|Scientific Name:||Hydrolagus mitsukurii|
|Species Authority:||(Jordan & Snyder, 1904)|
|Taxonomic Notes:||Synonyms = Chimaera deani Smith & Radcliffe, 1912 in Smith, 1912; Chimaera phantasma Jordan & Fowler, 1903 (in part).
Dean (1904) also described this species, but his paper was published three weeks after Jordan and Snyder and was based on different specimens; therefore, the account of Jordan and Snyder is valid for H. mitsukurii and Dean?s is a junior synonym. Hydrolagus deani Smith & Radcliffe, 1912 in Smith, 1912 is a synonym of H. mitsukurii.
|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 mitsukurii is a very poorly known species with a range apparently restricted to parts of the Northwest and Western Central Pacific. Known primarily from Japan, but also reported from the Philippines, Taiwan, Korea and the East China Sea, this species may have a wider range in the North Pacific including the South China Sea and Indonesia. Prefers deep bays and slopes and reported from depths of 325 to 710 m, this species may be more abundant at greater depths. Based on existing specimens and records this species is seemingly rare; however, this may be a reflection of local fishing effort. Although a few egg capsules and small juveniles have been collected, very little is known of the biology of this species, particularly reproductive biology and life history parameters. Probably a single population exists, restricted to the North Pacific. Although not directly targeted, this species is landed and utilised in some fish markets in Taiwan, and possibly elsewhere when captured as bycatch in deepwater fishing activities. Landing of this species in Taiwan appears to be a more recent occurrence, suggesting that fishers are moving into deeper waters, probably as a result of the depletion of shallower water resources. As such, the species may face potential threats due to habitat destruction and/or bycatch fishing should deepwater trawling operations increase in the region. More data and specimens are needed and a reassessment is recommended pending the acquisition of additional data on this species.
|Range Description:||Known primarily from Japan, off Honshu from Sagami and Suruga Bays, also reported from the Philippines, Taiwan, Korea and the East China Sea. Probably also occurs in the South China Sea and off Indonesia and may be relatively widespread throughout the Northwest and North Central Pacific.|
Native:China; Japan (Honshu); Korea, Republic of; Philippines; Taiwan, Province of China
|FAO Marine Fishing Areas:||
Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Apparently a relatively rare species based on capture records; however, this may be due to the fact that most fishing in the region occurs at depths shallower than the preferred depth for this species; hence it is rarely collected rather than actually being rare in terms of actual numbers. Further data will be needed to verify actual abundance of the species. Likely a single population occurring throughout its range.|
|Habitat and Ecology:||
A benthopelagic species occurring in deepwater bays and troughs and on upper to middle slopes. Recorded depth range is 325 to 710 m, but probably occurs in deeper waters. This is a small-bodied species, similar to Hydrolagus mirabilis. Oviparous, very little is known of reproductive biology although a few eggs and small juveniles have been collected. Diet probably consists of a variety of benthic invertebrates.
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total/body length): ~65 to 70 cm TL (~30 to 35 cm BDL) (male & female).
Longevity (years): Unknown.
Maximum size (total/body length): 79 cm TL (37 cm BDL).
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.
Overall, the species is presently considered rare, but more information is needed with regard to capture levels as well as geographic range of this species.
Fairly commonly landed in some fish markets in Taiwan (W. White, pers. comm.) and probably caught as bycatch in deepwater trawls elsewhere (for example in Suruga Bay, Japan). Landing of this species in Taiwan appears to be a more recent occurrence, suggesting that fishers are moving into deeper waters, probably as a result of the depletion of shallower water resources.
Potentially faces threat of habitat destruction and/or capture as bycatch should deepwater fishing efforts increase in the region.
Additional specimens, particularly from parts of the range outside Japan are needed for research. In addition, it is recommended that life history data be collected from all captured specimens.
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 region.
|Citation:||Dagit, D.D. 2006. Hydrolagus mitsukurii. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 12 December 2013.|
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