Abstract: Tributary Rearing Salmon 97
Intermittent Streams as Rearing Habitat for Sacramento River Chinook Salmon: 1997 Update
Paul E. Maslin
Mike Lennox
Jason Kindopp
and
William R. McKinney
Abstract
The investigation of nonnatal rearing of juvenile chinook salmon (Oncorhynchus tshawytscha) in intermittent tributaries to the Sacramento River was continued another season. This year the work was expanded to include 24 small tributaries of the Sacramento River. Streams with a near-mouth gradient of less than 1% contained juvenile chinook although there was a great deal of variation in number present and distance they moved upstream. Densities were usually low, but ranged up to nearly 6 juveniles per linear meter, with the greatest numbers present between mid-February and mid-April. Tributary-rearing chinook were in good condition and grew rapidly. Individuals of the correct size to be members of each of the four Sacramento chinook races were observed but rapid tributary growth makes race assignments based on size questionable. With a few exceptions, the intermittent tributaries flowed long enough into the season for rearing chinook to smolt and emigrate. Several lines of reasoning suggest that numbers, size diversity, and distance traveled upstream were lower than usual because of the atypical water year.
Most streams investigated showed signs of degradation resulting from human activities including construction of barriers, removal of woody debris and riparian vegetation, channelization, and changes in watershed runoff and erosion characteristics.
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