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e e 't LOWER COLORADO RIVER AREA COORDINATOR REPORT William E. Rinne Water and Power Resources Service Lower Colorado Region Boul der City, Nevada Research and review of status of several species of native fishes continues to receive emphasis in the lower Colorado area this year. The status of the razorback sucker (Xyrauchen texanus) is of major concern in this area. The time limit to list the razorback as threatened on the Federal list expired on April 24, 1980. An Ad Hoc Committee of biologists with state, university, and Federal agencies recently began reviewing and updating the 1975 razorback management plan, developing a plan to insure the survival of this species in the immedi ate future, and cons idering the need for reproposing razorbacks for listing on the Federal list. The first year of the cooperative study on razorbacks in Senator Wash Reservoir near Yuma, Arizona nears completion. This study is under the direction of the California Department of Fish and Game and significant data has been gathered on movements, spawning behavior, spawning requirements and population density of razorbacks in Senator Wash. The Water and Power Resources Service (Water and Power) is one of the participating agencies. Some work ;s planned for the mainstream of the Colorado River this year. Water and Power, Boulder City, Nevada 1S in the process of negotiating procurement of a 2~-year study on the razorback sucker and the bony tail chub (Gila elegans) in Lake Mohave, Nevada/Arizona. This study will be designed 1.0 determine: the present status, biology and distribution of these fish in Lake Hohave, Nevada/Arizona; and the effect of construction and opera- tion of proposed Water and Power projects in this area. The bOQytail chub (G.ila Elegans) was listed as endangered (May 23, 1980). Recent surveys indicate that it is presently found only in lake Mohave (Federal Register, Vol. 45, No. 80, April 23, 1980). Intensive samp1 ing was conducted in Lake Mohave in the spring of this year in an attempt to collect brood stock for artificial propagation studie.s at Willow Beach Fish Hatchery. A total of 5 bony tails, all females, were captured and transported to Willow Beach, Arizona. Water and Power, Boulder City, is preparing to contract a study to further investigate the biology and status of bony tails in Lake ~'1ohave. This study may be initiated as early as February 1981. Spring and fall surveys of woundfin (Plagopterus argentissumus) have been completed by the members of the Recovery Team in the