The Florida manatee, a subspecies of the West Indian manatee, is a large, slow-moving marine mammal with an elongated, round body and paddle-shaped flippers and tail. Manatees are herbivores, feeding solely on seagrass, algae and other vegetation in freshwater and estuarine systems in the southeastern United States. Florida manatees can be found as far west as Texas and as far north as Massachusetts during summer months, but during the winter, manatees congregate in Florida, as they require warm-water habitats to survive. Abundance of the subspecies has increased over the last 30 years, which recently prompted the U.S. Fish and Wildlife Service (FWS) to downlist the West Indian manatee from endangered to threatened. However, due to their slow speed and relatively high buoyancy, manatees are often struck by vessels, which is the primary cause of human-related deaths of the species. Additionally, manatees continue to be threatened by loss of warm-water habitat and periodic die-offs from red tides and unusually cold weather events. Florida manatees are managed jointly by both FWS and the Florida Fish and Wildlife Conservation Commission (FWC).
Abundance and Trends
The total abundance for the Florida manatee population state-wide was revised in December 2018 and is now estimated at 8,810 manatees. This estimate is based on aerial surveys conducted in 2015-2016 and accounts for possible error in the detection of animals using a statistical model developed by FWC’s Fish and Wildlife Research Institute (FWRI). This estimate is higher than previous minimum counts, which were may have been inaccurate since they were based on synoptic surveys that did not account for animals absent from survey sites or not seen by observers. The recent higher abundance estimate also suggests that manatee numbers are steadily increasing in Florida, an indication that manatee conservation measures are contributing to recovery of the population.
The Florida manatee occurs only in coastal and inland waters of the southeastern United States, where it occupies the northern limit of the species’ range. Because prolonged exposure to water temperatures below 18°C (65°F) can be lethal to manatees, Florida manatees are confined largely to the southern two-thirds of the Florida Peninsula in winter. There they aggregate at warm-water springs and thermal outfalls from power plants, or remain along the edge of the Everglades at the southern tip of the state. As water temperatures rise in spring and summer, Florida manatees disperse throughout the state and into neighboring states.
Endangered Species Act listing
The Florida manatee is a subspecies of the West Indian manatee, which, until recently, was listed as endangered under the Endangered Species Act (ESA). However, in 2012, FWS received a petition requesting that all West Indian manatees, including Florida manatees and the second subspecies, Antillian manatees, be reclassified from endangered to threatened under the ESA.
In April 2017, FWS officially downlisted the species. In its final rule, the agency cited that the West Indian manatee had met the downlisting criteria established in the 2001 Florida Manatee Recovery Plan and thus warranted reclassification from endangered to threatened.
What the Commission Is Doing
In response to the 2016 proposed listing change of the West Indian Manatee by the U.S. Fish and Wildlife Service (FWS), we submitted a letter recommending that the two subspecies, the Florida manatee and the Antillean manatee, be considered separately. The Commission noted that despite an increase in the population size of Florida manatees, the growth of the population over the past 30 years has remained slow while manatee mortalities continue to reach record highs. We also expressed our concern with the loss of warm-water habitat due to eventual retirements of power plants over the next 30 to 40 years. This could threaten the future manatee population in Florida and reverse past recovery progress.
In addition, the Commission opposed changing the listing status for Antillean manatees, which, outside of Puerto Rico, continue to face considerable threats from habitat loss and degradation, hunting, fisheries bycatch, pollution, and human disturbance. The Sirenia Specialist Group of the International Union for the Conservation of Nature (IUCN) estimates that only about 2,500 mature Antillean manatees remain and projected that the subspecies would decline by 20 percent over the next two generations (40 years) in the absence of effective responses to current and projected anthropogenic threats.
FWS formally downlisted the West Indian manatee on 5 April 2017. However, the Commission remains committed to engaging with federal, state and local authorities to ensure adequate protections continue for the species and regularly participates in stakeholder meetings hosted by the Florida Fish and Wildlife Conservation Commission (FWC). We continue to support an assessment of the potential harmful impact on manatees of a reduction in warm-water refuges through the retirement of power plants, as well as the effectiveness of boat speed restrictions.
