7799

• UCREFRP Catalog Number: 7799
• Author: Modde, T. and D. Irving.
• Title: Conceptual Management Plan for Habitat Enhancement In Old Charley Wash.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

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28 razorback sucker adults have been collected during the spring in the Duchesne River, just below the

boundary Ouray National Wildlife Refuge. Most razorback sucker have been collected during the spring

months between late April and early June. In June 1993, suspected razorback sucker larvae were collected

at both the inlet and outlet of Old Charley Wash by Ed Wick (National Park Service). The only definitively

identified razorback sucker larva collected (Le. greater than 17 mm) during 1993 was at the Old Charley

Wash outlet.

ECOLOGICAL ROLE OF INUNDATED BOTTOMLANDS TO ENDANGERED FISH RECRUITMENT

Riverine wetlands are importance habitats believed necessary for recruitment of rare native species

in the Upper Colorado River Basin. A discussion of the energetics associated these bottomlands and its

importance to age 0 fish recruitment is provided in Appendix 1. The remainder of this section addresses

habitat restoration and how it relates to razorback sucker recruitment. Razorback sucker adUts are flexible

in their habitat use. Although these fish apparently evolved in large river systems, adults have survived well

in both lacustrine (Wallis 1951) and riverine (Tyus 1987) habitats. However, because few immature fish have

been captured, little is known of their habitat needs. Many suspected larval razorback sucker have been

collected in slack-water habitats over 100 km downstream from the Escalante spawning bar in the Middle

Green River in 1993 (Robert Muth and Daryl Snyder, Larval Fish Laboratory, Colorado State University;

Personal Communication). Suspected razorback sucker larvae were also collected commonly with light

traps in slack-water habitats from the Colorado River above Lake Powell in 1993 (Ed Wick, National Park

Service; Personal Communication). Because the lower length range of larvae collected in 1993 increased

downstream (Daryl Snyder, Larval Fish Laboratory, Colorado State University; Personal Communication),

it is possible that these larvae originated from the Escalante site as well as some other unknown site(s) in

the Lower Green River. Apparently, these fish drift at the velocity of the water mass to the sites in which

they are found. Despite, apparent successful reproduction, juvenile razorback suckers have only been

reported in the Upper Colorado River Basin three times in the past 40 years: eight fish between 90-115 mm