Study hints at decade of gains for manatees
By CRAIG PITTMAN, Times Staff Writer
GAINESVILLE -- Florida's endangered manatees, the subject of a longstanding feud between environmentalists and boaters, are doing better than they were 10 years ago, according to research presented this week at a once-a-decade gathering of manatee experts.
"They're sure not out of the woods yet, but there are hopeful signs of recovery," said Lynn Lefebvre of the U.S. Geological Survey, who led the conference.
Threats to the manatees' survival continue to grow as well, with steady increases in the number of boats and marinas, a decline in water quality because of increased coastal development and a decrease in the number of power plants that offer them a cold-weather refuge.
The experts' findings are expected to carry weight in the continuing political debate over manatees, which have been on the endangered species list since the list was created three decades ago.
The increasing number of manatees killed by speeding boats led environmental groups to sue state and federal wildlife agencies two years ago, charging the government was not doing enough to protect the placid marine mammal. That resulted in increased boating restrictions.
But then came a backlash among boaters who saw their rights being jeopardized. Adding to the boaters' anger was a survey last year that counted 3,276 manatees swimming in the state's waterways, about 1,000 more than had ever been counted.
That led to demands that the government agencies figure out whether manatees still qualify for listing as endangered, or if their numbers have increased sufficiently to downgrade their legal protections. Both the U.S. Fish and Wildlife Service and the state Fish and Wildlife Conservation Commission are scheduled to consider changing the manatee's status next year.
Despite finding reasons for optimism, the studies presented at the three-day Manatee Population Ecology and Management Workshop this week cautioned against jumping to the conclusion that it's time to declare the manatee safe from extinction.
Federal wildlife officials' latest plan for protecting the manatee says that before they can be taken off the endangered list, the number of adults that survive from year to year must reach 90 percent, and that about 10 percent of the population -- about 200 to 300 -- can die each year without threatening the species' future.
But the agency's own science experts have criticized that plan, saying that a 10 percent annual die-off would likely doom the species to oblivion. They recommended an adult survival rate of 94 percent.
Experts at the conference cautioned against taking the manatee off the list even if it should hit the magic number of a 94 percent adult survival rate.
"We know nothing about the juvenile survival rate, or the sub-adult survival rates, and we have no information on their reproductive rate," said Cathy Langtimm of the U.S. Geological Survey.
Some manatee populations are actually booming, but they tend to be the smallest concentrations. Manatees at Blue Spring and along the St. Johns River, at Crystal River and along the Panhandle coast could easily beat that magic number. The population along the Atlantic coast just meets the 94 percent criteria, according to Langtimm's findings.
One mystery has long been the manatee population in the Tampa Bay area and southwest Florida. Studies by Langtimm and Holly Edwards of the state wildlife commission, unveiled at the conference, found that the adult survival rate in this part of the state is at least 89 percent, and may be as high as 95 percent, although they cautioned that their studies are far from complete and the numbers remain shaky.
One of the more intriguing lines of research, conducted by biologist Meghan Pitchford of the St. Petersburg-based Florida Marine Research Institute, looked at the ages of the dead manatees brought to FMRI from all over the state. Although manatees can live to be 60 and start reproducing by age 5, Pitchford found that nearly three-fourths of the dead females had not lived long enough to have more than one calf.
Among those attending the conference were representatives of both the Save the Manatee Club and the boating rights group Standing Watch who, for perhaps the first time, agreed on something: that too much waterfront development could harm the state's waterways, hurting both manatees and boaters.
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