Florida Manatees: A Comprehensive Overview of Research and Conservation Efforts
Examining the Science and Strategies Behind Manatee Conservation
Florida manatees, scientifically known as Trichechus manatus latirostris, are a subspecies of the West Indian manatee and are renowned for their gentle nature and distinctive appearance. Despite their endearing qualities, manatees face significant threats, primarily from human activities and environmental changes. This compilation of articles provides a comprehensive overview of the scientific research and conservation efforts aimed at protecting these vulnerable marine mammals. The studies cited explore various aspects of manatee ecology, behavior, and physiology, as well as the effectiveness of management strategies designed to mitigate the risks they face.
Research highlights the importance of high-quality thermal refuges, such as natural springs and passive thermal basins, which are crucial for the survival of cold-intolerant manatees during winter. Studies on manatee movements and habitat use underline the impact of ambient conditions and human management actions on their behavior, revealing preferences for specific habitats under certain environmental conditions. Population ecology and demographic models provide insights into manatee abundance, survival rates, and the challenges posed by environmental stressors like red tides and cold weather.
Genetic studies emphasize the need for maintaining genetic diversity and connectivity among manatee populations, which is vital for their long-term resilience. Tracking methods, body condition assessments, and stable isotope analyses offer valuable data on manatee health, dietary habits, and habitat utilization, informing effective conservation strategies. Additionally, the evaluation of boat speed restrictions and other protective measures demonstrates the ongoing efforts to reduce human-induced mortality and enhance manatee safety.
The articles collectively underscore the necessity of continued research, habitat conservation, and adaptive management to ensure the survival and recovery of Florida manatees. By understanding the complex interplay between manatees and their environment, these studies guide conservationists and policymakers in making informed decisions to protect this endangered species for future generations.
Manatee Articles & Descriptions
1. Quality of thermal refuges influences use by the cold-intolerant Florida manatee
This journal article investigates how the quality of thermal refuges affects the behavior of the cold-intolerant Florida manatee. The study evaluates two types of thermal refuges—passive thermal basins and natural springs—assessing their usage by manatees based on ambient temperature and refuge quality. The findings underscore the importance of high-quality refuges in supporting manatee populations during cold weather, highlighting implications for habitat conservation and management efforts to maintain adequate thermal environments for this endangered species.
Citation:
Haase, C. G., Fletcher, R. J. Jr., Slone, D., Reid, J. P., & Butler, S. M. (2023). Quality of thermal refuges influences use by the cold-intolerant Florida manatee. Endangered Species Research. U.S. Geological Survey. Retrieved from https://www.usgs.gov/publications/quality-thermal-refuges-influences-use-cold-intolerant-florida-manatee
2. How do ambient conditions and management actions affect manatee movements and habitat use?
This article examines the effects of ambient conditions and management actions on the movements and habitat use of Florida manatees. Conducted in Kings Bay, Florida, the study tracked manatee movements using satellite-linked GPS telemetry from 2006 to 2018. The findings reveal that manatees prefer certain spring basins under specific conditions, such as low tide and colder ambient temperatures. The research highlights the influence of human interaction, noting that manatees used springs more frequently when they were closed to visitors, emphasizing the need for careful management to protect these habitats.
Citation:
Slone, D., Butler, S. M., Reid, J. P., Kleen, J., & Palmer, J. (2023). How do ambient conditions and management actions affect manatee movements and habitat use? Journal of Wildlife Management. U.S. Geological Survey. Retrieved from https://www.usgs.gov/publications/how-do-ambient-conditions-and-management-actions-affect-manatee-movements-and-habitat
3. Population ecology of Florida manatees
This study addresses the population dynamics and ecological challenges facing the Florida manatee. The U.S. Geological Survey, in collaboration with the Florida Fish and Wildlife Conservation Commission and U.S. Fish and Wildlife Service, developed models to estimate manatee abundance and project population trends. These models help assess long-term threats and guide conservation efforts. The research emphasizes the importance of accurate monitoring and predictive modeling in ensuring the survival of this endangered species.
Citation:
Martin, J., Runge, M. C., & Hostetler, J. A. (2019). Population ecology of Florida manatees. U.S. Geological Survey. Retrieved from https://www.usgs.gov/centers/eesc/science/population-ecology-florida-manatees
4. Demographic and population models to assess recovery and status of the endangered Florida manatee
This study, conducted by the U.S. Geological Survey, focuses on developing demographic and population models to assess the recovery and status of the endangered Florida manatee. The research utilizes long-term monitoring data and robust-design mark-recapture models to estimate survival and breeding rates, incorporating environmental factors such as red tide severity and winter cold severity. The findings aim to inform conservation strategies and support decision-making for the management and protection of manatees under the Endangered Species Act.
