[Federal Register: September 9, 2008 (Volume 73, Number 175)]
[Proposed Rules]
[Page 52235-52256]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09se08-21]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R6-ES-2008-0023; 1111 FY07 MO-B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List the Bonneville Cutthroat Trout as Threatened or
Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of a 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our
12-month finding on a petition to list the Bonneville cutthroat trout
(Oncorhynchus clarkii utah) as a threatened subspecies throughout its
range in the United States, pursuant to the Endangered Species Act of
1973, as amended (Act). After a thorough review of all available
scientific and commercial information, we find that listing the
Bonneville cutthroat trout as either threatened or endangered is not
warranted at this time. We ask the public to continue to submit to us
any new information that becomes available concerning the status of or
threats to the subspecies. This information will help us to monitor and
encourage the conservation of the subspecies.
DATES: The finding in this document was made on September 9, 2008.
ADDRESSES: This finding is available on the Internet at http://
www.regulations.gov. Supporting documentation we used in preparing this
finding is available for public inspection, by appointment, during
normal business hours at the U.S. Fish and Wildlife Service, Utah
Ecological Services Office, 2369 West Orton Circle, Suite 50, West
Valley City, Utah 84119; telephone (801) 975-3330. Please submit any
new information, materials, comments, or questions concerning this
finding to the above address or via electronic mail (e-mail) at paul_
abate@fws.gov.
FOR FURTHER INFORMATION CONTACT: Larry Crist, Field Supervisor, U.S.
Fish and Wildlife Service, Utah Ecological Services Office (see
ADDRESSES section). If you use a telecommunications device for the deaf
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act) (16 U.S.C. 1531 et seq.), requires that, for any petition
to revise the List of Endangered and Threatened Species that contains
substantial scientific and commercial information that listing may be
warranted, we make a finding within 12 months of the date of receipt of
the petition on whether the petitioned action is: (a) Not warranted,
(b) warranted, or (c) warranted but the immediate proposal of a
regulation implementing the petitioned action is precluded by other
pending proposals to determine whether species are threatened or
endangered, and expeditious progress is being made to add or remove
qualified species from the List of Endangered and Threatened Species.
Section 4(b)(3)(C) of the Act requires that a petition for which the
requested action is found to be warranted but precluded be treated as
though resubmitted on the date of such finding, that is, requiring a
subsequent finding to be made within 12 months. Such 12-month findings
must be published in the Federal Register.
Previous Federal Actions
On February 26, 1998, we received a petition, dated February 5,
1998, from the Biodiversity Legal Foundation requesting that the
Service list the Bonneville cutthroat trout (Oncorhynchus clarkii utah)
(BCT) as threatened in U.S. river and lake ecosystems where it
continues to exist, and to designate its occupied habitat as critical
habitat within a reasonable period of time following the listing. On
December 8, 1998, we published a 90-day petition finding for the BCT in
the Federal Register (63 FR 67640). We found that the petition
presented substantial information indicating that the subspecies may be
warranted for listing under the Act, and initiated a review of the
subspecies' status within its historic range.
In the 1998 90-day finding, we solicited additional data, comments,
and suggestions from the public, other governmental agencies, the
scientific community, industry, and other interested parties concerning
the status of the BCT throughout its range. The comment period for
submission of additional information ended on January 7, 1999, but was
reopened (64 FR 2167) during January 13 through February 12, 1999. We
published a 12-month finding in the Federal Register on October 9, 2001
(66 FR 51362), and documented that the BCT was not warranted for
listing under the Act because it was neither endangered nor likely to
become endangered within the foreseeable future throughout all or a
significant portion of its range.
On February 17, 2005, we were sued by the Center for Biological
Diversity, and others, on the merits of the 12-month finding. On March
7, 2007, the District Court of Colorado dismissed the lawsuit after
determining that Plaintiffs failed to demonstrate the not warranted
finding was arbitrary, capricious, or contrary to law. The Plaintiffs
appealed to the 10th Circuit Court of Appeals on May 4, 2007.
On March 16, 2007, in the interim between the lawsuit dismissal and
appeal, the Solicitor of the Department of the Interior issued a formal
opinion regarding the legal interpretation of the term ``significant
portion of the range'' of a species (DOI 2007). The opinion provides
guidance on analysis intended to determine whether a species is in
danger of extinction throughout a significant portion of its range when
it is not in danger of extinction throughout its entire current range.
Because this opinion was pertinent to the BCT decision, we withdrew the
2001 12-month finding for BCT (USFWS 2007, entire), and initiated a new
status review to include significant portion of the range analysis. We
published a notice in the Federal Register (73 FR 7236) announcing the
opening of a comment period from February 7 through April 7, 2008. The
notice specified that the new status review would include consideration
and analysis of all information previously submitted, and any new
information provided regarding the status of the BCT.
Species Biology
The BCT is native to the Bonneville basin, and is 1 of 14
subspecies of cutthroat trout recognized by Behnke (1992, pp. 3-21,
132-138) that are native to interior regions of western North America.
BCT generally have large, evenly distributed spots, but a high degree
of intra-basin variation exists. BCT tend to develop large, pronounced
spots that are evenly distributed on the sides of the body rather than
concentrated posteriorly as in the Yellowstone cutthroat trout
(Oncorhynchus clarkii bouveri)
[[Page 52236]]
subspecies. Coloration in BCT is generally dull compared to other
cutthroat subspecies; however, coloration can vary depending on
environmental conditions and local genetic composition (Behnke 1992,
pp. 132-138).
Vertebrae typically number 62-63, slightly higher than in other
subspecies. Scales in lateral series average 150-170. BCT average
between 16-21 gill rakers, with a mean of 18-19, except the Snake
Valley type, which have 18-24 (mean, 20-22). Another important
characteristic of all cutthroat subspecies is the presence of
basibranchial teeth, which are absent in rainbow trout (Behnke 1992, p.
132). Numbers of basibranchial teeth provide information about
subspecies derivation and relatedness. The Snake Valley type have
profuse basibranchial teeth, averaging 20-28, while most other BCT
average 5-10 (Behnke 1992, p. 132).
Life strategies exhibited by BCT include stream resident (occupy
home ranges entirely within relatively short reaches of streams),
fluvial (migrate as adults from larger streams or rivers to smaller
streams to reproduce), adfluvial (migrate, sometimes many kilometers,
as mature adults from lakes to inlet or outlet streams to spawn), and
lacustrine (lake) forms. The life strategy that a particular BCT
population exhibits likely depends on a combination of environmental
conditions and genetic plasticity of inherited traits. Very little
information is available to suggest the extent of plasticity and what
environmental characteristics may cue a successful shift in life
strategy. Most information is based on the success or failure of
transplants of various life forms among different aquatic ecosystems.
Furthermore, evidence suggests that BCT populations within a single
stream can comprise multiple life history strategies (resident,
fluvial, adfluvial), and that individuals may use mainstem rivers to
move between and among drainages where they are not fragmented by water
diversions or barriers (Kershner et al. 1997, entire).
May et al. (1978, p. 19) found that male BCT sexually matured at
age 2 while females matured at 3 years of age. However, Bear Lake BCT
were reported to mature much later, with adults normally beginning to
mature at 5 years of age but not spawning until age 10 (Neilson and
Lentsch 1988, p. 131). Both the age at maturity and the annual timing
of spawning vary geographically with elevation, temperature, and life
history strategy (Behnke 1992, p. 136; Kershner 1995, pp. 28-30). Lake
resident trout may begin spawning at 2 years and usually continue
throughout their lives, while adfluvial individuals may not spawn for
several years (Kershner 1995, pp. 28-30). Annual spawning of BCT
usually occurs during the spring and early summer at higher elevations
at temperatures ranging from 4-10 [deg]C (May et al. 1978, p. 19). May
et al. (1978, p. 19) reported BCT spawning in Birch Creek, Utah,
beginning in May and continuing into June. BCT in Bear Lake began
spawning in late April and completed spawning in June (Nielson and
Lentsch 1988, p. 131). The wild broodstock at Manning Meadow Reservoir
(9,500 feet elevation) spawn from late June to early July (Hepworth and
Ottenbacher 1997, p. 1). In Lake Alice, Wyoming, fish were predicted to
spawn from late May until mid-June (Binns 1981, p. 47).
Fecundity of cutthroat is typically 1,200-3,200 eggs per kilogram
(kg) (2.2 pounds (lbs)) of body weight (Behnke 1992, p. 33). In Birch
Creek, a 147 millimeters (mm) (5.8 inches (in)) BCT female produced 99
eggs, a 158 mm (5.8 in) female produced 60 eggs and a 176 mm (6.9 in)
female produced 176 eggs (May et al. 1978, p. 19). Whereas in Raymond
Creek, Wyoming, 3 females ranging from 124 to 246 mm (4.9 to 9.7 in)
averaged 165 eggs (Binns 1981, p. 48). Evidence suggests fecundity of
lake-dwelling BCT is greater. Fecundity of females in Lake Alice
averaged 474 eggs/female (Binns 1981, p. 48), while females in Manning
Meadow, Utah, averaged 994 eggs/female (D. Hepworth, Utah Division of
Wildlife Resources, unpubl. data). Incubation times for wild BCT have
not been verified, but Platts (1957, p. 10) suggested eggs hatch and
fry begin to emerge approximately 45 days after spawning, depending on
temperature.
Larvae typically emerge in mid-to-late summer, depending on
spawning times. Once emerged, larvae or fry, as they are commonly
called, are poor swimmers and typically migrate to stream margins.
Adfluvial BCT spend 1 or 2 years in streams before migrating to the
Lake (Nielson and Lentsch 1988, p. 131).
Growth of resident BCT is highly dependent on stream productivity.
In general, growth of trout tends to be slower in high-elevation
headwater drainages than in lacustrine environments, but this likely
depends on temperatures and food base. In Birch Creek, Utah, age 1 fish
averaged 84 mm (3.3 in), age 2 fish averaged 119 mm (4.7 in), age 3
fish averaged 158 mm (6.2 in), and age 4 fish averaged 197 mm (7.8 in)
in length (May et al. 1978, p. 17). Growth in two Wyoming streams was
faster, and age 4 fish averaged 282 to 320 mm (11.1 to 12.6 in) in
length (Binns 1981, p. 44). In contrast, BCT in Bear Lake grow to an
average size of 560 mm (22.0 in) and 2 kg (4.4 lbs) (Nielson and
Lentsch 1988, p. 131). Historic accounts of BCT in Utah Lake suggest
fish may have reached a meter in length (Notes from Yarrow and Henshaw
in 1872 as described by Tanner 1936). Platts (1957, p. 10) reported
that some BCT taken from Utah Lake a century ago attained weights of
over 11.3 kg (25 lbs).
Little is known about feeding habits of BCT. In general, BCT trout
are insectivorous, especially in stream habitats. Both terrestrial and
aquatic insects appear to be important to their diet (May et al. 1978,
pp. 7-10; Binns 1981, p. 48). In Birch Creek, May et al. (1978, pp. 9-
10) reported BCT diets were diverse in summer, while in the fall in
Trout Creek, Utah, their diet consisted primarily of terrestrial
insects. Dipterans and debris were the dominant food items for immature
trout, while terrestrial insects were the dominant prey for mature
individuals. BCT may display more plasticity in feeding habits
depending on the system or specific population characteristics. Little
information has been collected on BCT to understand the extent of
feeding shifts of BCT. Platts (1957, p. 4) suggested that cutthroat do
not need to feed on fish to attain large sizes but will do so where
insects are not abundant.
Interactions With Nonnative Fish
BCT may or may not persist when nonnative trout are stocked into
BCT waters. The actual mechanism that dictates the survivorship of BCT
in the presence of nonnatives is unknown, but the recent discovery that
numerous BCT populations have persisted for decades in the presence of
rainbow trout (Oncorhynchus mykiss), Yellowstone cutthroat trout, and
other nonnatives suggests BCT is not always displaced by nonnatives as
previously thought. However, BCT can hybridize with rainbow trout and
Yellowstone cutthroats in some situations and be displaced by the
superior competitor, brook trout (Salvelinus fontinalis). The degree of
hybridization appears to vary with the persistence of the stocked fish
and also with habitat conditions as does the level of competition with
brook trout.
Benhke (1992, p. 107) reported that BCT native to the Bear River
drainage adapted to the harsh and fluctuating environments of desert
basin streams, remaining the dominant trout today in many streams where
nonnative trout were introduced. This seems to be a fairly unique trait
of BCT compared to other cutthroat subspecies. There is still no
specific rationale as to why BCT would persist better than other desert
[[Page 52237]]
cutthroat subspecies, yet something in its unique genetic composition
seems to allow BCT to persist where other cutthroat subspecies have
been found to be displaced.
For example, Bear Lake BCT, probably due to the unique
environmental conditions in which they developed, have resisted
hybridization with and replacement by nonnative trout. Yellowstone
cutthroat trout, Yellowstone cutthroat rainbow trout hybrids, and
rainbow trout were consistently stocked into Bear Lake for decades.
Benhke (1992, p.137) examined specimens from Bear Lake and compared
these to museum specimens from the lake and with cutthroat trout from
the Bear River drainage and found no evidence of hybridization among
their taxonomic characters. Nielson and Lentsch (1988, p.130) similarly
reported that, after examining the DNA of 52 Bear Lake specimens, no
rainbow trout alleles were observed in any fish.
Since the early 1990's, many additional remnant BCT populations
have been found in streams that had been stocked with rainbow trout or
Yellowstone cutthroat trout (Utah Division of Wildlife Resources,
unpublished data). These BCT populations were assumed to be lost
through hybridization until recent surveys found BCT present. Results
of these surveys suggest BCT have retained much of their natural
genetic integrity despite intensive nonnative stocking efforts.
Introduced brook trout have been stocked, legally and illegally,
into some BCT waters. BCT do not hybridize with brook trout, but brook
trout are thought to acquire resources better and reproduce and recruit
more efficiently than BCT. The specific mechanism of how brook trout
displace BCT is unknown, but greater fecundity, earlier maturity, and
tolerance of higher densities gives brook trout an advantage over the
native BCT (Griffith 1988, p. 105; Fausch 1989, pp. 307-312). The
extent of threat to BCT from brook trout varies depending on
environmental conditions of the stream. Although not considered the
greatest threat to the persistence of BCT, competition from introduced
brook trout can and has displaced native BCT populations.
Habitat Requirements
Trout, regardless of their evolutionary history, require 4 types of
habitat during various stages of their life history: spawning habitat,
nursery or rearing habitat, adult habitat, and overwintering habitat.
