[Federal Register Volume 71, Number 34 (Tuesday, February 21, 2006)]
[Proposed Rules]
[Pages 8818-8831]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-1539]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; 12-Month Finding
for a Petition To List the Yellowstone Cutthroat Trout as Threatened
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 (USFWS), announce our
12-month finding for a petition to list the Yellowstone cutthroat trout
(YCT) (Oncorhynchus clarkii bouvieri) as a threatened species
throughout its range in the United States, pursuant to the Endangered
Species Act of 1973, as amended. After a thorough review of all
available scientific and commercial information, we find that listing
the YCT 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
ongoing conservation of this subspecies.
DATES: The finding in this document was made on February 14, 2006.
ADDRESSES: Data, information, comments, or questions regarding this
notice should be sent to U.S. Fish and Wildlife Service, 780 Creston
Hatchery Road, Kalispell, Montana 59901. The complete administrative
file for this finding is available for inspection, by appointment and
during normal business hours, at the above address. The petition
finding, the status review for YCT, related Federal Register notices,
the Court Order, and other pertinent information, may be obtained on
line at http://mountain-prairie.fws.gov/endspp/fish/YCT/.
FOR FURTHER INFORMATION CONTACT: The Montana Ecological Services Field
Office (see ADDRESSES), by telephone at (406) 758-6872, by facsimile at
(406) 758-6877, or by electronic mail at [email protected].
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (ESA) (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 any species is 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 ESA 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, i.e., requiring a subsequent
finding to be made within 12 months. Such 12-month findings must be
published in the Federal Register.
On August 18, 1998, we received a petition dated August 14, 1998,
to list the YCT as threatened, under the ESA, where it presently occurs
throughout its historic range. Petitioners were Biodiversity Legal
Foundation, the Alliance for the Wild Rockies, the Montana Ecosystems
Defense Council, and George Wuerthner.
Biology and Distribution
The YCT is 1 of about 13 named subspecies of cutthroat trout native
to interior regions of western North America (Behnke 1992, 2002).
Cutthroat trout owe their common name to the distinctive red or orange
slash mark that occurs just below both sides of the lower jaw. Aside
from distribution, morphological differences, particularly external
spotting patterns, may distinguish the various subspecies of cutthroat
trout (Behnke 1992). Adult YCT typically exhibit bright yellow, orange,
and red colors on their flanks and opercles, especially among males
during the spawning season. Characteristics of YCT that may be useful
in distinguishing this fish from the other subspecies of cutthroat
trout include a pattern of irregularly shaped spots on the body, with
few spots below the lateral line except near the tail; a unique number
of chromosomes; and other genetic and morphological traits that appear
to reflect a distinct evolutionary lineage (Behnke 1992).
Also among those 13 cutthroat trout subspecies is the fine-spotted
Snake River cutthroat trout (which Behnke [1992] referred to as
Oncorhynchus clarkii spp., but more recently referred to as
Oncorhynchus clarkii behnkei [Behnke 2002]). The natural range of the
fine-spotted Snake River cutthroat trout is principally in the western
portion of Wyoming and southeastern Idaho, almost entirely surrounded
by that of O. c. bouvieri (Behnke 1992). In their petition, the
petitioners considered the fine-spotted Snake River cutthroat trout a
morphological form (or morphotype) of YCT. Biochemical-genetic studies
have revealed very little genetic difference between the large-spotted
form of YCT and the fine-spotted cutthroat trout of the Snake River
basin (most recently, Mitton et al. 2006 in review, Novak et al. 2005).
As the common names indicate, the large-spotted YCT and fine-spotted
cutthroat trout are typically separable based primarily on the basis of
the sizes and patterns of spots on the sides of the body. The large-
spotted YCT has pronounced, medium to large spots that are round in
outline and moderate in number, whereas the spots of the fine-spotted
cutthroat trout are the smallest of any native trout in western North
America and so profuse they resemble ``a heavy sprinkling of ground
pepper'' (Behnke 1992). However, in areas of natural geographic
overlap, intergrades of the two forms with intermediate spotting
patterns are common (Novak et al. 2005).
For purposes of this review, we use the name YCT to represent both
of the closely related putative subspecies (Oncorhynchus clarkii
bouvieri and Oncorhynchus clarkii behnkei) and they are considered a
single entity (as petitioned) in our status review (USFWS 2006). We
refer to them collectively as YCT throughout this document.
Although not specifically documented with historical data, the
recent historic range of YCT is thought to have included waters of the
Snake River drainage (Columbia River basin) upstream from Shoshone
Falls, Idaho (River Mile 614.7), and those of the Yellowstone River
drainage (Missouri River basin) upstream from and including the Tongue
River, in eastern Montana (Behnke 1992). Historic range of YCT in the
Yellowstone River drainage thus includes large regions of northwest
Wyoming and southcentral Montana. Historic range in the Snake River
drainage includes large regions of the western portion of Wyoming,
southeast Idaho, and small parts of the northwest corner of Utah and
northeast corner of Nevada (Behnke 1992, Novak
[[Page 8819]]
et al. 2005). The transcontinental divide range of YCT in Montana and
Wyoming likely resulted from headwater connection. The range of YCT may
have once extended further downstream, but probably became isolated in
the headwaters of the Snake River following creation of Shoshone Falls
(between 30,000 and 60,000 years ago). Today, various YCT stocks remain
in the headwaters of the Snake and Yellowstone River drainages in
Montana, Wyoming, Idaho, Utah, and Nevada.
The distribution of YCT occurs in 40 watersheds that can be
delineated by 4th code Hydrologic Unit Code (HUC) boundaries. Those
HUCs generally equate to named watersheds. In this 12-month finding,
the term HUC and the word watershed are used more or less
interchangeably. Twenty-two of those HUCs are in the headwaters of the
Yellowstone River basin and 18 are in the Snake River basin headwaters.
Because the status of native fish species can often vary substantially
from drainage to drainage, based on the presence and degree of threats
and other factors, we believe it is appropriate to treat these 40
watersheds as separate but related entities in order to evaluate the
array of threats and status of the species. We will follow that
approach to describe many of the threats for YCT.
May et al. (2003) defined a conservation population, per the State
position paper on Genetic Considerations Associated with Cutthroat
Trout Management (Utah Division of Wildlife Resources 2000), as one
that is either genetically unaltered (i.e., core population) or one
that may be slightly introgressed due to past hybridization (typically
less than 10 percent) and having attributes worthy of conservation.
Hybridization is an important concern for YCT populations. For
hybridization to result in an introgressed population, it requires that
the nonnative species be introduced into or invade the YCT habitat,
that the two species then interbreed (i.e., ``hybridize''), and that
the resulting hybrids themselves survive and reproduce. If the F1
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.
We have adopted the States' standards and consider all core and
conservation populations, as defined under these standards and as
described by May et al. (2003) to be YCT for purposes of this 12-month
finding. Because the categories are nested, the term conservation
population includes the core populations, and we refer to the
collective as conservation populations in the remainder of this
document. Those conservation populations collectively occupied about 84
percent of the total habitat occupied by YCT (the rest are sport fish
populations that are not considered YCT conservation populations).
The YCT status assessment report (May et al. 2003), identified
10,220 kilometers (km) (6,352 miles [mi]) of stream habitat occupied by
195 separate YCT conservation populations. May et al. (2003) indicated,
based on professional judgment which was used to produce an estimate of
potentially suitable habitat, that YCT historically occupied about
28,014 km (17,407 mi) of habitat (mostly stream, but including some
lakes) in five States. More details of the estimated current and
historic distribution are found in the status review accompanying this
finding (USFWS 2006).
Previous Federal Actions
On February 23, 2001, we published a 90-day finding (66 FR 11244)
which found that the petition to list the YCT failed to present
substantial information indicating that listing the YCT may be
warranted. A complaint was filed in the U.S. District Court for the
District of Colorado on January 20, 2004, on the conclusion of this 90-
day finding. On December 17, 2004, the District Court of Colorado
(Judge Figa) ruled in favor of the plaintiffs and ordered the USFWS to
produce a 12-month finding for YCT. On February 14, 2005, the Court
clarified the order and attached a February 14, 2006, due date for the
USFWS to complete the 12-month finding. We published a notice reopening
the comment period for 60 days on August 31, 2005 (September 1, 2005;
70 FR 52059). The comment period closed on October 31, 2005.
Summary of Factors Affecting the Species
Section 4 of the ESA (16 U.S.C. 1533), and implementing regulations
at 50 CFR part 424, set forth procedures for adding species to the
Federal List of Endangered and Threatened Species. In making this
finding, information regarding the status and threats to this species
in relation to the five factors provided in section 4(a)(1) of the ESA
is summarized below.
We examined each of these factors as they relate to the current
distribution of YCT. In response to our 2000 and 2005 Federal Register
notices, we received comments and information on YCT from several State
fish and wildlife agencies, the U.S. Forest Service (USFS), private
citizens and organizations, the Shoshone-Bannock Tribes, and other
entities. Among the materials that we received, the most important was
a status assessment report for YCT (May et al. 2003). The May et al.
(2003) status assessment was a comprehensive document covering the
entire range of the YCT, coauthored by the USFS in conjunction with
fish and wildlife agencies of the States of Idaho, Montana, Wyoming,
Utah, and Nevada.
The YCT status assessment report (May et al. 2003) and the
comprehensive database that is the report's basis, along with other
supplemental submissions from the agencies and commentors, presented to
us the best scientific and commercial information available that
describes the present-day rangewide status of YCT in the United States.
To compile the information in the status report (May et al. 2003), 43
professional fishery biologists from 10 State, Federal, and Tribal
agencies and private firms met at 5 State workshops held across the
range of YCT, in 2000. At the workshops, the biologists submitted
essential information on the YCT in their particular geographic areas
of professional responsibility, according to standardized protocols.
In conducting our 12-month finding for YCT we considered all
scientific and commercial information on the status of YCT that we
received or acquired between the time of the initial petition (August
1998) and the time of the final preparation of this finding. However,
we relied mainly on the published and peer-reviewed documentation for
our conclusions. Our evaluations of the five factors to the YCT are
presented below.
We used the database of May et al. (2003) to examine certain
aspects of threats and distribution on a watershed by watershed (i.e.,
HUC by HUC) basis. In order to do so, we used the GIS layers provided
with the database (Hagener 2005). We overlaid the HUC boundaries on the
conservation population stream layer and recalculated the stream
lengths that fell within each HUC. Because there are slight
irregularities in some of the HUC boundaries relative to the stream
reaches, summarized results are close to, but may not exactly
replicate, totals given by May et al. (2003). However, the conclusions
we have drawn remain appropriate.
