9406

• UCREFRP Catalog Number: 9406
• Author: Osmundson, D. B.
• Title: Importance of the '15-Mile Reach' to Colorado River Populations of Endangered Colorado Pikeminnow and Razorback Sucker.
• USFW Year: 2000.
• USFW - Doc Type: Grand Junction.
• Copyright Material: NO

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5
4
3
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1
0
1 2 3 4 5 6 7 8 .9
Study strata
15-mile reach
Figure 4. Longitudinal variation in densities of adult Colorado pikeminnow in the Colorado
River. Fish per mile was calculated using annual population estimates (1991-1994 and 1998-
1999) for the lower (strata 1-6) and upper (strata 7-9) reaches, proportion of fish captured
each year greater than 550 mm, and correction factors that account for effort per stratum and
miles per stratum. See Fig. 1 for strata locations and Osmundson and Burnham (1998) for
sampling methodology.
650
600
E
E 550
s
500
a?
450
(D
400
350
1 2 3 4 5 6 7 8 9
Study strata
Figure 5. Longitudinal variation in mean length of Colorado pikeminnow captured with
trammel netting and electrofishing in the Colorado River. Values are means of annual means
1991-1994 and 1998-1999). See Fig. 1 for strata locations and Osmundson and Burnham
1998) for sampling methodology.
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