AERIAL SURVEYS FOR MANATEES AND DOLPHINS IN 

 WESTERN PENINSULAR FLORIDA 



A. Blair Irvine, 1 John E. Caffin, 2 and Howard I. Kochman 1 



ABSTRACT 



Low altitude aerial surveys were conducted to count West Indian manatees, Trichechns manatus, 

 and bottlenose dolphins, Tursiops truncatus, in western peninsular Florida. A total of 554 manatees 

 was observed in 297 groups. Most of the manatees (58.5%) were sighted in the Collier-Monroe 

 Counties in shallow, brackish inshore areas. A total of 1,383 bottlenose dolphins was observed in431 

 herds, including 700 (in 146 herds) in the Gulf of Mexico, 491 (in 185 herds) in bays, and 192 (in 100 

 herds) in marsh-river habitats. 



West Indian manatees, Trichechus manatus, and 

 bottlenose dolphins, Tursiops truncatus, occur in 

 rivers, estuaries, and coastal areas in Florida 

 (Moore 1953; Layne 1965; Hartman 1974 3 ; 

 Irvine and Campbell 1978). Manatees are dis- 

 persed throughout Florida waters during the 

 summer, but concentrate around warmwater 

 sources in winter (Hartman footnote 3; Irvine 

 and Campbell 1978). Aerial surveys indicate that 

 bottlenose dolphins are also well dispersed in 

 coastal waters of Florida (Odell 1976, 1979; 

 Leatherwood 1979; Odell and Reynolds 1980 4 ). 

 However, localized distribution patterns and 

 seasonal changes in distribution and abundance 

 have only been documented in a few areas for 

 manatees (Odell 1976, 1979; Irvine et al. 1978 5 ; 

 Shane 1980 6 ) or dolphins (Odell 1976, 1979; 



'Denver Wildlife Research Center, Gainesville Field Sta- 

 tion, 412 NE. 16th Ave., Room 250, Gainesville, FL 32601. 



2 Denver Wildlife Research Center, Gainesville Field Sta- 

 tion, Gainesville, Fla.; present address: U.S. Forest Service, 

 P.O. Box A.D., Umilla, FL 32702. 



3 Hartman, D. S. 1974. Distribution, status, and conserva- 

 tion of the manatee in the United States. Report to U.S. Fish 

 and Wildlife Service, National Fish and Wildlife Laboratory, 

 Wash., D.C. National Technical Information Service PB 81 

 140725. 



'Odell. D. K., and J. R. Reynolds III. 1980. Distribution 

 and abundance of the bottlenose dolphin, Tursiops truncatus, 

 on the west coast of Florida. Report to the U.S. Marine Mam- 

 mal Commission, Wash., D. C. National Technical Informa- 

 tion Service PB 80-197650. 



5 Irvine, A. B., M.D.Scott, and S.H.Shane. 1978. A study 

 of the West Indian manatee, Trichechus manatus, in the 

 Banana River and associated waters, Brevard County, Florida. 

 U.S. Fish and Wildlife Service, National Fish and Wildlife 

 Laboratory, Final Draft Contract Report to John F. Kennedy 

 Space Center, NASA, Kennedy Space Center, FL 33899. Con- 

 tract No. CC 63426A, KSC-DF-112. 



6 Shane. S. H. 1980. Manatees (Trichechus manatus) in 

 Brevard County, Florida: Abundance, distribution and use of 

 power plant effluents. Report to Florida Power and Light 

 Co., P.O. Box 13100. Miami. FL 33101. Contract No. 61552- 

 86540. 



Shane and Schmidly 1978 7 ; Irvine et al. 1979 8 ). 

 The distribution of manatees and dolphins in 

 various habitat types and salinities in Florida 

 also is unclear. 



More information is needed to serve as a basis 

 for sound conservation and management deci- 

 sions because manatees and dolphins are pro- 

 tected by the Marine Mammal Protection Act of 

 1972; manatees are also protected by the En- 

 dangered Species Act of 1973. Southwestern 

 Florida, encompassing Everglades National 

 Park (ENP; Monroe County) and the Ten Thou- 

 sand Islands (Collier-Monroe Counties), is of 

 particular interest because this area has been 

 relatively unaffected by human development. 

 Abundance, habitat use, and herd size informa- 

 tion is therefore of interest for comparison with 

 more developed areas. 



We conducted a series of aerial surveys from 

 July to December 1979 to examine the distribu- 

 tion and relative abundance of manatees and 

 dolphins from Bayport, Hernando County (lat. 

 28°32'N, long. 82°39'W), Fla., south to Flamin- 

 go Ranger Station (ENP), Monroe County (lat. 

 25°08'N, long. 81°02'W), Fla. 



METHODS 



Surveys were conducted during five periods: 

 24 through 29 July, 6 through 11 and the 17th of 



Manuscript accepted December 1981. 

 FISHERY BULLETIN: VOL. 80, NO. 3 1982. 



7 Shane, S. H., and D. J. Schmidly. 1978. The population 

 biology of the Atlantic bottlenosed dolphin, Tursiops truncatus, 

 in the Aransas Pass area of Texas. Report to U.S. Marine 

 Mammal Commission, Wash., D.C. National Technical In- 

 formation Service PB 283-393. 



8 Irvine, A. B., M. D. Scott, R. S. Wells, J. H. Kaufmann, and 

 W. E. Evans. 1979. A study of the movements and activities 

 of the Atlantic bottlenosed dolphin, Tursiops truncatus, in- 



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