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Last modified
7/14/2009 5:02:29 PM
Creation date
5/20/2009 3:42:12 PM
Metadata
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UCREFRP
UCREFRP Catalog Number
7245
Author
Rose, K. L. and D. R. Hann.
Title
Consolidated Instream Flow Report, Habitat Modeling on the Green River Using the Physical Habitat Simulation System.
USFW Year
1989.
USFW - Doc Type
Grand Junction, Colorado.
Copyright Material
NO
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<br />4. Habitat Suitability Criteria <br /> <br />The response of a species during a particular life stage (e.g. Colorado <br />squawfish adult) to a streamflow dependant variable (e.g. velocity) is <br />mathematically described as a habitat suitability index (SI) curve. These <br />curves are based on the assumption that individual fish tend to inhabit the <br />most favorable microhabitat conditions from within the total range of <br />conditions present. They will use less favorable conditions with lesser <br />frequency and will eventually leave the area before microhabitat conditions <br />become lethal. The value of each variable represented by an SI curve ranges <br />from 0 to 1 with a rating of one assigned to the value which provides optimum <br />habitat conditions for the species. <br /> <br />51 curves for some life stages and for certain specified times of the year <br />have been developed for Colorado squawfish, humpback chub, and razorback <br />sucker for use in a PHABSIM analyses (Valdez et. al. 1987). Four curve sets <br />were available for this analysis. They include curves for Colorado squawfish <br />adult and depositional life stages from April through October and mid-June to <br />September, respectively, and for adult razorback suckers from May through June <br />and July through October (Figures 2 and 3). From the SI curve set for <br />Colorado squawfish, it is concluded that the adult life stage utilizes depths <br />around 5.18 ft with 0.00 feet per second (ft/s) velocities over sand <br />substrate, while the depositional life stage utilizes depths of 2.04 ft with <br />velocities around 2.27 ft/s over rubble substrate. Adult razorbacks utilize a <br />depth of 5.08 ft, with a velocities between 0.00 and 0.34 ft/s over sand <br />substrate from May to June, and depths of 3.44 ft with 1.68 ft/s velocities <br />over sand substrate from July to October. To verify these conclusions <br />obtained from the SI curves the theoretical optimum depths and velocities were <br />compared to the mean microhabitat values reported in Tyus, Jones and Trinca <br />(1987; Table 4). According to these authors, adult Colorado squawfish occupy <br />a variety of habitats with mean depths and velocities of 1.8 meters (m) (5.9 <br />ft) and 0.25 meters per second (m/s) (0.82 ft/s), respectively. They are <br />found predominately in eddies and runs along shorelines, over sand and silt <br />substrates. In contrast, the SI curve suggests a theoretical optimum velocity <br />of 0.00 ft/s. The breeding adults deposit and fertilize eggs on cobble bars <br />with mean depths and velocities around 3.09 ft and 1.58 ft/s (Tyus et. al <br />1987). This is slightly deeper and slower than optimums predicted by the SI <br />curves (2.04 ft and 2.27 ft/s; Figure 2). The razorback sucker uses main <br />channel habitat in depths ranging from 0.6 to 3.4 m (1.97 to 11.16 ft) and are <br />most common in runs near shore in spring, and on main channel sand bars <br />composed of unconsolidated coarse sand in summer. Water depths on the sand <br />bars were usually less than 2 m (6.56 ft) with an average water velocity of <br />0.5 m/s (1.64 ft/s). In general these habitat descriptions coincide with the <br />depth/velocity ratings represented by the SI curves for razorback suckers. <br /> <br />8 <br />
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