Longitudinal studies spanning decades allow documentation of long-term residency, site fidelity, behavior, ranging, and association patterns as well as trends in abundance. A lot has been learned about the dolphins that inhabit Sarasota Bay through such long-term studies. Do the dolphins that inhabit the next closest estuary to the south of Sarasota Bay show similar patterns? Research efforts in Charlotte Harbor during 2001-2007 added to a long-term database that was begun in 1970. The Sarasota Dolphin Research Program (SDRP) began tagging efforts in Charlotte Harbor in 1970 and 1971 by tagging five female and four male bottlenose dolphins. A few of these individuals were re-sighted a few weeks after tagging, indicating at least short-term residency. The SDRP conducted opportunistic survey and tagging efforts in Charlotte Harbor in 1982 and 1984 and a few of the individuals photographed and tagged were re-sighted over 20 years later. Dr. Suse Shane began behavioral studies of dolphins in Pine Island Sound in 1985 and continued collecting opportunistic photos through 1996. She shared her photo-id catalog containing 276 marked individuals with SDRP (now archived by SDRP) which allowed us to match 90 individuals photographed during our surveys to her catalog.

        During 1990-1994, 1996, 2001-2004, and 2006, SDRP conducted systematic boat-based surveys in Charlotte Harbor and Pine Island Sound to establish population estimates and trends. With the addition of the photo-id data since 2001 we were able to gain a long-term perspective on the dolphins that use these waters. From a total of 565 boat days in the study area since 1982, 1,157 different marked dolphins were identified within study area boundaries. Of these individuals, 141 were seen once, 797 were seen on 2-9 days, and 249 were seen on at least 10 days. Two hundred and eighteen individuals were observed only within a single year and are considered transients. The remaining 939 individuals were sighted over two or more years and are considered residents. Overall, 30% of dolphins identified in the study area were observed over a ten year period or more and are considered long-term residents. The 249 dolphins re-sighted on ten or more days in the study area were observed over a span of 3-24 years (average =12 years). Most of these individuals (82%) showed strong site fidelity as they were never observed outside of the ~750 km2 study area boundary. Hurricane Charley impacts did not appear to affect individual site-fidelity within the study area. Out of 192 dolphins that were sighted on ten or more days both before and after Hurricane Charley, 94% were re-sighted in the same general region within the study area.
        Funding sources contributing to this long-term project include: Mote Scientific Foundation, the Chicago Zoological Society, Harbor Branch Oceanographic Institution’s “Protect Wild Dolphins” program, Mote Marine Laboratory, the National Marine Fisheries Service, and Earthwatch Institute.