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r I <br />ABSTRACT <br />Razorback sucker (Xyrauchen texanus) larvae were studied in Lake <br />Mohave, Arizona-Nevada, during 1985. Adult suckers spawned from early <br />January until late April and larvae were abundant from early February <br />until mid-April. Most larvae were collected from shoreline areas with <br />only one taken from open waters. Dispersal patterns of larvae from <br />major spawning areas could not be determined. Average total length (TL) <br />of larvae from Lake Mohave was 10.6 mm and showed no evidence of <br />increasing through the period. Larvae reared in both a predator-free, <br />isolated backwater and in cages placed in Lake,Mohave attained maximum <br />lengths of >20 mm. Survival and growth in Lake Mohave water thus are <br />not precluded. Larvae (<12 mm)-fed primarily, upon zooplankton; <br />cladocerans (Bosmina, Daphnia), copepods, and rotifers were dominant <br />items both in larval diets and in the lake. Larger larvae (>12 mm) had <br />a more diverse diet which included larger foods (e.g. chironomid <br />larvae). All larvae selected Daphnia which were about one-half the <br />average size of those available. Green sunfish (Lepomis cyanellus) ate <br />razorback sucker larvae, but rates remain unquantified and impact of <br />predation on sucker recruitment is not known. Abundant sucker larvae <br />reared in a predator free backwater disappeared within 4 weeks after <br />invasion of the system by other fishes, including green sunfish. Fate <br />of larval razorback in Lake Mohave may be depredation, down-reservoir <br />transport out of the system, or both.