Restoring Anadromy: Identifying historic fish passage beyond natural obstacles in
the Oregon Cascades
Sierra Lewis1, Jennifer McKay2, David Noakes1,3
(1) S. Lewis (presenter): Oregon State University, Department of Fisheries and Wildlife,
Corvallis, OR, Sierra.lewis@oregonstate.edu
(2) Oregon State University, College of Earth, Ocean and Atmospheric Science
(3) Oregon Hatchery Research Center
Historically, fish passage research has focused on mitigation of impacts due to man-made
barriers, and project success is defined as observed passage beyond these obstacles to
reconnect fragmented habitats. Restoring aquatic connectivity for migratory fishes in the
headwaters of rivers can be an expensive restoration proposition if the total length of
stream or river to be regained is uncertain due to natural barriers. We collected telemetry
data on non-marked, migratory steelhead, O. mykiss, which were transplanted above a
known hydropower barrier. We documented observed behaviors such as habitat
exploration, holding, spawning, and outmigration timing from June 2010 to June 2011. We
also collected and analyzed foliar samples from Douglas fir trees, P. menziesii, (>100 years
old) to determine 15N nutrient linkages between headwater tributaries of the main-stem
river in an effort to discern the true extent of historic anadromy above both a hydropower
dam as well as a natural waterfall complex in the last major tributary below the end of
historic anadromy. By comparing the telemetry data with the potential historic
distribution, as elucidated by marine nutrient deposition patterns throughout the
headwater tributaries of this coastal river, we hope to improve the methodology used to
define project success through restorative alteration of anthropogenic barriers. This poster
displays the initial results which seem to be confounded with elevation and the presence of
nitrogen-fixing species, such as red alder (A. rubra).