About 2,500 manatees have died in Florida in the past four years, heightening tension between conservationists and property owners as federal officials prepare to decide whether to down-list the creature to threatened status.

Conservationists say the deaths are evidence of the vulnerability of the walruslike mammals, which were included on the endangered-species list in 1967 because of boat collisions and destruction of sea grasses in the shallow coastal inlets they inhabit.

But owners of waterfront property and businesses filed a lawsuit in April in federal court accusing the U.S. Fish and Wildlife Service of failing to adhere to its own 2007 recommendation that down-listing is warranted because there are now more manatees than ever. Most of the 4,800 pudgy, sea-grass-munching mammals in the U.S. gather each year in Florida.

The agency’s delay in implementing the recommendation prompted the Pacific Legal Foundation to sue on behalf of a group called “Save Crystal River Inc.” “Environmentalists want to turn the entire Crystal River into a sanctuary, which would hurt our clientele,” said Christina Martin, a Pacific Legal Foundation lawyer.

    Most Read Stories

Opponents of down-listing fear that decreasing protection would leave manatees more vulnerable to potentially catastrophic die-offs.

The Fish and Wildlife Service is expected to take comments until Sept. 2, then make a decision within a year.