|Scientific Name:||Scyliorhinus stellaris (Linnaeus, 1758)|
Squalus stellaris Linnaeus, 1758
|Taxonomic Notes:||Possibly sometimes confused with the smaller Scyliorhinus canicula.|
|Red List Category & Criteria:||Near Threatened (Regional assessment) ver 3.1|
|Assessor(s):||Ellis, J.R., Serena, F., Mancusi, C., Haka, F., Morey, G, Guallart, J. & Schembri, T.|
|Reviewer(s):||Walls, R.H.L. & Allen, D.J.|
Mediterranean regional assessment: Near Threatened (NT)
The Nursehound is a medium-large catshark (up to 150 cm total length) that occurs in coastal and inshore waters of the Mediterranean Sea. It is found at depths of less than five metres to ~400 m in this region, but is most common between 20 and 63 m. It is taken as bycatch in bottom trawl, gill net, and longline gears, and targeted by artisanal fisheries for local consumption. Trawl surveys do not sample the main habitats for this species and cannot therefore be relied upon for accurate population estimates. In the Mediterranean Sea, the limited data available on exploitation and abundance indicate that the population is declining, particularly around the Balearic Islands and in the heavily fished northwest Mediterranean Sea. The capacity for recovery is affected by potentially low levels of connectivity between discrete subpopulations around islands far from the continental coast. The larger size of this species may deem it more sensitive to exploitation than its congener, the Small Spotted Catshark (S. canicula), which also occurs in the region but appears to be increasing in abundance. Given its larger size, patchy range, and evidence for declines in areas of the Mediterranean Sea such as the Gulf of Lions, the Nursehound is inferred to have undergone a decline of nearly 30% over the past three generation period (45–60 years). It is therefore assessed as Near Threatened in the Mediterranean Sea, close to qualifying for Vulnerable under Criterion A2bd.
|Range Description:||The Nursehound appears to be more abundant in the Adriatic and Ionian Seas and along the Albanian coast, compared to the western Mediterranean Sea (Baino et al. 2001). It was absent from trawl surveys conducted off the coasts of Morocco, Spain, and France (Compagno et al. 2005). It has been found from the surface to 409 m depth.|
Native:Albania; Algeria; Bosnia and Herzegovina; Croatia; Cyprus; Egypt (Egypt (African part), Sinai); Greece (East Aegean Is., Greece (mainland), Kriti); Israel; Italy (Italy (mainland), Sardegna, Sicilia); Lebanon; Libya; Montenegro; Palestinian Territory, Occupied; Slovenia; Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
|FAO Marine Fishing Areas:|
Mediterranean and Black Sea
An increase in fishing effort in the Gulf of Lions (see Threats section) corresponded to a decline in abundance of the Nursehound in a long-term groundfish diversity study, where abundance declined steadily from 1970 to the 1980s, and it became entirely absent from Gulf of Lions catches after 1988 (Aldebert 1997). In the Balearic Islands, 131 survey hauls were made between 40 and 1,800 m depth from 1996–2001, and whereas two other catshark species had the highest reported abundances of all elasmobranch species, this catshark was entirely absent (Massutí and Moranta 2003). More recently, 12 trammel net surveys carried out in the Balearic Islands between 2000 and 2003 also captured no specimens around the Balearic Islands (Morey et al. 2006). In the western half of the Adriatic Sea this species was considered rare as far back as 1987 (Jardas 1984), although it was recorded in trawl surveys carried out in 1948 and 1998, suggesting that it may still have been present in low numbers (Jukic-Peladic et al. 2001). Given the absence of this catshark in numerous trawl surveys, and reported declines in abundance corresponding with increased fishing effort, it is estimated to be decreasing in the Mediterranean Sea.
Considering the abundance trends from Aldebert (1997), a decline of 94–98% of baseline levels is estimated for the three generation period (1957–2001, 1957–2016, 45–60 years) for the Gulf of Lions. However, according to Baino et al.(2001), this species is more rare in the western Mediterranean and more abundant in other regions in the Mediterranean Sea, and therefore the Gulf of Lions may not be representative of the Mediterranean-wide population. It is thus inferred that the Nursehound has declined by almost 30% in the Mediterranean Sea over the past three generations (45–60 years).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
The Nursehound is found from the shallow subtidal to the continental platform, most commonly at depths of 20–63 m (Compagno et al. 2005), but with a maximum depth down to ~400 m (Bauchot 1987, Serena 2005). Within the northern Tyrrhenian and southern Ligurian Seas, this species is distributed from 55–409 m depth (Baino and Serena 2000). It often occurs over rough or rocky inshore substrates, or surfaces with algal cover. In the Mediterranean Sea it has been found over coralline algal substrates (Compagno et al. 2005), and reportedly has active breeding areas in the Ligurian Sea and in the waters surrounding the Tuscan archipelago (De Sabata and Clò 2013).
This egg laying species deposits large, 10–13 cm long thick-walled egg cases on algae in the subtidal or lower intertidal zone during spring and summer (Ellis et al. 2005). Egg case deposits have been found on rocky reefs in the Mediterranean Sea, mostly between 30 and 50 m depth (De Sabata and Clò 2013). Once the eggs are deposited they take up to nine months to hatch with size at birth reportedly 10–16 cm total length (TL; Tortonese 1956, Bauchot 1987). Males mature at 77 cm TL and females at 79 cm TL (Bauchot 1987). The maximum reported length for this catshark in the Mediterranean Sea is 150 cm TL, with a common average size of 40–55 cm TL (Bauchot 1987). The generation length is estimated as 15–20 years, based on estimates of three scyliorhinid species (the Blacktip Sawtail Catshark, Galeus sauteri; the Dark Shyshark, Haploblepharus pictus; and the Leopard Catshark, Poroderma pantherinum).
|Generation Length (years):||15-20|
|Movement patterns:||Not a Migrant|
|Use and Trade:||This is a moderately important commercial species in Mediterranean waters.|
|Major Threat(s):||Overfishing appears to be the major cause driving the decline of this catshark in the Mediterranean region, and low connectivity may be limiting population recovery. It is taken as bycatch in several semi-industrial fisheries in Spain, the Adriatic Sea, Sicily, and Cyprus. Artisanal fisheries catch this species elsewhere, as it is regularly present in fish markets in Malta, Tunisia, Greece, Cyprus, and Turkey. Demersal trawl effort has increased both numerically and technologically in the shelf and slope areas. For example, from 1974–87, effort in trawl fisheries in the Gulf of Lions increased from a small, low powered fleet with a total of 2,700 hp (horse power) to a total of 19,940 hp (Aldebert 1997). Little information on landings and catches exists for this species, partly due to the lack of species-specific data. In many areas, for example the Balearic Islands and Italian waters, reported landings and catch data group this species with the more common Small Spotted Catshark (S. canicula) or even more generally with all other demersal elasmobranch species.|
|Conservation Actions:||The Nursehound species is protected in six marine reserves around the Balearic Islands, but enforcement is unclear. No other species-specific conservation measures are in place throughout its Mediterranean range. Monitoring of the population and further protection measures are therefore encouraged.|
|Citation:||Ellis, J.R., Serena, F., Mancusi, C., Haka, F., Morey, G, Guallart, J. & Schembri, T. 2016. Scyliorhinus stellaris. The IUCN Red List of Threatened Species 2016: e.T161484A16527873.Downloaded on 18 February 2018.|
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