which die and sink in waters deep enough to keep decomposition gases in solution should 

 not strand. He also suggested that, because of increased exposure to scavengers and 

 predators, the greater the distance from shore at which an animal dies or is debilitated, the 

 less likely the animal will strand. Because of these factors, it is probably reasonable to 

 assume that most of the animals which strand, died or became debilitated within the bay and 

 inshore zones. 



In the northwestern Gulf, the trends in the bay and inshore zones abundance 

 estimates have a different pattern than that of all zones combined, which essentially reflects 

 the trend of the offshore zone. In the inshore zone, fall had the highest estimated 

 abundance, summer the lowest, and winter and spring had intermediate levels. Using a 95% 

 c.i. criterion, the inshore summer estimated abundance was significantly different from the 

 other seasons, but the other seasons were not significantly different from each other. In the 

 bay zone, winter and fall had the lowest estimated abimdance, with spring and summer 

 having approximately equal, but higher levels. The bay winter estimate was significantly 

 lower than the other seasons, but the other seasons were not significantly different from each 

 other (95% c.i. criterion). If the bay and inshore zones are combined, the apparent trend 

 follows that of the inshore zone. In any case, if the trend in the estimated seasonal 

 abundance does reflect the normal pattern, strandings in the northwestern Gulf peak when 

 abundance in the bay and nearshore zones combined is at intermediate levels and is 

 declining. 



The trends in estimated seasonal abundance in the northeastern Gulf for all zones 

 combined also reflect that of the offshore zone. However, the trend in the inshore zone is 

 similar, with the lowest estimated 

 abundance occurring during the summer 

 and winter. Estimated abundance in the bay 

 zone seems to be constant. Keeping in mind 

 that no spring abundance estimate is 

 available and that seasonal estimates of 

 abundance may not be statistically 

 significant, strandings peak in the 

 northeastern Gulf while the abundance in 

 the bay and nearshore zones combined 

 appears to be declining, which was similar 

 to the pattern in the northwestern Gulf. 



The 1990 point abundance estimates 

 for Block 154 were higher than the 1984 

 point estimates for winter, spring, and fall 

 (Figure 4). Based on the 95% c.i. criterion, 

 the 1990 March estimate was significantly 

 different from only the 1984 spring 

 estimate, while the 1990 June estimate was 



JAN 



MAR 



MAY 



JUN 

 SURVEY MONTH 



AUG 



Figure 4: Estimates of bottlenose dolphin abundance for aerial 

 survey Block 154 (sec Figure 1 for location) (Scolt et al., 1989, 

 and Mullin, this volume). Error bars represent 95% confidence 

 intervals. 



26 