Spawning gravels are required for spawning success and can be a
limiting factor in high-gradient streams where the current carries off
suitable spawning gravel (Behnke 1992, p. 25). Conversely, an even
greater concern may be accumulation of fine sediments into interstitial
spaces of spawning gravels, which prevents egg incubation and reduces
larval survival. Such fines can become dominant in the sediments when
poor land-use practices alter flow regimes, remove riparian vegetation,
and/or degrade overall watershed conditions. These human-induced
activities can aggravate already fragile soils and geology in
vulnerable desert climates.
Little information is available on specific habitat requirements
for BCT; however, there is a wealth of information on salmonid habitat
conditions in general which appear to generally represent those of BCT
(Pennak and Van Gerpen 1947, entire; Binns and Eiserman 1979, entire;
Scarnecchia and Bergersen 1987, entire). For example, well-oxygenated
water, cooler temperatures in general and a complexity of instream
habitat structure, such as large woody debris and overhanging banks,
are considered good trout habitat conditions. For various species,
subspecies, and local forms, adaptations and tolerance of these
conditions varies. BCT have also been found to survive and be fairly
robust in what is considered marginal salmonid habitat conditions
(e.g., turbid water, fine sediments, warmer temperatures, poor
structural habitat). This may be because BCT have evolved in a desert
environment where climate can cause fluctuations in water and sediment
regimes and environmental condition (Behnke 1992, p. 107).
It was previously thought that with the exception of three
lacustrine systems, Bear Lake (Utah and Idaho), Utah Lake, and Alice
Lake (Wyoming), BCT were historically found in cool headwater streams
throughout the Bonneville basin. However, more recent research and
status and genetic surveys reveal BCT populations are found at high,
moderate, and low elevations (within the range of elevations in the
Bonneville Basin) in small headwater streams, such as those of the
north slope of the western Uintas, to larger mainstem rivers, such as
the Thomas Fork of the Bear River (UDWR, unpublished data).
Historic Habitat
BCT likely historically occupied all suitable habitats within the
Pleistocene Lake Bonneville basin, which included portions of Idaho,
Nevada, Utah, and Wyoming. The desiccation of ancient Lake Bonneville
about 8,000 years ago likely fragmented the BCT into remaining streams
and lakes throughout the basin, resulting in several slightly
differentiated groups of BCT, including: (1) The Bear River basin; (2)
the Bonneville basin proper, including the Wasatch Mountain and Sevier
River drainages; and (3) the Snake Valley, an arm of ancient Lake
Bonneville that was isolated during an earlier desiccation event
(Behnke 1992, pp. 132-138). There is general consensus among the
scientific community, including the Service, that all these groups
represent the BCT subspecies (Shiozawa 2008, p. 1). For the purposes of
this finding, all three groups are considered BCT.
The BCT Conservation Team, which includes biologists from Wyoming
Game and Fish Department (WGFD), Utah Division of Wildlife Resources
(UDWR), Nevada Division of Wildlife (NDOW), Idaho Department of Fish
and Game (IDFG), Bureau of Land Management (BLM), U.S. Forest Service
(USFS), the National Park Service (NPS), and the Service, completed a
status report (May and Albeke 2005) that describes the rangewide status
of BCT in the United States. The rangewide status report summarized the
best available information on BCT (May and Albeke 2005, pp. i, 16, 103-
104). The status report was peer reviewed by five recognized experts in
the fields of fishery biology, conservation biology, and genetics. The
peer reviewers found that the status report provided sound scientific
data to use in this 12-month finding.
The 2001 finding on Bonneville Cutthroat Trout included 28,863
hectares (71,322 acres) of lake habitat (indicated as an adfluvial life
history) (USFWS 2001, pp. 34, 44, 50, 75). The 2005 BCT rangewide
status report relied on a protocol that was not designed to address
lake populations; however, 8 lakes connected to occupied stream habitat
were included as 412 stream kilometers (km) (256 stream miles (mi))
(May and Albeke 2005, pp. 107, 110, 120). Thus, throughout the
remainder of the document, all occupied BCT habitat is reported as
stream habitat and includes lake populations. These lake populations
are an important component in conserving BCT, and some lakes are
specifically designated to preserve genetically pure populations
(Donaldson 2008, pp. 8-9).
The BCT Conservation Team's status report included an analysis of
probable historic distribution (May and Albeke 2005, pp. 6, 16-19). Our
understanding of BCT historic distribution is based on habitat thought
to be occupied around 1800. The determination of occupation in this era
was based on historic
[[Page 52238]]
climactic conditions, stream channel gradient, barriers that would
preclude fish, and expertise of fishery biologists familiar with each
watershed. The analysis resulted in 10,876 (km) (6,758 mi) of stream
habitat potentially occupied historically (May and Albeke 2005, pp. 6,
16-19). This analysis included estimated stream miles for historically
occupied BCT lakes because the analysis protocol was not designed to
address lake populations separately. The historically occupied habitat
identified in each State included: Utah--7,916 km (4,919 mi) (73
percent); Idaho--1,854 km (1,152 mi) (17 percent); Wyoming--974 km (605
mi) (9 percent); and Nevada--132 km (82 mi) (1 percent) (May and Albeke
2005, pp. 6, 16-19). The United States is divided and sub-divided into
successively smaller hydrologic units that are classified into four
levels: regions, sub-regions, accounting units, and cataloging units.
Fourth-level hydrologic unit codes (HUCs) in the Lake Bonneville Basin,
including Pine Valley, Tule Valley, Pilot-Thousand Springs, Northern
Great Salt Lake Desert, Lower Beaver, and Sevier Lake, were not
included as historical habitats because they were judged unsuitable due
to extreme conditions, because information on them prior to 1800 is
unavailable, or because historical records indicate that they were
devoid of fish.
Current Distribution
Current distribution of BCT is approximately 3,830 km (2,380 mi)--
35 percent of the probable historically occupied stream miles (May and
Albeke 2005, p. 19). Currently occupied habitat identified in each
State includes Utah--2,438 km (1,515 mi) (64 percent); Idaho--869 km
(540 mi) (23 percent); Wyoming--476 km (296 mi) (12 percent); and
Nevada--47 km (29 mi) (1 percent) (May and Albeke 2005, p. 19).
The BCT is well distributed throughout its range in four watershed-
based GMUs (see Figure 1; Table 1 below). In earlier assessments, five
GMUs or GUs (geographic units) were identified as including current
populations of BCT; however, we combined the Bear Lake and Bear River
GMUs because they occur within one watershed, and our analysis was
conducted by watershed (May and Albeke 2005, pp. 4-5). This
reconfiguration of GMUs does not imply a reduction in the geographic
area where BCT occur (May and Albeke 2005, pp. 2-5).
Within each GMU, streams were identified to the 4th-level
hydrologic unit and assigned to a HUC. BCT occupy habitat in 22 of the
23 HUCs determined to likely have supported historical habitat. BCT
also occupy habitat in three HUCs that are either partially or totally
outside of the subspecies historic range (May and Albeke 2005, pp. 19-
20); most of these populations were reintroduced into suitable habitat
with no record of nonnative fish (Behnke 1992, pp. 134-135). The Bear
River GMU has the greatest extent of currently occupied BCT habitat
(2,010 km/1,249 mi), followed by the Northern Bonneville (1,532 km/952
mi), Southern Bonneville (187 km/116 mi), and the West Desert (101 km/
63 mi).
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Table 1--From May and Albeke 2005, (p. 19), Table 21 (p. 34)
----------------------------------------------------------------------------------------------------------------
Km (mi) occupied
Km (mi) currently Number of BCT by BCT
GMU name occupied by BCT conservation conservation
populations populations
----------------------------------------------------------------------------------------------------------------
Bear River............................................. 2,010 (1,249) 33 1,753 (1,089)
Northern Bonneville.................................... 1,532 (952) 65 1,318 (819)
Southern Bonneville.................................... 187 (116) 21 145 (90)
West Desert............................................ 101 (63) 34 101 (63)
--------------------------------------------------------
Totals............................................. 3,830 (2,380) 153 3,316 (2,061)
----------------------------------------------------------------------------------------------------------------
Hybridization
Hybridization is a concern for many cutthroat trout populations. An
introgressed population results when a nonnative species or subspecies
is introduced into or invades native cutthroat trout habitat, the two
species then interbreed (i.e., hybridize), and the resulting hybrids
survive and reproduce. If the hybrids backcross with one or both of the
parental species, genetic introgression occurs. Continual introgression
can eventually lead to the loss of genetic identity of one or both
parent species, thus resulting in a ``hybrid swarm'' consisting
entirely of individual fish that often contain variable proportions of
genetic material from both of the parental species.
Our criteria for considering the potential impact of introgressed
populations of BCT are consistent with a position paper, titled
``Genetic Considerations Associated with Cutthroat Trout Management,''
developed by the fish and wildlife agencies of the intermountain
western States (UDWR 2000a, pp. 1-9). Signatories to the position paper
include the IDFG, Montana Fish Wildlife and Parks, NDOW, New Mexico
Game and Fish Department, UDWR, and WGFD. The document identified, for
all subspecies of inland cutthroat trout, three tiers of natural
populations for prioritizing conservation and management options under
State fish and wildlife management authorities: (1) Core conservation
populations composed of greater than 99 percent cutthroat trout genes;
(2) conservation populations that generally ``have less than 10 percent
introgression, but in which introgression may extend to a greater
amount depending upon circumstances and the values and attributes to be
preserved''; and (3) cutthroat trout sport fish populations that, ``at
a minimum, meet a species'' phenotypic expression defined by
morphological and meristic characteristics (counts of body parts) of
cutthroat trout.''
The premise of the position paper on genetic considerations was
that populations must conform, at a minimum, to the morphological and
meristic characteristics of a particular cutthroat trout subspecies in
order to be included in a State's conservation and management plan for
that subspecies. Conservation populations of a cutthroat trout
subspecies include fish believed to have uncommon or important genetic,
behavioral, or ecological characteristics relative to other populations
of the subspecies. Sport fish populations, conversely, while conforming
morphologically (and meristically) to the scientific taxonomic
description of the subspecies, do not meet the additional genetic
criteria of conservation or core, and are managed for their value as
sport fish rather than for conservation of the subspecies.
Following the State management agencies' position paper (UDWR
2000a, pp. 1-9), a ``core population'' is genetically unaltered (pure),
and a ``conservation population'' is pure (a core population) or
slightly introgressed (typically less than 10 percent) due to past
hybridization, yet has attributes worthy of conservation. Therefore,
conservation populations include both core populations (genetically
pure) and populations that are less than 10 percent introgressed with
rainbow trout or other subspecies of cutthroat trout (May and Albeke
2005, p. 71). The BCT rangewide status report (May and Albeke 2005, p.
31) identified 153 stream populations (3,316 km/2,061 mi) as
conservation populations (see Table 1, above, and Figure 2). Of the 153
conservation populations, 73 (732 km/455 mi) are considered core
populations containing genetically pure BCT.
We consider all core and conservation populations, as defined under
the States' standards and as described by May and Albeke (2005, p. 31),
for purposes of conducting this status review. Because the categories
are nested (conservation populations include core populations), we
refer to them collectively as ``BCT conservation populations'' in the
remainder of this finding. Some of the data presented in May and Albeke
(2005) pertains to all BCT populations (including sport fish) or
habitat. Those areas of this document that do not specify
``conservation populations,'' therefore, are referring to all BCT
populations. We conducted our analysis on conservation populations
because we found that BCT with less than 10 percent introgression still
express important behavioral, life history, or ecological adaptations
of indigenous populations within the range of the subspecies, and
remain valuable to the overall conservation and survival of the
subspecies (Campton and Kaeding 2005, pp. 1323-1325). (See also Factor
E, Hybridization with Nonnative Fishes.)
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Conservation Populations
Designated BCT conservation populations exist throughout the
subspecies' historic range (May and Albeke 2005, p. 31)--in all four
States and in the four designated GMUs. BCT currently occupy some
habitat in 22 of the 23 HUCs historically occupied, and BCT that meet
the conservation population definition (less than 10 percent
introgressed) exist in 19 of those HUCs. BCT conservation populations
were also identified in two HUCs (Spring-Steptoe and Hot Creek-Railroad
Valley) outside historic range, and three additional conservation
populations were identified outside historical range within the Upper
Virgin HUC. The majority of conservation populations (65) occur in the
Northern Bonneville GMU occupying 1,318 km (819 mi). The remainder of
BCT conservation populations are relatively equally distributed among
the West Desert (34), Bear River (33), and Southern Bonneville (21)
GMUs. These populations occupy 101 km (63 mi), 1,753 km (1089 mi), and
145 km (90 mi) respectively (May and Albeke 2005, p. 34).
The majority of BCT conservation populations (101; 66 percent)
occur as isolated, non-networked populations (May and Albeke 2005, p.
34); 25 populations (16 percent) are weakly connected; 15 populations
(10 percent) are moderately connected; and 12 populations (8 percent)
have migratory forms and open migration corridors that make them
strongly connected. The strongly connected populations occur in Utah,
Idaho, and Wyoming in the Bear River Geographic Management Unit (GMU)
and Northern Bonneville GMU (May and Albeke 2005, pp. 34, 107, 115,
117).
BCT Population Trend
BCT population trend and status can be interpreted from results of
previous assessments conducted from the early 1970's through the
present time. Hickman (1978, pp. 121-122) identified approximately 15
populations he considered ``pure'' occupying approximately 34 km (21
mi) of stream habitat. Duff (1988, pp. 121-127) reported 41
``genetically pure'' BCT populations (39 stream populations) in
association with 304 km (189 mi) of stream habitat. A draft Service
status review that was never finalized reported 48 genetically pure BCT
populations throughout the Bonneville Basin (USFWS 1993, pp. 1-62).
Duff (1996, pp. 38-39) further refined his BCT population distribution
reporting 81 genetically ``pure'' populations occupying 377 km (234 mi)
of stream habitat. A Service status review found that BCT occupied a
total of 1,372 km (852 mi) of stream habitat and 28,352 ha (70,059
acres) of lake habitat totaling 291 populations (USFWS 2001, pp. iv-v).
BCT assessments conducted between 1978 and 1996 generally counted
populations that were thought to be genetically ``pure.'' The 2001
Service assessment determined the genetic status of each population but
was more inclusive and counted management, conservation, and potential
conservation populations (USFWS 2001, pp. viii-xi). The May and Albeke
(2005) assessment assessed the genetic status of each BCT population
and then categorized genetic status based on the criteria in the
State's genetic position paper (UDWR 2000a, pp. 1-9).
