Download 41 Spiny Dogfish Order: Squaliformes Family: Squalidae Genus

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Spiny Dogfish
Order: Squaliformes
Family: Squalidae
Genus: Squalus
Species: acanthias
Key Morphological Characteristics:
• The Spiny dogfish has a long, lithe body with large eyes and a flatter head. The first
dorsal fin is located in the middle of the pectoral and pelvic fins and the second is a third
smaller than the first. The dorsals have poisonous spines on the front of them and the
pectoral fins are extremely rectangular. There is no anal fin and the caudal fin is very
flexible, with a large upper lobe and very small lower lobe.
• The dorsal side is usually gray with some brown tint, and there are rows of white spots
along the sides above the pectoral and pelvic fins. These spots fade with growth and may
disappear completely. The underside can range from light gray to bright white. (Bester)
Geographical Distribution:
• S. acanthias can be found globally in cooler waters. Atlantic populations exist from
Iceland to Russia and down to South Africa with the Mediterranean and Black Sea in
between, as well as from Argentina to Greenland. In the Pacific they appear from New
Zealand to the Bering Sea to Chile. (Bester) (Froese and Pauly)
Habitat:
• Spiny dogfish usually stay near the bottom but often travel to the surface of both coastal
and pelagic regions. They prefer seawater over continental shelves within depths of 900
meters.
• They often stay in schools while growing and are segregated by size, but not necessarily
by sex. Juveniles usually stay in open water while sexually mature females remain close
to shore.
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This species is very migratory and regularly can be found off of Cape Cod in summer,
then Long Island in the fall and North Carolina in winter. In spring they turn back north
and reach Maine and Canada by June and July. (Bester)
Size, Age, and Growth:
• Male dogfish reach an average length of 60-90 cm and max out at 100 cm, while females
average 76-107 cm and a maximum of 124 cm.
• The age of maturity for males is 6 years and 60 cm in length, while females become
sexually mature after 12 years and grow to 76-78 cm.
• Spiny dogfish live for 25-30 years. (Bester)
Food Habits:
• Spiny dogfish feed primarily on school pelagic bony fish such as capelin, herring,
mackerel, sand lance, and menhaden. Other prey items include jellyfish, wolffish, squid,
crabs, flatfishes, shrimp, sea cucumbers, and octopi.
• Fishermen despise this species because they will eat through mackerel and herring nets to
eat the captured fish or just release them.
• Some experts believe they do not eat very much during the winter migration because
populations often look scrawny at the beginning of spring. (Bester)
Reproduction:
• This is an ovoviviparous species that may have the longest gestation period of any
vertebrate at around 24 months. At birth, 1-15 pups are born headfirst at lengths within
20-33 cm. (Bester)
Predators:
• Spiny dogfish are prey in some way to red hake, cod, goosefish, larger Spiny dogfish, as
well as possibly seals, orcas, and larger sharks. (Bester)
Importance to Humans:
• This species is heavily fished to be used in the popular British dish “fish and chips,” as
fishmeal, and for their liver oil. They are caught commercially with sink gill nets and
otter trawls. They can also severely damage nets when tangled. (Bester)
Danger to Humans:
• This species is harmless except for the spines along the dorsal fins, which can be very
painful if the fish is not handled carefully. The spines are actively used for defense by
curling the body to expose the spines and attacking with those. (Bester)
Conservation:
• The IUCN considers the Spiny dogfish to be “Vulnerable” because it is fished so heavily
and restrictive measures were necessary to sustain the population without collapse. Since
fishermen used to target mature females for their size and their reproductive rate is very
low, there has been a great decrease in the number of pups and the species is actually in
danger of collapse without management. Measures were taken at the new millennium to
regulate fishing of this species and prevent collapse. (Bester)
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Spiny Dogfish:
Bester, C. “Spiny Dogfish.” Ichthyology. Florida Museum of Natural History. 21
Nov 2009. http://www.flmnh.ufl.edu/fish/Gallery/Descript/SpinyDogfish/SpinyDogfish.html
Froese, R., and Pauly, D. 2009. FishBase. World Wide Web electronic publication.
http://fishbase.org/Summary/speciesSummary.php?ID=731&genusname=Squalus&speciesname
=acanthias&lang=English, version (11/2009)