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Fishery Bulletin 102(4) 



mately 40 |im (nucleus, 40-80 Jim, 80-120 ^m, 120-160 

 urn, and 160-200 fim) across the otolith, to a distance 

 of 200 ^m from the nucleus. 



Results 



Electron probe microanalysis 



A total of six elements (Na, P, S, CI, K, and Sr) were 

 quantified in the otoliths of pollock larvae by using 

 EPMA. Average concentrations of the elements ranged 

 from approximately 4 mg/g (otolith weight) for Na to 

 less than 1 mg/g for CI, S, and K. We found significant 

 differences in the elemental composition both among 

 sampling locations and across positions on the oto- 

 liths. Multivariate analyses of elemental signatures 

 revealed significant differences among locations from 

 samples 0-20 urn from the nucleus (M ANOVA; Pillai's 

 trace=1.18; F 30 , 560 =5.74; P<0.0001), and 20-45 fim from 



the nucleus (MANOVA; Pillai's trace = 1.47; F., 



, = S,Sli; 



P<0.0001l. 



Analysis of variance and Tukey's HSD a posteriori 

 multiple comparison tests identified the individual ele- 

 ments contributing to differences in the multivariate 

 signatures among locations. All six elements showed 

 significant differences among locations at 0-20 /tm from 

 the otolith nucleus (Table 3). Multiple comparisons for 

 each of the elements indicated relatively subtle differ- 

 ences among locations. Phosphorus concentrations were, 

 however, significantly higher in samples from Yakutat 

 than any of the other locations. Results of the ANOVA 

 from samples at distances 20-45 j<m from the nucleus 

 were generally comparable with samples closer to the 

 nucleus (Table 3). Although only CI showed no signifi- 

 cant variation among locations (Table 3), multiple com- 

 parisons of mean values for each element revealed little 

 geographic patterns among locations. Note that Shelikof 

 Strait samples were removed from this analysis because 

 of a small sample size in this distance category. 



