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<br />This study demonstrated that larval razorback sucker survival could occur following a <br />reset of nonnative fish populations. However, this survival occurred in a controlled environment <br />and the following factors should be considered. <br />1. Although the nonnative fish numbers introduced into the enclosures were based <br />on actual data, they still represent an estimate of what actually may occur in <br />different years. <br />2. Fish were contained in a relatively small area (0.10 hectares). ~ <br />Enclosures were used for two reasons. First, enclosures increase sampling efficiency. <br />Second, enclosures allow for testing larval razorback sucker survival at different densities in the <br />same floodplain. The densities of larval razorback suckers used for this study are likely higher ~ <br />than densities that would result from natural reproduction in the river and entrainment in the <br />floodplain. Prior to this study, it was not known if razorback suckers could survive in the face of <br />intense predation at any larval razorback sucker density. ~ <br />Survival rates offish introduced were nearly identical in both high and low-density <br />enclosures, and were predictably much lower than the control enclosure. <br />Based on the number of non-native fish observed in the first year of the Levee Removal ~ <br />study, this study demonstrated that the floodplain `reset' approach could work allowing <br />recruitment of naturally spawned endangered fish to significantly contribute to recovery. <br />However, several questions remain before this concept can be effectively implemented into ~ <br />recovery actions. These questions include: what factors most affect survival, (i.e., density of <br />larvae, density of predators, or physical characteristics of floodplains)? Most likely all of these <br />factors have an effect. <br />Increasing the number of spawning adults, and/or the number of spawning sites may <br />enhance densities of larvae. Predator density may be managed through the frequency of flood <br />plain reset, which is a function of flows and levee breach configuration (Birchell et al. 2002). <br />18 <br /> <br /> <br /> <br />