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Dipturus acrobelus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RAJIDAE

Scientific Name: Dipturus acrobelus
Species Authority: Last, White & Pogonoski, 2008
Common Name(s):
English Deepwater Skate, Brown Bight Skate
Taxonomic Notes:

The Deepwater Skate (Dipturus acrobelus) was previously misidentified as Bight Skate Raja gudgeri (Last et al. 1983).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2011
Date Assessed: 2010-11-12
Assessor(s): Robbins, R. & Huveneers, C.
Reviewer(s): Ebert, D.A. & Kyne, P.M.
Justification:
The Deepwater Skate (Dipturus acrobelus) is a little-known, large skate species reported from southern Australian waters in depths of 450–1,330 m, although mainly in 800–1,000 m. The Deepwater Skate is found on the continental slope off southern Australia from east of Crowdy Head, New South Wales to the Great Australian Bight, Western Australia, including Tasmania. However, the western extent of its range is likely to increase through additional surveys of the continental slope off southwestern Australia. The species may be vulnerable to population declines from fishing pressure due to its large size. There are little specific details available regarding its ecology or life history. The Southern and Eastern Scalefish and Shark Fishery (including the East Coast Deepwater Trawl, Great Australian Bight and Commonwealth Trawl Sectors) operates within this species’ range off southern and eastern Australia, in which the species might be taken as bycatch. However, the species has a relatively wide distribution and the estimated annual catch levels are relatively low. Additionally, since this species is most commonly found in waters of 800–1,000 m and that deep water trawling is currently prohibited to trawl operations deeper than 750 m, the impact of these fisheries on the Deepwater Skate is likely to be small. As such, the species is assessed as Least Concern. However, research is required to accurately define its range, as well as its population size/structure, capture in fisheries, and population trends. Given its occurrence in areas where deepwater trawl fisheries operate and the general vulnerability of large skates to overfishing, bycatch levels need to be monitored.

Geographic Range [top]

Range Description: The Deepwater Skate is endemic to Australia and is found on the continental slope off southern Australia from east of Crowdy Head, New South Wales to the Great Australian Bight, Western Australia, including Tasmania. However, the full extent of its distribution, particularly to the west, is uncertain (Last and Stevens 2009) with the western extent of its range likely to increase through additional thorough surveys of the continental slope off southwestern Australia.
Countries:
Native:
Australia (New South Wales, South Australia, Tasmania, Victoria, Western Australia)
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern; Pacific – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The Deepwater Skate is apparently common throughout its range (Last and Stevens 2009), however details of population size, structure, or trends is currently unavailable.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology:

The Deepwater Skate is demersal and occurs in a depth range of 446–1,328 m although mainly in 800–1,000 m (Last and Stevens 2009). There are no species-specific details available on habitat. The Deepwater Skate attains at least 137 cm total length (TL); adolescent males range 77.6–85.5 cm TL; males reach maturity at 89–95 cm TL; smallest juvenile 20.2 cm TL (Last et al. 2008). There are no other details available regarding its ecology or life history.

Systems: Marine

Use and Trade [top]

Use and Trade: The Deepwater Skate is not known to be traded. However, while most skates caught off southeastern Australia used to be discarded, there is now an increasing trend for the larger (adult) ones to be retained for the local market.

Threats [top]

Major Threat(s): The Deepwater Skate might be taken as bycatch within three of the four sectors of the Commonwealth managed Southern and Eastern Scalefish and Shark Fishery (SESSF) (that is, the East Coast Deepwater Trawl, Great Australian Bight Trawl (GABTS), and Commonwealth Trawl sectors). The current known distribution of this species overlaps entirely with these fisheries. The mean annual catch rate of the Deepwater Skate in the SESSF between 2000 and 2006 of 16 tonnes included 13 tonnes from the 200–599 depth range (Walker and Gason 2007). The GABTS upper continental slope sub-fishery operates in waters 200–700 m depth, so only in the shallower regions of this species’ known range. The GABTS deepwater slope sub-fishery operates in waters from 700–1,000 m. However, waters deeper than 750 m are currently closed to protect stocks of Orange Roughy (Hoplostethus atlanticus) in both the GABTS and the Commonwealth Trawl Sector. Since the Deepwater Skate is most commonly found in waters 800–1,000 m, the impact of these fisheries on it is likely to be small. However, considering the bycatch level within the 200–599 m depth range and that the Deepwater Skate mainly occurs at deeper depths, the deepwater trawl fisheries are likely to be of concern to this species should the deep water be reopened in the future. Fishing effort in the East Coast Deepwater Trawl sector over recent years has been extremely low and is therefore of little concern, but should be monitored for increases in the future.

Conservation Actions [top]

Conservation Actions:

No species-specific conservation actions are currently in place for the Deepwater Skate. Given the vulnerability of large skates to overfishing, bycatch levels need to be monitored.   


Citation: Robbins, R. & Huveneers, C. 2011. Dipturus acrobelus. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 September 2014.
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