[[Page 8820]]
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of the Species' Habitat or Range
May et al. (2003) revealed that 59 percent of the habitat for
extant YCT populations (including both conservation populations and
sport fish populations) lies on lands administered by Federal agencies,
particularly the USFS; specifically the Shoshone, Bridger-Teton,
Caribou-Targhee, Bighorn, Custer, and Gallatin National Forests.
Moreover, many of the strongholds for YCT conservation populations
occur within roadless or wilderness areas or national parks, all of
which afford considerable protection to YCT habitat.
We are not aware of any comprehensive assessment of habitat status
or trend that has been conducted across the range of the YCT. An
extensive body of published literature exists on effects of man-caused
perturbations to coldwater salmonid habitat (see for example Beschta et
al. 1987; Chamberlin et al. 1991; Furniss et al. 1991; Meehan 1991;
Sedell and Everest 1991; Frissell 1993; Henjum et al. 1994; McIntosh et
al. 1994; Wissmar et al. 1994; U.S. Department of Agriculture and U.S.
Department of the Interior 1996; Gresswell 1999; Trombulak and Frissell
2000). This literature provides a record of the types of activities
that are most detrimental to fish habitat. It further documents the
physical processes that result from these activities to cause negative
impacts to coldwater salmonids such as the YCT. Declines in populations
of native salmonids may result from the combined effects of habitat
degradation and fragmentation, the blockage of migratory corridors,
declining water quality or quantity, angler harvest and poaching,
entrainment (process by which aquatic organisms are pulled through a
diversion or other device) into diversion channels and dams, introduced
nonnative species, or other impacts (USFWS 2002). Examples of specific
land and water management activities that depress salmonid populations
and degrade habitat include dams and other diversion structures, forest
management practices, livestock grazing, agriculture, agricultural
diversions, road construction and maintenance, mining, and urban and
rural development.
An important aspect of population demographics, which contributes
to changes in the range of the YCT as a whole, is the abundance within
individual populations. Since each population exists under a unique set
of habitat variables and threats, it is important to consider the trend
in individual populations as a potential indicator of the status of the
subspecies as a whole. Unfortunately, few if any populations have been
adequately monitored to provide quantitative indicators of the
population trend over the past several generations, due mostly to
logistical and financial considerations.
May et al. (2003) conducted a qualitative assessment of the
viability of each of the 195 conservation populations, based on a
ranking system where each isolet (a population isolated by physical
barriers or habitat limitations, typically in a headwater drainage) or
metapopulation (a set of local populations, among which there may be
gene flow and extinction and colonization) was ranked from low to high
for each of 4 population variables. The status assessment (May et al.
2003) concluded populations at high or moderately high risk occupied
only 11.2 percent of the range of YCT conservation populations and the
remaining 88.8 percent were estimated to be at low or moderately low
risk.
The analysis of risk by watershed, conducted by May et al. (2003),
is largely congruent with our analysis of occupancy and distribution
(USFWS 2006). In general, HUCs or watersheds with populations occupied
by few or scattered isolets are considered at greater risk, due
primarily to the high degree of isolation. The HUCs with large,
interconnected metapopulations are generally rated as being at lower
risk. May et al. (2003) asked the 43 scientists who conducted the
rankings to determine, for each stream segment, which of 4 categories
best described their existing knowledge of the demographic status
(primarily trend) of the population. The YCT conservation population in
each stream segment was classified as either: (1) Much reduced and
declining over the long term and/or at a fast rate; (2) reduced and
declining; (3) reduced from potential, but now fluctuating around
equilibrium; and, (4) increasing, or fluctuating around equilibrium and
near potential. Results of this analysis indicated that for the
Yellowstone River basin only about 17 percent of stream miles
classified as isolets and 4 percent of miles considered part of
metapopulations were classified in the two reduced and declining
categories. For the Snake River basin only about 20 percent of stream
miles classified as isolets and 24 percent of miles considered part of
metapopulations were classified in the two reduced and declining
categories.
While the above analysis is primarily a qualitative indicator of
population health, it does provide some insight into the overall status
of the habitat. If habitat was rapidly declining or failing, it stands
to reason that population status would follow a similar trend. We were
only partially able to quantitatively assess the threat that
destruction, modification, or curtailment of habitat may present to YCT
for this finding. In the YCT review developed by May et al. (2003), the
biologists who participated were able to identify potential risks to
habitat in several categories, and they indicated on a stream reach
basis whether certain land use impacts were present (known) or may be
present (possible). May et al. (2003) cautioned that the information
was too qualitative to link land use impacts to specific conservation
populations and that much of the input was speculative. However, they
concluded that even with those uncertainties, the information could
serve to heighten awareness of the possible influences of land uses on
YCT.
The YCT review (May et al. 2003) considered and evaluated land and
water use impacts to YCT in seven broad categories: (1) Dewatering
(presumably including other irrigation-related impacts such as
impediments to fish passage, entrainment, stream channel
destabilization, etc.); (2) mining (presumably including impacts such
as effects to water quality, including dispersal of toxic substances
and sedimentation); (3) range, i.e., livestock grazing (presumably
including riparian impacts, sedimentation, trampling, and other
effects); (4) non-angling recreation (primarily identified as impacts
from four-wheelers, ATVs, nondispersed campsites, recreational
developments such as ski hills and golf courses, etc.); (5) roads
(presumably related to a multitude of activities, such as logging,
transportation corridors, recreational access and including not only
roads, but also railroads and other utility networks); (6) timber
harvest (presumably commercial private and public logging activities as
well as other associated actions of forestry management); and, (7)
other (including significant impacts not captured in the above, each
identified in spatially-linked comments in the database to the location
where they occur).
In the process of identifying the land use impacts described above,
and linking them to specific stream segments associated with YCT
conservation populations, fishery professionals were asked to judge
whether each activity resulted in ``known,'' ``possible,'' or ``no''
impacts (May et al. 2003; see USFWS 2006 for
[[Page 8821]]
more detail). For the 195 designated conservation populations of YCT,
the most commonly identified land use impact believed to affect the
status and conservation of YCT was livestock grazing. Grazing was
identified as a known impact on 45 populations (23 percent of the total
number of conservation populations) and a possible impact on 97 others
(50 percent). Thus, May et al. (2003) concluded that livestock grazing
likely adversely affects nearly \3/4\ of the conservation populations
of YCT. Grazing was followed, in order of frequency of occurrence
identified as an impact, by roads (known impact on 33 populations and
suspected on 66 more); non-angling recreation such as camping, trail
riding, ATVs, etc. (known impact on 34 populations and suspected on 42
others); timber harvest (known impact on 31 populations and suspected
on 35 others); stream dewatering (known impact on 21 populations and
suspected on 40 others); and mining (known impact on 17 populations and
suspected on 8 others). This information assessed only the relative
frequency of these land use factors in affecting YCT populations; it
did not assess the severity of impacts on a population by population
basis (May et al. 2003). For example, while impacts from dispersed
recreation may be pervasive, recreational impacts are not likely to
severely affect YCT habitat to the extent that more intrusive uses such
as major water withdrawals or extensive mining activities might in a
given drainage.
An evaluation of the land and water use information by stream
segment (May et al. 2003) reveals watersheds (HUCs) that are likely to
experience higher magnitude of such impacts, based simply on the known
presence of such activities (USFWS 2006). Watersheds in the Yellowstone
River basin where grazing, roads, and timber harvest were considered to
affect large areas of habitat occupied by conservation populations of
YCT were in the Upper Yellowstone, Shields, and Upper Wind (May et al.
2003). Conversely, several HUCs were identified as having large areas
of conservation habitat with no known impacts. These typically include
wilderness, national park, or other highly protected areas. Watersheds
in the Yellowstone River basin that were identified as containing over
161 km (100 mi) of habitat occupied by conservation populations with no
known impacts were the Yellowstone Headwaters, Upper Yellowstone and
Shields. The Upper Yellowstone and Shields HUCs both contain
substantial habitat that is heavily impacted as well as major portions
that are relatively unimpacted by land and water management activities.
In the Snake River basin, areas where grazing, roads, dewatering
and timber harvest were considered to have known impacts on large areas
of habitat occupied by conservation populations of YCT were located in
nearly all HUCs, but were especially pervasive in the Greys-Hobock,
Palisades, Salt, Teton, and Blackfoot watersheds. The only HUC in the
Snake River basin identified as having over 161 km (100 mi) of
conservation habitat with no known impacts was the Snake River
Headwaters. This information is based on a very coarse analysis and
should be viewed as preliminary. In a planned 2006 update of the
database, the information linking habitat impacts to specific
watersheds is expected to be improved (Brad Shepard, Montana Fish,
Wildlife and Parks [MFWP], pers. comm. 2005).
As reported, mining impacts are not pervasive across the range of
the YCT, but in some instances where they occur they have been noted to
have particularly severe consequences to aquatic habitat (USFWS 2002).
The status assessment of May et al. (2003) indicated that known impacts
of mining on YCT were most widespread in the Yellowstone Headwaters and
Upper Yellowstone HUCs, as well as in the Gros Ventre, Palisades, Salt
and Blackfoot watersheds of the Snake River basin, where 24-113 km (15-
70 mi) of YCT conservation populations in each watershed are known to
have been impacted. Lemly (1999) described a particularly threatening
scenario in the Blackfoot River drainage of Idaho where very high
selenium concentrations were first discovered. A preliminary hazard
assessment indicated that waterborne selenium concentrations in the
Blackfoot River and 14 of its tributaries met or exceeded toxic
thresholds for fish. The selenium problem centers on surface disposal
of mine spoils. Compounding this problem is the presence of historic
tailings dumps, many of which are large (>10 million cubic meters [353
million cubic feet]) and contain a tremendous reservoir of selenium
that has the potential to be mobilized and introduced into aquatic
habitats (Lemly 1999). Continued expansion of phosphate mining is
anticipated in these watersheds, and large mineral leases are awaiting
development both on and off National Forest lands (Lemly 1999,
Christensen 2005). This may be a serious and evolving situation.
However, while selenium poisoning should not be minimized as a threat
to conservation populations of YCT in the Blackfoot and Salt River
watersheds, it remains a localized threat and would not be expected to
cause rangewide losses of YCT conservation populations.