Methods for tallying the number of individual BCT populations
tended to vary by individual assessment, with earlier assessments
tending to split tributary populations from mainstem river reaches. In
contrast, methods used for the May and Albeke (2005, p. 64) assessment
tended to group populations by higher order streams, thereby reducing
the total count of populations. Thus, it is important to consider
changes in the amount of occupied habitat when assessing population
trends from different assessments rather than to simply rely on changes
in number of populations. The number of known stream miles occupied by
BCT conservation populations increased over time from 15 populations in
34 km (21 mi) of habitat in 1978 to 153 populations in 3,316 km (2,061
mi) in 2004. Some of the increase in BCT conservation populations and
their habitat is the result of conservation actions such as the
discovery of more populations in recent years; the expansion or
restoration of populations; and the eligibility of populations for
conservation status (through genetic testing) that were previously
considered hybridized. Increases in the amount of BCT conservation
population habitat is also due to the use of a more accurate GIS-based
assessment method that incorporated the National Hydrography Dataset
geodatabase (May and Albeke 2005, p. 2) and also the inclusion of lakes
as river miles as used in the most recent assessment protocol (see
above), although the increase due to the inclusion of lakes in the
river mile calculation only accounts for an additional 412 km (256 mi)
of stream habitat.
The BCT Conservation Team's most recent analysis of the number of
BCT conservation populations and the extent of their habitat indicates
that conservation populations have increased from 153 populations in
3,316 km (2,061 mi) in 2004 (May and Albeke 2005, p. 31), to 172
populations in 3,333 km (2,071 mi) in 2008 (Burnett 2008a, entire).
This most recent evaluation of the BCT Conservation Team's database was
cursory and was not performed for other population parameters discussed
in May and Albeke (2005) (i.e., restoration activities, genetic status,
population health and densities, etc.); however, it does indicate that
the number of BCT conservation populations and their habitat continue
to increase.
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533), and implementing regulations
at 50 CFR 424, set forth procedures for adding species to the Federal
Lists of Endangered and Threatened Wildlife and Plants. In making this
finding, we summarize information regarding the threats to the BCT in
relation to the five factors provided in section 4(a)(1) of the Act.
In making this finding, we considered all scientific and commercial
information that we received or acquired up to the publication of the
2001 12-month finding (66 FR 51362), and after publication of the
notice initiating this finding (73 FR 7236; February 7, 2008). We
relied primarily on published and peer-reviewed documentation for our
conclusions, and most significantly, the rangewide status report
competed by the BCT Conservation Team (May and Albeke 2005, entire).
Pursuant to section (4) of the Act, a species may be determined to
be an endangered or threatened species on the basis of any of the
following five factors: (A) Present or threatened destruction,
modification, or curtailment of habitat or range; (B) overutilization
for commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) inadequacy of existing regulatory mechanisms;
or (E) other natural or manmade factors affecting its continued
existence. We evaluated whether threats to the BCT may affect its
survival. Our evaluation of threats, based on the best scientific and
commercial information available, is presented below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of the Species' Habitat or Range
Land use activities associated with each BCT conservation
population were
[[Page 52243]]
identified and documented in May and Albeke (2005, p. 52, Table 30),
but the significance of the activities was not determined in relation
to individual populations or to the conservation of the subspecies.
Non-angling recreation (camping, hiking, ATV use, etc.) occurs in 69
percent of the conservation populations. Livestock grazing occurs in 58
percent of the conservation populations, roads in 69 percent, timber
harvest in 20 percent, and dewatering in 30 percent. Hydroelectric
plants, water storage, or flood control occurs in 20 percent of the
conservation populations. A small percentage of populations have mining
or nonnative fish stocking. Many populations have more than one land
use occurring in the area.
A comprehensive assessment of the effects of land management
practices on BCT does not exist. However, an evaluation of habitat
quality was conducted for currently occupied habitat (May and Albeke
2005, p. 26). The evaluation considered both natural habitat features
and human-caused disturbances. A stream ranked as ``excellent'' if it
had ample pool habitat, low sediment levels, optimal temperatures, and
quality riparian habitat. A ``good'' habitat quality rating indicated
the presence of some less than ideal attributes, and ``fair'' indicated
the presence of a greater number of less than ideal attributes. A
``poor'' habitat quality rating indicated the inferior conditions of
most habitat attributes. Of total occupied habitat for all BCT
populations, excellent habitat conditions occurred in approximately 196
km (122 mi) (5 percent); good conditions occurred in 1,801 km (1,119
mi) (47 percent); fair conditions occurred in 1,080 km (671 mi) (28
percent); poor conditions occurred in 628 km (390 mi) (16 percent), and
unknown conditions occurred in 126 km (78 mi) (3.2 percent). The
majority of occupied habitat (80 percent) is in fair, good, or
excellent condition.
Livestock grazing occurs in 58 percent of the BCT populations.
Livestock grazing became an acute problem for watershed health in the
late 1880s through 1930s when grazing, particularly sheep grazing, was
so extensive and ill-managed that widespread watershed damage occurred
throughout many areas in the Bonneville Basin. In fact, at the turn of
the century, sheep were crowding cattle out of many areas (Peterson and
Speth 1980, p. 179). In the Wasatch Mountains east of Salt Lake City,
Utah, over-grazing of sheep denuded mountain meadows, some to the
extent that watersheds experienced massive soil loss, land-slides and
severe erosional damage. In addition to resident sheep, Utah was at a
geographical `crossroads of the west' where hundreds of sheep were
trailed to and from neighboring States (Peterson and Speth 1980, p.
179).
Overgrazing by sheep can be particularly damaging to overall
watershed conditions. Sheep have been known to graze vegetation down to
dirt and ``grub'' away at grass roots thereby damaging the soil mantle,
which acts to hold water for plant uptake (Peterson and Speth 1980,
p.180). The extensive watershed damage typical of over-grazing sheep in
the early 20th century led to massive soil erosion, land slides, and
flooding during heavy precipitation (Cottam 1947, pp. 23-29). Such
events can completely eliminate local fish populations and undoubtedly
affected local populations of BCT. For streams already fragmented from
diversions or dewatering, such events could have led to local
extirpation of BCT where no connected populations were available to
recolonize streams after a catastrophic flood.
Although cattle grazing can affect watershed conditions as well,
the greater concern for cattle grazing stems from direct stream impacts
where cattle are permitted to dwell in or are trailed through stream
channels and riparian areas. Without adequate management, cattle can
trample and destroy instream habitat and stream banks. They forage on
lush riparian vegetation, which leads to degraded stream conditions and
changes in channel morphology. Trampling destroys undercut banks
resulting in wider and shallower channel morphology. Where this occurs,
BCT can be impacted by increased water temperatures, loss of habitat
complexity, altered macroinvertebrate food-base, and increased
deposition of fine sediment (Platts 1991, p.393; Belsky et al. 1999,
p.420; Rinne 1999, p.14).
When livestock grazing is managed appropriately, it can occur in
the vicinity of stream and riparian habitat, and habitat conditions
that support fish populations can still be maintained (Fitch and Adams
1998, p. 197). The Western Watersheds Project, Inc. (Carter 2008, pp.
1-7) submitted information documenting grazing impacts in localized
areas in the Bear River GMU. Much of the information documents range
conditions relative to grazing allotment reauthorizations. The
information and conclusions presented included the assumption that, if
a land management activity occurred within the vicinity of a BCT
population, it was adversely affecting the population. We recognize
that overgrazing can cause adverse impacts to individual populations of
BCT. However, only 16 percent of the occupied stream miles have poor
habitat quality (May and Albeke 2005, p. 26). Specific information on
grazing impacts to BCT habitat on a rangewide basis is not available.
We found no information indicating that overgrazing significantly
affects the rangewide status of BCT now, or will do so in the
foreseeable future. Therefore, we conclude that overgrazing is not a
significant threat to BCT.
Roads, timber harvest, and dewatering occur in the area of some BCT
populations. Similar to water development and grazing, the greatest
impacts from timber harvesting occurred from 1850 to 1950. Although
timber harvesting still occurs on National Forest Lands and very
limited private lands in the Bonneville Basin, and may have some
detrimental impacts on streams and watersheds, timber harvesting
standards have substantially improved, particularly regarding
protection of streams and watershed condition, and the catastrophic
destruction that occurred in the first 100 years of pioneer settlement
no longer occurs.
Currently, timber harvesting affects BCT through the indirect
effects of road building and deforestation. Road building is known to
add fine sediment to streams where roads cross or follow stream
channels. These fine sediments can fill interstitial spaces important
for successful spawning and survival of eggs and larval fish as well as
alter the macro-invertebrate food base (Williams and Mundie 1978,
p.1032-1033). Deforestation can also add sediment input into streams
where riparian buffers are not implemented. Loss of trees also
increases water volume draining into stream channels, which can alter
flow and sediment regimes or exacerbate catastrophic flooding during
extreme precipitation events.
Within the Bonneville Basin, timber harvesting is fairly limited
compared to other areas of the inland west, mainly because the arid
climate is not conducive to extensive, lush forests. Timber harvest
occurs in only 20 percent of BCT conservation population habitat (May
and Albeke 2005, p. 52, Table 30). We found no information indicating
that timber harvesting significantly affects the rangewide status of
BCT now, or will do so in the foreseeable future. Therefore, we
conclude that timber harvesting is not a significant threat to BCT.
Direct effects of water diversions and depletions (dewatering) on
BCT occur where reaches are dewatered or made inaccessible by instream
barriers. Secondary effects of water development may include higher
water temperatures
[[Page 52244]]
in summer months because of lower water volume and diminished riparian
condition and altered instream and shoreline habitat, all of which can
impact cutthroat trout spawning and populations (Clancy 1988, pp. 40-
41). Dewatering occurs in only 30 percent of BCT conservation
population habitat (May and Albeke 2005, p. 52, Table 30). Rates of
habitat loss through water diversions and depletions were likely
heaviest for the decades immediately after pioneer settlement, in the
late 1800s, throughout the Bonneville Basin near locations of
population growth. We found no information indicating that dewatering
significantly affects the rangewide status of BCT now, or will do so in
the foreseeable future. Therefore, we conclude that dewatering is not a
significant threat to BCT.
Idaho and Nevada have no producing oil or gas wells in BCT areas.
However, oil and gas development has been accelerating over the last
several years in Utah and Wyoming. Oil and gas development could affect
BCT through increased land disturbance from roads and pads that could
cause water quality problems associated with increased sediment loads,
and through leaks, spills, and discharge of produced water reaching BCT
habitat (WGFD 2004, pp. 25-26). The BLM and Utah Division of Oil Gas
and Mining provided information on locations of existing active and
inactive wells and oil and gas leases on BLM, USFS, and other lands
where BLM has jurisdiction over the subsurface mineral rights within
the BCT range in Utah and Wyoming (BLM 2008a, entire; UDOGM 2008,
entire). A well exists within 1.6 km (1 mi) or less of 26 BCT
conservation populations (17 percent of all conservation populations).
Of these 26 populations, 2 were near active or producing wells; the
wells near the remaining 24 populations were non-producing and were
shut-in, plugged and abandoned, or abandoned entirely for development.
These non-producing wells have a greatly reduced likelihood of
releasing oil and gas related contaminants into BCT habitat (BLM 2008b,
entire). Relatively little overlap exists between oil and gas
development sites and BCT conservation populations. BCT populations
typically occur at higher elevations where minimal oil and gas activity
exists. An analysis of potential future oil and gas development for the
States of Wyoming and Utah indicates that the majority of leases occur
outside the historic range of BCT (BLM 2008b, entire). Potential
impacts to BCT resulting from oil and gas development on Federal land
are typically assessed through the National Environmental Policy Act
(NEPA) review process; as a result, future effects should be disclosed
and effects to BCT will have to be taken into consideration due to the
sensitive species management status of BCT on Federal land. Therefore,
based on the best scientific and commercial information available, we
conclude that dewatering is not a significant threat to BCT now, or in
the foreseeable future.
Summary of Factor A
Land use practices, such as livestock grazing, road construction
and maintenance, dewatering, and timber harvest, are occurring to some
extent in most areas of occupied habitat. However, habitat quality
ratings are fair, good, or excellent in 80 percent of BCT habitat
throughout the current range of the subspecies. Approximately half of
all BCT populations (49 percent) occur on Federal lands where land use
regulations are in place to ensure ongoing maintenance of existing
habitat (see Factor D). Restoration and conservation activities are
occurring for at least 57 percent of the conservation populations.
We find that the presence alone of an activity within a stream
segment containing a conservation population is not sufficient evidence
to conclude that the population is threatened or that a certain land
use activity affects all populations rangewide at a significant level.
Additional parameters, such as magnitude of impacts, distribution and
abundance of BCT populations, and population trends, lend to an overall
status determination. Many species exist in managed landscapes; not all
are significantly impacted by human-caused influences to the level of
being considered threatened under the Act.
BCT conservation populations are well distributed in four GMUs,
collectively forming a solid basis for persistence of BCT. These GMUs
contain 19 of the 23 HUCs determined to have supported historical BCT
habitat. In addition, BCT conservation populations currently occupy
habitat in three HUCs that are either partially or totally outside the
subspecies' historic range.
Based on the best scientific and commercial information available,
we conclude that BCT is not now or in the foreseeable future,
threatened by destruction, modification, or curtailment of its habitat
or range to the extent that listing under the Act as a threatened or
endangered species is warranted at this time.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
No commercial harvest of BCT currently occurs, so only recreational
angling could potentially result in overutilization. Data show that
angling occurs in 60 percent of BCT conservation populations (May and
Albeke 2005, p. 52). Utah, Idaho, and Wyoming have special regulations
providing protection against over-harvest of BCT. These special
regulations include catch-and-release requirements, limited harvest,
fishing closures, and tackle restrictions. In addition, the remote
location of many BCT streams provides protection from heavy fishing
pressure (NDOW 2006, p. S-28; Baker et al. 2008, p. 29; Donaldson 2008,
p. 3).
The State of Idaho implements several fishing regulations to manage
potential angler impacts in State waters. For most streams able to
support larger fish, bag limits are 2 fish greater than or equal to 40
centimeters (cm) (16 in) in length. In smaller streams, where BCT
typically do not exceed 30 cm (12 in), the general stream limit is 2
fish, and no size constraints exist. In other waters, seasonal angling
restrictions or catch-and-release-only regulations are implemented
(IDFG 2008, pp. 3, 19). In Utah, several fishing regulations protect
native cutthroat trout from overutilization. The State reduced trout
bag and possession limits from eight fish to four, and imposed short-
term fishing closures to protect native cutthroat trout (Donaldson
2008, p. 3). Wyoming implements angling restrictions, such as size
limits, reduced bag limits, and tackle restrictions to protect BCT
populations (WGFD 2008, p. 8). Many of Nevada's BCT populations occur
in remote areas, which provide protection from heavy fishing pressure
(Baker et al. 2008, p. 29). None of the four States considers angling,
under their current regulations, to be a threat to the subspecies.
Collection of BCT for scientific or educational purposes is
controlled by strict State permitting processes that prevent excessive
sampling throughout its range in Utah, Wyoming, Idaho, and Nevada.
