|Scientific Name:||Urolophus cruciatus|
|Species Authority:||(Lacepède, 1804)|
|Taxonomic Notes:||A comparative study is needed between the different subpopulations present in Tasmania and Victoria to verify that they are the same species as habitat preferences differ dramatically. In Tasmania they are found in very shallow estuarine waters and in Victoria are rarely seen in waters less than 25 m, probably more common > 100 m depth.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Treloar , M.A.|
|Reviewer(s):||Kyne, P.M., Fowler, S.L. & Compagno, L.J.V. (Shark Red List Authority)|
An abundant southeastern Australian endemic stingaree recorded from the continental shelf. Exhibits differential habitat preferences between the south of its distribution (Tasmania) where it is found in shallow water and in the north (Victoria) where it is rarely observed at <25 m depth. Taken as bycatch in the Southern and Eastern Scalefish and Shark Fishery by otter trawl and gillnet, although most trawl effort in this fishery is outside the area of occurrence of the species. It may have undergone declines off New South Wales (NSW), but this represents only the northern extremity of its range. Details of bycatch in Tasmanian inshore commercial and recreational fisheries are not available. Urolophus cruciatus is considered to be common and the lack of trawling in Bass Strait and off the west coast of Tasmania within the depth range of this species warrants a Least Concern assessment. However, continued monitoring of bycatch in the SSESF is required particularly as declines in urolophids have been documented off the NSW coast due to trawling activities. An investigation of inshore catches around Tasmania is also needed.
|Range Description:||Endemic to southeastern Australia: from Tathra (New South Wales) to Beachport (South Australia), including Victoria, Bass Strait and Tasmania (Last and Stevens 1994). Large estuaries, such as the Derwent River are important for pupping in Tasmania (Last 2002).|
Native:Australia (New South Wales, South Australia, Tasmania, Victoria)
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No information is available, although this is an abundant urolophid.|
|Habitat and Ecology:||
Found on the continental shelf on soft bottoms but exhibiting different habitat preferences in the north and the south of its range. In Tasmania found on shallow muddy bottoms in very shallow waters and in Victoria rarely seen in waters less than 25 m, probably more common >100 m depth. Recorded to 160 m by Last and Stevens (1994), but also occurs onto the upper continental slope as documented by Graham et al. (2001). Little is known of the species' biology, but is aplacental viviparous and likely to have low fecundity (1 to 2 young/year) as with other urolophid species (for example, see White et al. 2001). Both sexes mature at 6 years of age and maximum age is at least 11 years (Treloar and Laurenson in press).
Diet is dominated by isopods and polychaetes (Treloar and Laurenson in press). Life history parameters from Treloar and Laurenson (in press), unless otherwise stated.
Life history parameters
Age at maturity : 6 years (both male and female).
Size at maturity (total length): 30 cm TL (Trinnie 2003), 32 cm TL (female); 25 cm TL (Last and Stevens 1994), 24 cm TL (Trinnie 2003) (male).
Longevity: At least 9 years.
Maximum size (total length): 50 cm TL (Last and Stevens 1994).
Size at birth: 10 to 11cm TL.
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.
This species is taken as a bycatch in the Southern and Eastern Scalefish and Shark Fishery (SESSF) by otter trawl and gillnet. However, its "catch susceptibility" to trawling, gillnet and indeed all gear types used in the fishery is considered to be low (catch susceptibility is defined as "availability" x "encounterability" x "selectivity" x "post-capture mortality"; Walker 2004). The species actually has a high "encounterability" and "selectivity" and a medium "post-capture mortality" to otter trawl gear in the fishery, however its "availability" is low as it is mostly distributed outside trawling effort. In contrast its "availability" to gillnet is high, but "encounterability" and "selectivity" are low (Walker 2004).
Urolophus cruciatus was documented in fishery-independent trawl surveys comparing the bycatch of chondrichthyans between 1976-77 and 1996-97 off the New South Wales upper slope documented an overall decline in the catch rate of urolophids of 65.6% (Graham et al. 2001). Urolophus bucculentus and U. viridis were the commonly caught species, while U. sufflavus and U. cruciatus were taken in smaller quantities. Urolophus cruciatus was taken off Ulladulla and Eden trawl grounds where the urolophid catch rate declined by 81.2% and 90.5%, respectively (Graham et al. 2001). These areas represent only the northern most part of the species' range and the species remains common across the majority of its range.
The lack of trawling in Bass Strait and off the west coast of Tasmania benefits this species.
Survivorship is likely to be low if taken at depth in the northern part of the species' range. Furthermore, gravid female urolophids are renowned for aborting embryos upon handling and capture.
Continued monitoring of bycatch in the Southern and Eastern Scalefish and Shark Fishery. No information seems to be available on bycatch in Tasmanian State fisheries (for example the Tasmanian Commercial Scalefish Fishery) and an effort needs to be made to investigate bycatch levels of this and all chondrichthyan species in these fisheries. Similarly, the level of interaction with recreational fishers around Tasmania needs to be determined, although this is probably limited.
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:||Treloar , M.A. 2006. Urolophus cruciatus. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 21 October 2014.|
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