The deep ocean is increasingly recognized as a major global reservoir of the Earth’s biodiversity, comparable to the biodiversity associated with tropical rainforests and shallowwater coral reefs. Though only a small fraction of the oceans’ ecosystems found at depths below 200 meters have been studied, research has revealed remarkably high levels of biodiversity and endemism. Estimates of the numbers of species inhabiting the deep ocean range between 500,000 and 100 million. The development of new fishing technologies and markets for deep-sea fish products have enabled fishing vessels to begin exploiting these diverse but poorly understood deep-sea ecosystems. By far the most widespread activity affecting the biodiversity of these areas on the high seas is bottom trawl fishing. A number of surveys have shown bottom trawl fishing to be highly destructive to the biodiversity associated with seamounts and deep-sea coral ecosystems and concluded that it is likely to pose significant risks to this biodiversity, including the risk of species extinction. The conservation and management of fisheries and the protection of biodiversity within the 200 n.m. Exclusive Economic Zones is largely a matter of coastal state responsibility. However, the international community as a whole has a collective responsibility to ensure the conservation of fish stocks on the high seas and the protection of biodiversity beyond national jurisdiction.