One of the most contentious issues in management of marine fisheries is the use of mobile bottom contact gears, trawls and dredges. About 25% of world fish catch comes from the use of these gears and catch from trawls is an important element in food security in much of the world. At present, a continental shelf area approximately equivalent to 3 times the area of Brazil is affected by mobile bottom contact gear. Trawls can dramatically transform sensitive benthic ecosystems, eliminating much of the associated emergent surface dwelling flora and fauna especially on hard bottoms. Conversely, extensive studies have shown that there are fewer changes to less sensitive habitats, particularly in regions subject to frequent natural disturbance.