Residence times and diel passage distributions of radio-tagged juvenile spring Chinook salmon and steelhead in a gatewell fish collection channel of a Columbia River dam
channel, chinook, Columbia River, juvenile, salmon, steelhead, McNary Dam, bypass, water velocity, salmonids, gatewells, Snake River, dams, migration
Journal or Book Title
North American Journal of Fisheries Management
The amount of time radio-tagged juvenile spring Chinook salmon (Oncorhynchustshawytscha) and juvenile steelhead (O. mykiss) spent within a gatewell and the juvenilecollection channel at McNary Dam, Columbia River, USA, was measured to determine the dielpassage behaviour and residence times within these portions of the juvenile bypass system. Themedian gatewell residence times were 8.9 h for juvenile Chinook salmon and 3.2 h for steelhead.Juvenile spring Chinook salmon spent 83% of their time in the 18-m-deep gatewell at depths of 9m or less, and juvenile steelhead spent 96% of their time in the upper 11 m. Fish released duringmidday and those released in the evening generally exited the gatewell in the evening, indicatingthat fish entering the gatewell during daylight will have prolonged residence times. Median collection-channel residence times of juvenile Chinook salmon were much shorter (2.3 min) thanthose of steelhead (28.0 min), most likely because of the greater size of the steelhead and thehigh water velocities within the channel (2.1 m/s). This and other studies indicate most juvenilesalmonids enter gatewells of several Columbia and Snake river dams in the evening and passinto the collection channels quickly. However, this is not consistent with the natural in-rivermigration patterns of these species and represents a delay in dam passage.