9350

• UCREFRP Catalog Number: 9350
• Author: Hawkins, J., T. Modde and J. Bundy.
• Title: Ichthyogauna of the Little Snake River, Colorado, 1995 with Notes on Movements of Humpback Chub.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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RK 135, 30-km upstream of our uppermost site (Marsh et al. 1991). Although
historical accounts suggest wider distribution and year-round occurrence, telemetry
data currently support only seasonal occupation of the Little Snake River by
Colorado pikeminnow and humpback chub (Miller et al. 1982; Wick et al. 1989).
The Little Snake River provided conditions similar to those in off-channel areas like
backwaters or small, flooded tributaries that contain abundant food, warmer water,
and lower velocity (Wick et a1.1983). Colorado pikeminnow and humpback chub
that move from the Yampa River into the warmer Little Snake River in the spring
and summer would optimize their growth and gamete production (Wick et al.
1989) .

Larval collections provided strong evidence of successful reproduction by
native species and limited or no reproduction by most nonnative species. No
endangered fish larvae were collected, although the identification of small Gila
larvae was problematic. We were able to distinguish between juvenile Gila species
that were preserved and examined in the laboratory and we found only juvenile
roundtail chub; but, there was still uncertainty with species identification of larval
Gila and this uncertainty will remain until valid phenotypic or genetic criteria are
developed and used to determine their identification.

Native fishes numerically dominated samples at all sites and seasons and
composed a high percentage 172%) of fish collected in the Little Snake River in
1995. Similar results were observed in 1994, when 69% of all fishes were native
(Hawkins et al. 1997), even though 1994 was a relatively dry year compared to
1995. One commonality in 1994 and 1995 hydrographs was the extremely low
baseflow that usually occurs regardless of runoff volume. In both years
composition of large-bodied species remained consistent and was dominated by
native flannelmouth sucker, blue head sucker, and roundtail chub (Figure 8). Only a
few of the large-bodied species collected were non natives; channel catfish, white

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