Collection of fish tissue for genetic sampling is conducted by
nonlethal techniques (Rogers 2007, pp. 1-3).
Summary of Factor B
No commercial harvest of BCT currently occurs. Only recreational
angling could potentially result in overutilization. However, Utah,
Idaho, and Wyoming have special regulations
[[Page 52245]]
providing protection against over-harvest of BCT. Also, in our 2001 12-
month finding (66 FR 51362), we concluded that angler harvest did not
pose a significant threat to the continued existence of BCT, and we
know of no new information during development of this finding to change
this conclusion. Collection of BCT for scientific or educational
purposes is controlled by strict State permitting processes throughout
the range of the subspecies. Therefore, we conclude that the best
scientific and commercial information available indicates that
overutilization for commercial, recreational, scientific, or
educational purposes is not a significant threat to BCT now, or in the
foreseeable future.
Factor C. Disease or Predation
Disease
The BCT Conservation Team evaluated disease in the BCT status
report (May and Albeke 2005, pp. 11-12, 40-42). Diseases considered had
the potential to cause significant impacts to population health and
included, but were not limited to, whirling disease, infectious
pancreatic necrosis virus, and furunculosis. The BCT Conservation Team
assessed risks based on proximity of disease-causing pathogens and
their accessibility to a population. The majority of the populations
(63 percent) have limited risk because disease and pathogens are not
known to exist in the watershed, or a barrier blocks upstream fish
movement. In general, isolated populations have less risk of
catastrophic diseases. Fourteen populations (9 percent) are currently
known to be infected with one of the identified diseases (May and
Albeke 2005, pp. 40-41).
In recent years, whirling disease has become of great concern to
fishery managers in western States. Whirling disease is caused by the
nonnative myxosporean parasite, Myxobolus cerebralis. This parasite was
introduced to the United States from Europe in the 1950's and requires
two separate host organisms to complete its life cycle. Its essential
hosts are a salmonid fish and an aquatic worm, Tubifex tubifex.
Juvenile, sub-adult, and adult life stages of BCT have been shown to be
susceptible to whirling disease in the Logan River, and some Logan
River study sites exhibit a downward trend in BCT abundance (Budy et
al. 2005, pp. xi-xiii). Despite this, BCT in the Logan River
demonstrate high growth and survival rates and are generally in
relatively good health. Logan River tributaries are important refuges
from whirling disease-infected areas in the Logan mainstem (Budy et al.
2005, pp. xi-xiii). Tubifex tubifex is most abundant in areas of high
sedimentation, warmer water temperatures, and low dissolved oxygen.
Most populations of BCT occur in cold water stream habitats at high
elevations, where Tubifex tubifex is less likely to be abundant.
All four States have developed management activities to protect BCT
populations from whirling disease. Though whirling disease is known to
occur in some Nevada waters, it currently does not pose a threat to BCT
populations because it occurs at low levels among BCT populations (NDOW
2006, pp. S27). Regardless, Nevada is in the process of formalizing
protocols for BCT reintroductions and transplants relating to disease
certification and broodstock management (NDOW 2006, pp. S27, S32).
Idaho has outlined several strategies to protect BCT populations from
the negative effects of disease. Strategies include monitoring fish
populations for disease, prohibiting importation of fish and wildlife
that carry disease risk, and ensuring that stocking, translocation, and
propagation of fish do not contribute to the transmission or
introduction of diseases (IDFG 2008, p. 14). Utah has some of the most
stringent fish disease laws in the United States, which do not allow
the stocking of fish that test positive for whirling disease (Donaldson
2008, pp. 4-5). UDWR is studying the effects of whirling disease in a
portion of BCT occupied waters in Utah that have been infected
(Donaldson 2008, p. 4). Wyoming has a policy of not stocking fish that
test positive for Myxobolus cerebralis (WGFD 2008, p. 9).
Predation
Of the 153 conservation populations identified in the rangewide BCT
status report, 97 (63 percent) had no interaction with nonnative fish
and 56 (37 percent) were sympatric with nonnative fish (May and Albeke
2005, p. 31). All BCT conservation populations sympatric with nonnative
fish are located in the Bear River and Northern Bonneville GMUs. In
these GMUs, BCT can be replaced by nonnative trout, but the degree to
which predation is a factor in this replacement has not been well
documented (Holden et al. 1997, pp. 3-21). Although nonnative fish can
have negative effects on BCT in localized areas due to predation,
research in the Logan River drainage shows that it is possible for BCT
populations to persist in the presence of predacious nonnative fish
(Behnke 1992, p. 107; Budy et al. 2005, pp. xi-xiii).
Predation can affect BCT, mainly during early life stages, where
other predaceous fish occupy the same area (UDWR 2000b, p. 48). Utah
has implemented several management actions intended to alleviate
potential predation of BCT by nonnative trout, including: nonnative
removal/barrier installation projects; barring nonnative cutthroat
stocking in conservation drainages; increasing angler harvest limits
for brook trout in the Boulder and Uinta Mountains; and initiating
fisheries research work (Donaldson 2008, pp. 5-7). Nevada has virtually
eliminated threats to BCT from nonnative fish by utilizing barriers and
nonnative removal restoration projects (Baker et al. 2008, pp. 3-5;
NDOW 2006, p. S-27).
Similar to Utah, Idaho and Wyoming have enacted management actions
intended to alleviate potential predation of BCT by nonnative trout.
Idaho has discontinued stocking brook trout into native trout streams,
increased the daily limit for brook trout from 6 to 25, and removed or
suppressed nonnative trout species that compete with BCT (IDFG 2008,
pp. 6-7). Wyoming is monitoring BCT populations to ensure that
nonnative populations do not become established in new waters in the
Bear River drainage, have ceased stocking nonnative trout in waters
managed for BCT conservation populations, and have implemented
nonnative removal/barrier installation projects to control nonnative
fish in BCT habitat (Emmrich 2008, p. 2; WGFD 2008, p. 10).
Summary of Factor C
Only 14 (9 percent) BCT conservation populations are infected with
a significant disease, and no additional populations are at high risk
for infection (May and Albeke 2005, pp. 40-41). Therefore, we conclude
that the best scientific and commercial information available indicates
that neither whirling disease nor other disease organisms significantly
threaten BCT now, or in the foreseeable future.
Predation by nonnative fish, the primary source of predation on
young BCT, may have some effect on BCT populations in the Bear River
and Northern Bonneville GMUs. However, 63 percent of conservation
populations have no interactions with nonnative fish. Also, research
shows that it is possible for BCT populations to persist in the
presence of predacious nonnative fish (Behnke 1992, p. 107; Budy et al.
2005, pp. xi-xiii). State fish and wildlife agencies continue to
implement management actions intended to alleviate potential predation
of BCT by nonnative fish. At this time, we know of
[[Page 52246]]
no information that indicates to us that predation significantly
affects BCT now, or in the foreseeable future.
Factor D. Inadequacy of Existing Regulatory Mechanisms
The Act requires us to examine the adequacy of existing regulatory
mechanisms with respect to extant threats that place the subspecies in
danger of becoming either threatened or endangered. Regulatory
mechanisms affecting BCT fall into three general categories: angling,
land management, and water quantity.
Angling
The States of Utah, Idaho, Nevada, and Wyoming consider BCT a game
species, and each State has specific regulations regarding catching BCT
by angling. We concluded above that recreational angling is not a
significant threat to BCT, now or in the foreseeable future (see Factor
B).
Regulatory Mechanisms Involving Land Management
Numerous State and Federal laws and regulations help reduce adverse
effects of land management activities on BCT. Most habitat in
watersheds inhabited by BCT conservation populations is managed by
Federal land management agencies, primarily the USFS and BLM, and to a
limited extent the NPS. Federal laws that reduce impacts to BCT and
their habitats include the Clean Water Act, Federal Land Policy and
Management Act, National Forest Management Act, Wilderness Act, and
National Environmental Policy Act. Approximately 49 percent of all
occupied BCT habitat (including both sport fish and conservation
populations) occurs on lands managed by Federal agencies, and the USFS
manages the majority (May and Albeke 2005, p. 29). Of the 3,830 km
(2,380 mi) of occupied habitat, 1,867 km (1,160 mi) are under Federal
jurisdiction and the majority occur on National Forests (1,209 km (751
miles)) (May and Albeke 2005, p. 29); these figures include sport fish
populations because figures for conservation populations alone are not
available (see Table 2 below). BCT occur in a large geographic area
within the following National Forests: Bridger-Teton, Caribou-Targhee,
Dixie, Fishlake, Humboldt-Toiyabe, Uinta, and Wasatch-Cache. BCT occupy
11 km (7 mi) of land administered by the BLM, and 7 km (4.4 mi) managed
by the NPS. Approximately 657 km (408 mi) of occupied BCT habitat
occurs in wilderness areas managed by the USFS or BLM. Wilderness Areas
and National Parks provide an extra level of protection for BCT because
many land management activities are prohibited in them.
Table 2--BCT Occupied Land Ownership
[Numbers include areas occupied by both sport fish and conservation populations]
----------------------------------------------------------------------------------------------------------------
USFS and BLM
USFS BLM NPS Wilderness Non-federal Total
----------------------------------------------------------------------------------------------------------------
1,209 km........................ 11 km 7 km 657 km 2,603 km 3,830 km
(751 mi)........................ (7 mi) (4.4 mi) (408 mi) (1,618 mi) (2,380 mi)
----------------------------------------------------------------------------------------------------------------
U.S. Forest Service
The USFS Sensitive Species Policy in Forest Manual 2670 outlines
procedures for conserving sensitive species. The policy applies to
projects implemented under the 1982 National Forest Management Act
(NFMA). The range of the BCT is within USFS Region 4, where it is
designated a sensitive species by the USFS, and where the Forests have
Land and Resource Management Plans (LRMPs) developed under NFMA. The
USFS has proposed a revision to NFMA in 2008; it is likely that, if the
rule is finalized, LRMPs would be revised accordingly. The NFMA
revision would result in more strategic and less prescriptive LRMPs
that identify ecosystem-level desired conditions and provide management
objectives and guidelines for meeting desired conditions (Forsgren
2008, pp. 1-2). The LRMPs might provide species-specific direction for
special status species when broader, ecosystem-level desired conditions
do not meet conservation requirements.
USFS Manuals and Handbooks codify the agency's policy, practices,
and procedures and are sources of administrative direction for USFS
employees. USFS Region 4 applies practices outlined in their Soil and
Water Conservation Practices Handbook to BCT habitat (USFS 1988, pp. 1-
71). This handbook states that the USFS will apply watershed
conservation practices to sustain healthy soil, riparian, and aquatic
systems. The handbook provides Management Measures with specific
criteria for implementation. For example, Management Measure No. 11.01
states: ``The Northern and Intermountain Regions will manage watersheds
to avoid irreversible effects on the soil resource and to produce water
of quality and quantity sufficient to maintain beneficial uses in
compliance with State Water Quality Standards.'' Irreversible effects
include reduced natural woody debris, excess sediment production that
could reduce fish habitat, water temperature and nutrient increases
that could affect beneficial uses, and compacted or disturbed soils
that could cause site productivity loss and increased soil erosion.
USFS land management practices are intended to avoid these effects
whenever possible, while also providing for multiple-use mandates;
therefore, maintaining or enhancing BCT habitat is being considered in
conjunction with other agency priorities. We determined that USFS BCT
management policies are currently adequately reducing impacts to the
species; we found no information indicating that threats would rise to
a significant level in the foreseeable future.
Bureau of Land Management
The BCT is designated a sensitive species by the BLM in Utah,
Wyoming, Nevada, and Idaho. BLM policy offers the same level of
protection for sensitive species as for candidate species. The policy
in BLM Manual 6840--Special Status Species Management (BLM 2001, pp.
06A3-.06C1), reads as follows: ``For candidate/sensitive species where
lands administered by the BLM or BLM authorized actions have a
significant effect on their status, manage the habitat to conserve the
species by:
(a) Ensuring candidate/sensitive species are appropriately
considered in land use plans.
(b) Developing, cooperating with, and implementing range-wide or
site-specific management plans, conservation strategies, and
assessments for candidate/sensitive species that include specific
habitat and population management objectives designed for
[[Page 52247]]
conservation, as well as management strategies necessary to meet those
objectives.
(c) Ensuring that BLM activities affecting the habitat of
candidate/sensitive species are carried out in a manner that is
consistent with objectives for managing those species.
(d) Monitoring populations and habitats of candidate/sensitive
species to determine whether management objectives are being met.''
BLM land management practices are intended to avoid negative
effects to species whenever possible, while also providing for
multiple-use mandates; therefore, maintaining or enhancing BCT habitat
is being considered in conjunction with other agency priorities. We
find that BLM BCT management policies are currently adequately reducing
impacts to the species; we found no information indicating that threats
would rise to a significant level in the foreseeable future.
National Park Service
When the Great Basin National Park (Park) was established in 1986,
management of southern Snake Mountain Range streams was transferred
from NDOW and the USFS to the NPS. The Park developed a Fisheries
Management Plan in 1999 that included goals of reintroducing BCT into
several area streams. In 1999, 40 km (24 mi) of stream habitat was
unoccupied; due to restoration activities, 7 BCT conservation
populations now exist in 20 km (12 mi) of streams in and near the Park
(Baker et al. 2008, pp. ii, 1). The Park will conduct long-term
monitoring on the BCT populations and habitat. Most BCT waters within
the Park are in remote, high-elevation locations where angling pressure
is very light (Baker et al. 2008, pp. ii, 1). Livestock grazing, timber
harvest, mining, and development do not occur in Great Basin National
Park. We find that NPS management policies are currently adequately
reducing impacts to the species; we found no information indicating
that threats would rise to a significant level in the foreseeable
future.
Regulatory Mechanisms Involving Water Quantity
Utah and Nevada control the implementation of instream flow
regulations in BCT habitat. In Utah, the recent legislative session
passed an instream flow bill (HB 117) that should benefit BCT by
allowing private entities, such as Trout Unlimited, to lease 10-year
water easements for instream flows (Donaldson 2008, p. 3). Wyoming has
approved instream flow rights on 17 stream segments encompassing 66 km
(41 mi) of BCT habitat (WGFD 2008, p. 8). We find that regulatory
mechanisms regarding water policy are currently adequately protecting
the species; we found no information indicating that threats would rise
to a significant level in the foreseeable future.
