The impact of fishing in the deep sea goes far beyond just removing the fish. Fisheries are concentrated into places that have the greatest biological significance; places like seamounts and canyon walls where materials that are wafted in on currents support rich communities of species - corals, sponges, seafans and hydroids. Deep-sea fishing is said to be inflicting terrible collateral damage on these species as trawl meshes plough through the water. Off the east coast of North America bizarre and beautiful fields of glass sponges have been trawled to oblivion. In the Southern Ocean lush forests of invertebrates have been literally stripped from the top of seamounts by trawlers targeting orange roughy.
The move to deep-water fishing is being encouraged by governments who are offering subsidies to alleviate the hardship that has been brought on by the collapse of shallow-water fish stocks. Forty percent of the world's trawling grounds are now waters that are deeper than the edge of the continental shelves.