|Scientific Name:||Raja radula|
|Species Authority:||Delaroche, 1809|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Morey, G., Serena, F. & Mancusi, C.|
|Reviewer/s:||Valenti, S.V. & Musick, J.A. (Shark Red List Authority)|
This relatively small skate (to 70 cm TL) may be endemic to the Mediterranean Sea. Records from off Portugal and the northern coasts of Morocco require verification and may be misidentifications of other Raja species. The Rough Ray (Raja radula) occurs from coastal waters to 300 m depth, but appears to be more common at less than 40 m depth in some areas, such as the Balearic Islands. Where recorded in scientific trawl surveys in the northern Mediterranean, this species appears rare. In northern Mediterranean wide MEDITS scientific trawl surveys from 1994–1999 (at 50–800 m depth) the Rough Ray was captured in only 21 of 6,336 tows. It is the most abundant skate in shallow waters off the Balearic Islands (<40m depth), comprising about 25% in abundance and 12% in biomass of total elasmobranch catch in the trammel net fishery there. The Rough Ray is taken as bycatch of demersal trawl, gillnet, trammel net and bottom longline fisheries, although no specific data are available on catches. Given that this species appears to be restricted to the Mediterranean Sea and fishing pressure is relatively intensive in areas of its range, this species’ status may be of concern. At present insufficient information is available from across its range to assess it beyond Data Deficient. Further investigation is required to determine this species’ full range, abundance, interaction with fisheries and population trends.
|Range Description:||Occurs throughout the Mediterranean Sea, mainly in the western part and absent from the Black Sea (Serena 2005). The distribution may extend into the Atlantic Ocean, where it is reported from off Portugal and the northern coasts of Morocco, but these records require verification and may be misidentifications of other Raja species.|
Native:Albania; Algeria; Croatia; Egypt; France; Greece; Israel; Italy; Libya; Montenegro; Spain; Syrian Arab Republic; Tunisia; Turkey
|FAO Marine Fishing Areas:||
Atlantic – northeast; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
Recorded in low numbers where data are available from trawl surveys in the Mediterranean Sea, however it may be more common in shallow waters (<40 m depth) which were not sampled by some of the surveys mentioned below.
In comparable trawl surveys of the Gulf of Lions (France) from 1957–1960, 1980–1984, 1992–1995, (from the coast to 800 m depth) this species was only captured during the period 1980–1984, on the shelf and slope (Aldebert 1997). In northern Mediterranean wide MEDITS scientific trawl surveys from 1994–1999 (at 50–800 m depth) R. radula was captured in only 21 of 6,336 tows (Baino et al. 2001). In surveys conducted in Italian waters, it occurred in only 3.31% of 9281 hauls performed between 1985 and 1998 (at 0–800 m depth). It was only present in two areas (Sardinian and Sicilian waters) and was absent elsewhere in these surveys (Relini et al. 2000). It was not recorded during trawl surveys in the Adriatic Sea in 1948 or 1998 (Jukic-Peladic et al. 2001).
At least in the Balearic Islands, Spain, western Mediterranean, the species appears to be common in shallow waters. It was not recorded in 131 hauls during trawl surveys there from 1996–2001, at depths of 40–1,800 m (Massuti and Moranta 2003). However, it is the most abundant skate in shallow waters off the Balearic Islands (<40 m depth), comprising about 25% in abundance and 12% in biomass of total elasmobranch catch in the trammel net fishery there (Morey et al. 2006). Therefore the absence of this species from trawl surveys deeper than 40 m, at least off the Balearic Islands, is considered a result of its preference for shallow waters and perhaps the sampling gear.
|Habitat and Ecology:||
Raja radula is found from coastal waters to about depths of about 300 m (Stehmann and Bürkel 1984). In the Balearic Islands, this species is relatively common at less than 40 m depth.
Like all skates, reproduction is oviparous. About 80–154 paired eggs are laid per skate, per year (Walker 1998). Egg-cases measure 5.1–5.7 cm and are laid throughout the year, mainly in spring and summer and embryos develop in about four months (Serena 2005, Stehman and Bürkel 1984). Females mature at 34 cm DW and males at 30 cm DW (Serena 2005, Fischer et al. 1987). Maximum size to about 70 cm TL (Serena 2005, Fischer et al. 1987). Most captured specimens in the Balearic Islands measure about 30–50 cm TL (G. Morey unpub. data).
|Major Threat(s):||This species is taken as bycatch of demersal trawl, gillnet, trammel net and bottom longline fisheries. There is a high level of exploitation over the continental shelf and upper slope in the Mediterranean Sea (Massuti and Moranta 2003, Aldebert 1997). In some areas, such as the Balearic Islands, this species is more common in shallow waters, where it is taken in trammel net (targeting cuttlefish Sepia officinalis and teleost fishes), gillnet (targeting Lobster (Palinurus elephas) and Red Mullet (Mullus surmuletus)) and bottom longline fisheries (targeting groupers Epinephelus spp. and Sparidae) (Morey et al. 2006). Trawl fisheries operating on the upper shelf, targeting red mullet Mullus surmuletus, caramel Spicara smaris and small hake Merluccius merluccius in this area also partially overlap with its range. Species specific data are not available because landings of skates are grouped as ‘rays’.|
|Conservation Actions:||None in place. Research is required to determine this species’ full range, abundance, interaction with fisheries and population trends.|
|Citation:||Morey, G., Serena, F. & Mancusi, C. 2009. Raja radula. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 08 March 2014.|
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