Mustelus Asterias

– Starry Smooth-Hound –

The starry smooth-hound (Mustelus asterias) is a houndshark of the family Triakidae. It is found on the continental shelves of the northeast Atlantic, between latitudes 61° N and 16° N, from the surface to a depth of 200 m (660 ft). It can grow up to a length of 1.4 m (4 ft 7 in).

Description

The starry smooth-hound grows to a length of about 140 cm (55 in). It is grey or greyish-brown with a scattering of small white spots on its dorsal (upper) surface and white on its ventral (under) surface.

With a thin and very elongated body , the common dogfish reaches a length of between 1.40 m and, at most, 1.60 m long; the common size is between 0.80 m and 1.20 m. Its color varies from brown-gray to slate gray or mouse gray with the presence of white spots variously placed on the dorsal zone and along the lateral line . On the skin, are arranged tricuspid cutaneous denticles (with three points), with four keels (small longitudinal reliefs) well apart. A small vent opens behind each eye, which also has a nictitating membrane *; we also note the presence of two nostrils close together .

Mustelus asterias has a wide mouth , almost extending beyond the rear eye level.
The dental formula of the speckled emissole is quite simple: 40-40 / 40-40 (ie, here, an identical number of teeth per half-jaw – upper part – and per half-mandible – lower part -). The upper teeth are very small, with a low cusp *; they form a pavement structure * (in the form of a paving stone). The lower teeth appear to be comparable. In newborns, we note the presence of very small accessory cusps.

We note, as with many sharks, the presence of five gill slits.
In addition to two dorsal fins, the animal has a strongly asymmetrical caudal blade with a large terminal lobe.

Distribution and Habitat

This species of houndshark is found in the eastern Atlantic Ocean and the Mediterranean Sea. Its range extends from southern Norway, Scotland, and the North Sea southwards to Algeria, Morocco, and Western Sahara. It is found in the whole of the Mediterranean, but not in the Black Sea.^[1] It is found on the continental shelf and around islands at depths to at least 200 m (660 ft) and prefers places where the seabed is sand or gravel.^[4]

Biotope

The starry smoothhound appreciates the vaso-sandy and detrital bottoms of the continental shelf, from 5 to 10 m down to a depth of 100 to 180 m, but in the Canary Islands, it is still found at 350 m depth; it can frequent more coastal waters, especially at night.

Similar Species

The differences are minimal:

• The common smooth-hound Mustelus mustelus (Linné, 1758) is distinguished by a livery without spots; its average height is 75 cm. Living near the bottom, the smooth emissole is always found near the coast but, at depth, is found up to 350 m. She sometimes ventures into the open water.
• The black spotted hound Mustelus punctulatus (Risso, 1827), whose invalid synonym is Mustelus mediterraneus (Quignard & Capapé, 1972), also present in the North-East Atlantic and in the Mediterranean, hardly reaches a size greater than 95 cm. Its dorsal coloration varies from light gray to gray-brown, with a clear belly (white, quite often) and it has no spots.
• The Tope Shark or Galeorhinus galeus (Linnaeus, 1758) is a “dogfish” with a wider distribution, ranging from north of the Arctic Circle to Cape Horn. Its livery, also in the gray scale, does not show any stains. The young have more easily blackish markings on the fins.

Associated Life

Mustelus asterias lives easily in small groups, without distinction of age classes. It also seems to coexist with sharks ha (Galeorhinus galeus ) and smooth emissoles.

In terms of parasitism, the copepod Lernaeopoda galei (Kroyer, 1837) likes the cloacal region of the spotted emissole (and also attaches to other selachians, such as the eagle ray Myliobatis aquila ).

Various Biology

Mustelus asterias does not tolerate water temperature below 16 ° C and would tend to approach the coast in summer, undertaking small migrations over 50 to 100 km.

Rather abundant target species, Mustelus asterias is not currently the victim of overexploitation in European waters (cf. Regulations: LC classification). The case remains rare enough to merit reporting (comm. B. Séret): an increase in their abundance has been noted since 1990. French production represents around 60% at European level, with 1,800 tonnes recorded in 2007 ( Mustelus asterias and M. musteluscombined). This resistance can be explained by fairly high productivity (ICES report, 2008) and no doubt also by other exogenous factors.

This shark is said to be the most common of the three emissoles present in European waters.

It is nevertheless important to monitor the numbers of Mustelus asterias , due to the excessive pressure that commercial fishing generally exerts on sharks. Mustelus asterias belongs to this category of fish marketed in the fishmonger’s stall under the generic term of “salmon”.

Biology

The starry smooth-hound mostly feeds on crustaceans, such as crabs, lobsters, and slipper lobsters, and molluscs. It matures at a length of about 80 to 85 cm (31 to 33 in). It is an ovoviviparous fish, retaining its eggs in its oviduct where the young are nourished by the egg yolk and the oviduct’s secretions. Seven to 15 young are in a litter, and they are about 30 cm (12 in) long at birth.^[3][4]

Alimentation

Scientific work on the diet of the spotted emissole remains scarce.

More active at night than during the day, Mustelus asterias has the reputation of a crab-eating fish and actually feeds mainly on crustaceans. The latter represent 60 to 97% of its prey (in the Irish Sea, for the highest figure), with a preferential diet for crabs – of the Genus Liocarcinus – and pagures but also curries, langoustines, lobsters, lobsters, shrimps …, cephalopods – cuttlefish, squid – (20%), molluscs and even lugworms or sea anemones …

Adult, the spotted emissole diversifies its diet more, appreciating more readily the consumption of bony fish (20%): herrings, sardines and other clupeids, brown mullet, horse mackerel and mackerel, pleuronects and other flatfish, gobies and small rock fish. ..

Reproduction

The sexual maturity of the spotted emissole becomes effective at the age of 2 or 3 years. In males, the size is then between 75 and 87 cm and, in females, between 85 and 96 cm. The gestation period lasts about twelve months.

The species is viviparous * aplacental * (whereas the smooth emissole Mustelus mustelus is strictly oviparous *) with an apparently very variable number of fetuses, between six and thirty (some authors even put forward the figure of sixty). The average could be around twenty cubs. Ultimately, the size of Mustelus asterias is around 28.5 to 30 cm.

In the Mediterranean, the Gulf of Lion and the Adriatic Sea constitute recorded breeding areas.

Status

The IUCN, in its Red List of Threatened Species lists the starry smooth-hound as “Least Concern“. The justification for this is that it has a wide range and is common in the northern part of its range where its population seems to be steady. In the Mediterranean Sea, it is less common and is targeted for human consumption along with the closely related common smooth-hound (Mustelus mustelus).^[1] Numbers in the Mediterranean have dwindled and in this region it might qualify for “Vulnerable” status were it not plentiful elsewhere.^[1]

FURTHER INFORMATION

This small shark, like fruit bats ( Scyliorhinus canicula and S. stellaris ), is completely harmless to humans.