908 



Fishery Bulletin 97(4), 1999 



20 

 30 

 40 

 50 

 60 

 70 

 80 

 90 

 100 



B10 B11 B04 BOS 



826 



■12 

 703 



-37 

 78S 



-45 

 -28 

 -23 

 589 



BIO 

 B11 

 B04 

 BOS 



ABlOg 



ABOSd 



AB04C^ 



AB11C5 



Figure 4 



Top: dendrogram illustrating intrapod groups and 

 relationships among individuals with CAI values 

 calculated at the population level. (Relationships 

 among intrapod groups shown in Fig. 12.) Middle: 

 matrix showing CAI values between pairs of indi- 

 viduals calculated at the pod level for AB pod, ABIO 

 subpod. Numbers at the base of each column in the 

 matrix are the number of valid photo sequences in 

 which that individual appears. Bottom: inferred ge- 

 nealogical trees. 



could be deduced by examination of bond strengths 

 within these groups. CAI values were calculated be- 

 tween all individuals of each pod and dendrograms 

 of the CAI values were constructed to reveal the 

 structure of associations between the members of 

 each pod (Figs. 1, and 3-12). 



The individuals in the nine pods examined in the 

 second CAI analysis were placed in 39 postulated 



maternal genealogical trees on the basis of linkages 

 established in association analysis. An additional four 

 newborn calves were observed in 1996 and placed in 

 the genealogical trees on the basis of field observa- 

 tions only. Genealogical trees were constructed by 

 first establishing all known mother-offspring rela- 

 tionships from field observations. There were 58 off- 

 spring born during the study that appeared in the 

 photographs used for association analysis. In all but 

 one case (AB41 and mother AB8), the CAI values be- 

 tween offspring and their known mothers was higher 

 than for any other pairings of individuals. Direct ob- 

 servation also indicated that offspring maintained their 

 strongest bonds with their known mothers throughout 

 the study period. The three offspring born at the be- 

 ginning of the study were still most strongly bonded to 

 their mothers after 12 years. These were mother-off- 

 spring pairs AI3 and AI4 (CAI=27); AK6 and AK8 

 ( CAI=34 ); and AE 1 1 and AE 13 ( CAI=46 ), 



The strength of the bond between females and their 

 mothers declined in the nine cases in which females 

 became reproductive during the study and their 

 mothers remained alive throughout the study (Table 

 3), A paired t test of CAI values for 1984-88 and CAI 

 values for 1989-95 showed that the tendency for as- 

 sociations to decline after female offspring become 

 reproductive was statistically significant (^=4,88, 

 P=0.0012). 



There were 31 juveniles (estimated age 10 years 

 or less in 1984) at the beginning of the study. Asso- 

 ciation analysis indicated that all but five of these 

 whales remained most closely bonded to the whales 

 judged by direct observation to be their mothers. 

 Three of these exceptions were females that produced 

 calves (AK7 and calf AK12: AN8 and calves AN41 



