[Federal Register Volume 73, Number 94 (Wednesday, May 14, 2008)]
[Proposed Rules]
[Pages 27900-27926]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-10182]



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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Status Review for Rio 
Grande Cutthroat Trout; Proposed Rule

Federal Register / Vol. 73, No. 94 / Wednesday, May 14, 2008 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R2-ES-2008-0056; 1111 FY07 MO-B2]


Endangered and Threatened Wildlife and Plants; Status Review for 
Rio Grande Cutthroat Trout

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of candidate status review.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce the 
results of the status review for the Rio Grande cutthroat trout 
(Oncorhynchus clarki virginalis) under the Endangered Species Act of 
1973 (Act), as amended. After a thorough review of all available 
scientific and commercial information, we find that listing the Rio 
Grande cutthroat trout is warranted but precluded by higher priority 
actions. Upon publication of this status review, we will add the Rio 
Grande cutthroat trout to our list of candidate species with a listing 
priority number of 9, because the threats affecting it have a moderate 
magnitude and are imminent. We will develop a proposed rule to list the 
subspecies as our priorities allow. 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 announced in this document was made on May 14, 2008.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov. Supporting documentation we used in preparing this 
finding is available for public inspection, by appointment, during 
normal business hours at the U.S. Fish and Wildlife Service, New Mexico 
Ecological Services Field Office, 2105 Osuna Road, NE., Albuquerque, 
New Mexico 87113; telephone (505) 346-2525; facsimile (505) 248-6788. 
Please submit any new information, materials, comments, or questions 
concerning this finding to the above address or via electronic mail (e-
mail) at <a href="/cdn-cgi/l/email-protection#7301411504162c121f331504005d141c05"><span class="__cf_email__" data-cfemail="cbb9f9adbcae94aaa78badbcb8e5aca4bd">[email protected]</span></a>.

FOR FURTHER INFORMATION CONTACT: Wally ``J'' Murphy, Field Supervisor, 
U.S. Fish and Wildlife Service, 2105 Osuna Road, NE., Albuquerque, New 
Mexico 87113. (505) 346-2525 ext 106. If you use a telecommunications 
device for the deaf (TDD), call the Federal Information Relay Service 
(FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires 
that, for any petition containing 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 that 
immediate proposal of a regulation implementing the petitioned action 
is precluded by other pending proposals to determine whether species 
are threatened or endangered, and expeditious progress is being made to 
add or remove qualified species from the Lists of Endangered and 
Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires 
that we treat a petition for which the requested action is found to be 
warranted but precluded as though resubmitted on the date of such 
finding, that is, requiring a subsequent finding to be made within 12 
months. We must publish these 12-month findings in the Federal 
Register.

Previous Federal Actions

    On February 25, 1998, we received a petition from Kieran Suckling, 
of the Southwest Center for Biological Diversity requesting that the 
Service add the Rio Grande cutthroat trout (Oncorhynchus clarki 
virginalis) to the list of threatened and endangered species. The 
petition addressed the range-wide distribution of the Rio Grande 
cutthroat trout that includes populations in Colorado and New Mexico. 
We subsequently published a notice of a 90-day finding in the Federal 
Register (63 FR 49062) on September 14, 1998. In the 90-day finding we 
concluded that the petition did not present substantial information 
indicating that listing of the Rio Grande cutthroat trout may be 
warranted.
    On June 9, 1999, a complaint was filed by the Southwest Center for 
Biological Diversity alleging that the September 14, 1998, 90-day 
petition finding violated the Administrative Procedure Act. While the 
litigation was pending, we received information (particularly related 
to the presence of whirling disease in hatchery fish in the wild) that 
led us to believe that further review of the status of the subspecies 
was warranted. On November 8, 2001, a settlement agreement executed by 
both parties (the Service and the Southwest Center for Biological 
Diversity) was filed with the court. The settlement stipulated that the 
Service would initiate a status review for the Rio Grande cutthroat 
trout, make a determination on or before June 4, 2002, and shortly 
thereafter, publish our determination in the Federal Register. On June 
11, 2002, we published our determination that listing of Rio Grande 
cutthroat trout was not warranted (67 FR 39936).
    Subsequently, on February 25, 2003, the Center for Biological 
Diversity, along with several other organizations, sued the Service for 
failing to list Rio Grande cutthroat trout. On June 7, 2005, the New 
Mexico Federal District Court (Court) ruled that our finding was not 
arbitrary and capricious, but also required that we explain in more 
detail our analysis of ``significant portion of the range''. The Court 
ordered the Service to provide a supplemental briefing discussing in 
more detail our analysis of significant portion of the range. We 
submitted this briefing on July 20, 2005. On December 19, 2005, the 
Court ruled in favor of the Service and upheld our interpretation of 
significant portion of the range and determined that our evaluation of 
Rio Grande cutthroat trout's status under the listing criteria was not 
arbitrary and capricious. Plaintiffs appealed this decision.
    The appeal was pending with the Tenth Circuit Court of Appeals, 
when other courts issued opinions for other species that required the 
Service to reexamine our position on significant portion of the range. 
On March 16, 2007, a formal opinion was issued by the Solicitor of the 
Department of the Interior, ``The Meaning of In Danger of Extinction 
Throughout All or a Significant Portion of Its Range'' (U.S. DOI 2007). 
Because of this new formal opinion and because of our knowledge of 
changes in status of some populations that we had defined as ``secure'' 
in our 2002 review, in consultation with the court and the plaintiffs, 
the Service agreed to initiate a new status review. We subsequently 
published a notice seeking new information concerning the status of Rio 
Grande cutthroat trout on May 22, 2007 (72 FR 28664).
    In response to our 2007 requests for information regarding Rio 
Grande cutthroat trout (72 FR 28664, 72 FR 46030 (August 16, 2007)), we 
received comments and information from Colorado Division of Wildlife 
(CDOW), New Mexico Department of Game and Fish (NMDGF), U.S. Bureau of 
Land Management (BLM), U.S. Forest Service (USFS), private citizens and 
organizations, and the Rio Grande Cutthroat Trout Conservation Team. 
The Rio Grande Cutthroat Trout

[[Page 27901]]

Conservation Team is composed of biologists from CDOW, NMDGF, BLM, 
USFS, National Park Service, the Jicarilla Apache Nation and the 
Service. The Rio Grande Cutthroat Trout Conservation Team recently 
completed a range-wide status report (Alves et al. 2007) concerning the 
Rio Grande cutthroat trout. The status report and the comprehensive 
database (referred to as ``2007 database'' in this finding) that is the 
basis for the report, along with other supplemental submissions from 
the agencies listed above, provide the best scientific and commercial 
information available on Rio Grande cutthroat trout. The report 
summarizes information provided by 15 fisheries professionals from 
Colorado and New Mexico having specific knowledge of Rio Grande 
cutthroat trout (Alves et al. 2007, p. 58). In making this finding, we 
considered all scientific and commercial information that we received 
or acquired since our previous status review. We relied primarily on 
published and peer-reviewed documentation for our conclusions.

Biology and Distribution

    The Rio Grande cutthroat trout, one of 14 subspecies of cutthroat 
trout, is native to the Rio Grande, Pecos, and the Canadian river 
basins in New Mexico and Colorado (Behnke 2002, p. 219). Rio Grande 
cutthroat trout has the distinction of being the first North American 
trout recorded by Europeans (Behnke 2002, p. 139). In 1541, Francisco 
de Coronado's expedition discovered Rio Grande cutthroat trout in the 
upper Pecos River (Behnke 2002, p. 139). The first specimens that were 
collected for scientific purposes came from Ute Creek in Costilla 
County, Colorado, in 1853. Rio Grande cutthroat trout was originally 
described in 1856 (Behnke 2002, p. 210). Cutthroat trout subspecies are 
distinguished by the red to orange slashes in the throat folds beneath 
the lower jaw.
    The historical distribution of Rio Grande cutthroat trout is not 
known with certainty. In general, it is assumed that Rio Grande 
cutthroat trout occupied all streams capable of supporting trout in the 
Rio Grande, Pecos, and Canadian basins (Alves et al. 2007, p. 9). The 
Pecos River is a tributary of the Rio Grande, so a historic connection 
between the two basins likely existed. Although no early museum 
specimens document its occurrence in the headwaters of the Canadian 
River, it is almost certainly native there as well (Behnke 2002, p. 
208). The Canadian River, tributary to the Mississippi River, has no 
connection with the Rio Grande. It is possible that through headwater 
capture (a tributary from one watershed joins with a tributary from 
another) there may have been natural migration of fish between the 
Pecos and Canadian headwater streams. There is evidence that Rio Grande 
cutthroat trout may have occurred in Texas (Garrett and Matlock 1991, 
p. 405; Behnke 1967, pp. 5, 6) and Mexico (Behnke 1967, p. 4). 
Currently, the southernmost distribution of Rio Grande cutthroat trout 
occurs in Animas Creek, Sierra County, New Mexico, and Indian Creek on 
the Mescalero Apache Indian Reservation in Otero County, New Mexico. 
Distribution in the southern portion of the range is currently limited 
and no conservation populations (see discussion of conservation 
populations below) exist south of Santa Fe, New Mexico.
    In the range-wide status report, historically occupied habitat was 
based on habitat believed to be inhabited by Rio Grande cutthroat trout 
when early European explorers entered the Southern Rocky Mountain 
Region of Colorado and New Mexico (circa 1800) (Alves et al. 2007, p. 
9). In general, streams currently capable of supporting trout 
(elevations of 1,829 meters (m) (6,000 feet (ft)) and above; 1,671 m 
(5,500 ft) and above on north-facing slopes) were assumed to have been 
historically occupied if they were not above a barrier to fish movement 
(e.g., an impassable waterfall). Streams which cannot currently support 
trout were assumed not to have been historically occupied unless they 
were known to have been degraded by such things as water withdrawals, 
channel alterations, human-caused barriers, or chemical contamination. 
Based on these criteria, 10,622 kilometers (km) (6,660 miles (mi)) of 
stream habitat were identified as having the potential of being 
historically occupied by Rio Grande cutthroat trout (Alves et al. 2007, 
p. 9). The estimated amount of historical range in each State is about 
5,196 km (3,229 mi) in Colorado (48 percent), and 5,521 km (3,431 mi) 
(52 percent) in New Mexico (Alves et al. 2007, p. 9).
    To facilitate management and conservation efforts, the Rio Grande 
cutthroat trout range is divided into Geographic Management Units 
(GMUs) based on watersheds (Alves et al. 2007, p. 2). The GMUs are, 
from north to south, Rio Grande headwaters, Lower Rio Grande, Canadian, 
Pecos, and Caballo. Historical occupancy by GMU is 5,277 km (3,279 mi) 
(49 percent) in Rio Grande Headwaters, 3,396 km (2,110 mi) (32 percent) 
in Lower Rio Grande, 1,027 km (638 mi) (10 percent) in the Canadian, 
1,003 km (623 mi) (9 percent) in Pecos, and 16 km (10 mi) (0.2 percent) 
in Caballo (Alves et al. 2007, p. 9).
    In our prior status review (67 FR 39936; June 11, 2002), we focused 
our analysis primarily on ``core'' populations, which we defined using 
conservative criteria for genetic integrity, population stability, and 
security from invasion by nonnative salmonids (trout and salmon). The 
genetic criterion for these core populations was that the populations 
have less than one percent representation of genetic markers from 
another subspecies of cutthroat trout or from rainbow trout 
(Oncorhynchus mykiss), as determined by genetic testing. Rio Grande 
cutthroat trout are able to interbreed, or hybridize, with other 
subspecies of cutthroat trout and rainbow trout. This hybridization may 
result in genes of one species or subspecies being incorporated into 
the other species or subspecies. The incorporation of genes from one 
species into another is referred to by the technical term 
``introgression'' (Mayr 1970) and a species that has received such 
genes is referred to as ``introgressed.'' To simplify discussion in 
this review, we will also use these terms when describing when genetic 
markers of another subspecies are found in Rio Grande cutthroat trout, 
although we recognize that these terms, as strictly defined, refer to 
species.
    Our previous status review concluded that the core populations, as 
then defined by conservative criteria, were sufficiently abundant, 
distributed, and secure to conclude that listing of the Rio Grande 
cutthroat trout was not warranted. As described later in this review, 
the status of several of the original core populations has subsequently 
declined and we believe those populations alone are not sufficient to 
conserve the Rio Grande cutthroat trout.
    For the current review, the genetic criterion for core populations 
is that they be less than one percent introgressed, which is the same 
genetic criterion for core populations followed in the previous review. 
Although population stability and security from invasion are not used 
to define core populations, as they were in the previous review, those 
factors are still addressed as attributes affecting the status of core 
and other populations. Core populations in the current review 
correspond to the core populations described in the multi-state 
position paper for cutthroat management (Utah Division of Wildlife 
Resources (UDWR) 2000, pp. 3, 4). In addition to these core 
populations, we focused our review on ``conservation populations'' as 
defined

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by the position paper (UDWR 2000): populations less than 10 percent 
introgressed, as measured by genetic markers, and that retain the 
ecological, behavioral, and phenotypic characteristics of Rio Grande 
cutthroat trout. In addition, we have included as conservation 
populations those populations which have not been genetically tested, 
but that retain the ecological, behavioral, and phenotypic 
characteristics of Rio Grande cutthroat trout and are not suspected to 
be introgressed or co-occurring with hybridizing species.
    The above criteria for core and conservation populations have been 
applied in Service status reviews of other subspecies of cutthroat 
trout published since 2002 (71 FR 8818; 72 FR 32589). The status review 
(68 FR 46989; August 7, 2003) for the westslope cutthroat trout 
(Oncorhynchus clarki lewisi) included populations with up to 20 percent 
introgression, based on several studies of genetic markers and 
morphological traits of introgressed populations that indicate that 
populations with up to 20 percent of their nuclear genes derived from 
rainbow trout were morphologically indistinguishable from 
nonintrogressed westslope cutthroat trout populations. Comparable 
studies, where genetic and morphological characters in the same 
population are studied, have not been performed on Rio Grande cutthroat 
trout; therefore, we have no justification for departing from the 
general criterion of less than 10 percent introgression proposed in the 
position paper on cutthroat trout genetics (UDWR 2000).
    In the remainder of this review, we collectively refer to both core 
and conservation populations, as defined above, as conservation 
populations.
    Inclusion of conservation populations with up to 10 percent 
introgression in the present review does not mean we are any less 
concerned about the effects of introgression on Rio Grande cutthroat 
trout. Our evaluation of introgression as a threat to the Rio Grande 
cutthroat trout will be described along with other applicable threats 
later in this review.
    Alves et al. (2007, p. 26) report that 120 conservation populations 
of Rio Grande cutthroat trout currently occupy about 1110 km (690 mi) 
of habitat, or 10.4 percent of the historical range of the subspecies. 
The 120 conservation populations include 12 populations that have not 
been tested for introgression and are suspected to be hybridized and 
one population that to date has tested as nonintrogressed but in which 
rainbow trout, a hybridizing species, co-occurs (Alves et al. 2007, p. 
34; 2007 data base). An additional two streams (Placer Creek and 
Comanche Creek) included in the 120 are undergoing restoration and are 
currently unoccupied by Rio Grande cutthroat trout. Although we fully 
expect these two streams will become conservation populations within 
the next five years, they are not occupied by viable populations 
currently. Although we included in our analysis untested populations 
that are suspected to be nonintrogressed as conservation populations, 
we do not feel it is appropriate to include untested populations that 
are suspected to be introgressed or that co-occur with hybridizing 
species. Alves et al. (2007) provided all summary statistics (e.g., 
percent populations with nonnative trout, percent historical habitat 
occupied, number of populations in each state) for 120 conservation 
populations. Although the inclusion of these populations in Alves et 
al. (2007) inflates the number of conservation populations and miles of 
stream occupied by Rio Grande cutthroat trout, their inclusion does not 
make a material difference in the outcome of our finding. Therefore, we 
have decided to present all summary statistics as presented in Alves et 
al. (2007) rather than recalculate the summary statistics to reflect 
the 105 populations we would classify as conservation populations.
    Rio Grande cutthroat trout conservation populations currently 
occupy about 473 km (294 mi) in Colorado (9.1 percent of Colorado 
historical habitat) and 637 km (396 mi) in New Mexico (11.6 percent of 
historical habitat) (Alves et al. 2007, p. 26). The Lower Rio Grande 
GMU contains the largest amount of occupied habitat (489 km (304.1 
mi)), followed by the Rio Grande Headwaters GMU (452 km (281.4 mi)), 
Canadian GMU (109 km (67.5 mi)), and Pecos GMU (60 km (37.3 mi)) (Alves 
et al. 2007, p. 26). The Caballo GMU contains a hybridized population 
of cutthroat trout that was not included as a conservation population. 
Rio Grande cutthroat trout occupy habitat in 14 of 19 watersheds that 
supported historical habitat. They are believed to be extirpated from 
the following watersheds: Arroyo Del Macho, Caballo, Upper Canadian, 
Rio Hondo, and Rio Penasco (Alves et al. 2007, p. 11). If Rio Grande 
cutthroat trout once occurred in Texas and Mexico, there is no evidence 
that they occur there now.

Life History

    As is true of other subspecies of cutthroat trout, Rio Grande 
cutthroat trout is found in clear cold streams. Unlike some subspecies 
of cutthroat trout, such as the Bonneville (Oncorhynchus clarki utah) 
and Yellowstone (Oncorhynchus clarki bouvieri), Rio Grande cutthroat 
trout did not originally inhabit large lake systems. However, they have 
been introduced into coldwater lakes and reservoirs. They spawn as high 
water flows from snowmelt recede. In New Mexico, this typically occurs 
from the middle of May to the middle of June (NMDGF 2002, p. 17). 
Spawning is believed to be tied to day length, water temperature, and 
runoff (Sublette et al. 1990, p. 54; Behnke 2002, p. 141).
    It is unknown if Rio Grande cutthroat trout spawn every year or if 
some portion of the population spawns every other year as has been 
recorded for westslope cutthroat trout (McIntyre and Rieman 1995, p. 
1). Likewise, while it is assumed that females mature at age 3, they 
may not spawn until age 4 or 5 as seen in westslope cutthroat trout 
(McIntyre and Rieman 1995, p. 3). Sex ratio also is unknown with 
certainty, but based on field data, a ratio skewed towards more females 
might be expected (Pritchard and Cowley 2006, p. 27). Although 
Yellowstone (Gresswell 1995, p. 36), Bonneville (Shrank and Rahel 2004, 
p. 1532), and westslope (Bjornn and Mallet 1964, p. 73; McIntyre and 
Rieman 1995, p. 3) cutthroat trout subspecies are known to have a 
migratory life history phase, it is not known if Rio Grande cutthroat 
trout once had a migratory form when there was connectivity among 
watersheds.
    Most cutthroat trout are opportunistic feeders, eating both aquatic 
invertebrates and terrestrial insects that fall into the water 
(Sublette et al. 1990, p. 54). Rio Grande cutthroat trout evolved with 
Rio Grande chub (Gila pandora), longnose dace (Rhinichthys cataractae) 
(all basins); Rio Grande sucker (Catastomus plebius) (Rio Grande 
Basin); white sucker (C. commersoni) and creek chub (Semotilus 
atromaculatus) (Pecos and Canadian Basins); and the southern redbelly 
dace (Phoxinus erythrogaster) (Canadian River Basin) (Rinne 1995, p. 
24). Many of these fish have either been extirpated from streams with 
Rio Grande cutthroat trout or are greatly reduced in number (Sublette 
et al. 1990, p. 162; Calamusso and Rinne 1999, pp. 233-236). It is not 
known if they once were an important component of Rio Grande cutthroat 
trout diet. Other subspecies of cutthroat trout become more piscivorous 
(fish eating) as they mature (Moyle 1976, p. 139; Sublette et al. 1990, 
p. 54) and cutthroat trout living in lakes will prey heavily on other 
species of fish (Echo 1954, p. 244). It is possible that native 
cyprinids (i.e., chubs, minnows, and dace) and suckers may have once 
been

[[Page 27903]]

important prey items for Rio Grande cutthroat trout. Growth of 
cutthroat trout varies with water temperature and availability of food. 
Most populations of Rio Grande cutthroat trout are found in high 
elevation streams. Under these conditions growth may be relatively slow 
and time to maturity may take longer than is seen in subspecies that 
inhabit lower elevation (warmer) streams.
    Typical of trout, Rio Grande cutthroat trout require several types 
of habitat for survival: spawning habitat, nursery or rearing habitat, 
adult habitat, and refugial habitat. Spawning habitat consists of clean 
gravel (little or no fine sediment present) that ranges between 6 to 40 
millimeters (mm) (0.24-1.6 inches (in)) (NMDGF 2002, p. 17). Nursery 
habitat is usually at the stream margins where water velocity is low 
and water temperature is slightly warmer. Harig and Fausch (2002, pp. 
542, 543) found that water temperature may play a critical role in the 
life history of the young-of-year cutthroat. Streams with mean daily 
temperature in July of less than 7.8 [deg]C (46 [deg]F) may not have 
successful recruitment (survival of individuals to sexual maturity and 
joining the reproductive population) or reproduction in most years. 
Adult habitat consists of pools with cover and riffles for food 
production and foraging. Refugial habitat in the form of large deep 
pools is also necessary for survival. The primary form of refugial 
habitat is deep pools that do not freeze in the winter and do not dry 
in the summer or during periods of drought. Lack of large pools may be 
a limiting factor in headwater streams (Harig and Fausch 2002, p. 543). 
Refugial habitat may also be a downstream reach of stream or a 
connected adjacent stream that has maintained suitable habitat in spite 
of adverse conditions.
    A technical review of Rio Grande cutthroat trout was recently 
completed (Pritchard and Cowley 2006) which covers the biology of the 
subspecies in greater detail and the reader is referred to that 
document for additional background information on the subspecies.

