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| Dolphin Cay-Atlantis staff transport Rita and her calf Georgie from Nassau to the release location at Great Harbour Cay, Berry Islands. |
Although West Indian manatees occurred historically in The Bahamas, the absence of natural fresh water sources there has long been suspected to be a limiting factor in their population growth. In recent years, it has become more common to spot manatees in The Bahamas. Yet, there remains scant scientific information about how local manatees use habitats in The Bahamas to forage for food and find freshwater. Understanding more about manatee habitat use in The Bahamas is part of a larger USGS effort to understand manatees throughout the region.
Following the recent release of a Florida manatee known as Rita, and her calf Georgie, the U.S. Geological Survey (USGS) has begun working with the Department of Marine Resources, the Bahamas government, and the Bahamas Marine Mammal Research Organisation (BMMRO) to study the movements of the pair. The two manatees were released on April 19 in the Berry Islands, Bahamas after being captured in Nassau and held since last October due to concerns about potential vessel strikes. The tracking study will not only support Bahamian efforts to monitor the animals in the wake of their release, but will provide new information on manatee survival and adaptation throughout The Bahamas.
Rita's history in The Bahamas dates back to November 26, 2009, when she was first sighted in Spanish Wells harbor, North Eleuthera. When photographs of the female manatee were provided to the USGS Sirenia Project, scientists there were able to identify it as MI-028, an adult female Florida manatee that was nicknamed "Rita." The USGS can identify some manatees by their scar patterns and document repeated sighting with dates and locations using a photo-identification database known as MIPS (Manatee Individual Photo-identification System). The system houses records of individuals that are tracked using tell-tale markings such as scars to identify them and compile their life history over time. Rita's own records in MIPS date back to February 1988, when she was documented as an adult residing in Miami, Florida. Periodic sightings through January 2008 revealed she had had at least 7 calves during her 20 years documented in southern Florida.
Seven months after arriving at Spanish Wells, Rita gave birth to a female calf, which later became known as Georgie. The two continued to frequent Spanish Wells harbor until August 2011. A few months later, on October 11, 2011, Rita and Georgie were sighted in Nassau. Due to concern about potential vessel strikes, The Bahamas Department of Marine Resources authorized the Animal Rescue team from Dolphin Cay-Atlantis to capture the manatees, assess their health and hold them until a decision could be made as to their disposition. The two manatees were captured in Nassau harbor on October 15, 2011 and placed at Dolphin Cay-Atlantis. Health assessments conducted at the capture and during their subsequent care at Dolphin Cay indicated that both animals were in good health.
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| Researchers with BMMRO and Atlantis observe the released manatees Rita and Georgie at Great Harbour Cay |
Over the past few decades, the number of manatee sightings in The Bahamas has increased. The origin of some of these individuals has been traced, through MIPS, to Florida, where manatee populations are increasing in some parts of the state (Lefebvre et al 2001). One female manatee named "Gina" has been residing in Great Harbour Cay, Berry Islands, since 1999. Her history has been traced back to Florida, and she has reportedly produced 3 offspring. Most of her offspring are reported to have remained in the area.
The Department of Marine Resources (DMR) and the Government of The Bahamas decided to release Rita and Georgie at Great Harbour Cay in the Berry Islands. Given Rita's history in Miami, Florida, her release in Great Harbour provides scientists with new opportunity to observe how she settles into The Bahamas with her calf. Information from the research will help provide new baseline information for managing The Bahamas manatee population. To monitor their movements and gather information about their habitat use, USGS released the mother and calf with radio tags and will lead efforts to track the tagged manatees. USGS is also training BMMRO staff, Kendria Ferguson, DMR staff, Indira Brown, and Animal Rescue staff from Dolphin Cay-Atlantis on how to track manatees and use the information to assess their adaptations to the region.
Telemetry monitoring enables behavioral observations, associations with conspecifics and periodic visual health assessments. These technologies can also alert agencies to inappropriate movements or other issues requiring rescue response. These monitoring efforts will be based on research technologies and management guidelines currently used to monitor captive-released manatees internationally.
Other components of the study include an effort to evaluate manatee habitat at Great Harbour Cay – creating for the first time a profile of winter temperatures, the types of food available for manatees to forage, and freshwater sources. The study will also photograph individual manatees living in the Cay and in Bullocks Harbour and document their sex and reproductive status. Overall, the work will provide valuable insights into the threats, key resources, and population structure of manatees living in The Bahamas.
The science will also support educational outreach to the local community, to increase awareness about manatee conservation throughout the Bahamas.
Lefebvre, L. W., Marmontel, M., Reid, J. P., Rathbun, G. B., and D. P. Domning. 2001. Status and Biogeography of the West Indian Manatee. In C. A. Woods, & F. E. Sergile, Biogeography of West Indies: Patterns and Perspectives (pp. 425-463). CRC Press.
SESC | Sirenia Project
2201 NW 40th Terrace
Gainesville, FL 32605-3574
Tel: 352-372-2571 or 352-378-8181
Fax: 352-374-8080
Jim Ried: jried@usgs.gov |
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