Franz Josef Land and snow bunting. Some ivory gulls, little auks and Brünnich's guillemots opt to spend the winter on the islands. The polar bear population of Franz Josef Land lies within the Barents Sea subpopulation, which also includes polar bears inhabiting Svalbard and the western coast of Novaya Zemlya. In 2004, the Barents Sea subpopulation was estimated at 2,650. There is also a population of Arctic fox, which typically have their territories near seabird habitats. Being declared as a marine mammal sanctuary, the island has rich biodiversity of rare marine mammals. Three species of seals habit the archipelago. Harp seal is the
Novaya Zemlya Novaya Zemlya. The launch rocket was subsequently deployed to Cuba. 1963 saw the implementation of the Limited Test Ban Treaty which banned most atmospheric nuclear tests. The largest underground test in Novaya Zemlya took place on September 12, 1973, involving four nuclear devices of 4.2 megatons total yield. Although far smaller in blast power than the Tsar Bomba and other atmospheric tests, the confinement of the blasts underground led to pressures rivaling natural earthquakes. In the case of the September 12, 1973, test, a seismic magnitude of 6.97 on the Richter Scale was reached, setting off an 80 million ton