Citation:
Langtimm, C. A., Kendall, W. L., Beck, C. A., & Kochman, H. I. (2016). Demographic and population models to assess recovery and status of the endangered Florida manatee. U.S. Geological Survey. Retrieved from https://www.usgs.gov/centers/wetland-and-aquatic-research-center/science/demographic-and-population-models-assess
5. Modeling past variation in Florida manatee survival, breeding, and movement rates to establish baselines for aquatic ecosystem and restoration research
This research article by the U.S. Geological Survey explores historical changes in the survival, breeding, and movement rates of Florida manatees. Utilizing long-term monitoring data from the Manatee Individual Photo-identification System (MIPS), the study develops baseline demographic estimates essential for aquatic ecosystem and restoration research. The findings highlight the impact of environmental stressors like red tide and cold weather on manatee populations, aiding in the development of effective conservation strategies and policy-making for habitat protection and species recovery.
Citation:
Langtimm, C. A., Kendall, W. L., Beck, C. A., & Kochman, H. I. (2016). Modeling past variation in Florida manatee survival, breeding, and movement rates to establish baselines for aquatic ecosystem and restoration research. U.S. Geological Survey. Retrieved from https://www.usgs.gov/centers/wetland-and-aquatic-research-center/science/modeling-past-variation-florida-manatee
6. West Indian manatee population genetics
This comprehensive study on the population genetics of the West Indian manatee, including the Florida manatee, highlights the development and implementation of nuclear microsatellite markers on approximately 2,000 individuals. These markers provide crucial genetic fingerprints for mark-recapture studies, enabling conservationists to understand population structure, inbreeding, and breeding patterns. The research also underscores the importance of genetic connectivity among manatee populations, aiding resource managers in their conservation efforts. Future studies will expand this research to include populations in Cuba and Brazil, offering more detailed insights into manatee genetics.
Citation:
Hunter, M. E., Beck, C. A., Bonde, R. K., & Gray, B. A. (2016). West Indian manatee population genetics. U.S. Geological Survey. Retrieved from https://www.usgs.gov/centers/wetland-and-aquatic-research-center/science/west-indian-manatee-population-genetics
7. How do we track manatees?
This article by the Florida Fish and Wildlife Conservation Commission details the methods used to track manatees for conservation and research purposes. It explains the process of capturing and tagging manatees, conducting health assessments, and utilizing various tracking technologies such as GPS, VHF, and satellite transmitters. The study provides insights into the importance of radiotelemetry in understanding manatee movements, habitat use, and health, thereby supporting effective conservation strategies and management decisions.
Citation:
Florida Fish and Wildlife Conservation Commission. (n.d.). How do we track manatees? Retrieved from https://myfwc.com/research/manatee/research/radiotelemetry-tracking/process/
8. Assessing body condition of manatees: Can you really be too fat?
This research by the Physiological Ecology and Bioenergetics Lab at the University of Central Florida investigates the methods used to assess the body condition of manatees. The study compares the effectiveness of two ultrasound instruments, Scanoprobe and Tringa, for measuring blubber depth and lipid content. Results indicate significant differences between ultrasound readings and actual measurements, emphasizing the need for accurate techniques to evaluate the health of manatees. This research is crucial for the successful rehabilitation and reintroduction of rescued manatees.
Citation:
University of Central Florida. (n.d.). Assessing body condition of manatees: Can you really be too fat? Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/assessing-body-condition-of-manatees-can-you-really-be-too-fat/
9. Assimilation efficiency
This research by the University of Central Florida's Physiological Ecology and Bioenergetics Lab examines the assimilation efficiency (AE%) of the West Indian manatee. The study uses manganese and lignin as non-assimilated indirect markers to assess how effectively manatees extract nutrients from their diet. Findings reveal significant differences in AE% between wild and captive manatees, as well as between those consuming freshwater versus marine vegetation. The research highlights the importance of habitat conservation to support manatee dietary needs, especially during cold weather.
