ScubaBrucie

Bottom trawling is a fishing practice where a net is dragged along the bottom of the sea to catch the seafood that lives there. This is often done with 2 horizontal steel beams, each up to 12 metres long, which indescriminately catch or destroy most life in their path. This practice is exactly the same as dynamite fishing a coral reef or burning the rainforest in that the habitat is destroyed in return for an immediate, comparatively small, cash crop.

On November 18 2004 the United Nations General Assembly urged nations to consider temporary bans on high seas bottom trawling. The UN Secretary Generall reported that 95 percent of damage to seamount ecosystems worldwide is caused by bottom trawling. After a beam trawler has been through the seabed looks like a highway with most life destroyed. This life includes the seafood catch and everything else as well. This so called “bycatch” is a huge waste of everything in the ecosystem and includes the corals which are home to a diverse community of marine organisms.

Bottom trawling is bad enough in shallow seas but now we have a major ecological disaster. Deep water trawlers have come to account for about 80% of the bottom fishing catch from the high seas. The massive nets that drag the bottom and weigh up to 15 tons destroy deep-sea corals and sponge beds that have taken centuries or millennia to grow. The trawlers target fish such orange roughy and grenadiers for food, and sharks for fin soup and the cosmetic industry. These fish are generally long-lived, slow growing and late maturing so their populations take decades, even centuries to recover.

And because most deep-sea fishing occurs on the high seas in international waters, far from the watchful eyes of regulatory agencies, its impacts on species and ecosystems is generally neither monitored nor controlled. We know that it is an ecological disaster but we have no idea of the scale of that disaster.
 

Here is a Greenpeace article: http://www.greenpeace.org.uk/oceans/supermarkets/beamtrawling.cfm