Summary of Factors Affecting the Subspecies

    Section 4 of the Act and regulations (50 CFR 424) promulgated to 
implement the listing provisions of the Act set forth the procedures 
for adding species to the Federal list of endangered or threatened 
species. A species may be determined to be threatened or endangered due 
to one or more of the five factors described in section 4(a)(1) of the 
Act. The following analysis examines the listing factors and their 
application to Rio Grande cutthroat trout.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

Population Isolation and Fragmentation

    The historic range of Rio Grande cutthroat trout has been greatly 
reduced over the last 150 years. Populations have been lost because of 
water diversions, stream drying, dams, habitat degradation, changes in 
hydrology, hybridization with rainbow trout, or competition with brown 
(Salmo trutta) and brook trout (Salvelinus fontinalis) (Pritchard and 
Cowley 2006, pp. 16, 34-37; 67 FR 39939). Quantifying the exact 
magnitude of loss in either number of fish or habitat is difficult 
because there are no baseline data. Alves et al. (2007, p. 26) estimate 
that conservation populations occupy about 10 percent of historically 
inhabited stream miles. Also, the current distribution of occupied 
miles on the landscape differs from the historical distribution. The 
range has contracted northward, Rio Grande cutthroat trout are now 
restricted primarily to headwater streams, and the large connected 
networks that once linked hundreds of stream miles together no longer 
exist. The change in distribution is discussed briefly followed by a 
discussion of fragmentation which has modified and curtailed habitat.
    Historically, 43 percent of Rio Grande cutthroat trout populations 
occupied streams 2,438 m (8,000 ft) or less in elevation (Alves et al. 
2007, p. 18). Currently, only about 1.6 percent of the populations are 
in streams less than 2,438 m (8,000 ft) (Alves et al. 2007, p. 18). 
Conservation populations, as defined above, are now concentrated in 
elevations from 2,743-3048 m (9,000-10,000 ft) (Alves et al. 2007, p. 
18). High-elevation streams (above 2,743 m (9,000 ft)) are subject to 
extreme and fluctuating environmental conditions including forest 
fires, freezing, and dewatering (Novinger and Rahel 2003, p. 779). In 
addition, headwater mountain streams often lack critical resources such 
as deep pools (Harig and Fausch 2002, p. 546) and provide insufficient 
refuge from catastrophic disturbance (Pritchard and Cowley 2006, p. 
17). Because high-elevation headwater streams are narrow and small 
compared to the larger downstream reaches that Rio Grande cutthroat 
trout once occupied, the absolute loss of habitat in both quantity and 
quality is greater than stream miles might indicate.
    Historically, many watersheds supporting Rio Grande cutthroat trout 
contained streams that were connected. For example, in Colorado, the 
Trinchera, Conejos, Culebra, Costilla, and Alamosa rivers would all 
have been connected through the upper Rio Grande, forming a vast 
network of streams (Alves et al. 2007, p. 10). As a consequence of 
habitat loss, each of these watersheds is now isolated from the other 
and Rio Grande cutthroat trout are restricted to fragments of streams 
(Alves et al. 2007, pp. 12, 29). Of the 120 conservation populations, 
112 (representing 80 percent of occupied miles) are in isolated stream 
fragments (Alves et al. 2007, p. 29). No populations are considered to 
have strong connectivity (i.e., >= 5 connected streams with open 
migration corridors) (Alves et al. 2007, pp. 29, 77). One population 
has a moderate degree of connectivity (4 to 5 connected streams); 
however, this watershed (Comanche Creek) is currently under restoration 
and has very few fish present. Seven populations have very little 
connectivity (2-3 connected streams, infrequent straying of adults may 
occur) (Alves et al. 2007, pp. 29, 77). Because Rio Grande cutthroat 
trout habitat is severely fragmented and because the effects of 
fragmentation are considered one of the primary threats to Rio Grande 
cutthroat trout populations, the consequences of fragmentation are 
discussed in detail below.
    Habitat fragmentation reduces the total area of habitat available, 
reduces habitat complexity, and prevents gene flow (Saunders et al. 
1991, p. 25; Rieman and McIntyre 1995, p. 293; Burkey 1995, pp. 527, 
528; Dunham et al. 1997, pp. 1126, 1127; Frankham et al. 2002, p. 310; 
Noss et al. 2006, p. 219). Fragmentation accelerates extinction, 
especially when movement of fish among fragments is not possible, as is 
the case with Rio Grande cutthroat trout (Burkey 1995, p. 540; Frankham 
et al. 2002, p. 314). Isolated populations are vulnerable to extinction 
through demographic stochasticity (random changes in the population 
structure, e.g., uneven male/female ratios); environmental 
stochasticity (random changes in the fishes' surroundings) and 
catastrophes (e.g., fires, stream drying, freezing); loss of genetic 
heterozygosity (genetic diversity) and rare alleles (inherited forms of 
a genetic trait); and human disturbance (Shaffer 1987, p. 71; Rieman et 
al. 1993, pp. 9-15; Burkey 1995, pp. 527, 528; Dunham et al. 1997, p. 
1130; Frankham et al. 2002, pp. 310-324). Completely isolated fragments 
are the most severe form of fragmentation

[[Page 27904]]

because the isolation prevents fish from mating with other fish 
carrying different genes, thereby preventing new genes from entering 
the isolated population (Frankham et al. 2002, p. 314). Of 120 Rio 
Grande cutthroat trout conservation populations, 112 (93 percent, 80 
percent of occupied miles) exist as isolated segments or have very 
little connectivity (Alves et al. 2007, p. 29).
    Apart from the isolation (lack of gene flow) that fragmentation 
causes, the short length of the fragments and small population size 
that they support are also of concern for Rio Grande cutthroat trout. 
Seventy-one percent of Rio Grande cutthroat trout conservation 
populations occupy stream segments of 8.1 km (5 mi) or less (median 6.2 
km (4.2 mi)) (Alves et al. 2007, p. 26). Several researchers have found 
that population viability of cutthroat trout is correlated with stream 
length (Hilderbrand and Kershner 2000, p. 515; Young et al. 2005, p. 
2405; Cowley 2007, DOI: 10.1002/aqc.845). Stream length is important 
because trout need a variety of habitats to complete their life cycle 
(i.e., spawning habitat, rearing habitat, adult habitat, refugial 
habitat) (Rieman and McIntyre 1995, p. 293; Horan et al. 2000, p. 1251; 
Harig and Fausch 2002, p. 546; Young et al. 2005, p. 2406). The shorter 
the stream, the more likely it is that one or more of the Rio Grande 
cutthroat trout's required habitats is either missing, or inadequate 
for completion of the species life cycle (Hilderbrand and Kershner 
2000, p. 513). This is particularly true in high-elevation streams 
which are narrower and shallower than larger, lower elevation, streams. 
The longer a stream is, the more complexity it encompasses and the 
higher the probability that no particular habitat type limits the 
population.
    Hilderbrand and Kershner (2000, p. 515) estimated 8.3 km (5.1 mi) 
were required to maintain a population of 2,500 cutthroat trout when 
fish abundance was high (0.3 fish/m (0.09 fish/ft)). Adding a 10 
percent loss rate, to account for emigration and mortality, increased 
the length up to 9.3 km (5.8 mi) in order to maintain 2,500 fish. For 
abundances of 0.2 fish/m (0.06 fish/ft) and 0.1 fish/m (0.03 fish/ft), 
the corresponding length increased to 12.5 km (7.8 mi) and 25 km (15.5 
mi), respectively (assuming no losses) (Hilderbrand and Kershner 2000, 
p. 15). Young et al. (2005, p. 2405) found that to maintain a 
population of 2,500 cutthroat trout, 8.8 km (5.5 mi) of stream were 
needed. Cowley (2007 DOI: 10.1002/aqc.845) determined that in stream 
widths of approximately 2 m (6.6 ft) (average width of most Rio Grande 
cutthroat trout streams), a stream length of 11 km (6.8 mi) would be 
needed to support a population of 2,750 fish. Because the majority (71 
percent) of Rio Grande cutthroat trout conservation populations occur 
in short stream fragments of 8.1 km (5 mi) or less, these studies 
indicate that stream fragmentation (resulting in short stream lengths) 
pose a threat to Rio Grande cutthroat trout conservation populations.
    Longer streams support larger populations (Harig and Fausch 2002, 
p. 546; Young et al. 2005, p. 2405). Population size is a major 
determinant of species persistence (Reed et al. 2003, p. 23). 
Population persistence decreases as population size decreases (Rieman 
and McIntyre 1993, p. 15). Long-term persistence of a population 
depends on having a sufficient number of individuals to avoid 
inbreeding depression, which decreases population viability, and to 
maintain genetic variation (Franklin 1980, pp. 135-148; Frankham et al. 
2002, pp. 190-192; Reed 2005, pp. 563, 564). Genetic variability within 
a population is necessary for adaptability (Reed 2005, p. 564; Cowley 
2007 DOI: 10.1002/aqc.845). Genetic variation will be lost through time 
in isolated populations and the loss occurs more quickly in small 
populations than in large populations (Rieman and Allendorf 2001, p. 
761). When a population is greatly reduced in size (bottlenecked), 
genetic diversity is decreased (Frankham et al. 2002, p. 183)
    In our previous status review (67 FR 39938), we concluded that a 
population size of 2,500 fish would ensure long-term persistence of Rio 
Grande cutthroat trout, i.e., would reduce the risks associated with 
small population size alone. Since that time other peer-reviewed 
literature has been published that allows us to further evaluate this 
number. Reed et al. (2003, p. 30), in a review of 102 vertebrate 
species, estimate that sufficient habitat should be present to allow 
for approximately 7,000 breeding age adults in order to ensure long-
term species persistence. Cowley (2007 DOI: 10.1002/aqc.845) found that 
a population size of 2,500 Rio Grande cutthroat trout failed to meet 
the desired long-term effective population size (number of adults 
actually contributing offspring to the population) of at least 500. A 
minimum population size of 2,750 was sufficient if there was infrequent 
loss of year classes (all the individuals of a population of fishes 
born or hatched in the same year). He found that a larger population 
size was required as survival rate of young fish (one year or less) 
decreased. He concluded that managing for Rio Grande cutthroat trout 
population sizes in the range of 8,000 to 16,000 would be more likely 
to ensure population viability when there are low to intermediate 
survival rates of young fish. While any population number we might use 
to assess the status of the subspecies is unlikely to satisfy all 
interested parties, we believe 2,500 continues to be a reasonable 
standard by which to evaluate the populations. While the range of 
acceptable standards may range from 2,500 to 16,000, there is relative 
certainty that populations below 2,500 are likely at risk and may not 
be contributing to long-term persistence of the subspecies.
    In 2007, fifteen of the 120 conservation populations had 2,500-
7,000 Rio Grande cutthroat trout. The 120 conservation populations 
occur in 161 individual streams. Several conservation populations 
occupy multiple individual stream segments that are connected, thus the 
numbers of occupied streams segments is larger than the total number of 
conservation populations. Of those 161 individual streams, a minimum of 
53 contain populations of under 500 reproducing adult fish. Because 
population estimates are unavailable for 38 streams, and most of the 38 
are short segments (2007 database), the total number of populations 
with fewer than 500 reproducing adult fish is much likely greater than 
53. Of the 99 conservation populations with quantitative estimates, 19 
have an abundance of 0-0.03 fish/m (0-50 fish/mi) and 31 have an 
abundance of 0.03-0.09 fish/m (50-150 fish/mi). These low abundances 
indicate that on average, Rio Grande cutthroat trout need longer, 
rather than shorter, stream segments to ensure their long-term 
persistence because longer streams support larger numbers of fish 
(Hilderbrand and Kershner 2000, p. 515).
    In 2002, we identified 13 Rio Grande cutthroat trout populations as 
secure (67 FR 39940). All 13 had populations over 2,500, contained no 
nonnative trout, and were protected from invasion by nonnative fish by 
a barrier. By 2007, 5 of these populations had fewer than 1,000 fish 
and 3 others had fewer than 2,000. One of the populations 
(approximately 13,000 fish in 2002) is thought to have been extirpated 
by low water effects (the stream either dried or froze). Brown trout 
were discovered above the barrier on one of the streams. The status of 
only 5 populations remained unchanged between 2002 and 2007.
    A ``general health assessment'' was used by Alves et al. (2007, pp. 
41-43)

[[Page 27905]]

to look at the health of individual populations. Sixty-eight 
populations (798 km (496 mi)) were judged to have a moderately high 
degree of health, 50 (264 km (164 mi)) moderately low, and 1 (3.2 km (2 
mi)) ranked as having low health (Alves et al. 2007, p. 42). Four 
factors were considered in the assessment: isolation, temporal 
variability (a measure of variability in the physical environment which 
correlates with stream length), population size, and population 
production (a composite score based on habitat condition, presence of 
nonnatives, and disease) (Alves et al. 2007, pp. 82, 83, 89). These 
factors were weighted in the following order: isolation (0.5), stream 
length (0.7), population size (1.2), and population production (1.6). 
The first 3 factors have a range of 1 to 4, while the last, population 
production, has a range of 2 to 8 (Alves et al. 2007, p. 89), 
effectively doubling its importance beyond the greater weighting (1.6) 
assigned to it. Rationale for the weighting scheme is not provided. 
Many scoring systems could be devised to determine population health 
and it is unclear why isolation and stream length, two factors that 
have been discussed extensively in conservation biology and cutthroat 
trout conservation literature (e.g., Saunders et al. 1991, pp. 18-26; 
Dunham et al. 1997, p. 1130; Hilderbrand and Kershner 2000, p. 513; 
Frankham et al. 2002, Chapter 13; Young et al. 2005, p. 2405; Noss et 
al. 2006, Chapter 7) were assigned the lowest weights. This rating 
system is heavily biased towards production and does not provide a 
balanced assessment of population health. However, even with this 
unbalanced health assessment, only one stream ranked as having high 
health, Comanche Creek. A major restoration of Comanche Creek began in 
2007, and while we fully expect it to be restocked with nonintrogressed 
Rio Grande cutthroat trout in the future, it has no Rio Grande 
cutthroat trout currently.
    It has been argued that small, isolated populations have persisted 
for decades (Patten and Sloane 2007, p. 3). However, Rio Grande 
cutthroat trout populations have only been monitored and intensively 
managed during the last 50 years or less, and habitat conditions and 
stressors are very different from historic conditions. Consequently, 
long-term persistence cannot be appropriately assessed. In addition, as 
Hilderbrand and Kershner state (2000, p. 517), although some isolated 
populations may have persisted for centuries, these populations are 
probably exceptions. To assume all isolated populations will behave 
similarly may lead to insufficient protection (Hilderbrand and Kershner 
2000, p. 517).
    Based on the arguments presented above, we determined that stream 
length, population size, and absence of nonnative trout are the most 
important criteria by which to evaluate long-term population 
persistence. We have evaluated the status of Rio Grande cutthroat trout 
conservation populations primarily on stream length (9.6 km (6 mi) or 
greater), population size (more than 2,500 fish), and presence or 
absence of nonnative fish (Tables 1 and 2). All streams with a length 
of over 9.6 km (6 mi) were initially evaluated. Stream miles in Tables 
1 and 2 include all miles in the conservation population when more than 
one stream is connected. Habitat condition and presence of a barrier 
are also presented in Tables 1 and 2 because these factors are also 
considered important in evaluating the status of the populations. Eight 
streams (4 in Colorado, 3 in New Mexico, one shared) currently have 
over 2,500 fish, are 9.6 km (6 mi) or longer, and have no nonnative 
fish present (Table 1). In addition, the main stem of these streams is 
greater than 1.5 m (5 ft) (although tributaries to the main stem may be 
less than this width) and all have abundances of 151 fish per mile or 
greater. Five of the streams, Cross, Medano, San Francisco, Canones, 
and El Rito creeks, were identified as secure in 2002. Although these 
eight streams meet the criteria, some have characteristics that are 
less than optimal (Table 1). For instance, habitat quality in Cross and 
Canones creeks is judged as ``Fair.'' In Canones Creek, the percentage 
of pools (9 percent) is low and it was found to be at risk by Santa Fe 
National Forest temperature standards (Ferrell 2006) (discussed in more 
detail in the ``Climate Change'' section below).

 Table 1.--Rio Grande Conservation Populations With Unaltered (< 1%) Genetic Status Occurring in Stream Lengths Greater Than 9.6 km (6 mi), With Greater
                                                     Than 2,500 Fish, and no Nonnative Trout Present
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Population     Length in km
                                         size            (mi)         Habitat condition          Ownership              State              Barrier
--------------------------------------------------------------------------------------------------------------------------------------------------------
San Francisco Creek...............           3,820     23.5 (14.6)  Excellent............  USFS, Private........  CO                Water diversion.
Torcido Creek.....................           6,042     16.7 (10.4)  Good.................  Private..............  CO                Drying.
Medano Creek......................           5,795     33.6 (20.9)  Excellent............  NPS, USFS............  CO                None.
Cross Creek.......................           3,675      12.9 (8.0)  Fair.................  BLM, USFS, Private...  CO                None.
Costilla Creek....................           5,200     21.1 (13.1)  Excellent............  Private..............  NM, CO            Temporary/Manmade.
Alamitos Creek....................           3,080      11.4 (7.1)  Good.................  USFS.................  NM                Partial/Water
                                                                                                                                     diversion.
El Rito Creek.....................           4,401      10.3 (6.4)  Good.................  USFS.................  NM                Temporary/Manmade.
Canones Creek.....................           3,683       9.7 (6.0)  Fair.................  USFS.................  NM                Waterfall.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Table 2 shows all the other Rio Grande cutthroat trout conservation 
populations in stream lengths greater than 9.6 km (6 mi). Six of the 
populations have more than 2,500 Rio Grande cutthroat trout, but all of 
these have nonnative brook trout present as well. In addition, 4 of 
these have habitat quality judged as fair and one is in a stream with a 
width less than 1.5 m (5 ft) wide, which puts it at risk for drying (as 
discussed below). Abundance (fish per mile) is provided in Table 2 
because some of these have less than 150 fish per mile, and, as 
mentioned above, for populations with 0-50 or 50-150 fish per mile, a 
longer stream length would be needed to ensure long-term persistence. 
It should also be noted that Sangre de Cristo Creek has tested positive 
for whirling disease. For all of these reasons, although the Rio Grande 
cutthroat conservation populations presented in Table 2 occur in stream 
lengths greater than 9.6 km (6 mi), all appear at risk for one or more 
reasons. Two additional streams (Osier and Cascade) have strong 
populations 3,239 and 2,372, respectively, with no nonnative trout 
present. However, stream length for Osier Creek is only 5.9 km (3.7 mi) 
and for Cascade it is 4.7 km (2.9 mi). While these populations do 
currently contribute to the status of the subspecies range-wide, they 
are considered too short to ensure long-term

[[Page 27906]]

persistence as their shorter length makes them more vulnerable to 
extirpation from ash flow or other localized disturbance.

   Table 2.--Rio Grande Conservation Populations in Stream Lengths Greater Than 9.6 km (6 mi), Sorted by Population Size. Nonnative Species May Be Present or Absent. BRK = Brook Trout, BRN =
                                                                                 Brown Trout, WS = White Sucker
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Abundance (fish per   Length in km
           Stream name                Population size            mile)              (mi)        Nonnatives present    Habitat  condition     Width in feet         State           Barrier
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Jacks Creek......................  4,849...............  > 400...............     18.5 (11.5)  BRK.................  Fair...............  < 5................  CO            Drying.
Cabresto Creek...................  4,570...............  > 400...............      13.7 (8.5)  BRK.................  Fair...............  5 to 10............  NM            Diversion.
Sangre de Cristo Creek...........  3,793...............  151 to 400..........     36.2 (22.5)  BRK.................  Fair...............  5 to 10............  CO            Partial/Diversion.
South Carnero Creek..............  3,748...............  151 to 400..........     22.9 (14.2)  BRK, BRN, WS........  Fair...............  10 to 15...........  CO            None.
West Indian Creek................  3,345...............  151 to 400..........     17.1 (10.6)  BRK.................  Excellent..........  5 to 10............  CO            Manmade dam.
Trinchera Creek..................  2,941...............  151 to 400..........      14.5 (9.0)  BRK.................  Excellent..........  10 to 15...........  CO            None.
Polvadera Creek..................  2,045...............  151 to 400..........      12.1 (7.5)  None................  Poor...............  < 5................  NM            Waterfall.
Jacks Creek......................  1,504...............  151 to 400..........      11.3 (7.0)  None................  Good...............  5 to 10............  NM            Temporary/Manmade.
Jim Creek........................  1,283...............  151 to 400..........      10.0 (6.2)  BRK.................  Poor...............  5 to 10............  CO            None.
Ute Creek........................  1,260...............  50 to 150...........      13.8 (8.6)  None................  Good...............  5 to 10............  NM            None.
Rio de Truchas...................  692.................  50 to 150...........      10.5 (6.5)  None................  Fair...............  5 to 10............  NM            Diversion.
Little Vermejo Creek.............  680.................  50 to 150...........      11.9 (7.4)  BRK.................  Excellent..........  5 to 10............  NM            Temporary/Manmade.
Vallejos Creek...................  678.................  50 to 150...........      11.7 (7.3)  BRN.................  Good...............  10 to 15...........  CO            None.
Cave Creek.......................  411.................  50 to 150...........      10.1 (6.3)  BRK, BRN, WS........  Fair...............  5 to 10............  CO            None.
East Pass Creek..................  369.................  50 to 150...........      11.1 (6.9)  None................  Fair...............  < 5................  CO            Drying.
Middle Carnero Creek.............  344.................  < 50................      11.3 (7.0)  WS..................  Fair...............  < 5................  CO            Manmade dam.
Ricardo Creek....................  271.................  50 to 150...........      14.5 (9.0)  BRK.................  Good...............  5 to 10............  CO            Temporary/Manmade.
Torsido Creek....................  250.................  50 to 150...........      10.3 (6.4)  BRK.................  Poor...............  < 5................  CO            None.
Wagon Creek......................  246.................  151 to 500..........     20.9 (13.0)  BRK.................  Good...............  5 to 10............  CO            Partial/Diversion.
McCrystal Creek..................  236.................  < 50................      15.1 (9.4)  None................  Good...............  5 to 10............  NM            Temporary.
South Ponil Creek................  202.................  < 50................      15.3 (9.5)  None................  Good...............  5 to 10............  NM            Temporary/Manmade.
Rio de Oso.......................  194.................  < 50................      12.4 (7.7)  None................  Fair...............  < 5................  NM            None.
Capulin Creek....................  186.................  < 50................      11.9 (7.4)  None................  Excellent..........  5 to 10............  NM            Drying.
North Fork Carnero Creek.........  97..................  < 50................      13.0 (8.1)  WS..................  Fair...............  < 5................  CO            Manmade dam.
Cat Creek........................  Unknown.............  Unknown.............      15.1 (9.4)  None................  Fair...............  < 5................  CO            Drying.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Habitat fragmentation is a threat that can be partially alleviated 
by management activities. Three major watershed-scale projects have 
been initiated on both private and USFS lands and are in various phases 
of implementation. A joint project between Vermejo Park Ranch and the 
states of Colorado and New Mexico to restore the Costilla Creek 
watershed began in 2002 (Patten et al. 2007, pp 95-102). The 
restoration removed brook trout, brown trout, and introgressed 
cutthroat trout and reintroduced Rio Grande cutthroat trout into 
Costilla Creek, 2 tributaries, and 3 small lakes, totaling 22 km (13.6 
miles) of stream and 9.5 ha (23.5 ac) of lake (project is discussed 
further in the ``Fisheries Management'' section below). As part of the 
larger Costilla Project, 34 km (21.1 mi) of Comanche Creek and selected 
tributaries were chemically treated with piscicides (chemicals that 
kill fish) in 2007. Most likely a second treatment will be required and 
will be completed in 2008 before Rio Grande cutthroat trout are stocked 
back into the watershed. A draft Candidate Conservation Agreement with 
Assurances with private landowners has been drafted so that the 
Costilla Creek project can be extended downstream. Successful 
implementation of this project would lead to the restoration of 
approximately 241 km (150 mi) and 25 lakes (Patten and Sloane 2007, p. 
7). The Placer watershed in Colorado also underwent chemical treatment 
in 2007. This watershed has the potential for approximately 80.5 km (50 
mi) of connected stream. If successful, the Costilla and Placer 
watersheds would represent substantial gains in the goal of creating 
connected stream systems for Rio Grande cutthroat trout.
    While watershed restoration can reconnect streams and is the best 
method for addressing fragmentation, major restoration projects face 
many challenges including: negative public sentiment towards using 
piscicides in streams which slows or stops projects (Patten et al. 
2007, p. 102), incomplete treatment which leaves nonnatives present, 
sabatoge of the treatment area (unauthorized introduction of nonnative 
trout) (Japhet et al. 2007, p. 17), subsequent barrier failure which 
allows nonnatives to reinvade a system (Japhet et al. 2007, p. 15), and 
inadvertent mistakes. While many stream segments have been restored and 
the Costilla and Placer watershed projects are in progress, no major 
watershed restorations have been completed.
    The Service has evaluated the data presented by Alves et al. (2007) 
and supplemental information requested related to the database. Based 
on our knowledge of Rio Grande cutthroat trout populations that we 
previously classified as secure in 2002, and all of the information 
available to us we conclude:
    (1) The majority of Rio Grande cutthroat trout populations (93 
percent) are in isolated fragments less than 8 km (5 mi) long (71 
percent);
    (2) Populations are concentrated in high elevation (2,438 to 3,048 
m (8,000 to 10,000 ft)) headwater streams that provide marginal 
habitat, especially in regards to the number and depth of pools 
critical for trout survival in times of environmental extremes;
    (3) The drought in the early 2000s had resulted in adverse effects 
on several populations (discussed in more detail in the ``Climate 
Change'' section below);
    (4) Eight of 13 populations we had identified as secure in 2002 
would no

[[Page 27907]]

longer meet the criteria we used at that time (67 FR 39937); and
    (5) Only eight populations currently meet our revised criteria for 
long-term persistence.

