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Methods <br />Relative abundance of adult Colorado squawfish and razorback sucker (as <br />described by the catch of fish per unit of sampling effort) was estimated <br />using electro-fishing. Timers on electrofishing units recorded actual <br />shocking time (seconds) during each sampling effort. The number of Colorado <br />squawfish or razorback sucker captured per hour of shocking was used as the <br />standard unit of relative abundance. All areas within a reach did not <br />receive equal shocking effort and thus searches should not be considered <br />systematic. Although both shorelines and all large backwaters of each reach <br />were sampled, those areas where squawfish or razorback suckers were found <br />were subsequently searched more intensively. <br />Radiotelemetry was used to follow movement of adult Colorado squawfish and <br />razorback sucker, as well as to identify the microhabitats used by these <br />fish. Electrofishing boats and trammel nets were used to capture fish. <br />' Fish longer than 550 mm total length (TL) and captured from within the 15- <br />mile reach were surgically implanted with radio transmitters following <br />' procedures outlined by Tyus (1982). Various sizes of transmitters were used <br />depending on fish size. Battery life of the smallest transmitter is <br />' estimated as 150-245 days; the largest, 547-940 days. All captured rare <br />fish were measured to total length, weighed, and had a numbered Carlin tag <br />attached to them. Fish were released at their location of capture. The <br />river was searched for radio-tagged fish on a weekly basis. The area <br />routinely searched included the 35 miles of the Colorado River between the <br />Price Stub Dam (three miles upstream from the upper end of the 15-mile <br />reach) and the Loma Boat Launch, and the lower 2.2 miles of the Gunnison <br />River (the reach downstream from the Redlands Diversion Dam). The search <br />2