To conclude on the total impact of trawling, an extensive mapping of fishing effort and bottom habitat would be necessary. In general, the response of benthic organisms to disturbance differs with substrate, depth, gear, and type of organism. Seabed characteristics of the Barents Sea are scarcely known and the lack of high-resolution maps of benthic habitats and biota is currently the most serious impediment to effective protection of vulnerable habitats from fishing activities.
An assessment of fishing intensity on fine spatial scale is critically important in evaluating the overall impact of fishing gear on different habitats and may be achieved, for example, by satellite tracking of fishing vessels. The challenge for management is to determine levels of fishing that are sustainable and not degradable for benthic habitats in the long run.
The quantitative effects of trawling have been studied to some degree. The most serious effects of otter trawling have been demonstrated for hard-bottom habitats dominated by large sessile fauna, where erected organisms such as sponges, anthozoans and corals have been shown to decrease considerably in abundance in the pass of the ground gear. Barents Sea hard bottom substrata, with associated attached large epifauna should therefore in particular be identified, but also the large soft sea bottoms covered by motile long lived epibenthos.
