Dredges
Dregdes
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Ocean quahog or shellfish dredge Photo: Tryggvi Sveinsson |
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Catches (t) in dredges and whelk trap by species Source: Statistics Iceland, weight reports
Ocean quahog dredge catch (t) by months Source: Statistics Iceland, weight reports |
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There are basically four versions of dredges used in Icelandic waters: ocean quahog (often just referred to as shellfish dredge), scallop, sea urchin and kelp dredge. However, there is wide variation in the design of the dredge within each of these categories. Scallop fisheries were the most important of these and were also the first commercial dredge fishery to start up. Breiðafjörður Bay in western Iceland was the most important fishing area for scallop and kelp, while ocean quahog and sea urchin are harvested in shallow waters all around Iceland. Although commercial dredging only began in 1969, dredges had been in use in Iceland from the turn of the 20th century. These were used to catch ocean quahog for bait.
A typical dredge incorporates a heavy duty net bag attached to a rigid metal frame. The lower part of the dredge is often protected by chain mail or a leather or rubber mat. On traditional ocean quahog dredges, tooth bars are often on the lower part of the frame so that the dredge digs into the sediment for the bivalves (seashells). Currently commercial fisheries of ocean quahog in Icelandic waters are only conducted by one boat, specially designed to use hydraulic dredge. The teeth are replaced with water pumps that use jets of water to clean the sediments away from the quahog which is then scooped up by the dredge. Scallop and sea urchin dredges lack teeth as these animals do not dig themselves into the bottom. These two dredges are otherwise quite similar, except that sea urchin dredges are considerably smaller. Kelp dredges are quite different, they are more like claws that are dredged over the bottom.
Dredge tows are always much shorter than trawl tows as they only fish where the target species is in abundance on the bottom. Hydraulic dredges for ocean quahog are for example only towed for 3-10 minutes, nevertheless the catch can be up to 3 tonnes per tow.
References and further information
References: (Gunnarsson et al. 1998), (Kristjánsson 1985)
For full citation and further information on fishing gear see this page.
Hörður Sævaldsson / Hreiðar Þór Valtýsson University of Akureyri
