|Scientific Name:||Hydrolagus lemures|
|Species Authority:||(Whitley, 1939)|
Phasmichthys lemures Whitley, 1939
|Taxonomic Source(s):||Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds). 2016. Catalog of Fishes: genera, species, references. Updated 31 March 2016. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 31 March 2016).|
|Taxonomic Notes:||Hydrolagus lemures is very similar to Hydrolagus ogilbyi, in fact the two species are nearly indistinguishable. Juveniles and subadults are particularly difficult to distinguish and H. lemures is likely often misidentified as H. ogilbyi. This species may exhibit colour variation throughout its range, making it even more challenging to distinguish this species from the very similar H. ogilbyi. It is possible H. lemures is in fact a synonym of H. ogilbyi; however, according to Last and Stevens (1994), H. lemures appears to be more widespread and occurring in deeper water than H. ogilbyi. Research on taxonomic distinction between these two species is ongoing and until conclusive evidence is presented to the contrary, H. lemures and H. ogilbyi are valid as separate species.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Dagit, D.D., Kyne, P.M. & Rigby, C.L.|
|Reviewer(s):||Lawson, J. & Dulvy, N.K.|
|Facilitator/Compiler(s):||Kyne, P.M., Walls, R.H.L., Simpfendorfer, C. & Chin, A.|
The Blackfin Ghostshark (Hydrolagus lemures) is a relatively small-bodied holocephalan species, very similar and sometimes nearly indistinguishable from Ogilby's Ghostshark (H. ogilbyi), with which its range overlaps. It is endemic to Australia and widespread throughout its range from northern Queensland to Western Australia. A shelf and upper slope dweller, this species is reported from depths of 160-825 m but is most common at 200-510 m.
It is apparently relatively abundant in parts of its range, but confirmation of taxonomic distinction between the Blackfin Ghostshark and Ogilby's Ghostshark is needed to better define distribution. Fishery independent surveys on the New South Wales upper slope have documented significant declines (of 96.4% overall and >99% in some regions) in the catch rate of 'silver ghostsharks' over a 20 year period as a result of intensive trawl fishing on the narrow New South Wales continental slope. The 'silver ghostsharks' were documented as mostly Ogilby's Ghostshark, but were likely to have included some Blackfin Ghostshark. This New South Wales area represents only a proportion of the range of this species and while other trawl fisheries operate in the range of the Blackfin Ghostshark, effort is low in the western part of its range, in the Great Australian Bight and in the vast majority of the species' range off Queensland. Therefore, the species is assessed as Least Concern, although catch levels should continue to be monitored as localised depletions are possible where trawl fishing pressure is high in southeastern Australia.
|Previously published Red List assessments:|
|Range Description:||The Blackfin Ghostshark is endemic to Australia and is widespread on the Australian continental slope, with a nearly continuous distribution from Cairns in Queensland, south to New South Wales, Victoria, Tasmania, South Australia, and north to Scott Reef in Western Australia (Last and Stevens 2009). It is not known from the most northern coasts of Australia, but has been reported from off Darwin (G. Johnson, NT Fisheries, pers. comm. February 2015).|
Native:Australia (New South Wales, Northern Territory, Queensland, South Australia, Tasmania, Victoria, Western Australia)
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – western central; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The species is apparently relatively common throughout its range. Nothing is known of its population size, structure or trajectory, but this species is likely represented by a single population across Australia.|
Significant declines in the catch of 'silver ghostsharks' from 1976-77 to 1996-97 from the upper slope trawl fishery off New South Wales have been documented by fishery independent surveys (Graham et al. 2001). Graham et al. (2001) stated that 'silver ghostsharks' were identified as Ogilby's Ghostshark (Hydrolagus ogilbyi). Sampling for this study occurred in 200-605 m and so it is likely both Ogilby's Ghostshark (which occurs at 40-524 m) and Blackfin Ghostshark (which occurs at 160-825 m) were captured, however upon sample re-examination the bulk of catches did indeed appear to be Ogilby's Ghostshark (K. Graham, The Australian Museum, pers. comm. 2003). The aggregated data does not allow species-specific declines to be elucidated, however, overall 'silver ghostshark' declined from a mean catch rate of 8.3 kg/hour to 0.3 kg/hour in the 20 year period, equating to a decline of >99.9% over three generations (~56 years). Reductions are even more striking when data are broken down into regions, with the mean catch rate off Eden-Gabo Island (northern New South Wales/southern Victoria) declining from 17.4 kg/hour in 1976-77 to <0.1 kg/hour in 1996-97, equating to a decline of >99.9% over three generations (~56 years). Even if these catches are mostly Ogilby's Ghostshark, these data do indicate the vulnerability of Hydrolagus species, including the Blackfin Ghostshark, to trawl operations, showing that large declines from heavy fishing pressure are possible. The relatively narrow continental slope off northern/central NSW, including most of the depth range of Blackfin Ghostshark, is intensively fished and there would be continued pressure on Hydrolagusspecies in this area. More recently, however, standardized catch-per-unit-effort by depth exhibited no trend for either Blackfin Ghostshark or Ogilby's Ghostshark between 1994-2006 (Walker and Gason 2007). This suggests that the population may have stabilized at low levels due to changes in fisheries management.
