Miami ? The Florida manatee, this state’s imperiled environmental icon, last year suffered its most dismal year on record.

Of a population of about 3,200, 416 died in 2006, the highest number of deaths recorded in 30 years of statistics. Many died in collisions with boat propellers.

Now, an internal memo says, the U.S. Fish and Wildlife Service has been drafting plans under which the celebrated marine mammals would lose their protection as an endangered species.

The planned reclassification of the slow-moving sea cows from “endangered” to “threatened” is expected to elicit a barrage of criticism from environmental groups who see it as a part of the Bush administration’s push to poke holes in the Endangered Species Act.

The new status would make it easier to loosen boating speed limits and restrictions on waterfront development that have been instituted to make Florida safe for the species, environmental leaders said.

“This is absolutely the wrong time to downlist manatees,” said Patrick Rose, executive director of the Save the Manatee Club and an aquatic biologist who served as the first federal manatee coordinator. “The terrible thing is, while the last year for manatees was bad, the future could be even worse.”

A memo sent from the U.S. Fish and Wildlife Service to the White House said the agency was going to say that the manatee “no longer meets the definition of an endangered species.”

“In Florida, manatees are exhibiting positive growth rates and high adult survival rates along the entire east coast and in the northwest region,” the memo said. “There is still uncertainty about the status of manatees in the southwest region of the state.”

The agency had reached those conclusions after completing a “Five-Year Review” of manatees. But an agency spokesman, while confirming that the recommendation in the memo, dated March 26, reflected the agency’s thinking at the time, said it was possible it might be altered by the time the review is released later this month.