Fishing that takes place on flag-of-convenience vessels, outside the international regulatory structure, is increasingly undermining the ability of fishery conservation organizations to manage fish stocks. Among the most affected are high seas and highly migratory stocks such as tuna, swordfish, and toothfish. The traditional approach to addressing this problem, efforts to persuade non-member flag states to join international agreements, has met with little success. Recently, efforts by regional fishery management organizations to allow, or require, member states to refuse to allow the importation or transshipment of fish products that cannot be shown to be caught under the rules of the organization, have had much more of an effect in reinforcing conservation efforts. In response to these measures, some flag states have joined international agreements and some have taken steps to stop fishing activity by ships in their registries. Even ships that do not comply with these rules may cease to find markets for their products. The case of fishing regulations suggests both that, in an era of globalization, individual actors are willing and able to avoid international rules, and that collective international action to exclude them from the benefits of doing so can improve global regulatory efforts.