Colorado River cutthroat
trout (Oncorhynchus clarki pleuriticus):
Historic Range:
The most spectacular of the colorful cutthroat trout and one of the
most beautiful fish in North America, the Colorado River cutthroat trout
historically occurred in most cool water habitats of the Colorado River
drainage in Colorado, southern Wyoming, eastern Utah, and extreme northwestern
New Mexico and northeastern Arizona.
Habitat requirements:
Like most members of the trout family, Colorado River cutthroat trout
require clear, cold water, naturally-fluctuating flows, low levels of
fine sediment in channel bottoms, well-distributed pools, stable streambanks,
and abundant stream cover.
Current population status:
These trout are extremely imperiled. The Colorado River cutthroat trout
currently occupy approximately five percent of its historic range, primarily
in isolated, small headwater streams. Conservation populations--those
with a high degree of genetic integrity--are estimated to only occupy
less than one percent of these trout's historic range, as documented
in the Western Native Trout Campaign's report: Imperiled
Western Trout and the Importance of Roadless Areas. The same report
estimates that about 62% of the remaining conservation populations of
these trout are associated with roadless areas, clearly indicating that
the full protection of roadless areas is vital to the persistence of
these spectacular, and highly endangered, native trout.
Threats to continued persistence:
The severe contraction in the Colorado River cutthroat trout's range
was primarily caused by the stocking and spread of non-native trout,
and habitat loss due to livestock grazing, water diversion, logging,
roads, mining and other factors, which degrade stream conditions required
by these trout.
Listing Status (as of 5/02):
The Center for Biological Diversity and a coalition of groups filed
a petition to list the Colorado River cutthroat trout as endangered
in December, 1999. In response to lack of action on the part of the
U.S. Fish and Wildlife Service, the Center and other groups filed suit
in January, 2001 to force the agency to process the petition. The court
has failed to make a decision on the case and in March, 2002, we filed
a new motion to bring it to the courts attention.