Although additional populations may have greater than 2,500 fish or are 
in streams longer than 9.6 km (6 mi), there are additional significant 
threats to those populations that put their long-term persistence in 
question. For these reasons, we find that Rio Grande cutthroat trout is 
threatened by fragmentation, isolation, and loss of habitat throughout 
its range. While watershed restoration may alleviate this threat in the 
future, insufficient progress has been made to alleviate the threat of 
fragmentation range-wide at this time.

Habitat Condition

    Many Rio Grande cutthroat trout conservation populations currently 
occupy lands administered by Federal agencies. Of the total 1,110 km 
(690 mi) of occupied habitat, 698 km (434 mi) (63 percent) are under 
Federal jurisdiction, with the majority (59 percent) occurring within 
National Forests (Alves et al. 2007). Rio Grande cutthroat trout occupy 
6.1 km (3.8 mi) of land administered by the BLM, 30.5 km (19 mi) 
managed by the National Park Service, and 397 km (247 mi) that are 
owned privately.
    Land uses associated with each conservation population were 
identified in Alves et al. (2007, p. 49, Table 33), but the impact of 
the activities was not evaluated in relation to individual populations 
or the conservation of the subspecies. Non-angling recreation (e.g., 
camping, hiking, ATV use, etc.) occurs in 90 percent of the 
conservation populations, and angling occurs in 84 percent of the 
conservation populations. Livestock grazing occurs within the zone of 
influence (area around the stream in which activities influence stream 
habitat) of 87 percent of the conservation populations, roads in 58 
percent, timber harvest in 19 percent, dewatering in 17 percent, and 
mining in 3 percent. Only 3 populations (3 percent) were judged as 
having no land use activities within a zone that would influence the 
stream habitat. Many populations have more than one land use occurring 
in the area.
    An evaluation of habitat quality was conducted for currently 
occupied habitat (Alves et al. 2007, p. 20). The evaluation considered 
both natural habitat features and human disturbances, including land 
use practices. A stream ranked excellent if it had ample pool habitat, 
low sediment levels, optimal temperatures, and quality riparian 
habitat. Good habitat quality had some attributes that are less than 
ideal, and fair habitat has a greater number of attributes that are 
less than ideal. Poor habitat quality is found where most habitat 
attributes reflect inferior conditions. Approximately 224 km (139 mi) 
(20.2 percent of occupied habitat) received an excellent habitat 
rating. Good habitat conditions were found in 426 km (265 mi) of 
habitat (38.4 percent of occupied habitat), and fair habitat conditions 
were found in 335 km (208 mi) of habitat (30.1 percent of occupied 
habitat). Poor conditions were found in 35 km (22 mi) (3.2 percent of 
occupied habitat), and habitat conditions in 90 km (56 mi) (8.1 
percent) were unknown (Alves 2007, p. 2). The majority of occupied 
habitat (58.6 percent) is considered in good or excellent condition 
(Alves et al. 2007, p. 20).
    The Service also reviewed 19 detailed stream survey reports which 
were conducted by the Santa Fe and Carson national forests in the 
period 2001-2006. Although these surveys represent only about one 
quarter of the conservation populations in New Mexico (19 of 84 
populations), both large (i.e., Pecos River, Rio de las Vacas, Comanche 
Creek) and small (i.e., Yerba, Manzanita creeks) streams are 
represented. Therefore, these surveys provide additional insight into 
the habitat condition on USFS lands. Of the 19 streams surveyed, the 
most consistent problem is lack of pool habitat. Of the 19 streams, 18 
had less than the 30 percent pool habitat (range 1-21 percent) needed 
to be considered properly functioning trout streams. For eight of these 
streams, a target value of 30 percent pool habitat was not considered 
appropriate because they were 1st or 2nd order streams (i.e., headwater 
streams) which often have few pools naturally because they occur on 
high gradient slopes. But for four of these eight streams, the pool 
habitat ranged from 1-3 percent and the reports noted that even for 
headwater streams this was an insufficient number of pools.
    In most streams (16 of 19) the average residual pool volume, which 
represents initial pool depth if the stream were to dry, met the USFS 
standard of 0.3 m (1 ft) or greater. However, the deepest average 
residual pool volume was only 0.67 m (2.2 ft) and the mean depth of 
pools for all 19 streams was 0.39 m (1.3 ft), indicating that the 
majority of pools are relatively shallow.
    Pools are recognized as important overwintering habitat and also 
are holding areas for trout when streams dry. Not only are the number 
of pools consistently fewer than desirable, but they are also 
relatively shallow, and thus provide limited refugial habitat in times 
of stream freezing or drying. Lack of deep pools could affect year-
class survival. As noted by Cowley (2007 DOI: 10.1002/acq.845) loss of 
a year class of fish would suggest that longer stream length is needed 
to provide adequate habitat for long-term population persistence. 
However, as mentioned above, the sample size (19 streams) is relatively 
small and it is not known if the results accurately represent Rio 
Grande cutthroat trout streams range-wide.
    Livestock grazing occurs in the vicinity of 87 percent of the Rio 
Grande cutthroat trout populations (Alves 2007, p. 49). We recognize 
that improper grazing does cause adverse impacts (e.g., loss of cover, 
increased sedimentation, loss of riparian vegetation) to some 
individual populations of Rio Grande cutthroat trout, especially during 
drought conditions when the cattle tend to concentrate in riparian 
areas. While a few of the USFS stream surveys noted that impacts by 
cattle (or elk) were causing localized problems, grazing was not cited 
as causing damage throughout the length of any stream. Specific 
information on grazing impacts to Rio Grande cutthroat trout habitat on 
a range-wide basis is not available. We have no information that leads 
us to conclude that improper grazing is a significant threat to Rio 
Grande cutthroat trout range-wide.
    Timber harvest and associated road building has also led to the 
deterioration of Rio Grande cutthroat trout habitat. However, timber 
harvest in the National Forests has declined appreciably in the last 20 
years. As an example, on the two forests in New Mexico that have 
conservation populations, the Santa Fe National Forest and Carson 
National Forest, there has been a total of 3.2 ha (8 ac) clear cut 
since 1995 (Fink 2008 pp. 2, 3). The average amount of timber cut per 
year from 1984 to 1994 in these forests was 27.6 and 19 million board 
feet (MBF), respectively. From 1995 to 2005, the average amount cut per 
year was 3.5 and 0.09 MBF, respectively (Fink 2008, pp. 2, 3). While 
the effects of past logging practices may still be evident on the 
landscape in some locations, we conclude that timber harvest is not 
currently a threat to Rio Grande cutthroat trout populations.
    Roads and off-road vehicles can have negative impacts on stream 
habitat primarily through increased sedimentation which degrades 
spawning habitat. Non-angling recreation (which includes hiking and 
camping as well as off-road vehicle use) is present near 90 percent of 
the

[[Page 27908]]

conservation populations. On November 9, 2005, the USFS published 
revised rules regarding travel management on their lands (70 FR 68264). 
One of the primary purposes of the rule is to protect natural 
resources. The final rule requires the designation of roads, trails, 
and areas that are open to motor vehicle use by class of vehicle and, 
if appropriate, time of year. Use of motor vehicles off designated 
routes will be prohibited (70 FR 68264). The Service has begun 
consultation on the Travel Management Plans proposed by National 
Forests in USFS Region 3 (Arizona and New Mexico) and protecting 
aquatic resources is an important component of these plans. While roads 
have been identified as an area of concern for some streams (e.g., Tio 
Grande, Rio Grande del Rancho, Martinez 2001, 2002), we conclude that 
roads are not a threat to Rio Grande cutthroat trout populations range-
wide.
    Management agencies are actively working towards improving habitat 
conditions for Rio Grande cutthroat trout. In addition to the travel 
management rule on USFS lands, several projects have been completed 
recently to address habitat degradation caused by roads. For example, 
grant money was obtained and used to inventory and identify 97 road 
improvement projects to reduce sediment input into Comanche Creek 
(Martinez 2006, p. 5). Six culverts were installed or realigned and ten 
sediment traps and energy dissipaters were installed below culvert 
spillways. Culverts that drained directly into Comanche Creek were 
removed. Abandoned logging roads were stabilized and unneeded roads 
were re-contoured to natural slope and re-vegetated (USFS 2006, pp.18-
19). In 2006, on the Santa Fe National Forest, over 1,829 m (6,000 ft) 
of buck and pole fence was constructed to improve traffic control and 
enforce an off-road vehicle closure around Rio Cebolla. Approximately 
17.7 km (11 mi) of stream and riparian habitat was protected by this 
project (USFS 2006, p. 12). On the Rio Grande National Forest, road-
stream crossing inventories and assessments were conducted for all 
streams with conservation populations to determine if the culverts were 
barriers to fish (USFS 2006, p. 4). Most of the 120 conservation 
populations (90 percent) have one or more restoration, conservation, or 
management activities either completed or currently being implemented 
(Alves et al. 2007, p. 60).
    Range-wide habitat quality is still difficult to accurately assess. 
Although an insufficient amount of pool habitat exists on the majority 
of streams sampled by the USFS in New Mexico, we cannot draw the same 
conclusion range-wide at this time because of lack of data. Alves et 
al. (2007 database) did not identify a lack of pools as a systematic 
problem. While land management practices have clearly improved and have 
less direct impact on Rio Grande cutthroat trout streams, some streams 
are still recovering from past land management practices. Therefore we 
conclude that there is insufficient information to indicate that 
habitat quality currently is a significant threat to Rio Grande 
cutthroat trout rangewide.

Nonnative Species

    The introduction of nonnative trout is widely recognized as one of 
the leading causes of range reduction in cutthroat trout subspecies 
(Griffith 1988, pp. 134, 137; Lassuy 1995, p. 394; Henderson et al. 
2000, pp. 584, 585; Dunham et al. 2002, p. 374; Peterson et al. 2004, 
p. 769). Dunham et al. (2004) provide an overview of the impact of 
nonnatives on headwater systems in North America. Since the late 1800s, 
fishery managers introduced nonnative salmonids (trout and salmon 
species) into lake and stream habitats of Rio Grande cutthroat trout. 
Nonnative rainbow, brook, brown trout and Yellowstone cutthroat trout 
have been introduced extensively throughout the range of Rio Grande 
cutthroat trout, and they compete (brook and brown trout) and hybridize 
(rainbow and other cutthroat subspecies) with Rio Grande cutthroat 
trout. Forty-six of 120 conservation populations (38 percent) have 
nonnative trout present (2007 database). When Rio Grande cutthroat 
trout occur in the same stream as nonnative trout, Rio Grande cutthroat 
trout typically occupy the colder, headwater reaches and the nonnative 
trout occupy areas downstream (Griffith 1988, p. 135; Dunham et al. 
1999, p. 885).
    Competition from nonnative trout, especially brook trout, is 
recognized as a threat to Rio Grande cutthroat trout (Behnke 2002, p. 
147; Peterson et al. 2004, pp. 768, 769). When brook trout invade 
streams occupied by cutthroat trout, the native cutthroat trout decline 
or are displaced (Griffith 1988, p. 136; Harig et al. 2000, pp. 994, 
998, 999; Dunham et al. 2002, p. 378; Peterson et al. 2004, p. 769; 
Young and Guenther-Gloss 2004, p. 193; Fausch et al. 2006, p. 6). Brook 
trout are the most common nonnative trout sympatric (co-occurring) with 
Rio Grande cutthroat trout populations in Colorado (2007 database). 
Brook trout reduce recruitment of cutthroat trout and reduce inter-
annual survival of juveniles, leading to a reduction in population size 
(Peterson et al. 2004, p. 769). Experiments where brook trout were 
removed from cutthroat trout populations showed an increase in the 
survival of juvenile cutthroat trout (Peterson et al. 2004, p. 767). 
Paroz (2005, p. 22) found that mean density and relative weight of Rio 
Grande cutthroat trout were lower in populations sympatric with brook 
trout. Several Rio Grande cutthroat trout conservation populations have 
been identified as at risk and declining because of brook trout (Alves 
et al. 2002, pp. 1-4).
    In New Mexico, brown trout is the most common nonnative trout 
present in Rio Grande cutthroat trout conservation populations 
(summarized from 2007 database). Not only are brown trout piscivores 
(feed on other fish), but they have also been shown to compete with Rio 
Grande cutthroat trout for resources such as food and space. Research 
has shown that Rio Grande cutthroat trout confined with brown trout 
grew significantly less, while the brown trout grew significantly more, 
than control fish (Shemai et al. 2007, pp. 315, 320, 321). A similar 
result was seen in experiments conducted with Bonneville cutthroat 
trout and brown trout (McHugh and Budy 2005, p. 2788). These results 
indicate that brown trout represent a threat to Rio Grande cutthroat 
trout from competition as well as predation (Paroz 2005, p. 34).
    The primary threat to Rio Grande cutthroat trout from rainbow trout 
and other cutthroat trout subspecies is through hybridization and 
introgression (Rhymer and Simberloff 1996, pp. 83, 97). The genetic 
distinctiveness of Rio Grande cutthroat trout can be lost through 
hybridization (Allendorf et al. 2004, p. 1205). Of the 120 conservation 
populations, 95 (79 percent) range-wide have been tested and are less 
than 1 percent introgressed (Alves et al. 2007, p. 31). These 
nonintrogressed populations occupy 870 km (541 mi), or 78 percent, of 
the 1110 km (690 mi) occupied by conservation populations (Alves et al. 
2007, p. 31). Another 161 km (100 mi) are occupied by populations that 
are 90-99 percent genetically pure, and 104 km (65 mi) are occupied by 
populations that have not been tested but are connected to 
nonintrogressed populations and have no record of stocking (Alves et 
al. 2007, p. 34).
    To minimize the contact of nonnative trout with Rio Grande 
cutthroat trout, barriers have been constructed where natural barriers 
didn't already exist in order to prevent nonnatives from invading. 
Alves et al. (2007, pp. 35, 36)

[[Page 27909]]

rated the genetic risk to the 120 conservation populations. A 
combination of barrier condition or presence and distance to 
hybridizing species, determined if a population was at moderate or low 
risk (Alves et al. 2007, p. 80). Populations protected by a complete 
barrier fell into the no risk category. They determined that 80 had no 
risk of genetic mixing with nonnative trout, 32 were at moderate risk, 
and 4 were at low risk. As mentioned earlier, four populations that 
Alves et al. (2007, pp. 35, 36) consider conservation populations are 
sympatric with a hybridizing species, and, therefore, we consider them 
at high risk.
    Since 2002, NMDGF and CDOW visited approximately 40 and 50 Rio 
Grande cutthroat trout conservation populations, respectively, to 
assess barrier presence and condition. Seven new barriers have been 
installed since 2002, and maintenance was done on at least eight 
(Japhet et al. 2007, pp. 24, 25; Patten et al. 2007, pp. 6, 11, 12, 16, 
17, 53). Both agencies have also mechanically and chemically removed 
nonnative trout from Rio Grande cutthroat trout streams. NMDGF removed 
nonnatives from 11 streams, and CDOW removed them from two (Patten and 
Sloane 2007, p. 5; Japhet et al. 2007, p. 26).
    Since 2002, CDOW and NMDGF have also proactively pursued genetic 
testing of Rio Grande cutthroat trout populations using the best 
technologies available. In many instances, the results confirmed 
previous assessments of genetic purity, while in other cases 
populations were either upgraded or downgraded (Japhet et al. 2007, pp. 
46-47; Patten et al. 2007, pp. 43-45). Diagnostic markers for 
Yellowstone cutthroat trout were also identified, which has led to more 
refined testing and more confidence in the categorization of the 
populations. The most recent results were used in the 2007 database. 
Results of the testing can be found in peer-reviewed literature (e.g., 
Pritchard et al. 2007a, Pritchard et al. 2007b) and in reports to the 
States (e.g., Pritchard and Cowley 2005).
    Approximately 38 percent of Rio Grande cutthroat trout conservation 
populations co-occur with nonnative trout (2007 database). Competition, 
predation, and hybridization with nonnative trout are considered an 
important source of stress that can depress Rio Grande cutthroat trout 
population numbers or, under the right circumstances, displace them 
(Fausch et al. 2006, pp. 9, 10). Although resource agencies remove 
nonnative trout through electrofishing when they co-occur with 
cutthroat trout subspecies, seldom if ever is complete removal possible 
(Patten et al. 2007, p. 104). Peterson et al. (2004, p. 769) show that 
over 90 percent of the brook trout population must be removed each year 
for 3 consecutive years to allow a large cohort of Colorado River 
cutthroat trout to survive from age 0 to age 2. This level of effort 
has not been documented for stream segments occupied by Rio Grande 
cutthroat trout populations (e.g., Japhet et al. 2007, p. 26).
    The Service concludes that nonnative fish are a threat to Rio 
Grande cutthroat trout range-wide based on the following facts:
    (1) Approximately 38 percent of the conservation populations have 
nonnative trout present;
    (2) Nonnative fish are a documented threat to Rio Grande cutthroat 
trout populations;
    (3) Mechanical removal cannot remove all of the nonnative fish;
    (4) The level of effort required to reduce brook trout populations 
to levels sufficient for survival of young Rio Grande cutthroat trout 
is not currently being conducted; and,
    (5) The number of streams that need regular treatment exceeds the 
capability of resource managers at their current staffing levels.

Drought

    The relatively short-term drought of the early 2000s negatively 
impacted or extirpated 14 Rio Grande cutthroat trout populations in 
Colorado and New Mexico (Japhet et al. 2007, pp. 42-44; Patten et al. 
2007, pp. 14-40). A fifteenth population is thought to have been 
extirpated in 2006 by complete freezing caused by low flow in the 
winter (Ferrell 2006, p. 11). The number of streams impacted may have 
been greater, because managers only survey a fraction of the 120 
conservation populations in any given year.
    We assume that small streams (1.5 m (5 ft) wide or less) are more 
susceptible to drying, increased water temperatures, and freezing than 
larger ones and that stream width is an indicator of risk. Decreased 
stream flow reduces the amount of habitat available for aquatic 
species, and water quality (e.g., temperature, dissolved oxygen) may 
become unacceptable in declining flow. Approximately 27 conservation 
populations are in streams that are 1.5 m (5 ft) or less in width 
throughout their entire length (2007 database). An additional 29 stream 
segments that are tributaries to the conservation populations are also 
less than 1.5 m (5 feet) in width (2007 database). Although not all 
small streams have equal risk, small headwater streams, especially 
those with an inadequate number of deep pools, are most likely to lose 
suitable habitat. Even if streams do not dry (or freeze) completely, 
stream length can be truncated during drought and many fish can perish, 
greatly reducing the population number (bottleneck) and reducing 
genetic diversity (Frankham et al. 2002, p. 183).
    Because of the documented extirpation and population reductions of 
Rio Grande cutthroat trout caused by drought, the possibility of more 
widespread drought accompanying climate change, and the lack of a 
range-wide plan to address drought, we conclude that drought is a 
threat to Rio Grande cutthroat trout throughout its range (discussed in 
``Climate Change'' section below).

