Large spotted dogfish

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Large spotted dogfish
Great spotted dogfish (Scyliorhinus stellaris)

Great spotted dogfish ( Scyliorhinus stellaris )

Systematics
without rank: Sharks (selachii)
Superordinate : Galeomorphii
Order : Ground Sharks (Carcharhiniformes)
Family : Cat sharks (Scyliorhinidae)
Genre : Scyliorhinus
Type : Large spotted dogfish
Scientific name
Scyliorhinus stellaris
( Linnaeus , 1758)

The Großgefleckte dogfish or Large dogfish ( Scyliorhinus stellaris ) is a species of shark from the family of dogfish (Scyliorhinidae). It lives in the eastern Atlantic on the coasts of Europe and North Africa, as well as in the Mediterranean, and is usually found over rocky ground at depths of 20 to 60 meters. It occurs in large parts of its distribution area together with the small-spotted dogfish ( S. canicula ), from which it differs through a pattern of larger spots.

The shark reaches an average body length of about 1.3 meters and can be a maximum of 1.6 meters long. It is nocturnal and usually spends the day hidden in caves or lying on the ocean floor. It feeds mainly on bottom-living fish, smaller sharks and invertebrates. Like other cat sharks, it is egg-laying, with the female laying thick-walled eggs with long strings attached to seaweed. In large parts of Europe, the great spotted dogfish is commercially fished and marketed as food fish. It is harmless to humans and is included in the Red List of Endangered Species of the International Union for Conservation of Nature (IUCN) as a type of warning list.

features

Large-spotted dogfish in a public aquarium

Large-spotted cat sharks have the elongated, very slender body of all cat sharks, which tapers towards the tail. Compared to other types of the family, however, they are relatively sturdy, with a pronounced back. They usually reach a length of about 1.30 meters in the Atlantic, but can also be over 1.60 meters long. In the Mediterranean, the sharks only reach an average length of 0.75 meters, the longest animal caught here was a 1.08 meter long male. The body is gray-brown in color and has numerous small and large black spots, which are often irregular and partially overlap, creating a leopard-like pattern. The drawing is very variable and some individuals also have white dots or large, extensive saddle marks that cover large parts of the body. The ventral side is white. The pectoral fins are gray-brown and spotted on the underside, with the dots turning white towards the base of the fin.

Tooth shapes in the large-spotted dogfish

The head is moderately broad with a flattened muzzle and large, oval-shaped eyes. A thick fold of skin is formed at the lower edge of the eyes, a nictitating membrane is missing. The nasal pits are large; the clearly developed skin flaps of the nose (nasal flaps), in contrast to those of the small-spotted cat shark, do not meet in front of the mouth. The teeth are Y-shaped and their edges are smooth. The front teeth only have a narrow and straight main point, while the rear teeth become smaller and additionally have a pair of relatively larger side points. In the upper jaw there are 22 to 27 teeth on each side as well as 0 to 2 teeth in the area of ​​the symphysis between the jaw halves, in the lower jaw 18 to 21 and 2 to 4 in the area of ​​the symphysis.

The suction holes behind the eyes are medium-sized, the five gill slits short, with the last two above the base of the broad and short pectoral fins . The two dorsal fins are small and lie far back on the body, the front one is larger and attaches over the pelvic fins ; the rear, somewhat smaller, clearly behind the base of the relatively long anal fin . The pectoral fins are large, the males' ventral fins form an "apron" that has grown together above the clasps . The caudal fin is broad and conspicuously unevenly forked ( heterocerk ), with a long upper and short lower lobe and a long end lobe. The skin surface of the great spotted cat shark is very rough due to the relatively large, partially erect placoid scales .

distribution and habitat

Distribution areas of the great spotted cat shark

The range of the species includes the Mediterranean and the shelf areas of the east Atlantic from southern Scandinavia over the British Isles and the European Atlantic coast as well as the area of ​​the Canary Islands to Senegal . Possibly it extends further to the mouth of the Congo , whereby corresponding sightings can also be due to confusion with the West African dogfish ( S. cervigoni ).

