7406

• UCREFRP Catalog Number: 7406
• Author: Bestgen, K. R.
• Title: Status Review of the Razorback Sucker,
• USFW Year: 1990.
• Copyright Material: NO

Lower Colorado River Basin
Primary drainage units of the LCRB are the mainstream
Colorado River and four major tributaries, the Little Colorado,
Virgin, Bill Williams, and Gila rivers. Razorback suckers in the
LCRB historically occurred in the mainstream Colorado River and
the Gila River drainage.
Colorado River--Historic distribution of razorback suckers
in the mainstream Colorado River (LCRB) extended from the
Colorado River delta in Mexico upstream to present-day Lake
Powell. It was most abundant downstream of present-day Lake
Mead, and particularly so around Yuma (Gilbert and Scofield
1898). Few records exist for razorback sucker in Grand and
Marble canyons, Arizona, (Smith 1959), and lack of extensive
surveys (Miller 1946) made historic estimates of abundance in
that reach difficult. Razorback suckers may have been
historically uncommon in turbulent canyon reaches of the LCRB.
Razorback suckers in the Green River (UCRB) are typically found
in calm, "flatwater" river reaches, not in turbulent canyons
(Tyus 1987, Lanigan and Tyus 1989).
Archeological remains of razorback suckers were common in
__.___ the Salton Sea area, and a reproducing population apparently
existed there in primeval times (Minckley 1983, Minckley et al.
in press). Increasing water salinity due to evaporation rendered
habitat for freshwater fishes marginal after 1929 and razorback
suckers disappeared (Evermann 1916, Coleman 1929).
8