7157

• UCREFRP Catalog Number: 7157
• Author: Haynes, C. M., et al.
• Title: Larval Colorado Squawfish ‎(
• USFW Year: 1984
• Copyright Material: YES

March 1984

Haynes et al.-Larval Colorado Squawfish

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FIG. I.-Distribution of Colorado squawfish in Colorado and adjacent portions of Utah (after
Tyus et aI., 1982). Species range indicated by heavy stipple; areas where larvae were collected in
1979-1981 indicated by light stipple.

of shallow low-velocity habitat and, therefore, w~s unequal in different localities. For example,
the White River was higher in gradient than the lower sections of the Colorado or Yampa rivers
and had relatively fewer suitable sampling areas per kilometer.
In the laboratory, squawfish larvae were identified using descriptions and standard morphomet-
ric and meristic analytical techniques (Hubbs, 19411; Snyder, 1981). In addition, a known-age
larval series, which had been reared at Willow Beach National Fish Hatchery, Arizona, and
which were the progeny of Upper Colorado River parents was used for comparison. Larvae were
counted, measured to the nearest 0.5 mm total length (TL), and stored in 11% buffered formalin at
the Nongame Research Station, Colorado Division of Wildlife, Fort Collins, and the Larval
Fishes Laboratory, Colorado State University, Fort Collins.