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34 <br />Douglas [1952] documented spawning in Lake Havasu in March 1950. <br />Razorback suckers moved into shallow coves of the lake with water <br />depths ranging from 25 to 50 cm when surface water temperatures <br />were 14 to 18 C. Females, accompanied by two to six males, cruised <br />over the bottom of the cove in small circles. Males remained in <br />close proximity to responsive females as they swam over the bottom <br />of the cove. On occasion, the fish settled to the bottom, vibrating <br />their bodies rapidly. Gametes were presumably emitted at this time, <br />but DougZas' vision was obscured by silt disturbed by the spawning <br />fish. <br />Jonez and Summer [1954] observed spawning razorback suckers in <br />Lake Mead between March 1 and April 15, 1953. They described an <br />extensive shoreward movement during the spawning season with the <br />greatest concentrations of razorback suckers occurring in the <br />vicinity of river mouths. Water temperatures ranged from 12 to 18 C <br />during this period. Spawning activity appeared widespread along <br />gravel shores at depths of 0.6 to 5 m. Actions of spawning fish <br />were similar to those described by Douglas [1952]. <br />Jonez and Summer [1954] reported what they identified as small <br />razorback suckers below Davis Dam in 1950 and felt predation of the <br />freshly spawned eggs would limit reproductive success in Lake Mojave. <br />More recently, spawning activity by razorback suckers was reported <br />in these same reservoirs, but the young were not found, indicating <br />poor reproductive success [MinckZery, 1973]. Some successful <br />reproduction may have occurred since the reservoirs were impounded, <br />because adults are still found. However, long-lived species could <br />create an illusion of successful reproduction.