BottomSchleppnetze

BottomSchleppnetze, or bottom trawl nets, are fishing gear designed to catch demersal species living on or near the seabed. They consist of a large, cone-shaped net towed along the bottom by a fishing vessel. The mouth of the net is kept open by two otter boards (doors), while ground gear such as chains or rollers helps the net maintain contact with the seabed. The cod end holds the catch, and the net may include selective features or different mesh sizes to influence selectivity.

Design and operation vary, but most bottom Schleppnetze are deployed from stern trawlers and towed at speeds suitable for sweeping the seabed. The ground gear is important for keeping the net on the bottom and for controlling the way it interacts with the substrate. Some configurations incorporate bycatch reduction devices or alternative mesh arrangements to target certain species or sizes.

Target species in many regions include cod, haddock, and flatfish such as plaice and sole, as well as various demersal shrimp and other invertebrates. Bottom trawling is effective for capturing these species but can disturb the seabed and result in bycatch of non-target organisms, including juveniles.

Environmental impact and regulation are central to the use of BottomSchleppnetze. The gear can cause habitat disturbance and seabed damage, leading to habitat loss in sensitive areas. Fisheries management employs measures such as mesh-size regulations, quotas, seasonal closures, and area restrictions, along with gear modifications to reduce bycatch and environmental impact. Ongoing research seeks to improve selectivity and minimize damage while maintaining catch efficiency.