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Last modified
8/11/2009 11:32:56 AM
Creation date
8/10/2009 3:25:01 PM
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UCREFRP
UCREFRP Catalog Number
7347
Author
Wick, E. J. and J. A. Hawkins.
Title
Observations on Use of the Little Snake River in Colorado, by Endangered Colorado Squawfish and Humpback Chub, 1988.
USFW Year
1989.
USFW - Doc Type
Fort Collins, Colorado.
Copyright Material
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<br />Pools inside and outside the canyon tended to hold large concentrations of <br />fish which were readily observable from above. <br />DISCUSSION <br />Possible reasons that Colorado Squawfish are attracted to the Little <br />Snake River might include a preference for warmer temperatures and increased <br />feeding opportunities. Colorado squawfish are known to use warmer backwater <br />and flooded gulches on the Yampa River during spring run-off (Wick et al. <br />1983). Warmer water temperatures and feeding is important in conditioning <br />fish for migration and spawning (McKeown 1984). Backwater habitat is not as <br />abundant in the Lily Park area of the Yampa River as it is in upper portions <br />of the Yampa (Wick et al. 1986). The Little Snake River could provide warm <br />water habitat to squawfish within it or in the Yampa River below the <br />confluence. Reproduction of native fishes in the Little Snake River is <br />occurring, thus providing an important spawning area for these species and <br />possibly a food source for squawfish. Temperature variations in habitats used <br />by Colorado squawfish could influence the timing of spawning migrations and <br />spawning (Wick et al. 1983). Colorado squawfish using the warmer waters of <br />the Little Snake River might undergo an earlier spawning migration than fish <br />residing solely within the Yampa River. This variation could result in <br />prolonged use of the spawning area in Yampa Canyon due to the arrival of <br />squawfish at different times. If spawning habitat is in short supply this <br />could maximize its utilization because of the lengthened spawning period. <br />Colorado squawfish larvae usually hatch after most sucker and roundtail <br />chub larvae have hatched. Larval collections indicated that suckers had just <br />hatched and roundtail chub had probably not completed spawning. Based on size <br />and development, flannelmouth sucker spawned prior to bluehead sucker and it <br />appeared that roundtail chub larvae were just beginning to hatch. Since <br />Colorado squawfish spawn later than Gila species, our larval sampling <br />indicated that adult Colorado squawfish probably left the Little Snake River <br />prior to spawning. Migration of the radiotagged Colorado squawfish from the <br />Little Snake River to the Yampa River spawning area indicates that this fish <br />probably spawned in Yampa Canyon. However, spawning of Colorado squawfish can <br />not be discounted completely since we only sampled larvae on one date. <br />Intensive larval sampling over an extended time period is recommended. <br />Flows on the Little Snake River declined rapidly in June, from over 2000 <br />ft'/s in early June to below 400 ft'/s during late June larval sampling. The <br />two radiotagged Colorado squawfish left the Little Snake River in mid to late <br />June, prior to June 26, possibly in response to decreasing flows. In July, <br />flows declined to below 100 ft' /s by the 10th and below 10 ft%s by the 20th. <br />Presence of humpback chub in canyon sections of the lower Little Snake <br />Rivet appears to be restricted to the run-off period similar to the period of <br />use by Colorado squawfish. It is possible that humpback chub spawn within the <br />Little SnE'e River since two of the seven humpback chub collected were <br />tuberculated; however, larval collections will need to be made to verify <br />spawning success. Humpback chub that move into the Little Snake River during <br />the high water period might be attracted to the canyon area because of the <br />relatively deep, turbulent eddys which are habitats typically associated with <br />the species (Valdez et al. 1982). Although humpback chub are associated with <br />high turbulent flows, they are often collected in low velocity waters nearby <br />(Valdez et al. 1982). When flows decline humpback chub apparently leave the <br />7
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