Another localized threat occurs in the Teton River watershed, where
Koenig (2005) and Benjamin (2005) reported that YCT populations have
experienced precipitous declines in recent years. These declines are
hypothesized to be linked to poor recruitment. Koenig (2005)
investigated whether specific habitat attributes could be limiting
cutthroat fry recruitment and at which life stage a recruitment
bottleneck may be operating. His conclusions were that the number of
cutthroat fry is more likely limited by low seeding than by spawning
habitat availability. Koenig (2005) further concluded that low survival
of age-1 cutthroat trout may be attributable to competition with
introduced rainbow and brook trout for overwinter habitat. Benjamin
(2005) speculated that water shortages and stream dewatering have
played a major role in the decline of YCT in the Teton River basin.
In Idaho, the State manages approximately 292,000 hectares (722,000
acres) of Endowment lands. These lands include approximately 200 km
(124 mi) of perennial streams that Idaho Department of Fish and Game
(IDFG) has identified as providing habitat for the YCT (Caswell and
Huffaker 2005). The predominant use of these lands is livestock
grazing, though some timber harvest also occurs. Where timber harvest
occurs on those lands, the State of Idaho reports that the Department
strictly adheres to the rules and guidelines provided by Idaho's Forest
Practices Act (Caswell and Huffaker 2005).
There are substantial portions of the range where habitat threats
appear to be limited. Wichers (2005) reported that the upper
Yellowstone River above Yellowstone Lake appears not to be subject to
genetic or habitat threats, due largely to the remote wilderness
setting (see USFWS 2006 for additional discussion).
In Yellowstone National Park (YNP), of the approximately 3,132 km
(1,946 mi) of stream originally supporting resident or fluvial YCT
(mostly outside of the Yellowstone Lake and River drainage above the
Lower and Upper Falls), 65 percent (2,025 km [1,258 mi]) continue to
support nonintrogressed fish, and 35 percent (1,107 km [688 mi]) now
are home to fish hybridized to varying degrees with nonnative rainbow
trout (Lewis 2005).
In Utah and Nevada, the range of YCT is restricted to a few
headwater streams
[[Page 8822]]
in the lower Snake River portion of the range, specifically in the
Goose and Raft HUCs. Utah and Nevada are part of the Interstate
Yellowstone Cutthroat Trout Working Group. They participated in the YCT
status assessment (May et al. 2003), but they have not provided
specific comments for this status review (USFWS 2006) regarding updates
to status or distribution. The States of Idaho, Montana, and Wyoming
comprise approximately 98 percent of the range of YCT conservation
populations.
The Center for Biological Diversity (Greenwald 2005) submitted an
alternative analysis of the data presented in May et al. (2003).
According to Greenwald (2005), these results clearly indicate that
ongoing habitat degradation is threatening remaining YCT populations.
We refer the reader to our previous discussion of the limitations of
the data on known habitat impacts presented in May et al. (2003). In
contrast with the Center for Biological Diversity (Greenwald 2005), the
USFWS finds that the mere presence of an activity within a stream
segment that hosts a conservation population is not sufficient evidence
to conclude that the population is threatened. Additional parameters,
such as distribution and abundance, as well as recent trends must be
factored into an overall status determination. Otherwise, logic would
dictate that every species that comes in contact with managed
landscapes is threatened by those human influences. Such a conclusion
is not reasonable.
Summary of Factor A
In summary, populations of YCT that meet the State management
agency standards as conservation populations (i.e., those populations
we are considering YCT for purposes of this finding), are well-
distributed and relatively secure in at least nine HUCs (i.e.,
watersheds) in the central headwaters of their native range. In the
Yellowstone River basin, we find that populations in the HUCs of the
Yellowstone Headwaters (1,308 km [813 mi] of occupied habitat), Upper
Yellowstone (822 km [511 mi]), and Shields (653 km [406 mi]) form the
central core of the YCT range and these populations are well-
distributed (collectively providing 64 percent of the habitat occupied
by conservation populations in the Yellowstone River drainage). In the
Snake River basin, the central core of the range for the YCT
conservation populations also is located in the headwaters, along the
Continental Divide. The six strongest remaining conservation
populations of YCT in the Snake River basin are in Greys-Hobock (1,051
km [653 mi] of occupied habitat), Snake Headwaters (716 km [445 mi]),
Salt (694 km [431 mi]), Teton (644 km [400 mi]), Palisades (501 km [311
mi]), and Gros Ventre (414 km [257 mi]) watersheds. Conservation
populations in these HUCS are generally well-distributed (collectively
providing 68 percent of the habitat occupied by conservation
populations in the Snake River drainage).
As a result of the present information, and as discussed more
thoroughly in the status review (USFWS 2006), we conclude the best
scientific and commercial information available to us indicates that
present or threatened destruction, modification, or curtailment of
habitat or range has not affected the status of YCT to the extent that
listing under the ESA as a threatened or endangered species is
warranted at this time. Although YCT distribution has declined, perhaps
by more than 50 percent over the past 200 years (May et al. 2003), our
analysis indicates that YCT strongholds remain in at least three major
watersheds of the upper Yellowstone River basin and six major
watersheds of the upper Snake River basin. These nine HUCs collectively
form a solid basis for persistence of conservation populations of YCT.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
In the YCT status assessment (May et al. 2003) consideration was
given to the effects of angling on population status. Angling was
considered to have a known impact on 54 of 195 conservation populations
(28 percent) and a possible impact on 22 other populations. In total,
then, recreational angling was considered by May et al. (2003) to
impact up to about 40 percent of the 195 designated conservation
populations of YCT.
Our status review (USFWS 2006) revealed that each of the States and
the National Park Service have greatly restricted the angler harvest of
YCT. May et al. (2003) noted that restrictive angling regulations have
been implemented for YCT on waters comprising nearly half of the 195
designated conservation populations of YCT. In many regions, catch-and-
release is the only type of angling that is allowed (Caswell and
Huffaker 2005; Hagener 2005; Koel et al. 2005; Osborne 2005; Wyoming
Game and Fish Department [WGFD] 2005). However, catch-and-release
angling regulations are not essential to protecting YCT from excessive
harvest by anglers in all waters.
Although overfishing contributed to the decline of YCT in specific
locations in the past, overfishing or overcollection is not currently
perceived as a threat to YCT in Montana (Hagener 2005), Idaho (Caswell
and Huffaker 2005), or Wyoming (WGFD 2005). These activities are
tightly regulated and have become increasingly restrictive. Enforcement
of regulations pertaining to native fish is a priority. Extensive
education and signing efforts have been undertaken to help anglers
identify YCT and to encourage their support for YCT conservation
efforts (e.g., Hagener 2005). Collection of YCT for scientific and
educational purposes is regulated by State agencies and is allowed only
for valid, scientific purposes. Collection methods, locations, and
timing are stipulated as part of the conditions of the permits.
In YNP, in order to ensure that the native YCT populations within
the Park continue to persist into the foreseeable future even with a
high degree of angling pressure, the Park instituted a mandatory catch-
and-release regulation for cutthroat trout and other native park fish
species in 2001 (Lewis 2005). Recently, they have proposed liberalizing
harvest limits for nonnative species that exist in waters that also are
inhabited by native cutthroat trout (Lewis 2005).
Threats from legal recreational angling are easier to control
through regulatory actions than are threats from most land and water
management activities. Where legal angling is considered a risk,
restrictive regulations continue to be implemented, sometimes with
dramatic results. For instance, directed harvest on rainbow trout was
rapidly initiated in the South Fork Snake River, upon discovery that
the rainbow trout population was expanding and threatening the YCT
population (J. Fredericks in litt., IDFG, 2005).
Summary of Factor B
Although overfishing contributed to the decline of YCT in specific
locations in the past, overfishing or overcollection is not currently
perceived as a threat to YCT. Therefore, we conclude the best
scientific and commercial information available to us indicates that
overutilization for commercial, recreational, scientific, or
educational purposes has not affected the status of YCT to the extent
that listing under the ESA as a threatened or endangered species is
warranted.
[[Page 8823]]
Factor C. Disease or Predation
Disease
The risk of transmitting disease while relocating wild or hatchery
fish into new waters is addressed via policies and State statutes
(Caswell and Huffaker 2005; Hagener 2005; WGFD 2005). For example, in
Montana, policy requires that an environmental assessment be completed
for all introductions of a species into waters where the species is not
found. The environmental assessment process provides for evaluation of
impacts to resident native species and public review. Before fish are
relocated, fish from the donor source are inspected for the presence of
any pathogen that might preclude the transfer. Approval of all fish
transfers requires the approval of the Fisheries Division Administrator
after consultation with the Fish Health Committee. Reducing the risk of
amplifying or spreading disease by hatchery operations is considered
important (Hagener 2005).
All fish hatcheries (Federal, State, and private) typically undergo
annual fish health inspections as authorized by State statute. In
Montana, for example, all hatcheries are required to report the
presence of fish pathogens, and damages resulting from spread of
diseases can be collected from the violator. The Montana Fish Wildlife
and Parks (MFWP) has spent several million dollars during the past 10
years to upgrade and protect State hatchery water sources so that
whirling disease and other pathogenic organisms cannot get into
hatchery water supplies (Hagener 2005). Before any fish lot is stocked
from a State facility, it is inspected for the presence of disease.
Diseased fish cannot be stocked from State hatcheries. Because of the
possible introduction of fish pathogens, MFWP does not bring wild fish
into any of its salmonid hatcheries. Additionally, movement of fish
between salmonid hatcheries is prohibited except in extreme emergencies
and must be approved by the Fisheries Division Administrator and the
Fish Health Committee (Hagener 2005).
As part of this 12-month finding, we consider the threat that
diseases may pose to YCT. Except for whirling disease, the fish
pathogens that occur in the natural habitats of YCT are mainly benign
in wild populations and typically cause death only when the fish are
stressed by severe environmental conditions. Whirling disease is caused
by the exotic myxozoan parasite Myxobolus cerebralis. That microscopic
parasite was introduced to the eastern United States from Europe in the
1950s, and has since been found in many western States. Two separate
host organisms are necessary for completion of the parasite's life
cycle, a salmonid (i.e., salmon, trout, and their close relatives) fish
and a specific aquatic oligochaete worm (Tubifex tubifex).