Citation:
University of Central Florida. (n.d.). Assimilation efficiency. Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/assimilation-efficiency/
10. Do manatees need to drink fresh water?
This study by the University of Central Florida investigates the osmoregulatory needs of West Indian manatees, focusing on their ability to maintain water balance in different environments. The research involved captive manatees in various conditions, revealing that manatees in salt water require access to fresh or brackish water to meet hydration needs. Manatees do not actively drink salt water, and those in fresh water exhibit higher daily water intake. The findings highlight the importance of freshwater availability for manatee survival and health.
Citation:
University of Central Florida. (n.d.). Do manatees need to drink fresh water? Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/do-manatees-need-to-drink-fresh-water/
11. Lactation and milk composition?
This study by the University of Central Florida's Physiological Ecology and Bioenergetics Lab explores the lactation and milk composition of West Indian manatees. The research, conducted at The Living Seas of Epcot Center, provides insights into the energy transfer and growth rates of manatee calves during the suckling period. Key findings include variations in milk consumption, the role of high-fat milk in calf growth, and the transition to solid foods. This research enhances understanding of manatee reproductive physiology and supports better captive care practices.
Citation:
University of Central Florida. (n.d.). Lactation and milk composition. Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/lactation-and-milk-composition/
12. Digestive efficiencies of ex situ and in situ West Indian manatees (Trichechus manatus latirostris)
This study explores the digestive efficiencies of West Indian manatees in both controlled (ex situ) and natural (in situ) environments. Utilizing manganese as a marker, the researchers found significant differences in digestive efficiencies based on diet, with manatees consuming marine vegetation showing lower efficiencies compared to those consuming freshwater vegetation or lettuce. The findings highlight the importance of dietary assessment in conservation strategies, suggesting the need for large biomass to support manatees, especially during cold weather. This research underlines the necessity of habitat conservation for manatee survival.
Citation:
Worthy, G. A. J., & Worthy, T. A. M. (2014). Digestive efficiencies of ex situ and in situ West Indian manatees (Trichechus manatus latirostris). Physiological and Biochemical Zoology, 87(1), 77-91. University of Chicago. https://www.jstor.org/stable/10.1086/673545
13. Feeding preferences of West Indian manatees in Florida, Belize, and Puerto Rico as indicated by stable isotope analysis
This study applies stable isotope analysis to investigate the feeding preferences of West Indian manatees across different regions. By analyzing carbon and nitrogen isotope ratios in manatee skin and aquatic vegetation, the researchers identified dietary variations among manatees in Florida, Belize, and Puerto Rico. Findings reveal that manatees in Florida have a diverse diet including seagrasses, while those in Belize and Puerto Rico primarily consume seagrasses. This research provides crucial insights into the feeding ecology of manatees, aiding in the development of effective conservation strategies.
Citation:
Alves-Stanley, C. D., Worthy, G. A. J., & Bonde, R. K. (2010). Feeding preferences of West Indian manatees in Florida, Belize, and Puerto Rico as indicated by stable isotope analysis. Marine Ecology Progress Series, 402, 255-267. https://doi.org/10.3354/meps08450
14. Evaluation of the nutrition of Florida manatees (Trichechus manatus latirostris)
This dissertation by Lauren T. Harshaw from the University of Florida provides a comprehensive evaluation of the nutrition of Florida manatees, focusing on the dietary differences between captive and wild populations. It includes quantitative surveys of nutrient intake, digestibility trials, and the analysis of fecal short-chain fatty acids. The study underscores the necessity for dietary adjustments in captivity to mirror the fiber content found in the wild, ensuring the overall health and successful rehabilitation of manatees. This work is pivotal for improving captive care and conservation strategies.
Citation:
Harshaw, L. T. (2012). Evaluation of the nutrition of Florida manatees (Trichechus manatus latirostris). University of Florida. Retrieved from https://ufdc.ufl.edu/ufe0044549/00001
15. So much vegetation but what should I eat?
This article by the University of Central Florida discusses the diverse feeding habits of Florida manatees, focusing on their consumption of aquatic vegetation and occasional terrestrial plants. The study uses stable isotope analysis to determine manatee diets over time, providing insights into habitat utilization. The findings reveal regional dietary variations, with manatees in some areas consuming primarily seagrasses and others freshwater plants. This research is vital for understanding manatee feeding ecology and aiding in the conservation and management of critical habitats.