Fire

    Wildfires are a natural disturbance in forested watersheds. 
However, since the mid-1980s, wildfire frequency in western forests has 
nearly quadrupled compared to the average frequency during the period 
1970-1986. The total area burned is more than six and a half times the 
previous level (Westerling et al. 2006, p. 941). In addition, the 
average length of the fire season during 1987-2003 was 78 days longer 
compared to that during 1970-1986 and the average time between fire 
discovery and control was 29.6 days longer (Westerling et al. 2006, p. 
941). Westerling et al. (2006, p. 942) found that wildfire sensitivity 
was related to snowmelt timing with 56 percent of fires and 72 percent 
of burned area occurring in early snowmelt years. Early spring snowmelt 
is strongly associated with spring temperature (Stewart et al. 2004, p. 
218; Westerling et al. 2006, p. 942). Westerling et al. (2006, p. 942) 
conclude that there are robust statistical associations between 
wildfire and climate in western forests and that increased fire 
activity over recent decades reflects responses to climate change 
(discussed further in the ``Climate Change'' section below).
    In the Southwest, the fire season is followed by the monsoon season 
(July to August). Consequently, denuded watersheds are susceptible to 
heavy precipitation leading to severe floods and ash flows. Although 
fish may survive the fire, ash and debris flows that occur after a fire 
can eliminate populations of fish from a stream (Rinne 1996, p. 654; 
Brown et al. 2001, p. 142; USFS 2006, p. 32; Patten et al. 2007, p. 
33), and the fire suppression activities (e.g., fire retardant, water 
removal, road construction) may also impact stream ecosystems (Buhl and 
Hamilton 2000, pp. 410-416; Backer et al. 2004, pp. 942,

[[Page 27910]]

943). Wildfires within the range of Rio Grande cutthroat trout have 
impacted or eliminated fish populations (Japhet et al. 2007, p. 20; 
Ferrell 2006, p. 32; Patten et al. 2007, pp. 33, 36), and the effects 
of large fires are recognized as a threat to greenback cutthroat 
(Oncorhynchus clarki stomias) populations in Colorado (Young and 
Guenther-Gloss 2004, p. 194). Imperiled fish populations can be rescued 
if ash flows are imminent, but a rescue and evacuation plan should be 
in place (e.g., Brooks 2004, pp. 1-15).
    Dunham et al. (2007, p. 342) found significantly elevated stream 
temperatures for at least a decade after a stand-replacing wildfire 
because of the lack of stream shading. In addition, the authors suggest 
that longer term (over 20 years) increases in stream temperatures are 
likely in systems where debris flows or severe floods completely 
eliminate streamside vegetation and reorganize the channel. Rainbow 
trout were found to be resilient and recolonized the burned streams 
within 1 year of extirpation in spite of elevated water temperatures 
(Dunham et al. 2007, p. 343). Dunham et al. (2003a, pp. 188, 189) 
suggest that fire poses a greater threat to fish populations when 
habitat is fragmented. Moyle and Light (1996, p. 157) argue that 
habitat degradation favors nonnative fishes and that species with 
narrow habitat requirements are expected to be more sensitive to 
habitat alteration caused by fire than generalist species such as 
rainbow trout (Dunham et al. 2003a, p. 189).
    Fire risk can be reduced through fuels reduction and prescribed 
burns. The National Forests in New Mexico have active programs to 
improve forest health. As an example, 28,314 ha (69,965 ac) have 
undergone fuel-reduction treatment, thereby improving watershed 
conditions associated with 100 km (62 miles) of stream, and an 
additional 58,912 ha (145,575 ac) are planned for treatment to improve 
conditions associated with an additional 128 km (79.5 mi) of stream 
(Ferrel 2002, p. 12). Such techniques have been found to reduce fire 
severity even under extreme weather conditions in low-elevation 
ponderosa pine forests (Schoennagel et al. 2004, p. 669). However, for 
mid-elevation, mixed-severity fire regimes, fuel-reduction treatments 
had virtually no effect on the 2002 Hayman Fire (Colorado), and extreme 
climate can override the influence of stand structure and fuels on fire 
behavior (Schoennagel et al. 2004, pp. 672, 673). Climate variation, 
not fuel levels, is seen as the dominant influence on fire frequency 
and severity in subalpine forests (Schoennagel et al. 2004, p. 666).
    Wildfires that eliminate nonnative fish provide the opportunity to 
reclaim streams for Rio Grande cutthroat trout. The 1996 Dome Fire in 
the Jemez Mountains (Santa Fe National Forest) extirpated the fish 
residing in Capulin Canyon. In 2006, after 10 years of habitat 
recovery, 100 Rio Grande cutthroat trout from Canones Creek were 
stocked into Rio Capulin adding 11.2 km (7.0 mi) of occupied habitat in 
New Mexico (Patten et al. 2007, p. 94). In addition, ash flows after 
the 2004 Peppin Fire in the Capitan Wilderness (Lincoln National 
Forest) apparently eliminated all fish from Pine Lodge Creek and 
Copeland Creek (Patten et al. 2007, pp. 255-258), and there are plans 
to restore Rio Grande cutthroat trout into these streams. Restoration 
of Pine Lodge Creek would add approximately 4 km (2.5 mi) of habitat in 
the Pecos Headwaters GMU (Patten et al. 2007, p. 255).
    Although we recognize that Rio Grande cutthroat trout evolved in a 
landscape that included fire, wildfire intensities and size are likely 
changing because of increased fuel loads and possibly climate change 
(see ``Climate Change'' section below). Wildfire today is much more of 
a threat than it was historically to Rio Grande cutthroat trout because 
of existing habitat loss, fragmentation, and climate change. These 
multiple stressors may overwhelm the subspecies' resilience to 
disturbance such as fire (Rieman et al. 2005, pp. 2, 3). Although fire 
may also provide opportunity for repatriation of Rio Grande cutthroat 
trout by eliminating nonnative fish, total elimination of nonnative 
fish from fire-affected streams is not guaranteed, and it may take many 
years for the habitat to become suitable. For these reasons, we 
conclude that wildfire is a significant threat to Rio Grande cutthroat 
trout throughout its range.

Summary of Factor A

    In summary, Rio Grande cutthroat trout populations have been and 
continue to be impacted by habitat fragmentation and isolation, 
nonnative species interactions, drought, and fire. Rio Grande cutthroat 
trout conservation populations occupy a fraction of their historical 
habitat, they are confined primarily to small high-elevation streams 
with marginal habitat, they are highly fragmented, and the stream 
segments they occupy are short in length. All of these factors work to 
reduce gene flow between populations and reduce the ability of 
populations to recover from catastrophic events thus threatening their 
long-term persistence. Detailed habitat surveys, although not available 
range-wide, are uniformly consistent in documenting a lack of pools in 
streams occupied by Rio Grande cutthroat trout. Deep pools are 
considered a critically important element of Rio Grande cutthroat trout 
habitat. As discussed above, in order to ensure some level of 
population stability and contribute to the long-term persistence of the 
subspecies, populations should consist of more than 2,500 fish, occupy 
9.6 km (6 mi) of stream or more, and have no nonnative trout present. 
Currently, only eight Rio Grande cutthroat trout populations meet these 
criteria. Nonnative trout co-occur with 38 percent of Rio Grande 
cutthroat trout conservation populations. Because of the documented 
negative impacts of nonnative trout on cutthroat trout discussed above, 
nonnatives are an ongoing threat to the security of Rio Grande 
cutthroat trout. Additionally, although drought and fire have impacted 
a limited number of populations since the last status review, negative 
impacts from these two factors may increase in response to climate 
change (as discussed in the ``Climate Change'' section below). Based on 
the best scientific and commercial information available to us, we 
conclude that the present or threatened destruction, modification, or 
curtailment of its habitat or range is a threat to the continued 
existence of Rio Grande cutthroat trout.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    No commercial harvest occurs for Rio Grande cutthroat trout. 
Recreational angling occurs on approximately 84 percent of the 
populations (Alves et al. 2007, p. 49). Fishing regulations in New 
Mexico and Colorado appropriately manage recreational angling. For 
example, many of the streams with Rio Grande cutthroat trout are 
``catch and release.'' Those that are not have a 2 (New Mexico) or 4 
(Colorado) fish limit. Many of the streams with pure populations of Rio 
Grande cutthroat trout are remote and angling pressure is light. For 
these reasons, angling is not considered a threat to Rio Grande 
cutthroat trout.
    Scientific collection of Rio Grande cutthroat trout for scientific 
or educational purposes is controlled by a strict permitting process 
that prevents excessive sampling. In addition, advancements in 
molecular technology have resulted in the need for only a small 
clipping from a fin to provide sufficient material to perform molecular

[[Page 27911]]

analysis of genetic purity. To test for whirling disease (see 
``Disease'' section below for further discussion), usually 60 fish are 
collected and sacrificed. However, to minimize the collection of Rio 
Grande cutthroat trout during whirling disease testing, nonnative trout 
are collected preferentially over Rio Grande cutthroat trout, or sample 
sites are selected below a barrier that protects a population of Rio 
Grande cutthroat trout from nonnative trout. In some situations fewer 
than 60 Rio Grande cutthroat trout will be collected and sacrificed for 
testing. For these reasons, overutilization for scientific purposes is 
not considered a threat to Rio Grande cutthroat trout.

Summary of Factor B

    Because no commercial harvest occurs for Rio Grande cutthroat 
trout, fishing regulations in New Mexico and Colorado minimize the 
impact of recreational angling, and scientific collection of Rio Grande 
cutthroat trout for scientific or educational purposes is controlled by 
a strict permitting process that prevents excessive sampling, we 
conclude that the best scientific and commercial information available 
to us indicates that Rio Grande cutthroat trout is not threatened by 
overutilization for commercial, recreational, scientific, or 
educational purposes.

C. Disease or Predation

Disease

    Whirling disease is of great concern to fishery managers in western 
States. Whirling disease is caused by the nonnative myxosporean 
parasite, Myxobolus cerebralis. This parasite was introduced to the 
United States from Europe in the 1950s and requires two separate hosts, 
a salmonid fish and an aquatic worm (Tubifex tubifex) to complete its 
life cycle. Spores of the parasite are released from infected fish when 
they die. The spores are ingested by T. tubifix where they undergo 
transformation in the gut to produce actinosporean triactionomyxons 
(TAMs). Trout are infected either by eating the worms (and TAMs) or 
through contact with water in which TAMs are present.
    The myxosporean parasite became widely distributed in Colorado in 
the early 1990s through the stocking of millions of catchable size 
trout from infected hatcheries (Nehring 2007, p. 1). Up to 2001, it was 
estimated that whirling disease infection had negatively impacted 
recruitment of wild rainbow and brook trout fry (small recently emerged 
fish) in 560-600 km (350-400 mi) of stream in Colorado (Nehring 2007, 
p. 2). In 2006, the number of sites that tested positive for whirling 
disease was considerably higher than in any of the previous field 
seasons (Nehring 2007, p. 11). Whirling disease is also present in 
several streams in New Mexico (67 FR 39943, Patten and Sloane 2007, p. 
11). Laboratory (DuBey et al. 2007, pp. 1411, 1412) and field (Thompson 
1999, pp. 323-325) experiments have shown that Rio Grande cutthroat 
trout is very susceptible to whirling disease.
    Among the four lineages (I, III, V, and VI) of T. tubifix known to 
occur in Colorado, New Mexico, and other states, lineage III is the 
only one susceptible to infection by M. cerebralis (DuBey and Caldwell 
2004, p. 183; Nehring 2007, p. 11). Because T. tubifix is typically 
found in degraded habitat with higher levels of sediment and warmer 
temperatures, it had been hypothesized that Rio Grande cutthroat trout 
were provided some level of protection because they occur in high-
elevation cold-water streams (67 FR 39943). Extensive sampling of 
tubificid worms in Colorado does not support this hypothesis. Nehring 
(2007) collected tubificid worm samples from over 100 sites in 
Colorado, including streams occupied by Rio Grande cutthroat trout. He 
stratified his results by 305 m (1,000 ft) elevation groups from 1829 m 
(6,000 ft) to 3657 m (12,000 ft) (e.g. 1829-2134 m (6,000-7000 ft), 
2134-2438 m (7001-8,000 ft), etc.). Lineage III worms had the greatest 
abundance, outnumbering all of the other lineages combined, at all 
elevations. The number of sites with lineage III worms was 
approximately the same at all elevations from the 1829-2134 m (6,000-
7,000 ft) band up to the 3048-3353 m (10,000-11,000 ft) band (Nehring 
2007, p. 10) indicating that the high-elevation cold-water streams do 
not provide protection from lineage III worms.
    One hundred and five conservation populations (88 percent) are 
judged to have very limited risk from whirling disease or other 
potential diseases because the pathogens are not known to exist in the 
watershed or a barrier blocks upstream fish movement (Alves et al. 
2007, p. 38). Six populations are at minimal risk because they are 
greater than 10 km (6.2 mi) from the pathogen or they are protected by 
a barrier, but the barrier may be at risk of failure (Alves et al. 
2007, p. 38). Eight populations were identified as being at moderate 
risk because whirling disease had been identified within 10 km of 
occupied habitat (Alves et al. 2007, p. 38). In 2006, it was discovered 
that whirling disease had infected brook trout and Rio Grande cutthroat 
trout in Placer Creek, Colorado, a conservation population, and in 2007 
it was chemically treated to remove infected fish and nonnative brook 
trout.
    In 2002, the Pecos, Cebolla, San Juan, Cimarron, Red, and Canones 
rivers in New Mexico were listed as being infected with whirling 
disease (67 FR 39943). By 2007, more than 80 streams and lakes had been 
tested for the disease (Patten and Sloane 2007, pp. 10-13). North 
Bonito Creek, Brazos River, and Los Pinos River were added to the list 
of streams testing positive for whirling disease. Canones and Jacks 
creeks, which had tested positive in 2000, tested negative in 2005, and 
2003, respectively (Patten and Sloane 2007, pp. 10-13). Of the streams 
listed, Rio Cebolla, Pecos River and Cimarron River are occupied by Rio 
Grande cutthroat trout upstream above barriers.
    NMDGF policies and regulations prohibit the stocking of any 
whirling disease positive fish in the State of New Mexico (Patten and 
Sloane 2007, p. 10). All private facilities must maintain a pathogen-
free certification. The Seven Springs Hatchery, which is used for Rio 
Grande cutthroat trout broodstock, has tested negative on all occasions 
since it was refurbished (Patten and Sloane 2007, p. 10). In Colorado 
stocking of whirling disease positive fish in protected habitats, which 
include native cutthroat trout waters, is prohibited (Japhet et al. 
2007, p. 12). Colorado and New Mexico have web sites, brochures, and 
information in their fishing regulations regarding whirling disease and 
what anglers can do to prevent its spread. In addition, both States 
have regulations regarding the stocking of fish by private landowners 
that are designed to eliminate the importation of whirling disease 
positive fish. It states clearly in the fishing regulations that it is 
illegal to stock fish in public waters without prior permission from a 
State agency.
    Whirling disease remains a concern for Rio Grande cutthroat trout 
populations. One Rio Grande cutthroat trout conservation population was 
infected in Colorado, and restoration efforts were immediately 
implemented to address the issue. Although widespread increases in M. 
cerebralis have not been seen, additional infected sites have been 
documented. Because of the limited level of infection currently, 
whirling disease is not seen as a significant threat to populations 
range-wide. However, climate change and warmer stream temperature may 
facilitate the spread of whirling disease in the future (discussed in 
the ``Disease'' section in Factor E below).

[[Page 27912]]

Predation

    Brown trout are piscivores and are the most likely predator on Rio 
Grande cutthroat trout. Additionally, brown trout have been found to 
have a significant negative impact on the condition of coexisting Rio 
Grande cutthroat trout through harassment (e.g., chasing) (Shemai 2004, 
pp. 315-323; McHugh and Budy 2005, p. 2788). It is probable that larger 
brown trout prey on young Rio Grande cutthroat trout and, unchecked, 
brown trout can depress population levels. Warmer water temperatures in 
the future may give brown trout a greater competitive advantage over 
Rio Grande cutthroat trout (discussed in the ``Climate Change'' section 
below). However, we have insufficient information at this time to 
conclude that predation by brown trout is currently a significant 
threat to Rio Grande cutthroat trout.

Summary of Factor C

    One population of Rio Grande cutthroat trout has been infected with 
whirling disease since our 2002 status review and eight conservation 
populations are considered to be at moderate risk of infection. 
Although whirling disease is currently limited in distribution and 
effect, it has the potential to become a more widespread problem due to 
warmer waters that could result from climate change (discussed in the 
``Climate Change'' section below). We have insufficient information to 
conclude that predation is a significant threat at this time. 
Therefore, we conclude that the best scientific and commercial 
information available to us indicates that, although the status of Rio 
Grande cutthroat trout has not yet been affected by disease, Rio Grande 
cutthroat trout is likely to be threatened by disease in the 
foreseeable future.

D. The Inadequacy of Existing Regulatory Mechanisms

    The NMDGF and the CDOW have authority and responsibility for the 
management of Rio Grande cutthroat trout. Rio Grande cutthroat trout is 
designated as a species of special concern by the State of Colorado and 
of special management concern by the State of New Mexcio. The agencies' 
capabilities include the regulation of fishing, law enforcement, 
research, and conservation and educational activities relating to Rio 
Grande cutthroat trout. Policies regarding the stocking of nonnative 
fish (no nonnatives are stocked in Rio Grande cutthroat trout 
populations), minimization of exposure to whirling disease and other 
diseases, and broodstock management are in place in both States. In 
2004, the ``Conservation Plan for Rio Grande Cutthroat trout in 
Colorado'' was approved by the Director of CDOW. The goal of the plan 
is to assure the long-term persistence of Rio Grande cutthroat trout 
throughout its historic range by preserving genetic integrity, reducing 
population fragmentation, and providing suitable habitat to support 
self-sustaining populations (Japhet et al. 2007, p. ii). New Mexico 
(2002) has an approved management plan currently being implemented that 
will ``facilitate long range cooperative, interagency conservation of 
Rio Grande cutthroat trout.''
    Rio Grande cutthroat trout populations have been lost because of 
stream drying (Japhet et al. 2007 pp. 42-44), and other trout 
populations in the Southwest have been extirpated as the result of ash 
flows following fire (Brown et al. 2001 p. 142). Imperiled fish 
populations can be rescued from streams (Brooks 2004, pp. 1-15; Japhet 
et al. 2007, p. 20). In the face of widespread drought or fire 
(discussed in the ``Climate Change'' section below) it is expected that 
many streams would be affected at one time, as seen in the 2002 drought 
(Japhet et al. 2007, pp. 42-44; Patten et al. 2007, pp. 14-40). An 
emergency rescue and evacuation plan is not in place for Rio Grande 
cutthroat trout, nor do we anticipate that this strategy would be 
effective in eliminating the threat of stream drying or post-fire ash 
flows in the face of widespread drought.
    In 2003, a range-wide conservation agreement was signed by CDOW, 
NMDGF, USFS, the Service, BLM, NPS, and Jicarilla Apache Nation. The 
purpose of the agreement is to facilitate cooperation and coordination 
among State, Federal, and tribal agencies in the conservation of Rio 
Grande cutthroat trout. The Conservation Team has met several times and 
the ``Range-wide Status of Rio Grande Cutthroat Trout (Oncorhynchus 
clarki virginalis): 2007'' is a product of the team's cooperative 
effort.

Regulatory Mechanisms Involving Land Management

    Numerous State and Federal laws and regulations help to minimize 
adverse effects of land management activities on Rio Grande cutthroat 
trout. Federal laws that protect Rio Grande cutthroat trout and their 
habitats include the Clean Water Act (33 U.S.C. 1251 et seq.), Federal 
Land Policy and Management Act (43 U.S.C. 1701 et seq.), National 
Forest Management Act (16 U.S.C. 1600 et seq.), Wild and Scenic Rivers 
Act (16 U.S.C. 1271 et seq.), Wilderness Act (16 U.S.C. 1131 et seq.), 
and the National Environmental Policy Act (42 U.S.C. 4321 et seq.). 
Approximately 59 percent of Rio Grande cutthroat trout habitat occurs 
on lands managed by Federal agencies. The majority of those lands are 
managed by the USFS. Rio Grande cutthroat trout occur over a large 
geographic area within the Rio Grande, Santa Fe, and Carson National 
Forests in Colorado and New Mexico. Rio Grande cutthroat trout is 
designated as a sensitive species on all USFS lands.
    The Regional Forester's Sensitive Species List policy is applied to 
projects implemented under the 1982 National Forest Management Act 
Planning Rule. However, in 2005, USFS implemented a new planning rule 
(70 FR 1023, January 5, 2005), which directs land management plans to 
be more strategic and less prescriptive. Under the new rule, land 
management plans identify ecosystem-level desired conditions and 
provide management objectives and guidelines to move toward the desired 
conditions. The land management plans also will provide species-
specific direction for special status species when the broader 
ecosystem-level desired conditions do not provide for their needs. 
However, the United States District Court in Citizens for Better 
Forestry et al. v. U.S. Department of Agriculture (N.D. Calif.) 
enjoined the Forest Service from implementation and utilization of the 
National Forest land management planning rule published on January 5, 
2005 (70 FR 1023). Currently, the U.S. Department of Agriculture Office 
of General Counsel is reviewing this matter and will provide legal 
advice to USFS on how to proceed with forest planning. Therefore, 
efforts specific to forest planning are postponed until further 
direction is available (USFS 2008).
    Threats to depletion of stream flow can be reduced by the U.S. 
Forest Service utilizing its authorities, if any, to further secure 
additional instream flows in Colorado. Rio Grande cutthroat trout 
conservation populations are protected by State instream flow water 
rights or USFS Reserve water rights along 620 km (385 mi) in 63 stream 
segments (approximately 70 percent of occupied habitat) within the Rio 
Grande basin in Colorado. Most of the remaining Rio Grande cutthroat 
trout conservation populations that are not associated with instream 
flow water rights are found on private property within the boundaries 
of the old Spanish Land Grants where natural resource stewardship is 
practiced. Regulatory controls of water quality in Colorado are 
implemented by the

[[Page 27913]]

Colorado Water Quality Control Division and Commission. Water quality 
standards are in place to protect the maintenance of aquatic life in 
coldwater environments, and special resource restrictions are also 
available to provide further site-specific protection to water quality 
(Japhet et al. 2007, p. 18).

