At various times, the sustainable use of living marine resources in the high seas outside exclusive economic zones, as well as in areas under the jurisdiction of Arctic coastal states, has been severely damaged by illegal, unregulated and unreported fishing. As the climate warms, the threat of unregulated fishing has also emerged on the high seas in the central Arctic Ocean. The Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean was signed in Ilullissat (Greenland, Denmark) on October 3, 2018 following multi-round negotiations in the so-called “five plus five” format – representatives of five Arctic states plus representatives of four non-Arctic states and the European Union. This new international legal document reflects national interests in the optimal use of living marine resources of the Arctic states, the Arctic indigenous peoples and residents, as well as interested states.The present article shows the evolution of international legal instruments to prevent illegal, unregulated and unreported fishing in the high seas. Particular attention is paid to the study of normative and doctrinal materials revealing the treaty practice of states in the Arctic enclaves. A legal interpretation of the provisions of the 2018 Agreement is also given. In the study, the authors used historical, comparative-legal and other general scientific and special legal methods.From an international perspective, the 2018 Agreement is an innovative legal document that reflects the interests of Arctic and non-Arctic states alike. Despite concerns about the participation of the latter (China, in particular) on the part of Western countries, the Agreement was nevertheless signed and ratified before possible commercial fishing on the high seas in the Central Arctic Ocean starts. This would prevent illegal, unregulated and unreported fishing in advance and thus prevent the depletion of living marine resources in this part of the Arctic Ocean, unlike what happened in other enclaves of the high seas in the Northern Hemisphere.The entry into force of the 2018 Agreement marked the beginning of cooperation among interested states in the prevention of unregulated high seas fishing in the Central Arctic Ocean. In addition to the general purpose of the Agreement, scientific cooperation between the Parties will contribute to a better understanding of the leastexplored area of the high seas. It is likely that environmental cooperation in the Central Arctic Ocean will expand considerably in the future.