[Federal Register Volume 71, Number 85 (Wednesday, May 3, 2006)]
[Proposed Rules]
[Pages 26007-26017]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-6648]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List a Distinct Population Segment of the Roundtail
Chub in the Lower Colorado River Basin and To List the Headwater Chub
as Endangered or Threatened With Critical Habitat
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list a distinct population segment
(DPS) of the roundtail chub (Gila robusta) in the lower Colorado River
basin, and to list the headwater chub (G. nigra) as endangered or
threatened under the Endangered Species Act of 1973, as amended (Act).
The petition also asked the Service to designate critical habitat.
After review of all available scientific and commercial information, we
find that the petitioned action is not warranted for a DPS of the
roundtail chub in the lower Colorado River basin, as explained below,
but that listing is warranted for the headwater chub. Currently,
however, listing of the headwater chub is precluded by higher priority
actions to amend the Lists of Endangered and Threatened Wildlife and
Plants. Upon publication of this 12-month petition finding, the
headwater chub will be added to our candidate species list. We will
develop a proposed rule to list the headwater chub as our priorities
allow. Any determinations on critical habitat will be made during
development of the proposed rule.
DATES: The finding announced in this document was made on April 27,
2006.
ADDRESSES: The complete file for this finding is available for
inspection, by appointment, during normal business hours at the Arizona
Ecological Services Office, 2321 West Royal Palm Road, Suite 103,
Phoenix, AZ 85021-4951. Please submit any new information, materials,
comments, or questions
[[Page 26008]]
concerning this species or this finding to the above address.
FOR FURTHER INFORMATION CONTACT: Field Supervisor, Arizona Ecological
Services Office, at the address above (602-242-0210).
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.), requires
that, for any petition to revise the List of Threatened and Endangered
Species that contains substantial scientific and commercial information
that listing may be warranted, we make a finding within 12 months of
the date of receipt of the petition on whether the petitioned action is
(a) not warranted, (b) warranted, or (c) warranted, but that the
immediate proposal of a regulation implementing the petitioned action
is precluded by other pending proposals to determine whether any
species is threatened or endangered, and expeditious progress is being
made to add or remove qualified species from the Lists of Endangered
and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act
requires that a petition for which the requested action is found to be
warranted but precluded be treated as though resubmitted on the date of
such finding, i.e., requiring a subsequent finding to be made within 12
months. Each subsequent 12-month finding will be published in the
Federal Register.
On April 14, 2003, we received a petition dated April 2, 2003,
requesting that we list a distinct population segment (DPS) of the
roundtail chub in the lower Colorado River basin as endangered or
threatened, that we list the headwater chub as endangered or
threatened, and that we designate critical habitat concurrently with
the listing for both species. The petition, submitted by the Center for
Biological Diversity (Center), was clearly identified as a petition for
a listing rule, and it contained the names, signatures, and addresses
of the requesting parties. Included in the petition was supporting
information regarding the species' taxonomy and ecology, historical and
current distribution, present status, and potential causes of decline.
We acknowledged the receipt of the petition in a letter to Mr. Noah
Greenwald, dated June 4, 2003. In that letter, we also advised the
petitioners that, due to funding constraints in fiscal year 2003, we
would not be able to begin processing the petition in a timely manner.
On May 18, 2004, the Center sent a Notice of Intent to sue,
contending that the Service had violated the Act by failing to make a
timely 90-day finding on the petition to list a DPS of the roundtail
chub in the lower Colorado River basin, and the headwater chub. On
September 20, 2004, the Center filed a complaint against the Secretary
of the Interior and the Service for failure to make a 90-day petition
finding under section 4 of the Act. In a stipulated settlement
agreement we agreed to submit a 90-day finding to the Federal Register
by June 30, 2005 (Center for Biological Diversity v. Norton, CV-04-496-
TUC-CKJ (D. AZ)). The settlement agreement was approved by the District
Court for the District of Arizona on May 5, 2005. On June 30, 2005, we
made our 90-day finding that the petition presented substantial
scientific information indicating that listing the roundtail chub as a
DPS in the lower Colorado River basin, and the headwater chub
throughout its range, may be warranted. The finding and our initiation
of a status review was published in the Federal Register on July 12,
2005 (70 FR 39981). We are required, pursuant to the court-approved
stipulated settlement agreement, to make our 12-month finding pursuant
to the Act (16 U.S.C. 1533(b)(3)(B)) on or before April 6, 2006. This
notice constitutes our 12-month finding for the petition to list a DPS
of the roundtail chub in the lower Colorado River basin, and to list
the headwater chub, as endangered or threatened.
Biology
The roundtail and headwater chubs are both cyprinid fish (members
of Cyprinidae, the minnow family) with streamlined body shapes. Color
in roundtail chub is usually olive-gray to silvery, with the belly
lighter, and sometimes with dark blotches on the sides; headwater chub
color is usually dark gray to brown overall, with silvery sides that
often have faded lateral stripes. Roundtail chub are generally 25 to 35
centimeters (cm) (9 to 14 inches (in)) in length, but can reach 50 cm
(20 in). Headwater chub are quite similar in appearance to roundtail
chub, although they are generally smaller, likely due to the smaller
streams in which they occur (Minckley 1973; Sublette et al. 1990;
Propst 1999; Minckley and Demaris 2000; Voeltz 2002).
