The Florida Keys are home to the Florida manatee, a subspecies of the West Indian manatee. This large, herbivorous marine mammal, characterized by its grayish-brown skin and paddle-shaped tail, is a regular fixture in the archipelago’s shallow, protected waters. Manatees are protected by federal and state laws, including the Marine Mammal Protection Act and the Florida Manatee Sanctuary Act. Their presence in the Keys is governed by two fundamental needs: access to warm water and abundant food sources.
Geographic Presence and Seasonal Movement
Manatees are found throughout the Florida Keys, but their distribution shifts noticeably with the seasons. They are generally present year-round in the Keys, taking advantage of the subtropical climate and extensive shallow-water habitats. However, their numbers and concentration become most apparent during the cooler months, typically from November through March.
During the winter, when coastal water temperatures drop below 68°F (20°C), manatees must seek out warmer thermal refugia to prevent cold-stress syndrome. In the Keys, they often aggregate in naturally warmer, shallow basins. The Lower Keys, including areas around Key West and Marathon, often serve as reliable overwintering habitat due to consistently warmer ambient water temperatures compared to northern Florida locations.
Manatees are known to be long-distance seasonal travelers, often returning to the same warm-water sites annually. While they are dispersed in summer, utilizing the entire Keys chain for foraging, cold snaps cause them to concentrate quickly in sheltered canals and basins. This movement ensures they remain within a safe thermal range, which is paramount for their survival.
Essential Habitat Requirements in the Keys
The manatee’s sustained presence in the Keys is directly tied to the availability of two resources: warm water and food. As generalist herbivores, manatees rely on a diet of aquatic vegetation, predominantly seagrass, to sustain their large body mass. The Florida Keys National Marine Sanctuary encompasses one of the world’s largest contiguous seagrass habitats, offering an immense foraging ground.
The three most common seagrass species in the Keys are turtle grass, manatee grass, and shoal grass. Manatees consume all these species, and the expansive, shallow seagrass meadows provide ideal grazing areas. The shallow, protected waters of the Keys’ backcountry bays and tidal creeks are particularly important, offering sheltered areas for foraging and serving as nurseries for mothers and calves.
Manatees favor near-shore marine and estuarine waters that are shallow, calm, and rich in vegetation. The shallow waters around the Keys ensure that sunlight penetrates, allowing seagrasses to thrive. This combination of accessible food and sheltered, warm water makes the Keys an important southern range habitat for the species.
Navigating and Viewing Guidelines
Interacting with manatees in the Keys requires strict adherence to regulations designed for their protection. State and federal laws make it illegal to harass, harm, pursue, touch, or molest a manatee, including prohibitions against feeding them or giving them water. These actions alter their natural foraging behavior and attract them to areas where they may be vulnerable.
Boaters must observe posted Manatee Protection Zones, which mandate reduced speeds to prevent vessel-related collisions, the leading cause of manatee injuries and deaths. These zones include “Idle Speed,” where the boat moves only fast enough to maintain steerage without creating a wake, and “Slow Speed,” where the vessel must be fully off plane and settled in the water.
For passive viewing, whether from a boat or shore, one should never attempt to approach a manatee closer than 50 feet. If a manatee changes its behavior—such as stopping feeding or swimming away—you are too close and must back away immediately. Wearing polarized sunglasses while boating can help spot the animals or the characteristic “swirling” pattern they leave on the surface when they dive. If an injured, entangled, or distressed manatee is spotted, the public should immediately report the location to the Florida Fish and Wildlife Conservation Commission Wildlife Alert number.