Pseudotriakis microdon 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Carcharhiniformes Pseudotriakidae

Scientific Name: Pseudotriakis microdon de Brito Capello, 1868
Regional Assessments:
Common Name(s):
English False Catshark, Keel-dorsal Shark
French Requin À Longue Dorsale
Spanish Musolón De Aleta Larga
Pseudotriakis acrales Jordan & Snyder, 1904
Taxonomic Notes: Yano and Musick (1992) showed that morphometric characters used to separate Pacific Pseudotriakis acrales Jordan & Snyder, 1904 from Atlantic P. microdon de Brito Capello, 1868 did not differ significantly, and these authors confirmed P. acrales as a junior synonym of P. microdon. Pseudotriakis is thus a mono-specific genus.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2015-05-13
Assessor(s): Kyne, P.M., Yano , K. & White, W.T.
Reviewer(s): Simpfendorfer, C. & Dulvy, N.K.
Facilitator/Compiler(s): Kyne, P.M. & Walls, R.H.L.
The False Catshark (Pseudotriakis microdon) is a wide-ranging but sporadically captured, large-bodied, deepwater shark with most records from the Northern Hemisphere (it appears rarer in the Southern Hemisphere). It may be cosmopolitan, but as yet has not been recorded from the South Atlantic or Eastern Pacific. Primarily inhabits the continental and insular slopes at depths of 100 to 1,890 m, but also occasionally occurs on the continental shelf. The False Catshark reaches a maximum size of 296 cm total length. This species displays a modified form of oophagy, the first confirmed oophagous species outside the Lamniformes. Fecundity is low (two embryos per litter), and this, combined with an estimated long gestation period and presumed slow growth rate may place populations at risk of localised depletion if the species becomes more regularly caught. At present the species is of no interest to fisheries but is taken sporadically as bycatch in deepwater longline and trawl fisheries. Deepwater fisheries are generally expanding globally, and given the biology of this species, bycatch of this uncommon to rare fish may be of concern for any localised populations in areas where fishing may be concentrated, such as deepwater reefs or seamounts. However, the species has a widespread geographic and depth range, and is continuing to be documented in new locations in the deepsea, and is therefore assessed as Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:A wide-ranging species, the full extent of occurrence of the False Catshark is uncertain as records are sporadic. Records from the Southern Hemisphere are relatively scarce and the species most likely occurs at more locations than presently recorded (as evidenced by recent new records e.g. Friedlander et al. 2014, Brooks et al. 2015).

Northwest Atlantic (Canada, New York to New Jersey); Western Central Atlantic (The Bahamas); Northeast and Eastern Central Atlantic (Atlantic Slope off Iceland, France, Portugal, Madeira, Azores, Canary Islands, Senegal and Cape Verde Island); Western Indian Ocean (Aldabra Island group) and locations in the Southwest Indian (Alastair Graham, pers. comm., 2004); Northwest Pacific (Japan (southern Honshu and Okinawa) and Taiwan); Eastern Indian Ocean (Australia (Cape Leeuwin, Western Australia), eastern Indonesia); Western Central Pacific (Coral Sea, off Mackay, Queensland); Southwest Pacific (New Zealand (Three Kings Ridge and Hikurangi Trough, east of Mahia Peninsula), Pitcairn Islands); and Central Pacific (Hawaiian Islands) (Stewart and Clark 1988, Yano 1992, Yano and Musick 1992, Allen and Cowan 1995, Gilhen and Coad 1999, Stewart 2000, Baranes 2003, Kyne et al. 2005, King et al. 2006, Ebert et al. 2013, Friedlander et al. 2014, Brooks et al. 2015).
Countries occurrence:
Australia (Queensland, Western Australia); Bahamas; Canada; Cape Verde; France; Iceland; Indonesia; Japan (Honshu); New Zealand; Pitcairn; Portugal (Azores, Madeira); Senegal; Seychelles (Aldabra); Spain (Canary Is.); Taiwan, Province of China; United States (Hawaiian Is., New Jersey, New York)
FAO Marine Fishing Areas:
Atlantic – western central; Atlantic – northeast; Atlantic – northwest; Atlantic – eastern central; Indian Ocean – western; Indian Ocean – eastern; Pacific – southwest; Pacific – western central; Pacific – eastern central; Pacific – northwest
Additional data:
Lower depth limit (metres):1890
Upper depth limit (metres):100
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Seemingly uncommon or rare wherever it occurs in its deepwater habitat.
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:The False Catshark is a large deepwater benthic shark recorded from depths of 100 to 1,890 m on the continental and insular slopes, including around seamounts, troughs and deepwater reefs. This species is occasionally recorded on the continental shelves including in shallow water. This may be abnormal behaviour or where submarine canyons extend close to shore. The anatomy of this shark (large body cavity, soft fins, musculature and skin) suggests an inactive and sluggish lifestyle (Ebert et al. 2013).

