NOTE Fenton and Short: Radiometric analysis of Macruronus novaezelandiae otolith cores 



393 



Results 



Otolith core dimensions 



Otolith growth in linear dimensions and weight for 

 juvenile blue grenadier (0+, 1+, 2+, and 3+) was rapid 

 (Table 1). The cores that were removed approximated 

 the linear dimensions of 1+ fish, but they were 

 heavier than the average 1+ fish with a weight that 

 was not significantly different from that of 2+ fish ( 

 £=1.15;P>0.20). The dimensions and weight of 3+ fish 

 otoliths were significantly greater than the isolated 

 core dimensions. Therefore, in view of the core weight 

 our calculation of age assumed that the cores ana- 

 lyzed represented 2 years of growth. 



Stable element analysis 



Low levels of both stable lead and barium were found 

 in all the samples (Table 2). Stable lead ranged from 

 0.269 to 1.78 ppm. Barium levels were low, ranging 

 from 1.50 to 2.28 ppm, consistent with the relatively 

 low 226 Ra levels in these blue grenadier otolith cores. 

 The ratio of Pb/Ba was relatively high, ranging from 

 0.17 to 0.78. From this Pb/Ba data we concluded that 



there is some allogenic uptake of 210 Pb from the en- 

 vironment. However the extent of uptake was diffi- 

 cult to assess given the low levels of Pb and Ba mea- 

 sured. The Sr/Ca ratio ranged between 0.0034 and 

 0.0042. 



Radiometric results 



210 Pb ranged from 0.0040 ±0.0045 to 0.0078 ±0.0025 

 dpm-g- 1 (Table 3). The 226 Ra content of the otolith 



Table 2 



Blue grenadier, Macruronus novaezelandiae, stable element 

 data from inductively coupled plasma mass spectrometry 

 (ICP-MS) and inductively coupled plasma atomic emission 

 spectrometry (ICP-AES) analysis of otolith core solutions. 



Sample Pb Ba Pb/Ba Sr Ca Sr/Ca 

 number ppm ppm ppm/ppm ppm ppm ppm/ppm 



LH 2269 0.749 1.50 0.50 



LH 2270 1.78 2.28 0.78 



LH2271 0.389 1.57 0.22 



LH2272 0.269 1.55 0.17 



1590 400300 0.0040 

 1620 387800 0.0042 

 1810 448380 0.0040 

 1920 483570 0.0040 



