Manatee Conservation — Florida

The Florida manatee (Trichechus manatus latirostris), a subspecies of the West Indian manatee found only in the southeastern United States, is protected under both the federal Endangered Species Act and the Florida Manatee Sanctuary Act of 1978, which designated the entire state as a sanctuary. The Florida Fish and Wildlife Conservation Commission (FWC) 2021–2022 statewide abundance estimate places the population at a 95% credible interval of 8,350 to 11,730 individuals — a range that overlaps with the prior 2015–2016 interval of 7,520 to 10,280, meaning the population trend remains statistically uncertain.

The species occupies marine, brackish, and freshwater coastal and riverine systems throughout Florida, foraging primarily on seagrass beds in shallow near-shore waters. Because manatees cannot tolerate water temperatures below 68°F for extended periods — a consequence of possessing approximately one inch of body fat and a slow metabolic rate, as documented by Florida State Parks — the southern two-thirds of the state constitutes critical winter range, and access to warm-water refuges is essential for winter survival.

Conservation of the Florida manatee intersects state and federal law, water quality regulation, boating policy, coastal development controls, and the future of Florida's natural springs system. The 2020–2022 starvation crisis in the Indian River Lagoon, the subsequent supplemental feeding program, and a April 2025 federal court ruling against the Florida Department of Environmental Protection collectively mark the most consequential period in Florida manatee governance since the species was first federally listed.

The Florida manatee is protected at the federal level by the Marine Mammal Protection Act and the Endangered Species Act, both of which prohibit harassing, hunting, capturing, or killing the animals. In April 2017, the U.S. Fish and Wildlife Service (USFWS) reclassified the Florida manatee from endangered to threatened under the ESA, citing population growth against criteria established in the 2001 Florida Manatee Recovery Plan and noting the minimum count of 8,350 as a marker of recovery progress. The official reclassification rule was published in the Federal Register on April 5, 2017.

At the state level, the Florida Manatee Sanctuary Act (Florida Statute § 370.12) establishes statewide sanctuary protections. FWC administers Manatee Protection Zones — waterway-specific vessel speed restrictions — under authority of Florida Statute § 379.2431. Local governments may establish additional protection zones through ordinance, subject to FWC approval. Vessel speed zones have been implemented since 1979, according to the University of Miami Shark Research and Conservation Program, though enforcement and compliance remain documented challenges. The Save the Manatee Club reports that over 96 percent of all Florida manatees bear boat scars, reflecting near-universal exposure to vessel traffic across the population.

Federal critical habitat for the Florida manatee was originally designated in 1976. In September 2024, USFWS published a proposed rule to revise that designation, organizing the species' range into four regional management units and acknowledging that total seagrass acreage across Florida remains below 1950s levels. The manatee decal program, administered through Florida Tax Collector offices, channels direct public funding to FWC manatee conservation operations.

Prior to 2020, the single-year manatee mortality record in Florida was 830 deaths in 2013, as documented by UF/IFAS Extension. In 2021, mortality reached 1,101 — 1.7 times the prior five-year average, according to Stetson University — prompting FWC to declare an official Unusual Mortality Event (UME). The UME was formally dated December 1, 2020 to April 30, 2022, during which FWC documented 1,255 carcasses and conducted 137 rescues, concentrated on the Atlantic coast. Brevard County was identified as the epicenter; the Save the Manatee Club reports that 744 of the UME deaths occurred in Brevard County alone.

Necropsies confirmed starvation as the predominant cause of death. Each manatee requires approximately 70 pounds of seagrass daily, as reported by Inside Climate News. The Indian River Lagoon — a 156-mile estuary on Florida's Atlantic coast — had lost as much as 99 percent of its seagrass in portions of its northern extent due to decades of nutrient pollution from fertilizer runoff, septic systems, and sewage discharge. UF/IFAS Extension notes that seagrass is slow-growing and may require decades to re-establish.

In response, FWC and USFWS implemented a supplemental feeding trial at the Indian River Lagoon in the winter of 2021–2022, providing romaine and butter-leaf lettuce to starving animals at a temporary feeding station. The trial continued in winter 2022–2023, during which over 399,000 pounds of romaine lettuce were distributed, according to the Marine Mammal Commission. The 2023–2024 winter program was discontinued after FWC determined it was not needed. A Unified Command between USFWS and FWC coordinated response operations, and USFWS provided over $1 million in Prescott Grant Program funding to the Manatee Rescue and Rehabilitation Partnership (MaRRP) — a network including SeaWorld, ZooTampa at Lowry Park, and Mote Marine Laboratory — in 2022. Annual mortality since the UME peak fell to approximately 800 in 2022, 555 in 2023, and 565 in 2024, per FWC mortality statistics.

The Florida manatee's inability to tolerate water temperatures below 68°F makes warm-water refuges a structural requirement for winter survival. Research published in Coastal Management (Taylor and Francis) documents that approximately 60 percent of Florida manatees historically used thermal outflows from 10 power plants statewide as winter refuges, while roughly 15 to 18 percent relied on natural warm-water springs. The Marine Mammal Commission identifies Blue Spring State Park on the St. Johns River in Volusia County and Kings Bay at Crystal River in Citrus County as the two principal natural spring refuges. Three Sisters Springs, within the Crystal River National Wildlife Refuge, has hosted more than 500 manatees during cold weather events. The Marine Mammal Commission also documents spring-enhancement projects including dredging work at Fanning Spring and Chassahowitzka and seagrass replanting at the Weeki Wachee watershed area.

The Coastal Management research identifies power plant retirements as a significant future threat: manatees exhibit strong site fidelity to established warm-water refuges, meaning the loss of a thermal outflow — as Florida's coastal energy infrastructure transitions away from thermal generation — could trigger cold-stress mortality events before natural spring infrastructure can absorb displaced animals. This dependency links manatee conservation directly to Florida utility and energy policy. The U.S. Army Corps of Engineers constructed a thermal refuge at Faka Union Canal in 2015 in recognition of this vulnerability, as the Marine Mammal Commission documents.

Manatee conservation pressures are not uniform across Florida. The Atlantic coast — principally the Indian River Lagoon corridor from Brevard County through the Treasure Coast — has represented the most acute zone of mortality. Brevard County recorded 744 of the deaths attributed to the 2020–2022 UME, according to the Save the Manatee Club, a direct consequence of near-total seagrass collapse driven by nutrient loading into the lagoon. As of May 9, 2025, FWC data reported 363 deaths statewide, with 75 in Brevard County.

Southwest Florida's Charlotte Harbor and Lee County waterways have recorded elevated boat-strike mortality. Vessel strike is documented as the primary human-caused mortality mechanism statewide; blunt force trauma from hull impact is the leading form of injury, per the Save the Manatee Club. The Gulf Coast panhandle and northern Florida waterways see only migratory or warm-season manatee presence, as the species' thermal constraints preclude year-round occupation of those areas.

The natural spring refuge sites define the northern margin of viable winter range. Blue Spring State Park (Volusia County) and Kings Bay (Citrus County) anchor the Atlantic and Gulf coasts respectively. Florida's geological karstic aquifer system — the source of the constant 68–72°F spring temperatures that make these refuges viable — is also subject to groundwater withdrawal pressures from municipal water supply, connecting manatee viability to the broader management of Florida's Floridan Aquifer System.

The 2020–2022 starvation UME was administratively closed on March 14, 2025, by FWC and USFWS after researchers documented no manatee death from starvation linked to a lack of forage for two consecutive years, according to FWC. Agency officials noted the closure as conditional and publicly acknowledged the possibility of future mortality events if water quality conditions deteriorate.

In January 2025, USFWS published a proposed rule in the Federal Register that would retain the Florida manatee's threatened ESA listing while proposing to uplist the Antillean manatee subspecies to endangered. The proposed rule responded to petitions filed in October 2021 and November 2022 by the Center for Biological Diversity, the Harvard Animal Law and Policy Clinic, Miami Waterkeeper, and the Save the Manatee Club. In February 2025, USFWS announced it would not reclassify the Florida manatee to endangered, characterizing the species as one 'likely to become endangered in the foreseeable future.'

In April 2025, a federal judge ruled in Bear Warriors United v. Florida Department of Environmental Protection that Florida DEP must obtain an incidental take permit under the Endangered Species Act related to wastewater discharges into the Indian River Lagoon that contributed to seagrass collapse and manatee deaths, as WUWF reported. The ruling, issued by Judge Mendoza, requires DEP to submit a Habitat Conservation Plan. The court stated that Indian River Lagoon recovery would take at least a decade under current DEP regulations. Florida DEP filed an appeal of the ruling in May 2025. Separately, USFWS's September 2024 proposed revision to the Florida manatee's critical habitat designation — the first revision to the original 1976 designation — remained pending as of May 2025.

Manatee conservation in Florida is structurally linked to several other statewide environmental governance systems. The nutrient pollution driving seagrass collapse in the Indian River Lagoon — principally from fertilizer runoff, septic systems, and municipal wastewater discharge — is the same mechanism responsible for harmful algal blooms, including red tide and cyanobacteria outbreaks, that affect fish populations, shorebirds, and human beach access across Florida's coasts. The Inside Climate News account of the Bear Warriors United litigation frames the Indian River Lagoon as a 156-mile estuary described by federal parties as among the most biodiverse estuaries on the continent.

The warm-water refuge dependency connects manatee viability directly to Florida's natural springs system, which faces groundwater depletion from the Floridan Aquifer System under municipal water demand pressure. At the same time, the retirement of coastal power plants — part of Florida's broader energy transition — threatens to remove the thermal outfalls that historically supported roughly 60 percent of the winter manatee population before natural spring capacity can compensate, as documented in Coastal Management.

The Bear Warriors United ruling, if upheld on appeal, may require Florida DEP to obtain federal ESA incidental take permits and file Habitat Conservation Plans for wastewater discharge practices statewide — a precedent that would extend well beyond manatee conservation to the broader governance of nutrient loading from municipalities, agriculture, and the estimated 2.6 million septic systems operating across Florida. The Florida manatee's ESA status also intersects with national debates over federal habitat designation authority and the scope of the Endangered Species Act itself.