Endangered and Threatened Wildlife and Plants; Reclassification of the Gila Trout (Oncorhynchus gilae, 24750-24764 [05-9121]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 70, Number 90 (Wednesday, May 11, 2005)]
[Proposed Rules]
[Pages 24750-24764]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-9121]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AH57


Endangered and Threatened Wildlife and Plants; Reclassification 
of the Gila Trout (Oncorhynchus gilae) From Endangered To Threatened 
With Regulations

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
reclassify the federally endangered Gila trout (Oncorhynchus gilae) to 
threatened status under the authority of the Endangered Species Act of 
1973, as amended (Act). Based on a review of the species' current 
status, we have determined that reclassification of the Gila trout to 
threatened status is warranted. We are also proposing a special rule 
under section 4(d) of the Act that would apply to Gila trout found in 
New Mexico and Arizona. If finalized, the special rule included in this 
proposal would enable the New Mexico Department of Game and Fish 
(NMDGF) and the Arizona Game and Fish Department (AGFD) to promulgate 
special regulations in collaboration with the Service, allowing 
recreational fishing of Gila trout, beginning on the date that the 
final 4(d) rule becomes effective.

DATES: We will consider all comments on the proposed rule received from 
interested parties by July 15, 2005. We will hold public hearings on 
this proposed rule; we have scheduled the hearings for June 28, 2005 in 
Phoenix, Arizona and on June 29, 2005 in Silver City, New Mexico (see 
Public Hearing in the SUPPLEMENTARY INFORMATION section of this rule 
for dates).

ADDRESSES:

[[Page 24751]]

    1. Send your comments on this proposed rule to the New Mexico 
Ecological Services Field Office, 2105 Osuna Road NE, Albuquerque, New 
Mexico 87113. Written comments may also be sent by facsimile to (505) 
346-2542 or through electronic mail to R2FWE--AL@fws.gov. You may also 
hand-deliver written comments to our New Mexico Ecological Services 
Field Office, at the above address. You may obtain copies of the 
proposed rule and other related documents from the above address or by 
calling (505) 346-2525. The proposed rule is also available from our 
Web site at https://ifw2es.fws.gov/Library/.
    2. The complete file for this proposed rule will be available for 
public inspection, by appointment, during normal business hours at the 
New Mexico Ecological Services Field Office (see ADDRESSES above).
    3. The public hearings will be held in Phoenix, Arizona on June 28, 
2005 and in Silver City, New Mexico on June 29, 2005.

FOR FURTHER INFORMATION CONTACT: Joy Nicholopoulos, State Supervisor, 
New Mexico Ecological Services Field Office (see ADDRESSES above).

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    We intend to make any final action resulting from this proposed 
rule to be as accurate and as effective as possible. Therefore, we are 
soliciting comments from the public, other concerned governmental 
agencies, the scientific community, industry, or any other interested 
party concerning this proposed rule. We particularly seek comments 
concerning:
    1. The reasons why Gila trout should or should not be reclassified 
with a special rule, as provided by section 4 of the Act;
    2. Information concerning angling opportunities that may be 
affected by this action in New Mexico or Arizona and how the special 
rule might affect these uses; and
    3. Comments on how the special rule could further the conservation 
of the Gila trout beyond what we have discussed in this rule.

Background

    The purposes of the Act are to provide a means whereby the 
ecosystems upon which endangered and threatened species depend may be 
conserved and to provide a program for the conservation of those 
species. Species can be listed as threatened and endangered because of 
any of the following factors: (1) The present or threatened 
destruction, modification, or curtailment of its habitat or range, (2) 
overutilization for commercial, recreational, scientific, or 
educational purposes, (3) disease or predation, (4) the inadequacy of 
existing regulatory mechanisms, and (5) other natural or manmade 
factors affecting its continued existence. When we determine that 
protection of the species under the Act is no longer warranted, we take 
steps to remove (delist) the species from the Federal list. If a 
species is listed as endangered, we may reclassify it to threatened 
status as an intermediate step before eventual delisting, if it has met 
the criteria for downlisting to threatened; however, reclassification 
to threatened status is not required in order to delist.
    Section 3 of the Act defines terms that are relevant to this 
proposal. An endangered species is any species that is in danger of 
extinction throughout all or a significant portion of its range. A 
threatened species is any species that is likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range. A species includes any subspecies of 
fish or wildlife or plants, and any distinct population segment of any 
species of vertebrate fish or wildlife that interbreeds when mature.

Previous Federal Action

    The Gila trout was originally recognized as endangered under the 
Federal Endangered Species Preservation Act of 1966 (32 FR 4001), and 
Federal designation of the species as endangered continued under the 
Act (1973). In 1987, the Service proposed to reclassify the Gila trout 
as threatened (October 6, 1987, 52 FR 37424). However, we withdrew our 
proposal for reclassification in 1991 (September 12, 1991) (see 
``Recovery Plans and Accomplishments'' section below for further 
information). On November 11, 1996, Mr. Gerald Burton submitted a 
petition to us to downlist the species from endangered to threatened. 
We acknowledged receipt of the petition by letter on January 13, 1997. 
This proposed rule constitutes our 90-day finding and 12-month finding 
on the November 11, 1996, petition.

Systematics

    The Gila trout is a member of the salmon and trout family 
(Salmonidae). Gila trout was not formally described until 1950, using 
fish collected in Main Diamond Creek in 1939 (Miller 1950). It is most 
closely related to Apache trout (Oncorhynchus apache), which is endemic 
to the upper Salt and Little Colorado River drainages in east-central 
Arizona. Gila trout and Apache trout are more closely related to 
rainbow trout (O. mykiss) than to cutthroat trout (O. clarki), 
suggesting that Gila and Apache trouts were derived from an ancestral 
form that also gave rise to rainbow trout (Behnke 1992; Dowling and 
Childs 1992; Utter and Allendorf 1994; Nielsen et al. 1998; Riddle et 
al. 1998).

Physical Description

    The Gila trout is readily identified by its iridescent gold sides 
that blend to a darker shade of copper on the opercles (gill covers). 
Spots on the body are small and profuse, generally occurring above the 
lateral line and extending onto the head, dorsal (back, top) fin, and 
caudal (tail) fin. Spots are irregularly shaped on the sides and 
increase in size on the back. On the dorsal surface of the body, spots 
may be as large as the pupil of the fish eye and are rounded. A few 
scattered spots are sometimes present on the anal fin, and the adipose 
fin (fleshy fin located behind dorsal fin) is typically large and well-
spotted. Dorsal, pelvic, and anal fins have a white to yellowish tip 
that may extend along the leading edge of the pelvic fins. A faint, 
salmon-pink band is present on adults, particularly during spawning 
season when the normally white belly may be streaked yellow or reddish 
orange. A yellow cutthroat mark is present on most mature specimens. 
Parr marks (diffuse splotches on the sides of body, usually seen on 
young trout) are commonly retained by adults, although they may be 
faint or absent (Miller 1950; David 1976).
    Characteristics that distinguish Gila trout from other co-
occurring, non-native trout include the golden coloration of the body, 
parr marks, and fine, profuse spots above the lateral line. These 
characters differentiate Gila trout from rainbow, brown (Salmo trutta), 
and cutthroat trouts. Roundtail chub (Gila robusta) are locally 
confused with Gila trout (Minckley 1973). The two species share a 
similar distribution, although roundtail chub typically occurs at lower 
elevations than Gila trout currently occupies. The two species may be 
confused partly because roundtail chub are occasionally caught by 
anglers fishing where both species occur together. The roundtail chub, 
a minnow (family Cyprinidae) whose adult size is similar to Gila 
trout's, differs from Gila trout (family Salmonidae) by its body shape 
and coloration. The roundtail chub lacks an adipose fin and has a 
narrow caudal peduncle (the segment of the body to which the tail fin 
is attached). Also, roundtail chub lack parr marks, golden coloration, 
yellow cutthroat marks, and