Summary of Factor D

    The NMDGFG, CDOW and USFS are actively managing Rio Grande 
cutthroat trout and its habitat. They also have authority for and are 
undertaking fisheries management, research, educational and law 
enforcement activities designed to improve the conservation status of 
the species. There is a range-wide conservation agreement that also 
involves the Service and other parties. Existing regulations, 
authorities, and policies address current threats to the species that 
are subject to regulatory control. However, climate change will have 
potential impact throughout the range of this species. At this time it 
is difficult to state how these effects will be addressed through 
existing regulatory mechanisms.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Climate Change

    In this section, we discuss the aspects of climate change that will 
most likely affect the habitat of Rio Grande cutthroat trout. We begin 
by presenting the evidence that indicates that climate change is 
occurring globally. We then discuss literature related to climate 
change that has been published for the Southwest and southern Rocky 
Mountains that documents changes either that have already occurred or 
that researchers predict will occur. Finally, we present data that have 
been collected for streams occupied by Rio Grande cutthroat trout that 
indicate that the effects of climate change could exacerbate the 
threats discussed above.
    The Intergovernmental Panel on Climate Change (IPCC) is a 
scientific body set up by the World Meteorological Organization and the 
United Nations Environment Program in 1988. It was established because 
policymakers needed an objective source of information about the causes 
of climate change, its potential environmental and socio-economic 
consequences, and the adaptation and mitigation options to respond to 
it. The Service considers the IPCC an impartial and legitimate source 
of information on climate change. In 2007, the IPCC published its 
Fourth Assessment Report, which is considered the most comprehensive 
compendium of information on actual and projected global climate change 
currently available.
    Although the extent of warming likely to occur is not known with 
certainty at this time, the IPCC (2007a, p. 5) has concluded that 
warming of the climate is unequivocal and continued greenhouse gas 
emissions at or above current rates would cause further warming (IPCC 
2007a, p. 13). The IPCC also projects that there will very likely be an 
increase in the frequency of hot extremes, heat waves, and heavy 
precipitation (IPCC 2007a, p. 15). Warming in the Southwest is expected 
to be greatest in the summer (IPCC 2007b, p. 887). Annual mean 
precipitation is likely to decrease in the Southwest and the length of 
snow season and snow depth are very likely to decrease (IPCC 2007b, p. 
887). Most models project a widespread decrease in snow depth in the 
Rocky Mountains and earlier snowmelt (IPCC 2007b, p. 891).
    In consultation with leading scientists from the Southwest, the New 
Mexico Office of the State Engineer prepared a report for the Governor 
(State of New Mexico 2006) which made the following observations about 
the impact of climate change in New Mexico:
    (1) Warming trends in the American Southwest exceed global averages 
by about percent (p. 5);
    (2) Models suggest that even moderate increases in precipitation 
would not offset the negative impacts to the water supply caused by 
increased temperature (p. 5);
    (3) Temperature increases in the Southwest are predicted to 
continue to be greater than the global average (p. 5);
    (4) There will be a delay in the arrival of snow and acceleration 
of spring snow melt, leading to a rapid and earlier seasonal runoff (p. 
6); and
    (5) The intensity, frequency, and duration of drought may increase 
(p. 7).

By the late 21st century, one simulation predicts no sustained snowpack 
south of Santa Fe or in the Sangre de Cristo Mountains (State of New 
Mexico 2006, p. 13). Snow pack would remain in far northern New Mexico 
and southern Colorado but would be greatly reduced in mass, with a 
decrease in water mass between one-third and one-half (State of New 
Mexico 2006, p. 14).
    Consistent with the outlook presented for New Mexico, Hoerling 
(2007, p. 35) states that, relative to 1990-2005, simulations indicate 
that a 25 percent decline in stream flow will occur from 2006-2030 and 
a 45 percent decline will occur from 2035-2060 in the Southwest. Seager 
et al. (2007, p. 1181) show that there is a broad consensus among 
climate models that the Southwest will get drier in the 21st century 
and that the transition to a more arid climate is already under way. 
Only one of 19 models has a trend toward a wetter climate in the 
Southwest (Seager et al. 2007, p. 1181). Stewart et al. (2004, p. 1152) 
show that timing of spring streamflow in the western United States 
during the last five decades has shifted so that the major peak now 
arrives 1 to 4 weeks earlier, resulting in less flow in the spring and 
summer. They conclude that almost everywhere in North America, a 10 to 
50 percent decrease in spring-summer streamflow fractions will 
accentuate the seasonal summer dry period with important consequences 
for warm-season water supplies, ecosystems, and wildfire risks (Stewart 
et al. 2004, p. 1154). An increase in average mean air temperature of 
just over 1 [deg]C (2.5 [deg]F) in Arizona and just under 1 [deg]C (1.8 
[deg]F) in New Mexico since 1976 has already been documented (Lenart 
2007, p. 4). Udall (2007, p. 7) found that multiple independent data 
sets confirm widespread warming in the West. Long-term studies (25 plus 
years) of Mexican jays (Aphelocoma ultramarina) in Arizona and of 
yellow-bellied marmots (Marmota flaviventris) in the Rocky Mountains 
indicate changes in the timing of important life history events (e.g., 
breeding, emergence from hibernation) for both species related to 
warmer temperatures (Parmesan and Galbraith 2004, pp. 18, 19).
    As we will discuss below, climate change is predicted to have four 
major effects on the cold water habitat occupied by Rio Grande 
cutthroat trout: (1) Increased water temperature; (2) decreased stream 
flow; (3) a change in the hydrograph (a graphical representation of the 
distribution of water discharge or runoff over a period of time); and 
(4) an increased occurrence of extreme events (fire, drought, and 
floods).

Increased Water Temperature

    Water temperature influences the survival of salmonids in all 
stages of their life cycle. Alterations in the temperature regime from 
natural background conditions negatively affect population viability, 
when considered at the scale of the watershed or individual stream 
(McCullough 1999, p. 160). Salmonids are classified as coldwater fish 
with thermal preferences centered around 15 [deg]C (59 [deg]F) (Shuter 
and Meisner 1992, p. 8). High temperatures suppress appetite and 
growth, can influence behavioral interactions with other fish (Shrank 
et al. 2003, p. 100), or can be lethal

[[Page 27914]]

(McCullough 1999, p. 156). Salmonids inhabiting warm stream segments 
have higher probabilities of dying from stress (McCullough 1999, p. 
156).
    Eaton and Scheller (1996, p. 1111) state that the maximum 
temperature tolerance for cutthroat trout is 23.3 [deg]C (74 [deg]F), 
but Dunham et al. (2003b, p. 1042) state that Lahontan cutthroat trout 
(Oncorhynchus clarki henshawi) show signs of stress (decreased growth 
and appetite and increased mortality) when water temperature exceeds 22 
[deg]C (71.6 [deg]F) for even a short time (less than 1 day). For 
Bonneville cutthroat trout, the 7-day upper incipient lethal 
temperature (temperature lethal to 50 percent of the fish) was 24.2 
[deg]C (75.6 [deg]F) under constant thermal conditions (Johnstone and 
Rahel 2003, p. 96). However, when the temperature was cycled daily 
between 16-26 [deg]C (60.8-78.8 [deg]F) for 7 days, similar to what the 
trout would experience in high mountain streams, all trout survived 
(Johnstone and Rahel 2003, p. 97). Dickerson and Vineyard (1999, pp. 
519, 520) found a similar result (cycling between 20 and 26 [deg]C (68 
and 78.8 [deg]F)) for Lahontan cutthroat trout. Although trout may 
survive cyclic exposures to high temperatures, growth is slowed or 
stopped due to the high metabolic costs and reduced food intake 
(Dickerson and Vineyard 1999, p. 519; Johnstone and Rahel 2003, p. 98).
    Although temperature preferences of Rio Grande cutthroat trout have 
not been researched specifically, their optimum growth temperature 
(appetite is high and maintenance requirements low) is most likely in 
the range of 13-15 [deg]C (55.4-59 [deg]F), similar to other cutthroat 
trout (Meeuwig et al. 2004, p. 213; Bear et al. 2007, p. 1118) and 
their upper incipient lethal limit is most likely near 23-24 [deg]C 
(73.4-75.2 [deg]F), as has been found for other subspecies of cutthroat 
trout (Wagner et al. 2001, p. 434; Johnstone and Rahel 2003, p. 97). 
Upper incipient lethal limit (temperature at which 50 percent of the 
fish can survive for 7 days) for rainbow trout ranges from 24-26 [deg]C 
(75.2-78.8 [deg]F), for brown trout 23-26 [deg]C (73.4-78.8 [deg]F), 
and for brook trout 24-25 [deg]C (75.2-77 [deg]F) (McCullough 1999, pp. 
47, 48), which means these nonnative trout are better able to tolerate 
higher water temperatures than cutthroat trout.
    The IPCC states that of all ecosystems, freshwater ecosystems will 
have the highest proportion of species threatened with extinction due 
to climate change (Kundzewicz et al. 2007, p. 192). Species with narrow 
temperature tolerances will likely experience the greatest effects from 
climate change, and it is anticipated that populations located at the 
margins of species' hydrologic and geographic distributions will be 
affected first (Meisner 1990a, p. 282). Climate change has already had 
or is predicted to have negative consequences on coldwater fisheries 
globally (Nakano et al. 1996, p. 711; Hari et al. 2006, p. 24), across 
North America (Meisner 1990a, pp. 287, 290; Regier and Meisner 1990, p. 
11; Carpenter et al. 1992, p. 124; Eaton and Scheller 1996, p. 1111; 
O'Neal 2002, p. 3; Poff et al. 2002, p. iv; Chu et al. 2005, p. 303; 
Preston 2006, pp. 106, 107, 110, 111, 115; Reiman et al. 2007, pp. 
1553, 1558), and in the Southwest and Rocky Mountains specifically 
(Keleher and Rahel 1996, p. 1; Rahel et al. 1996, pp. 1116, 1122; 
O'Neal 2002, pp. 43, 44; Preston 2006, pp. 101, 102, 113) through 
increases in ground and surface water temperature.
    The magnitude of habitat loss due to increased water temperature 
depends on the climate change model used, the model used to predict the 
air temperature/water temperature relationship, and the timeframe. 
Keleher and Rahel (1996, p. 4) found that the distribution of salmonids 
in Wyoming streams was limited to areas where mean July air temperature 
did not exceed 22 [deg]C (71.6 [deg]F). They projected that for 
temperature increases of 1, 2, 3, 4, or 5 [deg]C, there would be a 
corresponding loss of area suitable for salmonids of 16.2, 29.1, 38.5, 
53.3, and 68.0 percent, respectively (Keleher and Rahel 1996, p. 4). 
Rahel et al. (1996) used three approaches to examine potential salmonid 
habitat loss due to warming in the North Platte river drainage of the 
Rocky Mountains. They found that there was a loss of 9 to 76 percent of 
coldwater habitat based on air temperature increases of 1 to 5 [deg]C 
(Rahel et al. 1996, p. 1120). Other studies have predicted losses of 
18-92 percent of suitable natal bull trout (Salvelinus confluentus) 
habitat (Rieman et al. 2007, p. 1558), and Preston (2006, p. 92), in a 
re-analysis of other studies, found a 20, 35, and 50 percent loss of 
coldwater habitat from the Rocky Mountains in 2025, 2050, and 2100, 
respectively.
    In these studies, habitat loss occurs in the lower elevation stream 
reaches (or lower latitude streams) due to increased temperatures. As a 
result, salmonid populations will be restricted to increasingly higher 
elevations or to more northern latitudes (Meisner et al. 1988, p. 6; 
Regier and Meisner 1990, p. 11; Keleher and Rahel 1996, p. 2; Nakano et 
al. 1996, pp. 716, 717; Rahel et al. 1996, p. 1122; Poff et al. 2002, 
p. 7; Rieman et al. 2007, p. 1558). Consequently, coldwater species 
occupying the southern distributions of their range are seen as more 
susceptible to extirpation as a consequence of global climate change 
(Poff et al. 2002, p. 8; Rieman et al. 2007, pp. 1552, 1553). Rio 
Grande cutthroat trout are the southernmost subspecies of cutthroat 
trout (Behnke 2002, p. 143).
    Rio Grande cutthroat trout primarily occupy high-elevation 
headwater tributaries. Dispersal to new habitats is unlikely because 
they currently occupy the uppermost available habitat. Warming of lower 
elevation stream segments may limit restoration opportunities in the 
future and provide a competitive advantage to brown, rainbow, and brook 
trout in locations where these nonnatives occur with Rio Grande 
cutthroat trout (De Staso and Rahel 1994, pp. 293, 294; Dunham et al. 
2002, p. 380; Paroz 2005, p. vi; Bear et al. 2007, p. 1118; Shemai et 
al. 2007, p. 322).
    The Santa Fe and Carson National Forests have monitored stream 
temperature data using thermographs (instruments that record 
temperature at designated intervals, e.g., once every 4 hours) (Eddy 
2005, Martinez 2007). From 2001-2003, 47 thermograph stations were used 
to monitor 21 streams on the Santa Fe National Forest, representing 385 
km (239 mi) of stream (Eddy 2005, p. 5). Seven of the 21 streams are 
currently occupied by Rio Grande cutthroat trout conservation 
populations; all 21 are believed to be historical habitat. Temperature 
data collected were compared with New Mexico Environment Department 
(NMED) standards for high quality coldwater fisheries and with Santa Fe 
National Forest standards, which are slightly more stringent than NMED 
but are more in line with standards for coldwater fisheries in the 
western States (Table 3) (Eddy 2005, p. 4). ``Properly functioning'' 
indicates that the water temperature of the stream is within the 
optimal range for feeding, physiology, and behavior for coldwater fish. 
``At risk'' indicates that the water temperature is slightly warmer 
than optimal, and ``not properly functioning'' indicates that the water 
temperature is too warm to support a healthy coldwater fishery.

[[Page 27915]]



                                   Table 3.--Santa Fe National Forest and NMED
                   [Water quality temperature standards for high quality coldwater fisheries]
----------------------------------------------------------------------------------------------------------------
 Water temperature standards     Properly functioning               At risk            Not properly  functioning
----------------------------------------------------------------------------------------------------------------
Santa Fe National Forest 7-   <=64 [deg]F (<=17.8         64 to 70 [deg]F...........  >70 [deg]F (>21.1 [deg]C).
 Day Average Maximum.          [deg]C).                   (17.8-21.1 [deg]C)........
NMED 3-Day Average Maximum..  <68 [deg]F (<20 [deg]C)...  68 to <73.4 [deg]F........  >=73.4 [deg]F (23 [deg]C).
                                                          (20 to <23 [deg]C)........
----------------------------------------------------------------------------------------------------------------

    Using the Santa Fe National Forest standards, stream segments 
represented by 12 thermograph stations were properly functioning (67.3 
km (41.8 mi)), stream segments represented by 20 stations were at risk 
(162.1 km (100.7 mi)), and stream segments represented by 15 stations 
were not properly functioning (154.7 km (96.1 mi)) (Eddy 2005, p. 5). 
Using NMED standards, stream segments represented by 23 stations (172.7 
km (107.3 mi)) were properly functioning, stream segments represented 
by 12 stations (82.2 km (51.1 mi)) were at risk, and stream segments 
represented by 12 stations (129.1 km (80.2 mi)) were not properly 
functioning (Eddy 2005, p. 5). Only nine streams were properly 
functioning for their entire length, using both standards. Of these, 
only one is occupied by a Rio Grande cutthroat trout conservation 
population (Cave Creek) (Eddy 2005, p. 5). The Pecos River and Rio de 
las Vacas are properly functioning in occupied Rio Grande cutthroat 
trout habitat but have at risk (Pecos River) or not properly 
functioning sections (Rio de las Vacas) below occupied habitat (Eddy 
2005, pp. 34, 35, 92). Canones, Polvadera, and Rio Cebolla were the 
other streams monitored that have conservation populations of Rio 
Grande cutthroat trout. These streams were identified as at risk or not 
properly functioning (Rio Cebolla) in occupied habitat (Eddy 2005, pp. 
9, 19, 26).
    Monitoring on the Carson National Forest indicated that Comanche 
Creek had several periods in which temperature standards were exceeded 
(Martinez 2007, pp. 3-22). Eight sites on Comanche Creek were monitored 
in 1998, 1999, and 2004. Temperatures were highest in 1998 and 1999, 
years of lower runoff. Temperatures in 1998 were very high, with 5 of 
the 8 sites recording temperatures from 26.6-29.5 [deg]C (80-85 [deg]F) 
(Martinez 2007, pp. 3-22). At the remaining three sites, temperatures 
reached 26.4 [deg]C (79.5 [deg]F). Thermographs went in on June 23 each 
year, and in 1998, maximum temperatures ranged from 22.9-24 [deg]C 
(73.2-76 [deg]F) at all eight sites on the first day the recorders were 
deployed, indicating that there were probably several days of warm 
temperatures that occurred before monitoring began (Martinez 2007, pp. 
3-22). In total, of 14 streams occupied by Rio Grande cutthroat trout 
and monitored by thermographs on the Santa Fe and Carson National 
Forests, 8 streams were either at risk or not properly functioning 
because of high water temperature (NMED 2007, pp. 15-331; Eddy 2005, 
pp. 8-116; Martinez 2007, pp. 3-22). An additional conservation 
population in Colorado was also identified at risk from high water 
temperatures by Pritchard and Cowley (2006, p. 39). Because only a 
fraction of the streams occupied by Rio Grande cutthroat trout have 
been monitored, there are likely more that are at risk.
    The thermograph data collected on the Santa Fe and Carson National 
Forests indicate that stream temperatures in several streams are 
already at risk or are considered ``not properly functioning'' for 
trout. Because air temperature and consequently water temperature are 
expected to increase with climate change, we would anticipate that more 
streams that are currently not properly functioning will become 
unsuitable for Rio Grande cutthroat trout, those currently at risk will 
enter the not properly functioning category, and more streams will fall 
into the at risk category for temperature. As a consequence, suitable 
habitat will decrease and fragmentation will increase.
    In contrast to the potential negative impacts of water temperature 
increase on Rio Grande cutthroat trout, there could also be a potential 
benefit. Cold summer water temperatures (mean July temperature of less 
than 7.8 [deg]C (46 [deg]F)) have been found as a limiting factor to 
recruitment of cutthroat trout in high-elevation streams (Harig and 
Fausch 2002, p. 545; Coleman and Fausch 2007, pp. 1238-1240). Coleman 
and Fausch (2007, p. 1240) found that cold summer water temperatures in 
Colorado streams likely limited recruitment of cutthroat trout because 
of reduced survival of age-0 fish (fish less than 1 year old). Harig 
and Fausch (2002, p. 538) recorded summer water temperatures in 5 
streams in New Mexico and 11 streams in Colorado from 1996 to 1999 
(Harig and Fausch 2002, p. 540). None of the streams in New Mexico had 
July water temperatures below 7.8 [deg]C (46 [deg]F) (lowest July 
average was in the Pecos River, 9.2 [deg]C (48.6 [deg]F)). Three of 
four streams in Colorado that no longer had translocated fish present 
had summer averages below 7.8 [deg]C (46 [deg]F) (Harig and Fausch 
2002, pp. 538, 539). The remaining 8 streams in Colorado had summer 
averages >=8.3 [deg]C (46.9 [deg]F), indicating that cold summer water 
temperatures were most likely not limiting for these Rio Grande 
cutthroat trout populations (Harig and Fausch 2002, pp. 538, 539). Two 
of the four streams (Little Medano and Unknown Creek), which no longer 
had transplanted fish at the time of Harig and Fausch's research (1996-
1998), dried in 2002 (Alves et al. 2007, pp. 43, 44), raising the 
possibility that insufficient refugial habitat may have been limiting, 
not low summer water temperatures.
    Cold summer water temperatures have been identified as limiting in 
one stream: Deep Canyon, Colorado (Pritchard and Cowley 2006, p. 42). 
However, Alves et al. (2007 database) indicate that Deep Canyon has 
temperatures from 8 to 16 [deg]C (46.4 to 60.8 [deg]F) during spawning 
and incubation periods. Of the 14 Rio Grande cutthroat trout streams 
monitored with thermographs on the Santa Fe and Carson National 
Forests, two (Pecos and Mora rivers) were found to have July 
temperatures less than 7.8 [deg]C (46 [deg]F) (data summarized from 
Eddy 2005, Martinez 2007). The result for the Pecos River contrasts 
with the data Harig and Fausch (2002, p. 540) collected (9.2 [deg]C 
(48.6 [deg]F)) and likely reflects a difference in thermograph 
placement or year (e.g., temperature variability, amount of runoff).
    In summary, we find that data collected thus far indicate that warm 
water temperatures have already reached the likely limits of 
suitability in some Rio Grande cutthroat trout streams and several 
others are at risk. Water temperatures are expected to increase in the 
future, affecting more streams and making lower elevation reaches 
either

