Pseudotriakis microdon 

Scope: Global
Language: English

Translate page into:

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.

Classifications [top]

11. Marine Deep Benthic -> 11.1. Marine Deep Benthic - Continental Slope/Bathyl Zone (200-4,000m) -> 11.1.1. Hard Substrate
suitability:Suitable season:unknown major importance:Yes
11. Marine Deep Benthic -> 11.1. Marine Deep Benthic - Continental Slope/Bathyl Zone (200-4,000m) -> 11.1.2. Soft Substrate
suitability:Suitable season:unknown major importance:Yes
11. Marine Deep Benthic -> 11.5. Marine Deep Benthic - Seamount
suitability:Suitable season:unknown major importance:Yes

In-Place Research, Monitoring and Planning
  Action Recovery plan:No
  Systematic monitoring scheme:No
In-Place Land/Water Protection and Management
  Conservation sites identified:No
  Occur in at least one PA:Unknown
  Area based regional management plan:No
  Invasive species control or prevention:Not Applicable
In-Place Species Management
  Harvest management plan:No
  Successfully reintroduced or introduced beningly:No
In-Place Education
  Subject to recent education and awareness programmes:No
  Included in international legislation:No
  Subject to any international management/trade controls:No
5. Biological resource use -> 5.4. Fishing & harvesting aquatic resources -> 5.4.4. Unintentional effects: (large scale) [harvest]
♦ timing:Ongoing ♦ scope:Unknown ♦ severity:Unknown ⇒ Impact score:Unknown 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology
1. Research -> 1.5. Threats
3. Monitoring -> 3.1. Population trends

Bibliography [top]

Allen, G.R. and Cowan, M.A. 1995. First record of the false catshark, Pseudotriakis microdon, from Australian seas. Records of the Western Australian Museum 17: 235–236.

Baranes, A. 2003. Sharks from the Amirantes Islands, Seychelles, with a description of two new species of Squaloids from the deep sea. Israel Journal of Zoology 49(1): 33-65.

Brooks, E.J., Brooks, A.M.L., Williams, S., Jordan, L.K.B., Abercrombie, D., Chapman, D.D., Howey-Jordan, L.A. and Grubbs, R.D. 2015. First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas. Deep-Sea Research II 115: 81-91.

Ebert, D.A., Fowler, S. and Compagno, L. 2013. Sharks of the World. A Fully Illustrated Guide. Wild Nature Press, Plymouth, United Kingdom.

Forster, G.R., Badcock, J.R., Longbottom, M.R., Merrett, N.R. and Thomson, K.S. 1970. Results of the Royal Society Indian Ocean Deep Slope Fishing Expedition, 1969. Proceedings of the Royal Society of London Series B 175: 367–404.

Friedlander, A.M., Caselle, J.E., Ballesteros, E., Brown, E.K., Turchik, A. and Sala, E. 2014. The real bounty: marine biodiversity in the Pitcairn Islands. PLoS ONE 9(6): e100142.

Gilhen, J. and Coad, B.W. 1999. The false catshark, Pseudotriakis microdon Capello, 1867, new to the fish fauna of Atlantic Canada. Canadian Field Naturalist 113(3): 514–516.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

IUCN SSC Shark Specialist Group. Specialist Group website. Available at:

King, N.J., Bagley, P.M. and Priede, I.G. 2006. Depth zonation and latitudinal distribution of deep-sea scavenging demersal fishes of the Mid-Atlantic Ridge, 42 to 53°N. Marine Ecology Progress Series 319: 263-274.

Kyne, P.M., Johnson, J.W., White, W.T. and Bennett, M.B. 2005. First records of the false catshark, Pseudotriakis microdon Capello, 1868, from the waters of eastern Australia and Indonesia. Memoirs of the Queensland Museum 51: 525-530.

Last, P.R. and Stevens, J.D. 2009. Sharks and Rays of Australia. Second Edition. CSIRO Publishing, Collingwood.

Stewart, A.L. 2000. False catshark – a real rarity. Seafood New Zealand.

Stewart, A.L. and Clark, M.R. 1988. Records of three families and four species of fish new to the New Zealand fauna. New Zealand Journal of Zoology 15: 577–583.

Taniuchi, T., Kobayashi, H. and Otake, T. 1984. Occurrence and reproductive mode of the false cat shark, Pseudotriakis microdon, in Japan. Japanese Journal of Ichthyology 31(1): 88–92.

Yano, K. 1992. Comments on the reproductive mode of the false cat shark Pseudotriakis microdon. Copeia 1992(2): 460–468.

Yano, K. and Musick, J.A. 1992. Comparison of morphometrics of Atlantic and Pacific specimens of the false catshark, Pseudotriakis microdon, with notes on stomach contents. Copeia 1992(3): 877–886.

Citation: Kyne, P.M., Yano , K. & White, W.T. 2015. Pseudotriakis microdon. The IUCN Red List of Threatened Species 2015: e.T44566A2995045. . Downloaded on 17 August 2018.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided