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WSP12033
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Last modified
1/26/2010 3:19:40 PM
Creation date
10/12/2006 5:21:34 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8240.200.46.J
Description
Ruedi Reservoir
State
CO
Basin
Colorado Mainstem
Water Division
5
Date
3/1/1995
Title
Report to the Colorado Water Conservation Board on 1994 Water Releases from Ruedi Reservior for Endangered Fish Habitat in the 15-Mile Reach of the Colorado River
Water Supply Pro - Doc Type
Publication
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<br />Conclusions <br /> <br />Endangered fish releases from Ruedi Reservoir have proven to be an effective <br />means for augmenting flows in the IS-Mile Reach during the critical low summer <br />months. Response of the 15-Mile Reach population of squawfish to improved <br />habitat conditions will be difficult to assess until targeted flow regimes can <br />be met and extended for a number of consecutive years. Improved habitat <br />should, over time, translate to a higher carrying capacity for this stretch of <br />river resulting in an increase in population size, assuming that proper flow <br />and habitat conditions are met during the other months of the year. At <br />present, the 15-Mile Reach remains an important stretch of river for adult <br />squawfish. During 1991, 23 adult squawfish were captured and released. In <br />subsequent years 1992, 1993 and 1994, 22, 17, and 21 adult squawfish were <br />captured respectively. Of the fish captured, a small percent were recaptures <br />which indicates that capture rates reflect a small subset of the total adult <br />fish utilizing the habitat. Comparing catch rates on a number-per-mile basis, <br />they were more than double that of anywhere else in the Colorado River. The <br />population of squawfish is estimated to be around 200 adults in the upper <br />river (Palisade to Westwater Canyon), This population is expected to increase <br />in the next few years as a result of recolonization to the I5-Mile Reach by <br />fish produced in the 1985 to 1987 period, These fish now reside in the lower <br />river and current trends indicate fish are moving to and occupying habitats in <br />the upper river, The life history requirements of squawfish which include <br />spawning in the 15-Mile Reach, drifting to the lower river to grow several <br />years and then returning to upstream areas as adults, complicates the <br />assessment of fish distribution and abundance. The relatively short period in <br />which flows have been managed for endangered fish in comparison to the life <br />history requirements of the fish make it difficult to detect the benefits of <br />Ruedi releases. <br /> <br />Larval squawfish sampling began in the Reach in 1982 and has continued until <br />present. Intensive larval collection began in 1991 and data from this work <br />has not been completely analyzed because of backlogs at the CSU Larval Fish <br />Lab which must identify the sample under a microscope. Indications are that no <br />squawfish larva have been captured, Young of-the-year squawfish are <br />consistently collected in the 18-Mile Reach between Grand Junction and Loma, <br />but none have been captured in the 15-Mile Reach. Adult squawfish occupy the <br />15-Mile Reach during spring which suggests that spawning occurs in the 15-Mile <br />Reach but the young immediately drift downstream to nursery areas. <br /> <br />Monitoring of the 15-Mile Reach by fishery biologists between 1991 and 1994 <br />have identified a distinct increase of other natives. There is a strong <br />cohort of roundtail chub, a candidate species that has appeared in the 15-Mile <br />Reach indicating increase in population size. The roundtail chub is a <br />category II species for listing under the Endangered Species Act. <br /> <br />Attachments <br /> <br />7 <br />
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