NOTE Giorgi et al.: Migratory characteristics of juvenile Oncorhynchus tshawytscha 



879 



The variability in travel-time estimates observed 

 in this study may in part have resulted from limited 

 sampling capability at John Day Dam, since only 0.3 

 to 1.3% of any marked group was recovered at that 

 site. There were four groups from which less than 10 

 recaptures were observed (Tables 1 and 2). However, 

 the travel-time estimates of Berggren and Filardo 

 ( 1993) displayed generally the same range of values, 

 even though sampling effort at John Day Dam was 

 increased during the latter years on which their 

 analyses were based. 



Another confounding factor is that our investiga- 

 tion treated the entire composite population of zero- 

 age juveniles. For future studies, we suggest study- 

 ing individual stocks of fish to describe any unique 

 migratory characteristics that may be stock-specific. 



Acknowledgments 



We are grateful to Carl Sims and Dennis Umphries 

 who participated in various phases of the study. John 

 Williams and Kurt Gores reviewed the manuscript 

 and provided useful comments. This research was 

 supported in part by the Department of Energy and 

 the Bonneville Power Administration. 



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