Department of the Interior
Office of the Secretary
August 3, 2006
|Contact: Kip White, 202-513-0684
Assistant Secretary Limbaugh Comments on USGS Finding
Endangered Humpback Chub Population in Grand Canyon
|Click on the image above for High Resolution
The number of adult humpback chub, Gila cypha, in Grand Canyon has stabilized between 2001 and 2005 after years of decline, USGS biologists say. The endangered freshwater fish is found only in the Colorado River Basin.
WASHINGTON -- Interior Assistant Secretary for Water and Science Mark Limbaugh made the following statement today regarding the U.S. Geological Survey's announcement that recently collected data show that the endangered humpback chub population in Grand Canyon is stabilizing. Increases in young fish were also announced for other native fish species in the Grand Canyon. The USGS report indicated that fish management changes approved in 2002 appear to be helping the endangered fish.
"This is a hopeful sign for the humpback chub and the other native fish, though we'll need to continue our work to protect these species. I am encouraged by the U.S. Geological Survey's finding that the number of adult humpback chub in Grand Canyon stabilized between 2001 and 2005 after more than a decade of decline. The USGS studies also found increased abundance of juvenile humpback chub and other native fish species between 2003 and 2005 near the confluence of the Colorado and Little Colorado Rivers, where these species are known to spawn."
Limbaugh is the Secretary of the Interior's official representative on the Glen Canyon Dam Adaptive Management Work Group. Known as the "AMWG," the group evaluates scientific studies of the Colorado River ecosystem in Grand Canyon and makes recommendations to the Secretary on modifications to dam operations, experiments, and other management actions that can help to protect the river's natural and cultural resources.
Limbaugh added, "Both the mechanical removal of large numbers of rainbow and brown trout and a combination of experimental dam releases were recommended by the Adaptive Management Work Group and approved by Interior in 2002. These experiments were based on the Adaptive Management Program's extensive research and monitoring of natural resources in this part of the Colorado River and appear to have contributed to improved spawning and rearing conditions for the humpback chub.
"Protecting and recovering the endangered humpback chub, which is found only in the Colorado River Basin, is a major goal of the Glen Canyon Dam Adaptive Management Program. Though more studies will be needed to fully understand this improvement, the USGS report suggested that the primary contributing factors were likely the experimental removal of nonnative, competitor fish, experimental water releases from the dam and drought-induced river warming.
"The adaptive management approach is founded on a rigorous, science-based program that promotes flexible decision-making that can be adjusted as we learn more about the complexities of the Colorado River/Glen Canyon Dam system. I look forward to further recommendations from the Adaptive Management Working Group on modifications to dam operations and other management actions."
The USGS news release and fact sheet on these recent findings are available at www.doi.gov as well as on the USGS website at www.usgs.gov and at www.gcmrc.gov/research/humpback_chub/20060802.htm.