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<br />EXECUTIVE SUMMARY <br />Despite successful reproduction by razorback suckers (Xyrauchen texanus) in the middle <br />Green River, recruitment beyond the larval stage has not been recently observed. Bonytail (Gila <br />elegans) are essentially extirpated in the wild and nearly all bonytail present in the Green River <br />are hatchery-stocked fish. Floodplain wetlands may provide important rearing habitat for both <br />larval razorback sucker and bonytail. However, survival of razorback suckers in restored <br />floodplain habitat has not been observed since 1997, even when larvae were introduced directly <br />into floodplain sites. Large nonnative fish populations in floodplain habitats have likely <br />suppressed survival. The recent drought eliminated, or reset, nonnative fish populations in <br />i floodplain sites through complete dewatering. During an inundation period following a reset, <br />initial nonnative fish densities are low. This study's goal was to test if introduced larval <br />razorback sucker and bonytail could survive in the presence of reduced predation similar to that <br />~ present in a reset wetland. Two densities of razorback sucker and bonytail larvae were tested <br />using two 0.10 hectare enclosures with approximately equal numbers of nonnative fish. Survival <br />in these enclosures was observed and estimated at 0.67% and 0.37% for razorback sucker in the <br />~ low and high-density enclosures, and 1.7% and 1.3% for bonytail in the low and high-density <br />enclosures, respectively. However, even at these low survival rates over 3,000 razorback suckers <br />survived. Survival in the control enclosure (without nonnative fish) was 9.8% for razorback <br />~ sucker and 17.1 % for bonytail. <br />r <br />e <br />vii <br /> <br />