7145

• UCREFRP Catalog Number: 7145
• Author: Inslee, T. D.
• Title: Spawning of Razorback Suckers
• USFW Year: 1981.
• Copyright Material: NO

also need to be routinely scoured or will"fill with accumulated sediments
(Reiser et al. 1989). The creation and maintenance of backwaters is obvi-
ously an important function of high flows; these backwaters provide nurs-
ery habitat for early life stages of Colorado squawfish. For adult squaw-
fish, the mosaic of habitat types provided by a braided channel also
appears to be important.
We observed during our past radiotelemetry studies that adult Colorado
squawfish were often located in multi-channel areas or large, off-channel
habitats connected to the river. We hypothesized that adult squawfish were
selecting for sites with habitat heterogeneity over relatively homogene-
ous, single-channel habitats. To test this, we used data from our 1986-
1989 studies and mapped the locations of radio-tagged squawfish in the
Grand Valley to determine if complex or simple channel types were selected
in greater proportion than their relative availability. Using aerial
photos taken on 30 April 1986 and aerial video filmed on 2 August 1989, we
estimated the amount (percent) of river consisting of simple and complex
channel types during the higher flow conditions of spring and base flows
of summer and winter (we assumed winter channel conditions were similar to
summer conditions). We partitioned the river into 0.4-mile segments,
beginning at the Loma boat launch (RM 153.6) and proceeding upstream to
the Price Stubb Dam (RM 188.3). Each of the 89 segments was categorized as
either complex, if one or more islands, large backwaters, or side channels
were present, or simple if the segment consisted of a single channel with
no obvious secondary,'macrohabitat features. Locations of radio-tagged
fish either fell within a complex or simple 0.4-mile segment.
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