Bottom trawling: Industrial trawlers once avoided coral reefs and other rocky regions of the ocean floor because their nets would snag and tear. But the introduction of rockhopper trawls in the 1980s changed this. These trawls are fitted with large rubber tires or rollers that allow the net to pass easily over any rough surface. The largest, with heavy rollers over 75cm in diameter, are very powerful, capable of moving boulders weighing 25 tonnes. Now, most of the ocean floor can be trawled down to a depth of 2,000m.

Cyanide fishing: In this technique, fishers squirt sodium cyanide into the water to stun fish without killing them, making them easy to catch. Cyanide fishing on coral reefs began in the 1960s to supply the international aquarium trade. But since the early 1980s, a much bigger, more profitable business has emerged: supplying live reef fish for the restaurants of Hong Kong, Singapore, and, increasingly, mainland China. Some 20,000 tonnes of live fish are eaten annually in the restaurants of Hong Kong - and for every live fish caught using cyanide, a square metre of their coral reef home is killed.

Dynamite fishing: In this technique, dynamite or other explosives are set off under water. The dead fish floating to the surface are then simply scooped up. The explosives completely destroy the underwater environment, leaving it as rubble. Dynamite fishing has contributed to massive destruction of, for example, Southeast Asian coral reefs over the past 20 years.

Ghost fishing: Ghost fishing occurs when fishing gear is lost or abandoned at sea. The gear can continue to catch fish, dolphins, whales, turtles, and other creatures as it drifts through the water and after it becomes snagged on the seabed. When driftnets were used on the High Seas, an estimated 1,000km of ghost nets were released each year into the North Pacific Ocean alone.