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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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Template:
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 />According to Bovee (1982), when field observations do not verify the <br />conclusions of the SI curves in question, it is customary to modify the curves <br />to reflect the habitat selection. Thus for comparison a second set of SI <br />curves were developed to include the mean depths and velocities observed by <br />Tyus, Jones and Trinca. It is assumed that the means observed represent <br />optimum habitat, and therefore, they have been assigned a rating of one. It <br />is likewise assumed that as long as a minimum depth is maintained, depth will <br />not influence habitat selection. More likely a species will move up and down <br />in the water column until a suitable velocity is found (Figures 4 and 5). <br /> <br />Table 4. <br /> <br />List of the optimum and mean depth and velo6ity microhabitat <br />implied from the SI curves for Colorado squawfish and razorback <br />suckers compared to the mean values observed by Tyus, Jones and <br />Trinca (1987). <br /> <br />------------------------------------------------------------------------- <br /> <br />SI curve value <br />DeDth 1f1l Velocity (ft/sl <br /> <br />Observed value <br />DeDth eft) Velocity (ft/s) <br /> <br />0.82 <br />1.58 <br /> <br />No Data <br />1.64 <br /> <br />Using the modified SI curves the Colorado squawfish have a minimum optimum <br />depth of 5.18 with velocities between 0.00 and 0.82 ft/s, and the depositional <br />life stage has an optimum depth at 2.04 ft and velocity between 1.58 and 2.27 <br />ft/s. The optimum depth for razorback sucker is at 5.08 ft with velocities <br />between 0.00 and 0.34 ft/s in May and June, and 3.44 ft with velocities <br />between 1.64 and 1.68 ft/s from July to August. <br /> <br />During the development of the curve sets (Valdez et al. 1987), a rating from A <br />to F (A being the highest), was assigned to each curve as a measure of the <br />relative confidence the biologists had in each curve set. The rating was an <br />indication of the relative accuracy of the SI curves to depict microhabitat <br />use. The curve set for Colorado squawfish adults (size 5; 400+ mm) was <br />assigned a confidence rating of "A" for the depth, velocity and substrate <br />curves. The curve set for the deposition life stage was assigned a "C-" <br />because of the small sample size (n=21) and limited number of spawning sites <br />from which the data were collected. The razorback sucker curve sets were both <br />given a "C" rating, because of small sample size (n ranges from 11 to 32). <br />The ratings given each curve by the panel of species experts serve as a <br /> <br />, <br />i <br />I <br />1 <br />~ <br />I <br /> <br /> <br />i <br /> <br />11 <br />
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