[[Page 24752]]

salmon-pink band found on Gila trout. Roundtail chub are typically a 
mottled olive or dark silver color above the lateral line, and body 
coloration lightens to a light silvery hue below the lateral line 
(Sublette et al. 1990).

Distribution and Threats

    The extent of the historical distribution of the Gila trout is not 
known with certainty (Behnke 2002). It is known to be native to higher 
elevation streams in portions of the Gila River drainage, New Mexico. 
According to anecdotal reports, in 1896 Gila trout were found in the 
Gila River drainage, New Mexico, from the headwaters downstream to a 
box canyon, about 11.3 km (7 mi) northeast of Cliff, New Mexico (Miller 
1950). By 1915, the downstream distribution of Gila trout in the Gila 
River had receded upstream to Sapillo Creek, a distance of 
approximately 25 km (15 mi) (Miller 1950). By 1950, water temperature 
in the Gila River at Sapillo Creek was considered too warm to support 
any trout species (Miller 1950). The earliest documented collections of 
Gila trout in the upper Gila River drainage were in 1939, from Main 
Diamond Creek (Miller 1950). New populations were sporadically found 
until 1992 when Gila trout were discovered in Whiskey Creek, a 
tributary to the upper West Fork Gila River (Service 2003).
    Miller (1950) documented changes in suitability of habitats for 
Gila trout in the upper Gila drainage. Unregulated livestock grazing 
and logging likely contributed to habitat modifications noted by Miller 
(1950). The historical occurrence of intensive grazing and resulting 
effects on the land (e.g., increased sedimentation by removal of 
riparian vegetation and increased runoff rates due to soil compaction) 
are indicated in published reports dating back to the early 1900s 
(Rixon 1905; Rich 1911; Duce 1918; Leopold 1921; Leopold 1924). Logging 
activities also likely caused major changes in watershed 
characteristics and stream morphology. Rixon (1905) reported the 
occurrence of small timber mills in numerous canyons of the upper Gila 
River drainage. Early logging efforts were concentrated along canyon 
bottoms, often with perennial streams. Tree removal along perennial 
streams within the historical range of Gila trout likely altered water 
temperature regimes, sediment loading, bank stability, and availability 
of large woody debris (Chamberlin et al. 1991).
    When the Gila trout was listed as endangered, it was thought that 
its range had been reduced to five streams within the Gila National 
Forest, New Mexico: Iron, McKenna, Spruce, Main Diamond, and South 
Diamond. In 1998, it was determined that the McKenna and Iron Creek 
populations had hybridized with rainbow trout and therefore, did not 
contribute to the recovery of the species because they are not pure 
(Leary and Allendorf 1998; Service 2003). In 1992, another original 
pure population (i.e., relict population) of Gila trout was discovered 
in Whiskey Creek (Leary and Allendorf 1998). Consequently, there are 
four confirmed original pure populations known today. Reasons for 
listing the Gila trout as endangered included hybridization, 
competition, and/or predation by non-native rainbow, cutthroat, and 
brown trout, and habitat degradation.
    Occurrence of Gila trout in tributaries to the Gila River in 
Arizona is less certain, although these streams harbored a native 
trout. Native trout occurred in the Eagle Creek drainage, a tributary 
of the Gila River in Arizona located west of the San Francisco River 
drainage (Minckley 1973; Kynard 1976). The identity of this native 
trout, now lost through hybridization with rainbow trout, is uncertain 
(Marsh et al. 1990). Native trout were reported from Oak Creek, a 
tributary to the Verde River, before the turn of the century (Miller 
1950). Four specimens collected from Oak Creek before 1890 were 
ascribed to Gila trout (Miller 1950; Minckley 1973). Native trout were 
also reported from West Clear Creek, another Verde River tributary 
(Miller 1950). Trout collected in 1975 from Sycamore Creek, a tributary 
of Agua Fria, were reported to be Gila x rainbow trout hybrids. 
However, this determination was based solely on examination of spotting 
pattern (Behnke and Zarn 1976). Unfortunately, no pure Gila trout are 
extant from Arizona tributaries to the Gila River and scientists are 
unable to make a clear determination of the identity of the four 
remaining preserved specimens that were collected from Oak Creek 
(Miller 1972).

Habitat Characteristics

    Nursery and rearing habitats are areas used by larval and juvenile 
Gila trout. Although no studies have been done on habitat use by these 
life stages of Gila trout, generalizations can be made based on 
characteristics of related trout species. Suitable nursery habitat for 
trout includes areas with slow current velocity such as stream margins, 
seeps, shallow bars, and side channels (Behnke 1992). Low flows during 
emergence from the egg and early growth of larval trout may result in 
strong year classes (young fish are not displaced downstream) (Behnke 
1992), as may constant, elevated flows during summer (improved water 
quality) (Service 2003). Absence of predation by non-native trout, 
particularly brown trout, is another essential element of nursery and 
rearing habitat.
    Subadult and adult habitats are defined as areas suitable for 
survival and growth of these life stages. Subadults are sexually 
immature individuals, generally less than 150 millimeters (mm) (6 
inches (in)) total length and adults are sexually mature individuals 
typically greater than 150 mm (6 in) total length (Propst and Stefferud 
1997). Subadult Gila trout occur primarily in riffles (shallow water 
flowing over cobbles), riffle-runs, and runs, while adults are found 
mainly in pools (Rinne 1978). Cover (large woody debris, undercut 
banks, boulders, deep water, and overhanging woody and herbaceous 
vegetation) is an important component of subadult and adult habitat 
(Stefferud 1994). The quantity and quality of adult habitat typically 
limits the trout population biomass (Behnke 1992). Essential elements 
of subadult and adult habitat relate principally to channel dimensions, 
cover, and hydrologic variability. Absence of competition with non-
native trouts (brown and rainbow) for foraging habitat is also an 
essential element of subadult and adult habitat.
    Variation in stream flow is a major factor affecting subadult and 
adult population size (McHenry 1986, Turner 1989, Propst and Stefferud 
1997). In particular, high flow events may cause marked decrease in 
population size. These events result in short-term, radical changes in 
habitat conditions, primarily in flow velocity. Because most streams 
occupied by Gila trout have relatively narrow floodplains, the forces 
associated with high flow events are concentrated in and immediately 
adjacent to the bankfull channel. High stream flow velocities cause 
channel scouring and displacement of fish downstream, often into 
unsuitable habitats (Rinne 1982).
    Overwintering habitat is defined as areas that afford shelter 
during periods of low water temperature, generally from November 
through February. Rinne (1981) and Propst and Stefferud (1997) 
indicated the importance of pool habitat for overwinter survival of 
Gila trout. Essential elements of overwintering habitat are deep water 
with low current velocity and protective cover (Behnke 1992). These 
elements are important because small streams can freeze, but the 
presence of deep pools provides areas that do not freeze. Trout are 
typically more sluggish in the winter and cover is important to protect 
them