Whirling disease has been identified in fish populations in 148
watersheds in Montana, including sites on upper Yellowstone River, in
the Shields River, and in the Clarks Fork of the Yellowstone where YCT
occur (Hagener 2005). To date, whirling disease has not been detected
in any wild YCT populations in Montana and has not been documented as
causing any impacts to Montana YCT populations. In Montana, actions
continue to be taken to prevent the spread of whirling disease and to
minimize the impact of this disease on native fish (Hagener 2005).
Whirling disease has been reported in wild YCT from Henrys Lake,
Teton River, South Fork Snake River, and Blackfoot River in Idaho
(Caswell and Huffaker 2005). It also has been documented in rainbow
trout populations in several of the watersheds occupied by YCT in close
proximity.
In Wyoming, the whirling disease parasite was first detected in
1996 on the South Fork Shoshone River with the infection suspected to
have originated from privately stocked fish ponds adjacent to the river
(WGFD 2005). Since that time, the organism has spread elsewhere
throughout portions of Wyoming (USFWS 2006). To date, WGFD has not
observed a population impact on YCT from whirling disease in State-
managed waters.
Whirling disease has been implicated in the decline of YCT in
Yellowstone Lake (Koel et al. 2005). The parasite Myxobolus cerebralis
was discovered in Yellowstone Lake in 1998, among juvenile and adult
cutthroat trout (Koel et al. in press 2006). Examination of specimens
obtained as gillnetting mortalities has since confirmed the presence of
the parasite throughout Yellowstone Lake, with highest prevalence
existing in the northern region of the lake, near known infected
streams. Although widespread presence of this harmful parasite in the
lake has been documented, it is encouraging that the prevalence of
parasitic spores in adult fish suggests some cutthroat trout are
surviving initial infection (Koel et al. 2005).
The impacts of whirling disease in YNP have been most severe in
Pelican Creek (Koel et al. 2005), where few wild-reared fry have been
observed in recent years (2001-2004). Cutthroat trout sentinel fry
exposures (i.e., experiments with caged fish) in this tributary have
indicated that over 90 percent of the fry were infected with the
parasite, with an average severity (by histological examination) of
greater than ``4'' on a scale of ``0'' (no infection) to ``5'' (most
severe infection; Koel et al. 2004). The spawning cutthroat trout
population of Pelican Creek, which in 1981 totaled nearly 30,000 fish
(Jones et al. 1982), has been essentially lost (Koel et al. 2005).
Angling in the Pelican Creek drainage was completely closed in 2004, in
an attempt to slow the dispersal of the whirling disease parasite to
other Park waters.
Although the whirling disease parasite continues to spread in many
waters of the western United States (Bartholomew and Reno 2002) and is
now widespread in portions of the habitat occupied by YCT, few
outbreaks of whirling disease in resident fishes have occurred (Caswell
and Huffaker 2005; Hagener 2005; WGFD 2005). Studies summarized by
Downing et al. (2002) indicated that presence of the whirling disease
parasite does not portend outbreaks of the disease in resident fishes.
For example, although 46 of 230 sites tested in Montana were positive
for the parasite, disease outbreaks were known to have occurred at only
6 of those sites. Downing et al. (2002) provided evidence that the
frequent absence of manifest symptoms of whirling disease in resident
trout, despite presence of the parasite, is due to complex interactions
among the timing and spatial locations of important host-fish life-
history events (e.g., spawning, fry emergence from stream gravels, and
early-life growth) and spatial and temporal variation in the occurrence
of the parasite itself. Only under specific conditions, which evidently
occur only in a small proportion of the locations where the parasite
has been found, are those interactions such that disease outbreaks
occur in resident fishes.
Studies conducted on various salmonids by Vincent (2002) confirmed
that YCT were moderately susceptible to whirling disease. All of the
cutthroat trout he tested (including YCT of both the large-spotted and
fine-spotted forms as well as westslope cutthroat trout [WCT]) were
found under captive experiments to show significantly lower average
infection intensity than all of six different rainbow trout strains.
The WCT were found in those tests to have significantly lower infection
rates than either of the YCT. We are unaware of any studies of the
susceptibility of the hybrids of rainbow trout and YCT to whirling
disease.
[[Page 8824]]
The YCT status assessment report (May et al. 2003) concluded that
the threats to extant YCT populations from diseases in general were
greater for the extensive YCT metapopulations than for the smaller YCT
populations that occur as isolets. The key assumption made in reaching
that conclusion was that because the ranges of individual
metapopulations were naturally much larger and encompassed habitats
more diverse than those of isolets, the probability that diseases may
be introduced and become established in YCT populations and spread
through migratory behavior was greater for metapopulations than isolets
(May et al. 2003).
Extensive research is continuing to determine the distribution of
whirling disease, the susceptibility of YCT and other fishes to
whirling disease, infection rates, and possible control measures
(Bartholomew and Wilson 2002). Although no means have been found to
eliminate the whirling disease parasite from streams and lakes, the
States have established statutes, policies, and protocols that help to
prevent the human-caused spread of extant pathogens and the
introduction of new pathogens. The available scientific information
specific to whirling disease thus indicates considerable variation in
the probable disease threat among individual YCT populations and
provides evidence that the disease is not a significant threat to the
majority of populations constituting YCT (see USFWS 2006 for more
detail).
Predation
The instances when predation by other fishes may negatively affect
extant YCT populations are thought to be fairly well distributed across
the range, but are not well documented. Some authors have identified
nonnative species as one of the greatest threats to cutthroat trout of
the intermountain West (see for example--Gresswell 1995; Kruse et al.
2000; Dunham et al. 2004). Predation, or other forms of interaction
with nonnative fish, threatens native YCT in both managed landscapes
and in some relatively secure unaltered habitats, including roadless
areas, wilderness areas, and national parks. Based on observations to
date, YCT that have the adfluvial or fluvial life history may be most
susceptible to the effects of predation by nonnative fishes.
Introduced brown trout are well established in much of the range of
YCT, occurring primarily in rivers and their larger tributaries, where
they likely compete for food and space and prey on cutthroat trout.
Elevated water temperatures may often favor brown trout, which are
adaptable to such conditions over native species like YCT.
Introductions of nonnative game fish such as brown trout also can be
detrimental due to the increased angling pressure they may attract,
which can result in the subsequent incidental catch and harvest of YCT.
The illegal introduction and subsequent establishment of a
reproducing lake trout population in Yellowstone Lake has had far-
reaching consequences and serves as a well-documented example of such
impacts in the range of YCT. With the recent invasions by lake trout
(and whirling disease), YNP is placing a high priority on preservation
and recovery of YCT, particularly in Yellowstone Lake. Introduced lake
trout have already resulted in the decline of cutthroat trout (Koel et
al. 2005) and the problem also may have consequences to the food web,
including impacts on grizzly bears and other consumers (Koel et al.
2005; Lewis 2005). Nonnative lake trout are not viewed as a suitable
ecological substitute for cutthroat trout in the Yellowstone Lake
system because they are inaccessible to most consumer species (Koel et
al. 2005). Lake trout tend to occupy greater depths within the lake
than do cutthroat trout. Lake trout remain within Yellowstone Lake at
all life stages and they do not typically enter tributary streams, as
do cutthroat trout.
Bioenergetics modeling suggests that an average-sized mature lake
trout in Yellowstone Lake will consume 41 cutthroat trout per year
(Ruzycki et al. 2003). Following the guidance of a lake trout expert
advisory panel (McIntyre 1995), the National Park Service initiated
gillnetting to determine the spatial and temporal distribution of lake
trout within Yellowstone Lake (Koel et al. 2005). The efforts have led
to a long-term lake trout removal program for the protection of the
cutthroat trout in this system (Mahony and Ruzycki 1997; Bigelow et al.
2003).
Lake trout densities in the West Thumb of Yellowstone Lake remain
high and pose an ongoing threat to the cutthroat trout (Koel et al.
2005). The goals of controlling lake trout and rehabilitating
historical cutthroat trout abundance in Yellowstone Lake are yet to be
achieved. Relatively low lake trout catch per unit effort and an annual
decrease in the size of sexually mature lake trout are indicators that
the removal program is exerting pressure on the lake trout population
(Koel et al. 2005).
The lake trout threat in Yellowstone Lake is relatively new, occurs
in a unique ecological setting, and involves a predaceous nonnative
fish species (lake trout) that has a limited history of sympatry with
YCT (due partly to the relative scarcity of natural adfluvial
populations of YCT). A similar set of circumstances occurs in nearly a
dozen large headwater lakes of the Columbia River basin, located mostly
in and around Glacier National Park. Introduced populations of lake
trout have become established there and have dramatically expanded in
sympatry with native bull trout (Salvelinus confluentus) and WCT in
recent years. The initial lake trout introduction in Flathead Lake
occurred about 100 years ago and to date cutthroat trout have not been
extirpated from the lakes in the Flathead River system, but major food
web perturbations have occurred (Spencer et al. 1991). Some populations
of native fish persist only at very low levels (Fredenberg 2002). We
believe there is a level of uncertainty over the eventual outcome of
the competitive interaction between lake trout and YCT in Yellowstone
Lake. The USFWS finds reason for concern over the future of the
Yellowstone Lake population of YCT, and we will monitor this situation
closely. However, given the large scope of the Yellowstone Lake
ecosystem and ongoing conservation actions, we believe that
conservation populations of YCT will persist in this ecosystem, at
least for the foreseeable future.
We concur with Greenwald (2005), who submitted comments that
asserted: ``Where YCT are able to persist in sympatry with nonnative
trout, their overall numbers and biomass may be greatly reduced. This
is very likely a major factor, along with habitat degradation, in the
restriction of the YCT to isolated, high-elevation, headwater
streams.'' Greenwald (2005) noted that May et al. (2003) did not
compile data on the presence of non-hybridizing trout in YCT streams
(e.g., brown trout, brook trout), but concluded it is safe to say that
many of their conservation populations and the nonintrogressed
populations are in fact sympatric with nonnative trout. Greenwald
(2005) advocated that YCT populations existing in sympatry with
predaceous nonnative fish were not secure and are in fact, threatened
with extirpation. Nonnative trout that do not hybridize with cutthroat
have undoubtedly caused historical reductions in the size and
distribution of conservation populations of YCT across substantial
portions of the range. However, most of these introduced trout
populations have been in place for many decades, if not a century or
more, and they have not caused widespread
[[Page 8825]]
extirpation of YCT. Nonetheless, active programs to suppress or remove
nonnative trout from waters where YCT populations exist are encouraged
and in some areas are being initiated (USFWS 2006).
