9420

• UCREFRP Catalog Number: 9420
• Author: Maddux, H. R., J. A. Mizzi, S. J. Werdon and L. A. Fitzpatrick.
• Title: Overview of the Proposed Critical Habitat for the Endangered and Threatened fishes of the Virgin River Basin.
• USFW Year: 1995.
• USFW - Doc Type: Salt Lake City.
• Copyright Material: NO

Loss of inundated floodplain habitats in the Missouri River Basin has been associated with a
concomitant reduction of as much as 98 percent of fish biomass (Karr and Schlosser 1978).
Inundation of floodplain habitats during spring flows provides areas with warmer water
temperatures, low velocity resting habitat, and cover from predation in flooded terrestrial
vegetaxion. Recent studies in the Colorado River system have shown -that the life histories
and welfare of native riverine fishes is linked with the maintenance of a natural or historic
flow regimen (i.e., a hydrological pattern of high spring and low autumn-winter flows that
vary in magnitude and duration depending on annual precipitation patterns and runoff from
snowmelt) (Tyus and Karp 1989, 1990). It has been predicted that stream regulation that
results in loss of flooding will result in extirpation of many of the, native fish species in the
Colorado River system (Hinckley and Meffe 1987).
16