Conservation Actions
State and Federal agencies are implementing existing programs to
restore and enhance BCT habitat. The majority of the 153 conservation
populations (57 percent) have one or more restoration, conservation, or
management activities either completed or currently being implemented
within BCT habitat (May and Albeke 2005, p. 51). The WGFD adopted a
Strategic Habitat Plan in 2001 (WGFD 2008, p. 6); under this Plan,
habitat biologists work with landowners and land managers to manage
habitat on a watershed scale to provide benefits to both terrestrial
and aquatic wildlife resources. The States of Utah and Nevada have
conservation agreements and conservation strategies involving review of
BCT biology and monitoring of current subspecies status and potential
threat factors (NDOW 2006, pp. 1 to S-26; UBCTCT 2008, pp. 1-23; UDWR
2008a, pp. 1-41). The State of Idaho has a Management Plan for
Conservation of BCT in Idaho that provides conservation direction for
BCT (Teuscher and Capurso 2007, pp. 1-84).
The States of Utah, Nevada, Wyoming, and Idaho, and the USFS, BLM,
NPS, Service, Confederated Tribes of the Goshute Reservation, and Utah
Reclamation Mitigation and Conservation Commission are signatories to a
rangewide conservation agreement and strategy for BCT. This agreement
was implemented to ensure the long-term survival of the subspecies
through coordination of conservation efforts among the signatory
agencies (UDWR 2000b, pp. 1-90).
Numerous conservation actions have been planned and implemented
through State and Federal conservation and management plans. For
example, the State of Utah (where the majority of BCT habitat and
conservation populations exist) submitted two chronologies detailing
BCT conservation efforts over two different time frames. BCT
conservation actions were grouped from 1973-2001 (approximately 378
actions) and from 2001-2008 (approximately 355 actions); actions
included, for example, population surveys and monitoring, genetic
analysis, changes to angling regulations, broodstock development,
fencing of stream habitat, establishment of conservation easements,
nonnative fish removal and restocking with BCT, habitat surveys,
stocking policy changes, and general habitat enhancement projects (UDWR
2008b, entire). These chronologies show that conservation actions were
occurring prior to establishment of the State of Utah conservation
programs in 2000, and that the number of conservation activities
increased on a yearly basis (355 within 7 years) once these programs
were enacted. Additionally, the BCT Conservation Team submitted
information on State and Federal BCT conservation activities from 2001
through 2007 in Utah, Wyoming, Idaho, and Nevada; activities are
similar to those of the State of Utah described above (BCTCT 2008,
entire).
Under our Policy for Evaluation of Conservation Efforts When Making
Listing Decisions (PECE) (68 FR 15100; March 28, 2003), we typically
evaluate conservation efforts by State and local governments, and other
entities, that have been planned but not implemented, or implemented
but have not yet demonstrated effectiveness, in order to determine
which efforts meet the standard in PECE for contributing to our
finding. The actions described above were not analyzed using the PECE
standard because they were implemented prior to this review and their
effectiveness has been demonstrated by the general increases in BCT
population numbers (as discussed in the BCT Population Trend section).
State and Federal agency participation in BCT conservation plans is
voluntary; however, the States included in the range of the BCT have a
demonstrated history of effective management of the species. State
plans are typically in place indefinitely or have a term of agreement
for 5-10 years with renewal provisions for a similar time period. The
rangewide BCT conservation agreement was renewed in 2008 for 10 years,
with the commitment that it would be extended for an additional 10
years upon expiration. The success of the conservation actions, as
explained above, indicates that participating State and Federal
agencies are committed to the conservation of BCT, and the renewal of
the rangewide BCT agreement gives us a reasonable expectation that
these efforts will continue in the foreseeable future.
Summary of Factor D
We assessed the potential threats of livestock grazing, timber
harvest, roads, water management, mining, oil and gas developments,
angling, disease, and predation with regard to magnitude of impacts to
BCT, and to whether regulatory mechanisms are adequate.
[[Page 52248]]
We find that regulatory mechanisms related to land and fisheries
management are currently sufficient for mitigating potential threats to
BCT, and that the stable status of the species will continue in the
foreseeable future. The best scientific and commercial information
available indicates that existing regulatory mechanisms have maintained
or improved the status of BCT to the extent that listing under the Act
as a threatened or endangered species is not warranted.
Factor E. Other Natural or Manmade Factors Affecting the Species'
Continued Existence
Climate Change
The Intergovernmental Panel on Climate Change (IPCC) has concluded
that warming of climate is unequivocal (2007, p. 5), and that
temperature increase is widespread over the globe and is greater at
higher northern latitudes (IPCC 2007, p. 30). However, future changes
in temperature and precipitation will vary regionally and locally, with
some areas remaining unaffected or even decreasing in temperature (IPCC
2007, pp. 46-47). Changes in precipitation are less certain than in
temperature; climate models project more frequent heavy precipitation
events, separated by longer dry spells, especially in Utah and the
western United States (GBRAC 2007, p. A1, 14-15; IPCC 2007, p. 15).
During the past decade, the average temperature in Utah, like that
of much of the globe, was higher than observed during any comparable
period of the past century (IPCC 2007, pp. 31-32). As discussed below,
that increase in temperature, if permanent, does not constitute a
significant threat to the BCT. The remaining question is whether
possible future increases in temperature will constitute a threat. Over
the next 20 years, climate models estimate that the Earth's average
surface temperature will increase about 1.4 [deg]C (0.8 [deg]F).
Climate change predictions based on continental-scale analysis are
generally given ranking based on degree of certainty (IPCC 2007, p. 27;
GBRAC 2007, pp. 3-11). Utah is projected to warm more than the global
average (GBRAC 2007, pp. ES 2-3); however, levels of confidence in
projections for local-scale areas are lower than for projections at
global or continental scales, and are generally not given a degree of
certainty ranking (GBRAC 2007, pp. 17-20). Clear and robust future
trends have not been developed for Utah (GBRAC 2007, p. 2). We cannot
make reliable predictions about the magnitude or timing of future
temperature increases within the range of the BCT.
Based on the Utah Governor's Blue Ribbon Advisory Council on
Climate Change (2007), which is a regional study, climate change will
likely cause environmental changes in Utah, which could increase
challenges for BCT rangewide. According to some research, climate
change has already had or is predicted to have negative consequences on
coldwater fisheries globally (Nakano et al. 1996, p. 711; Hari et al.
2006, p. 24), and in the Southwest and Rocky Mountains of North America
(Keleher and Rahel 1996, p. 1; Rahel et al. 1996, pp. 101, 102, 113),
through increases in ground- and surface-water temperatures. Rahel et
al. (1996, p. 1116) and Keleher and Rahel (1996, p. 9) predicted that
elevationally diverse regions such as the Rocky Mountains will
experience warming stream temperatures that could restrict cold water
species, such as cutthroat trout, to increasingly higher elevations,
thus reducing the geographic range and occupied stream distance and
increasing habitat fragmentation. Keleher and Rahel (1996, p. 5)
calculated that in Wyoming a 1 [deg]C (1.8 [deg]F) increase in mean
July air temperatures could decrease the length of streams inhabitable
by salmonid fish by 8 percent; a 2 [deg]C (3.6 [deg]F) increase could
cause a reduction of 14 percent, a 3 [deg]C (5.4 [deg]F) increase could
cause a 21 percent decline, a 4 [deg]C (7.2 [deg]F) increase could
cause a 31 percent reduction, and a 5 [deg]C (9 [deg]F) increase could
cause a 43 percent reduction. In the Rocky Mountains, Keleher and Rahel
(1996, p. 5) calculated similarly high reductions of 16.8, 35.6, 49.8,
62.0, and 71.8 percent with respective temperature increases of 1, 2,
3, 4, or 5 [deg]C in July air temperatures. One study concluded that if
warming air temperatures occur, it will likely cause numerous
fundamental environmental changes, including increased stream and lake
temperatures, increased evaporation rates, reduced annual snowpack,
changes in river flows, and increases in disturbance events such as
floods, drought, and fire (Williams et al. 2007, p. 2).
However, even if temperatures within the range of the BCT increased
by the amounts considered in these studies, it would not put the
species in danger of extinction. Bonneville cutthroat trout may be able
to sustain viable populations at slightly warmer temperature conditions
than other cutthroat trout subspecies. For example, Williams et al.
(2007, p. 3) reported that less than 1 percent of the total
distribution of westslope cutthroat trout and Colorado River cutthroat
trout occurred in streams with an average July temperature greater than
22 [deg]C (71.6 [deg]F), but nearly 20 percent of the historical
distribution of Bonneville cutthroat trout was associated with a mean
July air temperature greater than 22 [deg]C (71.6 [deg]F). In addition,
Bonneville cutthroat trout appeared to be thermally distributed
bimodally, with two peaks. The warmer second peak occurred due to an
extensive network of lower elevation, warmer valley bottoms that were
historically occupied (Williams et al. 2007, p. 3). Bonneville
cutthroat trout have adapted to a broad spectrum of habitat conditions
throughout their range (Kershner 1995, p. 28).
Water temperature increases could result in a potential benefit to
Bonneville cutthroat trout in localized areas. Cold summer water
temperatures (mean July temperature of less than 7.8 [deg]C (46
[deg]F)) have been found as a limiting factor to recruitment of
cutthroat trout in high-elevation streams (Harig and Fausch 2002, p.
545; Coleman and Fausch 2007, pp. 1238-1240). Therefore, although
climate change is likely to increase water temperatures and result in a
reduction in habitat quality for lower elevation streams, some higher
elevation streams may become more suitable for BCT.
Declines in low-elevation mountain snowpack have been observed over
the past several decades in the Pacific Northwest and California.
However, no clear long-term snowpack trends are currently evident in
Utah's mountains (Hamlet et al. 2005, p. 4560; GBRAC 2007, pp. A1, 1-
2). Dates of peak snow accumulation and peak melt have also been
trending earlier, but with the most notable differences occurring in
coastal areas of the West that have warmer winter temperatures (Hamlet
et al. 2005, p. 4560). Stewart et al. (2005, p. 1152) indicate that
spring streamflow in the western United States during the last 5
decades has shifted so that the major peak now arrives 1 to 4 weeks
earlier, resulting in declining fractions of flow in the spring and
summer. However, streamflows in Utah and the Intermountain West do not
show clear trends over the past 50 years (GBRAC 2007, p. A1, 10).
In another study, three elements of environmental change expected
to affect Western cutthroat trout as a result of climate change
(increased summer water temperatures, flood events, and wildfire) were
modeled to determine where a particular subspecies is likely to be at
greatest risk (Williams et al. 2007, pp. 2-5). The three elements were
modeled individually, and then combined into a composite risk and
[[Page 52249]]
modeled jointly. Modeling showed that 43 percent of sub-watersheds with
existing BCT populations are at low or moderate risk from climate
change, and 57 percent are at high risk. The modeling also evaluated
BCT populations in regional areas. The composite analysis showed that
cutthroat populations in most of the Bear River basin and the eastern
portion of the Northern Bonneville basins are likely at low risk from
climate change, while the West Desert, Southern Bonneville, and
Northern Bonneville basins are in the moderate to high-risk range
(Williams et al. 2007, p. 6).
A recent status review (73 FR 27899; May 14, 2008) for the Rio
Grande cutthroat trout (Oncorhynchus clarkii virginalis) provided a
comprehensive review of potential global and regional climate change
effects to that subspecies. The status review provided detailed
information regarding the potential effects of temperature change,
decreased stream flow, change in hydrograph, and increases in extreme
events.
The Rio Grande cutthroat trout is native to the Rio Grande, Pecos,
and Canadian River basins in New Mexico and Colorado (Behnke 2002, p.
219); the northern extent of this subspecies' range lies at a more
southerly latitude than the range of the Bonneville cutthroat trout.
Therefore, predictions of the effects of climate change are likely to
differ to some extent between the subspecies. One of the effects of
climate change is that salmonid species are likely to be restricted to
increasingly higher elevations or to more northern latitudes (Meisner
et al. 1988, p. 6; Regier and Meisner 1990, p.11; Keleher and Rahel
1996, p. 2; Nakano et al. 1996, pp. 716, 717; Rahel et al. 1996, p.
1122; Poff et al. 2002, p. 7; Rieman et al. 2007, p. 1558). Coldwater
species occupying the southern distributions of their range, such as
the Rio Grande cutthroat trout, are seen as more susceptible to
extirpation as a consequence of global climate change (Poff et al.
2002, p. 8; Rieman et al. 2007, pp. 1552, 1553).
Because Rio Grande cutthroat trout primarily occupy high-elevation
headwater tributaries, dispersal to new habitats is unlikely because
they currently occupy the uppermost available habitat (73 FR 27899; May
14, 2008). In contrast, habitat for the Bonneville cutthroat trout is
widely distributed and variable, ranging from high-elevation (3,500 m
mean sea level) streams with coniferous and deciduous riparian trees to
low-elevation (1,000 m mean sea level) streams in sage-steppe
grasslands containing herbaceous riparian zones (Kerschner 1995; p.
28). BCT have adapted in order to survive in relatively warm water and
marginal habitats, and migratory life forms historically grew to be
quite large in lakes and large rivers. Some populations within the Bear
River drainage in southern Idaho and northern Utah continue to exhibit
the species' impressive range of life history strategies and habitat
requirements, migrating seasonally between turbid, lower elevation
mainstem rivers and cold, clear, high-elevation tributary streams
(Trout Unlimited 2008, entire).
Climate change biological projections are based on effects models
that have varying degrees of uncertainty (IPCC 2002, pp. 14-16). For
example, Williams et al. (2007, p. 6), in their modeling of climate
change and western trout, used a 3 [deg]C temperature increase
(projected for the U.S. Pacific Northwest in this century based on a
2004 University of Washington Climate Impacts Group). It is unknown
when the predicted 3 [deg]C raise in temperature might be realized.
Questions also remain regarding the projected extent of climate change
across regional areas, the timeframe for temperature and precipitation
changes, and the overall response of fish populations. It is unclear
how climate change will interact with other environmental stressors at
regional levels (IPCC 2002, p. 15).
While climate change is likely to affect aquatic resources to some
extent, including habitat utilized by BCT, at this time we find that
these effects are not likely to cause significant long-term impacts to
population viability. Current data indicate that the observed recent
effects of climate change have had little significant impact on BCT
population trends. BCT population trends show increasing numbers of
conservation populations and increases in the amount of occupied river
habitat, from 15 populations in 34 km (21 mi) of habitat in 1978, to
153 populations in 3,316 km (2,061 mi) in 2004 (May and Albeke 2005, p.
31; Hickman 1978, pp. 121-122). Therefore, although climate change may
cause some level of long-term effects to aquatic habitat, we find that
climate change is not currently a threat to BCT, which have adapted to
a broad spectrum of habitat conditions. We also find that climate
change is not likely to significantly threaten the species rangewide
within the foreseeable future.
Fragmentation and Isolation of Small BCT Populations in Headwater Areas
The majority of BCT conservation populations (101; 66 percent)
occur as isolated, non-networked populations (May and Albeke 2005, p.