We have also been concerned about the harassment of manatees by swimmers, divers, and kayakers at the Kings Bay warm-water refuge in the town of Crystal River, and particularly at Three Sisters Springs, the site’s largest spring. Parts of Kings Bay, including Three Sisters Spring, are managed as part of the FWS’s Crystal River National Wildlife Refuge. In August 2014, the Save the Manatee Club petitioned the FWS to close Three Sisters to human access during the winter manatee season. In response, we wrote to the FWS in November 2014 noting the urgent need for further steps to reduce harassment in the spring and repeated past recommendations that the FWS adopt a no-touch policy and a minimum approach distance for swimmers.
In early 2015, we conducted a site visit to Crystal River and met with involved federal, state, and local officials as well as local citizens and environmental group representatives to review manatee management efforts and plans at Crystal River. These matters were further considered during the Commission’s 2015 annual meeting. During the winter of 2014-15, Refuge staff temporarily closed Three Sisters Spring to human access on several occasions when high numbers of manatees were present in the spring. In 2017, FWS released an updated management plan for Three Sisters Spring, which includes guidelines to close the spring to public access when water temperatures in the region drop to 17 degrees Celsius.
Commission Reports and Publications
See Florida manatee sections in chapters on Species of Special Concern in past Annual Reports to Congress.
Laist, David W., Taylor, Cynthia, and Reynolds, John E. III. 2013. Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold.
Laist, David W. and Shaw, Cameron. 2006. Preliminary Evidence that Boat Speed Restrictions Reduce Deaths of Florida Manatees.
Laist, David W. and Reynolds, John E. III. 2005. Influence of Power Plants and Other Warm-Water Refuges on Florida Manatees.
Laist, David W. and Reynolds, John E. III. 2005. Florida Manatees, Warm-Water Refuges, and an Uncertain Future.
Lowry, Lloyd, Laist, David W., and Taylor, Elizabeth. 2007. Endangered, Threatened, and Depleted Marine Mammals in U.S. Waters.
Weber, Michael L. and Laist, David W. 2007. The Status of Protection Programs for Endangered, Threatened, and Depleted Marine Mammals in U.S. Waters.
|Letter Date||Letter Description|
|April 8, 2016|
|November 24, 2015|
|September 28, 2015|
|September 4, 2015|
|December 30, 2014|
|November 3, 2014|
|September 2, 2014|
|September 21, 2011|
|August 22, 2011|
|April 26, 2010|
|January 14, 2010|
|October 29, 2009|
|September 10, 2009|
Despite the recent increase in manatee abundance, manatees continue to face numerous threats and experience high levels of mortality. Along the Atlantic coast of Florida, hundreds of manatee carcasses have been recovered since December 2020.. Preliminary data released by FWC reflect that manatee deaths are up 212% for the first few months of 2021compared with the five-year average.
Cold stress poses another threat to manatees and was likely a contributing factor to the increase in manatee mortalities in 2021. As manatees continue to lose warm-water habitat from the destruction of natural springs and the closure of power plants, full recovery of the species becomes more difficult.
In addition, collisions with boats are a frequent and increasing cause of human-related deaths, as propellers and boat hulls can inflict serious or mortal wounds. Vessel-related deaths reached a new peak in 2019, with 137 manatees stuck and killed by boats , which tops the previous record of 124 vessel-inflicted mortalities set in 2018.
Manatees can also be killed by neurotoxins associated with red tides that occur most often in southwest Florida. These toxins can be inhaled when they surface to breathe in affected areas, or ingested when they eat sea grass encrusted with tunicates that accumulate the toxins. In 2018, an unprecedented number of manatees died from a large and persistent red tide outbreak in southwest Florida. Harmful algal blooms are also thought to be a contributing factor to the loss of seagrass in estuaries along the Florida coasts.
Instances of manatee harassment are also a problem in areas of naturally occurring warm-water springs. When humans disturb manatees, it can alter their natural behaviors important for survival.
Current Conservation Efforts
On-the-ground manatee conservation efforts coordinated jointly by FWS and FWC are geared toward continuing to recover manatees and mitigating the impacts of ongoing threats. Such activities include assessing the abundance of the Florida manatee population, tracking manatee movements through photo-identification and satellite-linked radio telemetry, monitoring the effect of temporary power plant shutdowns at plants being converted from oil to gas fired generators, improving conditions and protecting manatees at natural warm water refuges, rescuing and rehabilitating distressed manatees, responding to and investigating manatee mortalities, responding to reports of manatee carcasses, enforcing site-specific boat speed zones, and strengthening management efforts to prevent harassment by divers at Crystal River.