Projects and Research

Nonnative Fish Management

We recover endangered fish while also working to minimize the impacts of non-native sport fishing. In general, stocking nonnative fish species in the upper Colorado River basin has been confined to areas where there is little potential conflict with endangered fish.

Population Monitoring

Field studies emphasize quantitative estimates of population size and determination of basic life history and habitat requirements. Populations estimates of Colorado pikeminnow and humpback chub are being conducted to determine if these two species are progressing to where downlisting can occur. Because these species declined prior to any knowledge of their life history, basic questions on early life history are being answered, particularly with razorback sucker and bonytail and the role of floodplains as nursery areas for these species.

Floodplain Restoration

Habitat enhancement in the Green River sub-basin has also addressed floodplain restoration. Inundated floodplains provide critical nursery and adult habitat for endangered fishes. Floodplain restoration actions have included breaching or removal of several levees to increase the frequency of floodplain connection to the river, and improvement of water control structures to increase management options on the Ouray National Wildlife Refuge and adjoining Bureau of Land Management lands on the Green River.

Instream Flow Recommendations

Instream flow recommendations have been either completed, or are in some stage of approval, for all mainstem reaches and major tributaries of the Upper Colorado River Basin that support the ‘large river’ endangered fishes. Flow recommendations developed by the GRB FWCO are being used by Fish and Wildlife Service Ecological Services staff to update biological opinions for the Yampa and Duchesne rivers. Data collected by our office also contributed to the flow recommendations in the Green River and operation of Flaming Gorge Dam. Habitat enhancement in the Green River subbasin has emphasized instream flow needs and floodplain restoration. All flow recommendations are subject to state law and existing water rights.