|Scientific Name:||Tetronarce nobiliana (Bonaparte, 1835)|
Torpedo nobiliana Bonaparte, 1835
|Taxonomic Source(s):||Eschmeyer, W.N. (ed.). 2015. Catalog of Fishes. Updated 3 August 2015. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 3 August 2015).|
|Taxonomic Notes:||The name as allocated to the southern African material is provisional. Work underway suggests that there may be a tropical species from off southern Mozambique that is more similar to true T. nobiliana from the North Atlantic than to specimens from Namibia and the Cape. Work is underway to clarify the taxonomy of the Indian Ocean species.|
|Red List Category & Criteria:||Least Concern (Regional assessment) ver 3.1|
|Assessor(s):||Bradai, M.N. & Ellis, J.R.|
|Reviewer(s):||Serena, F., Kemp, J.R. & Allen, D.J.|
|Contributor(s):||Notarbartolo di Sciara, G., Serena, F., Ungaro, N., Ferretti, F., Holtzhausen, H., Smale, M., Buscher, E. & Fordham, S.|
|Facilitator/Compiler(s):||Walls, R.H.L. & Dulvy, N.K.|
Mediterranean regional assessment: Least Concern (LC)
The Great Torpedo Ray (Tetronarce nobiliana) is a widespread, large (up to 180 cm total length) electric ray. Adults are pelagic and/or semi-pelagic, swimming in the water column at depths of zero to 800 m, whereas juveniles are mainly benthic and live on soft substrate and reef habitat in shallower water. This electric ray is caught incidentally in bottom trawls and line gear in the Mediterranean Sea, and usually discarded at sea, resulting in limited catch data; very little catch data are available from scientific trawl surveys either. Given that this is a widespread pelagic species that is rarely caught in fisheries, the Great Torpedo Ray is assessed as Least Concern in Mediterranean waters. Further research is required to assess the effect of fishing activities on the population and identify important habitats.
|Range Description:||This electric ray is present throughout the continental shelf zone of the Mediterranean Sea (Stehmann and Bürkel 1984, Serena 2005).|
Native:Albania; Algeria; Bosnia and Herzegovina; Croatia; Cyprus; Egypt (Egypt (African part), Sinai); France (Corsica, France (mainland)); Gibraltar; Greece (East Aegean Is., Greece (mainland), Kriti); Israel; Italy (Italy (mainland)); Lebanon; Libya; Montenegro; Morocco; Palestinian Territory, Occupied; Slovenia; Spain (Baleares, Spain (mainland), Spanish North African Territories); Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
|FAO Marine Fishing Areas:|
Mediterranean and Black Sea
Few data are available for inferring population trends for this species across its range. Low frequency of occurrence in bottom trawl surveys from the Mediterranean Sea suggest that it is relatively rare. During the International Bottom Trawl Survey in the Mediterranean (MEDITS), the Great Torpedo Ray was captured in 73 of 6,336 hauls conducted throughout the northern Mediterranean Sea at depths of 10−800 m between 1994 and 1999, and it appears to be more common in the western basin (Baino et al. 2001). In the Gruppo Nazionale Demersali Italian scientific trawl surveys, this species was reported in low numbers from several locations along the Italian coast, including: Sicily, Calabria, Gulf of Taranto, Sardinia, and the northern Tyrrhenian Sea. It is rarely recorded off Tuscany and Corsica (Relini et al. 2000, Ferretti et al. 2005). Historical records report this ray in the northern Tyrrhenian Sea (D’Ancona and Razzauti 1937, Foresi 1986), Ligurian Sea (Ariola 1904, Brunelli and Bini 1934) and Gulf of Lion (Aldebert 1997), but it is difficult to evaluate previous trends in abundance as most of these reports are qualitative and do not specify catch rates for this species.
Despite the lack of data suggesting abundance and population trends, it is suspected that the Mediterranean portion of the population is stable owing to its limited interaction with fisheries and lack of commercial value.
|Current Population Trend:||Stable|
|Habitat and Ecology:|
The Great Torpedo Ray occurs at depths of zero to 800 m. Juveniles are mainly benthic on soft substrates and coral reef habitats at depths of 10−150 m, and sometimes considerably deeper (up to 350 m). Adults may be pelagic or semi-pelagic, solitary, and are reportedly capable of migrating over great distances (Ebert and Stehmann 2013). Specimens were captured in MEDITS surveys throughout the depth range surveyed (10−800 m), but mostly at depths of 200−500 m (Baino et al. 2001).
Embryos of this live-bearing species rely on yolk-only nutrition. Large females reportedly carry up to 60 embryos. The gestation period is ~12 months and size at birth is 20−25 cm total length (TL; Whitehead et al. 1984, McEachran and de Carvalho 2002). The smallest mature male ever reported was 55 cm TL, and the smallest mature female was 90 cm TL (Capapé et al. 2006). This species reaches a maximum size of ~180 cm TL (McEachran and de Carvalho 2002).
|Movement patterns:||Full Migrant|
|Use and Trade:||This species is not exploited or traded commercially.|
|Major Threat(s):||Historically, this electric ray was valued for its liver oil, which was used in lamps prior to the use of kerosene oil. Presently, it is occasionally caught incidentally by bottom trawls and line gear in commercial and recreational fisheries. It is usually discarded at sea, resulting in limited data on catches, and discard survival is unknown. The lack of catch data makes it difficult to determine population trends. As a large-bodied species, the Great Torpedo Ray may be biologically susceptible to depletion. The effect of bycatch on the population needs to be assessed. The species’ sensitivity to indirect effects of habitat degradation from destructive bottom trawling practices should also be assessed given that reef environments are suspected to be the preferred spawning habitat.|
There are no species-specific measures in place in the Mediterranean Sea. Accurate monitoring of catches and research on historical abundance are needed to determine the status of the population. Further research on life history characteristics is also required.
|Citation:||Bradai, M.N. & Ellis, J.R. 2016. Tetronarce nobiliana. The IUCN Red List of Threatened Species 2016: e.T161580A16527965.Downloaded on 22 June 2018.|
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