[[Page 24753]]

from predators. Barriers to fish movement (e.g., waterfalls, dry stream 
bed) that prevent fish from accessing overwintering habitat may impact 
populations of Gila trout. Gila trout are now restricted to small 
headwater streams that typically have fewer deep pools and less 
suitable overwintering habitat than do larger streams (Harig and Fausch 
2002).

Life History

    Spawning occurs mainly in April (Rinne 1980) when temperatures are 
6 to 8[deg]C (43 to 46[deg]F); however, day length may also be an 
important cue. Stream flow is apparently of secondary importance in 
triggering spawning activity (Rinne 1980). Young fish less than 25 mm 
(1.0 in) in length emerge from gravel nests 56 to 70 days after egg 
deposition (Rinne 1980). By the end of their first summer, young attain 
a total length of 70 to 90 mm (2.7 to 3.5 in) at lower elevation 
streams and 40 to 50 mm (1.6 to 2.0 in) at higher elevation sites 
(Rinne 1980; Turner 1986). Growth rates are variable, but Gila trout 
generally reach 180 to 220 mm (7.1 to 8.7 in) total length by the end 
of the third growing season in all but higher elevation streams. On 
average, for every 100 eggs that hatch, only two fish will survive to 
become adults (Brown et al. 2001).
    Females reach maturity at age 2 to 4 at a minimum length of about 
130 mm (5 in) (Nankervis 1988, Propst and Stefferud 1997). Males 
typically reach maturity at age 2 or 3. Most Gila trout live to about 
age 5 (Turner 1986), with a maximum age of 9 reported by Nankervis 
(1988). Thus, the majority of female Gila trout only spawn once and 
most males only spawn two or three times.
    Aquatic insects are the primary food of Gila trout. Regan (1966) 
reported that adult flies, caddisfly larvae, mayfly nymphs, and aquatic 
beetles were the most abundant food items in the stomachs of Gila trout 
in Main Diamond Creek. There was little variation in food habits over 
the range of size classes sampled (47 to 168 mm (1.8 to 6.6 in) total 
length). Gila trout diet shifted seasonally as the relative abundance 
of various prey changed. Insect taxa consumed by Gila trout were also 
common in stomach contents of non-native trout species in the Gila 
River drainage, indicating the potential for interspecific competition. 
Hanson (1971) noted that Gila trout established a feeding hierarchy in 
pools during a low flow period in Main Diamond Creek. Larger fish 
aggressively guarded their feeding stations and chased away smaller 
fish. Large Gila trout occasionally consume speckled dace and may also 
cannibalize smaller Gila trout (Van Eimeren 1988; Propst and Stefferud 
1997).
    Adult Gila trout are typically sedentary and movement is influenced 
by population density and territoriality (Rinne 1982). Although 
individual fish may move considerable distances (e.g., over 1.5 km (0.9 
mi)), Rinne (1982) found that after eight months, 75 percent of tagged 
fish were less than 100 m (328 ft) from their release sites in Main 
Diamond, South Diamond, and McKnight Creeks. Gila trout showed a 
tendency to move upstream in South Diamond Creek, possibly to perennial 
reaches with suitable pool habitat in response to low summer discharge. 
Downstream movement in Main Diamond and McKnight Creeks involved 
primarily smaller fish and probably occurred because of nocturnal 
migrations (nighttime dispersal) or displacement downstream during 
flooding (Rinne 1982). High density of log structures in Main Diamond 
Creek appeared to reduce mobility of Gila trout in that stream (Rinne 
1982).
    Factors affecting population size and dynamics of Gila trout are 
not well understood. Inferences about factors that control population 
size have been made from analysis of time-series data (Turner and 
McHenry 1985, Turner 1989, Propst and Stefferud 1997). Hydrologic 
variability appears to be most important in regulating population size 
of Gila trout in many of the streams occupied by the species (e.g., 
Regan 1966, Mello and Turner 1980, McHenry 1986, Turner 1989, Brown et 
al. 2001). Gila trout populations typically have high densities during 
relatively stable flow periods (Platts and McHenry 1988). The overall 
importance of environmental factors, specifically drought and flooding, 
that can occur following a fire due to a loss of vegetation, are 
critical factors in determining persistence of Gila trout populations. 
Examples of the effects of severe wildfires and subsequent floods and 
ash flows are the elimination of the Gila trout populations from Main 
Diamond Creek (1989) and South Diamond Creek (1995).

Recovery Plans and Accomplishments

    The original recovery plan for Gila trout was completed in 1979. 
The main objective of this recovery plan was ``To improve the status of 
Gila trout to the point that its survival is secured and viable 
populations of all morphotypes are maintained in the wild'' (Service 
1979). The Gila Trout Recovery Plan was revised in 1984 with the same 
objective as the original plan. Downlisting criteria in the plan stated 
that ``The species could be considered for downlisting from its present 
endangered status to a threatened status when survival of the four 
original ancestral populations is secured and when all morphotypes are 
successfully replicated or their status otherwise appreciably 
improved'' (Service 1984). Replication involves either moving 
individuals from a successfully reproducing original pure or replicated 
population or taking hatchery-propagated fish and releasing them into a 
renovated stream. In 1987, we proposed that Gila trout be reclassified 
from endangered to threatened with a special rule to allow sport 
fishing (52 FR 37424). At that time, Gila trout populations were deemed 
sufficiently secure to meet criteria for reclassification to threatened 
as identified in the Plan (52 FR 37424). However, the proposed rule to 
downlist Gila trout was withdrawn in 1991 (September 12, 1991, 56 FR 
46400) because:
    1. Severe flooding in 1988 reduced the Gila trout populations in 
McKnight Creek by about 80 percent;
    2. Wild fires in 1989 eliminated Gila trout from Main Diamond Creek 
and all of the South Diamond drainage except Burnt Canyon, a small 
headwater stream;
    3. Propagation activities at hatcheries had not proceeded as 
planned and fish were not available to replenish wild stocks; and
    4. Brown trout, a predator, was present in Iron Creek, which at the 
time was thought to harbor one of the original pure populations of Gila 
trout.
    The Gila Trout Recovery Plan was revised in 1993 to incorporate new 
information about ecology of the species and recovery methods. Criteria 
for downlisting remained essentially the same as in the 1984 revision 
but were more specific. The 1993 plan specified that downlisting would 
be considered ``when all known indigenous lineages are replicated in 
the wild'' and when Gila trout were ``established in a sufficient 
number of drainages such that no natural or human-caused event may 
eliminate a lineage.'' The recovery plan was revised again in 2003 
(Service 2003). The criteria for downlisting in the 2003 Recovery Plan 
include the following: (1) The four known non-hybridized indigenous 
lineages are protected and replicated in the wild in at least 85 km (53 
mi) of streams; (2) each known non-hybridized lineage is replicated in 
a stream geographically separate from its remnant population such that 
no natural or human-caused event may eliminate a lineage; and (3)

[[Page 24754]]

an Emergency Evacuation Procedures Plan for Gila Trout (Emergency Plan) 
to address wildfire impacts and discovery of non-native salmonid 
invasion in Gila trout streams has been developed and implemented.
    Today three of the four original pure populations (Main Diamond, 
South Diamond, and Spruce Creeks) are replicated at least once. The 
Service believes the three replicated populations are secure and the 
viability of the Gila trout is sufficiently protected through these 
three populations. The species is no longer in danger of extinction. 
Whiskey Creek, the fourth pure population, is not replicated. The 
Service believes that a small population of Gila trout remains in 
Whiskey Creek and that it may be possible to replicate the Whiskey 
Creek population in the future. Work will continue to conserve the 
Whiskey Creek lineage, if possible. Whiskey Creek is considered a harsh 
environment, and the Gila trout population there has been in a tenuous 
situation. A broodstock management plan and an Emergency Plan have been 
completed (Kincaid and Reisenbichler 2002; Service 2004). Recovery 
actions have included chemically treating streams within the historic 
range of the species to remove non-native fish species, removing non-
native trout by electrofishing, and constructing physical barriers to 
prevent movement of non-natives into renovated reaches (Service 2003).
    Surveys of the 12 existing populations indicate that the recovery 
efforts to remove non-native fish and prevent their return to the 
renovated areas have been successful (Service 2003). Replicated 
populations in New Mexico are successfully reproducing, indicating that 
suitable spawning and rearing habitats are available. Replicated 
populations in Arizona exist in Raspberry and Dude Creeks. Young of the 
year were planted in Raspberry Creek in Arizona in 2000. In 2004, Gila 
trout in Raspberry Creek were found in mixed size classes, indicating 
that the fish spawned and successfully recruited. Although some fish 
were removed from Raspberry Creek due to the threat of wildfire, some 
of these fish were restocked in November 2004 into the uppermost 
portions of Raspberry Creek, which survived the impacts caused by the 
fire and which still support Gila trout. The status of the population 
at Raspberry Creek will be reassessed in 2005. Factors limiting 
reproduction in Dude Creek in Arizona are not known.
    Overall, there has been an increase in the total wild population of 
Gila trout. In 1992, the wild populations of Gila trout were estimated 
to be less than 10,000 fish greater than age 1. In 2001, the population 
in New Mexico was estimated to be 37,000 fish (Brown et al. 2001). As 
noted above, Gila trout were more recently replicated in Arizona; as 
such, we do not have estimated numbers of fish at this time. The stream 
renovation and transplantation efforts have been accomplished jointly 
by the Service, Forest Service, NMDGF, AGFD, and New Mexico State 
University. Original pure populations and their replicates are 
summarized in Table 1.

      Table 1.--Summary and Status of Streams Inhabited by Gila Trout as of January 2001 (Original Pure Population (i.e., Relict) Lineages in Bold)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                     km (mi) of
    State               County                       Stream name                            Drainage                   stream              Origin
                                                                                                                      inhabited
--------------------------------------------------------------------------------------------------------------------------------------------------------
NM..........  Sierra...................  Main Diamond Creek.................  East Fork Gila River...............  6.1 (3.8)       Relict Lineage
                                                                                                                                    Eliminated in 1989,
                                                                                                                                    re-established in
                                                                                                                                    1994.
NM..........  Grant....................  McKnight Creek.....................  Mimbres River......................  8.5 (5.3)       Replicate of Main
                                                                                                                                    Diamond, est. 1970.
NM..........  Grant....................  Black Canyon.......................  East Fork Gila River...............  18.2 (11.3)     Replicate of Main
                                                                                                                                    Diamond, est. 1998.
NM..........  Catron...................  Lower Little Creek.................  West Fork Gila River...............  6.0 (3.7)       Replicate of Main
                                                                                                                                    Diamond, est. 2000.
NM..........  Catron...................  Upper White Creek..................  West Fork Gila River...............  8.8 (5.5)       Replicate of Main
                                                                                                                                    Diamond, est. 2000.
NM..........  Sierra...................  South Diamond Creek\1\.............  East Fork Gila River...............  6.7 (4.2)       Relict Lineage
                                                                                                                                    Eliminated in 1995,
                                                                                                                                    re-established in
                                                                                                                                    1997.
NM..........  Catron (Grant)...........  Mogollon Creek\2\..................  Gila River.........................  28.8 (17.9)     Replicate of South
                                                                                                                                    Diamond Creek, est.
                                                                                                                                    1987.
NM..........  Catron...................  Spruce Creek.......................  San Francisco River................  3.7 (2.3)       Relict Lineage
NM..........  Catron...................  Big Dry Creek......................  San Francisco River................  1.9 (1.2)       Replicate of Spruce
                                                                                                                                    Creek, est. 1985.
AZ..........  Gila.....................  Dude Creek.........................  Verde River........................  3.2 (2.0)       Replicate of Spruce
                                                                                                                                    Creek, est. 1999.
AZ..........  Greenlee.................  Raspberry Creek....................  Blue River.........................  6.0 (3.7)       Replicate of Spruce
                                                                                                                                    Creek, est. 2000.
NM..........  Catron...................  Whiskey Creek......................  West Fork Gila River...............  2.6 (1.6)       Relict Lineage
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ South Diamond Creek includes Burnt Canyon.
\2\ Mogollon Creek includes Trail Canyon, Woodrow Canyon, Corral Canyon, and South Fork Mogollon Creek. Portions of the drainage are in Grant County,
  New Mexico.

    Three of the four original pure population lineages are currently 
protected and replicated in 100 km (62 mi) of stream, each replicate is 
geographically separate from its original pure population, and an 
Emergency Plan has been developed and implemented. The Emergency Plan 
addresses wildfire-related impacts and discovery of non-native salmonid 
invasions (Service 2004). In 2002, the Emergency Plan (Service 2004) 
was implemented during the Cub Fire to evacuate fish from Whiskey Creek 
(Brooks 2002), and in 2003 the plan was implemented during the Dry 
Lakes Fire to remove fish from Mogollon Creek (J. Brooks, U.S. Fish and 
Wildlife Service, in litt. 2003b).

