A manatee calf and its mother at Three Sisters Springs in Crystal River, Fla. More than 6,300 of the mammals are thought to live in the state’s waters. (Scott Audette/Reuters)

Manatees — the gentle, roly-poly marine mammals once mistaken by sailors for mythic mermaids — have been classified as endangered by the U.S. Fish and Wildlife Service since 1967. But that classification may soon change, and for the best possible reason: Manatees have been making a comeback.

Citing reduced threats and “significant improvements” in both manatee population numbers and their habitat. conditions, the service last week issued a statement announcing its proposal to change the West Indian manatee’s status from “endangered” to “threatened” under the Endangered Species Act.

The agency recently completed reviewing a petition for the status change by analyzing scientific and commercial data to determine if the West Indian manatee still met the act’s definition of “endangered,’ a term that describes a species “in danger of extinction throughout all or a significant portion of its range,” according to the statement. A “threatened” species, on the other hand, is one that is likely to become endangered in the foreseeable future. [Marine Marvels: Spectacular Photos of Sea Creatures]

What the review found was a rare conservation success story. “Their numbers are climbing, and the threats to the species’s survival are being reduced,” Michael Bean, a Department of the Interior official, said in the statement. Working together, a number of agencies, including the Fish and Wildlife Service and the Florida Fish and Wildlife Conservation Commission, have established more than 50 protected areas for manatees — an effort that played an important part in helping the species recover.

Even the Coast Guard was involved; it worked with the service to patrol the protected areas and prevent trespassing, and to help minimize boat collisions with the manatees.

The West Indian manatee includes two subspecies: the Florida manatee and the Antillean manatee. In 1967, when manatees first gained endangered status, their Florida population numbered in the hundreds. Manatee populations worldwide are now estimated to be around 13,000, with more than 6,300 of them in Florida. That represents a 500 percent increase since 1991, according to the service’s website.

Although the manatee’s future looks brighter than it has for decades, the agency noted that the status change shouldn’t be taken as a sign that conservation work for the species is over. Manatees will continue to enjoy the protection of government agencies and legislation such as the Marine Mammal Protection Act, and efforts will continue to further rebuild “sea cow” populations, manage threats and support their role as a “sentinel species” that serves as an early-warning indicator of environmental disturbances.

“Today’s proposal is not only about recognizing this progress, but it’s also about recommitting ourselves to ensuring the manatee’s long-term success and recovery,” Cindy Dohner, Southeast regional director for the service, said in the statement.

The agency published the status-change proposal in the Federal Register on Jan. 8. A 90-day period follows, during which people may submit information for the service to review before it reaches a final decision.

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