The preferred water depth is 20 to 63 meters, the maximum populated depth up to 125 meters. Preference is given to calm sea coasts with rough to rocky subsoil, often with algae or coral growth. In the Mediterranean, the species prefers biotopes with algae and corals.

Way of life

Large-spotted cat sharks are predominantly nocturnal bottom dwellers who live solitary or in large schools, sometimes divided according to body size. During the day they rest on the bottom, often pushing themselves up with their pectoral fins in order to take in more water to breathe through the suction holes, or often to several individuals in small caves. In one study it was observed that a single, immature shark used five different refuges in a row within 168 days, visiting each one for a few days and then moving on. The sharks use these places of refuge to hide from predators, to avoid harassment by mature members of the species and to facilitate thermoregulation . When hunting, they often swim into deeper water layers at night.

In captivity, great spotted cat sharks are gregarious and typically rest in groups, with their makeup changing frequently. The species is less common than the small spotted dogfish ( S. canicula ).

nutrition

The food is mainly living on the ground, i.e. various crustaceans such as crabs , hermit crabs and large shrimps , but also molluscs , echinoderms , various worms and smaller bony fish and sharks. He preyed on mackerel , herrings , flatfish , gurnards , lyrefish and deep-sea cardinalfish as well as smaller sharks such as the small spotted dogfish ( S. canicula ). In addition, this shark is known as a scavenger .

Parasites

Among the known parasites of Großgefleckten dogfish belonging flatworms Hexabothrium appendiculatum and Leptocotyle major , the tapeworm Acanthobothrium coronatum which the trypanosomes belonging Trypanosoma scyllii that Assel Ceratothoa oxyrrhynchaena , and the copepod Lernaeopoda galei . The sea snail Nassarius reticulatus feeds on the eggs of the dogfish by pricking them and sucking out the yolk.

Reproduction

Great-spotted cat shark eggs in an aquarium; some had the cover opened to reveal the embryo

Like other cat sharks, the large-spotted cat shark is also oviparous . The sharks meet in shallow water for night mating in spring and early summer. To lay their eggs, the females seek breeding grounds in shallow water in May to October. Well-known breeding grounds are the river delta of the River Fal and Wembury Bay in England . Although females produce 77 to 109 eggs per year, not all of them are shed. Estimates of the actual laying rates are between 9 and 41 eggs per female and egg laying time. The eggs mature in the paired fallopian tubes and are accordingly deposited in pairs. The approximately 10 to 13 centimeters long and 3.5 centimeters wide egg capsules are encased in a thick, brown egg shell and have long holding threads at all four corners with which they can be found between algae and seaweed , especially Cystoseira spp. or Laminaria saccharina .

The young cats of the great spotted cat shark have distinct saddle spots

In the North Sea and the Atlantic Ocean, juvenile sharks take 10 to 12 months to develop in the eggs, in the southern Mediterranean only 7 months. When hatching, the young are about 16 centimeters from Great Britain, but only 10 to 12 centimeters from France. The young sharks initially grow about 0.45 to 0.56 millimeters a day and have noticeable saddle spots. The sexual maturity is achieved with a length of about 77 to 79 centimeters, and the age of about four years. The documented maximum age is 19 years.

Systematics

The first scientific description of the great spotted cat shark was made in 1758 by Carl von Linné in his 10th edition of the Systema Naturae . He named it as Squalus stellaris , the type epithet being derived from the Latin term stellaris for "star". Linnaeus did not name any type . In 1973 the shark was transferred to the genus Scyliorhinus by Stewart Springer , which today consists of 14 species.

Relationship to people

The species is harmless to humans. If it is caught, however, it can defend itself and, above all, cause wounds through its rough skin. The British naturalist Jonathan Couch wrote in 1868: “Even if not as terribly with the teeth as many other sharks, this fish is quite capable of defending itself from an enemy. When caught, he wraps his body around the arm that holds him and, by twisting his body, rubs the hard spikes of his skin across the surface like a rasp. There are only a few animals that can inflict such severe lacerations on their enemies. ”The shark is kept in numerous aquariums around the world and is also successfully reproduced.