34); 25 populations (16 percent) are weakly connected; 15 populations
(10 percent) are moderately connected; and 12 populations (8 percent)
have migratory forms and open migration corridors that make them
strongly connected. The strongly connected populations occur in Utah,
Idaho, and Wyoming in the Bear River and Northern Bonneville GMUs (May
and Albeke 2005, pp. 34, 107, 115, 117).
Cutthroat metapopulations are defined as a collection of localized
populations that are geographically distinct but genetically
interconnected through natural movement of individual fish between
populations (UDWR 2000a, p. 8). Metapopulations are important because
they maintain genetic exchange and increase genetic diversity. They
also provide individuals to repopulate stream segments where
populations are lost due to stochastic environmental events.
Metapopulations are important to the overall status of the subspecies,
but they are at a higher risk for disease and invasion of nonnative
fish because these elements can move into any connected populations
even if they are introduced into a single localized area.
Problems associated with small, isolated cutthroat trout
populations include increased risk of extirpation by catastrophic
events and loss of genetic exchange. Isolated populations can also
potentially be at risk of extirpation due to ongoing environmental
forces causing changes in attributes such as habitat size, pool
availability, or water temperatures. Several researchers have attempted
to determine which environmental factors contribute to successful
translocation efforts intended to augment isolated populations, and to
integrate environmental factors into assessments of stream viability
for cutthroat trout. Cold summer water temperature, narrow stream
widths, and lack of deep pools can limit successful translocations of
cutthroat trout (Harig and Fausch 2002, pp. 545-547). In high-elevation
streams, cold summer water temperatures can delay spawning and lack of
deep-water pools can limit overwinter survival. Modeling of these
stream variables indicates that occupied stream length is an even
better predictor of cutthroat trout abundance than stream temperatures;
small increases in habitat length (e.g., by barrier removal or
rewetting of a dewatered stream segment) can produce a
disproportionately greater increase in fish abundance, increasing
viability of isolated populations (Young et al. 2005, pp. 2405-2406).
A static model intended to describe the relationship between fish
abundance and habitat is a tool for managers
[[Page 52250]]
implementing cutthroat trout restoration projects (Hildebrand and
Kershner 2000, pp. 515-518). The model is especially useful in
evaluating potential installation of artificial barriers to protect
from nonnative fish invasion. Modeling indicated that a stream length
of 3 km (2 mi) is required to support a population of 1,000 fish; 8 km
(5 mi) supports 2,500 fish; and 17 km (10 mi) supports 5,000 fish. The
model is not applicable in all situations; it incorporates several
assumptions specifying that it is most relevant to isolated populations
in streams less than 7 meters wide, and that food availability and
habitat quality affect the relationship between fish abundance and
stream length occupied. The relevance of the model for reintroduction
and restoration of BCT populations should be carefully assessed, as
small, isolated cutthroat trout populations have persisted for many
years, e.g., above waterfalls or in desert basins. Lack of habitat to
sustain a large population does not necessarily mean that a population
is destined to go extinct (Hilderbrand and Kershner 2000, p. 517).
Specific criteria for viable population size has not been developed for
BCT.
Small, isolated populations are at greater risk from stochastic
events such as fire, floods, and drought. However, the widespread
geographic distribution of BCT conservation populations in numerous
individual populations mitigates the potential of future catastrophic
natural events to affect a large proportion of the populations. It is
unlikely that a sufficient number of populations would be lost to
affect the overall status of the subspecies.
Fisheries management agencies have the ability to maintain or
reestablish BCT populations in areas where they are partially impacted
or lost to natural catastrophic events. While not to be relied on for
species conservation, restoration and reintroduction can be employed as
tools in specific cases. For example, wildfire can present an
opportunity to eliminate nonnative fishes that occur in BCT habitat,
after which reestablishment of BCT can occur. BCT populations have been
established in burned-over streams previously only occupied by
nonnative trout, including Leeds Creek and South Ash Creek in the Pine
Valley Mountains, and Birch Creek, a tributary to the Sevier River
(Ottenbacher 2008, entire).
Active programs are in place to restore metapopulations, where
possible, within the historic range of BCT in Utah and Nevada
(Donaldson 2008, pp. 9-10; NDOW 2006, p. S-8). All GMUs currently have
networked populations (metapopulations), and the strongest and largest
networks occur in the Bear River and Northern Bonneville GMUs (May and
Albeke 2005, p. 34).
A population health evaluation was conducted for all BCT
conservation populations, based on four health indicators: Temporal
variability (based on stream length), population size, population
production potential (growth and survival rates), and population
connectivity (May and Albeke 2005, pp. 44-49). The health evaluation
indicated that 91 conservation populations (59 percent) occur in stream
reaches of less than 10 km (6 mi) (May and Albeke 2005, pp. 44-49).
Approximately 38 conservation populations (25 percent) occupy stream
reaches between 10 km (6 mi) and 31 km (19 mi), and 24 populations (16
percent) occupy stream reaches of 32 km (20 mi) or more. Conservation
populations include: 32 percent with at least 2,000 adult BCT; 25
percent with between 500 and 2,000 adult BCT; 22 percent with between
50 and 500 adult BCT; and 21 percent with fewer than 50 adult BCT.
Most of the conservation populations (81 percent) were moderately
healthy in terms of growth and survival (population production
potential), based on habitat quality, presence of nonnative trout,
disease risk, land uses, and recovery actions. Composite scores of
conservation population general health included: 7 percent high; 39
percent moderately high; 37 percent moderately low; and 17 percent low
(May and Albeke 2005, pp. 44-49). Low to moderately low composite
scores (54 percent of BCT conservation populations) were primarily a
result of the number of small, isolated populations. Even though most
populations (66 percent) are small and isolated, these populations are
found in a minority of the total BCT conservation population habitat;
70 percent of total habitat has BCT conservation populations that are
moderately or strongly connected. As is explained below, these isolated
populations have been incorporated into the BCT Conservation Team's
conservation strategies and allow for BCT conservation populations that
are less susceptible to introgression, disease, and competition from
nonnative fish.
The BCT Conservation Team developed two conservation strategies for
BCT conservation and management (May and Albeke 2005, p. iii). One
strategy emphasizes isolated populations because they are less
susceptible to introgression, disease, and competition from nonnative
fish. In addition, multiple populations distributed throughout a
watershed reduce risk because the simultaneous loss of all populations
within the watershed is unlikely. The other strategy emphasizes
preserving and restoring metapopulations to provide genetic exchange
and allow for larger populations. Within the current range of BCT, and
within each GMU, both isolated populations and metapopulations are
present, providing for success of both conservation strategies.
The best available information indicates that, while most BCT
conservation populations occur in small stream reaches (59 percent),
most have moderately healthy growth and survival rates (54 percent). In
addition, 70 percent of total habitat includes populations that are
moderately or strongly connected. Therefore, we find that BCT
conservation populations are adequately healthy and will remain so in
the foreseeable future.
Nonnative Fishes
Introduced nonnative fish are a potential threat to native
cutthroat subspecies (UDWR 2000a, pp. 1-9; May and Albeke 2005, pp. 21-
24). We address this potential threat factor by breaking it into three
components: (1) Management practices that included stocking of
nonnative fish; (2) competition of nonnative fish with BCT; and (3)
hybridization of BCT with nonnative fish. We summarize all three of
these components together in the summary of Factor E because they are
interrelated.
Fisheries Management
Since the late 1800s, early pioneers and fisheries managers have
implemented fish stocking programs that introduced nonnative salmonids
into lake and stream habitats of BCT. Brook trout were introduced into
waters in Utah as early as 1875, rainbow trout in 1883, and brown trout
(Salmo trutta) possibly as early as 1895 (Popov and Low 1950, pp. 49-
57; Sigler and Miller 1963, pp. 29-54). It is unknown exactly when
nonnative cutthroat were introduced; in 1899, 11,000 adults and
yearling cutthroat trout were sent to the Fish and Game Warden in Salt
Lake City (Ravenel 1900, pp. 35-118). This delivery may have included
several subspecies, including Yellowstone cutthroat trout (Sigler and
Miller 1963, pp. 29-54). The earliest stocking records indicate large
numbers of young nonnative fish were stocked for decades into
accessible waters in an effort to restore or sustain a high-quality
fishery (Holden et al. 1997, pp. 2-1 to 2-13).
[[Page 52251]]
In 1915, nearly 2 million cutthroat and more than 7 million other
trout were planted in Utah waters alone within the Bonneville Basin
(Cope 1955, pp. 89-93). Of the cutthroat stocked in 1915, 100,000 were
from Utah, and the remainder were collected from Bear Lake and other
productive cutthroat populations and stocked into less productive or
exploited systems. From 1915 to 1952, more than 100 million cutthroat
were planted, comprising about one-third of the total stocking effort
in Utah; approximately 45 percent were imported from Utah, almost
exclusively from Yellowstone Lake (Cope 1955, pp. 89-93, as reported
from biennial Utah State Fish and Game Commission reports 1915-1952).
Comprehensive stocking records from the turn of the century for the
Bonneville Basin in Nevada, Idaho, and Wyoming are not readily
available because most of these peripheral areas of the Bonneville
Basin are remote and inaccessible. However, it has been suggested that
settlers moved fish among drainages in remote areas like the Snake
Valley and the Pine Valley Mountains in the mid-to late-1800s (Miller
and Alcorn 1946, pp. 173 193; Popov and Low 1950, pp. 38-39; Behnke
1992, pp. 134-135). Fish transplanting among and across drainages,
without oversight, consent, or record-keeping, was likely common in
remote pioneer settlements.
Although many nonnative species were once stocked throughout Utah,
salmonid species, particularly rainbow trout, Yellowstone cutthroat
trout, and brook trout, comprise the greatest potential threat to BCT.
Rainbow and Yellowstone cutthroat trout can interbreed with BCT (Busack
and Gall 1981, pp. 948-950; Weigel et al. 2002, pp. 397-401), and brook
trout can be a competitor for food sources (Peterson et al. 2004, p.
769) (see next section on Competition). Rainbow trout were regularly
stocked into most cold, clear-water stream systems and impoundments
throughout the Bonneville Basin (Duff 1988, pp. 121-127; Holden et al.
1997, pp. 2-5 to 2-13). Rainbow trout were commonly stocked at
accessible sites, which was not always successful in establishing wild
populations (those that naturally reproduce and recruit in the wild).
As a result, annual stocking was necessary to maintain a sustainable
fishery. Heavy annual stocking has taken place in some streams for more
than a century. In the past 30 years, stocking was modified to prevent
introduction of nonnative salmonids into waters with known pure
populations of BCT in Utah (Holden et al. 1997, pp. 2-13 to 2-22).
Because of the nearby source of fry in Yellowstone Lake,
Yellowstone cutthroat trout were readily available for stocking.
Yellowstone and other subspecies of cutthroat trout were stocked into
streams to supplement the declining native fishery. In some cases,
(e.g., Bear Lake) substantial records exist of annual stocking of
Yellowstone cutthroat trout and other species. Despite this stocking,
Yellowstone cutthroat trout did not necessarily become established in
all waters into which they were stocked, and BCT in some areas have
resisted hybridization with and replacement by nonnative trout (e.g.,
Bear Lake) (Behnke 1992, p 137). Genetic information is not currently
sufficient to clearly discern Yellowstone cutthroat trout from BCT in
the Bear River drainage because of their recent evolutionary
divergence; however, morphological characteristics are distinctive
between BCT and Yellowstone cutthroat trout and can be used to
determine hybridization where it is suspected (Behnke 1992, pp. 132-
138; Shiozawa 2008, p. 1).
State fish and wildlife agencies no longer stock nonnative trout in
BCT habitat, and are implementing strategies to minimize impacts to BCT
from nonnatives, such as installing fish barriers, removing nonnative
fish, and increasing nonnative fish bag limits.
Competition From Nonnative Fish
Nonnative trout are known to compete with BCT (Behnke 1992, p. 54).
Brown trout can successfully compete with BCT (Budy et al. 2005, pp.
xi-xiii), and brook trout can displace cutthroat trout when they occur
in the same habitat (Peterson et al. 2004, p. 769). Nonnative fish are
sympatric with BCT within currently occupied habitat in the four GMUs
(May and Albeke 2005, pp. 27-28). Currently occupied BCT habitat
includes 37 percent (1,365 km/848 mi) without nonnative fish, and 63
percent (2,466 km/1,532 mi) with nonnative fish. The majority of
habitat with nonnative fish is in the Bear River (1,398 km/869 mi) and
Northern Bonneville (1,024 km/636 mi) GMUs. Only 45 km (28 mi) in the
Southern Bonneville GMU have nonnative fish. No nonnative fish exist
within the West Desert GMU in BCT conservation population habitat.
BCT conservation populations represent approximately 87 percent of
currently occupied habitat (the other 13 percent includes sport fish)
(May and Albeke 2005, p. 31). Of the 153 BCT conservation populations,
97 (63 percent) have no interaction with nonnative fish, and 56 (37
percent) are sympatric with nonnative fish (May and Albeke 2005, p.
31).
Natural and human-made barriers protect some BCT populations from
competition with nonnative fish. Rangewide, barriers assist in
protecting 35 BCT conservation populations occupying 480 km (298 mi) of
stream (Burnett 2008b, pp. 1- Barriers help protect populations from
nonnative fish invasion, but negative effects, such as blocking fish
movement and fragmenting habitat, should be assessed and balanced
before installing barriers. Therefore, this strategy for managing
nonnative fish is not appropriate for all native cutthroat populations.
Hybridization With Nonnative Fishes
The scientific criteria for describing and formally recognizing
taxonomic species of fish are based almost entirely on morphological
characters (Behnke 1992, pp. 7-11). The advent of molecular genetic
techniques in the mid-1960s added an additional set of biological
markers that are used to distinguish species and subspecies of native
trout in the western United States. Most genetic analyses on native
cutthroat trout have confirmed the evolutionary distinctness among
species and subspecies that had been described taxonomically on the
basis of morphology (Behnke 1992, pp. 7-11).
Cutthroat trout populations that are less than 10 percent
introgressed with nonnative species (or other cutthroat subspecies)
retain morphological, behavioral, and ecological characteristics of
their nonintrogressed ancestors (UDWR 2000a, pp. 1-9). Individuals of a
particular cutthroat trout subspecies can possess nuclear genes from
another taxon, detectable only by molecular genetic techniques, while
still conforming morphologically, behaviorally, and ecologically to the
scientific taxonomic description of the parental native species (Busack
and Gall 1981, pp. 948-950; Weigel et al. 2002, pp. 397-401).
