Snorkelers interact with a Florida Manatee inside of the Three Sisters Springs in Crystal River, Florida, Jan. 15, 2015. Reuters

Manatees — the aquatic mammals also known as "sea cows" — are no longer an endangered species, the U.S. Fish and Wildlife Service announced Thursday. But instead of welcoming the announcement as a cause for celebration, environmental groups were pushing back against the government's new status for manatees.

"We believe this is a devastating blow to manatees," Patrick Rose, Executive Director of the Save the Manatee Club, said in a statement. "A federal reclassification at this time will seriously undermine the chances of securing the manatee’s long-term survival."

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The manatee has long been the poster animal for environmental conservation in Florida, where the species' population fell to just a few hundred in the 1970s. But efforts to save the animal, which included the creation of the Save the Manatee Club by former Florida Sen. Bob Graham and singer Jimmy Buffet in 1981, have helped the manatee rebound. In February, the Fish and Wildlife Service announced it had counted more than 6,000 manatees in Florida waters for the third consecutive year.

"Diverse actions by the Service, Florida Fish and Wildlife Commission, industry, conservation groups and others have helped protect manatee habitat and wintering areas, with notable population increases in recent years," the Fish and Wildlife service said in a statement. But the change in the manatee's status from endangered to threatened under the Endangered Species Act has angered some environmentalists, who say increased killings of manatees, often by boat propellers, were not included in the Fish and Wildlife Service's analysis.

While government officials say federal protections will remain in place for the species, environmentalists feared that a delisting of the animal will hurt conservation efforts, and give the public the impression that the animal is thriving, when it is not.

"Manatees are still in danger. With ongoing threats posed by boat strikes and habitat loss, we don’t support reducing protections through down-listing yet,” Jaclyn Lopez, Florida director at the Center for Biological Diversity, said in a statement.

Property rights and boating groups have been pushing for the delisting of the animal for years, but some saw politics in the timing of the announcement, which came just more than three months into a new presidential administration that has sought to repeal environmental protections.

"With the new federal administration threatening to cut 75% of regulations, including those that protect our wildlife and air and water quality, the move to downlist manatees can only be seen as a political one," Rose said.