Throughout the world, overexploitation threatens the future viability of many fish stocks. This threat extends to the most remote areas on earth, including the Southern Ocean—that vast body of water surrounding the Antarctic continent. Indeed, the geographic isolation of the Antarctic is no longer an insurmountable barrier to the large-scale exploitation of fish stocks in that region. The Southern Ocean, however, is not without regulatory structure. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR, or The Convention, or Convention), a treaty that aims to achieve sustainable exploitation of marine stocks in the Antarctic, is the primary international instrument that applies to living resources in the Southern Ocean. The institutional bodies formed under CCAMLR act as a regional management regime that enacts conservation measures to ensure the sustainable use of Antarctic marine species. This management regime, however, faces its own difficulties. In particular, CCAMLR’s effectiveness is threatened by continued illegal, unreported and unregulated (IUU) fishing in the Southern Ocean region. The problem is particularly prevalent in the Antarctic, because a large part of the area constitutes high seas, thereby allowing states to fish freely under international law. Another factor contributing to the IUU problem is that CCAMLR conservation measures on the high seas do not apply to countries who are not parties to the treaty (non-party states). This article will outline the weaknesses in the CCAMLR regime and weaknesses in other international instruments in dealing with the IUU problem. It will also discuss applicable defenses that a state may raise in the event that it decides to take direct action against IUU fishing vessels in the high seas of the Southern Ocean, thereby exposing itself to potential liability under international law. One such defense is to claim a “state of necessity” that makes it imperative for a CCAMLR party state to take action in breach of international law. This paper will examine whether the dire threat to the Antarctic ecosystem posed by IUU fishing could sustain such a defense. Finally, this paper will consider the consequences of a defense of necessity and whether this would be an effective means to combat IUU fishing
