|Scientific Name:||Scyliorhinus stellaris|
|Species Authority:||(Linnaeus, 1758)|
Squalus stellaris Linnaeus, 1758
|Taxonomic Notes:||Possibly sometimes confused with the smaller Scyliorhinus canicula.|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor/s:||Ellis, J., Serena, F., Mancusi, C., Haka, F., Morey, G., Guallart, J. & Schembri, T.|
|Reviewer/s:||Dudley, S., Soldo, A., Francis, M. & Valenti, S.V. (Shark Red List Authority)|
The Nursehound (Scyliorhinus stellaris) is a large-bodied catshark that occurs inshore and offshore in the northeast and eastern central Atlantic, over the continental shelf between southern Scandinavia and Senegal, and is also present throughout the Mediterranean. It is found at depths of 1?2 m to at least 125 m, but is most common in depths of 20?63 m, and in relatively shallow waters in northern areas of the northeast Atlantic. Around the British Isles, it is locally abundant in certain areas (e.g., the coasts of Pembrokeshire, Anglesey, Lleyn Peninsula and Cardigan Bay), but may be at risk from localised depletion. This species is fished by bottom trawls, gill nets, bottom set long lines, handlines and fixed bottom nets, and occasionally pelagic trawls. Although limited data are available on the exploitation and trends in abundance, declines have been indicated in the Mediterranean Sea, particularly around the Balearic Islands and in the northwest Mediterranean. The capacity for recovery of this species is affected by a low level of interconnectivity between isolated populations around islands far from the continental coast. Little information is available on its biology, however, it is a large bodied species and is likely more vulnerable to population depletion than the Smallspotted Catshark (S. canicula), which also occurs in the region. Given its large size, patchy distribution and evidence for declines in areas of the Mediterranean Sea, an assessment of at least Near Threatened is warranted. There is concern that it may qualify for VU A4bd in the future.
|Range Description:||Northeast and eastern central Atlantic and Mediterranean Sea: distributed from the Shetland Isles and southern Norway in the north, to Senegal in the south. Records further south in the Atlantic, to Gulf of Guinea and Congo may be misidentifications of Scyliorhinus cervigoni. It is found throughout the Mediterranean Sea, but does not occur in the Black Sea. (Compagno et al. 2005, Notarbartolo and Bianchi 1998, Whitehead et al. 1984, Fischer et al. 1987, Bauchot 1987, Serena 2005).
In the Mediterranean, this species appears to be more abundant in the eastern central basin (the Adriatic and Ionian seas and Albanian coasts) compared to the western regions (Baino et al. 2001). This species was not caught in the trawl surveys conducted off the coasts of Morocco, Spain and France. However, it should be noted that the bottom trawl net is not the most appropriate gear for sampling this species. It is common on rocky bottoms or coralline grounds to 400 m of depth but more common between 20 and 150 m in the coastal areas of the continental platform (Bauchot 1987). The mating and nursery grounds as well as the extent of this species? movements throughout the Mediterranean are not known.
It also occurs in coastal and shallow shelf seas of the Northeast Atlantic, from the Shetland Isles and southern Norway in the north, to north-west Africa in the south. Around the British Isles, it is uncommon in the North Sea, and more common off southern and western coasts. Areas where it seems most abundant include parts of the English Channel and Bristol Channel, Cardigan Bay and around the Lleyn Peninsula and Anglesey (Ellis et al. 2005a). It tends to be most abundant on coarse and rocky inshore grounds, and such habitats tend to be under-represented in trawl surveys.
Native:Albania; Algeria; Belgium; Croatia; Denmark; Egypt; France; Germany; Greece; Ireland; Israel; Italy; Libya; Mauritania; Montenegro; Morocco; Netherlands; Norway; Portugal; Senegal; Spain; Syrian Arab Republic; Tunisia; Turkey; United Kingdom; Western Sahara
|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.|
Scyliorhinus stellaris is less abundant than S. canicula (Compagno in prep).
This species was reported in only 34 of 6336 (1%) tows conducted during the Mediterranean wide trawl (MEDITS) survey from 1994-1999 (Baino et al. 2001). Its overall biomass was estimated to be 0.6kg/km², with a higher presence in the eastern central Mediterranean area (Adriatic, Ionian sea and Albania: 1.2 kg/km²). The GRUND project (1985-1998), a series of experimental trawl surveys carried out on the continental and upper slopes of the central Mediterranean, reported 19.42% presence of this species in 22 surveys in Italian waters. Given percentage presence, this species was the 18th most common species, with the first and second most common species being Galeus melastomus and Scyliorhinus canicula (respectively 84.30% and 83.88% presence in trawls (Relini et al. 2000)).
No accurate data on population size is available for the Northeast Atlantic, although S. stellaris tends to be caught in low numbers only during trawl surveys. The population may be fragmented, as there are certain areas where they are most abundant. This species is rarely recorded in trawl surveys over finer sediments of the continental shelf, and tends to concentrate on coarse, inshore habitats. Around the British Isles, such areas occur along the coastline of Wales (Anglesey, Lleyn Peninsula, Cardigan Bay, Pembrokeshire, Gower), south-western England (Devon and Cornwall) and also off the French coast (Brittany).
|Habitat and Ecology:||
This species is found at depths of 1?2 m to at least 125 m, but is commonest in depths of 20?63 m (Compagno in prep.) or 20?150 m with a maximum depth of 400 m (Bauchot 1987, Serena, 2005). Within the northern Tyrrhenian and southern Ligurian sea, S. stellaris is distributed from 55?409 m depth (Baino and Serena 2000). It often occurs on rough or even rocky bottom or surfaces with algal cover and in the Mediterranean it is apparently prefers coralline algal substrates (Compagno in prep.).