We do not consider populations or individual fish conforming
morphologically to the scientific taxonomic description of BCT to be a
hybridization threat to BCT. Although such individuals may have a low
frequency of genes from another taxon (less than 10 percent), we have
found no information indicating that such individuals express
behavioral, ecological, or life-history characteristics differently
than BCT native to a particular geographic area. The frequency of genes
from other taxons will likely remain low in BCT populations for several
reasons: (1) In
[[Page 52252]]
some locations BCT likely can have an ecological advantage over
nonnative fish because they have adapted over long time periods to
their specific habitat; (2) stocking of nonnative trout in BCT habitat
is no longer practiced by fish and wildlife agencies; and (3) 61
percent of BCT conservation populations are isolated by human-caused or
natural barriers, protecting them from increasing numbers of nonnative
trout (May and Albeke 2005, p. 37).
Some introgressed populations may be valuable to the overall
conservation and survival of a species or subspecies (Campton and
Kaeding 2005, pp. 1323-1324; USFWS 2003, pp. 46992-46993), because they
can still express important behavioral, life history, or ecological
adaptations of the indigenous population within a particular geographic
area. BCT have evolved in varying environmental conditions in differing
habitats across its range, and these conditions have likely influenced
its behavioral and life history traits. For example, BCT with fluvial
and adfluvial life-history strategies migrate up small streams to
spawn, and BCT with a resident life-history strategy are able to
conduct their entire life history (spawning, nursery/rearing, adult
stage including overwintering) in headwater tributaries that provide
all necessary life-history habitat types. Environmental conditions
particular to a specific BCT population's ecological setting (e.g.,
latitude, elevation, temperature and precipitation regime) may allow
for development of locally adapted traits that would justify
preservation of a partially introgressed population. Maintaining unique
life-history traits can outweigh the negative aspects of limited
introgression. Thus, agencies should carefully evaluate the long-term
conservation implications of strategies for managing introgressed BCT
populations within the range of the BCT (USFWS 2003, pp. 46992-46993;
Campton and Kaeding 2005, pp. 1323-1324), as different strategies may
be appropriate for different populations.
No standards exist that define exact thresholds for acceptable
levels of hybridization in cutthroat trout; however, we assessed all
relevant scientific and commercial information available in order to
arrive at generally applicable standards. These standards are
applicable to other species of cutthroat trout we have assessed,
including the Yellowstone (71 FR 8818, February 21, 2006) and Colorado
River (72 FR 32589, June 13, 2007) cutthroat trout subspecies. Similar
standards were applied to the Westslope cutthroat trout (WCT) (68 FR
46989, August 7, 2003); however, specific research was conducted
indicating that WCT 20-percent introgressed with rainbow trout were
indistinguishable morphologically from nonintrogressed WCT (Weigel et
al. 2002, pp.397-401). Species-specific research comparing
morphological characteristics to genetic introgression thresholds has
not been conducted on other cutthroat subspecies; therefore, we used
the more conservative threshold of 10 percent to define BCT
conservation populations.
When BCT are sympatric with rainbow trout and nonnative subspecies
of cutthroat trout, introgressed populations can occur, and because of
this, researchers have studied the genetic status of BCT. These studies
have measured levels of introgression in the BCT in targeted areas of
its range, but have not, additionally, measured the morphological
characteristics present at varying levels of introgression. The
rangewide status report includes a summary of BCT genetic status (May
and Albeke 2005, pp. 21-24).
Genetic testing was conducted in more than 784 km (487 mi) of BCT
occupied habitats (20 percent of occupied habitat) (May and Albeke
2005, pp. 21-24). This research was conducted specifically in
populations that appeared to be typical of the BCT phenotype; while
results help elucidate the level of introgression in BCT, they cannot
be used to summarize rangewide introgression levels. Test results
showed no evidence of introgression in samples from 611 km (411 mi) of
occupied habitat (17 percent of occupied habitat). An additional 1,215
km (755 mi) of occupied habitat (32 percent of occupied habitat) has
populations suspected to be genetically unaltered, based on the absence
of introduced hybridizing species and of stocking records for
hybridizing species. The BCT Coordination Team has classified these as
conservation populations. Hybridized fish occur in approximately 122 km
(76 mi) of stream habitat (4 percent of occupied habitat). An
additional 1,831 km (1,138 mi) of habitat (48 percent of occupied
habitat) contains fish that are potentially hybridized, based on the
presence of nonnative hybridizing species or records indicating past
stocking of nonnative hybridizing species.
Researchers also assessed the genetic contamination risk, based on
proximity and accessibility of rainbow trout and nonnative cutthroat
trout, for the 153 BCT conservation populations (May and Albeke 2005,
p. 37). A low genetic risk was found in BCT populations (94
populations; 61 percent) where a barrier provides complete blockage to
upstream fish movement of introduced hybridizing species. A moderately
low genetic risk was found in BCT populations greater than 10 km (6 mi)
from hybridizing species or subspecies, and a moderately high risk was
found in BCT populations within 10 km (6 mi) of hybridizing species or
subspecies (27 populations; 18 percent). A high risk rating was found
in BCT populations (32 populations; 21 percent) sympatric with
hybridizing species in the same stream segment. Of the populations that
were rated with low risk of genetic contamination, 87 (93 percent) were
identified as being isolated populations.
Summary of Nonnative Fishes
Despite the presence of nonnative fish species sympatric with BCT,
we find that stocking, competition, and hybridization do not pose
significant threats to BCT, because: (1) In some locations BCT likely
can have an ecological advantage over nonnative fish because they have
adapted over long time periods to their habitat; (2) well-distributed
core populations of BCT persist in streams with nonnative fish; (3) 61
percent of BCT populations are isolated from nonnative fish by natural
or constructed barriers; and (4) stocking of nonnative fish no longer
occurs in waters with BCT conservation populations. In addition,
programs are being implemented to remove nonnative trout, through
mechanical or chemical means, from BCT waters in all four States (NDOW
2006, p. S-22; IDFG 2008, pp. 9-10; Donaldson 2008, p. 5; WGFD 2008, p.
10). In Utah, between 2001 and 2007, nonnative fish removal was
conducted on more than 80 km (50 mi) of BCT streams (Donaldson 2008, p.
5).
Groundwater Pumping
Multiple filings for groundwater withdrawal from both the
carbonate-rock and alluvial aquifers in the Great Basin are currently
in place within the historic range of BCT populations in the West
Desert GMU. Southern Nevada Water Authority (SNWA) has applied to the
BLM for issuance of rights-of-way to construct and operate a system of
regional water supply and conveyance facilities. The project would
include conveyance of up to 24,384 hectares per meter (ha-m) (200,000
acre-feet per year (ac-ft)) of groundwater--20,360 ha-m (167,000 ac-ft)
by SNWA with the remaining capacity provided for Lincoln County Water
District from six hydrographic basins (SNWA 2007, p. 1-1). The
groundwater that SNWA intends to convey would be from both existing and
future permitted water rights in hydrographic basins of the Great Salt
Lake Desert Regional Flow System
[[Page 52253]]
(Nevada and Utah) and White River Flow System (Nevada).
SNWA's Groundwater Development (GWD) Project includes construction
and operation of groundwater production wells, water conveyance
facilities, and power facilities. The proposed production wells and
facilities would be located on public lands managed by BLM in Nevada.
No facilities are planned in Utah (SNWA 2007, p. 1-1).
The Nevada State Engineer issued a ruling on April 16, 2007,
approving a major portion of the SNWA groundwater rights applications
for the Spring Valley hydrographic basin. SNWA can pump 4,877 ha-m
(40,000 ac-ft) annually from the basin, with the potential for an
additional 2,438 ha-m (20,000 ac-ft) based on results of 10 years of
monitoring that will be conducted for the initial pumping allocation
(NSE 2007, p. 56). The Nevada State Engineer hearings on SNWA water
rights applications in Snake Valley are projected for fall 2009. In
addition to the water awarded to SNWA in Spring Valley, filings for
6251 ha-m (50,680 ac-ft) in Snake Valley are pending.
New, large-volume filings in the State of Utah include: Millville
Irrigation Co.--15172 ha-m (123,000 ac-ft) in Wah Wah Valley; the
Confederate Tribes of the Goshute Reservation--6168 ha-m (50,000 ac-ft)
in Deep Creek Valley; Central Iron County Water Conservancy District--
4564 ha-m (37,000 ac-ft) in Hamlin, Pine, and Wah Wah Valleys; private
parties in Snake Valley--1294 ha-m (10,490 ac-ft); and the State of
Utah School and Institutional Trust Lands--1105 ha-m (8960 ac-ft) in
Snake Valley (UGS 2008, entire). We did not receive information
detailing future plans for development on the filings of these Utah
water rights.
The SNWA GWD Project is anticipated to be completed and may begin
pumping in January 2014 (SNWA 2007, pp. 4-11). Prior to its completion,
baseline data collection and research on biologic and hydrologic
impacts will be completed and an intensive monitoring program will be
put in place to monitor and mitigate for Project effects. At the
present time, SNWA anticipates that ultimately between 110 and 200
groundwater production wells may be required for the GWD Project.
However, the specific locations of these wells are dependent upon
future rulings from the Nevada State Engineer, exploratory drilling
results, agency agreements, and results of actual groundwater pumping.
SNWA anticipates that it may take up to 20 years or more to site and
install all of the groundwater production wells for the project (SNWA
2007, p. 2-1).
A great deal of uncertainty exists regarding the long-term effects
of the groundwater pumping for aquifers and surface waters in the Great
Basin. However, well locations will generally be sited in valley
bottoms and be withdrawing water from deep carbonate and alluvial
aquifers. BCT populations are generally located in headwater streams in
the West Desert GMU, and it is anticipated that direct effects to BCT
populations and their habitat will be minimal or nonexistent.
Additionally, SNWA entered into a stipulation with the Department of
the Interior regarding SNWA's GWD Project water withdrawals in the
Spring Valley hydrographic basin. The goals of this stipulation include
avoidance of any effects to water-dependent ecosystems within the
boundaries of Great Basin National Park and avoidance of unreasonable
adverse impacts to water-dependent ecosystems in the remainder of the
project area. This will be accomplished through hydrologic and biologic
monitoring, management, and mitigation plans designed to identify,
avoid, and mitigate effects of groundwater withdrawal on dependent
ecosystems (SNWA 2008, p. 15).
It has been hypothesized that water development in two areas of the
GWD Project, the Spring Valley and Snake Valley Basins, could have
indirect effects to BCT habitats in the West Desert GMU. Groundwater
pumping could result in the lowering of valley water tables and spring
discharge rates and result in drying and desiccation of wetland and
riparian phreatophytic (deep rooted) vegetation. This could likely
result in an increase in fire frequency in Great Basin valley floors
that are adjacent to drainages that have BCT populations in headwater
streams. Riparian vegetation in drainages of the Snake and Deep Creek
ranges where BCT occur could become more susceptible to these fires.
However, there is a great deal of uncertainty as to whether this
scenario will occur or if it will have impacts to BCT as no information
exists regarding what the actual effects of pumping would be to valley
vegetation or fire frequency. At this time, we know of no information
that indicates to us that groundwater pumping in the West Desert GMU is
significantly affecting BCT now or into the foreseeable future.
Summary of Factor E
Despite the potential for increased risk to BCT populations
resulting from future climate change, we found no scientific and
commercial information leading us to conclude that climate change is
currently a significant threat to BCT conservation populations, or will
become so within the foreseeable future.
We assessed the potential risks to BCT conservation populations
associated with fragmentation and isolation of small BCT conservation
populations, including stochastic, catastrophic, natural events, and
find that they do not now, nor will in the foreseeable future,
significantly threaten the status of BCT to the extent that listing
under the Act as a threatened or endangered species is warranted.
We assessed the potential threats posed by nonnative species,
including historical stocking, competition, and introgressive
hybridization with rainbow trout or other cutthroat subspecies.
Nonnative fish species exist in 63 percent of occupied BCT habitat.
However, 61 percent of BCT populations are isolated from nonnative fish
by natural or constructed barriers, and stocking of nonnative fish no
longer occurs in BCT waters. These factors, combined with the current
distribution of conservation populations, indicate that nonnatives do
not currently affect the status of BCT to the extent that listing under
the Act as a threatened or endangered species is warranted. In
addition, management practices focused on removing and preventing
introduction of nonnative fish within BCT habitat, provide reasonable
assurance that this potential threat factor will not increase within
the foreseeable future.
Foreseeable Future
In the context of the Act, the term ``threatened species'' means
any species (or subspecies or, for vertebrates, distinct population
segments) that is likely to become an endangered species within the
foreseeable future throughout all or a significant portion of its
range. The term ``endangered species'' means any species that is in
danger of extinction throughout all or a significant portion of its
range. The Act does not define the term foreseeable future; however, we
consider it to be affected by the biological and demographic
characteristics of the species, as well as our ability to predict or
extrapolate the effects of threats facing the species in the future.
Quantification of the time period corresponding to the foreseeable
future is challenging because it necessitates making predictions about
inherently dynamic political, legal, and social mechanisms that
influence the degree and immediacy of potential threats to the species.
[[Page 52254]]
For the purpose of this finding, the ``foreseeable future'' is the
period of time over which events or effects reasonably can or should be
anticipated, or trends reasonably extrapolated, such that reliable
predictions can be made concerning the status of the species in the
future. Although we have found some threats to BCT are ongoing at low
levels and that various localized areas may be affected by specific
problem activities, as discussed in the Summary of Factors section, we
did not find any information to suggest that threats will rise to
levels that would significantly threaten BCT rangewide to the extent
that the species would warrant listing under the Act.
Although we did not find any information to allow us to reliably
predict that threats would increase significantly in the future,
predicting and managing for the effects of potential future threats
will be facilitated by the BCT conservation plans that are in place at
the State and rangewide level (see Conservation Actions section under
Factor D). Monitoring of BCT population numbers and habitat conditions
is included in the State and rangewide conservation plans and any
significant decreases in BCT populations or habitat conditions should
be identified and effectively mitigated by using the methods developed
in these conservation plans. State and Federal agency participation in
BCT conservation plans is voluntary; however, State plans are typically
in place indefinitely, or have a term of agreement for 5-10 years with
renewal provisions for a similar time period. The rangewide BCT
conservation agreement was renewed in 2008 for 10 years with the
commitment that it would be extended for an additional 10 years upon
expiration. In addition, the States within the range of the BCT have an
established record of managing for the species (see Factor D). We find
that the BCT conservation plans will be in place and operating for at
least 20 years. We consider the status of the BCT to be reasonably
predictable with established management practices in place because many
of the threats to the species are effectively mitigated by these
practices; outside the timeframe of the conservation plans, we are
unable to make reliable predictions regarding the threats to the
species and the effect of those threats on the status of the species.
Therefore, the foreseeable future for BCT is 20 years with respect to
most threats.
