Ballast water provides stability and manoeuvrability to a light ship – it would be an uncomfortable and hazardous voyage without it swilling around down in the ballast water tanks – and it's free, courtesy of Neptune.The trouble is that as cargo goes out, ballast water comes in, usually from coastal or estuary waters teeming with organisms ranging from viruses to crustaceans, even fish and eels bearing no goodwill to the indigenous population and eco-system they end up in. It has been estimated by IMO that international merchant shipping carries the 'gee-whizz' figure of between three and twelve billion tons of ballast water around the world each year, with invasive species causing estimated losses of $138 billion annually to the economy of the U.S.A. alone.The IMO International Convention for the Control and Management of Ship's Ballast Water and Sediments 2004, now within single digits of ratification by the necessary thirty nations, attempts a remedy by making ship-owner... [More]