Scraping the bottom
This is how shrimps (prawns) are caught off La Paz in the Sea of Cortez, Mexico. Whether a trawl net is small, like this one, or large, the design is similar worldwide: two steel doors help keep open the maw of the net as a boat drags it along. Such a design is hugely effective, catching shrimps but also everything else in its path. As it drags along the bottom, it also destroys whole communities, including the corals and sponges that provide habitat for so many other animals and which may take years to grow back.
Nikon D2X + 16mm lens; 1/125 sec at f9; ISO 100; Subal housing; Sea & Sea YS90 strobes.