|Scientific Name:||Leucoraja fullonica|
|Species Authority:||(Linnaeus, 1758)|
Raja fullonica Linnaeus, 1758
|Red List Category & Criteria:||Vulnerable A2bd ver 3.1|
|Assessor(s):||McCully, S. & Walls, R.|
|Reviewer(s):||Ellis, J. & Mancusi, C.|
|Contributor(s):||Serena, F., Dulvy, N., Ungaro, N., Tinti, F., Bertozzi, M., Pasolini, P., Notarbartolo di Sciara, G. & Fordham, S.|
|Facilitator/Compiler(s):||Walls, R., Lawson, J. & Dulvy, N.|
Shagreen Skate (Leucoraja fullonica) is an offshore species, usually occurring on the outer parts of the continental shelf, at depths of 30–550 m, and it has occasionally been recorded beyond 550 m in the Mediterranean Sea. In the Northeast Atlantic this skate is taken as bycatch in demersal trawl and longline fisheries throughout much of its range. Reported French landings were more than 370 tonnes in 1983, but since 1984 annual landings have been more stable and averaged about 75–150 tonnes. Recent captures of this species in Scottish surveys have been made in waters > 200 m deep, suggesting that its range has been constricted to deeper waters. However, accurate trends in abundance are hard to determine due to changes in survey techniques, as well as some uncertainty in the taxonomic identification in earlier surveys. It is suspected that there have been continuing population declines of 30-50% over three generations for the Northeast Atlantic subpopulation.
Few data are available on this skate in the Mediterranean Sea, where it was recorded in only seven of 6,336 tows between 1994 and 1999 at depths ranging from 10–800 m during the International Trawl Survey in the Mediterranean. More recent records from 2008–2009 identified ten specimens in the southern Adriatic Sea, an area that this species was previously suspected to be absent from, although these records could be misidentifications. This species is rare in Mediterranean trawl surveys. However, this skate likely has a low intrinsic rate of increase suggested by its large body size and large size at maturity. Therefore, further analyses of survey data and close monitoring are needed to elucidate the long-term distribution and relative abundance of this species.
It is assumed that the rate of decline in the Mediterranean Sea is at least the same or worse than the NEA due to near absence of effective fisheries management there. Therefore it is inferred that this species meets the threshold for Vulnerable, given an estimated 30-50% overall decline in a three generation span from the NEA (from ICES 2012) and suspected 30-50% decline throughout European waters overall in a three generation span. This species potentially meets the threshold for Endangered and thus should be monitored, particularly in the Mediterranean.
In the Northeast Atlantic this skate occurs in the offshore waters of the continental shelf from Madeira and northern Morocco. Northwards it is present but sparse in the Norwegian Sea including the Skagerrak, Icelandic waters, the Faroe Islands and east of Greenland (Stehmann and Bürkel 1984, ICES 2012). It occurs in low numbers west of Scotland at Rockall Bank, in the Bay of Biscay region, in Iberian waters and around the Azores and mid-Atlantic ridge (ICES 2012). In the Mediterranean Sea it is known from the western and eastern central areas to Tunisia and western coasts of Greece, including the southern Adriatic Sea (Stehmann and Bürkel 1984, Bauchot 1987, Bertrand et al. 2000, Relini et al. 2000, Marano et al. 2003, Tinti et al. 2003, Serena et al. 2011).
Native:Albania; Algeria; Denmark; Faroe Islands; France (France (mainland)); Greece (Greece (mainland)); Iceland; Ireland; Israel; Italy (Italy (mainland), Sicilia); Montenegro; Morocco; Norway; Portugal (Azores, Madeira, Portugal (mainland)); Spain (Spain (mainland)); Tunisia; United Kingdom (Great Britain, Northern Ireland)
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northeast; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
It is likely that there is poor connection between the two deepwater subpopulations of the Northeast Atlantic and Mediterranean Sea. The overall population trend of this species is of a decrease.
Accurate determination of abundance trends in the Northeast Atlantic is not possible, in the absence of long-term, standardised surveys sampling off the edge of the continental shelf. Historically, this species may have been more widely distributed in shelf areas in the Northeast Atlantic. Reported French landings for this species were more than 370 tonnes (t) in 1983, but since 1984 annual landings have been more stable and averaged about 75–150 t. English surveys in the North Sea have not recorded this species since 1998, though occasional specimens are taken in the Celtic Sea. It is now encountered only infrequently in surveys on the inner continental shelf, though is still present in deeper waters along the edge of the continental shelf, suggesting that the main part of the range has contracted to deeper water. Indeed, most recent catches in Scottish surveys have been made in waters deeper than 200 m.
Catches of this skate around Iceland and eastern Greenland has been relatively stable overall, ranging from two tonnes in 1993 to 17 t in 2011, with the highest catch of 37 t recorded in 2001 (ICES 2012). While these catch volumes are low, confusion with Sailray (Rajella lintea) is believed to still occur, suggesting that true catch volumes may be even lower. The French Evaluation Halieutique Ouest Européen (EVHOE) Groundfish survey suggested an overall declining trend in abundance and biomass in waters west of Scotland and Ireland between 1997 and 2011, although this decline appeared to be stabilizing in 2010–2011 (ICES 2012). French landings from the Bay of Biscay and Iberian waters have increased from three tonnes in 2000 to 32 t in 2011 (ICES 2012). Spanish landings from this region have been consistently low and stable, ranging from four tonnes in 2000 to eight tonnes in 2008. Purported Scottish landings of White Skate (Rostroraja alba) from these waters may also refer to Shagreen Skate (Leucoraja fullonica) because White Skate is considered depleted in this area (ICES 2013). Although levels of exploitation are unknown for this subpopulation, it is inferred to be declining due to a decrease in survey catch rates and landings.