Summary of Factors Affecting the Species

    Section 4 of the Act and regulations issued to implement the 
listing provisions of the Act (50 CFR Part 424) set forth the 
procedures for listing, reclassifying, and delisting species. Species 
may be listed as threatened or endangered if one or more of the five 
factors described in section 4(a)(1) of the Act threaten the continued 
existence of

[[Page 24755]]

the species. A species may be reclassified, according to 50 CFR 
424.11(c), if the best scientific and commercial data available 
substantiate that the species' status at which it is listed is no 
longer correct. This analysis must be based upon the five categories of 
threats specified in section 4(a)(1).
    For species that are already listed as threatened or endangered, 
this analysis of threats is primarily an evaluation of the threats that 
could potentially affect the species in the foreseeable future 
following the delisting or downlisting and the removal or reduction of 
the Act's protections. Our evaluation of the future threats to the Gila 
trout that would occur after reduction of the protections of the Act is 
partially based on the protection provided by the Gila and Aldo Leopold 
Wilderness areas, the Emergency Plan, the broodstock management plan, 
and limitations on take that would be determined by the States in 
collaboration with us.
    After a thorough review of all available information and an 
evaluation of the five factors specified in section 4(a)(1) of the Act, 
we are proposing to reclassify the Gila trout as threatened, with a 
special rule allowing for recreational fishing, due to partial 
recovery. Discussion of the five listing factors and their application 
to recovery of the Gila trout are as follows:

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

    In the past, Gila trout populations were threatened by habitat 
degradation and watershed disturbances (52 FR 37424). These factors 
compounded the threats posed by non-native salmonids (see Factors C and 
E below for discussions on non-native salmonids). We discuss habitat 
degradation from livestock grazing, timber harvest, and wildfires 
below.
Livestock Grazing
    Intensive livestock grazing has been shown to increase soil 
compaction, decrease infiltration rates, increase runoff, change 
vegetative species composition, decrease riparian vegetation, increase 
stream sedimentation, increase stream water temperature, decrease fish 
populations, and change channel form (Meehan and Platts 1978; Kaufman 
and Kruger 1984; Schulz and Leininger 1990; Platts 1991; Fleischner 
1994; Ohmart 1996). Although direct impacts to the riparian zone and 
stream can be the most obvious sign of intensive livestock grazing, 
upland watershed condition is also important because changes in soil 
compaction, percent cover, and vegetative type influence the timing and 
amount of water delivered to stream channels (Platts 1991). Increased 
soil compaction, decreased vegetative cover, and a decrease in 
grasslands lead to faster delivery of water to stream channels, 
increased peak flows, and lower summer base flow (Platts 1991; Ohmart 
1996; Belsky and Blumenthal 1997). As a consequence, streams are more 
likely to experience flood events during monsoons (water runs off 
quickly instead of soaking into the ground) that negatively affect the 
riparian and aquatic habitats and are more likely to become 
intermittent or dry in September and October (groundwater recharge is 
less when water runs off quickly) (Platts 1991; Ohmart 1996).
    Improper livestock grazing practices degrade riparian and aquatic 
habitats, likely resulting in decreased production of trout (Platts 
1991). Livestock affect riparian vegetation directly by eating grasses, 
shrubs, and trees, by trampling the vegetation, and by compacting the 
soil. Riparian vegetation benefits streams and trout by providing 
insulation (cooler summer water temperatures, warmer winter water 
temperatures), by filtering sediments so that they do not enter the 
stream (sediment clogs spawning gravel and reduces the survival of 
salmonid eggs), by providing a source of nutrients to the stream from 
leaf litter (increases stream productivity), and by providing root 
wads, large woody debris, and small woody debris to the stream 
(provides cover for the fish) (Kauffman and Krueger 1984; Platts 1991; 
Ohmart 1996). Poor livestock grazing practices can increase 
sedimentation through trampling of the steam banks (loss of vegetative 
cover), by removal of riparian vegetation (filters sediment), and 
through soil compaction (decreases infiltration rates, increases 
runoff, causes increased erosion). Sediment is detrimental to trout 
because it decreases the survival of their eggs (Bjornn and Reiser 
1991), and because of its negative impact on aquatic invertebrates, a 
food source for trout (Wiederholm 1984).
    In the late 1800s and early 1900s, livestock grazing was 
uncontrolled and unmanaged over many of the watersheds that contain 
Gila trout, and much of the landscape was denuded of vegetation (Rixon 
1905; Duce 1918; Leopold 1921; Leopold 1924; Ohmart 1996). Livestock 
grazing is more carefully managed now, which has resulted in less 
impact to streams occupied by Gila trout. Improved grazing management 
practices (e.g., fencing) have reduced livestock access to streams. Six 
of the 12 streams currently occupied by Gila trout are within Forest 
Service grazing allotments. However, as described below, on creeks 
occupied by Gila trout, grazing has either been suspended or cattle are 
typically excluded.
    Mogollon Creek is within the Rain Creek/74 Mountain Allotment. This 
allotment receives only winter use, and much of the riparian habitat is 
inaccessible to livestock. Riparian vegetation along Mogollon Creek is 
in good condition (A. Telles, U.S. Forest Service, Gila National 
Forest, in litt. 2003c). Main Diamond Creek and the adjacent riparian 
zone, located in the South Fork Allotment, are excluded from grazing. 
The Forest Service is implementing a fencing project along Turkey Run 
Creek to prevent livestock trespass into Main Diamond Creek (A. Telles, 
U.S. Forest Service, Gila National Forest, in litt. 2003c).
    South Diamond Creek and Black Canyon are within the Diamond Bar 
Allotment, where grazing was suspended in 1996. This has resulted in 
marked improvements in the condition of riparian and aquatic habitat in 
these areas (A. Telles, U.S. Forest Service, Gila National Forest, in 
litt. 2003c).
    In Arizona on the Apache-Sitgreaves National Forest, Raspberry 
Creek, which is located in the Blue Range Primitive Area, includes two 
grazing allotments, Strayhorse and Raspberry. The Strayhouse Allotment 
includes about 75 percent of the watershed above the fish barrier. The 
allotment was evaluated in July 1998, and determined to be in ``Proper 
Functioning Condition'' (D. Bills, U.S. Fish and Wildlife Service, in 
litt. 2003d). It has a well-developed riparian plant community and no 
adverse impacts from ongoing livestock grazing (Service 2000). 
Evaluation of the Raspberry Allotment occurred twice in 1998 and 
concluded that the allotment was ``Functional--At Risk'' and in a 
``Downward'' trend (Service 2000). The report noted an incised channel 
(eroded downward), and concluded that upland watershed conditions were 
contributing to the riparian degradation. Significant changes were made 
to the Raspberry Allotment in 2000 (Service 2000). Specifically, the 
Forest Service required a reduction in livestock numbers to 46 cattle 
from November 1 to June 14 (or removal of cattle prior to June 14 if 
utilization standards are reached). Prior to this, 225 cattle were 
permitted on the Allotment yearlong and 160 cattle were permitted from 
January 1 to May 15.
    Dude Creek, on the Tonto National Forest, is within the East Verde 
Pasture of the Cross V Allotment. Current management techniques are 
designed to protect the stream banks and riparian

