Mark-recapture surveys implementing photographic identification techniques were used to estimate the abundance of bottlenose dolphins in an area of the Big Bend of Florida, stretching from St. Vincent Sound to Alligator Harbor, in the summer of 2007 and winter of 2008. The current population size of individuals in this region is unknown as the most recent abundance estimates were calculated based on aerial surveys conducted in 1993. Recent large scale mortality events, together with an increasing potential for human impacts in this area, warrant an updated and increased understanding of the abundance and stock structure of dolphins in this region. Because the region is large and recent work here suggests that at least two distinct communities exist in these waters, the region was divided into the two areas in which these communities appear to reside (St. Vincent Sound/Apalachicola Bay and St. George Sound/Alligator Harbor) and independent estimates of abundance were calculated for each area and each season. Closed-population models in the program CAPTURE were used to derive the estimates of abundance and the assumptions underlying each model were examined. The estimates calculated from the models selected as being the most appropriate for each data set were similar for each survey area for each season: in the St. Vincent Sound/Apalachicola Bay survey area 182 ± 58 animals inhabited the survey area in the summer and 178 ± 77 animals in the winter; in the St. George Sound/Alligator Harbor survey area 365 ± 164 animals inhabited the survey area in the summer and 359 ± 87 animals in the winter. Results from this study also provided further evidence that at least two communities reside in these waters as only 2.4% of animals captured during the study were captured in both survey areas. If indeed two communities exist in these waters, it appears that site-fidelity and/or residence patterns of individuals may differ between them; in the St. Vincent Sound/Apalachicola Bay survey area 49.6% of the total animals captured were captured more than once and 29.6% were captured both seasons, while in the St. George Sound/Alligator Harbor survey area 35.3% were captured more than once and 13.8% of animals were captured both seasons. In addition, it appears that the St. George Sound/Alligator Harbor survey area supports a greater number of transient animals than the St. Vincent Sound/Apalachicola survey area (46.1% of distinctive animals were seen only once versus 29.9% respectively). This may be due in part to this survey area being more accessible to the open waters of the Gulf of Mexico than the St. Vincent Sound/Apalachicola Bay survey area, which is more protected by barrier islands. The results provided here can be used by the National Marine Fisheries Service to aid in their stock-assessment process and help in the management of the animals in this region.
|Degree||Master of Science, Oceanography|
|Notes||This thesis was found at Florida State University DigiNole Commons: http://diginole.lib.fsu.edu/|
|University||Florida State University|
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