Wintner and Cliff; Age and growth] determination of Carcharodon carcharias 



157 



Table 3 



Percentage agreement in paired growth ring (GR) counts 

 between methods. Numbers in parentheses indicate sample 



Difference between counts 



Methods 



OGR 



1 GR 2 GR 3 GR 



SC-A- 

 SC-A- 



SC-B 

 XR-A 



42.5(45) 

 59.6(65) 



41.5(44) 

 34.9(38) 



15.1(16) 



4.6(5) 



0.9 

 0.9 



106 

 109 



taken as a GR estimate in all three methods and used 

 for all further calculations. The two readers agreed 

 on the mean GR estimate in 42.59c of the vertebrae; 

 in 59. 6% of the vertebrae there was no difference 

 between GR estimates obtained by the same reader 

 using the two methods (Table 3). 



Centrum analyses 



Prebirth marks were found in all vertebrae with 

 method XR-A and in 33% of the vertebrae with 

 method SC-A (Table 4). Using all three methods, we 



Table 4 



Percentage of vertebrae where prebirth marks were present 

 and nature of the first band after the angle change. 



Method 



SC-A 

 SC-B 

 XR-A 



Prebirth 

 marks 



First band after angle change 



opaque 



translucent 



% 



33 



100 



114 



114 



94 

 96 



6 



4 

 12 



62 



97 

 81 



