MOVEMENTS AND ACTIVITIES OF THE ATLANTIC BOTTLENOSE DOLPHIN, 

 TURSIOPS TRUNCATUS, NEAR SARASOTA, FLORIDA 



A. Blair Irvine,' Michael D. Scott,^ Randall S. Wells,^ and John H. Kaufmann" 



ABSTRACT 



A tagging-observation program was conducted to study the behavioral ecology of Atlantic bottlenose 

 dolphins near Sarasota, Florida. Forty-seven bottlenose dolphins ( 24 males. 23 females) were captured, 

 tagged, and released a total of 90 times from 29 January 1975 through 25 July 1976. Tagged animals 

 were identified durmg regular boat surveys, and information was collected on all individuals and 

 groups encountered. A total of 997 tagged or marked bottlenose dolphins were sighted. A population of 

 bottlenose dolphins was identified m an estuarine-nearshore area extending about 40 km to the south 

 from Tampa Bay and up to 3 km into the Gulf of Mexico. Social organization was characterized by small 

 dynamic gi'oups that appeared to be subunits of a larger socially interacting herd. Average group size of 

 688 groups was 4.8 bottlenose dolphins (standard error = 0.16). Bottlenose dolphins concentrated in 

 different areas seasonally, possibly in response to distribution changes of important prey species. 

 Feeding strategies of the bottlenose dolphins apparently varied according to available water depth 

 and differed from strategies of pelagic small cetaceans. Calving apparently occurred from spring 

 to early fall. 



Until the 1970's, information on the natural 

 history of free-ranging small cetaceans consisted 

 primarily of chance observations (e.g., Norris and 

 Prescott 1961). Increased interest and application 

 of new technology have now greatly expanded our 

 knowledge. Long-term studies of the behavior 

 and ecology of dolphins have been conducted by 

 researchers using boats, submersibles, aircraft, 

 and towers or cliff-top vantage points (see review 

 by Norris and Dohl 1980a). Biotelemetry and 

 newly developed tagging techniques have 

 been used extensively to gather information on 

 delphinid movements, activities, and herd struc- 

 ture (Norris and Pryor 1970; Evans et al. 1971; 

 Perrin 1975; Leatherwood and Evans 1979; Norris 

 and Dohl 1980b). Natural marks that identify 

 individuals have also been used as the basis for 

 field studies of dolphins (Wiirsig and Wiirsig 1977, 

 1979; Shane and Schmidly^) as well as whales 

 (Pike 1953; Payne 1976; Katona et al. 1979; 



'Gainesville Field Station, Denver Wildlife Research Center, 

 412 NE 16th Avenue, Gainesville, FL 32601. 



^Department of Zoology, University of Florida, Gainesville, 

 Fla.; present address: Inter-American Tropical Tuna Commis- 

 sion, c/o Scripps Institute of Oceanography, La Jolla, CA 92037. 



 Department of Zoology, University of Florida, Gainesville, 

 Fla.; present address: Center for Coastal Marine Studies, Uni- 

 versity of California, Santa Cruz, CA 95064. 



Department of Zoology, Universitv of Florida, Gainesville, 

 FL 32611. 



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

 biology ofthe Atlantic bottlenose dolphin, Tursiopstruncatus.m 

 the Aransas Pass area of Texas. Avail. Natl. Tech. Inf Serv., 

 Springfield, Va., as PB-283 393, 130 p. 



Balcomb and Goebel^). Unfortunately, in most 

 studies of free-ranging cetaceans, the age, size, 

 and sex of herd members was usually unknown, 

 and consequently few details about herd structure 

 and social dynamics were collected. 



The research reported here was an 18-mo tag- 

 ging-observation study to collect data on move- 

 ments, home range, herd structure, and habitat 

 use ofthe bottlenose dolphin, Tursiops truncatus , 

 near Sarasota, Fla. (lat. 27°25' N, long. 80°40' W). 

 This area was chosen for several reasons: bottle- 

 nose dolphins were present throughout the year in 

 areas where channels and islands limited their 

 movements to predictable routes (Irvine and 

 Wells 1972); because the area was used by many 

 boaters, discrete use of an observation boat 

 was not likely to affect the bottlenose dolphins' 

 behavior; and mild weather and sheltered waters 

 made year-round observations feasible. The 

 study was intended to provide insights into the 

 ecology of bottlenose dolphins in a bay-estuarine 

 environment. This report is a revision and re- 

 analysis of parts of Irvine et al.^; Wells et al. (1980) 



Manuscript accepted June 1981. 



FISHERY BULLETIN: VOL. 79, NO. 4, 1981. 



«Balcomb,K.C.,III,andC.A. Goebel. 1976. A killer whale 

 studv in Puget Sound. Final Report to the National Marine 

 Fisheries Service, Contract No. NASO-6-35330. Unpubl. rep. 



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

 E. Evans. 1979. Appendix A. A study of the activities and 

 movements of the Atlantic bottlenose dolphin. Tursiops trun- 

 catus. including an evaluation of tagging techniques. Avail. 

 Natl. Tech. Inf Serv, Springfield. Va., as PB-298 042. 54 p. 



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