7733

• UCREFRP Catalog Number: 7733
• Author: McAda, C. W.
• Title: Evaluation of Aerial-Video Measurement of Backwaters as Part of the Interagency Standardized Monitoring Program for Age-0 Colorado Squawfish.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

In the laboratory, the video images were viewed on color monitors and captured in
' continuous overlapping frames along the length of the four study sites. The captured frames
were labeled to one-tenth of a river mile at the center of the frame. Backwaters and side
channels were identified and delineated on each frame. Channel width was measured at the
center of the frame. Number and area of side channels and backwaters, and channel width
were stored in text files and later loaded into a data management program. Each feature was
' identified by river mile (±0.1 mi). Complete details on collection and interpretation of
video data are provided by Pucherelli et al. (1990). A report describing the 1989 to 1991
' video data in more detail than intended here is being prepared by the Bureau.
This report summarizes.-only the video data describing number and area of backwaters
within the monitoring reaches.-- Computer files containing raw data were provided to the
Service by the Bureau. Number, area, and mean area of backwaters greater than 30 m2 in
' area (the minimum size of backwater sampled during ISMP) were summarized by monitoring
reach and by ten-mile intervals within each reach. These values were then compared with
' YOY Colorado squawfish data collected within each reach.
River Discharge
Mean-daily streamflow for the dates when ISMP sampling occurred and when aerial
' video was collected was obtained from USGS stream gauges. One USGS gauge occurs
within each of the four ISMP reaches (Figure 1). Total backwater area within each reach
was regressed against mean-daily streamflow on the day when video was collected to
' examine the relationship between the two parameters. Mean-daily streamflow was averaged
when video collection required more than one day.
YOY Colorado Squawfish
' Fall YOY Colorado squawfish monitoring data were collected by the Utah Division of
Wildlife Resources (UDWR) and Colorado Division of Wildlife (UDWR) according to
' criteria specified in the Monitoring Program Handbook (USFWS 1987). To compensate for
Colorado squawfish that might have been too small to identify in the field, and thus were not
' counted, samples identified in the laboratory were used to develop a 'correction factor.' This
correction factor was based upon the ratio of Colorado squawfish found in preserved samples
to those identified in the field. The number of Colorado squawfish found in unpreserved
' samples was multiplied by this number before catch-per-effort calculations were made
(Appendix Table Al).
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