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Raja polystigma

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RAJIDAE

Scientific Name: Raja polystigma
Species Authority: Regan, 1923
Common Name(s):
English Speckled Skate, Speckled Ray
French Raie Tachetée, Raie Douce
Spanish Raya Manchada, Raya Pintada
Taxonomic Notes: In some areas of the Mediterranean Sea (particularly along the Italian coasts) this species is probably misidentified with Raja montagui. Further investigation is required into this and morphometric and genetic studies are still in progress (Mancusi et al. 2005).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2014-12-17
Assessor(s): Ungaro, N., Dulvy, N.K., Tinti, F., Bertozzi, M., Notarbartolo di Sciara, G., Serena, F., Abella, A. & Walls, R.H.L.
Reviewer(s): Mancusi, C.
Facilitator/Compiler(s): Walls, R.H.L., Pardo, S.A. & Dulvy, N.K.
Justification:

Speckled Skate (Raja polystigma) is endemic to the Mediterranean Sea. This relatively small skate (up to 60 cm total length) mainly inhabits soft bottoms on the continental shelf at depths of 100-400 m. It shows a wide geographic range in the Mediterranean Sea (mostly western and western central areas) where it is moderately common. It is part of the bycatch in fisheries using bottom trawl nets, but is also fished with gillnets, longlines and handlines in artisanal fisheries. Although little is known of the effect of fisheries on population size, its entire range overlaps intensively trawled regions. Given its small-body size, it is likely to be able to withstand moderate levels of fishing pressure. Speckled Skate is therefore assessed as Least Concern, although the status of this endemic species should be monitored.

History:
2009 Near Threatened

Geographic Range [top]

Range Description:

Speckled Skate (Raja polystigma) is moderately common, endemic species throughout the Mediterranean Sea (Serena 2005), particularly in the western (Morocco, Spain and France) and western central areas (Tyrrhenia, Corsica, Sardinia and Sicily) (Baino et al. 2001, Ragonese et al. 2003, Florio et al. 2003, Follesa et al. 2003, Spedicato et al. 2003, Serena 2005, Mancusi et al. 2005), along northern African coasts (Stehmann and Bürkel 1984), and eastern Algerian coasts (Bertozzi et al. 2003). The species also exists in the southern Ligurian Sea (Vannucci et al. 2006) and around Asinara Island, northwest Sardinia (Catalano et al. 2007). It is rare in the Ionian Seas (Notarbartolo di Sciara and Bianchi 1998, Mytilineou et al. 2005). In the Adriatic Sea, it is rarely captured.

Countries:
Native:
Albania; Algeria; France (Corsica, France (mainland)); Greece (Greece (mainland)); Italy (Italy (mainland), Sardegna, Sicilia); Libya; Morocco; Spain (Baleares, Spain (mainland)); Tunisia
FAO Marine Fishing Areas:
Native:
Mediterranean and Black Sea
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

The species is found predominantly on the shelf and has been caught in the MEDITS program at depths up to 500 m (Baino et al. 2001). It is the third most abundant skate species captured in trawl surveys performed in the south Ligurian and north Tyrrhenian Sea from 1985-2004 after Thornback Skate (R. clavata) and Brown Skate (R. miraletus). In this area it occupies a very wide depth range (20-633 m) but is more concentrated between 300 and 400 m. Important catches of juveniles were recorded occasionally. Most of the collected specimens measured between 12 and 49 cm in length (Serena et al. 2005).

A study of commercial bottom trawl catch from 1995 to 2006 in the Aegean Sea caught a total of 203 specimens, with a mean catch per unit effort (CPUE) of 2.07 kilograms per hour, or 6.33 individuals per hour (Damalas and Vassilopoulou 2011). Of this catch, the majority was discarded (77.72% in weight; 93.60% in number) and the remaining fraction marketed (22.28% in weight; 6.40% in number). The same authors reported that fishery-dependent mean nominal CPUE of Speckled Skate in the central Aegean Sea has increased by 98.69% from a mean value of 0.01 individuals per hour (< 0.01 kg/h) between 1995 and 2000 to 0.71 individuals per hour (0.23 kg/h) between 2003 and 2006.

