|Scientific Name:||Gymnura altavela (Linnaeus, 1758)|
|Red List Category & Criteria:||Critically Endangered A2bd (Regional assessment) ver 3.1|
|Assessor(s):||Walls, R.H.L., Vacchi, M., Notarbartolo di Sciara, G., Serena, F. & Dulvy, N.K.|
|Reviewer(s):||Bariche, M., Walls, R.H.L. & Allen, D.J.|
|Contributor(s):||Vooren, C.M., Piercy, A., Snelson, F.F. & Grubbs, D.|
|Facilitator/Compiler(s):||Walls, R.H.L. & Dulvy, N.K.|
Mediterranean regional assessment: Critically Endangered (CR)
The Spiny Butterfly Ray (Gymnura altavela) is wide-ranging but patchily distributed in tropical and warm temperate continental shelf waters, found throughout the coastal waters of the Mediterranean Sea. This ray is large (up to 220 cm disc width; DW) with a small litter size (one to three pups in the Mediterranean region), which suggests it is intrinsically susceptible to population depletion. The species was moderately abundant and catchable in the Mediterranean region historically. During the last century it was not uncommon in the catch of demersal trawl and set net fisheries throughout the Mediterranean Sea, the southern shores in particular, until the 1980s. In the Sicilian Channel it was previously quite frequently captured but is now very rare or absent from local catch records. It has also been absent from the International Trawl Survey in the Mediterranean (MEDITS) records since 1994. Reports of its presence are based on the capture of occasional specimens in demersal fisheries. It is relatively abundant along the Levant coasts where it is regularly caught with bottom trawls, fixed nets, and longlines. Given its current rarity throughout much of the Mediterranean Sea (despite comprehensive survey work carried out throughout its historical range), it is suspected that this species has declined significantly in the past 30 years and disappeared from much of its historical range. Its previously known range continues to face high levels of fishing pressure and habitat degradation from coastal development. The Spiny Butterfly Ray is therefore assessed as Critically Endangered in the Mediterranean Sea on the basis of a suspected decline exceeding 80% over the past three-generation period (~20 years).
|Range Description:||The Spiny Butterfly Ray is patchily distributed across continental shelf waters of the Mediterranean Sea (McEachran and Fechhelm 1998, Serena 2005).|
Native:Albania; Algeria; Cyprus; Egypt (Egypt (African part), Sinai); Greece (East Aegean Is., Greece (mainland)); Israel; Italy; Lebanon; Libya; Malta; Montenegro; Morocco; Spain (Baleares, Spain (mainland) - Possibly Extinct, Spanish North African Territories); Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
Possibly extinct:Bosnia and Herzegovina; Croatia; France (Corsica, France (mainland)); Monaco; Slovenia
|FAO Marine Fishing Areas:|
Mediterranean and Black Sea
Historically, the Spiny Butterfly Ray was not uncommon in the catch of demersal trawl and set net fisheries throughout the Mediterranean Sea, the southern part in particular. It is still regularly present in some parts of the southern and eastern Mediterranean Sea (Bariche 2012). There have been no records of the species from the MEDITS surveys since 1994 (Baino et al. 2001), indicating that it is perhaps absent from most of the northern Mediterranean Sea. The cod-end mesh size of the MEDITS gear of 20 mm is sufficient to catch this species, and the surveys occur throughout its depth range and habitat-type, ruling out the possibility that it may not be susceptible to this survey equipment. Occasional specimens turn up in the catch of demersal fisheries; for example, one adult male was captured recently near Anzio, Italy (Psomadakis et al. 2005) and another specimen in the southern Adriatic Sea in 2000 (Dulcic et al. 2003), confirming that it is not yet locally extinct in the central Mediterranean Sea.
Species abundance is suspected to have continuously decreased in recent decades because fisheries in the Mediterranean Sea have not contracted or reduced effort. The lack of data available on this species from both surveys and fisheries is an indication of its scarcity in the region. Perhaps in western and northern areas where fishing is most intensive, this could be an indication of disappearance from the region.
It is suspected that a population decline of more than 80% has occurred for this species in the Mediterranean Sea over the past three-generation period (~20 years), based on its disappearance from catch records in several locations and recent rarity in others.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
This is a large batoid that was once locally abundant with a patchy range. It is found in shallow coastal waters over sandy, muddy, and shelly detrital substrates and sometimes on Posidonia beds (seagrass) from 10–100 m depth (Capapé et al. 1992, McEachran and Fechhelm 1998, Serena 2005).
Little is known of the Spiny Butterfly Ray's biology. Maximum size may reach 400 cm DW, but usually up to 200 cm DW (Stehmann 1981). Size at maturity is reported as 155 cm DW in males and 102 cm DW in females (Daiber and Booth 1960). Reproduction is aplacental yolk-sac viviparous, with one to three pups per litter in the Mediterranean Sea (Tortonese 1956). It reproduces annually and reported gestation time is four to nine months (Capapé et al. 1992). Size at birth ranges from 38–44 cm DW (Bigelow and Schroeder 1953, McEachran and Carvalho 2002). Generation length is inferred from similar species as approximately six to seven years.
|Generation Length (years):||6-7|
|Movement patterns:||Not a Migrant|
|Use and Trade:||The Spiny Butterfly Ray is not used or traded commercially.|
|Major Threat(s):||This ray is a bycatch of coastal demersal fisheries but not targeted. Towards the end of the 20th century, benthic trawl effort in the Mediterranean Sea increased both numerically and technologically. For example, the Gulf of Lions area was initially exploited by small-scale benthic trawl fisheries comprising 27 small low-powered boats (total nominal horse power of 2,700 hp), but effort increased seven-fold to a total of 19,940 hp between 1974 and 1987. Following this, half of the benthic trawl fishing effort was displaced to target small pelagic fishes (Aldebert 1997). The Adriatic Sea is subject to trawling mainly by Italian, Croatian, Slovenian, and Albanian fleets but landings data are not available (Jukic-Peladic et al. 2001). Coastal development, pollution, and anthropogenic disturbance through tourism activities are also a threat to the shallow coastal habitat of this species.|
The Spiny Butterfly Ray was listed in Appendix II of the Barcelona Convention. Parties to the Barcelona Convention agreed in 2012 that all elasmobranch species listed in Annex II of the Protocol concerning Specially Protected Areas and Biological Diversity in the Mediterranean Sea (which includes Recommendation GFCM/36/2012/1) cannot be retained on board, transshipped, landed, transferred, stored, sold or displayed or offered for sale, and must be released unharmed and alive, to the extent possible.
Research should be conducted on the population size and trend of this species to confirm potential local extinctions throughout the Mediterranean Sea.
|Citation:||Walls, R.H.L., Vacchi, M., Notarbartolo di Sciara, G., Serena, F. & Dulvy, N.K. 2016. Gymnura altavela. The IUCN Red List of Threatened Species 2016: e.T63153A16527909.Downloaded on 16 August 2018.|
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