Bottom trawling is a fishing practice that herds and captures the ‘target species’, like ground fish or crabs, by towing a net along the ocean floor.
Fishers use trawls to catch species that live on or close to the seafloor such as cod, hake, shrimp, octopus, mullet, halibut or anglerfish. It also captures a lot of ‘by-catch’, unwanted or non-target fish that are not intended to be caught.
Trawling destroys the natural seafloor habitat by essentially rototilling the seabed. All of the bottom-dwelling plants and animals are affected, if not outright destroyed, by tearing up root systems or animal burrows. Suspending bottom sediment changes the entire chemistry of the water, including nutrient levels.
Bottom trawling is legal in some areas of Australian waters, but it is prohibited or restricted in others, according to Queensland Business and AFMA. Regulations and enforcement vary, and environmental protection measures are not always effective, leading to potential impacts even within Marine Protected Areas according to ResearchGate.
Sources: https://www.usgs.gov/programs/cmhrp/news/what-drag-global-impact-bottom-trawling ; Greenpeace
