Gillanders et al : Aging methods for Seriola lalandi 



825 



320 410 



T*"" ! 1 1 



500 590 680 770 860 950 1.040 



320 410 500 590 680 770 860 950 1,040 



Size class (mm) 



Figure 8 



Observed length-frequency distributions for kingfish data (sliaded histograms), showing the fit 

 of the MULTIFAN model (see Table 5 for model details). Estimated frequencies for each age 

 class (inner smoothed curves) and for the sum of all age classes (outer smooth curve) are shown. 

 Vertical lines represent the estimated mean lengths-at-age in each sample. 



1979; Campana. 1984). Manooch and Potts (1997) 

 have used sectioned otoliths to age S. dumerili but 

 commented that age and growth determinations were 

 very difficult. Measurements could only be made on 

 48% of samples and zones could only be counted on 

 71% of samples and thus may have biased estimates 

 of growth in their study. Whole otoliths were examined 

 in their study solely to determine the plane of section- 

 ing (Manooch and Potts, 1997). Because whole oto- 



liths may imderestimate age of large fish (e.g. Beamish, 

 1979; Campana, 1984), it may also be useful to look 

 at transverse sections of otoliths of kingfish for ex- 

 tremely large fish (>20 kg). 



Comparison of age- and length-based data 



Although not strictly comparable (see Francis, 1988a, 

 1995), estimates of growth from length-frequency, 