[[Page 27916]]

marginal or unsuitable. This is particularly true for populations that 
are located in New Mexico and are at the southernmost extent of the 
range but could also be true for smaller streams in Colorado. Although 
cold water temperatures are limiting to some high-elevation salmonid 
populations, cold water limitation has not been convincingly 
demonstrated for any Rio Grande cutthroat trout population. Therefore, 
we view the negative impact of stream warming to outweigh any benefit 
that may occur from increased water temperature.
    The studies cited above that forecast coldwater habitat loss, 
calculate the loss of habitat based on increases in temperature alone, 
assuming temperatures will rise above the thermal tolerance limits of 
coldwater species, thereby limiting the amount of suitable habitat 
available. The ancillary effects of increased temperature, such as 
increased habitat fragmentation (Rahel et al. 1996, pp. 1121, 1122; 
Rieman et al. 2007, pp. 1553, 1560, 1562), changes in invertebrate prey 
base (both species composition and availability) (Ries and Perry 1995, 
p. 204; O'Neal 2002, p. 4; IPCC 2002, p. 17; Harper and Peckarsky 2006, 
p. 618; Bradshaw and Holazpel 2008, p. 157), effects on spawning (Jager 
et al. 1999, p. 236), increased competitive interactions with nonnative 
trout (Meisner 1990b, p. 1068; De Staso and Rahel 1994, pp. 289, 294; 
O'Neal 2002, p. 33; Chu et al. 2005, p. 307; Sloat et al. 2005, p. 
235), additional invasive species (IPCC 2002, p. 32), increased 
susceptibility to disease (Hari et al. 2006, p. 24), and effects on 
water quality (e.g., dissolved oxygen, nutrients, pH) (Meisner et al. 
1988, p. 7), are not considered in calculating the potential habitat 
loss.
    Of these factors, increased fragmentation, increased effects from 
nonnative fish, and increased disease risk are considered of particular 
importance to Rio Grande cutthroat trout and are discussed in more 
detail.
    Fragmentation. Climate change is predicted to increase 
fragmentation of coldwater fish habitat (Nakano et al. 1996, p. 719; 
Rahel et al. 1996, p. 1122; Rieman et al. 2007, p. 1553). Currently, 
112 of 120 (93 percent) conservation populations of Rio Grande 
cutthroat trout exist as fragments, with no well-connected populations 
(Alves et al. 2007, p. 29). Only one population has a moderate degree 
of connectivity (Comanche Creek) (2007 database). As noted above, 
Comanche Creek currently has very high water temperatures (Martinez 
2007, pp. 3-22), and several of the small tributaries of upper Comanche 
Creek dried in 2006 (Patten et al. 2007, p. 76). Consequently, the one 
moderately well-connected population may already be at risk. Seven Rio 
Grande cutthroat trout conservation populations are considered weakly 
networked (occupied habitat consists of 2-3 connected streams, possible 
infrequent straying of adults may occur) (Alves et al. 2007, p. 77). Of 
these seven, six have connecting stream segments less than 5 feet in 
width (2007 database), and are therefore considered at risk from 
drying. Consequently, fragmentation of these weakly networked systems 
appears reasonably likely in the foreseeable future.
    Nonnative Fish Interactions. Water temperature is a determining 
factor in the distribution of salmonids (Rahel and Hubert 1991, p. 326; 
Schrank et al. 2003, p. 100; Sloat et al. 2005, p. 225). Additionally, 
temperature regime is a key determinant of the outcome of competitive 
interactions in a fish community (MuCullough 1999, p. 156). Fish living 
within their optimum temperature range have improved performance 
relative to other species not within their optimum range (MuCullough 
1999, p. 156). There is evidence that the reason cutthroat trout occupy 
headwater streams and rainbow, brook, and brown trout occupy downstream 
reaches is because of the influence of temperature on competitive 
abilities (Dunham et al. 2002, p. 380). DeStaso and Rahel (1994, pp. 
293, 294) looked at competition between Colorado River cutthroat trout 
(Oncorhynchus clarki pleuriticus) and brook trout. They found that at 
warmer water temperatures (20 [deg]C (68 [deg]F)) brook trout was 
dominant, as evidenced by a higher level of interspecific aggression, 
more time spent at the optimal feeding position, and greater food 
consumption (DeStaso and Rahel 1994, pp. 293, 294). Brook trout also 
tolerated higher temperatures (DeStaso and Rahel 1994, p. 294).
    As mentioned earlier, when brook trout co-occur with cutthroat 
trout, species interactions act to suppress cutthroat trout populations 
(Dunham et al. 2002, p. 378; Young and Guenther-Gloss 2004, p. 193; 
Peterson et al. 2004, pp. 765-769). Because brook trout tolerate higher 
temperatures, warmer stream temperatures would provide a competitive 
advantage to brook trout over Rio Grande cutthroat trout, exacerbating 
the problems that already exist for Rio Grande cutthroat trout 
populations.
    In New Mexico, brown trout is the most common nonnative trout 
present in Rio Grande cutthroat trout conservation populations 
(summarized from 2007 database). Jager et al. (1999, p. 232) modeled 
the effects of an increase of 2 [deg]C air temperature on brown trout 
distribution in the Sierra Nevada, California. They found that brown 
trout numbers would increase in upstream cooler reaches, and decrease 
downstream through starvation of juvenile and adult fish (Jager et al. 
1999, p. 235). This is consistent with observations in Switzerland. In 
Switzerland in 1987, after a long period of essentially stable river 
water temperatures, water temperatures took an abrupt and significant 
increase to a higher mean level, which was attributed to a 
corresponding increase in air temperature (Hari et al. 2006, pp. 10, 
21). Suitable habitat for brown trout, a trout species native to the 
area, moved upstream, and downstream portions became unsuitable (Hari 
et al. 2006, pp. 10, 21).
    McHugh and Budy (2005, p. 2791) hypothesized that cold incubation 
temperatures might explain why brown trout did not form self-sustaining 
populations at high elevations in Logan River, Utah, where upstream 
water temperatures were not too cold for adult brown trout. Because 
brown trout have a higher optimal growth temperature (between 13-18 
[deg]C) than cutthroat trout (12-13 [deg]C), and because cold 
incubation temperatures may currently be limiting brown trout range 
expansion upstream, it is anticipated that warmer water temperatures 
will make additional upstream habitat suitable for brown trout, 
reducing the area where Rio Grande cutthroat trout are now dominant.
    When cutthroat trout co-occur with rainbow trout, cutthroat trout 
typically occupy the upper colder reaches and rainbow trout occupy the 
lower, warmer stream reaches (Sloat et al. 2005, p. 235; Robinson 2007, 
p. 80). As identified by Alves et al. (2007, p. 35), rainbow trout 
occupy the same stream reaches as four conservation populations of Rio 
Grande cutthroat trout. Rainbow trout have a higher thermal tolerance 
than do cutthroat trout (Bear et al. 2007, pp. 1115, 1116). Because 
rainbow trout are able to tolerate higher temperatures than Rio Grande 
cutthroat trout, we expect that warming stream temperatures will give 
rainbow trout a competitive advantage over Rio Grande cutthroat trout. 
Monitoring and maintenance of barriers will continue to be essential, 
to prevent hybridization and competition.
    White sucker is native to the middle elevations of the Pecos and 
Canadian river drainages in New Mexico, but it has been introduced 
widely throughout the State and is sympatric with at least two 
populations of Rio Grande cutthroat trout (Sublette et al. 1990, p. 
199; 2007

[[Page 27917]]

database). White sucker has a preferred water temperature of 22.4-27.1 
[deg]C (72.3-80.8 [deg]F) (Sublette et al. 1990, p. 198). Sublette et 
al. (1990, p.199) note that white sucker is highly fecund (able to 
reproduce) and often dominates a body of water. Comanche Creek 
(elevation approximately 2900 m (9500 ft)) has an abundant white sucker 
population, most likely due to the warm water temperatures discussed 
above. In 2007, over 20,000 white sucker were removed from Comanche 
Creek during a Rio Grande cutthroat trout restoration project (Patten 
2007). Before the restoration, fish biomass was dominated by white 
sucker, and an inverse relationship was found between Rio Grande 
cutthroat trout density and white sucker density (Patten et al. 2007, 
pp. 17, 18). Because both white sucker and Rio Grande cutthroat trout 
feed on aquatic insects, there is the potential for high numbers of 
white sucker to negatively impact food availability for Rio Grande 
cutthroat trout. We would anticipate the warmer stream temperatures 
would lead to more stream habitat becoming suitable for white sucker 
with potential negative impacts on Rio Grande cutthroat trout 
populations.
    Disease. As mentioned earlier (see the ``Disease and Predation'' 
section in Factor C above) it had been thought that Rio Grande 
cutthroat trout were provided some level of protection against whirling 
disease because tubificid worms are most abundant in warm, degraded 
habitats and Rio Grande cutthroat trout occur in high-elevation, 
coldwater streams (67 FR 39943). However, Nehring (2007, p. 10) found 
equal abundance of lineage III tubificid worms in elevations from 1,829 
m (6,000 ft) to 3,657 m (12,000 ft). Thus, it is clear that elevation 
does not provide protection from exposure to the disease.
    El-Matubouli et al. (1999) found that temperatures from 10-15 
[deg]C (50-59 [deg]F) were optimum for development and maturation of 
the parasite inside the tubificid worm. Blazer et al. (2003, p. 24) 
found that the greatest production of TAMs occurred at temperatures 
from 13-17 [deg]C (55.4-62.6 [deg]F). Although the effect of 
temperature on survival of the tubificid worms was not statistically 
detectable, DuBey et al. (2005, p. 341) found that survival was 
consistently higher at 17 [deg]C (62.6 [deg]F) than at 5 [deg]C (41 
[deg]F). Schisler et al. (2000, p. 862) found that multiple stressors 
on rainbow trout, especially the combination of M. cerebralis infection 
and temperature, increased mortality drastically. At 12.5 [deg]C (54.5 
[deg]F) mean mortality of rainbow trout exposed to M. cerebralis was 
41.7 percent. Mean mortality of rainbow trout exposed to M. cerebralis 
and held at a temperature of 17 [deg]C (62.6 [deg]F) was 60 percent 
(Schisler 2000, p. 861). Water temperature often exceeds 17 [deg]C 
(62.6 [deg]F) in July and August in Rio Grande cutthroat trout streams 
that have been monitored (Eddy 2005, Martinez 2007).
    Thompson et al. (1999, p. 318) found that as water temperature 
increased from May to July, rainbow and cutthroat trout infected with 
M. cerebralis suffered high rates of mortality even though they had 
survived well in the winter. In a field study of the effects of water 
temperature, discharge, substrate size, nutrient concentration, primary 
productivity, and relative abundance of T. tubifix, de la Hoz Franco 
and Budy (2004, p. 1183) found that prevalence of M. cerebralis in 
trout increased with water temperature. Across sites where cutthroat 
trout were present, the lowest prevalence of infection occurred in the 
headwaters where average daily water temperature was 9.2 [deg]C (48.6 
[deg]F), whereas the highest levels of infection occurred at a low 
elevation site where the temperature was the highest (>12 [deg]C (53.6 
[deg]F)) (de la Hoz Franco and Budy 2004, p. 1186).
    While water temperature in some streams may warm to the point (>20 
[deg]C (68 [deg]F)) of inhibiting the production of TAMs (Blazer et al. 
2003, p. 24), it is anticipated that the overall increases in water 
temperature will be favorable for T. tubifix and TAM production. From 
these studies we conclude that elevation does not provide protection to 
Rio Grande cutthroat trout populations and that increasing water 
temperature would increase the production of TAMs and the survival of 
tubificid worms (up to about 20 [deg]C (68 [deg]F)), and increased 
water temperature would increase mortality of infected Rio Grande 
cutthroat trout.
    In summary, stream warming will most likely decrease the amount of 
suitable habitat available for Rio Grande cutthroat trout. Warmer 
stream temperatures may in the foreseeable future make currently 
occupied reaches of stream more stressful or unsuitable. Suitable 
habitat is likely to be reduced, primarily at the downstream end of 
stream reaches and in small tributaries, leading to increased 
fragmentation, shorter occupied segments, and increased risk of 
extirpation. Warmer water temperatures will allow nonnative fishes to 
expand their range and give them a competitive advantage over Rio 
Grande cutthroat trout. Stress from warm water temperatures increases 
susceptibility to and mortality from disease. Although whirling disease 
positive sites are currently still limited within the range of Rio 
Grande cutthroat trout, managers will need to continue to monitor the 
disease closely. Increased water temperatures would increase the threat 
posed by whirling disease.

Decreased Stream Flow

    Current models suggest a decrease in precipitation in the Southwest 
(Seager et al. 2007, p. 1181; Kundzewicz et al. 2007, p. 183), which 
would lead to reduced stream flows and a reduced amount of habitat for 
Rio Grande cutthroat trout. Stream flow is also predicted to decrease 
in the Southwest even if precipitation were to increase moderately 
(Nash and Gleick 1993, p. ix; State of New Mexico 2005, p. 6; Hoerling 
2007, p. 35). Winter and spring warming causes an increased fraction of 
precipitation to fall as rain, resulting in a reduced snow pack, an 
earlier snowmelt, and decreased summer runoff (Christensen et al. 2004, 
p. 4; Stewart et al. 2005, p. 1137; Regonda et al. 2005, p. 373). 
Earlier snowmelt and warmer air temperatures lead to a longer dry 
season, which affects stream flow. Warmer air temperatures lead to 
increased evaporation, increased evapo-transpiration, and decreased 
soil moisture. These three factors would lead to decreased stream flow 
even if precipitation increased moderately.
    The effect of decreased stream flow is that streams become smaller, 
thereby reducing the amount of habitat available for aquatic species 
(Lake 2000, p. 577). A smaller stream is affected more by air 
temperature than a larger one, exacerbating the effects of warm (and 
cold) air temperature (Smith and Lavis 1975, p. 229). Small headwater 
streams, such as those occupied by Rio Grande cutthroat trout, and 
intermittent streams may dry completely. Seventy-one percent of Rio 
Grande cutthroat trout streams are less than 8 km (5 mi) in length 
(Alves et al. 2007, p. 26). Because stream length is one indicator of 
population viability (Harig et al. 2000, p. 997; Hilderbrand and 
Kershner 2000, p. 515; Young et al. 2005, p. 2405; Cowley 2007 10.1002/
aqc.845), further shortening of Rio Grande cutthroat trout streams due 
to drying is expected to have a negative impact on populations.
    In fact, fourteen Rio Grande cutthroat trout streams with 
conservation populations became intermittent, and had populations 
negatively impacted or lost because of the 2002 drought (Japhet et al. 
2007, pp. 42-44; Patten et al. 2007, pp. 14, 31, 32, 34, 39, 76). The 
number of streams impacted was most likely higher, because managers 
only survey a fraction of the 120 conservation populations in any given 
year. Approximately 27 conservation

[[Page 27918]]

populations are in streams that are 1.5 m (5 ft) or less in width 
throughout their entire length (2007 database). An additional 29 stream 
segments that are tributaries to the conservation populations are also 
less than 1.5 m (5 ft) in width (2007 database), which indicates that 
fragmentation of existing connected populations could increase. We 
recognize that not all streams less than 1.5 m (5 ft) wide have an 
equal probability of drying. Some are likely spring fed or are narrow 
and deep, thus decreasing the likelihood of drying. However, because of 
the high number of Rio Grande cutthroat trout streams less than 8 km (5 
mi) in length (71 percent of conservation populations) and less than 
1.5 m (5 ft) wide, the risk of drying is considered high.
    Insight into the effects that climate change may have on headwater 
streams is provided by research done at the Experimental Lakes Area in 
northwestern Ontario (Schindler et al. 1996). The experimental area was 
set up in 1968, and precipitation, evaporation, air temperature, wind 
velocity, and other meteorological and hydrological parameters were 
monitored continuously throughout the 1970 to 1990 study period 
(Schindler et al. 1996, p. 1005). During this period, the area 
experienced gradual air temperature warming (1.6 [deg]C (2.9 [deg]F)) 
and decreased precipitation (as measured by a decline of over 50 
percent in annual runoff) (Schindler et al. 1996, p. 1004). Whether 
these changes can be attributed to climate change or local variation is 
unknown, but they are consistent with changes that are predicted under 
global climate change scenarios. In the early 1970s, two streams in the 
area were perennial and one stream was dry for less than 10 days per 
year. By the late 1980s all three streams were dry for 120-160 days 
during the summer (Schindler et al. 1996, p. 1006). Because northern 
latitude ecosystems mimic higher elevation systems in southern 
latitudes, the effects seen on these streams likely represent what may 
happen at high-elevation streams in New Mexico and Colorado, within the 
range of Rio Grande cutthroat trout.
    In summary, stream drying has already had a negative impact on 
several Rio Grande cutthroat trout populations; 71 percent of Rio 
Grande cutthroat trout conservation populations are in stream fragments 
8 km (5 mi) or less in length, and many of the populations are in 
streams less than 1.5 m (5 ft) wide. Further, the increased risk of 
stream drying as a result of climate change, leading to shorter stream 
segments and increased fragmentation, is seen as high. A rangewide 
emergency rescue and evacuation plan does not exist for Rio Grande 
cutthroat trout and would likely not be effective. If widespread 
drought were to occur, affecting many streams at the same time, it is 
unclear if sufficient facilities or donor streams exist to accept the 
rescued fish, or if the effort would take place according to a 
carefully conceived, well-organized plan.

Change in Hydrograph

    Changes in air temperature and precipitation will likely lead to 
changes in the magnitude, frequency, timing, and duration of runoff 
(Poff et al. 2002, p. 4). Stewart et al. (2004, p. 1152) show that 
spring streamflow during the last five decades has shifted so that the 
major peak now arrives 1 to 4 weeks earlier, resulting in declining 
fractions of flow in the spring and summer. The life history of 
salmonids is closely tied to the flow regime, runoff in particular 
(Fausch et al. 2001, p. 1440). A change in timing or magnitude of 
floods can scour the streambed, destroy eggs, or displace recently 
emerged fry downstream (Erman et al. 1988, p. 2199; Montgomery et al. 
1999, p. 378; Fausch et al. 2001, p. 1440). The environmental cues for 
spawning of Rio Grande cutthroat trout are not known with certainty, 
but they are most likely tied to increasing water temperature, 
increasing day length, and possibly flow, as it has been noted that 
they spawn when runoff from snowmelt has peaked and is beginning to 
decrease (Behnke 2002, p. 141; Pritchard and Cowley 2006, p. 25). 
Consequently, a change in the timing of runoff from spring to winter 
could disrupt spawning cues because peak flow would occur when the days 
are still short in length and water temperatures cold.
    Increased winter temperatures cause more precipitation to fall as 
rain instead of snow (Regonda et al. 2005, p. 373). Snow covering small 
streams provides valuable insulation that protects aquatic life 
(Needham and Jones 1959, p. 470; Gard 1963, p. 197). Gard (1963, p. 
196) measured temperatures above, within, and below the snow at Sagehen 
Creek, California, a small Sierra Nevada mountain stream. He found that 
although there was a 35.4 [deg]C (63.8 [deg]F) diurnal air temperature 
variation, within the snow the temperature variation was only 1.3 
[deg]C (2.3 [deg]F) and the water temperature in the stream below 
varied by only 0.3 [deg]C (0.55 [deg]F). Stream freezing, which is more 
likely absent insulating snow cover, has been suggested as the cause of 
the extirpation of one Rio Grande cutthroat trout population (Ferrell 
2006, p. 11). Anchor ice (ice frozen on the stream bed) and frazil ice 
(ice crystal suspended in the water) can also have negative impacts on 
trout (Needham and Jones 1959, p. 465). High-elevation streams are 
rarely visited in winter; consequently, it is difficult to document the 
extent to which freezing may impact populations. However, the 
combination of reduced stream flow and reduced snow pack could lead to 
an increased probability of stream freezing in small headwater Rio 
Grande cutthroat trout streams.
    Earlier snowmelt, which leads to less flow in the spring and 
summer, could either benefit Rio Grande cutthroat trout or be 
detrimental. The benefit could come because the young-of-year would 
have a longer growing season before winter. However, as discussed 
above, a longer season of lower flows would lead to increased stream 
temperatures and increased probability of intermittency and drying.
    In summary, it is difficult to project how changes in the 
hydrograph as a result of climate change will affect Rio Grande 
cutthroat trout populations. If growing season is increased, water 
temperatures remain suitable, and the stream does not dry, a beneficial 
effect could occur. If spawning cues are disrupted or egg and fry 
success is reduced because of winter floods or unseasonal extreme 
floods, a negative impact would occur. In addition, stream freezing may 
reduce suitable over-winter habitat or reduce population size in 
susceptible streams.

Extreme Events

    An increase in extreme events such as drought, fires, and floods is 
predicted to occur because of climate change (IPCC 2007a, p. 15). It is 
anticipated that an increase in extreme events will most likely affect 
populations living at the edge of their physiological tolerances. The 
predicted increases in extreme temperature and precipitation events may 
lead to dramatic changes in the distribution of species or to their 
extirpation or extinction (Parmesan and Matthews 2006, p. 344).
    Drought. The relatively short-term drought of the early 2000s had a 
negative impact on or extirpated 14 Rio Grande cutthroat trout 
populations in Colorado and New Mexico (Japhet et al. 2007, pp. 42-44; 
Patten et al. 2007, pp. 14-40). A fifteenth population is thought to 
have been extirpated in 2006 by complete freezing caused by low flow in 
the winter (Ferrell 2006, p. 11). As discussed above, in the 
``Decreased Stream Flow'' section, it is anticipated that a prolonged, 
intense drought would affect many Rio Grande cutthroat trout 
populations, in particular those less

[[Page 27919]]

than 1.5 m (5 ft) wide and less than 8 km (5 mi) long because of their 
small size.
    Most Rio Grande cutthroat trout populations are currently protected 
from downstream populations of nonnative trout by barriers. Downstream 
reaches are larger streams that historically could have provided 
refugia for populations threatened by stream drying. If Rio Grande 
cutthroat trout disperse downstream now, they are lost from their 
conservation population once they pass over the barrier because they 
will not be able to pass back over the barrier moving the upstream 
direction. In the future, downstream water temperatures may be too warm 
to be suitable for Rio Grande cutthroat trout. In addition to stream 
drying, there is a clear association between severe droughts and large 
fires in the Southwest (Swetnam and Baisan 1994, pp. 11, 24, 28), as 
discussed below.
    Fire. Since the mid-1980s, wildfire frequency in western forests 
has nearly quadrupled compared to the average of the period 1970-1986. 
The total area burned is more than six and a half times the previous 
level (Westerling et al. 2006, p. 941). In addition, the average length 
of the fire season during 1987-2003 was 78 days longer compared to 
1970-1986 and the average time between fire discovery and control 
increased from 7.5 days to 37.1 days for the same timeframes 
(Westerling et al. 2006, p. 941). McKenzie et al. (2004, p. 893) 
suggest, based on models, that the length of the fire season will 
likely increase further and that fires in the western United States 
will be more frequent and more severe. In particular, they found that 
fire in New Mexico appears to be acutely sensitive to summer climate 
and temperature changes and may respond dramatically to climate 
warming.
    Changes in relative humidity, especially drying over the western 
United States, are also projected to increase the number of days of 
high fire danger (Brown et al. 2004, p. 365). High-elevation, subalpine 
forests in the Rocky Mountains typically experience infrequent (i.e., 
one to many centuries), high severity crown fires (Schoennagel et al. 
2004, p. 664). These fires usually occur in association with extremely 
dry regional climate patterns (Swetnam and Baisan 1994, p. 28; 
Schoennagel et al. 2004, p. 664). Short drying periods do not create 
the conditions appropriate for fire in these typically cool, humid 
forests. Schoennagel et al. (2004, p. 665, 666) conclude that recent 
increases in the area burned in subalpine forests are not attributable 
to fire suppression but that variation in climate exerts the largest 
influence on the size, timing, and severity of the fires. In contrast, 
low-elevation, ponderosa pine forests in the Rocky Mountains were 
historically characterized by frequent, low-severity fires (Schoennagel 
et al. 2004, p. 669). Fire suppression has significantly increased 
ladder fuels (fuels that allow fire to climb from the forest floor to 
the tops of trees) and tree densities leading to unprecedented high-
severity fires in these ecosystems (Schoennagel et al. 2004, p. 669). 
Rio Grande cutthroat trout streams occur in both forest types.
    As discussed in the ``Fire'' section in Factor A above, because of 
the observed and predicted increase in fire season length; the 
predicted increase in frequency and severity of fires; the observation 
that fuel treatment is only effective in low-elevation, ponderosa pine 
forests; the expectation of an increase in the frequency of hot 
extremes, heat waves, and heavy precipitation (IPCC 2007a, p. 15); and 
the fact that most Rio Grande cutthroat trout streams occur within a 
forested landscape, we conclude that wildfire associated with climate 
change will exacerbate habitat loss to Rio Grande cutthroat trout 
populations across their range.
    Floods. The life history of salmonids is tied to the timing of 
floods (Fausch et al. 2001, p. 1440). A change in timing or magnitude 
of floods can scour the streambed, destroy eggs, or displace recently 
emerged fry downstream (Erman et al. 1988, p. 2199; Montgomery et al. 
1999, p. 378; Fausch et al. 2001, p. 1440). Floods that occur after 
intense wildfires that have denuded the watershed are also a threat. As 
described above, in the ``Fire'' section under Factor A, several 
streams in the Southwest have had populations of trout extirpated as a 
result of ash flows which occurred after fire (Rinne 1996, p. 654; 
Brown et al. 2001, p. 142; Patten et al. 2007, p. 33). Consequently, an 
increase in rain or snow events, intense precipitation that is 
unseasonable, or precipitation that occurs after fire could extirpate 
affected Rio Grande cutthroat trout populations.
    In summary, extreme events, especially widespread fire and drought, 
will likely affect Rio Grande cutthroat trout populations in the 
foreseeable future through population extirpation, extreme population 
reduction, or habitat reduction. Several Rio Grande cutthroat trout 
populations have already been impacted by drought. Fire has thus far 
primarily affected nonnative trout streams within the range of Rio 
Grande cutthroat trout, but there is no safeguard for Rio Grande 
cutthroat trout streams. The impact of a change in the timing of runoff 
may be significant but is more difficult to predict.

