MARINE salvage companies responded to more than 120 shipping casualties around the world last year, involving nearly 1.4 million tonnes of oil and hazardous chemical pollutants. These are the findings of the International Salvage Union's (ISU) first annual pollution prevention survey. ISU president Okkie Grapow said: 'Last year, our members recovered 1.25 million tonnes of oil from 14 tankers where there was a threat to the marine environment following fires, collisions, groundings and structural failures.' The amount of oil was the equivalent of more than 33 spills of Exxon Valdez size, he said. 'The results of this survey make the point that salvage is the most effective means of pollution prevention, as it keeps the pollutant in the ship. He said governments must continue to invest in spill clean-up resources but salvage intervention - to prevent the release of oil and chemicals in accidents - was the most cost-efficient way of protecting the marine environment. The ISU has a membership of 43 marine salvors in 32 countries. Last year, they performed 126 operations that involved the prevention or mitigation of significant pollution. The largest recovery of crude oil from a shipping casualty concerned the tanker Tochal. The salvage team recovered the entire 275,000-tonne cargo of Iranian light crude by means of a ship-to-ship transfer. The Tochal suffered severe bow damage in heavy weather off South Africa in May. Last year, ISU member companies performed a total of 24 ship-to-ship transfer operations involving oil cargoes and ships' bunkers. The smallest involved the removal of 12 tonnes of bunkers. In addition, there were three cargo transfers from vessels carrying hazardous substances. Member companies also successfully salved 11 casualties involving hazardous chemicals.