significantly different from the 1984 spring and summer estimates. Based on these surveys, 

 it appears that there may have been more animals in this area during spring and summer 

 of 1990 than during the 1984 sampling period. 



The estimated abundance for Block 153 was also higher for June, 1990, than for the 

 spring and summer 1984 estimates (Figure 5). This is consistent with the pattern observed 

 in Block 154. The estimated abundance for the offshore Block 054 for June, 1990, was 

 significantly higher than the spring 1984 estimate (95% c.i. criterion), and was higher but not 

 significantly different from the the summer 1984 estimate (Figure 6). In fact, the June, 1990, 

 estimate was about 20 times higher than the spring 1984 estimate. Similarly, the summer 

 1984 estimate was about 11 times higher than the spring 1984 estimate. This could indicate 

 that the pattern observed in 1984 (higher 

 summer abundance in Block 054) was 

 evident again in 1990. The 1990 estimates 

 for these adjacent blocks (153, 154, and 

 054) were consistently higher than the 

 estimates from 1983-84. It is important to 

 note that the boundaries between the 

 inshore and offshore blocks were not based 

 on any known distribution patterns of the 

 Gulf bottlenose dolphins. The available 

 survey results indicate that the distribution 

 of these dolphins was more or less 

 continuous from the shore out to at least 

 the seaward boundary of the offshore 

 zones. 



MAY 



JUN 



JUL 



SURVEY MONTH 

 Figmc S: Estimaies of boKlenose dolphin abundance for aerial 



The results of these aerial surveys 

 were similar to those conducted prior to the 

 1987-88 east coast bottlenose dolphin 

 dieoff. Keinath and Musick (1988) reported 

 that the results of nearshore aerial surveys 

 along the Virginia coast suggested 

 bottlenose dolphin densities were higher 

 during the dieoff than previous years (1980- 

 86). However, Scott and Bum (1987) 

 reported that their analysis of surveys 

 conducted during the dieoff along New 

 Jersey and Virginia out to the 1000 fathom 

 isobath indicated there was a 60% chance 

 of decline in the offshore stratum 

 abundance ind'jx, as compared to the 1980- 

 81 abundance index. Data were insufficient 

 to evaluate the nearshore stratum (Scott 



survey 

 MuUin, 

 intervals 



Blodc 153 (see Figure 1 for location) (Scott et al., 1989; 

 this volume). Error ban represent 95% confidence 



z 



3 



JUN 

 SURVEY MONTH 



JUL 



Figure 6: Estimates of bottlenoae dolphin abundance for aerial 

 survey Block 054 (see Figure 1 for location) (Scott cl aL, 1989; 

 Mullin, this volume). Error bar* represent 95% confidence 

 intervals. 



27 



