7327

• UCREFRP Catalog Number: 7327
• Author: Johnson, J. E.
• Title: Status of Endangered and Threatened Fish Species in Colorado.
• USFW Year: 1976.
• USFW - Doc Type: T/N 280,
• Copyright Material: NO

' present taxonomic problems. All four subspecies in Colorado readily
hybridize with other subspecies of cutthroat trout as well as rainbow
trout (Salmo gairdneri). Competitive exclusion and genetic swamping
are both likely results of introducing exotic salmonids into small
native trout populations. The only "pure" populations of native cut-
throat trout remaining in Colorado are those that have been physically
isolated from stocked trout by some permanent instream barrier such as
a waterfall.
General management plans for the four threatened subspecies of cut-
throat trout native to Colorado are similar. Coordination with the
state DOW and cooperation with federal agencies is implicit in all of
the following steps.
a) Inventory headwater streams in the general range of each
subspecies in an attempt to discover reminant populations
and/or suitable habitats for reintroduction.
b) Eliminate existing exotic fish species in those areas judged
suitable and isolated enough to maintain the genetic homo-
geneity of the native subspecies.
c) Introduce native subspecies back into their former range from
known populations of pure stock. It should be emphasized that
restocking occur only in the natural drainage of the fish.
Under no conditions should any endangered species of fish be
stocked into a major drainage not included in its original
range.
d) The newly established populations should be checked frequently
for reproductive success and the absence of exotic introduc-
tions.
e) Fishing in the areas should be discouraged until the popula-
tions are judged able to sustain a limited harvest. Because
of the general susceptibility of these species to angling,
it should be recognized these "brood populations" may never
be able to sustain a general harvest.
Three of the major drainages of the state (Colorado River, Rio Grande
and Arkansas River).each evolved at least one endemic subspecies of
cutthroat trout, while one subspecies is found in both the Arkansas
and South Platte rivers, most likely the result of stream capture.
General descriptions and information on each follows.
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