(1990) indicated that Tampa Bay would be an excellent case study for photo-ID 

 surveys. 



Photo-ID offers several advantages over aerial surveys for measuring certain 

 population rate parameters. The greatest advantage of using photo-ID methods is the 

 accumulation of information on the occurrence, distribution, and ranging patterns 

 of specific individuals. The ability to recognize individuals over time provides 

 opportunities to estimate abundance using mark-resight methods, to evaluate 

 possible cases of immigration, emigration, or transience, to monitor individual 

 female reproductive case histories, to determine the origins of carcasses for 

 mortality estimates, and to examine community structure (Wells 1986). 



This report summarizes the results of six years of NMFS-sponsored bottlenose 

 dolphin research in Tampa Bay, conducted by Dolphin Biology Research Institute 

 (DBRI) and the Chicago Zoological Society (CZS). Annual photo-ID surveys were 

 conducted during September and October of each year from 1988 through 1993. 

 Photographs and sighting data were collected to examine trends in abundance, 

 natality, mortality, immigration, and emigration. 



Methods 



Study Area 



The Tampa Bay study area includes the enclosed bay waters eastward of the 

 chain of barrier islands at the mouth of Tampa Bay, as well as the shallow Gulf 

 coastal waters and passes immediately surrounding the barrier islands (Figure 1). 

 The region is composed of a variety of habitats and conditions, including highly 

 productive seagrass meadows and mangrove shorelines, deep passes between barrier 

 islands, shallow, sandy Gulf waters, dredged channels, open bays, as well as highly 

 altered and polluted regions. This study area was selected in part because of its 

 proximity to the long-term Sarasota study site (Scott et al. 1990b; Wells 1991). The 

 location facilitated logistics for the field work, because we were able to use an 

 existing field station. Preliminary studies indicated that a number of distinctively 

 marked dolphins inhabited the region, and at least some were present over a number 

 of years (Wells 1986). The ongoing photo-ID research being conducted in the 

 Sarasota waters immediately to the south facilitated examination of immigration and 

 emigration, at least between adjacent regions. 



We have divided the 852-km 2 study area into seven regions for assessment of 

 survey effort (Figure 1). Regions were identified by physiographic and effort 

 criteria. Because of the distances of some parts of the study area from our field 

 stations, it was not possible to survey all or Tampa Bay with uniform effort. The 

 segmentation was done in order to be able to quantify effort in different parts of the 

 study area in an attempt to make the within-region effort comparable across years. 



The southernmost sector, Region 1, includes northern Anna Maria Sound, the 

 Manatee River, and Passage Key Inlet. Water depths range from less than one m 

 nearshore, to 1 2 m in the pass, but generally are 2-4 m. This overlaps the 

 northernmost portion of the long-term Sarasota study area. Immediately to the 

 north, Region 2 includes South Tampa Bay, Southwest Channel, and Terra Ceia Bay. 

 Depths range up to 8 m in the channel, but generally are 3-6 m. Region 3, North 

 Tampa Bay, extends eastward from the Sunshine Skyway Bridge to just west of Egmont 

 Key, and includes the main shipping channel into Tampa Bay. Depths range up to 30 