Citation:
University of Central Florida. (n.d.). So much vegetation but what should I eat? Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/so-much-vegetation-but-what-should-i-eat/
16. Florida manatees Trichechus manatus latirostris actively consume the sponge Chondrilla caribensis
This study applies stable isotope analysis to investigate the feeding preferences of West Indian manatees across different regions. By analyzing carbon and nitrogen isotope ratios in manatee skin and aquatic vegetation, the researchers identified dietary variations among manatees in Florida, Belize, and Puerto Rico. Findings reveal that manatees in Florida have a diverse diet including seagrasses, while those in Belize and Puerto Rico primarily consume seagrasses. This research provides crucial insights into the feeding ecology of manatees, aiding in the development of effective conservation strategies.
Citation:
Fitt, W. (2020). Florida manatees Trichechus manatus latirostris actively consume the sponge Chondrilla caribensis. PeerJ, 8, e8443. https://doi.org/10.7717/peerj.8443
17. Opportunistic carnivory by Florida manatees (Trichechus manatus latirostris)
This study by Sarah S. Courbis and Graham A. J. Worthy explores instances of opportunistic carnivory in Florida manatees. Observations in the Indian River Lagoon documented manatees consuming invertebrates such as barnacles, tunicates, and crabs, challenging the traditional view of manatees as strict herbivores. The findings suggest that manatees may actively seek out animal prey under certain conditions, highlighting the complexity of their feeding ecology and the need for a broader understanding of their dietary habits for conservation efforts.
Citation:
Courbis, S. S., & Worthy, G. A. J. (2003). Opportunistic carnivory by Florida manatees (Trichechus manatus latirostris). Aquatic Mammals, 29(1), 104-107. https://doi.org/10.1578/016754203101023942
18. Analysis of Blue Spring discharge data to determine a minimum flow regime
This report, prepared for the St. Johns River Water Management District, provides a detailed analysis of discharge data from Blue Spring to establish a minimum flow regime. The study highlights the significance of Blue Spring as a critical warm-water refuge for the West Indian manatee. By analyzing historical discharge data and using hydrodynamic modeling, the report recommends a phased minimum flow regime to ensure the spring can continue to support manatee populations during winter. This research is vital for the conservation of manatees and the management of Florida's water resources.
Citation:
Rouhani, S., Sucsy, P., Hall, G., Osburn, W., & Wild, M. (2007). Analysis of Blue Spring discharge data to determine a minimum flow regime. St. Johns River Water Management District. Retrieved from /mnt/data/SJ2007-SP17.pdf
19. Ecological roles and importance of sea cows (Order: Sirenia): a review and prospectus
This comprehensive review by Aaron J. Wirsing and colleagues examines the ecological roles and significance of sirenians, including manatees and dugongs, within aquatic ecosystems. The authors highlight the impacts of sirenian herbivory on macrophyte biomass, productivity, and species composition, as well as their roles in nutrient cycling and habitat modification. The review identifies key knowledge gaps, particularly in understanding the ecological functions of lesser-studied manatee species and the non-consumptive effects of predators. This synthesis underscores the need for further research to inform conservation and management strategies for these important megaherbivores.
Citation:
Wirsing, A. J., Kiszka, J. J., Allen, A.-C., & Heithaus, M. R. (2022). Ecological roles and importance of sea cows (Order: Sirenia): a review and prospectus. Marine Ecology Progress Series, 689, 191-215. https://doi.org/10.3354/meps14031
20. Stable isotope turnover rates and diet-tissue discrimination in the skin of West Indian manatees: Implications for evaluating their feeding ecology and habitat use
This master's thesis by Christy D. Alves investigates stable isotope turnover rates and diet-tissue discrimination in the skin of West Indian manatees. The study provides critical baseline parameters for accurate interpretation of isotopic data, highlighting the slow turnover rates of carbon and nitrogen in manatee epidermis. The findings indicate that stable isotope analysis can effectively summarize long-term dietary intake rather than recent diet, offering valuable insights into manatee feeding ecology and habitat use. This research is essential for improving conservation strategies for these endangered marine mammals.
Citation:
Alves, C. D. (2007). Stable isotope turnover rates and diet-tissue discrimination in the skin of West Indian manatees: Implications for evaluating their feeding ecology and habitat use. University of Central Florida. Retrieved from https://stars.library.ucf.edu/etd/3061
21. When is even Florida not warm enough?
This article by the University of Central Florida's Physiological Ecology and Bioenergetics Lab examines the impact of cold weather on Florida manatees, highlighting their vulnerability to hypothermia during extreme cold events. The study discusses the physiological limitations of manatees, such as low metabolic rates and poor insulation, which contribute to their inability to cope with cold temperatures. The research emphasizes the importance of warm water refugia for manatee survival and the role of maternal teaching in guiding juveniles to these critical habitats.
