18 for A. rostrata (Kyne and Bennett 2002).
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total length cm): Unknown.
Longevity (years): Unknown.
Maximum size (total length): At least 58 cm TL.
Size at birth (cm): Unknown.
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: Unknown.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
The potential area of occurrence of this species faces unregulated fishing and this is of particular concern due to its apparent rarity, inferred small population size and limited distribution.
The area where the only known specimen was collected is near the edge of the Australian fishing zone. The area adjacent is a "free for all" for fishing vessels operating out of eastern Indonesia and there appears to be more activity in this area than was previously thought. About 650 large Thai pair trawlers operate in the Arafura Sea from the port of Merauke in West Papua. This fishery is unregulated and batoids compose a substantial portion of the catch, all of which is retained and marketed.
The species may also enter the bycatch of northern Australian prawn trawl fisheries, but this is likely to be negligible based on the depth at which the type specimen was taken.
Surveys in the Timor and Arafura Seas need to be continued in order to record any future records of the species, and therefore, better document the species' distribution, to determine the extent of occurrence (and any degree of patchiness in the range) and the population size.
The effective implementation of the Australian National Plan of Action for the Conservation and Management of Sharks (Shark Advisory Group and Lack 2004) (under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) will help to facilitate the conservation and sustainable management of all chondrichthyan species in Australia.
|Citation:||Last, P.R. & Kyne, P.M. 2006. Aptychotrema timorensis. The IUCN Red List of Threatened Species 2006: e.T60179A12302471. http://dx.doi.org/10.2305/IUCN.UK.2006.RLTS.T60179A12302471.en . Downloaded on 13 October 2015.|
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