The maximum reported size for S. stellaris in the Mediterranean is 150 cm (TL), and with a common range of 40?55 cm (TL) (Bauchot 1987). Adults are common to 125 cm (Compagno in prep.). Males mature at 77 cm total length (TL) and females at 79 cm TL (Bauchot 1987).
This is an oviparous species, with a single egg laid at a time per oviduct (Compagno in prep.). The large thick-walled egg-cases (10-13cm long with strong tendrils at each corner) are deposited on algae in the subtidal or extreme lower intertidal zone in spring and summer (Compagno in prep.). Once the eggs are deposited they take up to nine months to hatch (Compagno in prep.) with hatchlings measuring 10?16 cm at birth (Tortonese 1956, Bauchot 1987, Compagno in prep.). Egg-cases are often laid on macro-algae in inshore areas (Ellis et al. 2005a).
The diet of S. stellaris mostly consists of crustaceans (including hermit crabs, swimming crabs, cancrid crabs and large shrimp), squid, octopi and other molluscs, a variety of bony fish (including mackerel, epigonids, dragonets, gurnards, flatfish, herring, small codfish and other demersal fishes) and other sharks (including Scyliorhinus canicula). Along the Tunisian coasts, S. stellaris is also reported to feed on cephalopods, teleosts and crustaceans (Capapé 1975). There was no seasonal variation observed in the diet of S. stellaris, however adults (both males and females) fed on more cephalopods and teleosts, and less crustaceans in comparison to that of juveniles (Capapé 1975, Ellis et al. 1996).
Overfishing, together with habitat degradation, seem to be the major factors responsible for the decline of S. stellaris in the Mediterranean region. In addition, the capacity for population recovery of this species is affected by a low level of interconnectivity between isolated populations around islands far from the continental coast. The true extent of the impacts of fisheries on S. stellaris populations throughout the Mediterranean is difficult to evaluate, partly due to the lack of species-specific reports. In many areas, for example the Balearic Islands fishery and in Italian waters, S. stellaris is reported together with S. canicula or even as ?elasmobranchs?.
Taken as bycatch of the semi-industrial fisheries of Spain, the Adriatic Sea, Sicily and Cyprus and also in artisanal fisheries elsewhere and is regularly present in fish markets in Malta, Tunisia, Greece, Cyprus and Turkey (Compagno in prep.). In European waters, S. stellaris is less important as a fisheries species than S. canicula, but is regularly taken in bottom trawls, gill nets, bottom set long lines, handlines and fixed bottom nets, and occasionally pelagic trawls (Bauchot 1987, Compagno in prep.).
Benthic trawl effort has increased both numerically and in technological terms in the shelf and slope area of the Mediterranean over the last 50 years. For example, effort in trawl fisheries in the Gulf of Lions (NW Mediterranean) evolved from a small low powered fleet (total nominal horse power of 2, 700), increasing to a total nominal horse power of 19,940 hp (1974?1987). In a study of the long-term changes in groundfish diversity in the Gulf of Lions, Aldebert (1997) reports that there was a clear decrease in the abundance of this species since 1970. It was present in catches from the late 1950s to the 1980s and then disappeared from the catches after 1988 Aldebert (1997). Although not abundant, it seems that S. stellaris stocks have decreased in the Mediterranean.
A decline also seems to have occurred around Albania and the Balearic Islands: S. stellaris was frequently caught as bycatch by the bottom long-line and lobster fisheries, but catch numbers have decreased despite no change in the lobster fishing effort and equipment (G. Morey pers. obs.). Also of some concern is that the Balearic population has little connection with other populations of S. stellaris due the species? limited dispersal capacity. In the Balearic Islands S. stellaris was monitored from 131 hauls made between 40?1,800 m depth from 1996?2001 (Massutí and Moranta 2003), and while Galeus melastomus and S. canicula showed the highest abundances of all the elasmobranch species, S. stellaris was absent. Additionally, no specimens of S. stellaris have been captured during 12 trammel net surveys carried out in the Balearic Islands between 2000 and 2003 (Morey et al. in press). Current captures for this species in the Balearic Islands are sporadic. Fishermen report the species as common about 15 years ago, and abundant in lobster gillnet fishery, but becoming very rare to date (G. Morey pers. obs.). Jardas (1984) classified the species as rare in the western half of the Adriatic Sea in 1984, although S. stellaris does appear in trawl surveys carried out in 1948 and 1998 (Jukic-Peladic et al. 2001).
In the northeast Atlantic abundance data are insufficient to ascertain the current status, though due to its large size and patchy distribution, it may be at risk of localised depletion.
|Conservation Actions:||This species is protected in six marine reserves around the Balearic Islands, but further monitoring and protection measures are encouraged throughout its range.|
|Citation:||Ellis, J., Serena, F., Mancusi, C., Haka, F., Morey, G., Guallart, J. & Schembri, T. 2009. Scyliorhinus stellaris. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 25 May 2013.|
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