Bottomtowed

Bottomtowed refers to gear and towing practices in which equipment is maintained in contact with the seabed during operation. The term is used in commercial demersal fisheries, benthic sampling, and seabed mapping, spanning depths from shallow coastal zones to continental shelves and beyond.

In fishing, bottomtowed gear includes bottom trawls, beam trawls, and dredges. These tows are conducted at speeds typically around 2 to 4 knots and for periods ranging from roughly 20 to 60 minutes, with gear designed to spread and ride along the seabed. The arrangement uses heavy doors or ground gear to keep the net or device close to the bottom, enabling capture of species that dwell on or near the substrate and allowing effective scraping or sampling of the seabed substrate.

In scientific and survey applications, bottomtowed devices encompass grab samplers, corers, sediment profilers, and camera sledges. These instruments are towed along the seafloor to collect physical samples, deploy sensors, or acquire imagery of habitat structure and sediment characteristics.

Environmental and governance considerations accompany bottomtowed activities. The disturbance of sediments, potential damage to benthic habitats, and impacts on seabed communities are well documented concerns. Mitigation measures include gear modifications to reduce contact, shorter tow durations, depth- and area-based restrictions, and protected-area closures. International and regional frameworks, such as the FAO Code of Conduct for Responsible Fisheries and regional fisheries management organizations, provide guidelines and, in some cases, restrictions to promote sustainable use of bottomtowed resources.