This species was captured at depths ranging from 200–800 m in only seven of 6,336 tows during the International Trawl Survey in the Mediterranean (MEDITS) performed throughout the northern Mediterranean Sea from 1994–1999 in depths ranging from 10–800 m (Baino et al. 2001). It was absent from multiple trawl survey time series data that ran from 1957–1995 and consisted of eight separate surveys conducted by four different survey vessels in the Gulf of Lions in the eastern Mediterranean Sea (Aldebert 1997). Additionally, it was was absent from both recent and historical surveys in the Adriatic Sea (Jukic-Peladic et al. 2001). While further MEDITS surveys from 2008–2009 found ten specimens of the species in the southern Adriatic Sea (Zupa et al. 2010), an area it was previously thought to be absent from, it is possible that these specimens may have been incorrectly identified Sandy Skate (Leucoraja circularis). Trawl surveys in the south Ligurian Sea and north Tyrrhenian Sea suggest that the species is rare there, with few specimens captured between 1985 and 2004 at depths of 366–549 m (Serena et al. 2005). The trajectory of the Mediterranean Sea subpopulation is currently unknown.
|Habitat and Ecology:||
This benthic skate is found in offshore shelf and upper slope waters on sandy and coarse bottoms, predominantly found around 200 m depth but ranging from 30–800 m (Stehmann and Bürkel 1984, Ellis et al. 2005). In the Mediterranean Sea, it occurs in relatively cold coastal waters and on upper parts of continental slopes in about 30–550 m, but has also been captured in deeper water down to 800 m (Stehmann and Bürkel 1987, Bertrand et al. 2000, Baino et al. 2001).
Little is known about the biology and reproductive cycle of this relatively large-bodied skate. It is an egg laying species, producing egg cases that measure about 8 by 5 cm (Stehmann and Bürkel 1984). Specimens caught in the Celtic Seas and North Sea between 1992 and 2011 ranged from 21 to 96 cm and 24 to 70 cm total length (TL) in males and females, respectively (McCully et al. 2012). All female specimens were immature, while only two males at 75 and 96 cm TL were mature. The largest immature male caught was 82 cm TL. This species reaches a maximum size of 100–110 cm (Bauchot 1987). Based on the information available for its congener, L. naevus, the species has an estimated generation length of 9.7 years.
|Use and Trade:||There is no information on the use and trade of this species.|
The relatively large body size of this skate suggests that it is sensitive to exploitation. It is taken as bycatch in mixed demersal fisheries through much of its range, including mixed trawl fisheries operating in the outer parts and edge of the continental shelf in both the Northeast Atlantic and the Mediterranean Sea. In the Mediterranean Sea it is also caught as bycatch by both bottom trawl and longline fisheries (Stehmann and Bürkel 1984, Serena 2005). In the Northeast Atlantic it may also be taken as a bycatch in gillnet fisheries targeting anglerfish and longline fisheries targeting hake, though information on the catches in these fisheries are poor.
In 1999, the European Union (EU) introduced a Total Allowable Catch (TAC) for skates and rays of 6,060 t for fisheries operating in the Norwegian Sea (International Council for the Exploration of the Sea [ICES] Division IIa) and North Sea (ICES sub-area IV) based on landing statistics from the previous five years. This TAC has been progressively reduced by 8−25% annually to the current level of 1,256 t. As part of the TAC, the bycatch quota for vessels over 15 metres was set at 25% of live weight of catch retained on board per trip. For much of this period (1999−2014), the TAC was higher than reported landings and therefore not effectively constraining catches. Additional management measures, including a 2006 permanent ban on all deepwater gillnet fisheries at depths of > 600 m imposed by the European Commission (EC), may help to protect the deeper range of this species. The EC also imposed maximum limits on the length of nets deployed and the soak time in the remaining fisheries at depths of < 600 m (EC Regulation No. 41/2006).
Skate and ray TACs were established for other EU waters in 2009, including the Skagerrak and Kattegat (ICES Division IIIa) and from the northwest coast of Scotland and Northern Ireland to Portuguese waters (ICES sub-areas VI−IX). These TACs have also been gradually reduced since then. In 2013, the TAC for all skate and ray species grouped was 21,800 t (regulations are available online at http://faolex.fao.org). Since 2008, the European Commission has obliged member states to provide species-specific landings data for the major North Sea species, including this species, in order to improve understanding of skate stocks in the area (CEC 2008). In 2009, this obligation was extended to other ICES divisions, including the Celtic Seas (CEC 2009), and has been ongoing since 2008 (CEC 2013). Additional management measures, including non-trawling areas in the Mediterranean Sea, could benefit this species as a fraction of the adult population and eggs are often found in trawl cod-ends (Ragonese et al. 2003).
|Citation:||McCully, S. & Walls, R. 2015. Leucoraja fullonica. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 31 August 2015.|
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