9432

• UCREFRP Catalog Number: 9432
• Author: Modde, T. and M. Fuller.
• Title: Feasibility of Channel Catfish Reduction in the Lower Yampa River.
• USFW Year: 2002.
• USFW - Doc Type: Vernal.
• Copyright Material: NO

the alluvial reaches of the Yampa River would be cheaper and more efficient.

The ability to reduce channel catfish density in the Yampa River may be the result of

vulnerability of fish to active capture techniques. The Yampa River has a relatively narrow

channel in which fish are more effectively collected than in larger alluvial reaches of the mainstem

Green or Colorado rivers. The ability to sample much of the available habitat with active capture

techniques was more effective than passive collecting gear. Tyus and Nikirk (1990) also recorded

much higher capture rates of channel catfish in the lower Yampa River (Yampa Canyon) than in

the Green River, although relative densities were believed to be similar between the two areas

(Tyus et al. 1982). Thus, in the upper Colorado River basin, mechanical removal of channel

catfish can be successful using active sampling gear in tributaries (i.e., smaller systems than the

mainstem). Because growth rates of channel catfish are slow (Tyus and Nikirk 1990), if

recruitment could be lowered by reduction in the number of spawning adults above the affected

area, i.e., Yampa Canyon, the impacts of nonnative fish reduction would be longer lasting.

Conclusions

1. In three of four removal (treatment) reaches of the Yampa River in Dinosaur National

Monument, channel catfish numbers were significantly reduced following removal efforts

in 1999.
2. The more effective methods of removing channel catfish from the Yampa River was by

angling and electrofishing.

3. A gradient in total length of fish occurred in which smaller fish were found downstream in

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