[[Page 24756]]

vegetation, thereby reducing sedimentation and increasing river 
insulation (and thereby maintaining cooler summer and warmer winter 
water temperatures).
Timber Harvest
    Logging activities in the early to mid 1900s likely caused major 
changes in watershed characteristics and stream morphology (Chamberlin 
et al. 1991). Rixon (1905) reported the occurrence of small timber 
mills in numerous canyons of the upper Gila River drainage. Early 
logging efforts were concentrated along canyon bottoms, often with 
perennial streams. Tree removal along perennial streams within the 
historical range of Gila trout likely altered water temperature 
regimes, sediment loading, bank stability, and availability of large 
woody debris (Chamberlin et al. 1991). Nine of 10 populations in New 
Mexico exist in the Aldo Leopold Wilderness or Gila Wilderness. Of the 
two populations in Arizona, Raspberry Creek occurs in the Blue Range 
Primitive Area. Timber harvest is not allowed in wilderness or 
primitive areas. There are no plans for timber harvest near the other 
streams that have Gila trout (A. Telles, U.S. Forest Service, Gila 
National Forest, in litt. 2003c). If timber harvest were to be proposed 
in the future, in the two areas located outside of a wilderness or 
primitive area, the Forest Service would need to consider the effects 
of the proposed action under section 7 of the Act.
Fire
    High-severity wildfires, and subsequent floods and ash flows, 
caused the extirpation of seven populations of Gila trout since 1989: 
Main Diamond (1989), South Diamond (1995), Burnt Canyon (1995), Trail 
Canyon (1996), Woodrow Canyon (1996), Sacaton Creek (1996), Upper 
Little Creek (2003) (Propst et al. 1992; Brown et al. 2001; J. Brooks, 
Service, pers. comm. 2003). Lesser impacts were experienced in 2002 
when ash flows following the Cub Fire affected the lower reach of 
Whiskey Creek. However, lower Whiskey Creek is frequently intermittent 
and typically contains few fish (Brooks 2002). Upper Whiskey Creek, 
where the majority of the fish occur, was not affected by the Cub Fire. 
The Cub Fire also impacted the upper West Fork Gila and may have 
eliminated non-native trout from the watershed upstream of Turkey 
Feather Creek (Brooks 2002). In 2003, fire retardant was dropped on 
Black Canyon, affecting approximately 200 m (218 yards) of stream (J. 
Monzingo, U.S. Forest Service, Gila National Forest, in litt. 2003e). 
Although some Gila trout were killed, the number of mortalities is 
unknown (J. Monzingo, U.S. Forest Service, Gila National Forest, in 
litt. 2003e) because dead fish were carried by the current out of the 
area by the time fire crews arrived. However, a week after the 
retardant drop, live Gila trout were observed about 400 m (438 yards) 
below the drop site (J. Monzingo, U.S. Forest Service, Gila National 
Forest, in litt. 2003e).
    Severe wildfires capable of extirpating or decimating fish 
populations are a relatively recent phenomenon, and result from the 
cumulative effects of historical or overly intensive grazing (can 
result in the removal of fine fuels needed to carry fire) and fire 
suppression (Madany and West 1983; Savage and Swetnam 1990; Swetnam 
1990; Touchan et al. 1995; Swetnam and Baisan 1996; Belsky and 
Blumenthal 1997; Gresswell 1999), as well as the failure to use good 
forestry management practices to reduce fuel loads. Historic wildfires 
were primarily cool-burning understory fires with return intervals of 
3-7 years in ponderosa pine (Swetnam and Dieterich 1985). Cooper (1960) 
concluded that prior to the 1950s, crown fires were extremely rare or 
nonexistent in the region. In 2003, over 200,000 acres burned in the 
Gila NF (S. Gonzales, U.S. Fish and Wildlife Service, in litt. 2004). 
The watersheds of Little Creek, Black Canyon, White Creek, and Mogollon 
Creek were affected. Because Gila trout are found primarily in 
isolated, small streams, avoidance of ash flows is impossible and 
opportunities for natural recolonization usually do not exist (Brown et 
al. 2001). Persistence of Gila trout in streams affected by fire and 
subsequent ash flows is problematic. In some instances, evacuation of 
Gila trout from streams in watersheds that have burned is necessary 
(Service 2004).
    Effects of fire may be direct and immediate or indirect and 
sustained over time (Gresswell 1999). The cause of direct fire-related 
fish mortalities has not been clearly established (Gresswell 1999). 
Fatalities are most likely during intense fires in small, headwater 
streams with low flows (less insulation and less water for dilution). 
In these situations, water temperatures can become elevated or changes 
in pH may cause immediate death (Cushing and Olson 1963). Spencer and 
Hauer (1991) documented 40-fold increases in ammonium concentrations 
during an intense fire in Montana. Ammonia is very toxic to fish 
(Wetzel 1975). The inadvertent dropping of fire retardant in streams is 
another source of direct mortality during fires (J. Monzingo, U.S. 
Forest Service, Gila National Forest, in litt. 2003e).
    Indirect effects of fire include ash and debris flows, increases in 
water temperature, increased nutrient inputs, and sedimentation 
(Swanston 1991; Bozek and Young 1994; Gresswell 1999). Ash and debris 
flows can cause mortality months after fires occur when barren soils 
are eroded during monsoonal rain storms (Bozek and Young 1994; Brown et 
al. 2001). Fish suffocate when their gills are coated with fine 
particulate matter, they can be physically injured by rocks and debris, 
or they can be displaced downstream below impassable barriers into 
habitat occupied by non-native trout. Ash and debris flows or severe 
flash flooding can also decimate aquatic invertebrate populations that 
the fish depend on for food (Molles 1985; Rinne 1996; Lytle 2000). In 
larger streams, refugia are typically available where fish can 
withstand the short-term adverse conditions; small headwater streams 
are usually more confined, concentrating the force of water and debris 
(Pearsons et al. 1992; Brown et al. 2001).
    Increases in water temperature occur when the riparian canopy is 
eliminated by fire and the stream is directly exposed to the sun. After 
fires in Yellowstone National Park, Minshall et al. (1997) reported 
that maximum water temperatures were significantly higher in headwater 
streams affected by fire than temperatures in reference (unburned) 
streams; these maximum temperatures often exceeded tolerance levels of 
salmonids. Warm water is stressful for salmonids and can lead to 
increases in disease and lowered reproductive potential (Bjornn and 
Reiser 1991). Salmonids need clean, loose gravel for spawning sites 
(Bjornn and Reiser 1991). Ash and fine particulate matter created by 
fire can fill the interstitial spaces between gravel particles and 
eliminate spawning habitat or, depending on the timing, suffocate eggs 
that are in the gravel. Increases in water temperature and 
sedimentation can also impact aquatic invertebrates, changing species 
composition and reducing population numbers (Minshall 1984; Wiederholm 
1984; Roy et al. 2003), consequently affecting the food supply of 
trout.
    As discussed above, in the ``Timber'' and ``Grazing'' sections, we 
have determined that the threats to Gila trout habitat from grazing and 
timber harvest have been greatly reduced over time. It is expected that 
the livestock management practices (e.g., exclusion from riparian 
zones, reduction in numbers, suspension of grazing in some allotments) 
that have been implemented