Climate Change Summary

    The extent to which climate change will affect Rio Grande cutthroat 
trout is not known with certainty at this time. Preliminary projections 
point to a possible rangewide negative impact through increased water 
temperatures, decreased stream flow, a change in hydrograph, and an 
increased occurrence of extreme events, which will all tend to 
exacerbate the threats to the Rio Grande cutthroat trout and its 
habitat discussed under Factors A and C above. Although the extent that 
the global climate will change in the future is not known, even a 
minimal increase in temperature will lead to increased habitat 
unsuitability and will exacerbate most other known threats to the 
subspecies.

Fisheries Management

    Future management of Rio Grande cutthroat trout will depend in part 
on the use of hatchery-reared fish. Although hatcheries can produce 
many fish in a short period of time, the use of hatchery fish is not 
without risks (Busack and Currens 1995, pp. 73-78). Two recent papers 
have explored the risks of captive propagation used to supplement 
species that are declining in the wild (Araki et al. 2007, Frankham 
2007). Araki et al. (2007, p. 102) found that there was approximately a 
40 percent decline in reproductive capabilities per captive-reared 
generation when steelhead trout (Oncorhynchus mykiss) were moved to 
natural environments. Frankham (2007, p. 2) notes that characteristics 
selected for under captive breeding conditions are overwhelmingly 
disadvantageous in the natural environment. Minimizing the number of 
generations in captivity or making the captive environment similar to 
the wild environment are effective means for minimizing genetic 
adaptation to captivity (Frankham 2007, pp. 4, 5).
    The history of brood stock management in New Mexico has been marked 
by many challenges (Cowley and Pritchard 2003, pp. 12, 13). The most 
recent challenges came from whirling disease infection at Seven Springs 
Hatchery and the discovery that the brood stock was introgressed with 
Yellowstone cutthroat trout (Patten et al. 2007, p. 42). The hatchery 
was refurbished to eliminate M. cerebralis and the brood stock program 
was restarted in 2005 (Patten et al. 2007, p. 42). A recently revised 
brood stock management plan was completed for

[[Page 27920]]

New Mexico (Cowley and Pritchard 2003).
    Although the intent of fisheries management is positive, fisheries 
management may result in unanticipated outcomes. For example, Costilla 
Creek restoration efforts were unfortunately marred by the introduction 
of rainbow trout into the recently reclaimed stream (Patten et al. 
2007, p. 101, Appendices VIII-X). The rainbow trout came from Seven 
Springs Hatchery, even though this hatchery is designated as a Rio 
Grande cutthroat trout facility (NMDGF 2002, p. 28; Pattten et al. 
2007, p. 379). It is unclear why Seven Springs Hatchery was holding 
rainbow trout. Through a coordinated effort, managers believe they 
captured most, if not all, of the rainbow trout that were stocked into 
Costilla Creek along with Rio Grande cutthroat trout (Patten et al. 
2007, pp. 18, 102). While electrofishing to recover the rainbow trout, 
two brook trout were also caught, indicating that the lower barrier was 
compromised, not all the fish were killed during treatment, or that an 
angler had released the fish above the barrier. In addition, because 
the stocked Rio Grande cutthroat trout came from Seven Springs Hatchery 
before the introgression with Yellowstone cutthroat trout was 
discovered, the Rio Grande cutthroat trout that were stocked were 
slightly introgressed (Patten et al. 2007, p. 102). For these reasons, 
relying on hatchery-reared Rio Grande cutthroat trout does not provide 
certainty that repatriation will be successful.
    Fisheries managers have worked very hard in the last several years 
to monitor populations, check and maintain barriers, test the genetic 
purity of populations, test streams for whirling disease, fund 
research, and reintroduce populations into appropriate streams (Patten 
et al. 2007, pp. 4-19; Japhet et al. 2007, pp. 22-27). New populations 
have been established in Costilla, South Ponil, Leandro, and Capulin 
creeks in New Mexico and in Big Springs, East Costilla, and West 
Costilla creeks in Colorado. Populations were restarted in Cat Creek 
and Little Medano Creek, Colorado, after being lost to the drought 
(Japhet et al. 2007, pp. 42-44). In addition, major restoration 
projections have gone through environmental review and are in progress 
on Placer Creek, Comanche Creek, and Costilla Creek. Completion of 
these projects will contribute to the long-term persistence of Rio 
Grande cutthroat trout. The USFS, BLM, and NPS have been active 
partners in project implementation and have completed many miles of 
detailed stream surveys, which adds greatly to our knowledge of habitat 
condition.
    New Mexico Tribes and Pueblos have recently taken initiatives to 
restore Rio Grande cutthroat trout on their homelands. The Mescalero 
Apache Tribe began inventorying their streams to determine presence, 
and has reopened the Mescalero Tribal Fish Hatchery. The Tribe hopes to 
establish a Rio Grande cutthroat trout brood stock and raise Rio Grande 
cutthroat trout to support native fish restoration projects on Tribal 
lands. Santa Clara Pueblo received a Tribal Wildlife grant for nearly 
$200,000 for Rio Grande cutthroat trout restoration. The Pueblo is in 
the initial phases of project planning for restoring the Santa Clara 
Creek watershed. Nambe Pueblo has also expressed an interest in Rio 
Grande cutthroat trout restoration and is working in collaboration with 
USFS, the Service, Southwest Tribal Fisheries Commission (SWTFC), and 
NMDGF to formulate a restoration plan to restore Rio Grande cutthroat 
trout in the Nambe River watershed. The Jicarilla Apache Nation has 
also been involved in Rio Grande cutthroat trout restoration and plans 
to expand their restoration efforts to additional creeks on the 
reservation in the near future. The SWTFC, an organization composed of 
southwestern Native American tribes, has developed a Memorandum of 
Understanding with NMDGF to acquire Rio Grande cutthroat trout eggs for 
juvenile and adult production in support of tribal restoration Rio 
Grande cutthroat trout projects. Currently, the Memorandum is still 
awaiting approval by both participants. If successful, these actions 
would provide further conservation for Rio Grande cutthroat trout.
    The Santa Fe National Forest, led by their fisheries biologist, has 
been very proactive about public education. They estimate that up until 
2006 their ``Respect the Rio'' program directly reached over 9,300 
people (Ferrell 2006, p. 16). They developed the Rio Grande Cutthroat 
Trout Life Cycle Game, which has traveled to classrooms, Earth Day 
events, and Kids' Fishing Day celebrations (Ferrell 2006, p. 15). The 
game has also been translated into Spanish to reach students who speak 
English as a second language. It is estimated that over 1,000 children 
and adults have played the game.
    In New Mexico, a Rio Grande cutthroat trout Working Group meets 
monthly to discuss Rio Grande cutthroat trout conservation, projects, 
and volunteer opportunities, and to coordinate and communicate efforts 
among the participants. Regular members are NMDGF, the Service, Trout 
Unlimited, New Mexico Trout, and the USFS. The members are committed to 
Rio Grande cutthroat trout conservation.
    One obstacle to fisheries managers in New Mexico has been the 
difficult process of approval for chemical treatment of streams. In 
August 2004, the New Mexico Game Commission voted to prohibit the use 
of piscicides in New Mexico (Patten et al. 2007, p. 102). This decision 
effectively terminated a project on Animas Creek, Gila National Forest, 
and has made stream restoration project approval difficult. Another 
obstacle to successful stream renovation is the stocking of nonnative 
trout by anglers into streams that have been treated to remove them 
(Japhet et al. 2007, p. 17). Although education and regulation may 
help, there is no known way to stop this illegal activity.

Summary of Factor E

    Fisheries management is integral to the conservation of Rio Grande 
cutthroat trout. Although there are some risks associated with 
fisheries management, we conclude that the benefits outweigh the risks. 
We also conclude that the best scientific and commercial information 
available to us indicates that the threats facing Rio Grande cutthroat 
trout will be exacerbated by climate change. Continued management 
actions to connect fragmented populations are essential. However, at 
this time, it is not clear that management actions can outpace some of 
the projected effects of climate change.

Finding

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
faced by Rio Grande cutthroat trout. We have reviewed information 
supplied to us by State and Federal agencies, peer-reviewed literature, 
comments from private citizens, and other unpublished documents. The 
information summarized in this status review includes substantial 
information that was not available at the time of our 2002 finding (67 
FR 39936). On the basis of this review, we find that listing of Rio 
Grande cutthroat trout as threatened or endangered is warranted, due to 
a combination of population fragmentation, isolation, small population 
size, nonnative trout, drought, and fire. We anticipate these threats 
will be compounded by the projected effects of climate change. However, 
listing of the Rio Grande cutthroat trout is precluded at this time by 
pending proposals for other species with higher listing priorities and 
actions.

[[Page 27921]]

    In the context of the Act, the term ``threatened species'' means 
any species (or subspecies or, for vertebrates, distinct population 
segments) that is likely to become an endangered species within the 
foreseeable future throughout all or a significant portion of its 
range. The term ``endangered species'' means any species that is in 
danger of extinction throughout all or a significant portion of its 
range. The Act does not 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 Act are the threats that now confront the species and 
the probability that the species will persist into ``the foreseeable 
future.'' The Act does not define the term ``foreseeable future.'' 
However, we consider the ``foreseeable future'' to be 20 to 30 years, 
which equates to approximately 4 to 10 Rio Grande cutthroat trout 
generations, depending on the productivity of the environment. We find 
that this is both reasonable and appropriate for the present status 
review 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.
    Evidence shows that populations of Rio Grande cutthroat trout have 
been greatly reduced over the last 200 years. The range of Rio Grande 
cutthroat trout has contracted northward and populations are primarily 
restricted to high-elevation headwater streams. We attribute the 
decline in the distribution of Rio Grande cutthroat trout to habitat 
degradation and the introduction of nonnative sport fish into Rio 
Grande cutthroat trout habitat that began in the late 1800s. The wide 
distribution of rainbow trout and nonnative cutthroat trout have 
compromised Rio Grande cutthroat trout populations through competition, 
hybridization, and predation. These introduced fish have expanded and 
colonized new habitat and formed naturally reproducing populations that 
occupy the former, and in some cases current, range of Rio Grande 
cutthroat trout.
    We find that populations we considered secure in 2002 suffered 
severe to moderate population declines. We considered 13 populations 
secure in 2002, and now we find that only 8 populations (5 identified 
in 2002, 3 new populations) would meet our definition of long-term 
persistence (over 2,500 fish, 9.6 km (6 mi) of occupied habitat, no 
nonnatives present). Although 97 additional conservation populations 
exist, they all are affected by one or more threats (e.g., small 
population size, short stream length, poor habitat quality, nonnative 
trout) that we consider significant enough to threaten their long-term 
survival. The overarching threat that magnifies the problems for each 
individual population is fragmentation. Over 90 percent of Rio Grande 
cutthroat trout populations exist in stream fragments. Consequently, 
recolonization of streams cannot occur after a natural disaster occurs 
and populations are much more susceptible to extirpation.
    Because of the increases in air temperature that have already been 
documented in the Southwest, and other changes that have been 
documented in hydrology, fire patterns, and the life history of animals 
in the region, there is evidence that the effects of climate change are 
already occurring in the range of Rio Grande cutthroat trout. Every 
aspect of climate change we examined will likely have a negative effect 
on Rio Grande cutthroat trout. Rio Grande cutthroat trout populations 
are currently surviving with multiple stressors. Adding the effects of 
climate change on these populations may exacerbate the existing threats 
and stressors on the species.
    There is documented commitment of agency personnel, tribes, and 
private landowners to continue conservation efforts for Rio Grande 
cutthroat trout. This is evidenced by the lists of accomplishments the 
States and agencies have provided to us. Both State and Federal 
agencies have been actively involved in Rio Grande cutthroat trout 
management. Several habitat restoration projects are in progress and 
several others are planned. It is too early to determine the level of 
success of current large watershed projects as they have not been fully 
completed and evaluated.

Listing Priority Number

    In accordance with guidance we published on September 21, 1983, we 
assign a Listing Priority Number (LPN) to each candidate species (48 FR 
43098). Such a priority ranking guidance system is required under 
section 4(h)(3) of the Act (16 U.S.C. 1533(h)(3)). Using this guidance, 
we assign each candidate an LPN of 1 to 12, depending on the magnitude 
of threats (high vs. moderate to low); immediacy of threats (imminent 
or non-imminent); and taxonomic status of the species, in order of 
priority (monotypic genus (i.e., a species that is the sole member of a 
genus), species, subspecies, distinct population segment, or 
significant portion of the range). The lower the listing priority 
number, the higher the listing priority (that is, a species with an LPN 
of 1 would have the highest listing priority).
    Many of the threats to this subspecies could result in complete 
loss of a given population at any time (e.g., fire, disease, nonnative 
introgression). However, because there are many known conservation 
populations and because many populations are being actively managed, 
the threats to this subspecies as a whole are considered moderate.
    An increase in average mean air temperature of just over 1 [deg]C 
(2.5 [deg]F) in Arizona and just under 1 [deg]C (1.8 [deg]F) in New 
Mexico since 1976 (Parmesan and Galbraith 2004, pp. 18, 19; State of 
New Mexico 2006, p. 5; Lenart 2007, p. 4) suggest that climate change 
is already occurring in the Southwest. Coldwater species like Rio 
Grande cutthroat trout are expected to be among the most sensitive 
species to climate change. Water temperatures in some Rio Grande 
cutthroat trout streams are already elevated beyond recommended 
temperatures for coldwater trout. At least 14 Rio Grande cutthroat 
trout streams either dried up or had populations negatively affected by 
the 2002 drought. Rio Grande cutthroat trout populations already face 
multiple stresses such as nonnative trout, fragmented habitat, and 
limited habitat. The additional effects of climate change are expected 
to cause population extirpations and population bottlenecks. 
Consequently, threats to this species are considered imminent. 
Therefore, based on the moderate magnitude and immediacy of threats, we 
have given this subspecies an LPN of 9.

Preclusion and Expeditious Progress

    Preclusion is a function of the listing priority of a species in 
relation to the resources that are available and competing demands for 
those resources. Thus, in any given fiscal year (FY), multiple factors 
dictate whether it will be possible to undertake work on a proposed 
listing regulation or whether promulgation of such a proposal is 
warranted but precluded by higher priority listing actions.
    The resources available for listing actions are determined through 
the annual Congressional appropriations process. The appropriation for 
the Listing Program is available to support work involving the 
following listing actions: proposed and final listing rules; 90-day and 
12-month findings on petitions to add species to the Lists of 
Endangered and Threatened Wildlife and Plants (Lists) or to change the 
status

[[Page 27922]]

of a species from threatened to endangered; annual determinations on 
prior ``warranted but precluded'' petition findings as required under 
section 4(b)(3)(C)(i) of the Act; proposed and final rules designating 
critical habitat; and litigation-related, administrative, and program 
management functions (including preparing and allocating budgets, 
responding to Congressional and public inquiries, and conducting public 
outreach regarding listing and critical habitat). The work involved in 
preparing various listing documents can be extensive and may include, 
but is not limited to: gathering and assessing the best scientific and 
commercial data available and conducting analyses used as the basis for 
our decisions; writing and publishing documents; and obtaining, 
reviewing, and evaluating public comments and peer review comments on 
proposed rules and incorporating relevant information into final rules. 
The number of listing actions that we can undertake in a given year 
also is influenced by the complexity of those listing actions; that is, 
more complex actions generally are more costly. For example, during the 
past several years, the cost (excluding publication costs) for 
preparing a 12-month finding, without a proposed rule, has ranged from 
approximately $11,000 for one species with a restricted range and 
involving a relatively uncomplicated analysis to $305,000 for another 
species that is wide-ranging and involving a complex analysis.
    We cannot spend more than is appropriated for the Listing Program 
without violating the Anti-Deficiency Act (see 31 U.S.C. 
1341(a)(1)(A)). In addition, in FY 1998 and for each fiscal year since 
then, Congress has placed a statutory cap on funds which may be 
expended for the Listing Program, equal to the amount expressly 
appropriated for that purpose in that fiscal year. This cap was 
designed to prevent funds appropriated for other functions under the 
Act (for example, recovery funds for removing species from the Lists), 
or for other Service programs, from being used for Listing Program 
actions (see House Report 105-163, 105th Congress, 1st Session, July 1, 
1997).
    Recognizing that designation of critical habitat for species 
already listed would consume most of the overall Listing Program 
appropriation, Congress also put a critical habitat subcap in place in 
FY 2002 and has retained it each subsequent year to ensure that some 
funds are available for other work in the Listing Program: ``The 
critical habitat designation subcap will ensure that some funding is 
available to address other listing activities'' (House Report No. 107-
103, 107th Congress, 1st Session, June 19, 2001). In FY 2002 and each 
year until FY 2006, the Service has had to use virtually the entire 
critical habitat subcap to address court-mandated designations of 
critical habitat, and consequently none of the critical habitat subcap 
funds have been available for other listing activities. In FY 2007, we 
were able to use some of the critical habitat subcap funds to fund 
proposed listing determinations for high-priority candidate species; we 
expect to also be able to do this in FY 2008.
    Thus, through the listing cap, the critical habitat subcap, and the 
amount of funds needed to address court-mandated critical habitat 
designations, Congress and the courts have in effect determined the 
amount of money available for other listing activities. Therefore, the 
funds in the listing cap, other than those needed to address court-
mandated critical habitat for already listed species, set the limits on 
our determinations of preclusion and expeditious progress.
    Congress also recognized that the availability of resources was the 
key element in deciding whether, when making a 12-month petition 
finding, we would prepare and issue a listing proposal or make a 
``warranted but precluded'' finding for a given species. The Conference 
Report accompanying Public Law 97-304, which established the current 
statutory deadlines and the warranted-but-precluded finding, states (in 
a discussion on 90-day petition findings that by its own terms also 
covers 12-month findings) that the deadlines were ``not intended to 
allow the Secretary to delay commencing the rulemaking process for any 
reason other than that the existence of pending or imminent proposals 
to list species subject to a greater degree of threat would make 
allocation of resources to such a petition [that is, for a lower-
ranking species] unwise.''
    In FY 2008, expeditious progress is that amount of work that can be 
achieved with $8,206,940, which is the amount of money that Congress 
appropriated for the Listing Program at this time (that is, the portion 
of the Listing Program funding not related to critical habitat 
designations for species that are already listed). Our process is to 
make our determinations of preclusion on a nationwide basis to ensure 
that the species most in need of listing will be addressed first and 
also because we allocate our listing budget on a nationwide basis. The 
$8,206,940 for listing activities (that is, the portion of the Listing 
Program funding not related to critical habitat designations for 
species that already are listed) will be used to fund work in the 
following categories: Compliance with court orders and court-approved 
settlement agreements requiring that petition findings or listing 
determinations be completed by a specific date; section 4 (of the Act) 
listing actions with absolute statutory deadlines; essential 
litigation-related, administrative, and program management functions; 
and high-priority listing actions. The allocations for each specific 
listing action are identified in the Service's FY 2008 Draft Allocation 
Table (part of our administrative record). We are working on completing 
our allocation at this time. More funds are available in FY 2008 than 
in previous years to work on listing actions that are not the subject 
of court orders or court-approved settlement agreements.
    We currently have more than 120 species with an LPN of 2. 
Therefore, we further rank the candidate species with an LPN of 2 by 
using the following extinction-risk type criteria: International Union 
for the Conservation of Nature and Natural Resources (IUCN) Red list 
status/rank, Heritage rank (provided by NatureServe), Heritage threat 
rank (provided by NatureServe), and species currently with fewer than 
50 individuals, or 4 or fewer populations. Those species with the 
highest IUCN rank (critically endangered), the highest Heritage rank 
(G1), the highest Heritage threat rank (substantial, imminent threats), 
and currently with fewer than 50 individuals, or fewer than 4 
populations, comprise a list of approximately 40 candidate species 
(``Top 40''). These 40 candidate species have the highest priority to 
receive funding to work on a proposed listing determination. To be more 
efficient in our listing process, as we work on proposed rules for 
these species in the next several years, we are preparing multi-species 
proposals when appropriate, and these may include species with lower 
priority if they overlap geographically or have the same threats as a 
species with an LPN of 2. In addition, available staff resources are 
also a factor in determining high-priority species provided with 
funding. Finally, proposed rules for reclassification of threatened 
species to endangered are lower priority, since the listing of the 
species already affords the protection of the Act and implementing 
regulations. We assigned the Rio Grande cutthroat trout an LPN of 9, 
based on our finding that the subspecies faces

