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

depletions, continues to support one of the highest proportions of native flannelmouth suckers
mus latipinnis) and bluehead suckers (c. discobolus) of any river in the basin (Holden
espite the presence of 13 species of nonnative fishes, reproducing and self-sustaining
populations of native species persist, except for Colorado pikeminnow and razorback sucker.
The San Juan River Basin Recovery Implementation Program (SJRIP) is a similar
program to the UCRRP and was established in 1991, to conserve populations of Colorado
pikeminnow and razorback sucker in the San Juan River Basin, while proceeding with water
development in co . ce with federal and state laws, interstate compacts, decrees, and federal
trust responsibilitie

3.0 THREATS TO THE SPECIES

Threats to the four endangered fishes were not fully known and understood at the time
that the species were listed. The principal perceived threats when Colorado pikeminnow and
humpback chub were designated as "end gered" in 1967 were dams and nonnative fishes.
When the bonytail and the razorback su were listed in 1980 and 1991, the threats were better
understood, but the manner in which s were affecting the fish was poorly understood,
and actions to minimize or remove those threats were just being developed. Primary threats to
the four endangered fish species of the Colorado River Basin include streamflow depletion and
regulation, physical and chemical habitat modifications, hybridization, and nonnative fish
species. These threat categories fall within the five listing factors (see Section 1.3), as described
in the following sections. Site-specific management actions .. mize or remove these threats
are provided in section 5.0.
3.1 The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
3.1.1 Streamflow Modification
Maintenance of streamflow is important to the ecological integrity of large western rivers
(Collier et at. 1996, Poffet at. 1997, Schmidt et al' 1998). Life histories of many
including fish, are often specifically timed to flow magnitude and timing, and disrupti

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