9383

• UCREFRP Catalog Number: 9383
• Author: SWCA, I.
• Title: Recovery Goals for the four Colorado River Endangered Fish Species.
• USFW Year: 2000.
• USFW - Doc Type: Logan.
• Copyright Material: NO

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

channel catfish (Ictalurus punctatus), small mouth bass (Micropterus dolomeiui), largemouth bass
erus salmoides), bluegill (Lepomis macrochirus), green sunfish (Lepomis cyanellus),
ar sunfish (Jonez and Sumner 1954, Bozek et al. 1984, Langhorst 1989, Marsh and
Langhorst 1988, Marsh 1999, Marsh and Brooks 1989). Lentsch et al. (1996) identified six
species of nonnative fishes as existing threats to native species, including red shiner (Cyprinella
lutrensis), common carp, sand shiner (Notropis stramineus), fathead minnow (Pimephales
promelas), channel catfish, and green sunfish. Small forms, such as red shiners, are known
e fish (Rupert et al. 1993). Large predators, such as walleye
(Stizostedion vitre d northern pike (Esox lucius) also pose a threat to subadults and adults
(Tyus and Beard 1
A Strategic Plan for Nonnative Fish Control was developed for the upper Colorado River
Basin (Tyus and Saunders 1996) and implemented by the Upper Colorado River Basin Recovery
Program in 1997. The results of the control program are inconclusive as to the beneficial effects
for native fishes.
Three actions are also identified duce the threat of nonnative fishes; high spring
flows, nonnative fish control strategie ocking agreements. There is documented evidence
that high flows temporarily disadvantage nonnative fishes in several ways, including
displacement from sheltered habitats, disruption of spawning activities, increased mortality in
high mainstem currents, and physical downstream transport of individuals (Valdez 1990,
Hoffnagle et al. 1999). Even a short-term decline in nonnative fishes could allow increased
survival and recruitment of native forms. All flow recomm . ns packages include the
provision of the greatest frequency of high flows possible, w will provide these unsuitable
conditions for many nonnative fishes, and at least temporarily reduce numbers of these predators
and competitors.
The upper Colorado River basin states recently entered into an agreement which provides
guidance on releases of nonnative species. This agreement prohibits releases of nonnative fishes
within the 100-year flood plain of the river. The agreement provides security against state or
federal endorsed programs introducing new species into the system or increasing die ers or
distribution of existing species. A Memorandum of Agreement implementing these

16