Due to the high degree of morphological similarity with Spotted Skate (Raja montagui), in the past many Speckled Skate captured in the scientific surveys have been incorrectly identified as Spotted Skate (Cannas et al. 2008).

Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The species is benthic, and it inhabits mainly soft bottoms from 100-400 m (Serena 2005), but with a wide depth range from 20-633 m. Both males and females are estimated to mature at 40-53 cm total length (TL) with a maximum recorded size of 60 cm TL (Tortonese 1956, Bini 1967, Bauchot 1987, Stehmann and Burkel 1984, Notarbartolo di Sciara and Bianchi 1998, Serena 2005). It is common at sizes of 30-40 cm TL (Bauchot 1987). Like other skates, this species is egg laying. Reproduction takes place in winter and 20-62 egg cases (depending on size) are laid per year (Bauchot 1987, Stehmann and Burkel 1984, Serena 2005). The egg-cases measure 46 by 35 mm excluding horns (Stehmann and Burkel 1984, Serena 2005).
Systems: Marine

Use and Trade [top]

Use and Trade: The species is known to be marketed along African coasts of the Mediterranean Sea (Bauchot 1987).

Threats [top]

Major Threat(s):

The species is caught as bycatch in demersal trawl fisheries but is also fished with gillnets, longlines and handlines in artisanal fisheries (Bauchot 1987). There is a high level of exploitation over the continental shelf and upper slope, up to a depth of 800 m in the Mediterranean Sea (Massuti and Moranta 2003). Benthic trawl effort has increased both numerically and in technological terms in the shelf and slope area of the Mediterranean Sea over the past 50 years, even though a small decline occurred in recent years. For example, the Gulf of Lions area resources were initially exploited by small-scale benthic trawl fisheries comprising 27 small low powered boats (total nominal horse power of 2,700 hp), more recently effort has increased to a total nominal horse power of 19,940 hp (1974-1987) (Aldebert 1997).

It is known to be retained and marketed along the African coasts of the Mediterranean Sea, where both trawl and artisanal fisheries operate (Bauchot 1987). This species is rarely landed separately from other rays in Italian Seas and it is not possible to monitor catches. An increase in CPUE and decrease in discards is reported in the central Aegean Sea (Damalas and Vassilopoulou 2011).

Conservation Actions [top]

Conservation Actions: There are no specific measures for the management or conservation of this species in the Mediterranean Sea. Landings are allowed without any minimum legal landing size nor catch limits. Fisheries regulations in the Mediterranean Sea are based on effort control (some measures of effort reduction have been implemented) and technical adjustments, such as minimum mesh size for bottom trawl, which are too small to enable escapement of even the smallest Speckled Skate individuals. Further research should be conducted on the population size and trend of the species.

Bibliography [top]

Aldebert, Y. 1997. Demersal resources of the Gulf of Lions (NW Mediterranean). Impact of exploitation on fish diversity. Vie et Millieu 47: 275–284.

Baino, R., Serena, F., Ragonese, S., Rey, J. and Rinelli, P. 2001. Catch composition and abundance of Elasmobranchs based on the MEDITS program. Rapp. Comm. int. Mer Mèdit 36: 234.

Bauchot, M.L. 1987. Raies at autres batoidés. In: M. Fisher, M. Schneider and M.-L. Bauchot (eds), Fiches FAO d'Identification des Espècs pour les Besoins de la Peche. Méditerranée et Mer Noire. Zone de Peche 37. Revision 1. II, pp. 847-885. FAO, Rome.

Bertozzi, M., Pasolini P., Hemida F., Capapé C. and Tinti, F. 2003. Species diversity in Algerian skates. Proceedings of the 7th European Elasmobranch Association Meeting: 38. San Marino.

Bini G. 1967. Atlante dei pesci delle coste italiane: Leptocardi, Ciclostomi, Selaci. Mondo Sommerso, Milan.

