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Wednesday, September 7, 2011

Spiny Dogfish

Beauty Of Animal | Spiny Dogfish | The spiny dogfish, dogfish, piked dogfish or mud shark, Squalus acanthias, is one of the best known of the spiny dogfish, which are members of the family are in the order Squalidae Squaliformes. Though these common names apply to different species, Squalus acanthias is distinguished by having two spines (one anterior to each dorsal fin) and lacks an anal fin. It occurs mainly in shallow waters and further offshore in most parts of the world, especially in temperate waters.
Morphology and behavior  Spiny Dogfish
The spiny dogfish has dorsal spines, no anal fin, and white spots along its back. The caudal fin is asymmetrical lobes, forming a tail heterocercal. The species name refers to two of the acanthias shark spines. These are used defensively. If caught, the shark can arch its back to pierce her captor. Glands at the base of the spines secrete a mild poison. Males mature around 11 years, growing to 80-100 cm (2.6 to 3.3 meters) in length, in adult women 18 to 21 years and are slightly larger than males, reaching 98.5 to 159 cm (3.23 to 5.2 ft). Both sexes are gray-brown in color and are counter shaded. Males are identified by a pair of ventral fins modified as sperm-transfer agencies, or "claspers". The man adds a rank in the female cloaca during copulation.
Scientific classification
Kingdom:     Animalia
Phylum:     Chordata
Class:         Chondrichthyes
Subclass:     Elasmobranchii
Order:         Squaliformes
Family:         Squalidae
Genus:         Squalus
Species:     S. acanthias

Reproduction is viviparous aplacental, formerly called ovoviviparity. Fertilization is internal. The man adds a rank in the female oviduct opening and injects the sperm along a groove on the dorsum of the branch is. Immediately after fertilization the eggs are surrounded by thin shells called "candles" with a candle usually around a few eggs. Mating takes place in the winter months with pregnancy lasting 22 to 24 months. Nests are between 2 and 11, but on average 6 or 7.
Commercial use Spiny Dogfish

Dogfish are caught for food in Europe, the United States, Canada, New Zealand and Chile. The meat is mainly in England, France, Benelux and Germany. The fins and tail fin are processed into needles and are used in less expensive versions of shark fin soup in Chinese cuisine. In England these and other dogfish are sold in fish and chip shops as "rock salmon" or "Huss", in France it is sold as "little salmon" (saumonette) and in Belgium and Germany are sold as "sea eel" (Conger and Seeaal, respectively). It is also used as fertilizer, liver, and pet food, and because of the availability, cartilage skull, and the manageable size, as a popular vertebrate dissection specimen, in both high schools and universities.
Conservation & Management Spiny Dogfish

Once the most common shark species in the world, the people of Squalus acanthias has decreased significantly. They are classified in the IUCN Red List of Threatened Species as vulnerable worldwide and seriously endangered in the Northeast Atlantic, have significant inventories in Europe fell by at least 95%. This is a direct result of overfishing to northern Europe to deliver a taste for Rock Salmon, Saumonette or conger. Despite these alarming numbers, very little management or conservation measures taken to Squalus acanthias. In EU waters, a total allowable catch (TAC) since 1999 but until 2007 only to ICES zones IIa and IV. It was also well above the actual weight of the fish is caught until 2005, making it useless. Currently (2009), the TAC is at 316t for ICES zones IIa and IV, 104t in ICES zone IIIa and 1,002 tonnes for ICES areas I, V - VIII, XII and XIV. In addition, a maximum of 100 cm landing of becoming the most valuable to protect adult females. The European Commission has stated that the TAC for 2010 will be determined on the 0t, ending direct fishing of the species in EU waters. It remains to be seen whether people will be able to recover.
In the recent past, the European market for dogfish has increased dramatically, leading to overfishing and the decline of the species. This dramatic increase led to the creation and implementation of many fisheries policies placing restrictions on fishing for spiny dogfish. However, because the species is a late adult fish, it takes a while to rebuild the population. In 2010, Greenpeace International added to the spiny dogfish seafood red list. "The Greenpeace International seafood red list is a list of fish commonly sold in supermarkets around the world, and a very high risk to be coming from unsustainable fishing

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