Citation:
University of Central Florida. (n.d.). When is even Florida not warm enough? Retrieved from https://sciences.ucf.edu/biology/PEBL/current-research/manatee-studies/when-is-even-florida-not-warm-enough/
22. Carcass examinations in the Atlantic Unusual Mortality Event
This report by the Florida Fish and Wildlife Conservation Commission details the findings from carcass examinations during the Atlantic Unusual Mortality Event (UME) starting in December 2020. The UME, primarily caused by starvation due to lack of forage in the Indian River Lagoon, led to significant manatee deaths. The report highlights necropsy findings of chronic starvation, including serous atrophy of fat and muscle tissues, and provides data on mortality rates and contributing factors. This information is crucial for understanding the impacts of habitat degradation on manatee populations and guiding conservation efforts.
Citation:
Florida Fish and Wildlife Conservation Commission. (2023). Carcass examinations in the Atlantic Unusual Mortality Event. Retrieved from https://myfwc.com/research/manatee/rescue-mortality-response/statistics/mortality/ume-carcass/
23. Marine mammals in Mammals of South Asia (pp. 35-50)
This chapter from "Mammals of South Asia" provides an extensive overview of marine mammals in the northern Indian Ocean. It covers the evolutionary history, taxonomy, and anatomy of cetaceans and sirenians, along with their behavior, social organization, and communication methods. The authors highlight the threats to these species, including habitat loss, pollution, and by-catch in fisheries. The chapter also discusses conservation efforts and the need for further research to protect these endangered marine mammals. This comprehensive summary serves as a valuable resource for understanding the ecological roles and challenges faced by marine mammals in South Asia.
Citation:
Sutaria, D., Arthur, R., & Sathasivam, K. (2015). Marine mammals. In Mammals of South Asia (pp. 35-50). Retrieved from https://www.researchgate.net/publication/305680955
24. Body composition and water turnover rates of bottle-fed West Indian manatee (Trichechus manatus) calves
This study by Rudy M. Ortiz and Graham A. J. Worthy investigates the body composition and water turnover rates of bottle-fed West Indian manatee calves in captivity. Using isotopic dilution techniques, the research reveals significant increases in fat mass and water turnover rates as the calves grow. The findings also indicate that manatee calves do not drink salt water but will drink fresh water when available. This data is crucial for developing effective husbandry and rehabilitation practices for this endangered species, highlighting the importance of freshwater access for proper growth and development.
Citation:
Ortiz, R. M., & Worthy, G. A. J. (2006). Body composition and water turnover rates of bottle-fed West Indian manatee (Trichechus manatus) calves. Aquatic Mammals, 32(1), 41-45. https://doi.org/10.1578/AM.32.1.2006.41
25. Measurement of the acoustic reflectivity of sirenia (Florida manatees) at 171 kHz
This study measures the acoustic reflectivity of Florida manatees to evaluate the potential use of active sonar for detecting manatees and reducing boat collisions. Utilizing live animals and tissue samples, the researchers assessed sonic reflectivity and found that manatees reflect substantial amounts of sound, though often in a specular manner. These findings indicate challenges in detecting manatees using sonar at 171 kHz due to specular reflections, suggesting the need for further research into alternative frequencies and detection methods to improve conservation efforts.
Citation:
Jaffe, J. S., Simonet, F., Roberts, P. L. D., & Bowles, A. E. (2007). Measurement of the acoustic reflectivity of sirenia (Florida manatees) at 171 kHz. Journal of the Acoustical Society of America, 121(1), 158-165. https://doi.org/10.1121/1.2384845
26. Brevetoxin-associated mass mortality event of bottlenose dolphins and manatees along the east coast of Florida, USA
This study documents a mass mortality event involving bottlenose dolphins and Florida manatees along the east coast of Florida between October 2007 and January 2008, attributed to a severe bloom of the toxic dinoflagellate Karenia brevis. The research highlights the significant impact of brevetoxin exposure, confirmed through toxin analysis in carcasses. This event underscores the dangers of harmful algal blooms (HABs) to marine mammal populations and the importance of monitoring and managing these environmental threats to protect vulnerable species.
