There has been increasing litigation in the WTO on environmental issues in recent years, much of it about fishing. Two cases, Chile–Swordfish and Faroes–Herring, brought to light the potential for conflict between trade and fisheries law through the imposition of port state measures by WTO members to prevent illegal, unreported, and unregulated (IUU) fishing, although both cases were settled before reaching Panel stage. Port state measures aim to combat IUU fishing by allowing countries to close their ports to IUU fish. This includes using trade measures and trade-related measures, such as import bans and transshipment bans, which may violate WTO law. The potential for conflict is even more acute now that the Port State Measures Agreement (PSMA) has come into force. This paper takes as its study Faroes–Herring, where the Faroes challenged certain EU regulations aimed at preventing IUU fishing through the use of port state measures. It examines whether these regulations comply with WTO law, and makes recommendations as to how a Panel or Appellate Body can resolve this type of dispute. Specifically, it focuses on ways in which international fisheries law can be incorporated in this process to avoid a conflict between international trade and fisheries law.