Illustration: Jón Baldur Hlíðberg
Ocean quahog fishing grounds in 1998-2011 (t/nm2), all gear combines. dark areas indicate highest catches.
Source: The Marine Research Institute
Ocean quahog catch (t) in Icelandic waters
Source: Statistics Iceland
Ocean quahog catch (t) by month
Source: Statistics Iceland, weight reports
Value of exported ocean quahog products by main countries in 2008 (FOB million ISK)
Source: Statistics Iceland
Scientific: Arctica islandica. English: Ocean quahog, Icelandic cyprine, black clam, black quahog. Icelandic: Kúfiskur, kúskel. For more languages see the Marine Animal Dictionary.
Biology and distribution
The ocean quahog is large bivalve that can reach a height of up to 10 cm. It grows rather rapidly during the first years, but the growth slows down after it reaches sexual maturity at the age of about 20 years, at the size of 6 to 7 cm. The ocean quahog can live to a very old age; the oldest individual measured in Icelandic waters was estimated to be about 400 years old. This makes the ocean quahog the longest lived animal on earth. The ocean quahog lives buried in the sediment so only a small opening of the shell is visible. It feeds by filtering phytoplankton and organic material from the sea,
The ocean quahog is found all around Iceland on sand or mud bottom at depths of 5 to 50 m. It also occurs deeper. Where conditions are favourable, the density can reach up to 88 shells per m2, or 8 kg. The total stock size estimated in Icelandic waters is more than 1 million tonnes. The ocean quahog has a wide global distribution. It is found in European waters from the White Sea in the north to the Strait of Gibraltar in the south. It is also around the Faroe Islands, and from Labrador to Virginia in North America.
Catch and fishing methods
The fishery for ocean quahog is very specialized and have fluctuated greatly in the past. Due to marketing reasons the fisheries have been negligible for the last years. Historically the ocean quahog has also been fished with smaller dredges for bait in the cod fisheries.
See the Marine Research institute
Processing and markets
The ocean quahog catch is frozen and exported to USA where it is mostly processed into clam chowder soup. A small local market also exists for ocean quahog as bait.
References and further information
- Gunnarsson, K., Jónsson, G., & Pálsson, Ó. K. (1998). Sjávarnytjar við Ísland (Marine resources in Icelandic waters). Reykjavík: Mál og Menning, 280 pp. (in Icelandic)
Ragnarsson, S. A., & Þórarinsdóttir, G. G. (2002). Abundance of ocean quahog, Arctica islandica, assessed by underwater photography and a hydraulic dredge. Journal of Shellfish Research 21 (2), 673-676.
Schone, B. R., Fiebig, J., Pfeiffer, M., Gle, R., Hickson, J., Johnson, A. L. A., et al. (2005). Climate records from a bivalved Methuselah (Arctica islandica, Mollusca; Iceland). Palaeogeography 130 (1).
Þórarinsdóttir, G.G. and Einarsson S.Tr. 1995. Kúfskel. Lífríki sjávar. Násmgagnastofnun/Hafrannsóknastofnunin. 5 p.
Þórarinsdóttir, G. G., & Jacobson, L. D. (2005). Fishery biology and biological reference points for management of ocean quahogs (Arctica islandica) off Iceland. Fisheries Research 75 (1), 97-106.
Hreiðar Þór Valtýsson, University of Akureyri