An experiment to control nonnative fish in the Colorado River, Grand Canyon, Arizona

Fact Sheet 2011-3093
By:  and 



The humpback chub (Gila cypha) is an endangered native fish found only in the Colorado River Basin. In Grand Canyon, most humpback chub are found in the Little Colorado River and its confluence with the Colorado River. For decades, however, nonnative rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta), which prey on and compete with native fish, have dominated the Grand Canyon fish community. Between 2003 and 2006, scientists with the U.S. Geological Survey and Arizona Game and Fish Department experimentally removed 23,266 nonnative fish from a 9.4-mile-long reach of the Colorado River near where it joins the Little Colorado River. During the experiment, rainbow trout were reduced by as much as 90% and native fish abundance apparently increased in the reach. Concurrent environmental changes and a decrease in rainbow trout throughout the river make it difficult to determine if the apparent increase in native fish was the result of the experiment.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title An experiment to control nonnative fish in the Colorado River, Grand Canyon, Arizona
Series title Fact Sheet
Series number 2011-3093
DOI 10.3133/fs20113093
Year Published 2011
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Southwest Biological Science Center
Description 2 p.
First page 1
Last page 2
Time Range Start 2003-01-01
Time Range End 2006-12-30
Country United States
State Arizona
Other Geospatial Grand Canyon
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details