After 56 years and no Caribbean monk seals in sight, the marine mammal is confirmed extinct.

The Caribbean monk seal is now officially extinct, confirmed the National Oceanic and Atmospheric Administration (NOAA) in early June. The only subtropical seal native to the Caribbean Sea and Gulf of Mexico, it’s also the first type of seal to go extinct from human causes, says NOAA biologists. The seals, which were easy targets for hunters while they rested, birthed or nursed their pups on the beach, were overhunted. The last confirmed sighting of one was in 1952. Caribbean monk seals were first listed as endangered in March 1967, and NOAA has now undergone a five-year review to determine its extinction.

NOAA biologists hope they can learn from the Caribbean monk seal to provide stronger protection for the Hawaiian and Mediterranean monk seals, which are both endangered with populations of 1,200 and 500, respectively.