NOTE Fey et al.: Effect of type of otolith and preparation technique on age estimation of Leiostomus xanthurus 



551 



that increments in lapilli of Barbus sclateri (Pisces: Cy- 

 prinidae) were more clearly defined than in sagittae and 

 asterisci. Similarly, our results demonstrate the utility 

 of lapilli for larval and juvenile fish age estimates. 



In addition to the choice of the most suitable type of 

 otolith, the choice of the most appropriate preparation 

 method is an important aspect of larval and juvenile 

 fish age determination (Secor et al., 1992). Analysis 

 of PIS whole sagittae provided in the current study 

 similar precision and confidence in age determination 

 as transverse sections. Although analysis of sagittal 

 transverse sections have been applied to spot ( Siegfried 

 and Weinstein, 1989), the most frequently used method 

 has been the analysis of whole sagittae in sagittal view 

 (Hettler, 1984; Warlen and Chester, 1985; Powell et al., 

 1990; Flores-Coto and Warlen. 1993; Ross, 2003). Re- 

 cently, Ross (2003) was able to age 40-160 day-old spot 

 juveniles, analyzing whole sagittae along the sagittal 

 view; however, polishing on both sides was frequently 

 necessary. For whole lapilli, however, only one prepara- 

 tion method (i.e., polishing along the sagittal plane) was 

 used in the present study and the results were more 

 satisfactory then those obtained for sagittae and hence 

 no other preparation method (i.e., sectioning) seemed 

 to be required. 



In conclusion, first-increment formation occurs at 

 hatching in the sagittae and at 6-7 days after hatching 

 in the lapilli. Increment formation rate occurs daily in 

 both the sagittae and the lapilli. With sagittal and lapil- 

 lar increment counts, age was underestimated and the 

 cause appeared to be difficulty in discerning increments 

 near the core. Whole lapilli (prepared by polishing one 

 side along the sagittal section) provided age accuracy 

 similar to that of the three sagittal preparations, but 

 higher precision. Future studies would benefit from us- 

 ing the lapillus for ecological studies of the early life 

 history of spot. 



Acknowledgments 



The authors thank Elisabeth Laban for consultation 

 during otolith preparation and analysis, as well as Dean 

 Ahrenholz and Jennifer Potts for reviewing the earlier 

 version of the manuscript. This research was performed 

 while the first author held a National Research Council 

 Research Associateship Award at the NOAA Beaufort 

 Laboratory. 



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