Dipturus wengi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RAJIDAE

Scientific Name: Dipturus wengi
Species Authority: Séret & Last, 2008
Common Name/s:
English Weng's Skate
Taxonomic Notes: Weng’s Skate (Dipturus wengi) appears to belong to a complex of closely related skate species that differ only slightly in their morphology (Last and Stevens 2009). Records of this species from off Indonesia and the Philippines are likely a different species.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2011
Date Assessed: 2010-12-02
Assessor/s: Bigman, J.S., Ebert, D.A. & Kyne, P.M.
Reviewer/s: Fowler, S.L., Mull, C. & Simpfendorfer, C.
Justification:

Weng’s Skate (Dipturus wengi) is a poorly known deepwater skate that is endemic to eastern and southeastern Australia, although its full distribution is uncertain. It occurs on the continental slope in depths of 485–1,165 m (primarily 600–1,000 m). The distribution of Weng’s Skate overlaps with a number of commercial fisheries along the east coast of Australia. Most notably, fishing pressure has been historically high on the upper continental slope off southeastern Australia, where declines have been demonstrated in the upper slope skate community. However, the species is naturally less common in this region, and is more abundant in the north of its range, in deep tropical waters off Queensland. Fishing pressure is much lower in this region, and in fact there has been no demersal trawling recently in the Commonwealth managed Coral Sea Fishery, the management area of which overlaps with Weng's Skate. As such, the species has refuge in unfished or only lightly fished areas in the north of its range and in the deeper parts of its bathymetric occurrence. Despite the lack of information concerning its population size and structure, life history and ecology, an assessment of Least Concern is warranted. A caveat though is that bycatch levels and any changes or expansion in deepwater fisheries need to be monitored.

Geographic Range [top]

Range Description:Weng’s Skate is a wide-ranging species distributed along the continental slope off eastern Australia from west of Lihou Reef and Cays, Queensland (16º54’S, 151º30’E) and southward to Bicheno, Tasmania (ca 42ºS, 148ºE). It has been found off Queensland, New South Wales, and eastern Tasmania, but has not been confirmed in the Great Australian Bight or off Western Australia. It likely occurs off western Tasmania, but populations off Western Australia (between Albany and Rowley Shoals) may be a closely related species (Séret and Last 2008, Last and Stevens 2009).
Countries:
Native:
Australia (New South Wales, Queensland, Tasmania)
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern; Pacific – southwest; Pacific – western central
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: There are no population estimates for Weng’s Skate. It is however more common in the north of its range (in the tropical zone) and rarer in the south (in the cool temperate zone) (Last and Stevens 2009).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Weng’s Skate occurs most commonly along the continental slope in the tropical waters of Queensland and more rarely in cool temperate waters, in depths of 485–1,165 m, but mostly between 600–1,000 m (Séret and Last 2008, Last and Stevens 2009). It reaches at least 128 cm total length (TL) with a size-at-birth of about 20 cm TL (Last and Stevens 2009), but its biology is poorly known.
Systems: Marine

Threats [top]

Major Threat(s): The distribution of Weng’s Skate overlaps with a number of commercial fisheries along the east coast of Australia. Most notably, fishing pressure has been historically high on the upper continental slope off southeastern Australia. The Commonwealth Trawl Sector of the Commonwealth managed Southern and Eastern Scalefish Fishery (SESSF) operates in the southern portion of the range of Weng's Skate. In trawl surveys within this region at depths of 200–650 m over a 20 year period, Graham et al. (2001) demonstrated a decline in slope skate species of >83%. Weng's Skate (as Raja sp. I) was a small component of catches in the deeper depth zone and has no doubt been impacted by the level of fishing pressure on the slope off southeastern Australia. However, some spatial closures and deeper depths may represent refuges for the species, although this requires investigation.

The northern part of the range of Weng's Skate, where it is apparently more common (Last and Stevens 2009) overlaps with the Commonwealth managed Coral Sea Fishery. This is a relatively small-scale fishery with only four active vessels in the Line and Trap, and Trap and Trawl Sectors of the fishery in the 2008–09 fishing season (Woodhams et al. 2010). There was no trawl activity in the fishery during the 2007–08 and 2008–09 fishing seasons (Woodhams et al. 2010), but the extent to which line fishing interacts with this species is unclear. Given that there is no trawling at present in the fishery, and the overall low effort of the fishery, it is not likely to be having any significant impact upon this species.

Conservation Actions [top]

Conservation Actions: There are no conservation actions in place at this time for Weng’s Skate. It may have some refuge in spatial closures on the southeastern Australian continental slope (although these represent only a very small area of available habitat). Bycatch levels of this, and other skates should be monitored in commercial fisheries which overlap with the distribution of the species. Furthermore, research is required into the life history and ecology of the species.

Bibliography [top]

Graham, K.J., Andrew, N.L. and Hodgson, K.E. 2001. Changes in the relative abundances of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing. Journal of Marine and Freshwater Research 52: 549-561.

IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.2). Available at: http://www.iucnredlist.org. (Accessed: 10 November 2011).

IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.

Last, P.R. and Stevens, J.D. 2009. Sharks and Rays of Australia. Second Edition. CSIRO Publishing, Collingwood, Australia.

Séret, B. and Last, P.R. 2008. A new Australian skate of the genus Dipturus (Rajoidei: Rajidae). In: Last, P.R., White, W.T., Pogonoski, J.J., and Gledhill, D.C (eds), Descriptions of New Australian Skates, CSIRO Marine and Atmospheric Research Paper No. 021.

Woodhams, J., Chambers, M. and Pham, T. 2010. Coral Sea Fishery. pp 71-86. In: Wilson D.T., Curtotti, R., and Begg, G. A (eds), Fishery status reports 2009: status of fish stocks and fisheries managed by the Australian Government, Australian Bureau of Agricultural and Resource Economics – Bureau of Rural Sciences, Canberra.

Citation: Bigman, J.S., Ebert, D.A. & Kyne, P.M. 2011. Dipturus wengi. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 20 April 2014.
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