The Caribbean monk seal, West Indian seal or sea wolf (as early explorers referred to it), Neomonachus tropicalis (formerly Monachus tropicalis), was a species of seal native to the Caribbean and is now believed to be extinct. The Caribbean monk seals' main predators were sharks and humans. Overhunting of the seals for oil, and overfishing of their food sources, are the established reasons for the seals' extinction. The last confirmed sighting of the Caribbean Monk Seal was in 1952 at Serranilla Bank, between Jamaica and Nicaragua. In 2008 the species was officially declared extinct in the United States of America after an exhaustive search for the seals which lasted for about five years. This analysis was conducted by the National Oceanic and Atmospheric Administration and the National Marine Fisheries Service. Caribbean Monk Seals were closely related to the Hawaiian monk seals, which live around the Hawaiian Islands and are critically endangered, and Mediterranean monk seals, which are also critically endangered. An estimated 600 Mediterranean monk seals and 1,100 Hawaiian monk seals are alive in the wild.