Trawling refers to the process of fishing that uses a fishing net through the sea water behind one or more boats. It is a common method of extraction of sea living resources.
It is the main cause of the degradation of the seabed which threatens the biodiversity. It kills a number of corals, sponges, fishes and the microflora on the seabed. Corals, particularly are damaged wouding the tissue and making them susceptible to infection. It also removes certain economically important sea weeds. The ocean sediments are disturbed causing the suspended solids to enter the seawater and causing turbidity affecting the penetration of sunlight. The suspended soilds can also cause growth of harmful algae causing algal blooms affecting the other biotic factors of the sea. The disturbance in the ocean sediments due to trawling causes the harmful pollutants like DDT that are trapped in the sediments reach the water column and enter the food chain of the living organisms.