Three species of seal breed on the islands: the southern elephant seal, the Antarctic fur seal, and the Subantarctic fur seal. The waters surrounding the islands are often frequented by several species of whale, especially orcas, which prey on penguins and seals. Large whales such as southern rights and southern humpbacks, and leopard seals are seen more sporadically, and it remains unclear how large or stable their current local populations are, though it is thought their numbers are significantly down compared to the time of first human contact with the islands. The area saw heavy sealing and whaling operations in the nineteenth century and continued to be subject to mass illegal whaling until the 1970s, with the Soviet Union and Japan allegedly continuing whaling operations into the 1990s. Currently, the greatest ecological threat is the longline fishing of Patagonian toothfish, which endangers a number of seabirds that dive into the water after baited hooks.
