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H H ~ and green sunfish numbers increase fathead minnow numbers decline somewhat. ~ Some movement of non-native fish from the floodplain to the river did occur. However, ~ avast majority of non-native fish occupying the floodplain remained in the floodplain. • Increases of non-native fish in the river were only observed when draining events unrelated to removal of levees occurred. These increases did not persist between ~ seasons. ~ Native fish use of floodplain habitats was highly correlated with magnitude and • duration of the spring flood. Native fish captures were highest during years of high magnitude and long duration spring flows. Adult native fish species utilized floodplain ~ habitats during the connection period then returned the river during flow recession. Flannelmouth suckers and Colorado pikeminnows were the most abundant native • species caught in the floodplain. Razorback suckers were captured only occasionally. However, this is likely due to the extremely low numbers of razorback suckers in the ~ river. Unlike non-native species, native species did not utilize the floodplain for ~ reproduction. Instead YOY native fish use is dependent on passive drift into the • floodplain. Larval razorback, flannelmouth and bluhead suckers were caught drifting into floodplain sites. However, survival of YOY fish was not detected during the study. ~ For floodplains to aid in recovery of razorback suckers several events must ~ occur. First, razorback suckers must spawn successfully and have larvae entrained in ~ the floodplain. Second, larvae must survive and grow within the environment of the floodplain. Third, they must leave the floodplain and recruit into the river population. ~ Based on these life history events, a floodplain wetland that functions ideally in support ~ of razorback sucker recovery will have the following characteristics: 1) the site is ~ configured to maximize larval fish entrainment; 2) adequate cover to survive predation; • 3) high productivity; 4) low numbers of non-native fish; 5) adequate water quality to support fish year round; and 6) site is physically self sustaining. None of the floodplains ~ sampled fully meet these criteria. However, there are floodplain configurations that ~ support razorback sucker recovery better than others. Floodplains function in one of • three basic classifications: ~ 1) Deep Depression Classification - In this scenario larval razorback suckers are ~ entrained in a site and remain for one or more growing seasons. After one or • more growing seasons fish voluntarily leave the site during connection or could be removed mechanically. ~ 2) Terrace Classification -Under this scenario larval razorback suckers drift into ~ and utilize the site temporarily during high flow then reenter the river during flow ~ recession. 3) Managed Site Classification -These are sites with control structures that can ~ be managed as either depression or terraces. ~ There are both positive and negative features for each classification. However, • we believe depression sites (with or without control structures) that are configured to allow water flow through, will likely contribute the most to immediate recovery and long ~ term sustainability of razorback suckers. Therefore, the following recommendations ~ were made: xiii