SHARK GALLERY

Piked dogfish (Squalus acanthias)

Piked dogfish - Squalus acanthias

© Ian K Fergusson

(Smith & Radcliffe, 1912).
Fr Aiguillat commun
Sp Mielga; Agullat (Catalunya); Quissona (Balearics); Aullat (Valencia)
It Spinarolo; Ugghiata (Palermo); Arculate (Rimini); Spinoelo (Liguria); Ferraro (Naples); Asią (Venice)
Ma Mazzola griza; Mazzola bix-xewka

Diagnosis

A moderately large, slender and very abundant dogfish with two spined dorsal fins, no anal fin and narrow rounded snout. Spine of first dorsal fin shorter than that of second; origin of first spine behind the pectoral free tips. Caudal fin without subterminal notch; keels present on lower caudal peduncle. Well-developed precaudal pit on dorsum. Upper and lower leeth rather similar and with oblique cusps. Colour  light or mid-grey above, lighter ventrally, with conspicuous white spots on the body and no white tips or edges on the dorsal fins.

Size

To about 150cm TL but generally much smaller, typically 120cm or less; size at birth 22 to 33cm.

Status and Distribution

N.E. Atlantic: Common or abundant; cosmopolitan but antetropical. Almost entire region over continental shelves, from the boreal Arctic (Iceland and Barents Sea) southwards along all European shores including the Baltic; Iberia south to African coast, with southerly limits at Western Sahara; also insular at the Canaries and Madeira.
Mediterranean Sea Common or abundant; cosmopolitan. Entire Mediterranean region; Sea of Marmara and Black Sea.

Biology

An abundant and well-studied shark occurring both coastally and offshore, also in estuaries and brackish zones but not penetrating freshwater. Piked dogfish frequent waters from the intertidal zone down to at least 950m, though generally shallower near the bottom over sand, mud or fine gravel substrates and especially in the vicinity of submerged banks.  These sharks favour colder water temperatures of between 7 to 15C and will migrate both vertically and horizontally to remain within such an optimum range. Longer distance seasonal migration is well-known in this species, both in European seas and elsewhere. Often forming very large schools, the piked dogfish, albeit  a somewhat slow swimmer, is nevertheless an active predator of a wide variety of teleosts, including clupeids such as sardines and herrings, blennies, gadoids and flatfishes; also cephalopods such as cuttlefish and squid, octopi, shrimps, crabs, euphasiids, polychaetes and other benthic invertebrates. It will also scavenge from bottom-set longlines, fish-traps and nets.  These sharks are themselves prey to a number of larger sharks, both demersal and pelagic. Underwater remote video cameras fitted to bottom-trawls have documented these sharks swimming at considerable burst-speed in erratic vectors across the substrate in an effort to evade capture; usually they are more sluggish. The stock-structure of Northeastern Atlantic piked dogfish has been a frequent source of investigation, not least given the commercial importance of these sharks in a number of European fisheries. The interelationship of the stocks remains uncertain and migratory patterns may have shifted considerably over time, explaining in part the often-varying results from tagging research conducted since the early 1960's. There was sufficient evidence to once demonstrate the existence of essentially two major stocks off the British Isles a northerly stock, that migrated between the Irish Sea and Norway, and a southern stock that frequented the English Channel and environs. Today the situation is less readily discernable. These sharks also shoal spatially and temporally by sex, which may again effect the outcome of tagging studies where returns are gathered by commercial fishing. An ovoviviparous species, with 2 to 11 young which are born at a sex ratio of 11. Gestation period is 18-22 months, with females giving birth once every two years. Females mature after ca. 10 years at 70 to 100cm TL; males after ca. 11 years at 60 to 72cm.

The Shark Trust, 36 Kingfisher Court, Hambridge Road, Newbury, Berkshire, RG14 5SJ, UK.
Tel(+44) 01635 551150, Fax(+44) 01635 550230



  *     *  


[Sharks] [Sharks & Shark Attacks] [Mediterranean Shark Species] [Great White Shark]
[Free Webpage Review] [Sales Page] [Movies Page] [YugoMuseum] [Web Design]

Stock trading Tips and Tactics | Trading Gaps | Elliot Wave Trading | Trading Ideas