dolphins appeared to be transients. Immigration, emigration, and transience are not 

 major influences on the number of animals present at any given time, but they may 

 be important ecologically by providing a means of genetic exchange between 

 populations, as demonstrated for the Sarasota dolphin community and for Tampa 

 Bay It was not possible to calculate a meaningful mortality rate, but stranding data 

 mirrored patterns of mortality reported from other parts of the central west coast of 

 Florida during the same period. 



We attempted to summarize the components of the interannual differences 

 in abundance estimates. It appears that the increase in abundance from 1992 and 

 1993 may be attributed to a return to presumably normal mortality after high 

 mortality the previous year, a higher-than-normal number of young-of-the-year 

 recorded, a higher-than-normal number of calves recorded after a relatively low 

 number recorded the previous year, and a higher-than-normal number of residents 

 recorded in the area (due to increased movement into the area or more effective 

 photographic effort). These data suggest that conditions in the area improved in 

 1993, particularly in comparison to 1992, with relatively high recruitment and 

 possibly site fidelity, and improved survivorship. 



A number of recommendations were made as a result of the findings of this 

 project. We recommend that monitoring be continued at least annually to track and 

 evaluate the apparent trend. More-intensive surveys would permit more-refined 

 determinations of natality, immigration, emigration, transience, and mortality. 

 Although two or three annual surveys can detect large trends in abundance, this 

 study illustrates the difficulty of interpreting the causes for the abundance changes 

 without more detailed or longer-term information Photo-ID work should be 

 expanded to other seasons to examine previous reports of seasonal fluctuations in 

 abundance Empirical studies designed to identify the appropriate level of effort for 

 mark-recapture surveys should be conducted Photo-ID efforts should be expanded 

 to greater distances offshore and along the coast to examine immigration, 

 emigration, and transience in greater detail Patterns of habitat use in Charlotte 

 Harbor should be examined through integration of GIS habitat data with our 

 sighting data. Efforts should be made to integrate ecological studies of the dolphins 

 of Charlotte Harbor with other research efforts under the National Estuary Program. 

 Dolphin community structure needs to be examined in more detail to define 

 biologically meaningful management units. Existing information on residency, 

 ranging and social patterns, and genetics should be integrated to arrive at population 

 designations. Analysis of community structure is necessary to interpret 

 immigration, emigration, and transience relative to population size. Sample sizes 

 for examination of mt-DNA haplotype distributions in Charlotte Harbor should be 

 augmented through biopsy darting or capture-release efforts The genetics data 

 should be supplemented with telemetry data on movements and additional photo- 

 ID efforts. A correlation between increases in the number of dolphin strandings and 

 the occurrence of red tide blooms suggests that further investigation into the role of 

 red tide in dolphin mortality may be warranted. 



VI 



