Rocky Mountain Research Station Publications

RMRS Online Publication - Journal Articles, External Publications, and Special Reports
Influences of body size and environmental factors on autumn downstream migration of bull trout in the Boise River, Idaho


Monnot, Lauri; Dunham, Jason B.; Hoem, Tammy; Koetsier, Peter. 2008. Influences of body size and environmental factors on autumn downstream migration of bull trout in the Boise River, Idaho. North American Journal of Fisheries Management. 28: 231-240.

Many fishes migrate extensively through stream networks, yet patterns are commonly described only in terms of the origin and destination of migration (e.g., between natal and feeding habitats). To better understand patterns of migration in bull trout, Salvelinus confluentus we studied the influences of body size (total length [TL]) and environmental factors (stream temperature and discharge) on migrations in the Boise River basin, Idaho. During the autumns of 2001-2003, we tracked the downstream migrations of 174 radio-tagged bull trout ranging in size from 21 to 73 cm TL. The results indicated that large bull trout (.30 cm) were more likely than small fish to migrate rapidly downstream after spawning in headwater streams in early autumn. Large bull trout also had a higher probability of arriving at the current terminus of migration in the system, Arrowrock Reservoir. The rate of migration by small bull trout was more variable and individuals were less likely to move into Arrowrock Reservoir. The rate of downstream migration by all fish was slower when stream discharge was greater. Temperature was not associated with the rate of migration. These findings indicate that fish size and environmentally related changes in behavior have important influences on patterns of migration. In a broader context, these results and other recent work suggest, at least in some cases, that commonly used classifications of migratory behavior may not accurately reflect the full range of behaviors and variability among individuals (or life stages) and environmental conditions.

Keywords: bull trout, Salvelinus confluentus, Boise River, Idaho, migration


About PDFs: For best results, do not open the PDF in your Web browser. Right-click on the PDF link to download the PDF file directly to your computer. Click here for more PDF help.


Download Article
http://www.fs.fed.us/rm/pubs_other/rmrs_2008_monnot_l001.pdf

PDF File Size: 205 K


Title: RMRS Other Publications: Influences of body size and environmental factors on autumn downstream migration of bull trout in the Boise River, Idaho
Electronic Publish Date: September 25, 2008
Last Update:
September 25, 2008

RMRS Publications | Order a publication | Contact Us