The great spotted dogfish is of great economic importance in the region and is caught with ground nets and eaten fresh or salted or processed into fish meal . In Great Britain the shark is marketed under the names “flake”, “catfish”, “rock eel” or “rock salmon”, while in France it is sold as “grande roussette” or “saumonette”. The fins are dried and exported to the Asian market for shark fin soup . The rough skin of the great spotted cat shark ("rubskin") was formerly used as sandpaper for processing wood, especially for wooden barrels, and alabaster , and as a substitute for pumice for processing castor hats and was about the value of a hundred weight (around 50 kilos) Sandpaper . The liver was used to make liver oil and the rest of the body was used as bait for cancer traps. Most commercial catches of the great spotted cat shark in Europe come from France, followed by Great Britain and Portugal. Ground trawls or gill nets are used for this. For the year 2004 a total catch of this species of 208 tons from the North Atlantic was documented.

In the Red List of the International Union for Conservation of Nature (IUCN) the great spotted dogfish is listed as a type of the warning list ("Near Threatened"). This classification is justified primarily with the local decline in some areas in the Mediterranean and the British Isles as well as with the patchy distribution with only a low population exchange of the species and is based on a very thin database, which is why a future classification as endangered ) is not excluded. In the Upper Tyrrhenian Sea , stocks have declined by 99% since the 1970s.

supporting documents

  1. ↑ a b c d e Alessandro de Maddalena, Harald Bänsch: Sharks in the Mediterranean. Franckh-Kosmos, Stuttgart 2005, pp. 161-163. ISBN 3-440-10458-3
  2. ↑ a b c d Compagno, LJV, Dando, M. and Fowler, S .: Sharks of the World . Princeton University Press, 2005, ISBN 9780691120720 , p. 252.
  3. ↑ a b Kuno Sch. Steuben : The sharks of the seven seas: species, way of life and sporting catch. Parey, Berlin 1989; Pages 77–78. ISBN 3-490-44314-4
  4. ↑ a b c d e f Lythgoe, J. and Lythgoe, G .: Fishes of the Sea: The North Atlantic and Mediterranean . MIT Press, 1992, ISBN 026212162X , p. 21.
  5. ↑ Soldo, A., Dulcic, J. and Cetinic, P .: Contribution to the study of the morphology of the teeth of the nurse and Scyliorhinus stellaris (Chondrichthyes: Scyliorhinidae) . In: Scientia Marina . 64, No. 3, 2000, pp. 355-356.
  6. ↑ a b c d e f Compagno, LJV: Sharks of the World: An Annotated and Illustrated Catalog of Shark Species Known to Date . Food and Agricultural Organization, Rome 1984, ISBN 9251013845 , pp. 366-367.
  7. ↑ Sims, DW, Southall, EJ, Wearmouth, VJ, Hutchinson, N., Budd, GC and Morritt, D .: Refuging behavior in the nursehound Scyliorhinus stellaris (Chondrichthyes: Elasmobranchii): preliminary evidence from acoustic telemetry . In: Journal of the Marine Biological Association of the United Kingdom . 85, 2005, pp. 1137-1140. doi : 10.1017 / S0025315405012191 .
  8. ↑ a b Scott, GW, Gibbs, K. and Holding, J .: Group 'resting' behavior in a population of captive bull huss ( Scyliorhinus stellaris ) . In: Aquarium Sciences and Conservation . 1, 1997, pp. 251-254.
  9. ↑ a b c Ford, E .: A contribution to our knowledge of the life histories of the dogfishes landed at Plymouth . In: Journal of the Marine Biological Association of the United Kingdom . 12, 1921, pp. 468-505. doi : 10.1017 / S0025315400006317 .
  10. ↑ Kearn, GC: Leeches, Lice and Lampreys: A Natural History of Skin and Gill Parasites of Fishes . Springer, 2004, ISBN 140202925X , p. 104.
  11. ↑ Llewellyn, J., Green, JE and Kearn, GC: A check-list of monogenean (Platyhelminth) parasites of Plymouth hosts . In: Journal of the Marine Biological Association of the United Kingdom . 64, 1984, pp. 881-887. doi : 10.1017 / S0025315400047299 .
  12. ↑ Williams, HH and Jones, A .: Parasitic Worms of Fish . CRC Press, 1994, ISBN 085066425X , p. 336.
  13. ↑ pulse Ford, A .: Preliminary studies on trypanospmes from the dogfish, Scyliorhinus canicula L. . In: Journal of Fish Biology . 24, No. 6, 1983, pp. 671-682. doi : 10.1111 / j.1095-8649.1984.tb04838.x .
  14. ↑ Ramdane, Z., Bensouilah, MA and Trilles, JP: The Cymothoidae (Crustacea, Isopoda), parasites on marine fishes, from Algerian fauna . In: Belgian Journal of Zoology . 137, No. 1, 2007, pp. 67-74.
  15. ↑ Karaytug, S., Sak, S. and Alper, A .: Parasitic Copepod Lernaeopoda galei Krøyer, 1837 (Copepoda: Siphonostomatoida): A First Record from Turkish Seas . In: Turkish Journal of Zoology . 28, 2004, pp. 123-128.
  16. ↑ a b c Orton, JH: A Breeding Ground of the Nursehound ( Scyliorhinus stellaris ) in the Fal Estuary . In: Nature . 118, 1926, p. 732.
  17. ↑ a b c Capapé, C., Vergne, Y., Vianet, R., Guélorget, O. and Quignard, J .: Biological observations on the nursehound, Scyliorhinus stellaris (Linnaeus, 1758) (Chondrichthyes: Scyliorhinidae) in captivity . In: Acta Adriatica . 47, No. 1, 2006, pp. 29-36.
  18. ^ Longevity, aging, and life history of Scyliorhinus stellaris . AnAge: The Animal Aging and Longevity Database. Accessed June 21, 2010.
  19. ↑ Squalus stellaris  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. . (2007). Catalog of Fishes . California Academy of Sciences.@1@ 2Template: Dead Link / research.calacademy.org  
  20. ↑ a b Large spotted dogfish on Fishbase.org (English)
  21. ↑ "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. " In: Couch, J .: A History of the Fishes of the British Islands . Groombridge and Sons, 1868, pp. 11-12.
  22. ↑ a b c Day, F .: The Fishes of Great Britain and Ireland . Williams and Norgate, 1884, pp. 312-313.
  23. ↑ Davidson, A .: Mediterranean Seafood: A Comprehensive Guide with Recipes , third. Edition, Ten Speed ​​Press, 2002, ISBN 1580084516 , p. 28.
  24. ↑ Davidson, A .: North Atlantic Seafood: A Comprehensive Guide with Recipes , third. Edition, Ten Speed ​​Press, 2004, ISBN 1580084508 , p. 168.
  25. ^ Vannuccini, S .: Shark Utilization, Marketing and Trade . Food and Agriculture Organization of the United Nations, 1999, ISBN 9251043612 , pp. 175-176.
  26. ^ Yaxley, D .: A Researcher's Glossary of Words Found in Historical Documents of East Anglia . Larks Press, 2003, ISBN 1904006132 , p. 107.
  27. ↑ FAO Yearbook [of] Fishery Statistics: Aquaculture Production, 2004 . Food and Agriculture Organization, 2006, ISBN 9250055196 , p. 436.
  28. ↑ a b Scyliorhinus stellaris in the IUCN Red List of Threatened Species 2010.1. Posted by: Ellis, J., Serena, F., Mancusi, C., Haka, F., Morey, G., Guallart, J. & Schembri, T., 2006. Retrieved June 20, 2010.
  29. ↑ Ferretti, F., Myers, RA, Sartor, P. and Serena, F. (2005). Long Term Dynamics of the Chondrichthyan Fish Community in the Upper Tyrrhenian Sea ( Memento of the original from April 1, 2011) Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 301 kB). ICES Council Meeting, 2005 / N: 25. @1@ 2Template: Webachiv / IABot / www.fmap.ca

literature

Web links

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