8002

• UCREFRP Catalog Number: 8002
• Author: Bozek, M. A., L. J. Paulson and J. E. Deacon.
• Title: Factors Affecting Reproductive Success of Bontytail Chubs and Razorback Suckers in Lake Mohave.
• USFW Year: 1984.
• USFW - Doc Type: Technical Report No. 12,
• Copyright Material: NO

1.0 INTRODUCTION
1.1 Status of Razorback Suckers and Bonytail Chubs in the Colorado
River
Razorback suckers (Xyrauchen texanus) and bonytail chubs
(Gila elegans) were once widespread throughout the Colorado River
system. The ranges and populations of these native species and others
have declined in the past 50 years (Miller 1961; Minckley and Deacon
1968; Johnson and Rinne 1982; Minckley 1983). Bonytail chubs appear to
be extremely rare and possibly nearing extinction in the Upper Colorado
River Basin. The razorback sucker is widely distributed in the upper
river but is considered rare throughout most of that range (Vanicek et
al. 1970; Holden and Stalnaker 1975 a,b; Seethaler 1979; McAda and
Wydoski 1980; Lanigan and Berry 1981; Valdez 1982; Tyus 1982) and is
also rare in the Grand Canyon (Suttkus and Clemmer 1979). Razorback
suckers are abundant only in a few habitats in the upper river. They
congregate and spawn over a cobble bar in an eddy at the mouth of the
Yampa River (Holden and Stalnaker 1975; McAda and Wydoski 1980). Tyus
(1982) collected a large number of razorback suckers in a similar
habitat downstream from that location at the mouth of Ashley Creek. The
Walter Walker Wildlife Refuge and Clifton Pond are also sites where
razorback suckers are known to congregate for spawning (McAda and
Wydoski 1980; Seethaler 1979; Valdez 1982). Recent specimens collected
from the upper river all have been large adults.
Bonytail chubs apparently were abundant throughout the lower
Colorado River early in this century. Locals believed bonytail chubs
once were themost abundant fish in the river reach from Needles to
Yuma. Bonytail chubs and razorback suckers were also common in Lake Mead