Scyliorhinus stellaris (Linnaeus, 1758)
Aegean Sea : 600-584 (1 spc.), August 2000 , Bozcaada Island , trammel net , 30 m, L. Eryilmaz ; 600-581 (1 spc.), 07.06.2001 , Bozcaada Island , trammel net , 5 m, L. Eryilmaz .
- Nurettin Meriç, Lütfiye Eryilmaz, Müfit Özulug (2007): A catalogue of the fishes held in the Istanbul University, Science Faculty, Hydrobiology Museum. Zootaxa 1472, 29-54: 31-31, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:428F3980-C1B8-45FF-812E-0F4847AF6786
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.
Body shape lateral: elongated
Cross section: compressed
Type of eyes: more or less normal
Type of mouth/snout: more or less normal
Position of mouth: sub-terminal/inferior
Diagnosis: A large, fairly stocky, catshark with large and small black spots and sometimes white spots covering dorsal surface, saddle markings obsolete, small anterior nasal flaps that do not reach the mouth, no nasoral grooves, labial furrows on lower jaw only, second dorsal fin much smaller than first.
Lateral Lines: Interrupted: No
Gill clefts (sharks/rays only): 5
Fins number: 2
Finlets No.: Dorsal 0 – 0, Ventral 0 - 0
Spines total: 0 - 0
Soft-rays total: 0 - 0
Adipose fin: absent
Habitat and Ecology
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).
Water temperature and chemistry ranges based on 54 samples.
Depth range (m): 1 - 160
Temperature range (°C): 8.316 - 19.273
Nitrate (umol/L): 0.756 - 22.947
Salinity (PPS): 34.250 - 37.656
Oxygen (ml/l): 1.655 - 6.265
Phosphate (umol/l): 0.115 - 1.554
Silicate (umol/l): 2.210 - 11.058
Depth range (m): 1 - 160
Temperature range (°C): 8.316 - 19.273
Nitrate (umol/L): 0.756 - 22.947
Salinity (PPS): 34.250 - 37.656
Oxygen (ml/l): 1.655 - 6.265
Phosphate (umol/l): 0.115 - 1.554
Silicate (umol/l): 2.210 - 11.058
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
From 1 to 400 meters.
Life History and Behavior
Lifespan, longevity, and ageing
Evolution and Systematics
Molecular Biology and Genetics
Barcode data: Scyliorhinus stellaris
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Scyliorhinus stellaris
Public Records: 5
Specimens with Barcodes: 12
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
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).
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.
Relevance to Humans and Ecosystems
The nursehound (Scyliorhinus stellaris), also known as the large-spotted dogfish, greater spotted dogfish, or bull huss, is a species of catshark, belonging to the family Scyliorhinidae, found in the northeastern Atlantic Ocean. It is generally found among rocks or algae at a depth of 20–60 m (66–197 ft). Growing up to 1.6 m (5.2 ft) long, the nursehound has a robust body with a broad, rounded head and two dorsal fins placed far back. It shares its range with the more common and closely related small-spotted catshark (S. canicula), which it resembles in appearance but can be distinguished from, in having larger spots and nasal skin flaps that do not extend to the mouth.
Nursehounds have nocturnal habits and generally hide inside small holes during the day, often associating with other members of its species. A benthic predator, it feeds on a range of bony fishes, smaller sharks, crustaceans, and cephalopods. Like other catsharks, the nursehound is oviparous in reproduction. Females deposit large, thick-walled egg cases, two at a time, from March to October, securing them to bunches of seaweed. The eggs take 7–12 months to hatch. Nursehounds are marketed as food in several European countries under various names, including "flake", "catfish", "rock eel", and "rock salmon". It was once also valued for its rough skin (called "rubskin"), which was used as an abrasive. The International Union for Conservation of Nature (IUCN) has assessed the nursehound as Near Threatened, as its population in the Mediterranean Sea seems to have declined substantially from overfishing.
The first scientific description of the nursehound was published by Carl Linnaeus, in the 1758 tenth edition of Systema Naturae. He gave it the name Squalus stellaris, the specific epithet stellaris being Latin for "starry". No type specimen was designated. In 1973, Stewart Springer moved this species to the genus Scyliorhinus. The common name "nursehound" came from an old belief by English fishermen that this shark attends to its smaller relatives, while the name "huss" may have come from a distortion of the word "nurse" over time.
Distribution and habitat
The nursehound is found in the northeastern Atlantic from southern Norway and Sweden to Senegal, including off the British Isles, throughout the Mediterranean Sea, and the Canary Islands. It may occur as far south as the mouth of the Congo River, though these West African records may represent misidentifications of the West African catshark (S. cervigoni). Its range seems to be rather patchy, particularly around offshore islands, where there are small local populations with limited exchange between them. The nursehound can be found from the intertidal zone to a depth of 400 m (1,300 ft), though it is most common between 20 m (66 ft) and 60–125 m (197–410 ft). This bottom-dwelling species prefers quiet water over rough or rocky terrain, including sites with algal cover. In the Mediterranean, it favors algae-covered coral.
The nursehound attains a length of 1.6 m (5.2 ft), though most measure less than 1.3 m (4.3 ft). This shark has a broad, rounded head and a stout body that tapers towards the tail. The eyes are oval in shape, with a thick fold of skin on the lower rim but no nictitating membrane. Unlike in the small-spotted catshark, the large flaps of skin beside the nares do not reach the mouth. In the upper jaw, there are 22–27 tooth rows on either side and 0–2 teeth at the symphysis (center); in the lower jaw, there are 18–21 tooth rows on either side and 2–4 teeth at the symphysis. The teeth are Y-shaped and smooth-edged; the anterior teeth have a single central cusp, while the posterior teeth have an additional pair of lateral cusplets. Towards the rear of the jaws, the teeth become progressively smaller and more angled, with proportionately larger lateral cusplets. The five pairs of gill slits are small, with the last two over the pectoral fin bases.