Citation:
Fire, S. E., Flewelling, L. J., Stolen, M., Noke Durden, W., de Wit, M., Spellman, A. C., & Wang, Z. (2015). Brevetoxin-associated mass mortality event of bottlenose dolphins and manatees along the east coast of Florida, USA. Marine Ecology Progress Series, 526, 241-251. https://doi.org/10.3354/meps11225
27. Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris)
This study investigates the stable isotope turnover rates and diet-tissue discrimination in the skin of Florida manatees. By analyzing carbon and nitrogen isotopes, the researchers determined that manatee skin turnover rates are slow, making stable isotope analysis useful for assessing long-term dietary intake rather than recent diet changes. This information is critical for understanding manatee feeding ecology and improving conservation strategies. The research highlights the importance of considering both isotopic discrimination and turnover rates for accurate interpretation of stable isotope data in ecological studies.
Citation:
Alves-Stanley, C. D., & Worthy, G. A. J. (2009). Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris). Journal of Experimental Biology, 212(15), 2349-2355. https://doi.org/10.1242/jeb.027565
28. Florida Manatee Management Plan
The Florida Manatee Management Plan by the Florida Fish and Wildlife Conservation Commission outlines comprehensive strategies to protect and conserve the Florida manatee. The plan includes assessments of threats such as watercraft collisions, loss of warm-water habitats, and red tide. It also details regulatory frameworks, enforcement measures, habitat protection efforts, and public education initiatives. The document emphasizes the need for collaboration among federal, state, and local agencies and highlights the importance of public participation in conservation efforts. This plan serves as a critical guide for ensuring the long-term survival of manatees in Florida.
Citation:
Florida Fish and Wildlife Conservation Commission. (2007). Florida Manatee Management Plan. https://www.nrc.gov/docs/ML1432/ML14328A280.pdf
29. Regional Management Plan for the West Indian Manatee (Trichechus manatus)
This comprehensive regional management plan for the West Indian manatee, developed by Ester Quintana-Rizzo and John Reynolds III under the United Nations Environment Programme, outlines the status, threats, and conservation strategies for the species across the Wider Caribbean Region. It emphasizes the need for collaborative efforts among countries, detailed assessments of manatee populations, habitat protection, and enforcement of protective legislation. The report provides short-term and long-term recommendations for effective conservation, aiming to enhance the management and recovery of this endangered species.
Citation:
Quintana-Rizzo, E., & Reynolds III, J. (2010). Regional Management Plan for the West Indian Manatee (Trichechus manatus). United Nations Environment Programme, Caribbean Environment Programme, CEP Technical Report 48. Retrieved from https://www.car-spaw-rac.org/IMG/pdf/REGIONAL_MANAGEMENT_PLAN_FOR_THE_WEST_INDIAN_MANATEE_Quintana_Rizzo-Reynolds_III_CEP_Technical_Report_48_2010_2.pdf
30. Issues and opportunities associated with using manatee mortality data to evaluate the effectiveness of manatee protection efforts in Florida
This paper by C. Scott Calleson discusses the challenges and potential methods for evaluating the effectiveness of manatee protection zones in Florida. By analyzing mortality data over several decades, the study highlights the complexities of measuring success in reducing boat-related manatee deaths. Despite limitations, the research indicates a significant reduction in boat-related mortality rates in areas with established protection zones. This work underscores the importance of continued monitoring, data collection, and adaptive management strategies to enhance manatee conservation efforts.
Citation:
Calleson, C. S. (2014). Issues and opportunities associated with using manatee mortality data to evaluate the effectiveness of manatee protection efforts in Florida. Endangered Species Research, 26, 127-136. https://doi.org/10.3354/esr00638
31. 2021-2022 statewide abundance estimates for the Florida manatee
This technical report provides updated statewide abundance estimates for the Florida manatee based on aerial surveys conducted in 2021-2022. The study estimates a population of approximately 9,790 manatees in Florida, with detailed regional breakdowns. The report discusses the methodology, including statistical models to account for detection probabilities and habitat stratification. It also highlights the importance of accurate abundance estimates for conservation efforts and the challenges associated with surveying this species. The findings are crucial for informing management strategies and ensuring the long-term protection of manatees.