Our ability to predict the effects of future threats is limited to
our knowledge of the timeframe of the threats potentially facing the
BCT, and the conservation activities taking place to address them. We
assessed activities that could potentially affect BCT populations under
the Summary of Factors section. Livestock grazing was a concern in the
early 1900's, but recent management practices appear to have reduced
effects to watersheds, and these practices are expected to continue for
at least 20 years. Road construction or maintenance, timber harvest,
and water diversions and depletions are expected to be managed
consistently within at least the next 20 years, and are not expected to
result in a downward trend in BCT population status. The foreseeable
future for oil and gas development is possibly shorter than for other
threats (i.e., less than 20 years), because this threat is not
specifically mitigated by conservation actions identified in the State
conservation plans; however, oil and gas developments are mostly
outside the historic range of the BCT, and are not creating a downward
trend in population status. Recreational angling is currently
regulated, and no downward trend in population status exists due to
this activity. Disease in BCT is being mitigated through conservation
actions that are expected to continue for at least the next 20 years.
Factors related to the presence of nonnative fish species, such as
predation, competition, and genetic introgression, are being mitigated
through conservation actions that are expected to continue for at least
the next 20 years.
Climate change projections are considered fairly robust for the
current century on a continental scale, but, as discussed above, we
cannot yet make reliable predictions as to the magnitude or timing of
likely temperature increases within the range of the BCT. Therefore,
for the purposes of analyzing the threat of climate change to the BCT,
the future is only foreseeable to the extent of our determination that
some additional temperature increase is likely. We cannot determine
that the BCT will become endangered due to an unquantifiable amount of
temperature increase, particularly given the BCT's apparent
adaptability to a relatively broad spectrum of habitat conditions,
although we recognize that it is possible that climate change will
eventually have more significant impacts.
We have determined that the immediacy and magnitude of the above-
mentioned threats will not significantly degrade the 80 percent of BCT
habitat that is currently in fair to excellent condition within the
next 20 years, in part due to regulatory mechanisms and management
practices (no nonnative stocking, combined with nonnative removal
programs) that have been implemented and shown to be effective by State
and Federal management agencies, and that we have reasonable assurance
will continue for at least the next 20 years.
Significant Portion of the Range
As required by the Act, we considered the five potential threat
factors to assess whether the BCT is threatened or endangered
throughout all or a significant portion of its range. When considering
the listing status of a species, the first step in the analysis is to
determine whether the species is in danger of extinction throughout all
of its range. If this is the case, then we list the species in its
entirety. For instance, if the threats to a species are directly acting
on only a portion of its range, but they are at such a large scale that
they place the entire species in danger of extinction, we would list
the entire species.
Based on the best available scientific and commercial information
available addressing BCT distribution and potential threats, especially
the rangewide status report for BCT (May and Albeke 2005, entire), we
find that the BCT is not likely to become endangered in the foreseeable
future throughout all of its range.
On March 16, 2007, a formal opinion was issued by the Solicitor of
the Department of the Interior, ``The Meaning of `In Danger of
Extinction Throughout All or a Significant Portion of Its Range' ''
(DOI 2007). A portion of a species' range is significant if it is part
of the current range of the species and is important to the
conservation of the species because it contributes meaningfully to the
representation, resiliency, or redundancy of the species. The
contribution must be at a level such that its loss would result in a
decrease in the ability to conserve the species.
We evaluated the BCT throughout its current range to determine if
any portion is likely to become threatened or endangered within the
foreseeable future, and if so, whether that portion is important to the
conservation of the species because it contributes meaningfully to the
resiliency, representation, or redundancy of the species.
The range of a species can theoretically be divided into portions
in an infinite number of ways. However, there is no purpose in
analyzing portions of the range that are not reasonably likely to be
significant and threatened or endangered. To identify portions that
warrant further consideration, we determine whether
[[Page 52255]]
there is substantial information indicating that (i) the portions may
be significant and (ii) the species may be in danger of extinction
there or likely to become so within the foreseeable future. In
practice, a key part of this analysis is whether the threats are
geographically concentrated in some way. If the threats to the species
are essentially uniform throughout its range, no portion is likely to
warrant further consideration. Moreover, if any concentration of
threats applies only to portions of the range that are unimportant to
the conservation of the species, such portions will not warrant further
consideration.
If we identify portions of the range that warrant further
consideration, we determine whether the species is threatened or
endangered in any significant portion of its range. Depending on the
biology of the species, its range, and the threats it faces, it may be
more efficient to address the significance question first, or the
status question first. If we determine that a portion of the range is
not significant, we need not determine whether the species is
threatened or endangered there; similarly, if we determine that the
species is not threatened or endangered in a portion of its range, we
need not conduct significance analysis.
The concepts of ``resiliency,'' redundancy,'' and
``representation'' are indicators of the conservation value of portions
of the range. Resiliency of a species allows the species to recover
from periodic disturbance. A species will likely be more resilient if
large populations exist in high-quality habitat that is distributed
throughout the range of the species in such a way as to capture the
environmental variability found within the range of the species. It is
likely that the larger size of a population will help contribute to the
viability of the species overall. Therefore, a portion of the range of
a species may make a meaningful contribution to the resiliency of the
species if the area is relatively large and contains particularly high-
quality habitat or if its location or characteristics make it less
susceptible to certain threats than other portions of the range.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This does not
mean that any portion that provides redundancy is a significant portion
of the range of a species. The idea is to conserve enough areas of the
range such that random perturbations in the system act on only a few
populations. Therefore, each area must be examined based on whether
that area provides an increment of redundancy that is important to the
conservation of the species.
Adequate representation insures that the species' adaptive
capabilities are conserved. Specifically, the portion should be
evaluated to see how it contributes to the genetic diversity of the
species. The loss of genetically based diversity may substantially
reduce the ability of the species to respond and adapt to future
environmental changes. A peripheral population may contribute
meaningfully to representation if there is evidence that it provides
genetic diversity due to its location on the margin of the species'
habitat requirements.
We assessed threats at the watershed-based GMU level, because
standardized fish monitoring methods and BCT management methods are
watershed based. The four GMUs are geographically and hydrologically
distinct; they also delineate BCT populations in logical
biogeographical and taxonomic subgroups. Based on the best available
scientific and commercial information regarding the abundance of BCT,
and our assessment of threats to the species, throughout its current
range, we find that no individual GMU is likely to become threatened or
endangered in the foreseeable future because threats are evenly
distributed throughout the range of the species.
Further subdividing of BCT populations or habitat into smaller
portions than GMUs would require unscientific methodology. In addition,
smaller subdivisions of populations would not, individually, be
significant to the subspecies. We find that areas smaller than the GMU
would not meaningfully contribute to the resilience, redundancy, or
representation of the BCT. Losses of habitat or species from areas
smaller than the GMU level would not threaten the entire GMU, and a
sufficient number of GMUs exist to ensure species redundancy and
resiliency. No significant ecological differences exist at levels
smaller than the GMUs to affect representation of the subspecies.
Threats are similar in all four GMUs, and no individual GMU has threats
of a magnitude that the subspecies is threatened or endangered within
it. Therefore, we have determined that no significant portion of the
BCT range is in danger of extinction or likely to become so within the
foreseeable future.
Distinct Vertebrate Population Segment (DPS)
Pursuant to section 4(a)(1) of the Act, we must determine whether
any species is an endangered species or a threatened species because of
any of the threat factors identified therein. Section 3(15) of the Act
defines ``species'' to include ``any species or subspecies of fish and
wildlife or plants, and any distinct vertebrate population segment of
fish or wildlife that interbreeds when mature'' (16 U.S.C. 1532 (16)).
To interpret and implement the distinct vertebrate population portion
of the definition of a species under the Act and congressional
guidance, the Service and the National Marine Fisheries Service (now
the National Oceanic and Atmospheric Administration--Fisheries)
published, on February 7, 1996, an interagency Policy Regarding the
Recognition of Distinct Vertebrate Population Segments under the Act
(DPS Policy; 61 FR 4722). The policy allows for more refined
application of the Act that better reflects the conservation needs of
the taxon being considered, and avoids the inclusion of entities that
may not warrant protection under the Act.
Under our DPS policy, three elements are considered in a decision
regarding the status of a possible DPS as endangered or threatened
under the Act. These are applied similarly for additions to the List of
Endangered and Threatened Wildlife and Plants, reclassification, and
removal from the List. They are: (1) Discreteness of the population
segment in relation to the remainder of the taxon; (2) the significance
of the population segment to the taxon to which it belongs; and (3) the
population segment's conservation status in relation to the Act's
standards for listing (i.e., whether the population segment is, when
treated as if it were a species, endangered or threatened).
Discreteness refers to the isolation of a population from other members
of the species and we evaluate this based on specific criteria. If a
population segment is considered discrete, we must consider whether the
discrete segment is ``significant'' to the taxon to which it belongs by
using the best available scientific information. If we determine that a
population segment is discrete and significant, we then evaluate it for
endangered or threatened status based on the Act's standards.
We assessed threats at the watershed-based GMU level, because
standardized fish monitoring methods and BCT management methods are
watershed based. The four GMUs are geographically and hydrologically
distinct; they also delineate BCT populations in logical
biogeographical and taxonomic subgroups. In addition, each GMU is
significant to the continued existence of the species. However, based
on the best available
[[Page 52256]]
scientific and commercial information regarding the abundance of BCT,
and our assessment of threats to the species, throughout its current
range, we find that no individual GMU is likely to become threatened or
endangered in the foreseeable future because threats are evenly
distributed throughout the range of the species.
The four GMUs meet the first two criteria in the DPS policy, but
the conservation status of each is stable. Further subdividing of BCT
populations or habitat into smaller portions than GMUs would require
unscientific methodology. In addition, while it is possible that
smaller units would meet the discreteness criteria in the DPS policy,
it is unlikely that any smaller area would be significant to the
subspecies.
Finding
This status review includes substantial information that was not
available at the time of the 2001 status review and 12-month finding
(66 FR 51362), in particular, the information obtained from May and
Albeke (2005). We requested a peer review of May and Albeke (2005);
peer reviews were conducted by five recognized cutthroat trout experts
who found that the document provided sound scientific data on the
rangewide status of BCT.
Populations of BCT have been greatly reduced over the last 200
years, with much loss occurring in the late 19th and early 20th century
(Behnke 1992, pp. 132-138). However, recent surveys have shown that the
numbers of BCT populations have increased in the last 3 decades and the
subspecies remains widely distributed throughout a large geographic
area. We attribute the historic decline in the distribution of BCT to
the introduction of nonnative sport fish into BCT habitat that began in
the late 1800s. The wide distribution of rainbow trout and nonnative
cutthroat trout caused problems through competition, hybridization, and
predation. In some places, introduced fish expanded and colonized new
habitat, and formed naturally reproducing populations that occupy the
former, and in some cases current, range of BCT.
We found no evidence of continuing declines in the overall
distribution or abundance of BCT during the last several decades. A
substantial increase in the number of known populations has been
documented (May and Albeke 2005, pp. 63-64), and habitat quality is
good to excellent in over half (52 percent) of BCT habitat, and fair to
excellent in 80 percent of BCT habitat. Management agencies have
focused on the protection and restoration of conservation populations
of BCT in all currently occupied watersheds. Additional focus is on
habitat restoration activities and fisheries management actions
designed to benefit BCT. Some recognized threats to BCT, such as
excessive harvest by anglers and stocking of nonnative fishes, are now
regulated or discontinued so that they no longer threaten the continued
existence of BCT. Conservation actions have resulted in improved
population levels in some areas (Ottenbacher 2008, entire).
At least 153 BCT conservation populations collectively occupy about
3,316 km (2,061 mi) of stream habitat in 22 watersheds (HUCs) in Utah,
Idaho, Nevada, and Wyoming. These populations qualify as conservation
populations of BCT under standards developed by the States that are
consistent with our assessment of best available science. Conservation
populations are distributed throughout the four GMUs within the
historic range of the BCT. Of the 153 conservation populations
identified by May and Albeke (2005, p. 31), about 71 (46 percent) are
core populations comprised of nonintrogressed BCT (greater than 99
percent genetic purity).
Hybridization, mostly with nonnative rainbow trout and nonnative
subspecies of cutthroat trout that have established self-sustaining
populations in many areas in the range of BCT, has historically been an
issue of management concern. However, current State management has
greatly reduced opportunities for further genetic introgression. States
continue to monitor introgression in BCT throughout its range. We find
that the limited presence of genetic material from other fish species
or subspecies (typically less than 10 percent) is not a threat to BCT
conservation populations. Populations or individual fish with a low
level of introgression are morphologically, ecologically, and
behaviorally indistinguishable from nonintrogressed (i.e., pure) BCT.
Slightly introgressed BCT populations, with low amounts of genetic
introgression detectable only by molecular genetic methods (i.e.,
conservation populations), are an important component of BCT
conservation. Genetically pure populations (71 core populations) are
distributed throughout the current range of BCT. State and Federal
agencies are implementing strategies and actions to protect BCT
populations from invasion of nonnative species or subspecies that may
interbreed with BCT.
Brook trout, brown trout, and rainbow trout compete with BCT where
they are sympatric. Managers are monitoring competition from nonnative
fish in BCT waters, and implementing ongoing management strategies and
actions to curtail it. However, 1,365 km (848 mi) of habitat occupied
by BCT conservation populations are free of nonnative trout.
The BCT persists as a widely distributed subspecies; 153
conservation populations exist throughout the historic range, and a
metapopulation structure exists in each GMU. Nonintrogressed BCT core
populations exist in habitats secure from nonnative trout and thus are
protected from potential hybridization throughout the subspecies'
historic range. Although distribution of BCT has been reduced from
historic levels (the subspecies now occupies about 35 percent of
historic habitat), the 2005 rangewide status report on BCT documented
the continued existence of conservation populations throughout its
current range, and that 80 percent of occupied habitat is in fair to
excellent condition.
We have thoroughly assessed the current status of BCT, the
mitigation of existing threats, and the existence of laws and
regulations that minimize adverse effects of land management and other
activities on BCT. We find that the magnitude and imminence of threats
do not indicate that the subspecies is in danger of extinction, or
likely to become endangered, throughout all or any significant portion
of its range, within the foreseeable future. Therefore, we find that
listing the BCT as a threatened or an endangered species under the Act
is not warranted at this time.
References Cited
A complete list of all references cited herein is available upon
request from the Utah Ecological Services Field Office (see ADDRESSES
section).
Author
The primary author of this document is the staff of the U.S. Fish
and Wildlife Service, Utah Ecological Services Field Office (see
ADDRESSES section).
Authority: The authority for this action is the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 29, 2008.
Kenneth Stansell,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. E8-20674 Filed 9-8-08; 8:45 am]
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