7864

• UCREFRP Catalog Number: 7864
• Author: Modde, T. and E. J. Wick.
• Title: Investigations Of Razorback Sucker Distribution, Movements And Habitats Used During Spring In The Green River, Utah.
• USFW Year: 1997.
• USFW - Doc Type: Recovery Program Project No. 49,
• Copyright Material: NO

Experiments to evaluate the impacts of red shiner competition with larval and
early juvenile razorback sucker provided no insight into competitive interactions.
However, the rapid predation of larval razorback sucker by red shiner corroborated the
suggestion by Ruppert et al. (1993) that larvae of endangered fishes are vulnerable.to
predation by this minnow. Because razorback sucker are the first larval fish to appear
in the spring, the potential for predation by red shiners in absence of other prey sources
may represent an obstacle for recruitment if red shiners are abundant in floodplain
habitat.

Although floodplain habitat has been linked to the early life history and
recruitment of razorback sucker in the middle Green River, little is known of the specific
relationship of wetlands use by razorback sucker. Nutrients in floodplain habitat are
much greater than in main-channel habitat (Junk et al. 1989) and contribute to greater
production in both in- and off-channel habitats. Mabey (1993) reported that
invertebrate production in Old Charley Wash was approximately an order of magnitude
greater than observed in either backwater or main channel habitats. Despite the well
established trend of high production in wetland habitat, timing and distribution of
invertebrate production and use by native fishes in this habitat of the middle Green
River are not well understood.

Irving and Burdick (1995) stratified the floodplain of the middle Green River as
terrace (not retaining water as river elevation receded following spring peak flows) and
depression (retaining water following decline in river elevation in the spring) wetlands
and described their area and distribution. Water retention is a major factor separating
the functional characteristics of these wetland types. Their importance to the early life
history of razorback sucker mayor may not be equivalent.. The quality or relative
importance of these two floodplain habitat types to endangered fish recovery is yet to
be defined and may have an important influence on flow management strategies.

CHAPTER THREE: Inundation of Old Charley Wash

METHODS

The wetland habitat availability portion of this study was narrowly focused on
determination of flows necessary to inundate Old Charley Wash. A surface elevation
gage was installed in the outlet to Old Charley Wash and data was collected during the
high water year of 1993. Surface elevations were correlated with the flows at the
Jensen USGS gage and then used, together with 0.3 m topographic maps, to
determine the flows necessary to inundate Old Charley Wash. Flows necessary to
maintain flooding in Old Charley Wash were determined using the outlet gage data.

RESULTS

Surface elevation contours of Old Charley Wash, Le. Wood's Bottom (0.3 m,
contour maps), indicate that the lowest point along the dikes of the wetland are located
on the downstream portion of the wetland at an elevation between 1418.8 and 1419.1
meters above mean sea level (mamsl) (Modde and Irving 1994). Based on the surface
elevation data collected from the Old Charley Wash outlet gage in 1993, water began
inundating the wetland from the river at a discharge between 405 m3/s and 455 m3/s
(Figure 7).

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