pulled. The numbers taken grew rapidly in the 1960s, peaking around 1968 with a global total of 1,250 bears that year. Contemporary regulations Concerns over the future survival of the species led to the development of national regulations on polar bear hunting, beginning in the mid-1950s. The Soviet Union banned all hunting in 1956. Canada began imposing hunting quotas in 1968. Norway passed a series of increasingly strict regulations from 1965 to 1973, and has completely banned hunting since then. The United States began regulating hunting in 1971 and adopted the Marine Mammal Protection Act in 1972. In 1973, the International Agreement on the Conservation of Polar Bears was signed by all five nations whose territory is inhabited by polar bears: Canada, Denmark, Norway, the Soviet Union, and the United States. Member countries agreed to place restrictions on recreational and commercial hunting, ban hunting from aircraft and icebreakers, and conduct further research. The treaty allows hunting "by local people using traditional methods". Norway is the only country of the five in which all harvest of polar bears is banned. The agreement was a rare case of international cooperation during the Cold War. Biologist Ian Stirling commented, "For many years, the conservation of polar bears was the only subject in the entire Arctic that nations from both sides of the Iron Curtain could agree upon sufficiently to sign an agreement. Such was the intensity of human fascination with this magnificent predator, the only marine bear." Agreements have been made between countries to co-manage their shared polar bear subpopulations. After several years of negotiations, Russia and the United States signed an agreement in October 2000 to jointly set quotas for indigenous subsistence hunting in Alaska and Chukotka. The treaty was ratified in October 2007. In September 2015, the polar bear range states agreed upon a "circumpolar action plan" describing their conservation strategy for polar bears. The species is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES) meaning international trade, including in parts or derivatives, is controlled by the CITES system of permits and certificates. The United States government has proposed that polar bears be transferred to Appendix I of CITES which would ban all commercial international trade in polar bear parts. The decision to leave the species listed under Appendix II was endorsed by the IUCN and TRAFFIC, who determined that such an uplisting was unlikely