Bottom trawling is a fishing practice that aims to catch a large number of specimens of target species by towing a net along the ocean floor.
This method uses heavily weighted nets and when these nets are dragged along the seafloor, everything in their path is disturbed or destroyed. When a trawler runs over corals to catch fish, they’re destroyed and they can take centuries to re-form, and so is the whole community that had formed around them.
Moreover, this is one of the most indiscriminate kinds of fishing because the small mesh, designed to confine fish inside, allows few other animals to escape.
The problem is that many marine animals, like sea turtles or marine mammals, which rest and forage on the bottom, are at risk of being captured bycatch. A device called “Turtle Excluder Device” has greatly reduced these risks in some trawl fisheries and might even allow small cetaceans to escape as well.
Finally, this method also has negative impacts on the climate. In fact, when nets rake the seabed, they lift up land that stores CO2, thus allowing its release back into the environment.