238 



Fishery Bulletin 97(2), 1999 



Discussion 



Hapuku otoliths frequently had split opaque bands 

 and were difficult to age. This led to reduced count- 

 ing precision and, for some age groups, to a small 

 between- and within-reader ageing bias. Our use of 

 marginal increment analysis to validate hapuku 

 otolith ageing was inconclusive. We attribute this to 



the compound nature of the opaque bands and to the 

 resulting difficulty in determining whether the ma- 

 terial being deposited at the margin was opaque or 

 hyaline. 



The results of the OTC injection experiment were 

 consistent with the deposition of one opaque and one 

 hyaline band per year. This does not constitute full 

 validation of the otolith ageing technique because the 



