Present address: Cramer Fish Sciences, 13300 New Airport Road, Suite 102, Auburn, CA 95602, USA.
Juvenile Chinook salmon, Oncorhynchus tshawytscha, growth and diet in riverine habitat engineered to improve conditions for spawning
Version of Record online: 14 MAY 2012
© 2012 Blackwell Publishing Ltd
Fisheries Management and Ecology
Volume 19, Issue 5, pages 375–388, October 2012
How to Cite
Utz, R. M., Zeug, S. C. and Cardinale, B. J. (2012), Juvenile Chinook salmon, Oncorhynchus tshawytscha, growth and diet in riverine habitat engineered to improve conditions for spawning. Fisheries Management and Ecology, 19: 375–388. doi: 10.1111/j.1365-2400.2012.00849.x
- Issue online: 12 SEP 2012
- Version of Record online: 14 MAY 2012
- habitat restoration;
- Chinook salmon (Oncorhynchus tshawytscha);
- Merced River;
- food web;
Abstract Many habitat enhancement techniques aimed at restoring salmonid populations have not been comprehensively assessed. The growth and diet of juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), rearing in a reach designed to enhance spawning were evaluated to determine how a non-target life stage fared in the engineered habitat. Prior work demonstrated differences in food web structure between restored and unenhanced reaches of the Merced River, thus juvenile salmon feeding dynamics were also hypothesised to vary. Dependent variables were compared among fish collected from within and near the upper boundary of the restored reach and in an unenhanced habitat upstream. Diets, otolith-derived growth and stable isotope-inferred trophic positions were compared. Baetidae mayflies were particularly important prey in the restored reach, while elsewhere individuals exhibited heterogeneous diets. Salmon residing at the bottom of the restored reach exhibited slightly faster growth rates relative to fish collected elsewhere, although stable isotope and diet analyses suggested that they fed at a relatively low trophic position. Specialised Baetis predation and/or abundant interstitial refugia potentially improved rearing conditions in the restored reach. Data suggest that gravel enhancement and channel realignment designed to augment adult spawning habitat may simultaneously support juvenile Chinook salmon despite low invertebrate food resources.