ottertrawls

Ottertrawls are a type of fishing trawl net. They are characterized by otter boards, also known as doors, which are large, flat boards that are towed along the seabed or through the water column. These boards spread the mouth of the net open horizontally as the fishing vessel moves forward, allowing the net to cover a wider area and capture more fish. The otter boards are connected to the net by warps, which are heavy ropes or cables.

The size and shape of the otter boards are designed to generate hydrodynamic forces that push them outwards, thus keeping the net's opening wide. This design allows for efficient fishing of various species, depending on the mesh size and the depth at which the trawl is deployed. Otter trawls can be used for bottom trawling, where the net is dragged along the seafloor, or for midwater trawling, where it is towed at various depths within the water column.

Ottertrawling is a widely used commercial fishing method globally. While effective for catching large quantities of fish, concerns have been raised regarding its potential environmental impact, particularly regarding seabed habitat disturbance and bycatch of non-target species. Regulations and gear modifications are often implemented to mitigate these impacts. The technology has evolved over time to improve efficiency and reduce some of the associated environmental pressures.