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184 WESTERN NORTH AMERICAN NATURALIST <br />Cottonwood <br />Cove Marina <br />Tequila <br />Cove <br />N <br />5 Females-12 sightings <br />4 Males-12 sightings <br />0 5 km <br />I <br />na Cove <br />7 sightings <br />sightings <br />[Volume 60 <br />Fig. 2. Location and movements of male and female Xyrauchen texanus in association with major spawning areas dur- <br />ing peak spawning (1-28 February 1995, 1996) in Lake Mohave, Arizona-Nevada. <br />(depths > 30 m). Fish body temperatures ranged <br />between 12° and 28°C, with summer averages <br />ranging from 18° to 22°C, which was similar <br />to thermal preferences reported by Bulkley <br />and Pimentel (1983). Hourly data indicated <br />fish moved vertically in the water column, but <br />we found no correlations for depth with time <br />of day. <br />Vertical temperature profiles (n = 107) were <br />taken from May through November 1995 to <br />correlate body temperature with depth. Fish <br />ranged to depths >30 in but typically were <br />found near 9 in (x = 9.1 m; Fig. 3). Average <br />fish depths changed with season, suggesting <br />fish may regulate body temperature during <br />reservoir stratification (Fig. 3). Fish were <br />found nearer the surface during spring and <br />autumn and deeper during midsummer. <br />DISCUSSION <br />Lake Mohave scarcely represents what many <br />would consider pristine X. texanus habitat. <br />However, it is noteworthy that 3 of 4 remain- <br />ing wild populations (>100 individuals) are <br />found in reservoirs (Minckley et al. 1991, <br />Holden et al. 1997, Modde and Wick 1997). <br />Investigators who have conducted research in <br />riverine environments have been challenged <br />February 1995 <br />February 1996