Federal officials have confirmed what biologists have long thought: The Caribbean monk seal has gone the way of the dodo.

Humans hunting the docile creatures for research, food and blubber left the population unsustainable, say biologists who warn that Hawaiian and Mediterranean monk seals could be the next to go.

The last confirmed sighting of a Caribbean monk seal was in 1952 between Jamaica and Mexico's Yucatan Peninsula. The National Oceanic Atmospheric Administration's Fisheries Service confirmed Friday that the species is extinct.

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Kyle Baker, a biologist for NOAA's Fisheries Service southeast region, said the species is the only seal to become extinct from human causes.

The seals were first classified as endangered in 1967, and wildlife experts investigated several reported sightings over the past few decades. But officials determined they were other seal types.

The federal agency says there are fewer than 1,200 Hawaiian and 500 Mediterranean monk seals remaining, and their populations are declining.

"We hope we've learned from the extinction of Caribbean monk seals, and can provide stronger protection for their Hawaiian and Mediterranean relatives," Baker said.

The Hawaiian monk seal population, protected by NOAA, is declining at a rate of about 4 percent annually, according to NOAA.

The agency predicts the population could fall below 1,000 in the next three to four years, placing the mammal among the world's most endangered marine species.

"When populations get very small, they become very unstable," Baker said. "They become more vulnerable to threats like disease and predation by sharks."

Vicki Cornish, a wildlife expert at the Ocean Conservancy, said the fate of the Caribbean monk seal is a "wake-up call" to protect the remaining seal populations.

"We must act now to reduce threats to existing monk seal populations before it's too late," she said. "These animals are important to the balance and health of the ocean. We can't afford to wait."

Monk seals are particularly sensitive to human disturbance. And the sea creatures have been losing their food supply and beaches, officials say.

"Once Hawaii, the Caribbean and the Mediterranean were teeming with fish, but these are areas under severe fishing pressure," Cornish said. "They'll eat almost anything — shellfish or finned fish — but their food supply is waning and they're in competition with man."

The Caribbean monk seal, first discovered during Christopher Columbus' second voyage in 1494, once had a population of more than 250,000. But they became easy game for hunters because they often rested, gave birth or nursed their pups on beaches.

From the 1700s to 1900s, the seals were killed mainly for their blubber, which was processed into oils, used for lubrication and coating the bottom of boats. Their skins were used for trunk linings, clothing, straps and bags.

The endangered Hawaiian monk seals face different types of challenges, including entanglement in marine debris, climate change and coastal development.

About 80 to 100 live in the main Hawaiian Islands and 1,100 in the largely uninhabited Northwestern Hawaiian Islands, a marine national monument.

Biologist Bud Antonelis said NOAA's Fisheries Service has developed a monk seal recovery plan for the Hawaiian monk seals.

"But we need continued support from organizations and the public if we are to have a chance at saving it from extinction," he said. "Time is running out."

As for the Caribbean monk seal, NOAA said it is working to have them removed from the endangered species list.

Species are removed from the list when their populations are no longer threatened or endangered, or when they are declared extinct.