Office of External Affairs
Mountain-Prairie Region


U.S. Fish and Wildlife Service
Mountain-Prairie Region
134 Union Boulevard
Lakewood, Colorado 80228


April 20, 2011

Contact: Debbie Felker, Recovery Program

              303-969-7322, ext. 227

              Randy Hampton, Colorado Division of

             Wildlife – 720-398-7912 (cell)




LAKEWOOD, Colo. –  The Upper Colorado River Endangered Fish Recovery Program (Recovery Program) announced several biologically-driven changes to ongoing work that are aimed at continuing progress toward recovering four species of endangered fish found only in the Colorado River basin. The largest management adjustment this year is that nonnative smallmouth bass will not be translocated from the Yampa River to Elkhead Reservoir in northwest Colorado.  This change is a result of research that indicates that many smallmouth bass translocated since 2003 have escaped over the dam’s spillway during periods of high flows.  These adult fish reenter the Yampa River where they can find suitable spawning habitat and successfully reproduce. These escapees and their young continue to threaten the survival of endangered humpback chub, bonytail, razorback sucker and Colorado pikeminnow.

The Recovery Program increased efforts to reduce the number of smallmouth bass in the Yampa River eight years ago and has translocated nearly 6,000 fish to Elkhead Reservoir in an attempt to enhance sportfishing opportunities.

“Excessive numbers of smallmouth bass subsequently escaped from the reservoir and some were later found up to 100 miles downstream, undermining the effectiveness of the removal and translocation efforts,” said Recovery Program Nonnative Fish Coordinator Pat Martinez.  “Our concern goes beyond the individual fish that escaped.  Smallmouth bass quickly reproduce enabling the species to persist and spread and significantly limit the prospects for their reduction and control.”

As in the past, Recovery Program researchers will remove smallmouth bass from sections of the Yampa River this year.  All removed fish will be euthanized.

Nonnative northern pike are also of significant concern in the Yampa River.  The Recovery Program’s efforts to manage this large-bodied, predatory species in the Yampa River began in 1999.  Since then, ongoing removal efforts have resulted in a size shift from large fish that reproduce in high numbers and eat large prey, including adult native fish, to smaller fish that are less reproductive and somewhat less predaceous.

In addition to its assistance to the Recovery Program, the Colorado Division of Wildlife will continue work to control northern pike in the Yampa River upstream of Hayden. These upstream habitats have proven to be sources of northern pike in the upper Yampa River drainage.

Northern pike removed from the reaches of the Yampa River, in and downstream of Hayden, during spring removal efforts will be relocated to the Yampa State Park Headquarters pond to provide angling opportunities for the public.

“The headquarters pond makes sense as a translocation site,” said Randy Hampton, Colorado Division of Wildlife spokesman.  “The pond is easily accessible to anglers and we know that it will not reconnect to the river under any conditions.”

Northern pike captured during low flows in July will be removed and euthanized as researchers lack the resources to humanely relocate the fish at that time of year.

The Yampa River is regarded as one of the most important tributaries in the Upper Colorado River Basin (Upper Basin) for recovery of the four endangered fish species.  This is primarily due to its relatively unaltered patterns of seasonal flows and habitat which are important to the endangered fishes’ life cycle.  As the largest tributary to the Green River, the Yampa River provides habitat and delivers flows and sediment downstream to the Green River, helping to maintain a river system with hundreds of miles of habitat considered vital to the recovery of the endangered fishes.  It also provides important habitat for other native fishes including roundtail chub, bluehead sucker, flannelmouth sucker, speckled dace, mountain whitefish and mottled sculpin.

“The Yampa River serves as an example that every effort must be undertaken to prevent northern pike and smallmouth bass from reaching critical habitat in other rivers within the Upper Basin,” Martinez said.  “These species have inflicted severe ecological damage to the native food web in the Yampa River.  Their proliferation devastates the native aquatic community that is required to allow and sustain endangered fish recovery and increases the likelihood that additional native species may become threatened or endangered.”

Recovery Program nonnative fish management efforts will take place from April through October in more than 500 miles of the Upper Basin, including the Colorado, Gunnison, Duchesne, Green and Yampa rivers in the states of Colorado and Utah. Biologists from the Colorado Division of Wildlife, Larval Fish Laboratory at Colorado State University, the Utah Division of Wildlife Resources, the Ute Indian Tribe Fish and Wildlife Department and the U.S. Fish and Wildlife Service will conduct the work.

Nonnative fish management is one of many recovery actions that enables use and development of water from the Upper Basin to proceed in compliance with the Endangered Species Act (ESA).  Since 1988, recovery actions implemented by the Recovery Program have provided ESA compliance for 1,846 water projects depleting more than 2.8 million acre-feet of water in the Upper Basin.

Researchers will also conduct other studies related to endangered fish recovery this year.  These include data collection to estimate the abundance of Colorado pikeminnow and humpback chub; monitoring floodplain habitat and sediment; and monitoring razorback sucker reproduction through collection of their larvae.  In addition, hatchery-raised bonytail and razorback sucker will be stocked in sections of the Green, Gunnison and Colorado rivers to help reestablish populations.

For more information, contact the Recovery Program at 303-969-7322, ext. 227, or visit the Recovery Program’s website at


The Upper Colorado River Endangered Fish Recovery Program is a cooperative partnership of local, state and federal agencies, water organizations, power customers and environmental groups established in 1988 to recover the endangered fishes while water development proceeds in accordance with federal and state laws and interstate compacts.




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