7799

• UCREFRP Catalog Number: 7799
• Author: Modde, T. and D. Irving.
• Title: Conceptual Management Plan for Habitat Enhancement In Old Charley Wash.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

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(faba et al. 1965), two fish, 37 and 39 mm , in 1991 (Brandt Gutermuth, Ut ah Division of Wildlife

Resources; Personal Communication) in low gradient sites of Colorado River above Lake Powell, and a

single 59 mm fish collected on the Ouray National Wildlife Refuge in 1993 by the Utah Division of Wildlife

Resources (Daryl Snyder, Larval Fish Laboratory, Colorado State University; Personal Communication). Tyus

and Karp (1990) observed that razorback sucker spawn during increasing and peak spring flows and

suggested that flooded bottomlands may be important habitats necessary for recruitment. Modde et al.

(in prep) reported limited recruitment of the razorback sucker in the Middle Green River and showed a

significant correlation in the number of small razorback sucker ( < 475 mm) collected between 1 980 and 1992

with spring flow magnitude five years prior to their collection. Discovery of several hundred razorback

sucker of the apparent same age in Etter Pond adjacent to the Colorado River in 1991 (Frank Pfeifer, U.S

Fish and Wildlife Service: Personal Communication), isolated since the 1984 flood. suggests these flooded

bottomlands adjacent to the main channel are important to recruitment. Larval razorback sucker stocked

into isolated coves in Lake Mohave (Mueller et al. 1993) and a gravel pit adjacent to the Colorado River

(Osmundson and Kaeding 19a9) demonstrated rapid growth and relatively high survival. Given the limited

information available, it appears recruitment of razorback sucker is likely associated with high flow events,

most notably with the availability of flooded bottomlands. The importance of flooded bottomlands to growth

and the recruitment of riverine species Is documented by Welcomme (19a9).

The periodicity of out-of-channel flooding in the Green and Colorado Rivers has dramatically

decreased following the onset of water diversion practices and the construction of main stem dams

(Osmundson and Kaeding 1991). In addition to the reduced spring flow peaks, major wetlands in the Middle

Green River have been diked to either protect agriculture operations or provide waterfowl nesting habitat

(i.e. Stewart Lake State Management Area, and Ouray National Wildlife Refuge). The presence of dikes has

prevented access of both larval and adult life stages into these warmer and productive habitats in the spring

months. At extremely high flows when water has spilled over the dikes at the Ouray National Wildlife Refuge

adult razorback sucker were observed to use these flooded bottomlands (fyus 1987).

Riparian enhancement in the Upper Colorado River Basin can be accomplished by removing water

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