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

The Forest Service (FS) and state wildlife agency later contributed to this impact and furthered the
BCT decline by significant increases in fish stocking activities on national forest streams and lakes,
including waters off NFS lands. In 1930, some 34.6 million fish were planted on NFS waters alone.
The NB cutthroat became extirpated in the Utah Lake system in the early 1930's, a victim of wide-
spread harvest, exotic introductions, and habitat-flow loss through irrigation diversions (Cope 1955,
USDA FS 1984, Hickman 1978).

The historical NB riverine habitat was estimated by this assessment at 1,178 stream miles within the
four major sub-basins (Table 6c). About 38% of these stream miles were historic habitat on three
national forests (Wasatch-Cache, Uinta, and Manti-LaSaI NF's). Occupied habitat occurs only on one
NF totaling 7.5 stream miles for four known NB populations, of which two are remnants and two are
transplants from remnant stocks (Table 4,5). These existing populations occupy only 1.6% of historic
national forest habitat. Human activities have caused extirpation of NB populations over an estimated
99% of historic sub-basin waters, and 98% on national forests waters. One NB remnant population
recently discovered occurs off national forest lands in the Parley's-Lambs Creek watershed, Jordan
River sub-basin (Woolf 1995). Expansion of this population onto the Wasatch-Cache NF in this
watershed is probable in the future through State management actions. The status of two NB
transplanted populations was recorded as .secure, expanding. (SEX). These populations in the
Wasatch-Cache NF, occur in a reservoir and stream within the Red Butte Natural Research Area, a
protected NF watershed. However, the reservoir could be eliminated in the future due to structural
instability, therefore, severely reducing the BCT population and its use as a brood stock area. Habitat
condition is indicated as "good. and trend in abundance is .increasing. (Table 13). Status of the two
remnant populations, one each in the Weber River and Jordan River sub-basins is .at-risk, declining"
(ARD) in the Weber River and .secure, expanding. (SEX) in the Jordan River. National forest activities
and man's encroachment continue to place these populations .at-risk.. While habitat trend is .stable"
for both populations, overall condition varied from "fair" for the Weber River to .good" for the Jordan
River populations.

All four populations have had genetic evaluation completed (100%) for meristics and electrophoretic
validation as pure populations, and 75% have been validated with mONA (Table 7). Exotic fish,
primarily rainbow trout and other cutthroat trout are present in or immediately adjacent to 100% of
the occupied habitats, and are viewed as a threat to all populations. All populations are considered
resident in streams, and all are rare in abundance. Habitat condition factors have not impacted two
of the three Jordan River sub-basin populations. But one population, in and adjacent to the Twin
Peaks Wilderness, Is subject to angling pressure and declining population. The Weber River popula-
tion is affected by dewatering, lack of woody debris, changes in channel morphology, and streambed
sedimentation, primarily associated with livestock grazing activities (Table 15).

There is still considerable uncertainty regarding possible suspect NB populations. Two populations
(Ogden and Spanish Fork sub-basins) are suspect but need further genetic evaluation to ascertain
pure status. Initial genetic testing is cautious in assuming purity because of possible intermixing and
close association with Yellowstone cutthroat trout and BRB populations (Dennis Shiozawa, Brigham
Young University, personal communications 1996). But efforts are underway by the Wasatch-Cache
NF and Utah Division of Wildlife Resources to investigate certain additional waters as part of the BCT
conservation strategy for Utah (UDWR 1996).

Southern Bonneville

The assessment area includes that portion of the Bonneville Basin within the Sevier River and
Escalante Lake sub-basins in south-central Utah. Included within this historic habitat range are nine

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