Closed Manatee Mortality Event Along The East Coast
The Unusual Mortality Event (UME) from starvation due to seagrass loss affecting manatees along Florida’s East Coast was officially closed on March 14, 2025. The elevated manatee mortality numbers associated with this UME decreased three years ago and researchers have not documented a manatee death from starvation linked to a lack of forage for two years.
In 2021, the Working Group on Marine Mammal Unusual Mortality Events confirmed a significant increase in manatee mortalities along the Atlantic coast met the criteria for a UME and the U.S. Fish and Wildlife Service (USFWS) subsequently issued an official declaration. After reviewing all the data collected during this event, the official dates of the UME were determined as the time between December 1, 2020 and April 30, 2022, during which the unprecedented number of 1,255 manatee carcasses was documented and 137 rescues were conducted along this coast.
The Florida Fish and Wildlife Conservation Commission (FWC) and the USFWS remain deeply committed to manatee conservation and continue to monitor the manatee population, respond to public reports of distressed manatees, and support habitat needs statewide.
Unprecedented Collaborative Effort
Working closely with partners, the USFWS and FWC formed an investigative team to analyze the cause of the UME and determined that starvation due to lack of forage in the Indian River Lagoon (IRL) caused this high mortality. Together, they developed and implemented immediate and long-term response strategies. These strategies include intensive manatee rescue collaboration, aquatic habitat restoration, and enhancements to monitoring efforts. Federal and state funding enabled the agencies to support a thorough investigation including regionally focused aerial surveys, use of satellite-linked GPS radio-tags to monitor manatee movement and habitat use, and ongoing analysis of data used in models to help inform population level impacts. Research and monitoring efforts are essential for evaluating impacts to manatee populations and supporting data-driven conservation and protection measures.
To possibly reduce manatee mortality and the number of manatees in need of rehabilitation, the FWC and the USFWS implemented a supplemental feeding trial during the winter seasons of 2021-2022 and 2022-2023. The trial provided the manatees with additional food in a region severely impacted by the loss of seagrass until they dispersed from their winter warm water sites. Over the course of two years, staff and volunteers supplied at least 600,000 pounds of leafy greens to manatees at the supplemental feeding site.
Since the onset of the UME, the Manatee Rescue and Rehabilitation Partnership (MRP; a cooperative of 24 organizations dedicated to rescuing, rehabilitating, and returning manatees to the wild population) helped to rescue and care for a record number of ill and injured manatees. This partnership went above and beyond to assist USFWS and FWC with the UME response and then to work together to shift stable manatees from critical care facilities to holding facilities (where manatees are no longer in critical condition but still need support prior to release) within the MRP to try to keep critical care space available for other manatees in need of care. Five new manatee rehabilitation partners have been added to this organization. Numerous MRP facilities have received substantial funding from the State of Florida to help with pool and other facility enhancements that will provide greater rehabilitation capacity for manatees in the future.
The UME occurred from December 2020 through April 2022, with peak strandings during the winter months of 2020-2021 and 2021-2022. During the event, there were 1,255 manatee mortalities and FWC, the USFWS, and partners rescued 137 manatees. Even though the volume of mortalities and rescues decreased after April 2022, agency staff and partners continued to monitor regional environmental conditions, to study manatee movement and behavior, to respond to live distressed and injured manatees, and to investigate causes and numbers of mortality.
Current Conditions
Elevated manatee mortality on the Atlantic coast has decreased to levels that are expected when there are no unusual causes of death or events, and manatees appear to be in better physical condition. Researchers have observed mating herds and cow-calf pairs, indicating that reproduction is occurring. This improvement is attributed to the fact that seagrass is slowly recovering in some key areas; however, environmental conditions in portions of the IRL remain a concern. FWC and USFWS managers continue to monitor ongoing threats to manatees in this region and other parts of the state, such as impacts from coastal development and watercraft collisions.
Continued Commitment
The FWC and USFWS will continue to monitor the status of the manatee population and investigate the impact of the significant losses sustained during this UME. The future resiliency of manatees is dependent on factors such as population size, distribution, health, and habitat quality, which are all the focus of conservation work. Habitat restoration, manatee rescues and rehabilitation, and improving access to warm-water sites are examples of ongoing efforts to ensure the recovery and long-term survival of the Florida manatee.