Summary of Factor C
As a result of this analysis, we conclude the best scientific and
commercial information available to us indicates that neither whirling
disease nor other nonnative disease organisms have affected the status
of YCT to the extent that listing under the ESA as a threatened or
endangered species is warranted at this time. Additionally, we conclude
the best scientific and commercial information available to us
indicates that predation from brown trout, lake trout, or other
predaceous, nonnative fishes has not affected the status of YCT to the
extent that listing under the ESA as a threatened or endangered species
is warranted. However, where such predation does occur, often on YCT
that have either the fluvial or adfluvial life history, it can have
serious consequences to conservation populations. The impacts of some
remaining, nonnative fishes overlapping with YCT (e.g., brook trout)
will be discussed in subsequent sections (see Factor E) of this
document.
We believe that intensive monitoring and evaluation of the status
of conservation populations of YCT and their overlapping competitors
over time is necessary and may ultimately indicate whether nonnative
species control actions have been adequately implemented and effective.
If the current trend of nonnative species expansion cannot be halted,
some conservation populations of YCT will likely exhibit a downward
trend over time, and at some point the species may become threatened,
largely as a result of those nonnative species interactions. However,
at this time the best scientific and commercial evidence available to
us does not suggest that the YCT is impacted across its range to the
extent that listing under the ESA as a threatened or endangered species
is warranted.
Factor D. Inadequacy of Existing Regulatory Mechanisms
The ESA requires us to examine the adequacy of existing regulatory
mechanisms with respect to those extant threats that place the species
in danger of becoming either threatened or endangered. In the United
States, YCT are generally managed as a sought-after game fish species
by State fish and wildlife managers in most of the watersheds where
they occur. Each management jurisdiction bases its fishing regulations
on local fish population information, consistent with its overall
regulatory framework and public review process, as well as broader
general management plans and objectives (Caswell and Huffaker 2005;
Hagener 2005; Lewis 2005; Wichers 2005). However, the management
authorities that develop and set the angling regulations typically do
not own or manage the habitat in the watersheds inhabited by
conservation populations of the YCT. Most of that habitat is managed by
Federal land management agencies. Notable major exceptions occur in YNP
and on all or portions of Native American Indian Reservations, where
ownership and management are consolidated. Coordination in
implementation of regulatory mechanisms that are designed to protect
the habitat, with angling regulations allowing public enjoyment of the
species, is vitally important. Numerous examples were submitted to the
USFWS where such coordinated efforts were highlighted (Caswell and
Huffaker 2005; Hagener 2005; Lewis 2005; McAllister 2005; Wichers
2005).
Regulatory Mechanisms Involving Land Management
The status assessment report (May et al. 2003) revealed that
approximately 59 percent (7,125 of the 12,115 km [4,427 of the 7,528
mi]) of habitat presently occupied by all YCT populations (including
both conservation and sport fish populations) lies on lands managed by
Federal agencies. Included within that total are lands with special
management, including those designated as national parks (10 percent of
all occupied habitat on Federal lands), USFS-administered wilderness
areas (14 percent), or other USFS-administered roadless areas (19
percent). Additional lands managed as roadless by the Bureau of Land
Management (BLM) were not quantified, but would add to this total. In
summary, about half of the federally managed land occupied by YCT
occurs in some form of protected habitat.
Numerous State and Federal laws and regulations exist that help to
prevent adverse effects of land management activities on YCT. Federal
laws that protect YCT and their habitats include the Clean Water Act,
Federal Land Management Protection Act, National Forest Management Act,
Wild and Scenic Rivers legislation, Wilderness Act, and the National
Environmental Policy Act (NEPA). The USFS and BLM have adopted the
Inland Native Fish Strategy or similar standards in waters of the Snake
River Basin west of the Continental Divide, that includes standards and
guidelines that help protect the biological integrity of watersheds.
The USFS classifies YCT as a ``sensitive'' species. As a result,
Biological Evaluations include appropriate mitigation for any Forest
project that has the potential to affect YCT.
Greenwald (2005), in comments submitted for the status review
(USFWS 2006), asserts that the National Forest Management Act and other
laws are inadequate and their implementation is insufficient to provide
necessary protections to YCT on USFS lands. However, we have based our
analysis of listing Factor D (Inadequacy of Existing Regulatory
Mechanisms) primarily on the best available scientific and commercial
information regarding the status and trend of the species. We found the
record did not indicate that status and trend of YCT is declining in a
broad pattern, or to such an extent that would indicate a failure of
existing laws and regulatory mechanisms to provide for sufficient
protection of the species habitat on National Forest lands. Greenwald
(2005) cites numerous examples of purportedly inadequate environmental
assessments for timber sales, inadequate resource management plans,
etc., but evidence of ostensibly resultant impacts to the YCT
populations was not provided.
Few other aquatic species listed under the ESA overlap the
distribution of YCT, so YCT currently receive minimal protection from
the ESA's section 7 consultation provisions. Salmon, steelhead, and
bull trout in the Snake River system are all found downstream of
Shoshone Falls (River Mile 614.7), outside the recent historical range
of YCT. Two ESA-listed snail species, the endangered Utah valvata
(Valvata utahensis) documented to occur in the lower Henry's Fork and
in the mainstem Snake River from the mouth of the Henry's Fork
downstream to Grandview (River Mile 487), and the endangered Snake
River physa (Haitia natricina) known to occur in the mainstem Snake
River from Grandview (River Mile 487) as far upstream as Minidoka Dam
(River Mile 674.5), are within the range of YCT. The threatened wetland
plant, Spiranthes diluvialis (Ute ladies'-tresses), occurs in wetlands
along the mainstem Snake River downstream from the Palisades Dam to
American Falls Reservoir and along the Henry's Fork.
Temperature regime also is identified as one of the most important
water quality attributes affecting distribution of some native
salmonids (Rieman and McIntyre 1995; Adams and Bjornn 1997). The U.S.
Environmental
[[Page 8826]]
Protection Agency (EPA) works with USFWS, State environmental quality
agencies, and other entities to develop regional temperature guidance
(USFWS 2002). The goals are to develop EPA regional temperature
criteria guidance that--(1) meet the biological requirements of native
salmonid species for survival and recovery pursuant to the ESA, provide
for the restoration and maintenance of surface water temperature to
support and protect native salmonids pursuant to the Clean Water Act,
and meet the Federal trust responsibilities with treaty tribes for
rebuilding salmon stocks, (2) recognize the natural temperature
potential and limitations of water bodies, and (3) can be effectively
incorporated by States and Tribes in programs concerned with water
quality standards. States and Tribes will use the new criteria guidance
to revise their temperature standards, and if necessary, the EPA and
other agencies will use the new criteria guidance to evaluate State and
Tribal standard revisions.
In Idaho, State regulatory mechanisms that provide some protection
for YCT habitat include the Stream Channel Protection Act, the Lake
Protection Act, and the Forest Practices Act (Caswell and Huffaker
2005). Wyoming has similar regulatory oversight (WDFG 2005). Montana
laws that benefit YCT include the Montana Stream Protection Act, the
Streamside Management Zone Law, the Montana Natural Streambed and Land
Preservation Act, and the Montana Pollutant Discharge Elimination
System (Hagener 2005). The Montana Stream Protection Act requires a
permit be obtained for any project that may affect the natural and
existing shape and form of any stream or its banks or tributaries.
Other State laws, rules, and regulatory mechanisms that help ensure
the conservation of YCT and their habitat in Utah and Nevada are not
discussed, but they are similar to those in the three States (Idaho,
Montana, and Wyoming) where 98 percent of the extant range of the YCT
occurs.
Regulatory Mechanisms That Address Threats From Hybridizing, Nonnative
Fishes
Stocking has been part of Idaho's fisheries management for many
years; indeed, fish stocking is recognized as an integral part of
Idaho's fisheries policy (IDFG 2005). In Idaho, regulatory mechanisms
that will minimize the potential for additional threats to extant YCT
populations from hybridization are now in place (Caswell and Huffaker
2005). The IDFG management efforts to reduce hybridization have
expanded greatly in the past few years. Since 1999, it has been the
policy of IDFG to stock YCT waters with only rainbow trout from eggs
that were heat-shocked to produce triploidy and sterility (Caswell and
Huffaker 2005), thus reducing fish stocking as a source of hybridizing
rainbow trout. The IDFG management direction, as described in its
Fisheries Management Plan (a publicly reviewed, Commission-adopted
document), gives priority in management decisions to wild, native
populations of fish. In addition, the transport of live fish to,
within, and from Idaho is regulated by the IDFG and the Idaho
Department of Agriculture. The IDFG regulates private ponds in the
State and applies the same criteria to private-pond stocking that it
does to the stocking of public waters (i.e., stocking of potentially
hybridizing fishes that may pose a hybridization threat to native
cutthroat trout is prohibited).
Partially in recognition of past problems caused by indiscriminant
fish stocking, Montana has adopted a number of laws and regulatory
mechanisms that address threats posed by the unlawful stocking of
potentially hybridizing, nonnative fishes (Hagener 2005). These include
State statutes, rules, and policies that restrict the capture,
possession, transportation, and stocking of live fish, including fishes
that may hybridize with YCT, as well as rigorous fish-health policies
that restrict the transport or stocking of live fish. The stocking of
private ponds also is closely regulated (Hagener 2005). Furthermore,
although the stocking of rivers and streams with a variety of nonnative
fishes was routine early in the 20th Century, it no longer occurs in
Montana. In 1976, Montana adopted a policy that prohibits the stocking
of hatchery fish in rivers and streams. Consequently, unless done for
government-sponsored conservation purposes, no other trout or nonnative
fish may be stocked in rivers and streams inhabited by YCT in Montana.
Regulatory Mechanisms That Address Threats From Pathogens
The MFWP has established a Fish Health Committee to review all
projects and policies that involve fish health issues and is in the
process of finalizing its Fish Health Policy. This policy establishes
monitoring protocols for State, Federal, and private fish hatcheries;
identifies four classifications of fish pathogens; outlines the
policies and, where appropriate, the permitting processes for
importation or transfer of fish, fish eggs and fish parts; establishes
disinfection procedures of hatchery equipment, hatchery facilities, and
fish eggs; delineates the hatchery quarantine process and procedures;
and establishes policies regarding the importation of aquatic animals.
