Rational, sustainable use of marine living resources is a pledge of the normal reproduction of these resources and guarantee of their conservation for the benefit of the present and future generations. Realizing this fact, states and international organizations, for several decades, have dealt with the problem of maintaining rational fishery and working out of the system of measures directed on conservation of marine living resources, their reproduction and maintenance at the level of the maximum sustainable yield. In this respect, the largest international intergovernmental organization is the UN Food and Agricultural Organization (FAO), within which framework, during 10 years, the question of illegal, unreported and unregulated fishing (IUU fishing), causing damage to the world fishery, and endangering the preservation of the marine environment, threatening the stability of fishery, was discussed. The discussion of this problematic within the FAO framework has resulted in the adoption in November, 2009 of the Agreement on port state measures to prevent, deter and eliminate illegal, unreported and unregulated fishing.