A new paper in the latest Marine Policy journal by Pramod Ganapathiraju et all, tackles this ambitious task with an interesting methodology.
The paper concludes with some assertions I completely agree:
First, illegal fishing activities remain a major problem for the seafood industry and seafood consumers. Second, the lack of transparency in highly complex and diffuse wild seafood supply chains allows illegal and unreported catches to be easily laundered and mixed into legitimate supplies entering international trade. Third, very few tools currently exist to monitor and interdict illegal catches entering the United States through seafood imports.
Full paper here