[[Page 24757]]

will remain in place (A. Telles, U.S. Forest Service, Gila National 
Forest, in litt. 2003c). Additionally, the Forest Service will continue 
to consider the effects of grazing on Gila trout under section 7 of the 
Act. Presently, 9 of the 10 streams that contain Gila trout occur in 
the Aldo Leopold Wilderness Area or the Gila Wilderness within the Gila 
National Forest, New Mexico. Timber harvest, roads, and mechanized 
vehicles are not allowed in wilderness areas, providing further 
protection to the habitat of Gila trout. Dispersed recreation does 
occur in wilderness areas but because of the inaccessibility of most of 
the streams (not near roads, hiking or backpacking is required), 
dispersed recreation has very little impact on the habitat. By 
practice, the NMDGF does not stock non-native trout within wilderness 
areas or above any barrier that protects a population of Gila trout. 
The NMDGF has not stocked non-native fish in wilderness areas for over 
20 years (Mike Sloan, NMDGF, pers. comm. 2004).
    High-severity forest fires remain a threat to isolated populations 
because natural repopulation is not possible. However, populations have 
been reestablished after forest fires (Main Diamond and South Diamond 
Creeks), there is an Emergency Plan (Service 2004) that outlines 
procedures to be taken in case of a high-severity forest fire, and most 
populations are sufficiently disjunct (e.g., separated by mountain 
ridges), thereby ensuring that one fire would not affect all 
populations simultaneously. Additionally, as discussed in this rule, 
fires have occurred in recent times in many areas occupied by Gila 
trout. Thus, the risk of fire in these areas, especially one that would 
affect all populations, is reduced due to an overall reduction in fuel 
loads. Populations may still be extirpated because of forest fires, but 
through management activities (rescue of fish, reestablishment of 
populations, hatchery management) populations can be, and have been, 
reestablished successfully once the habitat recovers.

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

    All stream reaches that contain Gila trout have been closed to 
sport fishing since the fish was listed in 1967. While some illegal 
fishing may take place, we believe that the amount of take is small. 
These are remote high-elevation streams located away from roads and 
difficult to access. NMDGF visits the recovery streams on an annual 
basis and has found limited evidence of illegal fishing activity (e.g., 
fishing tackle has been found on a few occasions). Also, because NMDGF 
makes periodic visits to these streams, we believe their possible 
presence at unpredictable times serves as a deterrent to illegal 
angling activities.
    The special rule (see ``Description of Proposed Special Rule'' 
section below) being proposed with this reclassification would enable 
NMDGF and the AGFD to promulgate special regulations allowing 
recreational fishing of Gila trout in specified waters, not including 
the four relict populations identified in Table 1 above. Any changes to 
the recreational fishing regulations will be made by the States with in 
collaboration with the Service. Management as a recreational species 
will be conducted similar to Apache trout, with angling in both 
recovery and enhancement waters. Enhancement waters are those managed 
solely for recreational purposes. Recreational management for Gila 
trout will be consistent with the goals of the recovery plan for the 
species (Service 2003). It is anticipated that implementation of the 
special rule will benefit the Gila trout by providing a means whereby 
excess Gila trout may be placed in waters that can provide a 
recreational benefit, thereby avoiding potential overcrowding in the 
designated recovery streams. Additionally, the special rule contributes 
to the conservation of the Gila trout through: (1) Eligibility for 
Federal sport fishing funds, (2) increase in the number of wild 
populations, (3) enhanced ability to monitor populations (e.g., creel 
censuses) for use in future management strategies, and (4) creation of 
goodwill and support in the local community. Each of these topics is 
discussed in detail in the ``Description of Proposed Special Rule'' 
section below.
    A few Gila trout are removed from the wild for propagation, and 
some are taken for scientific or educational proposes, but the take is 
small and controlled through Federal and State permitting. Federal and 
State permitting will continue. Because of the remoteness of current 
and proposed recovery streams, the special regulations that will be 
imposed on angling, and the small amount of Gila trout collected for 
scientific and educational purposes, we determine that overutilization 
for recreational, scientific, or educational purposes is not a threat 
to Gila trout.

C. Disease or Predation

    The carrier of bacterial kidney disease (BKD) is known to occur in 
trout in the upper West Fork drainage. The carrier, a bacterium 
(Renibacterium salmoninarum), occurs in very low amounts in brown trout 
populations in the upper West Fork Gila River drainage and in the 
Whiskey Creek population of Gila trout. The bacterium was also detected 
in rainbow x Gila trout hybrid populations in Iron, McKenna, and White 
Creeks. Although the carrier bacterium is present, there were no signs 
of BKD in any Gila trout populations (Service 2003). Trout populations 
in the Mogollon Creek drainage, McKnight Creek, Sheep Corral Canyon, 
and Spruce Creek all tested negative for BKD.
    Whirling disease (WD) was first detected in Pennsylvania, in 1956, 
and was transmitted here from fish brought from Europe (Thompson et al. 
1995). Myxobolus cerebralis is a parasite that penetrates through the 
skin or digestive tract of young fish and migrates to the spinal 
cartilage, where it multiplies very rapidly, putting pressure on the 
organ of equilibrium. This causes the fish to swim erratically (whirl) 
and have difficulty feeding and avoiding predators. In severe 
infections, the disease can cause high rates of mortality in young-of-
the-year fish. Water temperature, fish species and age, and dose of 
exposure are critical factors influencing whether infection will occur 
and its severity (Hedrick et al. 1999). Fish that survive until the 
cartilage hardens to bone can live a normal life span, but have 
skeletal deformities. Once a fish reaches 3 to 4 inches in length, 
cartilage forms into bone and the fish is no longer susceptible to 
effects from whirling disease. Fish can reproduce without passing the 
parasite to their offspring; however, when an infected fish dies, many 
thousands to millions of the parasite spores are released to the water. 
The spores can withstand freezing, desiccation, passage through the gut 
of mallard ducks, and can survive in a stream for many years (El-
Matbouli and Hoffmann 1991). Eventually, the spore is ingested by its 
alternate host, the common aquatic worm, Tubifex tubifex. After about 
3.5 months in the gut of the worms, the spores transform into a 
Triactinomyon (TAM). The TAMs leave the worm and attach to the fish or 
they are ingested when the fish eats the worm. The spores are easily 
transported by animals, birds, and humans.
    Salmonids native to the United States did not evolve with WD. 
Consequently, most native species have little or no natural resistance. 
Colorado River cutthroat trout and rainbow trout are very susceptible 
to the disease, with 85 percent mortality within 4 months of exposure 
to ambient levels of infectivity in the Colorado River (Thompson et al. 
1999). Brown trout, native to Europe,

