|Document Type:||Journal Article|
|Title:||Residence times of juvenile salmon and steelhead in off-channel tidal freshwater habitats, Columbia River, USA|
|Author:||G. E. Johnson, G. R. Ploskey, N. K. Sather, David J. Teel|
|Journal:||Canadian Journal of Fisheries and Aquatic Sciences|
|Keywords:||residency,juvenile salmon,tidal freshwater,residence time,juvenile salmon,life history,tidal freshwater|
We documented two life history strategies for juvenile salmonids as expressed in off-channel tidal freshwater habitats of the Columbia River: 1) active migrations by upper river Chinook salmon and steelhead during the primary spring and summer migration periods, and 2) overwinter rearing in tidal freshwater habitats by coho salmon and naturally produced Chinook salmon mostly from lower river sources. During spring/summer 2007-2008, acoustic-tagged fish originating above Bonneville Dam (rkm 234) had short residence times in off-channel areas (rkm 192-203): median 2.5 and 2.6 h for yearling (mean lengths 134 and 158 mm) and 3.0 and 3.4 h for subyearling (104 and 116 mm) Chinook salmon, and 2.5 h for yearling steelhead (215 mm). The percentage of fish in off-channel areas out of the total in the main- and off-channels areas was highest for yearling Chinook salmon (8.1 and 9.3% for 2007 and 2008, respectively), and lowest for steelhead (4.0% for 2008) and subyearling Chinook salmon (3.6 and 6.1% for 2007 and 2008, respectively). In late January and early February 2010, 2011, and 2012, we captured and tagged yearling Chinook and coho salmon occupying off-channel tidal freshwater habitats. Median residence times in off-channel areas were 11.6-25.5 d for juvenile Chinook (106, 115, and 118 mm, respectively by year) and 11.2 d for coho salmon (116 mm). This study is the first to estimate residence times for juvenile salmonids specifically in off-channel areas of tidal freshwater and, most importantly, residence times for Chinook salmon expressing a life history of overwintering in tidal freshwater. The findings support restoration of shallow off-channel habitats in tidal freshwater portions of the Columbia River.
|Theme:||Recovery and rebuilding of marine and coastal species|
Develop methods to use physiological, biological and behavioral information to predict population-level processes.