Frequently Asked Questions
- Researchers and managers with the Florida Fish and Wildlife Conservation Commission and U.S. Fish and Wildlife Service have carefully reviewed information and data gathered since the start of the manatee UME along Florida's Atlantic coast in December 2020, including manatee health, behavior and habitat use, and environmental conditions.
- Since late 2023, there have been no further indications that manatees along the Atlantic Coast are in poor or compromised body condition due the historic and significant loss of seagrass in the Indian River Lagoon, which resulted in starvation.
- After April 2022, the elevated number of manatee deaths on the Atlantic Coast decreased to levels that are expected when there are no unusual causes of death or events.
- The last death from starvation linked to a lack of available forage was documented in March 2023.
- The Indian River Lagoon (IRL) provides vital habitat to manatees in all seasons, and certain parts of Mosquito Lagoon, the northern extent of the IRL, have exhibited remarkable seagrass recovery, likely contributing to an overall improvement in manatee body condition.
- Habitat experts are also documenting some improvements in other key areas where seagrass historically occurred.
- The UME occurred between December 1, 2020 and April 30, 2022, during which the unprecedented number of 1,255 manatee carcasses were documented and 137 rescues were conducted along the Atlantic coast.
- The peak times of the UME were during winter, when cold temperatures add an extra stressor to manatees already compromised by starvation. A total of 1,039 out the the 1,255 mortalities occurred during the winters of 2020-2021 and 2021-2022.
- After extensive review of all available data on the UME, the USFWS officially declared the UME closed in a letter dated March 14, 2025.
- Since the winter of 2022-2023, there have been no deaths directly linked to starvation due to a lack of available forage. Manatee mortality numbers are back to a level typically seen in this area.
- A record number of small calf mortality was documented in the IRL in 2024. This was not caused by starvation and was determined to be a sign of reproduction occurring again after it ceased during the UME; it is an example of manatees still being affected after the UME.
- FWC researchers will continue to monitor Atlantic coast manatees for any long-term effects of the UME.
- FWC manatee biologists continue to respond to public reports of distressed manatees and rescue manatees that need assistance.
- Since late 2020, the Manatee Rescue and Rehabilitation Partnership (which includes both the USFWS and FWC) added new manatee rehabilitation facility partners to our network and received significant state and federal funding to address key rehabilitation capacity needs and equipment. These funds have enhanced rescue response and ensured manatees coming into rehab receive the highest quality care.
- Manatee management and research staff from FWC and USFWS are actively implementing the Warm-water Habitat Action Plan to secure a resilient network of warm-water habitat statewide. Current actions include developing warm-water enhancement projects and conducting restoration work at known warm-water sites, such as Blue Spring.
- Staff conduct data collection and monitoring throughout the state to evaluate existing and potential protection zones and countywide manatee protection plans.
- Researchers continue to monitor manatee health closely through examinations of carcasses. In addition, research projects using biological samples collected during the UME and collaborations with health experts are ongoing to further understand the impact of starvation on manatee health and identify any possible long-term health risks.
Visit the Manatee Media Resources Archive page for information related to this event.
- Call FWC’s Wildlife Alert toll-free number: 1-888-404-FWCC (1-888-404-3922) or #FWC or *FWC on a cellphone or text 847411 with keyword “FWC,” followed by the city and/or county and any information if you see a sick, injured, dead or tagged manatee.
- Boaters will find them easier to spot if they wear polarized sunglasses and keep a lookout for signs of manatees such as the circular “footprints” they trace on the top of the water or their snouts sticking up out the water.
- Look, but don’t touch manatees. Keep your distance when boating, even if you are steering a canoe, kayak or paddleboard. Be a good role model for others so that they learn how to watch and enjoy manatees without disturbing the animals.
- The plate you buy matters; support FWC manatee rescues and research. Next time you renew your tag, consider a “Save the Manatee” license plate!
- Show your support for manatee conservation by proudly displaying a manatee decal. These high-quality stickers feature original artwork and are available from your local Tax Collector’s office with a $5 donation.
- The Fish & Wildlife Foundation of Florida offers another way to support.