Ocean quahog

Arctica islandica


Ocean quahog (Arctica islandica) © Paul Kay

The ocean quahog is a typical cockle-shaped bivalve, and the two halves of its hinged, rounded shell are thick, glossy and dark brown in colour.  It is a long-lived animal and is quite large for its kind, growing up to 13cm across.

Ocean quahogs can be found from just below the low water level to depths of about 500m.  They live buried in sand and muddy sand, often with their shells entirely hidden and just a small tube extending up to the surface of the seabed.  The tube is a siphon that keeps water flowing across the animal, so that it can breathe, capture food, and expel waste.

People do eat quahogs, although this is more common in North America, Iceland and Norway than in the UK.  Commercial fisheries for the bivalve suddenly increased enormously in the mid-1970s, and have remained at those levels ever since.

Ocean quahogs grow very slowly, and can take up to 50 years to reach market size.  They are at particular risk from bottom fishing gear, and, like other slow-growing animals, once their numbers have been reduced the populations can take a long time to recover.

Ocean quahogs are also an important food source for cod.


Other common names

Icelandic cyprine

Iceland cyprina


European distribution

Ocean quahogs are found all around British and Irish coasts and in offshore waters. The European range extends from Norway to the Bay of Biscay.


Conservation status/need

OSPAR list of threatened and/or declining species and habitats (Region II - Greater North Sea)


Further information

OSPAR List of Threatened and/or Declining Species and Habitats (Reference Number: 2008-6)

OSPAR Commission – Background Document for ocean quahog Arctica islandica

Food and Agriculture Organisation


Marine Life Information Network

World Register of Marine Species