Manatees bewilder and surprise scientists

On April 22, USGS biologists satellite tagged and released Mo into Crystal River, Florida, which is near where he was found as a newborn calf in 1994

August 27, 1998
Web posted at: 2:30 PM EDT

By Environmental News Network staff

(ENN) -- Captive manatees that have been released into the wild have bewildered and surprised the scientists who study them.

One manatee roamed hundreds of miles away from normal manatee habitat before it was rescued by researchers and another manatee gave birth to a calf in the wild -- a first for a captive reared female.

Mo, a captive-reared West Indian manatee, was rescued by U.S. Geological Survey biologist Jim Reid and a field crew from SeaWorld in Orlando, Fla., nearly 300 miles from where he was released and had lost 180 pounds. Suffering from dehydration and malnutrition, he is lucky to be alive.

"Mo is one lucky manatee. He was drifting away from land and it was pure luck that the Sea World field crew was available for his rescue," said Reid.

Mo was first rescued in 1994 as an orphaned month-old calf from the Withlacoochee River on the northwest coast of Florida and reared in captivity at SeaWorld Orlando.

On April 22, USGS biologists satellite tagged and released Mo into Crystal River, Fla., which is near where he was found as a newborn calf in 1994.

Locations from the satellite-monitored transmitter showed that Mo remained in the area of his release near the Salt River, a popular manatee area, for two weeks. Then, for the next three weeks, no other satellite-relayed locations were received. Finally, in late May, his transmitter indicated that Mo was about 120 miles off the southwest coast of Florida, well outside normal manatee habitat. By June 3, he was closer to the Dry Tortugas, but still far from feeding areas with access to freshwater and other manatees. Freshwater is a necessity for manatees.

Reid, a field crew from SeaWorld and National Park Service rangers found Mo drifting in waters 175 feet deep, 20 miles off the Dry Tortugas islands. He approached the research boat and was captured with a hoop net. During the night, he was transported to Key West.

Mo weighed 555 pounds when he was saved, down from his release weight of 735 pounds. Alert and active, he was returned to SeaWorld Orlando for further observation and treatment.

"Mo seems to have fared well despite his ordeal and is expected to fully recover," said Dr. Mike Walsh, a SeaWorld Orlando biologist who participated in Mo's rescue. However, Walsh said, Mo would almost certainly have died without human intervention, given his location, condition and disorientation.

"We believe that Mo wandered offshore into deep waters where he drifted south with the currents. After 30 days, he was 284 miles from his release site," said Reid.

Almost 300 manatees have been radio-tracked along Florida's coast in the past 20 years. Mo is the first manatee documented to move so far offshore, more than 60 miles from Key West and more than 120 miles from the Florida peninsula. Mo will have low priority for release in the near future.

Another milestone in the study of released captive manatees occurred May 6 when Georgia, a seven-year-old captive-reared female, gave birth to a calf in the wild. Georgia is the first captive-reared manatee known to have successfully reproduced following her release. Her condition has been followed by Blue Spring State Park personnel in Florida and USGS Florida Caribbean Science Center manatee researchers.

"The birth of Georgia's calf is a landmark event in the captive manatee release program," said Lynn Lefebvre, the leader of the USGS manatee research program, adding that reproduction in the wild is one of the best indicators of successful reintroduction.

"Other captive-reared, female manatees have been released in Florida, but Georgia is the first we have documented to give birth," Lefebvre. She said USGS scientists have observed Georgia engaged in normal nursing behavior and that Georgia and her calf are doing fine.

Georgia and Mo could be described as reflecting the extremes of captive manatee release success and failure, respectively, Lefebvre said.

"Mo's experience reminded us of something we already know about manatees -- expect the unexpected," said Lefebvre. "We were at first incredulous that the satellite tag could still be on the manatee. But all of the satellite-relayed data indicated that it was and there was little doubt in my mind that we had to act quickly to save this manatee, plus learn how well a manatee can handle a month-long offshore trip with no food or fresh water."

On the other hand, Lefebvre said Georgia's successful calving is particularly gratifying because the female manatee was extremely tame and frequently sought human attention before the birth of her calf. It is still too early to tell, but the birth of her calf may have broken this pattern of behavior, assuring Georgia of a future in the wild, as well as a place in manatee history.

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