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Aerial counts keep researchers updated on plight of manatees

Scientists have known for years that not many manatees are left on the face of the Earth.

As death rates soar and birth rates drop, it's clear the endangered species is in a precarious position.

But it's quite another task to figure out just how many manatees are left.

For that, scientists have taken to the air for the last two years in an attempt to count every manatee in waters around Florida.

The results have been surprising. For a long time, researchers thought only about 1,200 manatees were left alive.

But last year, during the first statewide count, aerial survey teams found 1,470 of the slow-moving creatures. Then in January, the second annual count turned up 1,856 manatees.

The count involved 19 teams flying along the east and west coasts of Florida. Researchers wait until during a cold snap to send the teams into the air because that's when manatees move closer to land, seeking the warmth of the natural spring waters.

A favorite spot for manatees to gather in the winter is near the warm springs that bubble in Kings Bay off Crystal River. A team counted more than 200 manatees there in January and another 48 in the Homosassa River farther south.

Scientists are cheered by the manatee counts, but warn that it's not clear yet what the numbers mean.

"It is encouraging," said Bruce Ackerman, a marine mammal biologist with the St. Petersburg office of the state Department of Natural Resources (DNR). "Our previous guesses were a little too conservative."

Ackerman cautions that the results don't mean the manatee population is growing. It means only that scientists were able to find more manatees this year, possibly because of clearer weather and better conditions for the count.

Several counts will be needed over a number of years before scientists will feel confident in drawing a realistic picture of the manatee population.

For now, researchers rely on other signs to determine the condition of the manatee population. And although more manatees were counted this year, researchers believe the population continues to decline. Indications are that manatees are dying more quickly than they can reproduce.

"The number of deaths has gone up. We know that the habitat is getting worse in many areas and there are indications that the amount of reproduction isn't very high, even for them," Ackerman said.

Ackerman said it's clear that the mammals will remain an endangered species. Manatee habitat is disappearing because of water pollution and development, and the mammals have high mortality rates, in part due to collisions with boat propellers.

"We continue to be worried about them," Ackerman said.

Researchers hope to conduct a second survey this month if the weather is cold enough to bring the manatees into the warmer waters.

This is based on a story that appeared earlier in the Times.