February 18, 1997
FROM: Bruce Ackerman
RE: Synoptic Manatee Survey, 13 February 1997
Staff of the Florida Department of Environmental Protection's (FDEP) Florida Marine Research Institute (FMRI) coordinated an inter-agency synoptic manatee aerial survey. Most of the counts were made on 13 February, although 5 teams flew on 12 or 14 February 1997, due to staff, aircraft, or weather constraints.
Experienced researchers covered all known manatee winter aggregation sites in Florida and Georgia. Counts were made on Florida's east coast at warm-water sites from Brunswick, Georgia to Ft. Pierce, and contiguously from Ft. Pierce south to the Florida Keys. Sites on the St. Johns River were also surveyed. Counts were made on Florida's west coast at warm-water sites in Wakulla, Citrus, and Levy Counties, and contiguously from Tampa Bay south to Whitewater Bay in the Everglades.
Manatees were counted on 21 survey routes. Seventeen aircraft were used (16 planes, 1 helicopter), with 5 flights including FDEP staff. A total of 27 biologists from 11 state, federal, county and private agencies and universities participated, in the air or on the ground, counting or radiotracking at warm-water sites. Two observers from the Marine Industries Association also flew with FDEP biologists.
During the 13 February survey, 1,709 manatees were counted. These included 791 counted on the east coast (including Georgia and the St. Johns River), and 918 on the west coast. This count was lower than other recent synoptic counts, due mostly to the unusual weather conditions for this survey. A mild cold front following an extended warm period provided warm weather and warm water temperatures. Weather on the chosen day, 13 February, was more windy and cloudy than was desirable. Wind and clouds make it harder to spot manatees.
An unusual number of manatees were seen dispersed far from typical aggregation sites. The extended warm period preceding the count likely allowed animals to disperse far from the warm-water aggregations, making them harder to find and count. High counts occurred at some northern aggregation sites (Crystal River, Tampa Bay, Blue Springs, Titusville), but manatees were seen widely dispersed at many other sites (Charlotte, Lee, Collier, Brevard, Palm Beach, and Broward counties). Unusually high counts were observed in the Homosassa River, Banana River, Dade County, and the Florida Keys, areas with lower use in colder winters.
This count was much lower than the count made in 19-20 January 1997 (total 2,229, east 900, west 1,329), following a strong cold front. That count yielded a record count on the west coast of Florida. The recent count was also much lower than the record high count of the 17-18 February 1996 survey (total 2,639, east 1,457, west 1,182), also made following a strong cold front, but during a rapid warm-up.