2009 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 spring Chinook escapement to the upper basin. The DIDSON continuously recorded sequential 1-hour files from late May until late September 2009, 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 2009 spring Chinook escapement to the upper basin of 24 fish (95% confidence interval = +/- 4). This estimate is higher than the estimate of 12 fish based on an expansion of the total redd count for the year (4 redds, times an expansion factor of 3 fish per redd). A brief discussion of possible reasons for this difference is provided.
Galbreath, P.F., C.R. Frederiksen, P.E. Barber, and S-Y. Hyun. 2010. 2009 spring Chinook escapement to the upper basin of the Klickitat River based on DIDSON sonar counts. Columbia River Inter-Tribal Fish Commission Technical Report 10-1. Portland, OR. 18p.