Montana limits the threat of importation of fish pathogens by
restricting the importation of fish, leeches, and crayfish (Hagener
2005). Importations of fish and fish gametes require an import permit.
Sources of imported fish, fish gametes, and leeches must pass a
rigorous fish health certification process. Nonnative aquatic nuisance
species (ANS) include nonindigenous animal and plant species and
pathogens that can potentially impact native species or their
environments. The ANS may pose a threat to YCT and other Montana native
species through competition, predation, or disruption of the ecology of
their environment (Hagener 2005). In order to proactively respond to
this threat, MFWP formed the Montana Aquatic Nuisance Species Technical
Committee that has completed an Aquatic Nuisance Species Management
Plan that addresses the illegal importation of exotic aquatic animals,
plants, and pathogens. Led by the MFWP ANS Program Coordinator, Montana
coordinates State efforts and funding to prevent accidental
introductions of ANS, limit the spread of established ANS, and
eradicate ANS where feasible.
In Wyoming, similar State regulatory practices are in place. In
Utah and Nevada, the range of YCT is restricted to a few headwater
streams in the lower Snake River portion of the range, specifically in
the Goose and Raft HUCs. For the most part, applicable State laws and
regulations in Utah and Nevada are similar to those detailed in the
other three States (Idaho, Montana, and Wyoming) which comprise
approximately 98 percent of the YCT range.
Greenwald (2005) submitted comments for this status review (USFWS
2006) indicating that the Interstate Yellowstone Cutthroat Trout
Working Group Memorandum of Agreement and a similar Conservation
Agreement for YCT within Montana are voluntary agreements that do not
qualify as regulatory mechanisms. The USFWS agrees with that assessment
and based its finding of the listing status of YCT on the best
available scientific and commercial information regarding the status
and threats to YCT, not on the promised or anticipated results of
conservation actions.
Summary of Factor D
Our status review (USFWS 2006) has not revealed information to
indicate that regulatory mechanisms related to land
[[Page 8827]]
management or fisheries management are not working, or will not work to
protect YCT in the future. As a result of this status review (USFWS
2006) we conclude that the best scientific and commercial information
available to us indicates that any identified inadequacies of existing
regulatory mechanisms have not affected the status of YCT to the extent
that listing under the ESA as a threatened or endangered species is
warranted.
Factor E. Other Natural or Manmade Factors Affecting the Species'
Continued Existence
Fragmentation and Isolation of Small YCT Populations in Headwater Areas
Extant YCT populations are not necessarily small or limited to
headwater streams. Instead, May et al. (2003) indicated that many river
drainages had numerous, interconnected miles of stream habitat occupied
by YCT. Those areas include the nine watersheds previously described as
forming the central core of YCT conservation efforts (Yellowstone
Headwaters, Upper Yellowstone, and Shields in the Yellowstone River
Basin [see Table 1 and Figure 2 in USFWS 2006]; Snake Headwaters, Gros
Ventre, Greys-Hobock, Palisades, Salt, and Teton in the Snake River
basin [see Table 2 and figure 2 in USFWS 2006]).
Although YCT remain widely distributed in two headwater basins, the
effects of human activities combined with natural factors have reduced
the overall distribution and abundance of YCT to an undetermined extent
over the past two centuries (May et al. 2003). Multiple local
populations distributed throughout a watershed provide a mechanism for
spreading risk because the simultaneous loss of all local populations
is unlikely. Migratory corridors allow individuals access to unoccupied
but suitable habitats, foraging areas, and refuges from disturbances.
Where migratory life history forms of salmonid species are not present,
isolated populations cannot be replenished naturally when a disturbance
makes local habitats unsuitable.
Our status review (USFWS 2006) found little direct evidence that
the geographic isolation of YCT populations had resulted in stochastic
extirpations of such populations (due, for example, to natural events
such as floods, landslides, or wildfires). Given the lack of such
evidence it logically follows that such threats are unlikely to occur
to such a degree as to threaten the YCT subspecies or substantial
portions thereof (USFWS 2001). However, the historical record indicates
the distribution of YCT has been substantially reduced over the past
200 years and it is likely that catastrophic natural events contributed
at some level to that loss, even if only affecting isolated
populations. Conservation populations of YCT were determined by May et
al. (2003) to be currently absent from five watersheds where they
historically existed (Pompeys Pillar, Lake Basin, Popo Agie, Lower Wind
River, Lake Walcott), and distribution was extremely limited in single
isolet populations extending through less than 16 km (10 mi) of stream
in five other HUCs (Pryor, Little Bighorn, Upper Tongue, Shoshone, and
North Fork Shoshone). For the most part, these watersheds are in the
downstream margins of the range of YCT, where populations are
noticeably fragmented, and may have been so, historically. We were not
able to determine how much of the currently restricted range of those
populations is due primarily to habitat suitability vs. other threats
such as hybridization with rainbow trout.
Information provided in the YCT status assessment (May et al. 2003)
ranked each of four measures of population viability that could make
YCT vulnerable to catastrophic natural events or adverse human effects
on the aquatic environment--(1) population productivity (i.e.,
demographics), (2) temporal variability, (3) isolation, and (4)
population size. That analysis suggested isolets were at greater risk
of extirpation due to stochastic natural events than were
metapopulations, but the analysis was not rigorously quantitative. We
have also indicated that climatic variables play a role and that YCT
subpopulations on the margins of the range are naturally at greater
risk due to those factors.
Kruse et al. (2001) assessed the possible demographic and genetic
consequences of purposely isolating the populations of YCT in headwater
streams in the Absaroka Mountains, Wyoming. Such isolation may result,
for example, from intentional placement of a movement barrier to
prevent nonnative fishes downstream from invading upstream reaches.
Kruse et al. (2001) speculated that isolated YCT populations are
vulnerable to chance extinction, although they also pointed out that
``there has been little opportunity to observe the real effects of
small population size and isolation on native, extant Yellowstone
cutthroat trout populations.''
The widespread geographic distribution of YCT across the
subspecies' range in portions of five States further mitigates
potential negative effects resulting from local population extinctions
following future catastrophic natural events, as no single event is
likely to impact a significant percent of the overall number of
isolated populations. Moreover, given the widespread efforts for the
conservation of these fish, any such local extirpation that occurs in
habitat where YCT are precluded from naturally recolonizing is likely
to be followed by reintroduction efforts by responsible management
agencies. There is widespread evidence of successful establishment of
reproducing populations of YCT in suitable vacant habitat, often from a
single introduction, as witnessed by the many self-sustaining
populations of YCT found in lakes upstream from geological barriers
that precluded their natural colonization.
Information provided in the YCT status assessment report (May et
al. 2003) indicated that, although 143 (73 percent) of the 195 YCT
conservation populations were isolets that were often restricted to 10
stream miles or less habitat in isolated headwater areas, those isolets
represented only 27 percent of the total stream miles occupied by YCT.
Thus, the small YCT populations in headwater areas are numerous, but
they collectively occupy only about \1/4\ of the total habitat occupied
by YCT conservation populations. Most of the occupied stream miles (73
percent) were habitat for YCT in metapopulations. As a result of this
analysis (USFWS 2006), we conclude that the fragmentation and isolation
of small YCT populations in headwater areas has not resulted in the
subspecies being eliminated from major portions of its historical
range.
Threats to Any of the Three Yellowstone Cutthroat Trout Life-History
Forms
Three life-history forms occur across the range of YCT. We found
that YCT naturally occur in an unquantified but small number of lakes
(probably fewer than 20) across the range. All of the natural YCT
populations dependent on lakes are considered adfluvial (i.e., live in
lakes and migrate into rivers to spawn) and most of them are in areas
where they receive a high level of habitat protection afforded by
national parks or wilderness. However, YCT with the adfluvial life
history constitute a small proportion of the range of YCT and did so
historically.
The State of Wyoming, in comments submitted for this status review
(Wichers 2005), indicated that YNP is an important part of Wyoming and
plays a significant role in YCT conservation but expressed concern that
the importance of YNP to overall YCT
[[Page 8828]]
conservation should not be overstated. Wichers (2005) reported that of
the entire historic stream habitat in Wyoming, 88 percent is outside
YNP and 80 percent of the currently occupied stream miles are outside
YNP. Based on May et al. (2003), YNP accounts for about 4.7 percent of
the historic and 8.5 percent of the presently occupied miles of habitat
across the entire range of YCT. However, we note that Yellowstone Lake
constitutes the majority of existing habitat for the adfluvial life
history form. The significance of this is discussed in greater detail
in the status review (USFWS 2006).
We also found that stream-dwelling resident (i.e., showing little
movement) and fluvial (i.e., migratory within streams and larger
rivers) YCT populations constitute the most common YCT life-history
forms and occur in well over 90 percent of the estimated 12,115 km
(7,528 mi) of occupied habitat distributed among two major stream
drainages (Snake and Yellowstone) and 40 component watersheds. The
distinction between resident and fluvial migratory forms is often
difficult to discern in practice and there is considerable overlap, so
it is not possible to definitively quantify the occupied distribution
of each of these two life history forms. Over the long term,
preservation of all existing life history forms is important to
persistence of YCT. The inherent life form plasticity of the subspecies
and its proven ability to colonize new habitats (i.e., history of fish
culture success) would appear to provide some measure of security for
perpetuation of the adfluvial life history form, which is the most
vulnerable form, into the future.
Fisheries Management
Historic introductions of nonnative species by the Federal
Government, State fish and game departments, and private parties,
across the West have contributed to declines in abundance, local
extirpations, and hybridization of YCT (Gresswell 1995; Kruse et al.
2000; Dunham et al. 2004). In addition, legal and illegal activities
associated with recreational angling are known to be a major vector for
movement and dispersal of nonnative fishes and other organisms (Hagener
2005). The unauthorized or unintentional movement of nonnative
organisms poses a significant but unquantifiable risk associated with
recreational angling.
The States have policies in place to combat these concerns. For
example, the Private Pond Stocking Policy of MFWP restricts what
species of fish may be stocked in private ponds that are in YCT-
occupied drainages of Montana (Hagener 2005). In Wyoming, State Game
and Fish Commission policy precludes the stocking of fish into waters
that are capable of sustaining satisfactory, self-sustaining fisheries
(WGFD 2005). Other States have similar policies (see details in USFWS
2006).
