distribution and the geographic features of an area is reflected in Maps 6 and 7. The 

 abundance of sightings in nearshore waters during this survey was further accentuated by 

 the study design. The daily flight pattern included six flight segments (75%) within 111 km 

 of the coast and two flight segments (25%) 112 to 222 km from the landward margin of 

 the survey subunit. Since each survey segment was of equal length, inshore areas (i.e., 

 to 111 km offshore) were surveyed with three times the intensity of those offshore (112 to 

 222 km offshore). Such a hierarchical sampling regime will potentially allow 

 determination of sampling efficiency in the two levels of effort. The relative sampling 

 effort has been considered in formulating conclusions from the data set. 



Mammals in STEX 



No bottlenose dolphins were sighted in STEX subunits during August, but 10 groups 

 were observed in inshore waters of less than 60 m depth (x = 45 m) during November (Map 

 8). Of the unidentified dolphins seen during August, only one of eight (12.5%) was in 

 water less than 50 m in depth (Map 9). The remainder, 87.5%, were beyond the 100-m 

 contour and over 100 km from shore. All of the unidentified Stenella observed were at or 

 beyond the 100-m contour and up to 200 km offshore (Map 9). Of the three groups of 

 unidentified dolphins seen in November, all were confined to the southern margin of the 

 survey subunit near the U.S. /Mexican territorial limit. They were equally distributed in 

 shallow, moderate, and deep water areas (Map 10). 



Short-finned pilot whales were seen in waters approximately 700 m deep during 

 August and November (Map 11). They apparently occurred further inshore than sperm 

 whales, unidentified beaked whales, and other unidentified whales seen during August 

 (Map 12). 



Mammals in NTEX 



Bottlenose dolphins were distributed in nearshore waters of less than 60 m during 

 August (Map 13). Unidentified dolphin groups extended further offshore during the same 

 period (Map 14). The mean depth for bottlenose dolphins was 39 m, whereas 30% of the 

 unidentified dolphin groups were beyond the 200-m contour. This suggests that some of 

 the unidentified dolphin groups represented species other than bottlenose dolphins. Two 

 groups of unidentified Stenella were between the 50- and 100-m contours (Map 14), a 

 striped dolphin group was sighted inside the 50-m depth contour (Map 15), and spotted 

 dolphins, spinner dolphins, and saddleback dolphins were in waters from 100 to 1,000 m in 

 depth (Map 15). 



A single group of sperm whales (three females and one calf) was sighted during 

 August. The sperm whales were approximately 222 km offshore, close to the 1,000-m 

 contour (Map 13). 



During November one group of bottlenose dolphins, located in proximity to an 

 unidentified small whale, was encountered beyond the 200-m contour (Map 16). However, 

 71% of all bottlenose dolphin sightings in November were within the 50-m contour. The 

 only sighting of unidentified dolphins during November was in water beyond the 200-m 

 contour (Map 16). 



43 



