Dolphin abundance was estimated as the product of sampling block surface area and the 

 associated density estimate. 



Results 



Transects surveyed during the mortality-event-related surveys totaled 1,845 km. Over 

 2,200 transect kilometers were surveyed during the MEGABORG-related surveys. Forty-nine 

 cetacean herds, all bottlenose dolphins, were sighted during the mortality event investigation 

 surveys. A total of 42 herds of bottlenose dolphins were sighted during the MEGABORG 

 surveys. Two herds of Atlantic spotted dolphins {SteneUa frontalis) and a dolphin that was 

 probably a Risso's dolphin {Grampus griseus) were also sighted. 



Table L Estimates of bottlenose dolphio density and related parameien. 



interval bound, point estimate, and upper 95% interval bound, 

 respectively 



An f(0) of 3.08 km"^ (se = 0.11 km"^) was estimated using the hazard-rate model. 

 The estimated average bottlenose dolphin herd size used for density and abundance 

 estimation ranged from 3.3 to 6.5 dolphins/herd (Table I). The largest herd sighted was of 

 52 bottlenose dolphins. Sighting conditions were less than optimal in block 152 and no 

 bottlenose dolphin herds were sighted. In survey blocks where bottlenose dolphin herds 

 were sighted, estimated dolphin densities ranged from 0.09 dolphins/km^ in the vicinity of 

 the MEGABORG (block "B") to 0.25 dolphins/km^ in block 154 (Table I). 



107 