Competition From Introduced Brook Trout
Brook trout, a char species native to eastern North America but
liberally introduced throughout the West, beginning as early as 1900,
can adversely compete with YCT (e.g., Griffith 1988). Brook trout
apparently adapt better to degraded habitats than native trout and
brook trout also tend to occur in streams with higher water
temperatures (Adams and Bjornn 1997). Because elevated water
temperatures and sediments are often indicative of degraded habitat
conditions, native trout may be subject to compounded stresses from
both competitive interactions with brook trout and degraded habitat
(Rieman et al. 2006).
The database of May et al. (2003) did not assess the extent that
brook trout co-occur (i.e., are sympatric) with extant YCT. However, in
future iterations of the database that information will be incorporated
(Brad Shepard, MFWP, pers. comm. 2005). Nonetheless, it is evident from
the longstanding coexistence of brook trout with YCT in some streams
that complete competitive exclusion of YCT by brook trout is not
necessarily inevitable where the two fishes co-occur.
Systematic sampling of the Snake River headwaters in Wyoming
(McAllister 2005) found brook trout were present in approximately 13
percent of the length of all perennial streams occupied by any trout
species or subspecies (but 27 percent of the streams themselves). Brook
trout have displaced cutthroat trout from 14 streams that comprise 1.3
percent of the total trout stream in that watershed. Ten of the 14
streams sampled are tributaries to the Snake River.
In the Teton River, Wyoming, YCT have experienced broad declines
(Koenig 2005) and are seemingly being replaced by brook trout. Benjamin
(2005) reported that only four drainages in the upper Teton River
watershed remain inhabited solely by YCT. Benjamin (2005) hypothesized
that these populations have probably been spared from invasion because
culverts, diversion structures, and dewatered sections prevent fish
from moving from the main Teton River into these tributaries. The nine
largest tributaries in the upper Teton watershed that are occupied by
YCT have been colonized by brook trout.
Although a correlation exists between the spread of brook trout
populations (or other nonnative salmonids) and the decline of YCT in
some watersheds, the causes of YCT population decline often include
multiple currently operating factors (e.g., habitat loss, dewatering,
whirling disease, etc.). As a result, it is difficult to determine
whether brook trout are the cause of YCT decline in such cases or
merely a symptom of broader ecosystem perturbations (Rieman et al.
2006). We conclude that the competition from introduced brook trout is
serious, where it occurs, but it has not affected the status of YCT
conservation populations on a widespread scale. Comprehensive analysis
of the degree of rangewide overlap between YCT and brook trout
distribution is currently not available, but is expected to be a
component of the next iteration of the State status assessment.
Hybridization With Nonnative Fishes
Hybridization with introduced, nonnative fishes, particularly
rainbow trout and their hybrid descendants that have established self-
sustaining populations, is recognized as an appreciable threat to YCT
conservation. The YCT is known to interbreed primarily with rainbow
trout and to a lesser extent with other subspecies of cutthroat trout.
Rainbow trout were first stocked into many regions of the historic
range of YCT more than 100 years ago. May et al. (2003) estimated that
133 of the 195 designated conservation populations (68 percent) would
meet the standard as ``core conservation population,'' essentially
containing nonintrogressed YCT. These 133 potential ``core conservation
populations'' occupy 3,009 km (1,870 mi) of habitat, encompassing about
29 percent of the approximately 10,223 km (6,352 mi) of habitat that
May et al. (2003) considered to be occupied by conservation
populations.
As pointed out by May et al. (2003), the vulnerability to
hybridization of YCT in metapopulations stems from the key
characteristic of the metapopulation itself, i.e., the ability of its
member fish to move (and interbreed) among the various YCT populations
that constitute the metapopulation. It is assumed that potentially
hybridizing fishes are similarly unencumbered in their movements
throughout the geographic area occupied by the metapopulation and,
accordingly, YCT metapopulations can inevitably become completely
introgressed as a hybrid swarm. However, as the following discussion
[[Page 8829]]
shows, the process of hybridization and the results of introgression
are not always predictable.
In Idaho, YCT in many populations are sympatric with potentially
hybridizing rainbow trout but remain nonintrogressed (Meyer et al. 2006
in review). Thus, the occurrence of potentially hybridizing fishes does
not portend their imminent hybridization with YCT. A multitude of
factors, both physical and biological, determine whether or not
introgression may occur, and those factors may not be stable over time.
For example, in some circumstances drought cycles may serve to isolate
spawning populations of YCT, possibly limiting access to potentially
introgressing fish in YCT habitat. However, in other cases drought
could have the opposite effect by limiting YCT access to traditional
spawning streams where spatial or temporal isolation historically
occurred; thereby forcing fish to spawn together in greater proximity
and contributing to increased introgression.
In the Yellowstone River in Montana, De Rito (2004) assessed
whether spatial or temporal reproductive isolation, or both, occurs
between YCT and nonnative rainbow trout. Time and place of spawning
were determined by radiotelemetry of 164 trout (98 cutthroat, 37
rainbow, and 29 cutthroat x rainbow hybrids) over 3 spawning seasons,
from 2001 to 2003. Spawning area and spawning-reach overlap were high
among all taxa. In contrast, mean migration and spawning dates of
rainbow trout and hybrids were 5 to 9 weeks earlier than for cutthroat
trout. Rainbow trout and hybrids began migrating and spawning in April
and May when Yellowstone River discharges were lower and water
temperatures were colder. In contrast, cutthroat trout migration and
spawning occurred in June and July, when discharges and temperatures
were higher. De Rito (2004) concluded that difference in time of
spawning is likely the predominant mechanism eliciting reproductive
isolation. He further concluded that conservation actions that focused
on protecting and enhancing later spawning cutthroat trout in
tributaries may enhance temporal reproductive isolation from rainbow
trout and their hybrids.
There are scattered populations of WCT or other nonnative cutthroat
trout subspecies found within the range of YCT, as a result of past
introductions. However, due to the widespread popularity of fish
culture activities using YCT, the opposite pattern (e.g., YCT stocked
in the native range of WCT) is a much more common occurrence. The
present hybridization risk to YCT is almost entirely from rainbow
trout.
In most cases today, it is not technologically possible to
eliminate the self-sustaining populations of potentially hybridizing,
nonnative fishes from entire drainages or even individual streams.
Consequently, perceived threats to extant YCT posed by nonnative fishes
in streams are sometimes met by installing barriers to the upstream
movement of the nonnative fishes into stream reaches occupied by core
populations of nonintrogressed YCT. In a few cases, usually involving
small streams that provide the greatest opportunity for success, fish
toxins may be used to completely remove all fishes upstream from such
barriers, after which YCT may be stocked (Caswell and Huffaker 2005;
Hagener 2005; Lewis 2005; WGFD 2005). Because of technological,
budgetary, and other limitations, actions to eliminate or isolate
sources of introgression are now being taken for only a small
proportion of YCT populations across the subspecies' range.
Self-sustaining populations of nonnative rainbow trout pose the
greatest hybridization threat to YCT and few of those populations can
be eliminated or appreciably reduced. A key concern becomes the extent
that introgressive hybridization may eventually pervade existing
nonintrogressed or suspected nonintrogressed YCT populations,
particularly those that inhabit headwater streams in high-elevation
areas.
Meyer et al. (2003) found that YCT hybridization with rainbow trout
in the Upper Snake River basin is far from ubiquitous, with only 19
percent of the sites containing YCT also containing rainbow trout or
hybrids (see additional discussion in USFWS 2006). The finding that
hybridization is not widespread across the Upper Snake River basin
comports with range-wide findings of May et al. (2003) for YCT.
In addition, many extant YCT populations occur upstream from
natural barriers that prevent the existing upstream movement of
nonnative fishes, including those that may potentially hybridize with
YCT. We examined the database of May et al. (2003) to determine the
extent that nonintrogressed or suspected nonintrogressed YCT
populations occur upstream from such ``complete'' barriers. Results
indicated that a little over 3,219 km (2,000 mi) of stream habitat
occupied by YCT conservation populations, including about 748 km (465
mi) inhabited by YCT in the 143 isolated populations and about 2,585 km
(1,606 mi) inhabited by YCT in metapopulations are upstream from
barriers. Of these, a high proportion is populated by nonintrogressed
YCT with no hybridizing rainbow trout or other species in proximity.
The observation that numerous nonintrogressed YCT populations
persist today despite the longstanding sympatric occurrence (i.e., more
than 100 years) of potentially hybridizing fishes, or their presence in
downstream reaches where the absence of barriers to the upstream
movement of those fish occurs, corroborates the physical evidence that
not all nonintrogressed YCT populations have been and are equally
vulnerable to introgression. The threat of hybridization with nonnative
rainbow trout and the potential for introgression to occur to such an
extent as to compromise the integrity of conservation populations of
YCT is a complex and still evolving dynamic process. While we do not
discount this threat and believe it may present one of the single
biggest challenges to the continued conservation of YCT, we are
encouraged that the most recent scientific studies (e.g., Meyer et al.
2003, De Rito 2004, Novak et al. 2005, Meyer et al. 2006 in review)
indicate that substantial genetic isolation of YCT may persist, even in
sympatry with populations of rainbow trout. These data would appear to
indicate that the level of genetic isolation has not been increasing.
New Zealand Mud Snails
New Zealand mud snails (NZMS), an invasive nonnative mollusk, can
coat benthic/food producing areas, has not been found in any areas
currently occupied by wild populations of YCT in Wyoming (WGFD 2005).
In 2002, NZMS were discovered in the Big Horn River (Upper Big Horn
HUC) near Thermopolis, Wyoming. High densities of NZMS exist in Polecat
Creek, a tributary to the Snake River near the YNP boundary. Polecat
Creek is a geothermally heated stream, which likely contributes to the
high densities of NZMS observed. NZMS can be found in the Snake River
above Jackson Lake, but in lower densities than in Polecat Creek. No
additional information on the range or spread of NZMS within the
conservation habitat of YCT was reviewed. While it is likely this
organism is increasingly becoming more widespread and will continue to
spread, to date there is no evidence that implicates NZMS in the
collapse of any conservation populations of YCT.
[[Page 8830]]
Summary of Factor E
As a result of our status review (see USFWS 2006), we conclude the
best scientific and commercial information available indicates that
risk associated with fragmentation and isolation of small YCT
conservation populations, including stochastic risk from catastrophic
natural events, has not affected the status of YCT to the extent that
listing under the ESA as a threatened or endangered species is
warranted.
