Need an example of the effects of overhunting? Look no further than the announcement from the U.S. government that the Caribbean monk seal is officially considered extinct after five years of searching has turned up no trace - not even a mere sighting - of the seals. This is the first seal to disappear completely as a result of human activity.

"Humans left the Caribbean monk seal population unsustainable after overhunting them," Kyle Baker, a biologist for the National Marine Fisheries Service, said in a statement. "Unfortunately, this led to their demise and labels the species as the only seal to go extinct from human causes."

The only subtropical seal native to the Caribbean Sea and Gulf of Mexico, the Caribbean monk seal was discovered on Christopher Colmubus's second voyage in 1494. In fact Columbus may have set a bad precedent, killing eight seals for meat on that journey. Starting in the 1700s and continuing through the 1900s, the seals were "exploited intensively" for their blubber and less commonly, for food, scientific study and zoological collection. The species was listed as endangered in 1967, 15 years after the last confirmed sighting in Seranilla Bank between Jamaica and the Yucatan Peninsula.

The Hawaiian and Mediterranean monk seals are the only two surviving species of monk seal and both are also on the endangered list and on the brink of extinction themselves. The Hawaiian species have less than 1,200 left of their population, while the Mediterranean have dropped to 500.

"Worldwide, populations of the two remaining monk seal species are declining," said Baker. "We hope we’ve learned from the extinction of Caribbean monk seals, and can provide stronger protection for their Hawaiian and Mediterranean relatives."

» MSNBC Environment