U.S. Geological Survey Fact Sheet 2009-3035
The Colorado River Basin supports one of the most distinctive fish communities in North America, including the federally endangered humpback chub (Gila cypha). One of only six remaining populations of this fish is found in Grand Canyon, Arizona. U.S. Geological Survey scientists and their cooperators are responsible for monitoring the Grand Canyon population. Analysis of recently collected data indicates that the number of Grand Canyon adult humpback chub—fish 4 years old and older and capable of reproduction—increased approximately 50 percent between 2001 and 2008. When possible model error is considered, the estimated number of adult chub in the Grand Canyon population is between 6,000 and 10,000. The most likely number is estimated at 7,650 individuals.
First posted April 27, 2009
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Andersen, Matthew E., 2009, Status and trends of the Grand Canyon Population of humpback chub: U.S. Geological Survey Fact Sheet 2009-3035, 2 p. [https://pubs.usgs.gov/fs/2009/3035/].
Monitoring the Humpback Chub Population
Causes of the Population Increase
Experimental Water Releases
Removal of Nonnative Fish