|Current Population Trend:||Stable|
|Habitat and Ecology:||The Blackfin Ghostshark is a continental shelf and upper slope dweller, occurring at or near the bottom. It is reported from depths of 160 to 825 m but most common at 200-510 m (Kyne 2008, Last and Stevens 2009). It attains at least 82 cm (without the caudal filament; C. Rigby, unpubl. data) and 100 cm total length with the filament. Males mature at about 50 cm (without filament) and female size at maturity is unknown, however mature females have been reported at 72 cm (without filament; Kyne 2008, C. Rigby unpubl. data). A generation length of 18.6 years can be estimated from the Rabbitfish (Chimaera monstrosa), which reaches a similar maximum size (Calis et al. 2005). Little else is known of the biology and habits.|
|Generation Length (years):||18.6|
|Use and Trade:||The flesh of the Blackfin Ghostshark is of high quality although there is no information on the use of this species for human consumption.|
A number of demersal fisheries operate in this species' area of occurrence and this species is likely taken as bycatch in these fisheries, however limited information is available on bycatch levels. Within the Southern and Eastern Scalefish and Shark Fishery (SESSF), the Blackfin Ghostshark is considered to have a high catch susceptibility to otter trawl, a medium catch susceptibility to auto hook gear and a low susceptibility to shark gillnet, shark hook and trap/pot gear (catch susceptibility is defined as 'availability' x 'encounterability' x 'selectivity' x 'post-capture mortality'; Walker et al. 2008).
Some fisheries operating with the species' range have relatively low effort, including the Western Deepwater Trawl Fishery (WDWTF), the North West Slope Trawl Fishery (NWSTF) and the Great Australian Bight Trawl Sector (GABTS) of the SESSF. The WDWTF and NWSTF are managed by limited entry with only 11 and seven fishing permits respectively issued on a five yearly basis (DEH 2004). There is limited bycatch information (DEH 2004), although logbook data from the late 1990s indicate a small catch of 200 kg of ghostshark (Rose and McLoughlin 2001) that could be a number of species that includes the Blackfin Ghostshark. The distribution of trawling in the GABTS is across a very small area with most of the effort in the fishery concentrated on the upper continental shelf and slope, in depths ranging from 100 to 400 metres (AFMA 2014). It is managed by limited entry with 10 fishing concessions and the overall effort is low (Lynch and Garvey 2003). An Ecological Risk Assessment of the Fishery identified the Blackfin Ghostshark as at low risk in the fishery (AFMA 2008). Improved information on the catches of this species in the GABTS should be available in the future as the 2014-2016 Bycatch and Discarding Working Plan for this fishery states that Integrated Scientific Monitoring Program is to include reporting of chondrichthyan catches at species level to enable a time series of catch to be constructed (AFMA 2014).
Observer and fishery independent surveys have shown the species to be a bycatch in the Queensland East Coast Trawl Fishery (deepwater component of the eastern king prawn sector). This sector does not generally operate beyond 200 m depth and so is at the upper limit of the depth range of the Blackfin Ghostshark, although when caught the mortality rate was high (Kyne 2008, C. Rigby, unpubl. data). Outside of this fishery, there is very little other fishing pressure over the species' geographical and bathymetrical depth range off Queensland.
|Conservation Actions:||There are no known conservation measures specific to this species. Detailed comparative study of Blackfin Ghostshark and Ogilby's Ghostshark is recommended to verify the morphological distinction between these two species. Further study of life history characteristics as well as geographic and depth range parameters is also recommended. A continued effort should be made to gain bycatch information in fisheries within the range of this species.|
|Citation:||Dagit, D.D., Kyne, P.M. & Rigby, C.L. 2016. Hydrolagus lemures. The IUCN Red List of Threatened Species 2016: e.T60192A68629739.Downloaded on 18 August 2017.|
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