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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />in the Upper Colorado and Gunnison Rivers (McAda 2000; Anderson 1999). The upstream <br />movement may be in response to fish searching for suitable spawning habitat to be used the <br />following year or fish seeking new upstream feeding areas following spawning for the current <br />year (Burdick 2000c). During the first five years of operation of the Redlands fish passageway, <br />the months of highest usage for all fishes were June and July, with fish passage continuing into <br />August (Burdick 2000c; Pfeifer 2000b). <br />Analyses of flow records indicate that the peak spring runoff occurs on the Gunnison <br />River during mid-May to mid-June. Thus, the period when both endangered fish are migrating <br />is typically April to August. <br />The razorback sucker and the Colorado pikeminnow are believed to have a life span of <br />at least 30 and 20 years respectively (Pfeifer 2000b). Given the long life span of these fish it <br />has been theorized that migration and spawning every year may not be necessary for the <br />survival of these species. To date it is not known if the fish must migrate to spawn nor is it <br />known if the fish must spawn every year to survive. Under natural conditions, with a wide <br />range of flows, it is possible that there were years when these fish species were not able to <br />migrate to their spawn sites due to low flow conditions (Pfeifer 2000b). Similarly there will be <br />years when the flows in the Gunnison River will be too low to operate the fish ladder <br />simultaneously with the Hartland diversions. <br />3.2 Swimming Ability <br /> <br /> <br />Razorback suckers have been tested for swimming performance. Earlier tests <br /> <br />indicated that the razorback sucker are capable of short bursts at speeds of 2 fps and <br /> <br />sustained swimming at velocities of 0.66 to 1 fps (Bestgen 1990). However, recent flume tests <br /> <br />performed by the Bureau of Reclamation indicate that the razorback sucker is capable of <br /> <br />swimming through higher velocities than previously thought, especially in ladders with cobbles <br /> <br />and boulders on the bottom similar to natural conditions (Mefford 2000b). Flume tests on <br /> <br />8 <br />