Tetronarce tokionis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rajiformes Torpedinidae

Scientific Name: Tetronarce tokionis (Tanaka, 1908)
Common Name(s):
English Longtail Torpedo Ray
Tetronarcine tokionis Tanaka, 1908
Torpedo tokionis (Tanaka, 1908)
Taxonomic Source(s): Eschmeyer, W.N. (ed.). 2015. Catalog of Fishes. Updated 3 August 2015. Available at: (Accessed: 3 August 2015).
Taxonomic Notes: The Australian form of Tetronarce tokionis is provisionally considered to be same species as that occurring off Japan and Taiwan (Last and Stevens 2009). Around Taiwan, the species has been confused with T. formosa Haas & Ebert, 2006.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2016
Date Assessed: 2015-05-17
Assessor(s): Haas, D.L., Ebert, D.A., Nakaya, K., Tanaka, S., Orlov, A., Sherman, C.S. & Kyne, P.M.
Reviewer(s): Walls, R.H.L. & Bigman, J.S.
Contributor(s): Bigman, J.S.
Facilitator/Compiler(s): Kyne, P.M. & Walls, R.H.L.
The Longtail Torpedo Ray (Tetronarce tokionis) is a poorly known, uncommon electric ray, distributed in Northwest Pacific waters of Japan and Taiwan and off the east and west coasts of Australia. It has been recorded in trawl surveys at depths of 220–1,100 m in Japan, and at depths of 410–735 in Australia. The Australian form is provisionally recognized as the same as that occurring in the Northwest Pacific, but the species' true distribution is uncertain. In the Northwest Pacific, this species is an occasional bycatch of trawl and gillnet fisheries and is sometimes seen in fish markets; it is used for fishmeal or is discarded. This species may have some refuge from fishing pressure at the deeper extent of its depth range in Japan and Taiwan. In Australia, this torpedo ray has very little overlap with trawl fisheries and likely receives refuge outside of fished areas. However, taxonomic resolution is required to compare the Northwest Pacific and Australian forms, and therefore the species is assessed as Data Deficient until its taxonomy and distribution are better understood.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Longtail Torpedo Ray has a patchy known distribution in the Indo-West Pacific. In the Northwest Pacific, it occurs from the coast of Tohoku District, Japan, southward to the East China Sea, Ryukyu Islands, and Taiwan (Nakabo 2002, Ebert et al. 2013, 2014, D.A. Ebert, unpubl. data). In Australian waters, it is found on the continental slope off eastern Australia between Bowen (Queensland) and Newcastle (New South Wales), and on the west coast from Shark Bay to Rowley Shoals (Western Australia) (Last and Stevens 2009). It is possibly also found in New Zealand (Last and Stevens 2009).
Countries occurrence:
Australia (New South Wales, Queensland, Western Australia); Japan; Taiwan, Province of China
FAO Marine Fishing Areas:
Indian Ocean – eastern; Pacific – northwest; Pacific – southwest; Pacific – western central
Additional data:
Lower depth limit (metres):1100
Upper depth limit (metres):220
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Little is know about the population of this species, but it seems to be uncommon. Very few specimens were caught in an experimental otter trawl fisheries investigation, which was conducted in the 1980s and 1990s in the Northwest Pacific. The species was captured in trawls from 220 m deep in Okinawa Trough, East China Sea, and 1,100 m deep from the Tohoku slope off northern Japan (Nakaya and Shirai 1992). It is occasionally seen in fish markets in northeast Taiwan (Ebert et al. 2013). Little is known about the population size in Australia, where it is thought to be rare.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:The Longtail Torpedo Ray is a little known species found on stone, sand, or mud habitats at depths of 220–1,100 m (Nakaya and Shirai 1992). It may be more semi-pelagic rather than demersal. In Australia, it is found in waters 410–735 m deep (Last and Stevens 2009). Members of the family Torpedinidae exhibit lecithotrophic viviparity. Maximum size on record for this species is 69.3 cm total length (TL) in Japan and Taiwan (Haas and Ebert 2006, Last and Stevens 2009, Ebert et al. 2013) and 34 cm TL in Australia (Last and Stevens 2009).

Use and Trade [top]

Use and Trade: The meat is of poor quality and so it is often discarded or used for fishmeal (D. Ebert, pers. obs., 2007-2015).

Threats [top]

Major Threat(s): This species is occasionally caught as bycatch in bottom trawl and gillnet fisheries off Japan and Taiwan. It has been observed in fish markets in Tokyo, Japan, and Tachi, Taiwan (Ebert et al. 2013). In Taiwan, it is only known from fish markets where it is occasionally seen (usually one or two a day) (D. Ebert, pers. obs., 2007-2015). The electric discharge emitted by this species makes it unpleasant to handle and the meat is of poor quality. It is often discarded or used for fishmeal (D. Ebert pers. obs., 2007-2015).

There is relatively low fishing effort in the geographic and depth range of the species where it occurs in Australia. On the east coast, the species occurs north of the Commonwealth Trawl Sector of the Southern and Eastern Scalefish and Shark Fishery (Penney et al. 2014), but its range does overlap with the Coral Sea Fishery. This is a relatively small-scale fishery with no trawl effort since the 2006-07 fishing season (Noriega et al. 2014). Trawling in the past within this fishery has been low effort, and while it is possible that this torpedo ray was a bycatch of trawling, the management area of the fishery is far greater than the range of this species, with the majority of fishing effort outside of its area of occurrence. Other sectors of the fishery use gear unlikely to interact with batoids. Similarly, off the west coast, the Western Deepwater Trawl Fishery and the Northwest Slope Trawl Fishery are very low effort (Marton and Mazur 2014a, 2014b) and are not likely to regularly interact with the Longtail Torpedo Ray.

Conservation Actions [top]

Conservation Actions: There are no conservation measures in place for this species. Assessment and monitoring of catches and population trends is needed, as well as research on its life history characteristics.

Citation: Haas, D.L., Ebert, D.A., Nakaya, K., Tanaka, S., Orlov, A., Sherman, C.S. & Kyne, P.M. 2016. Tetronarce tokionis. The IUCN Red List of Threatened Species 2016: e.T161676A70710022. . Downloaded on 22 June 2018.
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