2010 Spring Chinook Escapement to the Upper Basin of the Klickitat River Based on DIDSON Sonar Counts
A Dual-Frequency Identification Sonar (DIDSON) sonar was deployed to observe fish passage through the Castile Falls Fishway on the Klickitat River, and to obtain an estimate of 2010 spring Chinook Oncorhynchus tschawytscha escapement to the upper basin. The DIDSON continuously recorded sequential 1-hour files from mid May until September 2010, except for occasional interruptions due to technical problems. “Echograms” were processed from the original DIDSON video files, and upstream passage events observed in the echograms of large fish deemed to be spring Chinook were noted. The resulting data were analyzed to account for periods when DIDSON files were unavailable, producing an estimate for total spring Chinook escapement to the upper basin of 26 ± 1 fish (95% confidence interval). This estimate bears witness to a substantial level of escapement of spring Chinook which was not detected through spawning surveys conducted in 2010, during which only a single redd was counted. Based on a 3 fish per redd expansion factor, the expected redd count for the DIDSON-based escapement estimate would have been approximately 9 redds.
Supplemental Material – DIDSON Sonar Video
Galbreath, P.F., C.R. Frederiksen, P.E. Barber and R.B. Lessard. 2011. 2010 Spring Chinook Escapement to the Upper Basin of the Klickitat River Based on DIDSON Sonar Counts. Columbia River Inter-Tribal Fish Commission Technical Report 11-1, Portland, Oregon. 20p.