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Scientists Learn Lessons From Captive Released Manatees

August 28, 1998
United States Geological Survey
As he drifted in the Caribbean waters 20 miles west of the Dry Tortugas, time seemed to be running out for "Mo." Nearly 300 miles from where he started his wayward journey and having lost 180 pounds, Mo was suffering from dehydration and malnutrition.

As he drifted in the Caribbean waters 20 miles west of the Dry Tortugas, time seemed to be running out for "Mo." Nearly 300 miles from where he started his wayward journey and having lost 180 pounds, Mo was suffering from dehydration and malnutrition.

If not for his radio-tracking device, Mo, a captive-reared West Indian manatee, would probably not have survived. U.S. Geological Survey biologist Jim Reid, who led Mo's rescue effort with a field crew from SeaWorld Orlando, said, "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."

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. He was radio-tagged by USGS Florida Caribbean Science Center biologists and released from captivity April 22, 1998, into Crystal River, Fla., near where he was found as a newborn calf in 1994. Mo's release was part of a cooperative study by USGS, U.S. Fish and Wildlife Service, and the Captive Manatee Interagency/Oceanaria Working Group on how manatees fare in the wild after having been held for a long time in captivity.

Locations from his 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 fresh water and other manatees. Fresh water is a necessity for manatees.

When Reid traveled to the Dry Tortugas, he was met June 4 by SeaWorld's aquarium and animal care staff, which happened to be there studying nurse sharks. With help from National Park Service rangers, Mo was found drifting in waters 175 feet deep, 20 miles off the islands. He approached the research boat and was captured with a hoop net. During the night, he was transported to Key West aboard the chartered research vessel Whisker, where he was kept wet on the deck.

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 added, Mo would almost certainly have died without human intervention, given his location, condition and disorientation.

Added USGS biologist Reid: "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."

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. He will have low priority for release in the near future. The decision of when and where he may eventually be re-released will be made by theU.S. Fish and Wildlife Service with input form the Captive Manatee Interagency/Oceanaria Working Group.

Another milestone in the study of released captive manatees occurred May 6 when "Georgia," a 7-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, Fla., State Park personnel and USGS Florida Caribbean Science Center manatee researchers.

Georgia was rescued as an orphaned calf in 1991 and spent almost six years in captivity in SeaWorld Orlando. Georgia was one of many manatee calves brought in as orphans every year. She was released a year ago at Blue Spring Park in central Florida.

"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," Lefebvre said. "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.

As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, to contribute to the conservation and the sound economic and physical development of the nation's natural resources, and to enhance the quality of life by monitoring water, biological, energy, and mineral resources.

Note To News Editors:

Reproducible pictures of Mo, and Georgia and her calf may found at

A fact sheet with more information on manatees and USGS manatee research is available at

This news release and in-depth information about USGS programs may be found on the USGS home page at: To receive the latest USGS news release automatically by email, send a request to . Specify the listserver(s) of interest from the following names: water-pr; geologic-hazards-pr; biological-pr; mapping-pr; products-pr; lecture-pr. In the body of the message write: subscribe (name of listserver) (your name). Example: subscribe water-pr joe smith

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Materials provided by United States Geological Survey. Note: Content may be edited for style and length.

Cite This Page:

United States Geological Survey. "Scientists Learn Lessons From Captive Released Manatees." ScienceDaily. ScienceDaily, 28 August 1998. <>.
United States Geological Survey. (1998, August 28). Scientists Learn Lessons From Captive Released Manatees. ScienceDaily. Retrieved May 28, 2024 from
United States Geological Survey. "Scientists Learn Lessons From Captive Released Manatees." ScienceDaily. (accessed May 28, 2024).

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