Spurdog shark


Spurdog ©Peter Verhoog

Spurdog shark

Scientific name: Squalus acanthias
This slender shark gets its name from the spines in front of its dorsal fin. It can use these spines to defend itself by curling in a bow and striking at a predator.

Species information


Length: Up to 1.6 m
Weight: Up to 9.1 kg
Average Lifespan: Can live for up to 75 years

Conservation status

The spurdog is listed as Vulnerable by the IUCN Red List and is a Priority Species under the UK Post-2010 Biodiversity Framework.

When to see

Present all year round


Also known as the spiny dogfish, the spurdog is a predator that feeds on bony fish, and sometimes even smaller sharks! It is a migratory species that spends the winter months in deep water, and the summer months in warm coastal waters.

They often travel in groups which makes them an easier target for fisheries. It's difficult for these sharks to recover from overfishing, because they are very slow to reproduce, typically having 1 litter of pups every 2 years.

How to identify

The Spurdog shark has a pointed snout, large eyes, and spines in front of its dorsal fins. Its streamlined body is a grey/brown colour on top with a lighter belly and rows of white spots down its sides.

In our area

Because the waters around NI are generally between 7 and 15 degrees Celcius, Spurdog are present throughout much of the year. They are most commonly found around Ballycastle and Red Bay, and pregnant females have also been seen along the Antrim coast between November and January. This suggests a pupping ground in the area. Critical areas such as pupping grounds need to be protected because this is an area that sharks live in when they are most vulnerable. As Spurdog sharks are categorised as Endangered in our local waters and are on the NI Priorty Species list we hope to be able to provide evidence through our tagging programme that will ensure spatial protection measures for them.


Found in the Irish Sea and Northeast Atlantic, and in temperate waters world-wide.

Did you know?

Female spurdog sharks have one of the longest pregnancies of any vertebrate, lasting between 18-22 months.

How people can help

The Wildlife Trusts are working with sea users, scientists, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or checking out our Action Pages.