610 



Fishery Bulletin 102(4) 



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Distance from nucleus (mm) 



Figure 4 



Profiles of elemental concentrations, determined by electron probe 

 microanalysis, from the nucleus out to a distance of approximately 

 90 Jim in the otoliths of larval walleye pollock iTheragra chal- 

 cogramma) collected from the North Bering Sea (A), southeast 

 Bering Sea (O), Bristol Bay (■), Prince William Sound (O), and 

 Yakutat ("I. Individual points are mean ( + SE) values grouped 

 at 15-f/m intervals. 



five elements (Sr, K, S, P, and Na). Finally, the interac- 

 tion term (positionxlocation) in the repeated measures 

 ANOVA tested the hypothesis that the shape of the 

 elemental profiles differed among locations. There was 

 a significant interaction between profile and location 

 for K. 



Laser ablation ICP-MS 



We quantified Mn/Ca, Sr/Ca, and Ba/Ca ratios in the 

 otoliths of larval walleye pollock using laser ablation 

 ICP-MS. Both Mn and Ba were found at trace levels in 

 otoliths, with average values of approximately 3 jimo}/ 

 mol and 6 umol/mol, respectively. Strontium was present 

 in the otoliths at an average concentration of approxi- 

 mately 2.2 mmol/mol. A MANOVA detected significant 

 differences among locations from a raster centered on 

 the nucleus (MANOVA; Pillai's trace = 0.85; F lz99 =3.26; 

 P<0.0005), and from the average values of lines 40-80 

 pm from the nucleus (MANOVA; Pillai's trace = 0.99; 

 F 1299 =4.1;P<0.0001). 



Univariate ANOVA and a posteriori multiple compari- 

 sons by using Tukey's HSD revealed that Mn/Ca, Sr/Ca, 



-4-2024 



deamahcei eenhe(Jg 



Figure 5 



Plot of the first two canonical 

 variates contrasting multivari- 

 ate elemental signatures in oto- 

 liths of walleye pollock iTheragra 

 chalcogramma) determined with 

 laser ablation ICP-MS, at 0-40 fan 

 from the nucleus (A) and 40-80 

 fim from the nucleus (Bi. Larvae 

 and juveniles were collected from 

 the North Bering Sea (At, south- 

 east Bering Sea (O). Bristol Bay 

  Prince William Sound (♦), and 

 Yakutat ( I. 



and Ba/Ca ratios varied significantly among locations 

 at the otolith nucleus and at positions 40-80 um from 

 the nucleus (Table 5). Samples from the North Bering 

 Sea had consistently lower Sr/Ca and Ba/Ca ratios than 

 those from the southeast Bering Sea at both positions. 

 However, we noted only subtle differences among the 

 Gulf of Alaska and Bristol Bay samples. 



We found a total of three groupings in canonical plots 

 of multivariate elemental signatures from the otoliths of 

 larval walleye pollock (Fig. 5). Samples from the North 

 Bering Sea and Bristol Bay were separated along ca- 

 nonical variate one. A third grouping, including larvae 

 from the southeast Bering Sea, Prince William Sound, 

 and Yakutat, clustered together in the center of the 

 canonical plot. Samples from the nucleus and 40-80 

 fim outside the nucleus showed very similar geographic 

 patterns. 



Repeated measures ANOVA detected significant dif- 

 ferences in both Mn/Ca and Ba/Ca profiles from the nu- 