[[Page 27923]]

threats of moderate magnitude that are imminent.
    As explained above, a determination that listing is warranted but 
precluded must also demonstrate that expeditious progress is being made 
to add or remove qualified species to and from the Lists of Endangered 
and Threatened Wildlife and Plants. (We note that we do not discuss 
specific actions taken on progress towards removing species from the 
Lists because that work is conducted using appropriations for our 
Recovery program, a separately budgeted component of the Endangered 
Species Program. As explained above in our description of the statutory 
cap on Listing Program funds, the Recovery Program funds and actions 
supported by them cannot be considered in determining expeditious 
progress made in the Listing Program.) As with our ``precluded'' 
finding, expeditious progress in adding qualified species to the Lists 
is a function of the resources available and the competing demands for 
those funds. Our expeditious progress in FY 2007 in the Listing 
Program, up to the date of making this finding for the Rio Grande 
cutthroat trout, included preparing and publishing the following 
determinations:

                                        FY 2007 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
        Publication date                   Title                   Actions                   FR pages
----------------------------------------------------------------------------------------------------------------
10/11/2006.....................  Withdrawal of the          Final withdrawal,     71 FR 59700-59711.
                                  Proposed Rule to List      Threats eliminated.
                                  the Cow Head Tui Chub
                                  (Gila biocolor
                                  vaccaceps) as Endangered.
10/11/2006.....................  Revised 12-Month Finding   Notice of 12-month    71 FR 59711-59714.
                                  for the Beaver Cave        petition finding,
                                  Beetle                     Not warranted.
                                  (Pseudanophthalmus
                                  major).
11/14/2006.....................  12-Month Finding on a      Notice of 12-month    71 FR 66292-66298.
                                  Petition to List the       petition finding,
                                  Island Marble Butterfly    Not warranted.
                                  (Euchloe ausonides
                                  insulanus) as Threatened
                                  or Endangered.
11/14/2006.....................  90-Day Finding for a       Notice of 90-day      71 FR 66298-66301.
                                  Petition to List the       petition finding,
                                  Kennebec River             Substantial.
                                  Population of Anadromous
                                  Atlantic Salmon as Part
                                  of the Endangered Gulf
                                  Of Maine Distinct
                                  Population Segment.
11/21/2006.....................  90-Day Finding on a        Notice of 90-day      71 FR 67318-67325.
                                  Petition To List the       petition finding,
                                  Columbian Sharp-Tailed     Not substantial.
                                  Grouse as Threatened or
                                  Endangered.
12/5/2006......................  90-Day Finding on a        Notice of 90-day      71 FR 70483-70492.
                                  Petition To List the       petition finding,
                                  Tricolored Blackbird as    Not substantial.
                                  Threatened or Endangered.
12/6/2006......................  12-Month Finding on a      Notice of 12-month    71 FR 70717-70733.
                                  Petition To List the       petition finding,
                                  Cerulean Warbler           Not warranted.
                                  (Dendroica cerulea) as
                                  Threatened with Critical
                                  Habitat.
12/6/2006......................  90-Day Finding on a        Notice of 90-day      71 FR 70715-70717.
                                  Petition To List the       Petition Finding,
                                  Upper Tidal Potomac        Not substantial.
                                  River Population of the
                                  Northern Water Snake
                                  (Nerodia sipedon) as an
                                  Endangered Distinct
                                  Population Segment.
12/14/2006.....................  90-Day Finding on a        Notice of 5-year      71 FR 75215-75220.
                                  Petition to Remove the     Review, Initiation.
                                  Uinta Basin Hookless      Notice of 90-day
                                  Cactus From the List of    petition finding,
                                  Endangered and             Not substantial.
                                  Threatened Plants; 90-    Notice of 90-day
                                  Day Finding on a           petition finding,
                                  Petition To List the       Substantial.
                                  Pariette Cactus as
                                  Threatened or Endangered.
12/19/2006.....................  Withdrawal of Proposed     Notice of             71 FR 76023-76035.
                                  Rule to List Penstemon     withdrawal, More
                                  grahamii (Graham's         abundant than
                                  beardtongue) as            believed, or
                                  Threatened With Critical   diminished threats.
                                  Habitat.
12/19/2006.....................  90-Day Finding on          Notice of 90-day      71 FR 76057-76079.
                                  Petitions to List the      petition finding,
                                  Mono Basin Area            Not substantial.
                                  Population of the
                                  Greater Sage-Grouse as
                                  Threatened or Endangered.
1/9/2007.......................  12-Month Petition Finding  Notice of 12-month    72 FR 1063-1099.
                                  and Proposed Rule To       petition finding,
                                  List the Polar Bear        Warranted.
                                  (Ursus maritimus) as      Proposed Listing,
                                  Threatened Throughout      Threatened.
                                  Its Range; Proposed Rule.
1/10/2007......................  Endangered and Threatened  Clarification of      72 FR 1186-1189.
                                  Wildlife and Plants;       findings.
                                  Clarification of
                                  Significant Portion of
                                  the Range for the
                                  Contiguous United States
                                  Distinct Population
                                  Segment of the Canada
                                  Lynx.
1/12/2007......................  Withdrawal of Proposed     Notice of             72 FR 1621-1644.
                                  Rule To List Lepidium      withdrawal, More
                                  papilliferum (Slickspot    abundant than
                                  Peppergrass).              believed, or
                                                             diminished threats.
2/2/2007.......................  12-Month Finding on a      Notice of 12-month    72 FR 4967-4997.
                                  Petition To List the       petition finding,
                                  American Eel as            Not warranted.
                                  Threatened or Endangered.
2/13/2007......................  90-Day Finding on a        Notice of 90-day      72 FR 6699-6703.
                                  Petition To List the       petition finding,
                                  Jollyville Plateau         Substantial.
                                  Salamander as Endangered.
2/13/2007......................  90-Day Finding on a        Notice of 90-day      72 FR 6703-6707.
                                  Petition To List the San   petition finding,
                                  Felipe Gambusia as         Not substantial.
                                  Threatened or Endangered.
2/14/2007......................  90-Day Finding on A        Notice 90-day         72 FR 6998-7005.
                                  Petition to List           petition finding,
                                  Astragalus debequaeus      Not substantial.
                                  (DeBeque milkvetch) as
                                  Threatened or Endangered.
2/21/2007......................  90-Day Finding on a        Notice of 5-year      72 FR 7843-7852.
                                  Petition To Reclassify     Review, Initiation.
                                  the Utah Prairie Dog      Notice of 90-day
                                  From Threatened to         petition finding,
                                  Endangered and             Not substantial.
                                  Initiation of a 5-Year
                                  Review.
3/8/2007.......................  90-Day Finding on a        Notice of 90-day      72 FR 10477-10480.
                                  Petition To List the       petition finding,
                                  Monongahela River Basin    Not substantial.
                                  Population of the
                                  Longnose Sucker as
                                  Endangered.
3/29/2007......................  90-Day Finding on a        Notice 90-day         72 FR 14750-14759.
                                  Petition To List the       petition finding,
                                  Siskiyou Mountains         Substantial.
                                  Salamander and Scott Bar
                                  Salamander as Threatened
                                  or Endangered.

[[Page 27924]]

 
4/24/2007......................  Revised 12-Month Finding   Notice of 12-month    72 FR 20305-20314.
                                  for Upper Missouri River   petition finding,
                                  Distinct Population        Not warranted.
                                  Segment of Fluvial
                                  Arctic Grayling.
5/2/2007.......................  12-Month Finding on a      Notice of 12-month    72 FR 24253-24263.
                                  Petition to List the       petition finding,
                                  Sand Mountain Blue         Not warranted.
                                  Butterfly (Euphilotes
                                  pallescens ssp.
                                  arenamontana) as
                                  Threatened or Endangered
                                  with Critical Habitat.
5/22/2007......................  Status of the Rio Grande   Notice of Review....  72 FR 28664-28665.
                                  Cutthroat Trout.
5/30/2007......................  90-Day Finding on a        Notice of 90-day      72 FR 29933-29941.
                                  Petition To List the Mt.   petition finding,
                                  Charleston Blue            Substantial.
                                  Butterfly as Threatened
                                  or Endangered.
6/5/2007.......................  12-Month Finding on a      Notice of Review....  72 FR 31048-31049.
                                  Petition To List the
                                  Wolverine as Threatened
                                  or Endangered.
6/6/2007.......................  90-Day Finding on a        Notice 90-day         72 FR 31256-31264.
                                  Petition To List the       Petition Finding,
                                  Yellow-Billed Loon as      Substantial.
                                  Threatened or Endangered.
6/13/2007......................  12-Month Finding for a     Notice 12-month       72 FR 32589-32605.
                                  Petition To List the       petition finding,
                                  Colorado River Cutthroat   Not warranted.
                                  Trout as Threatened or
                                  Endangered.
6/25/2007......................  12-Month Finding on a      Notice amended 12-    72 FR 34657-34661.
                                  Petition To List the       month petition
                                  Sierra Nevada Distinct     finding, Warranted
                                  Population Segment of      but precluded.
                                  the Mountain Yellow-
                                  Legged Frog (Rana
                                  muscosa).
7/5/2007.......................  12-Month Finding on a      Notice 12-month       72 FR 36635-36646.
                                  Petition To List the       petition finding,
                                  Casey's June Beetle        Warranted but
                                  (Dinacoma caseyi) as       precluded.
                                  Endangered With Critical
                                  Habitat.
8/15/2007......................  90-Day Finding on a        Notice 90-day         72 FR 45717-45722.
                                  Petition To List the       Petition Finding,
                                  Yellowstone National       Not substantial.
                                  Park Bison Herd as
                                  Endangered.
08/16/2007.....................  90-Day Finding on a        Notice 90-day         72 FR 46023-46030.
                                  Petition To List           Petition Finding,
                                  Astragalus anserinus       Substantial.
                                  (Goose Creek milk-vetch)
                                  as Threatened or
                                  Endangered.
8/28/2007......................  12-Month Finding on a      Notice of Review....  72 FR 49245-49246.
                                  Petition To List the
                                  Gunnison's Prairie Dog
                                  as Threatened or
                                  Endangered.
9/11/2007......................  90-Day Finding on a        Notice 90-day         72 FR 51766-51770.
                                  Petition To List Kenk's    Petition Finding,
                                  Amphipod, Virginia Well    Not substantial.
                                  Amphipod, and the
                                  Copepod Acanthocyclops
                                  columbiensis as
                                  Endangered.
9/18/2007......................  12-month Finding on a      Notice 12-month       72 FR 53211-53222.
                                  Petition To List           petition finding
                                  Sclerocactus brevispinus   for uplisting,
                                  (Pariette cactus) as an    Warranted but
                                  Endangered or Threatened   precluded.
                                  Species; Taxonomic
                                  Change From Sclerocactus
                                  glaucus to Sclerocactus
                                  brevispinus, S. glaucus,
                                  and S. wetlandicus.
----------------------------------------------------------------------------------------------------------------

    In FY 2007, we provided funds to work on proposed listing 
determinations for the following high-priority species: 3 southeastern 
aquatic species (Georgia pigtoe, interrupted rocksnail, and rough 
hornsnail), 2 Oahu plants (Doryopteris takeuchii, Melicope hiiakae), 31 
Kauai species (Kauai creeper, Drosophila attigua, Astelia waialealae, 
Canavalia napaliensis, Chamaesyce eleanoriae, Chamaesyce remyi var. 
kauaiensis, Chamaesyce remyi var. remyi, Charpentiera densiflora, 
Cyanea eleeleensis, Cyanea kuhihewa, Cyrtandra oenobarba, Dubautia 
imbricata ssp. imbricata, Dubautia plantaginea ssp. magnifolia, 
Dubautia waialealae, Geranium kauaiense, Keysseria erici, Keysseria 
helenae, Labordia helleri, Labordia pumila, Lysimachia daphnoides, 
Melicope degeneri, Melicope paniculata, Melicope puberula, Myrsine 
mezii, Pittosporum napaliense, Platydesma rostrata, Pritchardia hardyi, 
Psychotria grandiflora, Psychotria hobdyi, Schiedea attenuata, 
Stenogyne kealiae), 4 Hawaiian damselflies (Megalagrion nesiotes, 
Megalagrion leptodemas, Megalagrion oceanicum, Megalagrion pacificum), 
and one Hawaiian plant (Phyllostegia hispida (no common name)). In FY 
2008, we are continuing to work on these listing proposals (we are now 
including an additional 17 species in the Kauai species proposed 
listing determination package). In addition, we are continuing to work 
on several other determinations listed below, which we funded in FY 
2007 and are scheduled to complete in FY 2008.

         Actions Funded in FY 2007 That Have Yet To Be Completed
------------------------------------------------------------------------
                Species                               Action
------------------------------------------------------------------------
 Actions Subject to Court Order/
 Settlement Agreement:
    Western sage grouse................  90-day petition finding
                                          (remand).
Actions with Statutory Deadlines:
    Polar bear.........................  Final listing determination.
    Ozark chinquapin...................  90-day petition finding.
    Tucson shovel-nosed snake..........  90-day petition finding.
    Gopher tortoise--Florida population  90-day petition finding.
    Sacramento valley tiger beetle.....  90-day petition finding.
    Eagle lake trout...................  90-day petition finding.
    Smooth billed ani..................  90-day petition finding.
    Mojave ground squirrel.............  90-day petition finding.
    Gopher Tortoise--eastern population  90-day petition finding.
    Bay Springs salamander.............  90-day petition finding.
    Tehachapi slender salamander.......  90-day petition finding.

[[Page 27925]]

 
    Evening primrose...................  90-day petition finding.
    Northern leopard frog..............  90-day petition finding.
    Cactus ferruginous pygmy owl.......  90-day petition finding.
------------------------------------------------------------------------

    Our expeditious progress so far in FY 2008 in the Listing Program, 
includes preparing and publishing the following:

                                        FY 2008 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
        Publication date                   Title                   Actions                   FR pages
----------------------------------------------------------------------------------------------------------------
10/09/2007.....................  90-Day Finding on a        Notice of 90-day      72 FR 57278-57283.
                                  Petition To List the       Petition Finding,
                                  Black-Footed Albatross     Substantial.
                                  (Phoebastria nigripes)
                                  as Threatened or
                                  Endangered.
10/09/2007.....................  90-Day Finding on a        Notice of 90-day      72 FR 57273-57276.
                                  Petition To List the       Petition Finding,
                                  Giant Palouse Earthworm    Not Substantial.
                                  as Threatened or
                                  Endangered.
10/23/2007.....................  90-Day Finding on a        Notice of 90-day      72 FR 59983-59989.
                                  Petition To List the       Petition Finding,
                                  Mountain Whitefish         Not Substantial.
                                  (Prosopium williamsoni)
                                  in the Big Lost River,
                                  ID, as Threatened or
                                  Endangered.
 10/23/2007....................  90-Day Finding on a        Notice of 90-day      72 FR 59979-59983.
                                  Petition To List the       Petition Finding,
                                  Summer-Run Kokanee         Not substantial.
                                  Population in Issaquah
                                  Creek, WA, as Threatened
                                  or Endangered.
11/08/2007.....................  Response to Court on       Response to Court...  72 FR 63123-63140.
                                  Significant Portion of
                                  the Range, and
                                  Evaluation of Distinct
                                  Population Segments, for
                                  the Queen Charlotte
                                  Goshawk.
12/13/2007.....................  12-Month Finding on a      Notice of 12-month    72 FR 71039-71054.
                                  Petition To List the       Petition Finding,
                                  Jollyville Plateau         Warranted but
                                  Salamander (Eurycea        Precluded.
                                  tonkawae) as Endangered
                                  With Critical Habitat.
1/08/2008......................  90-Day Finding on a        Notice of 90-day      73 FR 1312-1313.
                                  Petition To List the       Petition Finding,
                                  Pygmy Rabbit               Substantial.
                                  (Brachylagus idahoensis)
                                  as Threatened or
                                  Endangered.
1/10/2008......................  90-Day Finding on          Notice of 90-day      73 FR 1855-1861.
                                  Petition To List the       Petition Finding,
                                  Amargosa River             Substantial.
                                  Population of the Mojave
                                  Fringe-Toed Lizard (Uma
                                  scoparia) as Threatened
                                  or Endangered With
                                  Critical Habitat.
1/24/2008......................  12-Month Finding on a      Notice of 12-month    73 FR 4379-4418.
                                  Petition To List the       Petition Finding,
                                  Siskiyou Mountains         Not Warranted.
                                  Salamander (Plethodon
                                  stormi) and Scott Bar
                                  Salamander (Plethodon
                                  asupak) as Threatened or
                                  Endangered.
2/05/2008......................  12-Month Finding on a      Notice of 12-month    73 FR 6660-6684.
                                  Petition To List the       Petition Finding,
                                  Gunnison's Prairie Dog     Warranted.
                                  as Threatened or
                                  Endangered.
2/07/2008......................  12-Month Finding on a      Notice of Review....  73 FR 7236-7237.
                                  Petition To List the
                                  Bonneville Cutthroat
                                  Trout (Oncorhynchus
                                  clarki utah) as
                                  Threatened or Endangered.
2/19/2008......................  Listing Phyllostegia       Proposed Listing,     73 FR 9078-9085.
                                  hispida (No Common Name)   Endangered.
                                  as Endangered Throughout
                                  Its Range.
2/26/2008......................  Initiation of Status       Notice of Review....  73 FR 10218-10219.
                                  Review for the Greater
                                  Sage-Grouse
                                  (Centrocercus
                                  urophasianus) as
                                  Threatened or Endangered.
3/11/2008......................  12-Month Finding on a      Notice of 12-month    73 FR 12929-12941.
                                  Petition To List the       Petition Finding,
                                  North American Wolverine   Not Warranted.
                                  as Endangered or
                                  Threatened.
3/20/2008......................  90-Day Finding on a        Notice of 90-day      73 FR 14950-14955.
                                  Petition To List the       Petition Finding,
                                  U.S. Population of         Substantial.
                                  Coaster Brook Trout
                                  (Salvelinus fontinalis)
                                  as Endangered.
----------------------------------------------------------------------------------------------------------------

    Our expeditious progress also includes work on listing actions, 
which we are funding in FY 2008. These actions are listed below. We are 
conducting work on those actions in the top section of the table under 
a deadline set by a court. Actions in the middle section of the table 
are being conducted to meet statutory timelines, that is, timelines 
required under the Act. Actions in the bottom section of the table are 
high priority listing actions, which include at least one or more 
species with an LPN of 2, available staff resources, and, when 
appropriate, species with a lower priority if they overlap 
geographically or have the same threats as the species with the high 
priority.

         Actions Funded in FY 2008 That Have Yet To Be Completed
------------------------------------------------------------------------
                Species                               Action
------------------------------------------------------------------------
Actions Subject to Court Order/
 Settlement Agreement:
    Bonneville cutthroat trout.........  12-month petition finding
                                          (remand).
    Mexican garter snake...............  12-month petition finding
                                          (remand).
Actions with Statutory Deadlines:
    Polar bear.........................  Final listing determination.

[[Page 27926]]

 
    Phyllostegia hispida...............  Final listing.
    Yellow-billed loon.................  12-month petition finding.
    Black-footed albatross.............  12-month petition finding.
    Mount Charleston blue butterfly....  12-month petition finding.
    Goose Creek milk-vetch.............  12-month petition finding.
    Mojave fringe-toed lizard..........  12-month petition finding.
    White-tailed prairie dog...........  12-month petition finding.
    Pygmy rabbit (rangewide)...........  12-month petition finding.
    Delta smelt (uplisting)............  90-day petition finding.
    Mono Basin sage grouse (vol.         90-day petition finding.
     remand).
    Ashy storm petrel..................  90-day petition finding.
    Longfin smelt--San Fran. Bay         90-day petition finding.
     population.
    Black-tailed prairie dog...........  90-day petition finding.
    Lynx (include New Mexico in          90-day petition finding.
     listing).
    Wyoming pocket gopher..............  90-day petition finding.
    Llanero coqui......................  90-day petition finding.
    Least chub.........................  90-day petition finding.
    American pika......................  90-day petition finding.
    Dusky tree vole....................  90-day petition finding.
    Sacramento Mts. checkerspot          90-day petition finding.
     butterfly.
    Kokanee--Lake Sammamish population.  90-day petition finding.
    206 species........................  90-day petition finding.
    475 Southwestern species...........  90-day petition finding.
High Priority Listing Actions:
    48 Kauai species \1\...............  Proposed listing.
    21 Kauai species...................  Proposed listing.
    11 packages of high-priority         Proposed listing.
     candidate species.
    Flatwoods salamander (taxonomic      Proposed listing.
     revision).
------------------------------------------------------------------------
\1\ Funds used for this listing action were also provided in FY 2007.

    We have endeavored to make our listing actions as efficient and 
timely as possible, given the requirements of the relevant law and 
regulations, and constraints relating to workload and personnel. We are 
continually considering ways to streamline processes or achieve 
economies of scale, such as by batching related actions together. Given 
our limited budget for implementing section 4 of the Act, these actions 
described above collectively constitute expeditious progress.
    We will list the Rio Grande cutthroat trout as threatened or 
endangered when funding is available for discretionary listing actions. 
We intend any listing action for the Rio Grande cutthroat trout to be 
as accurate as possible. Therefore, we will continue to accept 
additional information and comments on the status of and threats to 
this subspecies from all concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this finding. If an emergency situation develops with this 
subspecies that warrants an emergency listing, we will act immediately 
to provide additional protection.

References Cited

    A complete list of all references cited in this document is 
available from the New Mexico Ecological Services Field Office (see 
ADDRESSES section).

Author

    The primary author of this notice is the staff of the Albuquerque 
Ecological Services Field Office, 2105 Osuna Road NE., Albuquerque, NM 
87113.

    Authority: The authority for this action is the Endangered 
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: April 30, 2008.
Kenneth Stansell,
 Director, Fish and Wildlife Service.
 [FR Doc. E8-10182 Filed 5-13-08; 8:45 am]
BILLING CODE 4310-55-P


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