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Piked Dogfish

 

 

Piked Dogfish

 

 

  • PIKED DOGFISH

Scientific name.......Squalus Acanthias

Family name...........Squalidae

Common names..........Piked dogfish or Spiny dogfish

 

 

  • GENERAL DESCRIPTION

The Piked dogfish is also known as the Spiny dogfish. It is identified by a large spiracle behind each large eye, the presence of mildly poisonous spines on the two dorsal fins, and the lack of an anal fin. They have a narrow head, relatively a long, pointed snout and no medial barbel on anterior nasal flaps. Pectoral fins with shallowly concave posterior margins and narrowly rounded rear tips. First dorsal fin low, origin usually behind or sometimes over pectoral free rear tips, first dorsal spine slender and very short with origin well behind pectoral free rear tips.

 

  • SIZE

The average size of the piked dogfish is 4 to 5.2 feet. Size at birth is approximately 7.2 to 12 inches. Males mature at 3.2 feet and females at 3.9 feet.

 

  • TEETH

The upper and lower teeth are small, and similar in shape with oblique points bent toward the outer corners of the mouth. The cusps are deeply notched outward with a single sharp point. These form a nearly continuous cutting edge from one corner of the mouth to the other. There are 28 upper teeth and 22-24 lower teeth in the jaws of the piked dogfish.

 

  • COLOR

Their body is gray to a bluish-gray above, lighter to white below, often with white spots on sides; pectoral fins with light posterior margins in adults. dorsal fin tips and edges dusky or plain in adults, with black apices and white posterior margins and free rear tips in young; no conspicuous black blotches on fins.

 

  • FEEDING HABITS

Their diet includes small fishes, such as cod, herring, menhaden, and haddock, as well as invertebrates such as krill, squid, scallops, and crustaceans.

 

  • SOCIAL BEHAVIOUR

Mainly demersal ( occurring or living near or on the bottom of the ocean ), apparently also epipelagic, sometimes solitary or schooling with other small sharks, often forming immense dense feeding aggregation on rich feeding grounds. Segregates by size and sex into packs or schools of small juveniles ( both sexes ), mature males, larger immature females, or large mature females (often pregnant). Mixed adult schools occasionally reported.

 

  • HABITAT

Almost world-wide, except tropics and near poles. Little or no mixing between northern and southern hemisphere populations and limited genetic mixing between some stocks with overlapping range and feeding grounds but different migration patterns. Boreal to warm-temperate continental and insular shelves, occasionally slopes from surface to 1,968 feet and possibly as deep as 4,744 feet. Epipelagic from surface to 565 feet in cold water. Usually near bottom on continental shelf, near surface in oceanic waters. Often on soft sediments in enclosed and open bays and estuaries, where most nursery grounds occur.

 

  • LIFE SPAN

This species is extremely slow growing and can live for up to 70 - 100 years, varies between populations.

 

  • REPRODUCTION

Females reach sexual maturity when 21 to 25 years old. They are ovoviviparous, with a litter size from ( 1 to 30 ) varies regionally and larger females have more and larger pups. Gestation period varies regionally, from 18 to 24 months, to only 12 months in the Black Sea ( where largest females pups and litters occur ).This species is thought to have the longest gestation period of the elasmobranches. The young are born head-first with cartilaginous sheaths on the spines to protect the mother from injury.

 

  • SWIMMING

Slow swimmers but undertakes long distances.

 

  • SHARK ATTACKS

Harmless, not dangerous to man except through lacerations from the mildly toxic dorsal spines.

 

  • POPULATION REPORT

Common, but stocks are nearly depleted in many areas. Near threatened globally ( endangered northeast Atlantic, Vulnerable northwest Atlantic ). Extremely well-studied. Possibly once the most abundant shark and the most important commercial species, utilised for meat ( high value in Europe ), liver oil and fins and supporting large target trawl and line fisheries comparable to those for bony fishes. Its slow growth, late maturity, longevity and low reproductive capacity make it highly vulnerable to overfishing, particularly since aggregations of large pregnant females are usually targeted. Few fisheries are managed, some stocks are now very seriously depleted or collapsed and catches declining steeply. Also of commercial fisheries significance because large numbers may damage fishing gear and affect catches of other species. Targeted by sports anglers in some regions, displayed in public aquaria, and important for scientific research and teaching.
 
     

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