9410

• 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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disrupted nutrient cycling through the continuum process. Although the
flood pulse process was an integral part of the natural river-floodplain
ecosystem, it is even more important for productivity in the present
fragmented ecosystem.

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Reduction of historic peak streamflows and extensive levees prevent the
connectivity in this river-floodplain ecosystem. Reconnection of the
floodplain with Upper Basin rivers will reestablish some of the lost
integrity and productivity of the river-floodplain ecosystem.

16. The long-lived and highly fecund razorback suckers may not require
successful recruitment annually to develop self-sustaining populations.
The frequency of successful recruitment to produce self-sustaining
populations of razorback suckers is unknown but can be determined through
field evaluations. It is possible that successful recruitment every five
to ten years may be sufficient to naturally maintain the razorback sucker
since this species lives to 44 years or possibly longer. However, it
would be desirable to have recruitment every year or as often as possible
until target Recovery Program objectives are achieved.

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Recommendations:

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Continue acquisition and enhancement/restoration of floodplain habitats
in the Upper Colorado River Basin because reconnect ion of rivers with
floodplain habitats will improve the productivity of the ecosystem for
zooplankton and benthic invertebrates required for survival by the early
life stages of the razorback sucker.

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ACquisition with the intent of preserving existing floodplains that are
still functional will help maintain the existing integrity of the river-
floodplain ecosystem.

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Reconnection of floodplain habitats appears to be critical to increase
larval razorback sucker survival during their critical period so self-
sustaining populations (i.e., recovery) can be developed. Also, adult
razorback suckers may benefit from feeding on zooplankton and benthic
invertebrates in the productive floodplain habitats to regain their body
condition after spawning. Mature razorbacks may spawn in floodplain
habitats that would benefit natural reproduction when streamflows at
normal river sites are unsuitable for spawning.

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Any enhancement or restoration endeavors must be made through experiments
that are thoroughly evaluated using a systems approach that incorporates
adaptive management processes. Areas that are enhanced/restored should
be thoroughly evaluated to determine the responses of the endangered and
nonnative fishes to such efforts and refinements made as necessary to
achieve desired goals and objectives.

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:2 .

Continue to focus on levee removal to reconnect floodplains with Upper
Basin rivers and consider excavating present floodplain terraces that are
higher in elevation than present streambanks.

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Regulated streamflows can be managed to inundate floodplain habitats for
a longer period of time to increase survival of razorback sucker larvae.
Several large-river ecologists emphasize the importance of mimicking
historic hydrographs to reestablish integrity of river-floodplain
ecosystems. Field experiments to evaluate increasing streamflows will
have to deal with private land issues and streamflow variability will
have to be increased incrementally to minimize flood hazards to private
agricultural or occupied floodplain areas.

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