FISHERY BULLETIN: VOL. 78, NO. 3 



Figure l. — Bottlenose dolphin study area near Port Aransas, Texas. Circled numbers designate the seven sections of the study area: 

 1) Aransas Pass, 2) the Confluence, 3) Lydia Ann Channel, 4) Corpus Christi Bayou, 5) Morris and Cummings Cut, 6) Corpus Christi 

 Channel, and 7) Aransas Channel. The boundaries of the study area are the ends of the jetties at the southeast end of section 1, the 

 mouth of Aransas Bay to the northeast, the mouth of Corpus Christi Bay to the southwest, and the islands along the northwest border of 

 sections 4 and 5. The zigzag line drawn through section 3 shows the path followed while conducting zigzag censuses of dolphins. Similar 

 paths were followed while censusing dolphins in the other sections. 



boat at slow speed back and forth through a sec- 

 tion and counting all dolphins sighted (Figure 1). 

 A total of 335 zigzag censuses was conducted dur- 

 ing 201 h during the 1-yr study. The average time 

 per census was 23.9 min for Aransas Pass, 11.0 min 

 for the Confluence, 55.7 min for Lydia Ann Chan- 

 nel, 28.3 min for Corpus Christi Bayou, 63.5 min 

 for Morris and Cummings Cut, 52.6 min for Cor- 

 pus Christi Channel, and 25.6 min for Aransas 

 Channel. 



Data on direction of dolphin movement, tidal 

 state, and time of day were used to identify daily 

 movement patterns. The terms used to describe 



direction of movement in sections 1, 3, and 6 are 

 "up" for movement toward the bays and "down" for 

 movement toward the Gulf of Mexico. Time of day 

 is divided into three periods: early (0700-0900 h), 

 midday (1000-1300 h), and late (1400-1900 h). Very 

 few observations were made from 2000 to 0600 h, 

 so this time period is not considered. The chi- 

 square test was used to determine whether there 

 was a significant relationship between dolphin 

 movements and tide and time of day. When a rela- 

 tionship was found to be significant (P<0.01), the 

 strength of the relationship was measured by 

 Cramer's V (Nie et al. 1970). 



594 



