|Scientific Name:||Hydrolagus purpurescens|
|Species Authority:||(Gilbert, 1905)|
Hydrolagus eidolon (Jordan & Hubbs, 1925)
|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.|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Reviewer(s):||Kyne, P.M., Fowler, S.L. & Compagno, L.J.V. (Shark Red List Authority)|
Hydrolagus purpurescens is a poorly known deepwater species that is one of a complex of giant chimaeras (e.g., H. affinis). Benthopelagic, typically found at depths of 920 to 1,130 m with a known range in the Northwest Pacific off Japan from Hokkaido to the Okinawa Trough. The only record outside of Japan is the type specimen recorded from Hawaii at a depth of 1,750 to 1,951 m. This species may actually be more widespread throughout the Pacific, and at greater depths. At least some of the large, purplish Hydrolagus recently captured and observed from the southwestern and eastern Pacific may prove to be H. purpurescens, thus confirming a widespread distribution for this species in the Pacific. At present this species is not known to be commercially targeted or utilised, but is probably captured as unreported bycatch in deepwater fisheries. Very little is known of the biology of this species, however, it is probably a slow-growing species with low fecundity. It faces a potential threat due to expanding deepwater fisheries, both as bycatch and possibly as a target resulting from the collapse of more lucrative fisheries. More data are needed with regard to bycatch, life history and geographic range. It is recommended the assessment of Data Deficient be reevaluated when these data become available.
|Range Description:||At present known from deep seamounts and troughs off Japan from Hokkaido and the Okhotsk Sea to the Okinawa Trough, although may be more widespread in deep waters throughout the Pacific. The type specimen from Hawaii is the only record of H. purpurescens outside of Japan.
Recent submersible observations of a large purplish species from the eastern Pacific (Davison Seamount) have not conclusively been referred to this species; however, it is possible that H. purpurescens is more widespread throughout the Pacific.
Native:Japan; United States (Hawaiian Is.)
|FAO Marine Fishing Areas:||
Pacific – eastern central; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||May be widespread throughout the Pacific and represented by more than one distinct population. Nothing is known of population structure.|
|Habitat and Ecology:||
Benthopelagic species that lives on the upper to middle slope and deep seamounts and troughs. Occurs at depths of 920 to 1,130 m off Japan, with the type specimen collected from 1,750 to 1,951 m off Hawaii. May be more widespread in deeper waters.
Oviparous, although nothing is known of reproductive biology. Eggs, hatchlings and small juveniles are rarely if ever collected. Diet probably consists of a variety of benthic invertebrates. Like other large chimaeroids, this may be a slow-growing species with low fecundity.
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total/body length): ~100 cm TL (~55 to 60 cm BDL).
Longevity (years): Unknown.
Maximum size (total/body length): 138 cm TL; 89 cm BDL (probably reaches ~150 cm TL).
Size at birth (cm): Unknown.
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.
|Major Threat(s):||Possible threat due to bycatch in deepwater commercial trawl and longline fisheries. Not known to be targeted or caught in any numbers at present, but there is the possibility this large species may be targeted in deepwater fisheries as nearshore fisheries are depleted and deepwater fisheries expand.|
None are known to be in place. It is recommended that data on life history characteristics be collected from all specimens captured. Collection of voucher specimens from the Davison Seamount, as well as collection and study of specimens of all large purple and purple-black Hydrolagus from the Pacific will be important for determining if the known range of Hydrolagus purpurescens does 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:||Dagit, D.D. 2006. Hydrolagus purpurescens. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 31 August 2015.|
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