8288

• UCREFRP Catalog Number: 8288
• Author: Chart, T. E. and L. Lentsch.
• Title: Reproduction and Recruitment of Gila Spp. and Colorado Squawfish ‎(Ptychocheilus lucius)‎ in the Middle Green River 1992-1996\
• USFW Year: 1997.
• Copyright Material: NO

INTRODUCTION
Desolation and Gray (peso/Gray) Canyons hold the strongest concentration of native Gila spp. in
the Green River sub-basin. These canyons were first sampled in 1967-1971, when distributions
and abundances of mainstream fishes were determined throughout the middle and upper Colorado
River Basin (Holden and Stahialcer 1975). The U.S. Fish and Wildlife Service (USFWS )
returned to Desolation approximately ten years later as part of their Green River Investigations
(Tyus et al. 1982}. The Utah Division of Wildlife Resources (iJDWR) has monitored the
Deso/Gray fish populations annually since 1985 (tJDWR 1995). Beginning in 1994 the UDWR
initiated the present study to determine the relationship between Green River flows and Colorado
squawfish and native chub reproduction and recruitment. This study, a component of the Flaming
Gorge Research Program is composed of two distinct but related efforts. The first and more
intensive aspect of the study is the nursery habitat sampling (PART A). The second. is a
continuation of the long term fish community monitoring program and investigations into
Colorado squawfish spawning sites other than the Three Fords site; those objectives are the
subject of this report (PART B).
Although Desolation Canyon sampling was not part of the Flaming Gorge Studies until 1994, data
has been included since 1992 and prior to that in some instances for the purposes of long term
monitoring.
STUDY AREA
Deso/Gray Canyons occur south of the Umta Basin, UT beginning at Sand Wash (RM 216: 216
river miles upstream of the Green and Colorado rivers confluence) and ending abruptly 12 miles
upstream of the town of Green River, Utah (RM 120) (Figure 1). The contiguous canyons of
Desolation and Gray are sharply different. Desolation Canyon (RM 216 -157) is characterized by
a deep canyon derived from the Wasatch and Green River formations. The stretch of river
between Sand Wash and Cedar Ridge Canyon (RM 185) is primarily slow flat water. The canyon
becomes more confined and gradient steepens from this point down river. The deepest point of
Desolation Canyon is deeper than the Bright Angel Trail of the Grand Canyon with a vertical rise
of more than 1 S 15 m from the river to the Tavaputs Plateau. Gray Canyon (RM 157 -132)
DRAFT ~ 1