Manatees can hear boats, so why are they getting hit?

A new study on Manatee hearing shows the giant marine mammals can sense a wide range of pitches, including the sounds made by boats.

The project was led by Mote Marine Laboratory's training and research coordinator Joseph Gaspard in collaboration with a team of scientists, including Dr. Gordon Bauer, professor at New College of Florida.

The study tested the hearing of Buffett and Hugh, the two resident manatees in at Mote.

"We measured the hearing of different frequencies and also their ability at hearing noise," Bauer said.

The purpose of the study was to determine what manatees can hear - and at what pitch - because manatees constantly face a deadly threat from boats.

Researchers used whistles and other pitches to gauge the manatees' reaction and rewarded them with treats.

"If we presented a sound and they detected it, they just went off to their left a couple of feet and touched a paddle," Gaspard said.

So why are the manatees getting hit by boats?

"It's very similar (to us putting) our head under water and we hear a sound, Gaspard said. "We can't tell where it's coming from (and) we can't process it fast enough."

Professor of psychology Gordon Bauer said it's important to study all the factors that affect manatees' hearing.

"What are the circumstances?" he said. "Does it have to do with the depth of the water? Does it have to do with their activities. Are they eating. Are they sleeping at particular times? But the hypothesis that they just can't hear boats does not seem to be true."

"What are the circumstances? does it have to do with the depth of the water? does it have to do with their activities? are they eating? are they sleeping at particular times? but the hypothesis that they just can't hear boats does not seem to be true."

This could mean changes in how manatee protection zones are formed, but more studies are still needed.

One thing researchers are still emphasizing is that a boat traveling slower causes much less harm to a manatee and makes it much easier for the large marine mammal to get out of the way.