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Fishery Bulletin 92(2), 1994 



backbones were oven-dried at 

 70°C overnight, ground to a pow- 

 der, and a 0.01 g subsample from 

 each fish was used for analysis 

 (Ennevor, 1991; Ennevor and 

 Beames, 1993). The prepared 

 samples were submitted to a com- 

 mercial laboratory in North 

 Vancouver, British Columbia for 

 ICP-MS analyses. 



Experiments 1 and 2 were ana- 

 lyzed by analysis of variance with 

 SYSTAT statistical software 

 (Wilkinson, 1989) and differences 

 between means were tested at 

 P<0.05 with Tukey's multiple 

 range test. The data were pooled 

 by treatment groups with indi- 

 vidual fish as experimental units. 



Results 



Experiment 1 



Lanthanum and cerium adminis- 

 tered at 50 ug-L" 1 daily for 24 days 

 had no apparent deleterious effect 

 on the fry. They appeared to be 

 healthy and fry weights between 

 treated and non-treated groups 

 did not differ after the 24-day treatments and 14- 

 day rinse were completed. Few mortalities occurred 

 in all groups (Table 1). 



Analysis of the vertebral columns from the marked 

 fry showed each of the lanthanides to be present in 

 approximately equal amounts. Uptake did not differ 

 between the treatment groups. The average concen- 

 tration of lanthanide in the vertebral columns was 

 6.1 ng of lanthanum or 6.2 ng of cerium (Table 1). 



Experiment 2 



Throughout the treatments, mortalities were higher 

 in tanks that contained the 150 ug-L" 1 treatments of 

 lanthanum or cerium (Table 1). Fewer mortalities 

 were observed in the 100 ug-L -1 treatments; none in 

 the 50 ug-L" 1 treatments. However, after the 24-day 

 treatment period and 14-day rinse period were com- 

 pleted, fry weights did not differ between groups 

 treated with lanthanum or cerium and nontreated 

 groups (Table 1). 



Results of the analyses of the vertebral columns 

 from the marked fry showed a trend of significantly 

 (P<0.05) decreased uptake of lanthanum and cerium 

 with decreased exposure time regardless of concen- 



Table 1 



Percent mortalities during the 24-day treatment period, mean body weights 

 of coho salmon, Oncorhynchus kisutch, fry at time of sampling, mean 

 amounts (ng) ± 1 S.E.M. of lanthanum or cerium in vertebral columns of 

 fry marked in Experiments 1 and 2. Within experiments, mean values shar- 

 ing a similar superscript letter were not significantly different (P<0.05) 

 according to Tukey's Test. 



1 La* or Ce* represents the chloride forms, LaCl 3 or CeCl 3 , respectively; all other treatments 

 used the acetate forms of La(C 2 H 3 2 > 3 or Ce(C 2 H 3 2 ) 3 . 



2 Mean weights of treatment groups after 24-day treatment period and 14-day rinse period 

 completed. 



tration (Table 1). Groups treated with lanthanum or 

 cerium at 50 ug-L" 1 daily had the greatest accumu- 

 lation, whereas the groups treated with 150 ug-L" 1 

 every third day had the least. In the groups treated 

 with either element, lanthanum and cerium were 

 accumulated in approximately equal amounts. 



Discussion 



Coho salmon fry were successfully marked with lan- 

 thanum or cerium that was administered through 

 the water supply. The lanthanides were detected in 

 the vertebral columns of marked fry, which is con- 

 sistent with previous findings (Ennevor, 1991; 

 Ennevor and Beames, 1993) and with the bone-seek- 

 ing characteristics of the lanthanide elements 

 (Durbin et al., 1956; Jowsey et al., 1958). Ennevor 

 and Beames ( 1993) have shown that lanthanides that 

 are deposited in the vertebral column, otoliths, and 

 scales remain in these tissues for at least 10.5 months 

 after marking. Michibata (1981) also successfully 

 marked medaka, Oryzias latipes, and goldfish, Caras- 

 sius auratus, with samarium, another lanthanide, 

 and these fishes retained detectable amounts of the 

 element in their scales one year after marking. 



