Page 

 CONTENTS 



Introduction 1 



Materials and methods 1 



Results of analyses 2 



Sample size 2 



Vertebral abnormalities 2 



Variation between sexes 2 



Variation with length 2 



Variation among samples and localities 3 



Variation within groups 5 



Variation between year classes 6 



Discussion 6 



Summary 7 



Literature cited 8 



Appendix H 



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