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<br /> <br /> <br />temperatures (12-1700) were similar for spawning areas at both <br />Senator Wash Reservoir and Lake Mohave (AZ/1NV), suggesting <br />specific spawning site requirements (Ulmer 1981). <br />Adult and sub-adult razorback suckers reportedly utilize <br />backwater habitats in the upper Colorado River basin. These <br />backwaters (near Grand Junction, CO) are large gravel pits and <br />somewhat resemble the quiet water off-•channel areas in the lower <br />basin. Although razorbacks have been found sporadically <br />throughout lower basin irrigation systems in recent years, <br />collections have been few in backwater sampling efforts. <br />A survey utilizing this recent information was conducted to <br />determine the status of the razorback sucker in the lower Colorado <br />River. The primary objectives were to locate and describe the <br />relative abundance and determine the status of the remnant <br />population from Parker. Dana south to Morelos Dam. Secondarily, <br />stratified graphing of the mainstream habitat was completed to <br />scan the "hard to sample" areas for fish and depict channel <br />characteristics and restrictions for future reference. <br />MATERIALS AND METHODS <br />The U.S. Bureau of Reclamation (USBR) has geographically <br />divided the lower Colorado River system into 10 administrative <br />V <br />d