3201

• UCREFRP Catalog Number: 3201
• Author: Osmundson, D. B.
• Title: Growth and Survival of Colorado Squawfish ‎(Ptychocheilus lucius)‎ Stocked in Riverside Ponds, With Reference To Largemouth Bass ‎(Micropterus salmoides)‎ Predation
• USFW Year: 1986
• USFW - Doc Type: \
• Copyright Material: NO

1
INTRODUCTION
Background and Literature
General
The Colorado squawfish (Ptychocheilus lucius) is a
piscivorous cyprinid endemic to the Colorado River system.
Capable of attaining lengths greater than 150 cm, it is the
largest minnow in North America. Before the turn of the
century, squawfish were very abundant throughout most of
the Colorado River basin (Jordan and Evermann 1902, Miller
1961). An Arizona newspaper in 1896 reported during the
annual spawning migration that Phoenix.residents armed
with pitchforks were driving to the Salt River to load
their wagons with squawfish (Avery 1974). Other reports
tell of ranchers pitchforking squawfish out of irrigation
canals by the hundreds and casting them on the bank to be
used as fertilizer (Miller 1961, Ono et al. 1983).
Today, P. lucius is considered extinct in the lower
Colorado River basin from Glen Canyon Dam to the Gulf of
California. In the upper basin it is rare, occurring
mainly in the Colorado, Green, Yampa, and White rivers
(Fig. 1). The decline of the species has been attributed

to several factors: dewatering, dams and reservoirs, alter-
ation of stream flow and stream morphology, changes in
water quality, and the introduction of exotic species
(Miller 1961, La Rivers 1962, Minckley 1973, Seethaler