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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sucker, and common carp each composed only a small portion (< 3%) of the fish
collected. Most small-bodied species were nonnatives in both 1994 and 1995 and
their composition varied each year (Figure 9). Speckled dace were the most
commonly collected native small-bodied species and redside shiner and sand shiner
were the most commonly collected nonnative species. Red shiner, fathead
minnow, and mottled sculpin composed a very small portion of small-bodied species
in both years. Creek chub and plains killifish were few and only collected in 1995.
The high proportion of native fishes found in the Little Snake River was unusual
compared to most Upper Colorado River Basin mainstream rivers that are typically
dominated by nonnative fishes lCarlson and Muth 1989, Hawkins and Nesler
1991); although, it was similar to the high percentage (72%) observed in the Price
River, a similar-sized tributary of the Green River (Cavalli 1999).

Species composition was relatively similar at all reaches even with wide
(> 34 km) separation of sites and different geomorphological conditions at each
site. The longitudinal differences of a few species were probably due to different
thermal tolerance, but for species that were more abundant in the lower reach their
abundance could also be due to infiltration from the Yampa River. Red shiner, a
warm-tolerant species, was more abundant in downstream reaches than it was in
cooler, upstream reaches. Cool tolerant, reds ide shiner, were more abundant in
cooler upstream sites and as water temperatures increased in autumn their
abundance declined. Abundance of most other species remained relatively constant
through all seasons showing that most species collected in the Little Snake River
could remain there as year-round residents. Although some individuals left the
Little Snake River, such as telemetered roundtail chub, humpback chub, and
Colorado pikeminnow, others apparently remained in the Little Snake River well
after runoff declined to base flow and when diel temperature fluctuations were
extreme. During baseflow, most refugia pools were isolated by impassible,