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

I
I
I
I
I
I
I
I
I
,
I
I
I
I
I
I
I
I
I

shallow, sandy reaches and fish were trapped until sufficient flow reconnected
isolated pools.

Results of depletion sampling in low-flow refugia pools were consistent with
results from our general sampling at each site and validated that general sampling
adequately represented the fish community. In addition, results of sampling the
upper-site pool in 1995 were similar with results of sampling the same pool in
1 994. The same species were collected in both years except that channel catfish
were captured in 1994 and not in 1995. Total estimated number of fish of all
species in the refugia pool was similar in both years and was 310 in 1994 and 248
in 1995. Except for the lack of channel catfish in 1995, the percentage of each
species was strikingly similar in 1994 and 1995 (Figure 10).

The reasons why native species dominated the Little Snake River fish
community were unknown. The most obvious factors that could influence the fish
community in the Little Snake River are the hydrograph and its associated physico-
chemical characteristics such as water temperature, water quality, and sediment
transport. While similar in many aspects to the hydrographs of other unregulated
rivers in the basin, the Little Snake River hydrograph contains characteristics that
are often extreme, such as its peak to base flow ratio, its large sediment load, and
its extremely low base flow. In addition to abiotic factors, biotic factors probably
have an additional influence on the fish community in the Little Snake River,
especially the lack of large, predatory, nonnative gamefish. Community ecology
continues to debate the influence of abiotic and biotic parameters in shaping how
communities are structured and regulated (Heins and Mathews 1987) and the Little
Snake River provides an ideal location for focused studies to determine which
components affect fish distribution and abundance. Understanding differences in
physico-chemical components among Upper Colorado River Basin rivers will help

21