7025

• UCREFRP Catalog Number: 7025
• Author: Hawkins, J. A. and T. P. Nesler.
• Title: Nonnative Fishes in the Upper Colorado River Basin
• USFW Year: 1991.
• USFW - Doc Type: An Issue Paper.
• Copyright Material: YES

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Habitat management

-Habitat improvement favoring maintenance of native species populations.
-Expand habitat availability through passage and increased access to available habitat
-Implement water management strategies to reduce the success of some introduced species
and increase the success of native species.
-Flow alteration (spring peaks, more natural hydrograph) to benefit natives, hinder
nonnatives.
-Habitat management with flows.
-Provide more favorable flow regimes and habitat
-Manage for pristine habitat conditions.
-Provide best habitat conditions through maintenance of natural flow regime to benefit
native fishes versus nonnative fishes.
-Site specific flow and habitat management practices that promote natives and eliminate or
reduce nonnatives.
-Determine flows that benefit native species over nonnatives.
-Flow regimes from major dams need to give every advantage to native fishes.
-Return the system to a natural flow regime.
-Management activities (including management of flows to increase the magnitude and
frequency of high spring flows, and increase availability of optimal spawning habitat
like flooded lowlands for razorback sucker) to enhance reproductive success of
endangered fish maybe the best strategy in lieu of a means to eliminate introduced
fish.
-Creation of artificial habitats/channels where success (abundance and reproduction) of
target species can be monitored.
-Water rights acquisition.
-Better water conservation.

Several respondents reiterated the opinion that better flow and habitat management would
reduce the relative impact of nonnative species by creating an environment more favorable
to the survival capabilities of native species.

Control of nonnative fishes

-Periodic and perpetual removal of nonnatives by some means yet undiscovered
-Periodic electrofishing to remove introduced species limited to habitats of small size.
-Provide nonnative fish control during spawning and rearing in select habitats.
-Intense assistance during reproductive period for razorback sucker.
-Identify problematic species first, then determine if it is possible to control them.
-Target key habitats used by introduced species as refugia.
-Selective renovation or harvest in stream reaches known to concentrate nonnatives (below
diversions, for example).
-Increase harvest (sport and commercial) of nonnatives.
-Stop further stocking of nonnatives (present and new species).