'By tackling illegal fishing, it would also help conservation in the ocean, which has long been a desire of the American people.'The UNODC report also noted that vessels engaged in criminal activities are more likely to be involved in illegal, unreported and unregulated (IUU) fishing. IUU vessels are thought to account for about one fifth of the global fish catch, and by definition operate outside of all regulations, making sustainable management impossible in areas where they are rife. Vessels engaged in crime are known to change their name and flag States (where they are legally based) regularly to avoid detection. Carrying a unique and unchangeable IMO number makes this impossible. 'Governments are well aware of the security issue, and many of them are taking steps to combat it in their own waters,' said Mr Manuel. 'But when we get to the high seas, it's a different matter; there's been very little progress, despite clear evidence of criminal activity including piracy, drug smuggling and illegal fishing. 'When merchant ships have to be identifiable and trackable, there's no reason we can see why other types of vessel should get a free ride.' Mandatory vessel ID and tracking would also benefit human rights and sustainable fishing, observed David Miliband. 'It seems pretty obvious that if authorities know who owns a vessel, where it is and where it's sailing to, then the owners of the vessel are much more likely to stay within the law,' he said. 'Mandatory vessel ID and tracking would reward those who play by the rules and penalise those who don't - it would create economic opportunities for the "good guys", and improve the social conditions of seafarers.' In 2011, a UN Office on Drugs and Crime (UNODC) report on illegal fishing documented cases where …'fishers are held as de facto prisoners of the sea… a particularly disturbing facet of this form of exploitation is the frequency of child trafficking in the fishing industry'. The IMO is currently debating whether to remove the exemption given to fishing vessels from the regulations concerning identification numbers. But even if the exemption is removed, vessels would be encouraged, not mandated, to carry them.