Manatees are large, herbivorous marine mammals, often called sea cows, found in the shallow, warm coastal waters and rivers of Florida and the Southeastern United States. These gentle giants, characterized by their paddle-like tails and thick, grayish skin, spend their lives grazing on aquatic vegetation. Their slow-moving nature and need for warm water made them susceptible to human impacts. The species’ decline was a gradual process, driven by centuries of unregulated harvesting and the rapid development of Florida’s waterways.
Setting the Stage for Protection
The manatee population began its decline due to widespread, unregulated hunting for its meat, oil, and hides. Historical accounts confirm that manatee meat was prized for sustenance by various groups, including early settlers and the Seminole people in Florida. The thick hide was a marketable commodity, and the oil rendered from the fat was used for fuel.
The first formal attempts at protection began at the state level in the late 19th and early 20th centuries. Florida enacted a law in 1893 making it illegal to kill or capture a manatee without a permit. Despite these early state-level measures, enforcement proved insufficient to stop the population decline as the human population grew. By the mid-20th century, the manatee’s small numbers made it clear that stronger federal intervention was necessary to prevent extinction.
Formalizing the Endangered Status
Federal recognition of the manatee’s situation occurred in 1967, when the Florida manatee was formally listed as an endangered species. This designation was made under the Endangered Species Preservation Act (ESPA) of 1966, the precursor to modern conservation law. The manatee was among the first species placed on this initial federal list, reflecting the severity of its population drop.
The West Indian manatee, which includes the Florida manatee subspecies, was subsequently included when the Endangered Species Act (ESA) of 1973 was passed. This comprehensive legislation prohibits the “taking” of a listed species and requires the development of recovery plans. The listing indicated the species was in danger of extinction throughout all or a significant portion of its range. This federal action made the manatee a high priority for conservation efforts.
Key Factors Driving Population Vulnerability
Although the manatee received federal protection, the causes of mortality shifted from hunting to human-related development and environmental factors. The primary human-caused threat to manatees today is collision with watercraft, commonly known as boat strikes. Manatees are slow-moving and often swim just beneath the surface, placing them directly in the path of fast-moving motorboats. This results in crushing injuries and deep lacerations from propellers.
Manatees rely on warm water refuges during the winter, as they cannot survive prolonged exposure to water temperatures below 68°F. The loss of natural warm springs has led manatees to become dependent on the thermal discharges from power plants. This reliance presents a future threat, as many of these power plants are expected to be decommissioned in the coming decades.
Mass mortality events are also caused by cold stress and toxic algal blooms, such as red tides. Red tides are caused by the microscopic algae Karenia brevis, which produces neurotoxins called brevetoxins. Manatees are poisoned by inhaling aerosolized toxins when they surface to breathe or by ingesting the toxins accumulated in their seagrass food source. These neurotoxins can cause seizures, loss of motor control, and ultimately, drowning.
Current Status and Recovery Efforts
Following decades of protection, the U.S. Fish and Wildlife Service reclassified the West Indian manatee from Endangered to Threatened in 2017. This change reflected a population increase, growing from an estimated 800-1,000 individuals in the 1970s to over 6,000 counted in Florida waters. The “Threatened” status means the manatee is no longer in immediate danger of extinction, but is likely to become endangered without continued protection.
Despite the downlisting, the species faces ongoing challenges. A mass starvation event beginning in late 2020 and 2021 was attributed to the widespread loss of seagrass beds, particularly in the Indian River Lagoon, due to chronic water quality degradation. This led to a record number of manatee deaths and highlighted the fragility of their recovery.
Ongoing recovery efforts focus on maintaining warm-water access and protecting the manatee’s primary food source. State and federal agencies enforce manatee protection zones, which regulate boat speeds in critical habitats, and work to restore degraded seagrass ecosystems. The manatee’s status remains under close review to ensure the long-term survival of the species.