Distribution, movements, and habitat use of 10 wild adult razorback suckers (Xyrauchen texanus) were examined in Lake Mohave, Arizona-Nevada, from November 1994 through July 1997. Movement rates (0.00-17.35 km d⁻¹) and ranges (x̄ = 39 km) were similar to those for riverine populations. All study fish returned to spawning sites used in previous years, but they also visited other spawning areas. Spawning females were significantly (P = 0.031) more active than males (480 vs. 87 m d⁻¹) and moved substantial distances between spawning sites during peak reproduction (1-28 February). Fish became most active (m d⁻¹, km month⁻¹) after spawning and moved to areas known to support higher algal production. Fish were typically within 50 m (F < 0.001) of shore and at average depths between 3.1 and 16.8 m (range 0.2 to > 30.0 m). Adults were detected throughout the available thermal gradient (12°-30°C), but during summer typically had body temperatures between 18° and 22°C. Vertical movements within the water column showed no correlation with depth or time of day, but seasonal shifts suggest fish may regulate body temperature by seeking specific temperatures during reservoir stratification.
