Scientific name...............Squalus Acanthias
Other common names..........Piked dogfish, Whitespotted spurdog
The Spiny dogfish is also known as the piked dogfish or whitespotted
spurdog. It is identified by a large spiracle behind each large eye,
the presence of spines on the two dorsal fins, and the lack of an
anal fin. This shark is a slender dogfish, narrow head, relatively
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. The
spines of the spiny dogfish are formed from material much like that
of our teeth. Growth zones marked on the spines enable us to
determine the age of the shark. Some have been found that are 25
to30 years old.
The maximum length these sharks can grow is 4 feet, highly variable
regionally. Males mature at ( 24.5 to 39.3 inches ) and females
mature at ( 25.9 to 47.2 inches ). Pups are born at ( 7.3 to 12.9
The smooth edged short and oblique teeth are similar in both the
upper and lower jaws.
Spiny dogfish sharks are gray to bluish-gray to a brownish color on
above, and lighter to white below, often with white spots on the
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.
Their diet includes small fishes, such as cod, herring, menhaden,
and haddock, as well as invertebrates such as krill, squid,
scallops, and crustaceans. Can capture and dismember prey larger
than itself. The spiny dogfish uses its spines defensively when it
curls itself around in a bow to strike an enemy. It is very probable
that the spines are slightly poisonous.
Mainly demersal, apparently also epipelagic, sometimes solitary or
schooling with other small sharks, often forming immense dense
feeding aggregations 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 adults schools occasionally reported. They are
slow swimmers but undertakes long-distant seasonal migrations
north-south or deep-shallow as water temperature changes, prefers
45-59 F ( 7-15C ).
They are found almost world-wide, except tropics northern and
southern hemisphere populations and limited genetic mixing between
some stocks with overlapping range and feeding grounds but different
migration patterns. Spiny dogfish are cold-water sharks, preferring
temperatures from ( 45-59F ). They are caught in waters down to
about 2,600 feet deep, but not exclusively in deep water. They form
extremely large schools, routinely frequenting the shallow and
coastal waters of higher latitudes in spring and fall, and migrating
into deep waters during cooler winter months. Often on soft
sediments in enclosed and open bays and estuaries, where most
nursery grounds occur.
These sharks are ovoviviparous, with a litter size of ( 1 to 32 ),
although 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
Not dangerous to man except through lacerations from the mildly
toxic dorsal spines.
Common, but stocks are nearly depleted in many areas. ( Endangered
northeast Atlantic, Vulnerable northwest Atlantic ). Extremely well
studied. Possibly once the most abundant shark and the most
important commercial species, utilized 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.