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Manatees, now hear this

Year after year, dozens of manatees are killed or injured by boats that run over the animals. Last year, 53 manatees were killed by boats or barges in Florida waters.

With so many injuries, why haven't manatees learned that the sound of an approaching boat means danger?

Two marine biologists believe they have the answer. It's not that manatees are stupid or even too slow. In fact, researchers have found that manatees can be trained and that they can explode with speed when they are startled.

Their problem is hearing.

That's why Edmund Gerstein, director of marine mammal research at Florida Atlantic University in Boca Raton, and Geoffrey Patton, senior biologist at Mote Marine Laboratory in Sarasota, are studying hearing deficiencies in manatees at Lowry Park Zoo.

They hope to find out what manatees can and cannot hear, and perhaps develop a warning system for boats that manatees can detect.

"We don't see dolphins being besieged by motorboats out there," Gerstein said. "The main difference between (dolphins and manatees) in an instant when they're both frightened is probably the dolphin's acute sense of hearing. That's one reason they're probably not getting hit by boats like manatees are."

The research project, which is expected to cost about $200,000, started earlier this month. Part of the financing comes from private donations, and the rest from the sale of manatee license plates and a surcharge on boat registrations.

In the first phase of the two-year project, the researchers are working with two of Lowry Park's resident manatees to try to learn what they can hear. Gerstein compares the process with a grade-school hearing test, in which children raise their hands when they hear sounds transmitted through headphones.

With the help of food treats served as rewards, the researchers hope to train the 1,200-pound manatees to respond by touching paddles submerged in their pool.

Then, using sophisticated equipment on loan from the U.S. Naval Research Laboratory in Orlando, the researchers will transmit varying sound waves through the water.

The manatees will hit a "yes" paddle when they hear a sound, and a "no" paddle when they hear nothing.

Gerstein and Patton completed a similar study in 1987 with Snooty, a manatee living at Bishop Planetarium in Bradenton. They determined that manatees are smart and easily trained and that they have at least some hearing perception.

After determining the hearing range of manatees in a quiet environment, the researchers plan to add background noise to simulate the natural, noisy habitat that manatees encounter in the wild. Their goal is to gain a better understanding of what manatees actually hear as boats approach.

Visitors to Lowry Park will be able to watch the researchers conduct their experiments. Gerstein, who will live in a trailer behind the exhibit for the next two years, said he plans to answer visitors' questions in his spare time.

"There are a lot of things hurting the manatee population, and even if we do find a solution that works so that manatees can evade boats more effectively, they're still faced with a lot of pressures out there," Gerstein said.

"We have a lot of regulations (protecting manatees), but the most effective and motivated animal out there that can save the manatee is the manatee itself."