FISHERY BULLETIN: VOL. 78, NO. 3 



Figure 3. — Distribution of sightings of three bottlenose dolphins (Thick Fin, Raggedy Ann, and Teaser) near Port Aransas, Texas, 

 during 1976-77 . The map is a diagram (not drawn to scale) of the study area shown in Figure 1, and the circled numbers identify the same 

 seven sections of the study area given in Figure 1. 



Table 4. — Sightings of individual bottlenose dolphins in in- 

 shore waters near Port Aransas, Texas. Only dolphins sighted 25 

 or more times from June 1976 through May 1977 are included. 

 Region A includes Aransas Pass (1), the Confluence (2), Lydia 

 Ann Channel (3), and Corpus Christi Channel (6) (total area, 11 

 km^). Region B includes Morris and Cummings Cut (5) (total 

 area, 14 km^). 



the northeast boundary where Lydia Ann Chan- 

 nel joins Aransas Bay. 



DISCUSSION 



Seasonal Occurrence 



Contrary to Gunter (1942), the present study 

 provides evidence for seasonal variation in abun- 

 dance of T. truncatus in Texas. As Figure 2 shows, 

 the winter population in the study area was about 

 twice the size of the summer population. The popu- 

 lation increased or declined during the fall and 

 spring as dolphins moved into or out of the study 

 area. Irvine et al. (footnote 3) noted fewer dolphins 

 in their study area in central west Florida during 

 the winter than during the summer. They also 

 observed seasonal changes in the distribution of 

 bottlenose dolphins in that area. Seasonal migra- 

 tions have been hypothesized for T. truncatus on 

 the Atlantic coast (True 1890), and Caldwell and 

 Caldwell (1972) noted variations in abundance of 



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