bottom otter trawls (OTB)
OTB is the abbreviation for the fishing method bottom otter trawls. The funnel-shaped body of the net, which consists of different mesh sizes, is provided with a wing on each side at the front, which together with the upper and lower tension form a net opening reinforced by lines. The horizontal opening of the net is mainly achieved by two otter boards. The vertical opening is achieved by buoyancy bodies and weights on the bottom rope. The so-called ground tackle is adapted to the ground conditions. It usually consists of rubber discs, rollers or other spacers mounted on steel wire and is designed to maximise the catching capacity of the net and at the same time protect it from damage caused by uneven ground. Undesirable by-catches in this fishery are currently reduced by mesh sizes and mesh shapes and by sorting, selecting or guiding grids, especially at the end of the net (codend). So-called escape windows of square meshes in turn allow smaller fish to escape, while larger animals cannot pass through these windows.