|Scientific Name:||Squalus mitsukurii|
|Species Authority:||Jordan & Snyder, 1903|
|Taxonomic Notes:||Recent revision of the genus in the Indo-Australian region resulted in the resurrection of S. montalbani (Philippines, Indonesia, Australia) and S. griffini (New Zealand) and the description of S. chloroculus Last, White and Motomura, 2007. These species were previously considered to be con-specific with S. mitsukurii. Further investigation of Squalus mitsukurii from around the world will likely result in more taxa being recognized. For example, references to S. mitsukurii in the Southwest Atlantic and Southeast Pacific likely constitute as yet undescribed species (i.e., Squalus sp. B by Soto (2001)).|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Cavanagh, R.D., Lisney, T.J. & White, W.|
|Reviewer(s):||McAuley, R., Fowler, S., Graham, K. & Valenti, S.V. (Shark Red List Authority)|
The distribution of Shortspine Spurdog (Squalus mitsukurii) is only approximately known and recent revision of the genus in the Indo-Australian region resulted in the resurrection of two species and a new description, previously considered con-specific with S. mitsukurii. Further investigation from around the world will likely result in more taxa being recognized. Due to taxonomic uncertainty (and lack of quantitative data from elsewhere), this species is currently Data Deficient globally. However, deepwater demersal trawl fisheries are expanding in other parts of its possible range, and with the observed declines in similar species where they are heavily fished, together with the knowledge that its biology is similar to other deepwater shark species, S. mitsukurii is not sufficiently fecund to withstand continued exploitation pressure.
|Range Description:||Distribution of this species is only approximately known because of widespread nominal records of Squalus fernandinus and S. blainville that may be based on this species or a species complex, erroneous identifications of this species as S. acanthias in the Western North Pacific and S. cubensis in the Western North Atlantic, as well as sporadic sampling in deep-water localities where S. mitsukurii-like sharks are common (Compagno in prep.). Taxonomic revision of the genus in the Indo-Australian region has resulted in the resurrection and description of new species, previously considered con-specific with S. mitsukurii and further investigation from around the world will likely result in more taxa being recognized.|
Native:Angola (Angola); Argentina; Benin; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cameroon; Chile; China; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Curaçao; Dominican Republic; Equatorial Guinea; France; Gabon; Gambia; Ghana; Gibraltar; Guinea; Guinea-Bissau; Honduras; India; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Liberia; Madagascar; Martinique; Mauritania; Morocco; Mozambique; Namibia; New Caledonia; Nicaragua; Nigeria; Panama; Philippines; Portugal; Saint Kitts and Nevis; Saint Martin (French part); Senegal; Sierra Leone; Sint Maarten (Dutch part); South Africa; Spain (Canary Is.); Taiwan, Province of China; Tanzania, United Republic of; Togo; United States (Florida, Hawaiian Is., Louisiana, North Carolina, Texas); Viet Nam; Western Sahara
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northwest; Atlantic – southeast; Atlantic – southwest; Atlantic – western central; Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Population size is unknown. The species is common to abundant where it occurs, often in large aggregations or schools.|
|Habitat and Ecology:||Found in cold-temperate to tropical seas, near or on the bottom on the continental and insular shelves and upper slopes and on submarine ridges and seamounts at depths of 4 to 954 m, mostly between 100 and 700 m. The wide ranges for the data on biological characteristics available for S. mitsukurii strongly suggests a mix of data from a number of species or at least isolated breeding populations. There are considerable differences in size at maturity and in size differences between adult males and females in populations of nominal S. mitsukurii in different localities, as well as considerable variation within presumed populations. Those off Choshi, Japan are large, with males maturing at 68-80 cm total length (TL) and females at 96-100 cm TL (Taniuchi and Tachikawa 1999, Compagno in prep). Across all populations, the gestation period may be up to two years. Maximum ages recorded from counting bands on dorsal fin spines (assuming annual bands) were 18 years (males) and 27 years (females) (Wilson and Seki 1984, Compagno in prep). It reaches a maximum TL of about 125 cm (females) and at least 96cm (males) and size at birth is about 21-30 cm TL (Compagno in prep).|
This species is apparently commonly caught in demersal fisheries throughout much of its range.
Catches of this dogfish on Hancock Seamount in the Western North Pacific declined dramatically between 1985 and 1988 to 20% of the initial catch during research sampling conducted by the U.S. National Marine Fisheries Service, suggesting extreme vulnerability of small seamount populations of this dogfish to overfishing, compounding their biological vulnerability (Wilson and Seki 1994).
Further research into threats and population trends around the world is required.
There are currently no conservation measures in place for this species.
Taxonomic revision of Squalus mitsukurii is required and further research into threats and population trends of these sharks from around the world is needed to develop separate assessments for the different populations, which may prove to be taxonomically distinct from one another.
|Citation:||Cavanagh, R.D., Lisney, T.J. & White, W. 2007. Squalus mitsukurii. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 30 August 2015.|
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