9346

• UCREFRP Catalog Number: 9346
• Author: Seethaler, K.
• Title: Life History and Ecology of the Colorado Squawfish ‎(Ptychocheilus lucius)‎ in the Upper Colorado River Basin.
• USFW Year: 1978.
• USFW - Doc Type: Utah State University,
• Copyright Material: NO

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and the phenomenon of its endangered status. The main objective was to
synthesize this knowledge into a single volume to aid in effective man-
agement decisions.
An exhaustive chapter on historical and present distribution of the
Colorado squawfish documents every known sighting of this species in all
rivers and tributaries in the Colorado River system since 1825. A wide-
ranging piscivore, this species frequents all habitat types in the river
except the cold headwaters, though it was most often found in eddies,
backwaters, and deep holes.
Field observations were made primarily in Dinosaur National
Monument and adjacent areas of the upper Green and Yampa rivers, and at
Grand Junction on the Colorado River main stem. Trammel nets, seines,
and occasionally electrofishing were used to capture fish.
The Colorado squawfish, one of four species of the genus
Ptychocheilus, evolved with the Colorado River system. Attesting to its
reputation as a food and sport fish, it has locally acquired such names
as lIsalmon,lI lIwhitefish,lI and lIpike.lI In fact, the species is the
largest cyprinid in North America, a family which arrived in this con-
tinent about the time of the Miocene epoch.
Although captured from two widely separated geographical localities
in the Colorado and Green Rivers, the species apparently consists of a
single population. Analysis of electrophoretic and meristic data failed
to show any intraspecific differences between fish captured from these
two locations.
Positive identification of larval and juvenile fish often presents
a problem to collectors. Because there is a need for adequate descrip-
tions of the young, a series of 15 detailed drawings was made using a

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