The two dorsal fins are placed far back on the body; the first is larger than the second and originates over the bases of the pelvic fins. The pectoral fins are large. In males, the inner margins of the pelvic fins are merged into an "apron" over the claspers. The caudal fin is broad and nearly horizontal, with an indistinct lower lobe. The skin is very rough, due to a covering of large, upright dermal denticles. The nursehound has small black dots covering its back and sides, interspersed with brown spots of varying shapes larger than the pupil, on a grayish or brownish background. The pattern is highly variable across individuals and ages; there may also be white spots, or the brown spots may be expanded so that almost the whole body is dark, or a series of faint "saddles" may be present. The underside is plain white.
Biology and ecology
Primarily nocturnal, nursehounds spend the day inside small holes in rocks and swim into deeper water at night to hunt. Sometimes two sharks will squeeze into the same hole, and several individuals will seek out refuges within the same local area. In one tracking study, a single immature nursehound was observed to use five different refuges in succession over a period of 168 days, consistently returning to each one over a number of days before moving on. Nursehounds may occupy refuges to hide from predators, avoid harassment by mature conspecifics, and/or to facilitate thermoregulation. In captivity, these sharks are gregarious and tend to rest in groups, though the individuals comprising any particular group changes frequently. This species is less common than the small-spotted catshark.
The nursehound feeds on a variety of benthic organisms, including bony fishes such mackerel, deepwater cardinalfishes, dragonets, gurnards, flatfishes, and herring, and smaller sharks such as the small-spotted catshark. It also consumes crustaceans, in particular crabs but also hermit crabs and large shrimp, and cephalopods. Given the opportunity, this shark will scavenge. Adults consume relatively more bony fish and cephalopods, and fewer crustaceans, than juveniles. Known parasites of this species include the monogeneans Hexabothrium appendiculatum and Leptocotyle major, the tapeworm Acanthobothrium coronatum, the trypanosome Trypanosoma scyllii, the isopod Ceratothoa oxyrrhynchaena, and the copepod Lernaeopoda galei. The netted dog whelk (Nassarius reticulatus) preys on the nursehound's eggs by piercing the case and extracting the yolk.
Like other members of its family, the nursehound is oviparous. Known breeding grounds include the River Fal estuary and Wembury Bay in England, and a number of coastal sites around the Italian Peninsula, in particular the Santa Croce Bank in the Gulf of Naples. Adults move into shallow water in the spring or early summer, and mate only at night. The eggs are deposited in the shallows from March to October. Although a single female produces 77–109 oocytes per year, not all of these are ovulated and estimates of the actual number of eggs laid range from 9 to 41. The eggs mature and are released two at a time, one from each oviduct. Each egg is enclosed in a thick, dark brown case measuring 10–13 cm (3.9–5.1 in) long and 3.5 cm (1.4 in) wide. There are tendrils at the four corners, that allow the female to secure the egg cases to bunches of seaweed (usually Cystoseira spp. or Laminaria saccharina).
Eggs in the North Sea and the Atlantic take 10–12 months to hatch, while those from the southern Mediterranean take 7 months to hatch. The length at hatching is 16 cm (6.3 in) off Britain, and 10–12 cm (3.9–4.7 in) off France. Newly hatched sharks grow at a rate of 0.45–0.56 mm (0.018–0.022 in) per day, and have prominent saddle markings. Sexual maturity is attained at a length of 77–79 cm (30–31 in), which corresponds to an age of four years if hatchling growth rates remain constant. This species has a lifespan of at least 19 years.
Nursehounds are generally harmless to humans. However, 19th-century British naturalist Jonathan Couch noted that "although not so formidable with its teeth as many other sharks, this fish is well able to defend itself from an enemy. When seized it throws its body round the arm that holds it, and by a contractile and reversed action of its body grates over the surface of its enemy with the rugged spines of its skin, like a rasp. There are few animals that can bear so severe an infliction, by which their surface is torn with lacerated wounds." This shark is displayed by many public aquariums and has been bred in captivity.
The rough skin (called "rubskin") of the nursehound was once used to polish wood and alabaster, to smooth arrows and barrels, and to raise the hairs of beaver hats as a replacement for pumice. Rubskin was so valued that a pound of it was worth a hundredweight of sandpaper. The liver was also used as a source of oil, and the carcasses cut up and used to bait crab traps. The meat of this species is marketed fresh or dried and salted, though it is considered "coarse" in some quarters. In the United Kingdom (UK), it is one of the species sold under the names "flake", "catfish", "rock eel", or "rock salmon". In France, it is sold as grande rousette or saumonette, as after being skinned and beheaded it resembles salmon. This species is also sometimes processed into fishmeal, or its fins dried and exported to the Asian market. In European waters, commercial production of this species is led by France, followed by the UK and Portugal; it is caught using bottom trawls, gillnets, bottom set longlines, handlines and fixed bottom nets. In 2004, a total catch of 208 tons was reported from the northeastern Atlantic.
The impact of fishing activities on the nursehound is difficult to assess as species-specific data is generally lacking. This species is more susceptible to overfishing than the small-spotted catshark because of its larger size and fragmented distribution, which limits the recovery potential of depleted local stocks. There is evidence that its numbers have declined significantly in the Gulf of Lion, off Albania, and around the Balearic Islands. In the upper Tyrrhenian Sea, its numbers have fallen by over 99% since the 1970s. These declines have led the International Union for Conservation of Nature (IUCN) to list the nursehound under Near Threatened.
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