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Last modified
7/14/2009 5:02:35 PM
Creation date
5/17/2009 10:51:31 PM
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UCREFRP
UCREFRP Catalog Number
9410
Author
Wydoski, R. S. and E. J. Wick.
Title
Ecological Value of Floodplain Habitats to Razorback Suckers in the Upper Colorado River Basin.
USFW Year
1998.
USFW - Doc Type
Denver.
Copyright Material
NO
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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 />
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