Demersal Trawl - Sole Trawl
This is a trawl towed on the seabed, with the mouth held open by a pair of otter boards (trawl doors) designed and rigged to target Dover sole. Generally these nets are fairly small and low with the trawl doors very close to the wing ends of the trawl.
Sole trawls are often worked on mobile sea beds of sand and mud, often in fairly shallow water. The net is designed to be very low and just catch the fish that are really close to the seabed. Some of the inshore boats in SW England have rigged their sole trawls to be no more than 300mm off the seabed thereby minimising round fish by-catch. By catch and undersized fish capture can be managed using changes in codend mesh size and by using some of the more common selective devices.
These trawls are towed without any sweeps and bridles, this minimises seabed contact to the net and the trawl doors. The nets have very lightweight ground gear on them and they are designed to ‘skim’ over the soft muddy seabed . Too much contact and the gear will come fast on the mud and stop the vessel. The trawldoors used are of lightweight construction due to the shallow water the gear is towed in. The traditional flat wooden doors that used to be used in this fishery were one of the few trawl doors that depended on seabed contact to help them spread. Nowadays most vessels are using more modern foil type doors with wider keels that help reduce any seabed penetration of the trawl doors.
Sole trawls are designed to target Dover sole. These are fairly small nets featuring very short wings, a wide mouth and a low headline. The headline is usually no more than 750mm off the seabed, many will be as low as 300mm high to help minimise round fish by-catch. These nets are towed directly behind the trawl doors, without any sweeps and bridles. Dover sole tend to be very tight on the seabed almost burying themselves in the seabed silt, will not be herded by the sweeps. They are often used in twin or triple rig configurations particularly on inshore grounds