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Effects of fishing activities on benthic ecosystems
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Effects of fishing activities on benthic ecosystems
Bottom trawling for fish and shrimp is one of the most common fishing methods in Arctic and Subarctic waters. The most widely used gear for bottom fishing in Icelandic waters is the otter trawl, which consists of a large net bag rigged with ground rope and a headline to keep the net open vertically. Otter boards are connected to the ground rope with heavy wire to keep the net spread horizontally and to hold the trawl down as it is towed along the seafloor. In general, the effects of otter trawling in shallow areas with a soft seabed are relatively minor for most of the smaller species. Effects of trawling on large structural biota such as corals and sponges are considered to be more severe. Although little evidence exists on the effects of trawling on this group of animals, it is likely that their distribution is now more fragmented than prior to fishing.

Effects of otter trawling have been investigated in Icelandic waters with a manipulative field experiment. The experimental design was rigorous, with four areas intensively trawled and four areas left undisturbed. The results showed that only a few species at this site were affected by trawling.

Dredges are also considered to have a large impact on benthic communities. The scallop dredge and the hydraulic dredge, the latter used in the ocean quahog (Arctica islandica) fishery, are used in Icelandic waters. The impact of hydraulic dredging on benthic fauna is currently being investigated.

The available data on fishing effort of the Icelandic fleet is very accurate and have made it possible to map in detail the distribution of otter trawl effort around Iceland. Over the next few years priority will be given to map the distribution of benthic assemblages and habitats which are considered to be sensitive to trawling disturbances. Such information will be important in order to predict which species and habitats are being at risk of being damaged by fishing activites and for protection of important marine habitats in the future.
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