Slipping the net: why is it so difficult to crack down on IUU fishing?

Illegal, unreported and unregulated (IUU) fishing is now well recognized as a key threat to the management and sustainability of fisheries and therefore a pressing matter of global concern. Due to the illicit, shadowy nature of such activities, estimating the precise scale of IUU fishing is inherently difficult. Despite uncertainities it is clear that the scale of this activity is enormous with estimeates of the total annual catch for 2011, for example, rranging from 11 to 26 million tonnes, equating to 14-33% of the world's total legal catch.