definition an immigrant would have to be absent during 1990-1991 (to clearly 

 establish its prior absence), first identified in 1992 (its year of immigration), and 

 present during 1993-1994. Similarly, an emigrant would have to demonstrate its 

 presence by being seen since the beginning of the study and for at least two 

 consecutive years before disappearing, and remaining absent for at least two years. 

 Given these restrictions, the only year for which such analyses would be possible 

 was 1992. This is the year for which we have the least data available, due to 

 Hurricane Andrew bringing our field season to a premature close. In the absence of 

 meaningful quantitative measures of immigration and emigration, we provide 

 qualitative descriptions of residency and movements between study areas, and we 

 present quantitative estimates of transience. 



Marked dolphins were considered to be "residents" during the survey season 

 if they were identified in at least four of the five survey years. It must be recognized 

 that this definition of residency is limited; the repeated occurrence of these animals 

 during our surveys does not necessarily indicate a year-round presence. 



The incidence of transience was estimated by identifying individuals that 

 were sighted in only one year of the five-year survey period and had no other 

 sighting records in the DBRI database. The incidence of transience was calculated as 

 the proportion of individuals that met the criteria above relative to the total catalog 

 size for each survey year. This rate is probably an overestimate because it may 

 include dolphins that in fact are not transients, but were missed during other 

 surveys, died, or their fins changed without being detected. 



Results 



Survey Effort 



Surveys were conducted during windows of 10-18 days each year (Table 2). 

 The size of the window each year depended on weather and the number of boats 

 available. Weather, including Hurricane Andrew in 1992, adversely affected survey 

 schedules. During the first years of the project, only two boats were used, but in 1993 

 and 1994 three boats were used. Survey effort was measured in two ways. One 

 measure was a count of the number of boat-days. A boat-day was scored when a boat 

 left the dock to search for dolphins. On average, 24 boat-days were spent in the study 

 area each year (range = 16-28 days, Table 2). A more refined measure of survey effort 

 is the number of linear kilometers covered by our survey boats searching for 

 dolphins within the study area. The total number of kilometers surveyed while 

 "on-effort", (under excellent, good, or fair survey conditions, see appendix) are 

 summarized in Table 2, and are presented by region to allow a comparison of 

 within-region effort across years. Differences across years reflect the effects of 

 weather, and the use of variable numbers of boats. 



Dolphins were seen throughout the study area, but they were not uniformly 

 distributed. Larger groups tended to be found in the more open and deeper waters 