Maximum size 296 cm total length (TL) (female), 295 cm TL (male) (Yano 1992); males mature at about 260 cm TL, females at about 265 cm TL (Ebert et al. 2013). Taniuchi et al. (1984) observed near-term embryos of 112 and 113 cm TL, and Yano (1992) at 116 to 120 cm TL. A 156 cm TL immature female had an umbilical scar (Yano 1992). Size at birth 120 to 150 cm TL (K. Yano, unpubl. data).

Forster et al. (1970) suggested that the False Catshark was oophagous based on the large number of ova (estimated at 20,000) of 9 mm mean diameter observed in the ovary of a 280 cm TL female. Taniuchi et al. (1984) reported mid-term and near-term embryos with stomachs full of yolk. Yano (1992) confirmed the existence of oophagy in this species showing that embryos ingest and utilize yolk material from ovulated ova. Yolk material was observed in the uteri of gravid females and the stomachs of two embryos contained yolk material and egg capsules. Yano (1992) reported that the reproductive mode in this species is a modified form of oophagy in which embryos appear to transfer yolk from ingested egg fragments to their external yolk sac, replenishing external yolk sac reserves and using them in the last stages of gestation. Reported litter size of this species is two (Taniuchi et al. 1984, Yano 1992, Stewart 2000). Gestation period is unknown, but is presumed to be > 1 year and possibly more than 2 or 3 years (K. Yano, unpubl. data).

Use and Trade [top]

Use and Trade: Utilization is not reported in this species.

Threats [top]

Major Threat(s): Localised populations of this large shark could be rapidly depleted if it began to be captured more regularly, however, at present it is of little interest to fisheries and is only taken as sporadic bycatch. Most specimens of this species have been taken on deep-set longlines or in deepwater bottom trawls. Among the specimens reported in the literature as taken from commercial fishing operations, individuals have been captured as bycatch of trawls for Atlantic Halibut (Hippoglossus hippoglossus) in the North Atlantic Ocean (Gilhen and Coad 1999) and Orange Roughy (Hoplostethus atlanticus) in the southern Indian Ocean (Allen and Cowan 1995), and developmental fishing surveys for bottom longline fisheries in the North Pacific Ocean (Yano 1992). The Queensland, Australia specimen was taken by exploratory deepwater dropline fishing targeting deepwater reef fishes, particularly Flame and Ruby Snapper (Etelis spp.) and Bar Cod (Epinephelus spp.) (Kyne et al. 2005).

Conservation Actions [top]

Conservation Actions: None in place. Deep-sea marine protected areas would be important in preserving habitat of this and other deepwater species. It may occur in deeper areas of Australia's Commonwealth Marine Reserve network.

Citation: Kyne, P.M., Yano , K. & White, W.T. 2015. Pseudotriakis microdon. The IUCN Red List of Threatened Species 2015: e.T44566A2995045. . Downloaded on 25 September 2018.
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