Mazzoil, M., S. D. McCulloch and R. H. Defran. 2005. Observations on the site fidelity of bottlenose dolphins (Tursiops Truncatus) in the Indian River Lagoon, Florida. Florida Scientist 68:217-227.


Between July 1996 – October 2001, 190 boat-based photo-identification surveys were carried out on the population of bottlenose dolphins (Tursiops truncatus) in Florida’s Indian River Lagoon. Survey effort varied geographically across and within study years, but was relatively high and consistent (number of surveys = 158, 83%) between 1998 to 2001 in the primary study area (PSA) between Sebastian Inlet in the north to Ft. Pierce Inlet in the south. A total of 336 dolphins were photographically identified, with 149 of these individuals found in the PSA. Evidence for short term fidelity within the IRL was derived from an analysis of 67 dolphins sighted eight or more times. The average site fidelity ratio for these more frequently sighted dolphins was 91%.  Further, 57% of these dolphins were sighted in each of their five (45%) or four (12%) possible sighting years. Evidence for even longer-term site fidelity of 20 y comes from continued sightings across the five-year study period of 11 dolphins marked with freeze brands between 1979 to 1981. In the aggregate, these photo-identification data suggest that a more geographically extensive survey strategy, over a longer time scale is needed to assess important details of the population structure of IRL bottlenose dolphins.

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