8206

• UCREFRP Catalog Number: 8206
• Author: Miller, W. J. and D. E. Rees.
• Title: Colorado Squawfish habitat use and movement during summer low flow in the Yampa River upstream of Cross Mounatin Canyon. Final Report.
• USFW Year: 1997.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

attempt to relocate Colorado squawfish 40:804. During the afternoon the area from RM 103.7
upstream to RM 105.0 was scanned by foot. Squawfish 40:804 was not relocated.
At various times during 24-hour observations Colorado squawfish were found occupying most of
the available habitats in the Yampa River. The 24-hour observations indicate that Colorado
squawfish utilized a variety of habitats and micro-habitats in the Yampa River, Colorado. The
range of habitats, depths and velocities used by Colorado squawfish were different between day
and night. During most environmental conditions (excluding events of high water and turbidity)
squawfish prefer deep pools during the day where they remain mostly inactive. Results of 24-
hour observations during the past two years suggest that most movement between habitats and
river locations occurs at night. Additionally the data suggests that foraging activity also occurs
at night. The specific area used during "foraging activity" probably depends on a variety of
environmental conditions as well as individual fish preference. The data suggests that the side
margins, and upper and lower ends of pools were used primarily during the low water condition
that prevailed during 1996. Observations during 1997 (a higher water year) indicate that most
fish moved into shallow runs or riffles during the night and showed a foraging type behavior
similar to 1996. The depths of most habitats used at night were shallower than habitats used
during the day. Colorado squawfish were located in or observed moving through a wide range f
velocities at night.
Habitat Use
Colorado squawfish almost exclusively used pools throughout the observation period from July
through October (Figures 62 and 63). Two of the five fish implanted did use run habitat but onl
occasionally during the entire eight weeks of observations conducted on the river. In addition,
one fish used an eddy pool, but less than 5% of the time of observation. Channel catfish used
pools most of the time but also used runs (Figure 64). Catfish used run habitat more frequently
than Colorado squawfish and is probably indicative of a difference in feeding behavior or gener.
habitat differences.
Northern pike, like Colorado squawfish, mainly used pools during the study. There was some
backwater habitat used by these fish. This was the only species that was observed using the
backwater habitat during the low flow period (Figure 65).
Observations in 1997 focused on 24 hour observations to develop a larger data set fbr daytime
and nighttime habitat use patterns for Colorado squawfish. There was a distinct difference ove
24 hour cycle for all of the squawfish. The fish showed what appeared to be a resting activity
during daytime hours and a feeding activity after sunset then returned to a resting mode at
sunrise. This pattern was shown in all of the 24 hour observations in 1997. The few 24 hour
observations conducted in 1996 also showed this pattern of behavior.
The combined 24 hour observations show a strong use of pool habitat and eddies in 1996 and a
pool and run use in 1997 based on the percent of time monitored (Figure 2). The daytime hou
contacts are very similar to that of the combined 24 hour observations, 1997 and 1996 (Figure
63).
Final Report - Colorado squash habitat Page 77
Miller Ecological Consultants, Inc. December 17, 1997
a