The problem of illegal, unreported, and unregulated fishing is well recognized, yet conventional monitoring, control, and surveillance mechanisms administered by coastal and flag states have so far achieved limited success. The EU IUU Regulation is one of the most recent instances of trade and marketplace measures being implemented at the domestic rule level to block out IUU-caught fish. It aims at preventing any harvesting, processing, and re-exporting states from the circumvention of internationally agreed fisheries management goals. The immediate question for international law is whether unilaterally created trade-restrictive measures would affect the development of a truly global strategy to combat IUU fishing as a global activity. This article responds to the inquiry by exploring the potential and legitimacy limitations for domestic trade regulation to be effective and fairly nondiscriminatory. It draws on the regime theory to provide further insights into the ways of reconciling and synergizing disparate fisheries and trade management systems.