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<br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />The timing of flows through regulated water releases from dams is <br />important to ensure that (1) flows and substrate in the main channel are <br />suitable for razorback sucker spawning and (2) flows will inundate <br />floodplains so that larval razorbacks have access to productive <br />floodplains during their critical period. <br /> <br />Removal of levees that are located on the lowest floodplain terraces <br />(public property or acquired private property) is an alternative way to <br />reconnect mainstem and tributary rivers with productive floodplain <br />habitats. Such removal should be done on properties that can be easily <br />reconnected with the main channel and inundated with existing or slightly <br />enhanced streamflows. <br /> <br />Since the existing floodplain terraces were deposited when natural <br />streamflows were high, floodplain terraces in prime areas that can be <br />easily inundation are limited. It may be necessary to excavate existing <br />terraces so that present and/o~ restored streamflow regimes can inundate <br />floodplains where levees are breached. <br /> <br />3. <br /> <br />The river discharge necessary to provide an adequate frequency of <br />inundation of floodplain habitats should be initially made on an annual <br />basis or as often as possible. However, long-lived fish species that <br />have exhibited strong year-class strength such as the razorback sucker or <br />Colorado squawfish may only require inundation of floodplains in 1 out of <br />5 to 10 years to maintain self-sustaining populations after populations <br />have been reestablished. <br /> <br />4. <br /> <br />The use of depression ponds in the floodplain should be considered as <br />prime habitats for rearing wild razorback sucker larvae or captive-reared <br />razorback suckers. Shallow floodplain depressions may require excavation <br />to increase the water depth to prevent winterkill if the razorback <br />suckers are reared to a larger size. <br /> <br />Excellent growth of razorback suckers in floodplain habitats has been <br />demonstrated in the Upper and Lower Basins of the Colorado River system. <br />Floodplain depression ponds provide habitat where razorback suckers can <br />reach a size when predation by nonnative fish species would be <br />considerably reduced as razorbacks gain access to the river on subsequent <br />high streamflows. <br /> <br />If frequency and duration of flooding through managed streamflows cannot <br />be restored, then floodplain depressions may be the only course of action <br />left for maintaining razorback sucker stocks from extinction until <br />solutions are found for recovery. <br /> <br />5. <br /> <br />Design and conduct appropriate field experiments as Recovery Program <br />funds are available to determine the control method(s) that will be <br />adequate to reduce or manage selected nonnative fish species where the <br />floodplain has been reconnected with the main channel. <br /> <br />Control of nonnative fishes on a largescale basis in a large river system <br />is not practical based on the published literature. Therefore, nonnative <br />fish management should be emphasized in river reaches that are <br />immediately upstream or downstream of floodplain habitats that are <br />already connected or are reconnected to the river. <br /> <br />6. <br /> <br />Continue reintroduction stocking of captive-reared razorback suckers in <br />the upper Colorado River and augmentation stocking in the middle Green <br />River. <br /> <br />Floodplain ponds in the vicinity of suitable spawning bars in adjacent <br />rivers can be used to rear wild razorback sucker larvae or captive-reared <br /> <br />5 <br />