Fiedler and Reilly: Interannual variability of dolphin habitats and abundances 



455 



Axis Score 



- Spotted Dolphin 

 Common Dolphin 



- Eastern Spinner Dolphin 



- Whitebelly Spinner Dolphin 



- Striped Dolphin 



Figure 2 



CCA-derived Gaussian distributions of dolphin species habitat qual- 

 ity, H (from MOPS 1986-90 encounter rates), along the first two 

 canonical axes. The values are scaled so that the mean of H tj is 1.0 

 over a range of ±2 units (standard deviations) on the canonical axis. 

 Spotted dolphin = Stenella attenuata, common dolphin = Delphinus 

 delphis, eastern spinner dolphin = S. longirostris orientalis, 

 whitebelly spinner dolphin = S. longirostris, striped dolphin = S. 

 coeruleoalba. 



Spotted dolphin habitat was centered south and 

 southwest of the southern coast of Mexico to about 

 3°N (Fig. 3). This corresponds to the warm, tropical 

 surface water mass of Wyrtki ( 1966, see Fig. 1 in 

 Reilly and Fiedler, 1994). The Costa Rica Dome 

 (10°N, 90°W) was a notable gap in favorable spot- 

 ted dolphin habitat. 



Eastern spinner dolphins were even more closely 

 associated with warm tropical surface water. High- 

 est values of H for this stock were found off south- 

 ern Mexico, in the center of the "coastal tropical" 

 habitat defined by canonical axis 1 (Reilly and 

 Fiedler, 1994). Whitebelly spinner dolphins were as- 

 sociated with subtropical surface water (Wyrtki, 

 1966) to the northwest and southwest of the tropi- 

 cal surface water in the core of the MOPS area. 



Table 4 



Dolphin species scores (standardized) ±tolerances 

 on the first two canonical axes from canonical 

 correspondence analysis (CCA). Dolphin species: 

 spotted = Stenella attenuata, common = Delphi- 

 nus delphis, eastern spinner = S. longirostris 

 orientalis, whitebelly spinner = S. longirostris, 

 striped = S. coeruleoalba. 



AX1 



AX2 



Spotted 

 Common 

 Eastern spinner 

 Whitebelly spinner 

 Striped 



-0.53 ± 0.57 



1.68 ± 1.16 



-0.84 ± 0.49 



-0.37 ± 0.55 



0.24 ± 0.69 



0.19 ± 0.54 



0.28 ± 0.48 



0.86 ± 0.71 



-1.51 ± 1.19 



-0.08 ± 0.55 



