Juvenile Oncorhynchus mykiss migrate extensively in freshwater during the fall. We used individual tagging to study the spatial origin, influences, and outcomes of fall migration on fish that emigrated from summer rearing tributaries during the fall (early emigrants) and those that did not (late emigrants) in the South Fork John Day River, Oregon. Fall migration amplified body size differences between early and late emigrants. There were more early emigrants from a lower-gradient stream than from a higher-gradient stream. Early emigration was positively related to individual summer growth rate and fall body size. Oncorhynchus mykiss dispersed downstream into higherorder streams during the fall. Early emigrants shifted to an alternative location and experienced significantly greater winter growth than did late emigrants that remained in tributaries. Early emigrants initiated smolt migration sooner the following spring than did late emigrants. Early and late emigration from the South Fork John Day River was associated with asynchronous emigrant-to-adult survival rates.

I. A. Tattam et al.
Short Description: 
This project studied size and growth rates on population-scale and individual-scale migration of salmon in the South Fork of the John Day River, Oregon.
Product Number: 
Entry Date: 
Friday, May 9, 2014
9 pp.
Size and Format: 
8 1/2 x 11, online
Source (Journal Article): 
Transactions of the American Fisheries Society
DOI Number (Journal Article): 
Year of Publication: