The Florida manatee, a subspecies of the West Indian manatee, is Florida's official marine mammal. These gentle giants can grow to a length of 4.6 m (15 feet) and can weigh up to 1,650 kg (3,630 pounds) as adults. The Florida manatee is listed as "vulnerable" by the International Union for Conservation and Nature (IUCN).
Aerial surveys are used for acquiring information on manatee distribution. These surveys are typically conducted in near-shore waters around the state. Flights are usually 4–6 hours long, and are most commonly flown every two weeks for two years. Most surveys are done from small, four-seat, high-winged airplanes (for example: Cessna 172 or 182) flying at an altitude of 230 m (750 ft) at a speed of 130 km/hr (80 mph). The flights are designed to maximize the manatee counts by concentrating on shallow near-shore waters where manatees and their primary food source, seagrasses, are located. Flight paths curve along parallel to the shoreline, and the airplane circles when manatees are spotted until a count of the number of animals in each group is obtained. Deeper waters are usually not surveyed.
All aerial data are recorded on photocopies of navigation charts and entered into a Geographic Information System (GIS) for spatial analysis.
Manatee survey GIS data were used to calculate the total number of manatees found to be located within the boundaries of each water body. See also, the USGS report and risk assessment methodologies for the Florida manatee at: USGS Research and the FWS Review for Listing the Manatee.