7418

• UCREFRP Catalog Number: 7418
• Author: Tyus, H. M. and C. A. Karp.
• Title: Stream Flow Needs of Rare and Endangered Fishes, Yampa River, Colorado.
• USFW Year: 1988.
• USFW - Doc Type: Vernal, Utah.
• Copyright Material: NO

1985) suggests that these non-native predators may be competing with and/or
preying on Colorado squawfish. Although Pimental et al. (19$5) found that

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Colorado squawfish did not prefer channel catfish as prey, incidence of
channel catfish lodged in throats of adult Colorado squawfish (McAda 1983,
Pimental et a1. 1985, Wick et aI. 1985) suggests that these introduced fish
may adversely affect survival of Colorado squawfish.
Captures of adult Colorado squawfish with lures and bait in Yampa River
(FWS unpublished data, Salle 1980) su~~ests that large individuals are
susceptible to angling pressure. FWS records (Vernal, UT) show that in some
years, as much as ZO% of the tagged Colorado squawfish are angler-caught.
Martinez (1986) has also noted several instances of incidental takes in the
White River, Increases in fis'ning pressure and incidental ta'ces could
significantly impact Colorado squawfish abundance.
Reproductive success of Colorado squawfish is dependent upon a number of
interdependent factors including number of spawning adults (particularly
numbers of ripe females), river dischar~~, ~N~.liment load, temperature, and
photoperiod. Loss of successful reproduction in one or more years could
result in significant declines of Colorado squawfish, and aid proliferation of
non-native competitors.
Because Colorado squawfish eggs are ad'nesive and attach to substrate
surfaces, availability of cleaned cobble and boulder surfaces in spawning
areas may be limiting, if spring/early summer scouring action from high
sediment loads is curtailed by a reduction in spring peak flows. A gradual
decrease in summer flows aids in preventing siltation of cobble bars, and this
flushing flow is potentially Limiting.
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