|Scientific Name:||Hydrolagus homonycteris|
|Species Authority:||Didier, 2008|
|Taxonomic Notes:||Last and Stevens (1994) recorded this species as Hydrolagus sp. A, but it has since been formally described by Didier (2008). The Black Ghostshark (Hydrolagus homonycteris) is probably closely related to Abyssal Ghostshark (H. trolli), but the two differ in that the Black Ghostshark has a longer dorsal spine, smaller claspers and is darker in colour.|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Theiss, S.M., Huveneers, C. & Ebert, D.A.|
|Reviewer(s):||Carlson, J. & Dulvy, N.|
The Black Ghostshark (Hydrolagus homonycteris) occurs along the continental slope and seamounts off the southern coast of Australia, including the waters surrounding Tasmania, at depths of 870–1,450 m. This species is also known from New Zealand waters in depths of 500–1,400 m. Little is known of the biology of this species but like other members of this family, the Black Ghostshark is oviparous. Due to an overlap in habitat, depth and range, this species is at threat as bycatch from benthic deepwater commercial trawl fisheries off both the southern coast of Australia and off New Zealand. The Black Ghostshark was once commonly caught in fisheries targeting Orange Roughy off Tasmania, but this fishery has since been closed. The flesh is of good quality and may have been marketed locally. Detailed information regarding the biology, ecology and life history of this species, as well as regular monitoring of commercial fishery bycatch, is required for effective management and conservation of the species. There is currently insufficient information on the population size/structure, trend and catches for this species to assess it beyond Data Deficient.
|Range Description:||The Black Ghostshark occurs off the southern coast of Australia from Portland, Victoria (ca. 38°53'S, 141°56'E) to Ulladulla, New South Wales (ca. 35°21'S, 150°28'E), including the waters surrounding Tasmania and its southern seamounts (Didier 2008, Last and Stevens 2009). This species is also known from deepwater commercial fishing areas off New Zealand and is most likely widespread throughout the deep waters of New Zealand (Didier 2008).|
Native:Australia (New South Wales, Tasmania, Victoria); New Zealand (North Is., South Is.)
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Pacific – southwest
|Lower depth limit (metres):||1450|
|Upper depth limit (metres):||500|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The Black Ghostshark is apparently common (Last and Stevens 2009), however there are no details on population size, structure or trends.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||
The Black Ghostshark is found along the continental slope and seamounts off Australia at depths of 870–1,450 m, and has been reported from depths of 500–1,400 m in New Zealand waters (Didier 2008, Walker et al. 2008, Last and Stevens 2009). There are no specific details on habitat.
There is little information available on the biology of this species. The Black Ghostshark reaches a maximum total length (TL), including the caudal filament, of at least 108 cm and 66 cm body length (BDL), with males maturing at about 55 cm BDL and females around 60 cm BDL (Didier 2008). Like other members of this family, the Black Ghostshark is oviparous (unpublished data reported in Walker et al. 2008) but size-at-birth is unknown. The diet of this species appears to consist primarily of benthic, shelled invertebrates (e.g. crustaceans and molluscs) and teleost fishes (unpublished data reported in Walker et al. 2008).
|Use and Trade:||
The flesh of the Black Ghostshark is of good edible quality. It was at one time commonly taken by commercial trawlers targeting Orange Roughy (Hoplostethus atlanticus) in the waters surrounding Tasmania, but is not currently retained (Last and Stevens 2009). This species is also documented from deepwater fisheries off New Zealand but information regarding potential utilization in this country is not available.
The Black Ghostshark is not commercially targeted, however the major threat to this species is as bycatch in benthic deepwater trawls in both Australian and New Zealand waters. It was once commonly caught as bycatch in trawl fisheries targeting Orange Roughy off Tasmania (Last and Stevens 2009), most probably in the South Tasman Rise Fishery (STRF). This species has also been reported as (rare) bycatch from the Southern and Eastern Scalefish and Shark Fishery (SESSF) (Walker et al. 2008). The current closure of the STRF, and SESSF restrictions on trawling below 750 m (Wilson et al. 2010) provide some deepwater refuge for the Black Ghostshark.
Information regarding New Zealand fisheries bycatch is scarce, but the Black Ghostshark has been recorded from deepwater commercial fishing grounds at locations such as the Chatham Rise and Lord Howe Rise (Didier 2008).
No conservation actions are currently in place for this species and information regarding the biology of the Black Ghostshark is urgently required. There is no regular monitoring of bycatch in commercial fisheries and so catch and trend information, which is vital to inform management, are lacking. It is recommended that this species be monitored with regard to deepwater fisheries that might target this species for human consumption in the future. Restrictions on trawling below 750 m in the SESSF and the closure of the STRF has in effect provided a deepwater refuge for this species.
|Citation:||Theiss, S.M., Huveneers, C. & Ebert, D.A. 2011. Hydrolagus homonycteris. The IUCN Red List of Threatened Species 2011: e.T195433A8965964. http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T195433A8965964.en . Downloaded on 07 October 2015.|
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