Citation:
Gowan, T. A., Edwards, H. H., Krzystan, A. M., Martin, J., & Hostetler, J. A. (2023). 2021-2022 statewide abundance estimates for the Florida manatee. St. Petersburg (FL): Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute. Technical Report No. 27. Retrieved from https://f50006a.eos-intl.net/ELIBSQL12_F50006A_Documents/Final_1.5_TR27_231027.pdf
32. Novel lethal clostridial infection in Florida manatees (Trichechus manatus latirostris): Cause of the 2013 unusual mortality event in the Indian River Lagoon
This research article identifies a novel lethal clostridial infection as the cause of the 2013 unusual mortality event (UME) in Florida manatees in the Indian River Lagoon. The study highlights how a shift to a predominantly macroalgal diet due to seagrass loss led to clostridial infections, resulting in significant manatee deaths. Detailed pathological analyses, environmental sampling, and microbiological examinations were conducted over an eight-year period. The findings underscore the importance of habitat management and the need to monitor dietary shifts in marine mammal populations to prevent future UMEs.
Citation:
Landsberg, J. H., Tabuchi, M., Rotstein, D. S., Subramaniam, K., Rodrigues, T. C. S., Waltzek, T. B., Stacy, N. I., Wilson, P. W., Kiryu, Y., Uzal, F. A., & de Wit, M. (2022). Novel lethal clostridial infection in Florida manatees (Trichechus manatus latirostris): Cause of the 2013 unusual mortality event in the Indian River Lagoon. Frontiers in Marine Science, 9, 841857. https://doi.org/10.3389/fmars.2022.841857
33. Stock Assessment Report: West Indian Manatee (Trichechus manatus) Florida Stock
This report by the U.S. Fish and Wildlife Service provides an in-depth assessment of the Florida manatee population. It covers the stock definition, geographic range, population size, trends, and the impacts of human activities and natural factors on manatee mortality. The report includes updated population estimates, highlighting significant threats such as watercraft collisions and habitat loss. It emphasizes the importance of conservation efforts and regulatory measures to protect and sustain the manatee population. This document is crucial for informing management strategies and ensuring the long-term survival of manatees in Florida.
Citation:
U.S. Fish and Wildlife Service. (2023). Stock Assessment Report: West Indian Manatee (Trichechus manatus) Florida Stock. Retrieved from https://www.fws.gov/sites/default/files/documents/stock-assessment-report-west-indian-manatee-florida-stock-2023.pdf
34. Quality of thermal refuges influences use by the cold-intolerant Florida manatee
This study documents the first recorded long-distance migration of a Florida manatee to the Mexican Caribbean. Using photo-identification, researchers matched the individual to a known manatee from Florida, providing insights into manatee migration patterns and potential connectivity between geographically separated populations. The study highlights the importance of international collaboration in manatee conservation and the role of citizen science in monitoring these long-distance movements. This finding expands the understanding of manatee behavior and the need for habitat protection across borders.
Citation:
Castelblanco-Martínez, D. N., Álvarez-Alemán, A., Torres, R., Teague, A. L., Barton, S. L., Rood, K. A., Ramos, E. A., & Mignucci-Giannoni, A. A. (2021). First documentation of long-distance travel by a Florida manatee to the Mexican Caribbean. Ethology Ecology & Evolution, 33(1), 15-26. https://doi.org/10.1080/03949370.2021.1967457
35. Preliminary evidence that boat speed restrictions reduce deaths of Florida manatees
This study examines the effectiveness of boat speed restrictions in reducing watercraft-related deaths of Florida manatees. The research highlights that collisions with boats are a leading cause of manatee mortality, accounting for about 20-33% of annual deaths. The implementation of speed zones in key areas began in 1989, with various speed limits enforced to protect manatees. The study uses data from Sykes Creek and the Barge Canal, showing a significant reduction in manatee deaths following stricter enforcement of slow-speed zones. However, the authors note that compliance rates and proper zone design are crucial for these measures to be effective. The study underscores the need for continuous monitoring and enforcement to ensure the protection of manatees from boat collisions.
Citation:
Laist, D. W., & Shaw, C. (2006). Preliminary evidence that boat speed restrictions reduce deaths of Florida manatees. Marine Mammal Science, 22(2), 472-479. https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2006.00027.x
36. Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold
This study investigates the winter habitat preferences of Florida manatees and their vulnerability to cold stress. It identifies three main types of warm-water refuges: power plant outfalls, natural springs, and passive thermal basins. Using statewide winter counts from 1999 to 2011, the study quantifies the proportion of manatees using these refuges and assesses their effectiveness in preventing cold-stress deaths. The research highlights the importance of natural springs, which offer the best protection against cold stress, and discusses the long-term threats posed by the retirement of power plants. The findings underscore the need for enhanced conservation efforts to protect and maintain warm-water habitats for manatees.
Citation:
Laist, D. W., Taylor, C., & Reynolds III, J. E. (2013). Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold. PLoS ONE, 8(3), e58978. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058978
37. Florida Manatees, Warm-Water Refuges, and an Uncertain Future
This article explores the critical reliance of Florida manatees on warm-water refuges for winter survival, emphasizing the significant threat posed by the potential retirement of power plants and the reduction of natural spring flows. Approximately 60% of manatees use power plant outfalls, while 15% depend on natural springs. The study underscores the urgency for a forward-looking management strategy to maintain these essential habitats. It discusses possible management actions, including the gradual weaning of manatees from plant outfalls, enhancing access to existing warm-water springs, and constructing new thermal refuges. The findings highlight the importance of protecting and maintaining warm-water habitats to prevent significant declines in manatee populations due to cold stress.
Citation:
Laist, D. W., & Reynolds III, J. E. (2005). Florida Manatees, Warm-Water Refuges, and an Uncertain Future. Coastal Management, 33(3), 279-295. https://www.tandfonline.com/doi/abs/10.1080/08920750590952018
38. Endangered, Threatened, and Depleted Marine Mammals in U.S. Waters: A Review of Species Classification Systems and Listed Species.
This comprehensive report, prepared for the Marine Mammal Commission, reviews the classification systems and status of endangered, threatened, and depleted marine mammals in U.S. waters, including the Florida manatee. The document provides a detailed analysis of the Endangered Species Act (ESA), Marine Mammal Protection Act (MMPA), and International Union for Conservation of Nature (IUCN) criteria for listing species. It includes historical data, evaluation methodologies, and recommendations for species protection programs. The report highlights the need for continuous monitoring and adaptive management strategies to address emerging threats and ensure the effective conservation of marine mammal populations.
Citation:
Lowry, L., Laist, D. W., & Taylor, E. (2007). Endangered, Threatened, and Depleted Marine Mammals in U.S. Waters: A Review of Species Classification Systems and Listed Species. Marine Mammal Commission. https://www.mmc.gov/wp-content/uploads/endangered-threatened-depleted-marine-mammals.pdf
39. A Survey of Florida Springs to Determine Accessibility to Florida Manatees (Trichechus manatus latirostris): Developing a Sustainable Thermal Network.
This report, prepared for the U.S. Marine Mammal Commission, investigates the accessibility of various Florida springs to manatees and evaluates the potential for enhancing these habitats to support sustainable thermal networks. The study surveyed 22 springs, assessing environmental variables, manatee use, and accessibility issues. It found that 13 springs had limited accessibility due to obstructions like dams and siltation. The report emphasizes the importance of natural warm-water refuges, especially as man-made sources like power plant outfalls become less reliable. Recommendations include habitat restoration and modifications to improve manatee access to these critical thermal refuges.
Citation:
Taylor, C. R. (2006). A Survey of Florida Springs to Determine Accessibility to Florida Manatees (Trichechus manatus latirostris): Developing a Sustainable Thermal Network. Wildlife Trust. https://www.mmc.gov/wp-content/uploads/florida-springs-accessibility-survey.pdf
40. How do we track manatees?
This comprehensive report, commissioned by the Marine Mammal Commission, provides an in-depth review of protection programs for endangered, threatened, and depleted marine mammals in U.S. waters, including the Florida manatee. It evaluates the effectiveness and cost-efficiency of these programs, detailing the provisions of major federal statutes like the Marine Mammal Protection Act (MMPA) and the Endangered Species Act (ESA). The report covers the status, threats, management frameworks, and critical habitat designations for 22 marine mammal taxa, providing recommendations for improving conservation efforts and addressing emerging challenges. The findings emphasize the need for enhanced protection measures and increased funding to ensure the survival of these vulnerable species.
Citation:
Weber, M. L., & Laist, D. W. (2007). The Status of Protection Programs for Endangered, Threatened, and Depleted Marine Mammals in U.S. Waters. Marine Mammal Commission. https://www.mmc.gov/wp-content/uploads/protection-programs-review.pdf