[[Page 24758]]

evolved with M. cerebralis, become infected but rarely suffer clinical 
disease. At the study site on the Colorado River, brown trout thrive, 
but there has been little survival beyond 1 year of age of rainbow 
trout since 1992 (Thompson et al. 1999). Gila trout are also vulnerable 
to WD (D. Shroufe, Arizona Game and Fish Department, in litt. 2003a).
    There have been no documented cases of WD in the Gila River 
drainage in New Mexico or Arizona. Wild and hatchery populations of 
Gila trout tested have been negative for WD (Service 2003). Although WD 
is a potential threat to Gila trout, high infection rates would 
probably only occur where water temperatures are relatively warm and 
where T. tubifex is abundant. T. tubifex is the secondary host for the 
parasite; when T. tubifex numbers are low, the number of TAMs produced 
will be low, and consequently, the infection rate of Gila trout will be 
low. T. tubifex is an ubiquitous aquatic oligochaete (worm); however, 
it is most abundant in degraded aquatic habitats, particularly in areas 
with high sedimentation, warm water temperatures, and low dissolved 
oxygen. In clear coldwater streams (typical Gila trout habitat) it is 
present but seldom abundant. Infection rate is low at temperatures less 
than 10[deg]C (50[deg]F) (Thompson et al. 1999).
    We determine that BKD is not a threat to the 4 original pure 
populations or the 10 replicated populations because of its limited 
distribution, low occurrence within the trout populations, and lack of 
any clinical evidence of the disease in Gila trout. Likewise, we 
determine that WD is not a threat to Gila trout because they are 
located in high-elevation headwater streams that typically have cold 
water and low levels of sedimentation, which limit T. tubifex 
populations and infection rates from TAMs. Although Gila trout may be 
susceptible to infection, there has not been a documented occurrence of 
WD in a wild Gila trout population. Mora National Fish Hatchery and 
Technology Center, where Gila trout have been held, has tested negative 
for WD. In addition, NMDGF and AGFD are educating the public about how 
to prevent the spread of WD (e.g., through educational brochures and 
information provided with fishing regulations).
    Predation of Gila trout by brown trout has been a serious problem, 
and continues to be a problem for fish below stream barriers. Brown 
trout, a non-native salmonid, preys on Gila trout and is able to 
severely depress Gila trout populations. Predation threats have been 
addressed by chemically removing all non-native fish and reintroducing 
only native species. The specific locations and timing of the potential 
use of chemicals in any future stream restoration projects would be 
made by the States in coordination with the Recovery Team. 
Additionally, the Gila Trout Recovery Plan provides a list of potential 
stream reaches that may be used for recovery purposes. Physical stream 
barriers, either natural waterfalls or constructed waterfalls (e.g., 
either composite concrete/rock or basket-type gabion) built by 
cooperating agencies, prevent brown trout from moving upstream and 
preying on Gila trout. Barrier failure is generally not considered a 
threat to existing Gila trout populations in New Mexico because most 
existing barriers are natural waterfalls. However, human-made barriers 
exist on lower Little Creek, McKnight Creek, and Black Canyon. Failure 
of human-made barriers would most likely result from catastrophic 
flooding and include scouring around barriers, undercutting, or 
complete removal. Brown trout and other non-native species downstream 
from these barriers remain a threat.
    The threat of predation by brown trout has been reduced by 
eliminating brown trout from streams with Gila trout populations, and 
by creating barriers that prevent the upstream dispersal of brown trout 
into areas occupied by Gila trout. Field monitoring by the Service, 
Forest Service, AGFD, and the NMDGF of Gila trout provides a means to 
detect the introduction of brown trout into a Gila trout population, 
and, once detected the non-natives are removed (Service 2004). Each 
population is monitored at least once every 3 years. Monitoring may 
occur more, often depending upon the situation, such as additional 
surveys due to the occurrence of wildfire. Annual monitoring using 
electrofishing is not undertaken due to potential sampling impacts from 
electrofishing. The Emergency Plan provides further information on the 
procedures for detecting and addressing the threat of non-natives 
(Service 2004).

D. The Inadequacy of Existing Regulatory Mechanisms

    Before the Gila trout was federally listed as endangered (1967), 
the species had no legal protection. Upon being listed under the Act, 
the Gila trout immediately benefited from a Federal regulatory 
framework that provided protection and enhancement of the populations 
in three ways. First, take was prohibited. Take is defined under the 
Act to include killing, harassing, harming, capturing, or collecting 
individuals or attempting to do any of these things. Habitat 
destruction or degradation is also prohibited if such activities harm 
individuals of the species. Second, section 7 of the Act requires that 
Federal agencies consult with the Service to ensure that their actions 
will not likely jeopardize the continued existence of the species. 
Third, once a species is listed, the Service is required to complete a 
recovery plan and make timely revisions, if needed. Thus, listing the 
species provided recognition, protection, and prohibitions against 
certain practices (such as take), facilitated habitat protection, and 
stimulated recovery actions.
    Subsequent to the Federal listing action, the States of New Mexico 
and Arizona officially recognized the declining status of the species. 
Arizona designated the Gila trout as an endangered species in 1988, 
which includes species that are known or suspected to have been 
extirpated from Arizona but that still exist elsewhere. New Mexico 
designated the Gila trout as an endangered species (Group 1) on January 
24, 1975 (NM State Game Commission Regulation No. 663) under authority 
of the Wildlife Conservation Act. Group 1 species are those whose 
prospects of survival or recruitment in New Mexico are in jeopardy. The 
designation provides the protection of the New Mexico Wildlife 
Conservation Act (Sections 17-2-37 through 17-2-18 NMSA 1978) and 
prohibits taking of such species except under a scientific collecting 
permit. New Mexico also has a limited ability to protect the species' 
habitat through the Habitat Protection Act (Sections 17-3-1 through 17-
3-11) through water pollution legislation, and tangentially through a 
provision that makes it illegal to dewater areas used by game fish 
(Section 17-1-14). Take of Gila trout in Arizona is prohibited through 
State statute (Arizona Revised Statute Title 17) and Commission Order 
(Commission Order 40). We do not expect any changes in the current 
State protections provided to the Gila trout as a result of this rule. 
However, if our proposed special rule is finalized, the States of 
Arizona and New Mexico will likely be adopting regulations to allow for 
recreational fishing as described in the ``Description of the Proposed 
Special Rule'' section below.
    We determine that because of the protection that would be provided 
from Federal listing as a threatened species, along with this proposed 
special rule, State regulatory protection, and habitat protection 
provided by the National Forests, there are adequate regulatory 
mechanisms to protect and enhance Gila trout populations and their 
habitat.

[[Page 24759]]

Many of these protective regulations, conservation measures, and 
recovery actions have substantially improved the status of the Gila 
trout.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    When the Gila trout was listed as endangered, the most important 
reason for the species' decline was hybridization and competition with 
and/or predation by non-native salmonids (52 FR 37424). Uncontrolled 
angling depleted some populations of Gila trout, which in turn 
encouraged stocking of hatchery-raise