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Winter ecology of juvenile coho salmon (Oncorhynchus kisutch) in modified and unmodified sections of a coastal stream

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Title Winter ecology of juvenile coho salmon (Oncorhynchus kisutch) in modified and unmodified sections of a coastal stream
Names Phillips, Stephen H. (Stephen Homes), 1957- (creator)
Tubb, Richard A. (advisor)
Date Issued 1986-05-28 (iso8601)
Note Graduation date: 1987
Abstract Natural and gabion modified habitats containing coho salmon
(Oncorhynchus kisutch) were observed and measured seasonally in East
Fork Lobster Creek, a fifth order stream in western Oregon. Coho
salmon usually inhabited backwater and secondary channel pools in
winter. Large wood debris complexes and undercut banks were the
primary sources of cover in winter. Beaver activity played a vital
role in creating summer and winter habitat.
Discharge rates seemed to have more influence than temperature in
regulating coho winter hiding behavior. Lower than usual stream
discharges of the 1984-85 winter allowed many fish to move out from
cover, and a large portion of the coho were found more than 2 meters
from cover. Coho were also not as dependent on cover during the low
flows of spring and summer, and these low discharges allowed fish to
inhabit less complex sites.
Study sites with gabions maintained large numbers of fry
throughout the spring and summer. Fish were attracted to the gabion-created
plunge pools in low stream discharge months but not in high
discharge months. During winter high discharges, gabion sites with
backwater pool habitat held relatively larger numbers of fish than
gabion sites without such habitat.
Genre Thesis/Dissertation
Topic Coho salmon -- Habitat
Identifier http://hdl.handle.net/1957/40191

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