Old Rockledge
Nature

The Brevard County Manatee Sanctuary at Rockledge: Indian River aggregation site

Florida manatees (Trichechus manatus latirostris) aggregate in the Indian River Lagoon at Rockledge during cold weather. The federally-designated sanctuary protects critical habitat. FWC has monitored populations here since the 1970s.

By The Old Rockledge Team
Florida manatee mother and calf
Florida manatee (Trichechus manatus latirostris) mother and calf. The Brevard County Manatee Sanctuary at Rockledge is one of the Indian River Lagoon's main winter aggregation sites. Public domain via Wikimedia Commons.

Florida manatees aggregate in the Indian River Lagoon around Rockledge during cold weather, when water temperatures elsewhere in the lagoon drop below the 68°F threshold that becomes physiologically dangerous for the species. The Brevard County Manatee Sanctuary, a federally-designated protected area, covers a portion of the lagoon adjacent to Rockledge. The Florida Fish and Wildlife Conservation Commission and the U.S. Fish and Wildlife Service have monitored the population here since the 1970s.

What manatees do at Rockledge

The Florida manatee (Trichechus manatus latirostris) is a subspecies of the West Indian manatee. Adults are 9 to 12 feet long, weigh 800 to 1,200 pounds, eat aquatic vegetation, and are obligately warm-water mammals. Below 68°F sustained water temperature, manatees develop cold stress: lethargy, immune suppression, skin lesions, and eventual death if exposure continues.

In Florida winters, manatees migrate to warm-water refugia: natural springs, the warm-water outfalls of power plants, and certain pockets of the Indian River Lagoon where local conditions maintain higher temperatures. Rockledge is one of the lagoon aggregation sites. The combination of lagoon depth, freshwater inflows, and circulation patterns produces relatively stable winter water temperatures that attract manatees from broader regional ranges.

The Rockledge aggregation is not the largest in Florida (the Crystal River and Blue Spring springs sites hold larger winter aggregations), but it’s significant within the Indian River Lagoon system.

Florida manatee (Trichechus manatus latirostris).
A Florida manatee. Rockledge's manatee aggregation runs strongest in winter, when warm-water refuges along the central lagoon concentrate the animals into a few hundred yards of shore. NOAA. Public domain.

The sanctuary designation

The Brevard County Manatee Sanctuary was established under the federal Endangered Species Act and the Marine Mammal Protection Act, with implementation through the State of Florida. The boundaries cover a portion of the Indian River Lagoon adjacent to Rockledge, with specific regulations on boat speed, anchoring, and approach distance to manatees.

Boat speed limits within the sanctuary are typically 25 mph or less in most zones, dropping to “slow speed/no wake” or “idle speed/no wake” in core manatee aggregation areas. Boaters are required to keep a minimum approach distance from manatees and may not pursue, harass, or feed them. Enforcement is by FWC officers, sometimes supplemented by U.S. Fish and Wildlife Service.

The exact boundaries and current regulations are posted at all public boat ramps in the area and at the FWC Indian River Lagoon manatee zone website. Boundaries and zones are updated periodically; the version in force at any given time is the version on the FWC posting.

Population status

The Florida manatee was federally listed as endangered in 1967 (under the predecessor to the Endangered Species Act) and reclassified as threatened in 2017 after sustained population recovery. Statewide population estimates have ranged from a few thousand individuals in the 1990s to recent estimates over 8,000 manatees, though survey methods have changed and direct comparisons are difficult.

The Indian River Lagoon population has had specific challenges. The lagoon’s seagrass beds, which manatees graze, have declined substantially since the 2010s due to a complex combination of fertilizer runoff, septic-tank leakage, urban stormwater pollution, and the resulting algae blooms that block sunlight from reaching seagrass. The seagrass decline has caused episodic manatee starvation events; the most severe occurred in 2020-2022, when hundreds of manatees died of starvation in the Indian River Lagoon.

The 2020-2022 die-off prompted an emergency federal-and-state response, including provisioning of lettuce and other supplemental feed at certain winter aggregation sites (a measure usually avoided because it changes manatee behavior). The seagrass recovery effort is ongoing.

Indian River Lagoon shore.
The lagoon shore through the sanctuary zone. The 2013 and 2021 seagrass collapse events cut the food base manatees depend on, and the Rockledge population has tracked the lagoon-wide decline. National Archives (NARA 7719517). Public domain.

Where to see manatees at Rockledge

Several public access points provide good viewing opportunities during cold-weather aggregation:

  • Rockledge Park, on Riverside Drive: a small park with a walking path along the river. Manatees are sometimes visible from shore during cold weather when they congregate in the deeper channels just offshore.
  • Wuesthoff Park: another riverfront city park with shoreline access.
  • Cocoa Beach Riverfront Park (just north, in Cocoa): broader public access to the lagoon.

Best viewing is December through March, on the days following cold fronts when water temperatures elsewhere have dropped. Manatees become more concentrated and more easily observed during the aggregation windows.

Boat tours operate from Cocoa and Cocoa Beach during winter season and provide closer wildlife viewing under the regulated approach guidelines. Tour operators are licensed and trained on manatee protection rules.

What humans can do (and shouldn’t)

The standard guidance from FWC and USFWS:

  • Don’t approach manatees in the water. Stay back. The federal minimum approach distance is 50 yards by vessel and you shouldn’t swim toward them.
  • Don’t feed manatees. Federal regulation, with fines.
  • Don’t give them fresh water (yes, people sometimes hose down manatees thinking they’re helping; this can be harmful and trains the animals to approach docks, increasing boat-strike risk).
  • Observe speed limits and posted manatee zones. Boat strikes are the largest single human-cause source of manatee mortality.
  • Report injured, dead, or harassed manatees to FWC’s wildlife alert hotline.

The future

The Brevard County Manatee Sanctuary depends on continued seagrass habitat in the Indian River Lagoon. The current seagrass restoration efforts (state-funded, federal-funded, NGO-funded) target several lagoon segments, including portions near Rockledge. Restoration is slow and uncertain. Climate-driven changes to water temperature and freshwater inflow add additional variables.

The legal protection of manatees at Rockledge is robust. The biological viability of manatees at Rockledge depends on whether the lagoon’s ecosystem can stabilize and recover.

Sources