The available data also do not suggest the future loss of any of
the three life-history forms represented by YCT, although the adfluvial
form is clearly the most vulnerable. We conclude the best scientific
and commercial information available to us indicates that threats to
any of the three YCT life-history forms have not affected the status of
the YCT to such an extent that listing under the ESA as a threatened or
endangered species is warranted.
In our 90-day finding (66 FR 11244) we concluded that ongoing
fisheries management programs were not a sufficient threat to the
status of YCT to cause us to consider listing. Likewise, the presence
of introduced, nonnative fishes such as brook trout did not necessarily
portend the imminent decline or elimination of YCT. This status review
(see USFWS 2006) supports that conclusion.
As a result of this analysis, we also conclude the best scientific
and commercial information available to us indicates that introgressive
hybridization with rainbow trout or other cutthroat subspecies has not
affected the status of YCT to the extent that listing under the ESA as
a threatened or endangered species is warranted. However, we will
continue to evaluate new information that may be made available
regarding these and other threats, and we urge the public to submit to
us any new information that becomes available concerning the status of
or threats to YCT. That is particularly true of new threats such as the
recent spread of invasive New Zealand mud snails.
Petition Finding
In the context of the ESA, the term ``threatened species'' means
any species (or subspecies or, for vertebrates, DPS) 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 ESA does not indicate
threshold levels of historic population size at which, as the
population of a species declines, listing as either ``threatened'' or
``endangered'' becomes warranted. Instead, the principal considerations
in the determination of whether or not a species warrants listing as a
threatened or an endangered species under the ESA are the threats that
now confront the species and the probability that the species will
persist in ``the foreseeable future.'' The ESA does not define the term
``foreseeable future.'' However, the YCT Interstate Workgroup that
produced the YCT status assessment report (May et al. 2003) which
formed much of the scientific basis for our status review (USFWS 2006)
considered the ``foreseeable future'' to be 20 to 30 years (which
equates to approximately 4 to 10 YCT generations, depending on the
productivity of the environment). That is a measure that the USFWS
supports as both reasonable and appropriate for our status review
(USFWS 2006) because it is long enough to take into account multi-
generational dynamics of life-history and ecological adaptation, yet
short enough to incorporate social and political change that affects
species management.
In our status review (USFWS 2006), we provided evidence that
indicates a decline in YCT occurred over the past 200 years, but much
of that loss is believed to have occurred in the late 19th and early
20th century. Recent trends appear to be stable or upward, with a few
notable exceptions (i.e., Yellowstone Lake, Teton River). Although YCT
remain widely distributed in two headwater basins, the overall
abundance of YCT have declined to an undetermined extent over the past
two centuries (May et al. 2003). We attribute the distributional
decline of YCT in large measure to competition, hybridization, and
predation caused by one or more nonnative fish species. These impacts
have been observed since the initial introductions of brown trout,
rainbow trout, and brook trout began in the late 1800s. These
introduced salmonid species have subsequently expanded to colonize new
habitat and form many naturally reproducing populations occupying the
range of YCT. More recently, lake trout introduction has been a major
factor in causing decline of the adfluvial YCT population of
Yellowstone Lake.
Coinciding with, and largely inseparable in its effect on YCT from
the impacts of nonnative species introduction, has been a gradual and
in some instances substantial decline in overall quality of in-stream
fish habitat and riparian status. This has occurred largely as a result
of human-caused land and water management practices. Increased sediment
and reduced or altered streamflow patterns are considered the primary
causes of reduced habitat quality for native salmonid populations
throughout the west. These impacts have probably been exacerbated by
natural or man-caused climate changes that have led to generally warmer
and drier conditions. Such conditions generally do not favor cutthroat
trout, especially in watersheds occupying the margins of suitable
habitat within their historical range.
Our analysis for this review (USFWS 2006) found there is little
evidence of major changes in overall distribution or abundance of YCT
over approximately the past decade. There are indications that
increased focus is being placed by management agencies on the
protection and restoration of conservation populations of YCT in many
watersheds. Corresponding emphasis is occurring on habitat restoration
activities and fisheries management actions such as restrictive angling
regulation changes that are designed to benefit YCT. For many of these
actions, it is too early to judge their success. Some of these actions
appear to have resulted in improved population levels in some areas.
Examples are found in the Snake River Headwaters of Wyoming (Novak et
al. 2005), portions of Idaho (Meyer et al. 2003; Meyer et al. 2006 in
review), the Shields River watershed in Montana (Hagener 2005), and
other locations. At the same time, this success is countered by
evidence of recent dramatic declines in a formerly robust population of
YCT within the relatively secure habitat of Yellowstone Lake in YNP
(Koel et al. 2005), documented declines and recruitment failure in the
Teton River watershed in Wyoming and Idaho (Benjamin 2005; Koenig
2005), and concerns over the status and threats due to selenium
toxicity in the Blackfoot River and possibly other watersheds in Idaho
(Lemly 1999; Christensen 2005). In balance, the monitoring record is
insufficient to document either an overall upward or downward trend in
the status of YCT populations across the subspecies' historic range
over the recent past.
It is important that the status and distribution of YCT continue to
be monitored. The USFWS finds that the management agencies are
contributing substantial resources in that regard, and we believe the
planned upgrade of the YCT status assessment to be initiated by the
Yellowstone Cutthroat Trout Interstate Workgroup in 2006 (WGFD 2005;
Brad Shepard, MFWP, pers. comm. 2005) will become an important
[[Page 8831]]
document for establishing an accurate current baseline to be used to
evaluate future population status changes.
Conclusions
On December 17, 2004, Judge Figa (U.S. District Court of Colorado)
ordered the USFWS to complete a 12-month status review for YCT. As a
result, we have done so and present our conclusions in this notice, and
in more detail in the accompanying status review (USFWS 2006). The
information we have summarized includes substantial amounts of new
information not analyzed or reported in our previous 90-day finding (66
FR 11244), particularly that obtained from the status report of May et
al. (2003). That information indicates at least 195 extant YCT
conservation populations, qualifying as YCT under the standards we have
adopted, collectively occupy 10,220 km (6,352 mi) of stream and lake
habitat in Idaho, Montana, Wyoming, Utah, and Nevada. Those 195 YCT
populations are distributed among 35 component watersheds in the Snake
and Yellowstone River basins, within the international boundaries of
the United States.
Of those 195 conservation populations, about 133 were considered
likely to qualify as potential ``core conservation populations''
comprised of nonintrogressed YCT (99 percent genetic purity standard;
see Discussion of Hybrid YCT in Listing Determinations at the beginning
of the status review [USFWS 2006]). If, after further genetic testing
the existence of approximately 133 core conservation populations is
verified, then those populations would include about 3,009 km (1,870
mi) of habitat encompassing about 29 percent of the existing range of
conservation populations of YCT.
Although the distribution of YCT has been reduced from historic
levels and existing populations face threats in several areas of the
historic range, we find that the magnitude and imminence of those
threats do not compromise the continued existence of the subspecies
within the foreseeable future (which we define as 20-30 years). Many
former threats to YCT, such as those posed by excessive harvest by
anglers or the ongoing stocking of nonnative fishes, are no longer
factors that threaten the continued existence of YCT. That is not to
downplay the active legacy of past fish stocking activities, but
current programs have been revised to avoid further impacts. The
effects of other extant threats, especially those to habitat, may be
effectively countered, at least in part, by the ongoing management
actions of State and Federal agencies. These actions occur in
conjunction with application of existing regulatory mechanisms. It is
largely too soon to judge the overall long-term effectiveness of those
actions, though some positive signs are present. At the least, we
conclude that active loss of habitat has been minimized.
Nonetheless, hybridization with nonnative rainbow trout or their
hybrid progeny and descendants, both of which have established self-
sustaining populations in many areas in the range of YCT, remains an
active threat in the form of introgression to YCT conservation
populations. The eventual extent that hybridization occurs in YCT
habitat may be stream-specific and impossible to predict. Nonetheless,
the criteria that we adopted for inclusion of individual fish or
populations as YCT, following the lead of past actions (see WCT finding
in USFWS 2003; 66 FR 46989) and consistent with the genetic standards
adopted by the State fishery managers (Utah Division of Wildlife
Resources 2000), allow for the limited presence in YCT conservation
populations of genetic material from other fish species. We view this
as consistent with the intent and purpose of the ESA.
The YCT remain widely distributed and there are numerous robust YCT
populations and metapopulations throughout the subspecies' historic
range. Moreover, numerous nonintrogressed YCT populations are
distributed in secure habitats throughout the subspecies' historic
range. In addition, despite the frequent occurrence of introgressive
hybridization, we find that some YCT populations that are sympatric
with rainbow trout are nonintrogressed or nearly so, and thus retain
substantial portions of their genetic ancestry, apparently due to
temporal, behavioral, or spatial reproductive isolation. We consider
slightly introgressed YCT populations, with low amounts of genetic
introgression detectable only by molecular genetic methods, to be a
potentially important and valued component of the overall YCT (i.e.,
``conservation populations'').
Finally, the numerous ongoing YCT conservation efforts clearly
demonstrate the broad interest in protecting YCT held by State,
Federal, Tribal, local, and nongovernmental organizations and other
entities. However, those ongoing conservation efforts, while important,
are not pivotal to our decision whether or not to propose to list the
YCT as either a threatened or an endangered species under the ESA. That
decision is based mainly on the present-day status and trend of YCT,
the mitigation of many of the existing threats, and the occurrence of
the numerous extant laws and regulations that work to prevent the
adverse effects of land-management and other activities on YCT,
particularly on those lands administered by Federal agencies.
On the basis of the best available scientific and commercial
information, which has been broadly discussed in this notice and
detailed in the documents contained in the Administrative Record for
this decision, we conclude that the YCT is not endangered (threatened
with extinction within the foreseeable future), nor is it threatened
with becoming endangered within the foreseeable future. Therefore,
listing of the YCT as a threatened or an endangered species under the
ESA is not warranted at this time.
References Cited
A complete list of all references cited herein is available upon
request from the Field Supervisor at the Montana Ecological Services
Office (see ADDRESSES).
Author
The primary author of this document is the Montana Ecological
Services Office (see ADDRESSES).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: February 14, 2006.
H. Dale Hall,
Director, Fish and Wildlife Service.
[FR Doc. 06-1539 Filed 2-17-06; 8:45 am]
BILLING CODE 4310-55-P