Cannas, R., Pasolini, P., Mancusi, C., Follesa, M.C., Cabiddu, S., Hemida, F., Serena, F. and Tinti, F. 2008. Distribution, molecular systematics and phylogeography of Raja polystigma and Raja montagui in the Mediterranean. Biologia Marina Mediterránea 15(1): 188-191.

Catalano, B., Dalù, M., Scacco, M. and Vacchi, M. 2007. New biological data of Raja brachyura (Chondrichthyes, Rajidae) from around Asinara Island (NW Sardinia, Western Mediterranean). Italian Journal of Zoology 74: 55-61.

Damalas, D. and Vassilopoulou, V. 2011 . Chondrichthyan by-catch and discards in the demersal trawl fishery of the central Aegean Sea (Eastern Mediterranean). Fisheries Research 108: 142-152.

Florio G., Consoli P., Prdichizzi F., Rinelli P. and Greco S. 2003. Annotated check list of the skates (Chondrichthyes, Rajidae) in the south-Tyrrhenian sea from Cape Suvero (Calabria) to Cape S. Vito (Sicily). Biologia Marina Mediterranea 10(2): 824-827.

Follesa, M.C., Addis, P., Murenu, M., Saba, R., and Sabatini, A. 2003. Annotated check list of the skates (Chondrichthyes, Rajidae) in the Sardinian seas. Biologia Marina Mediterranea 10(2): 828-833.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015.1. Available at: www.iucnredlist.org. (Accessed: 28 May 2015).

Mancusi C., Pasolini P., Serena F., Tinti F. 2005. Taxonomic discrimination of Raja polystigma and Raja montagui in the Mediterranean Sea based on the comparative analysis of morphometric and genetic markers. 9th Meeting of the European Elasmobranch Association E.E.A. Book of abstracts. Principality of Monaco.

Massuti, E. and Moranta, J. 2003. Demersal assemblages and depth distribution of elasmobranchs from the continental shelf and slope off the Balearic Islands (western Mediterranean). ICES Journal of Marine Science 60: 753-766.

Mytilineou, C., Politou, C.Y., Papaconstantinou, C., Kavadas, S., D'Onghia, G. and Sion, L. 2005. Deep-water fish fauna in the Eastern Ionian Sea. Belgium Journal of Zoology 135(2): 229-233.

Notarbartolo di Sciara, G. and Bianchi, I. 1998. Guida degli squali e delle razze del Mediterraneo. Muzzio, Padova.

Ragonese, C.S., Cigala Fulgosi, F., Bianchini, M.L., Norrito, G. and Sinacori, G. 2003. Annotated check list of the skates (Chondrichthyes, Rajidae) in the Strait of Sicily (Central Mediterranean). Biologia Marina Mediterranea 10(2): 874-881.

Serena F. 2005. Field identification guide to the sharks and rays of the Mediterranean and Black Sea. FAO, Rome.

Serena, F., Mancusi, C., Barone, M. and Abella, A.J. 2005. Abundance and distribution of rays in the south Ligurian and north Thyrrenian Sea. 2005 ICES Annual Science Conference CM2005/N:20. Aberdeen, Scotland, UK.

Spedicato M.T., lembo G. and Carbonara P. 2003. Annotated check list of the skates (Chondrichthyes, Rajidae) in the central-southern Tyrrhenian sea. Biologia Marina Mediterranea 10(2): 941-945.

Stehmann, M. and Bürkel, D.L. 1984. Rajidae. In: P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (eds), Fishes of the North-eastern Atlantic and Mediterranean, pp. 163-196. UNESCO, Paris.

Tortonese, E. 1956. Fauna d'Italia: Leptocardia, Ciclostomata, Selachii. Calderini, Bologna.

Vannucci, S., Mancusi, C., Serena, F., Cuoco, C. and Volani, A. 2006. Feeding ecology of rays in the southern Ligurian Sea. Biologia Marina Mediterranea 16: 296-97.


Citation: Ungaro, N., Dulvy, N.K., Tinti, F., Bertozzi, M., Notarbartolo di Sciara, G., Serena, F., Abella, A. & Walls, R.H.L. 2015. Raja polystigma. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 04 July 2015.
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