|Scientific Name:||Hydrolagus purpurescens (Gilbert, 1905)|
Chimaera purpurescens Gilbert, 1905
Hydrolagus eidolon (Jordan & Hubbs, 1925)
|Taxonomic Source(s):||Eschmeyer, W.N. and Fricke, R. (eds). 2015. Catalog of Fishes: genera, species, references. Updated 1 October 2015. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 1 October 2015).|
|Taxonomic Notes:||This species is part of a complex of giant black or purple-black species of Hydrolagus, which includes H. affinis and all "affinis-like" species from Australia and New Zealand, South Africa and the southern Atlantic, and the Davison Seamount in the Eastern Central Pacific. The giant black Hydrolagus from the Atlantic is likely Hydrolagus affinis; however, the giant black or purple-black species of Hydrolagus from the Pacific may represent at least two separate species, one of which may be H. purpurescens (Gilbert 1905).|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Machura, B., van Hees, K. & Ebert, D.A.|
|Reviewer(s):||Kemper, J. & Chiquillo, K.L.C|
|Facilitator/Compiler(s):||Lawson, J., Walls, R.H.L. & Dulvy, N.K.|
Purple Chimaera (Hydrolagus purpurescens) is a poorly-known deepwater species that is one of a complex of giant chimaeras that includes Smalleyed Rabbitfish (H. affinis) and other large black or purple-black Hydrolagus species. The species is benthopelagic, and is typically found at depths of 920-1,130 m, with a known range in the Northwest Pacific off Japan from Hokkaido to the Okinawa Trough. The type specimen was recorded off Hawaii, and this species is possibly also found in the waters off Sakhalin, Russia and on the Davidson Seamount off California, USA. This species may actually be more widespread throughout the Pacific, and may be found at greater depths.
At present this species is not known to be commercially targeted or utilized, but it is probably captured as unreported bycatch in deepwater fisheries. Very little is known about its biology, however it is probably a slow-growing species with low fecundity. It faces a potential threat if deepwater fisheries expand, as it could be caught both as bycatch and possibly as a target species.
More data are needed with regard to possible bycatch, life history and geographic range. It is therefore assessed as Data Deficient with the recommendation that the species be reassessed when these data become available.
|Previously published Red List assessments:|
At present, Purple Chimera is known from the northwest Pacific Ocean off Japan. It is known from deep seamounts and troughs off Japan from Hokkaido and the Okhotsk Sea to the Okinawa Trough, although it may be more widespread in deep waters throughout the Pacific (Nakaya 1983, Kyne and Simpfendorfer 2007). The type specimen was recorded from Hawaii, which was the first record outside of Japan (Chave and Mundy 1994), and more recently this species was reportedly captured off the southeastern coast of Sakhalin, Russia (Poltev and Sheiko 2007). Additionally, recent submersible observations of a large, purplish species from the northeastern Pacific (Davidson Seamount) may be Purple Chimera, meaning that it is more widespread throughout the Pacific, however these observations are unconfirmed.
Native:Japan; United States (Hawaiian Is.)
|FAO Marine Fishing Areas:|
Pacific – northwest; Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species may be widespread throughout the Pacific and may be represented by more than one distinct population. Nothing is known of its population size or structure.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Hydrolagus purpurescens is a benthopelagic species that inhabits the upper to middle slope and deep seamounts and troughs at depths of 120 to 1,430 m (Nakaya and Shirai 1992). The type specimen, recorded from Hawaii, was collected from a depth of 1,750-1,951 m.|
Purple Chimera is oviparous, and very little is known of its reproductive biology. Like other large, deepwater chimaeroids, this may be a slow-growing species with low fecundity. Its size at maturity is estimated to be ~100 cm total length (TL). A single male specimen was found to be 122 cm TL and 6.9 kg (Poltev and Sheiko 2007). The maximum observed size is 138 cm TL, but this species probably reaches ~150 cm TL.
|Use and Trade:||This species is not utilized.|
|Major Threat(s):||Purple Chimera may obtained as bycatch in deepwater commercial trawl and longline fisheries. It is not known to be caught in any numbers at present. The mean depth of fishing has increased by 62.5 m per decade, leading to an overall increase of 350 m since 1950 (Watson and Morato 2013). If deepwater fisheries continue to expand, there is the possibility that this large species may start to be either targeted or retained as bycatch.|
No management or conservation measures are known to be in place for this species. It is recommended that data on life history characteristics be collected from all captured specimens. Collection of voucher specimens from the Davidson Seamount, as well as collection and study of specimens of all large purple and purple-black Hydrolagus spp. specimens from the Pacific, will be important for determining whether the known range of Purple Chimaera does indeed extend throughout the Pacific.
The development and implementation of management plans [national and/or regional; e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks)] are required to facilitate the conservation and management of all chondrichthyan species in the regions where this species occurs.
|Citation:||Machura, B., van Hees, K. & Ebert, D.A. 2015. Hydrolagus purpurescens. The IUCN Red List of Threatened Species 2015: e.T60196A80804439.Downloaded on 13 December 2017.|
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