distinguished within a sighting from a high quality photograph but do not 



warrant status as a marked' dolphin in the catalog. 

 Grade-2 - There are photographs of some dolphins with distinctive fins that may be 



in the catalog, but because of the quality of photographs it is not possible to 



make appropriate comparisons with the catalog and make a match or assign an 



identification. 

 Grade-3 - Photographic coverage is known to be incomplete, because all dolphins 



were not approached for photographs, no photos were taken, film did not turn 



out, sighting conditions were poor, etc 



Data Processing 



Sighting data and results from photo-analysis are entered into the Dolphin 

 Biology Research Institute (DBRI) database. As of September 1995, the database 

 includes 10,307 sighting records of dolphin groups from Sarasota Bay, Tampa Bay, 

 Charlotte Harbor and the inshore Gulf waters from 1975 through 1994. We use the 

 FoxBase+/Mac Version 1.1 relational database management system containing 

 dBase programming language that permits us to write specific programs to 

 manipulate the database. A Macintosh IIsi computer is used for data entry and a 

 Macintosh Centris 650 computer is used primarily for data manipulations. 



We defined our dataset based on temporal and geographic criteria. We 

 included sightings collected during the August surveys of 1990, 1991, 1992, 1993, and 

 1994 within the designated boundaries considered to comprise Charlotte Harbor 

 (Figure 1). 



Group size estimates were derived from adjustments of field estimates based 

 on photo-analysis (see Appendix 2). Minimum, maximum, and best field estimates 

 were increased if the sum of the number of positively identified individuals plus 

 the number of "other..." dolphins, plus the number of "clean" dolphins exceeded 

 the original field estimates. The resulting revised minimum, revised maximum, 

 and final best estimates were used in all calculations involving group size. 



Several of the abundance and trend estimates and the power analyses were 

 conducted at the Inter-American Tropical Tuna Commission with a VAX 3100/80 

 micro-computer and a 486 IBM-compatible personal computer. Linear regressions 

 were performed using a SAS procedure (SAS 1989). A FORTRAN program designed 

 for use on IBM-compatible personal computers (TRENDS2; Gerrodette 1993) allowed 

 us to conduct a power analysis to detect trends in abundance (Gerrodette 1987). 



Estimation procedur es: Abundance 



The basic questions considered by this project were: "How many dolphins use 

 the Charlotte Harbor study area during the August survey period, and how does this 

 number vary from year to year?". A closed population was assumed because of the 

 brief period during which the surveys took place each year. There are a variety of 

 ways to calculate indices of abundance of bottlenose dolphins inhabiting Charlotte 



