7994

• UCREFRP Catalog Number: 7994
• Author: Duff, D. A., Tech. Ed.
• Title: Conservation Assessment For Inland Cutthroat Trout, Distribution, Status and Habitat Management Implications.
• USFW Year: 1996.
• USFW - Doc Type: \
• Copyright Material: NO

In Montana, the Montana Rivers Information System (MRIS) was updated in 1994 for westslope
cutthroat. This database contains many of the components of the questionnaire, therefore the
database was queried for information on this subspecies. The questionnaire was completed by Errol
Claire, Oregon Department of Fish and Wildlife, for westslope cutthroat populations in the John Day
River drainage, Oregon. Information for Washington was obtained through surveys and contacts with
state and federal biologists.

In most cases the information contained within this assessment represents the best professional
judgement of state and federal biologists in each state. There is a tremendous amount of information
that is unknown about westslope cutthroat trout populations, but Mure surveys should help to
overcome some of these deficiencies. The information presented here is a general synopsis to assess
the current distribution and status of westslope cutthroat across its range. The reader is encouraged
to obtain additional information from each state.

RESULTS AND DISCUSSION

Idaho

In Idaho, the historic range is believed to have been the Kootenai River drainage above its barrier falls,
and the Pend Oreille, Spokane, Clearwater, and Salmon river drainages. Behnke (1992) speculates
that Clearwater and Salmon river populations originated from heaclwater transfers from the Clark Fork
River after redband trout displaced Yellowstone cutthroat which was likely the original ancestor in
these drainages.

Historic abundance was thought to be high throughout this subspecies range (Rieman and Apperson
1989). Gilbert and Everman (1894) during their early explorations of the Columbia River reported that
the Pend Oreille River was "abundant with trout and salmon trout" They were referring to cutthroat
and bull trout. Region 1 Idaho Fish and Game Files contain reports from the St. Maries Courier
reporting from 1901 to 1905 that anglers caught 50-100 "speckled trout" averaging 3 to 5 Ibs.

More recently, estimates by Rieman and Apperson (1989) indicate that strong populations (> 50%
of historic potential) persist in 11 % of the historic range, while viable (strong and depressed) popula-
tions remain in 36% of their historic range (Table 1). Depressed populations were defined as <50%
of their historic potential but were considered viable and common in samples. The potential to restore
westslope cutthroat to historic levels was subjectively rated poor in 46% of this range due to their
limited importance as a fishery while 20% of the populations could be restored with special regula-
tions. Potential was classified as the fishery manager's ability to use restoration techniques, i.e.
species removal, barrier construction, hatchery supplementation, special regulations, and habitat
recovery (Rieman and Apperson 1989).

Genetic inventories in Idaho are limited; only the upper Priest Lake population has been genetically
tested (Personal Communication, Dave Cross, Idaho Panhandle National Forest). Suspected pure
(the drainage had no history of stocking of other trout) populations exist in 13% of their range with
only 4% of the historic range considered strong and pure (Rieman and Apperson 1989).

Decline in westslope cutthroat trout abundance was attributed to habitat loss in 87% of the streams,
while overfishing contributed to 47% of the decline. Competition was thought to affect 12% of the
population decline and genetic introgression 15% (Rieman and Apperson 1989). Habitat degradation
has negatively affected populations. Forest management, including but not limited to timber harvest,

3