Baird and Girard (1852) first described roundtail chub from
specimens collected from the Zuni River in northeastern Arizona and
northwestern New Mexico. Headwater chub was first described from Ash
Creek and the San Carlos River in east-central Arizona in 1874 (Cope
and Yarrow 1875). Since the 1800s, both roundtail and headwater chub
have been recognized as distinct entities, although at varying
taxonomic levels (Miller 1945; Holden 1968; Rinne 1969; Holden and
Stalnaker 1970; Rinne 1976; Smith et al. 1979; DeMarais 1986; Rosenfeld
and Wilkinson 1989; DeMarais 1992; Dowling and DeMarais 1993; Douglas
et al. 1998; Minckley and DeMarais 2000; Gerber et al. 2001). At
present, both are recognized as distinct species, based on discrete
occurrences of specific morphology (Minckley and DeMarais 2000). Both
roundtail and headwater chub are recognized as species on the American
Fisheries Society's most recent list of accepted common and scientific
names of fishes (Nelson et al. 2004).
Roundtail Chub Distinct Population Segment
In the petition to list these species, we were asked to consider
designating a DPS for the roundtail chub in the lower Colorado River
basin. Under the Act, we must consider for listing any species,
subspecies, or, DPSs of vertebrate species/subspecies, if information
is sufficient to indicate that such action may be warranted. To
implement the measures prescribed by the Act and its Congressional
guidance, we developed a joint policy with the National Oceanic and
Atmospheric Administration (NOAA) Fisheries entitled Policy Regarding
the Recognition of Distinct Vertebrate Population (DPS Policy) to
clarify our interpretation of the phrase ``distinct population segment
of any species of vertebrate fish or wildlife'' for the purposes of
listing, delisting, and reclassifying species under the Act (61 FR
4721; February 7, 1996). Under our DPS policy, we consider three
elements in a decision regarding the status of a possible DPS as
endangered or threatened under the Act. The elements are: (1) The
population segment's discreteness from the remainder of the taxon to
which it belongs; (2) the population segment's significance to the
taxon to which it belongs; and (3) the population segment's
conservation status in relation to the Act's standards for listing
(i.e., when treated as if it were a species, is the population segment
endangered or threatened?). Our policy further recognizes it may be
appropriate to assign different classifications (i.e., threatened or
endangered) to different DPSs of the same vertebrate taxon (61 FR 4721;
February 7, 1996).
Discreteness
The DPS policy's standard for discreteness requires an entity given
DPS status under the Act to be
[[Page 26009]]
adequately defined and described in some way that distinguishes it from
other populations of the species. The historical range of the roundtail
chub included both the upper and lower Colorado River basins in the
States of Wyoming, Utah, Colorado, New Mexico, Arizona, and likely
Nevada and Baja California and Sonora, Mexico (Propst 1999; Bezzerides
and Bestgen 2002; Voeltz 2002). In recent times, the upper and lower
basin populations of the roundtail chub have been physically separated
by the Glen Canyon Dam. Results from comparisons of genetic information
of roundtail chubs between the lower and upper basins of the Colorado
River were based on small sample sizes and provided inconclusive
results (DeMarais 1992; Dowling and DeMarais 1993; Minckley and
DeMarais 2000; Gerber et al. 2001). Therefore, the best available
scientific data are not conclusive on the question of whether the lower
basin populations of the roundtail chub are discrete from the upper
basin populations. However, because we determine in the following
section that the lower basin populations are not significant to the
taxon as a whole, we need not address further the ``discreteness'' test
of the DPS policy.
Significance
Under our DPS policy, a population segment must be significant to
the taxon to which it belongs. The evaluation of ``significance'' may
address, but is not limited to, (1) Evidence of the persistence of the
discrete population segment in an ecological setting that is unique for
the taxon; (2) evidence that loss of the population segment would
result in a significant gap in the range of the taxon; (3) evidence
that the population segment represents the only surviving natural
occurrence of a taxon that may be more abundant elsewhere as an
introduced population outside its historic range; and (4) evidence that
the discrete population segment differs markedly from other populations
of the species in its genetic characteristics.
Ecological Setting. Based on our review of the available
information, we found that there are some differences in various
ecoregion variables between the upper and lower Colorado River basins.
For example, McNabb and Avers (1994) and Bailey (1995) delineated
ecoregions and sections of the United States based on a combination of
climate, vegetation, geology, and other factors. Populations of
roundtail chub in the lower basin are primarily found in the Tonto
Transition and Painted Desert Sections of the Colorado Plateau Semi-
Desert Province in the Dry Domain, and the White Mountain-San Francisco
Peaks-Mogollon Rim Section of the Arizona-New Mexico Mountains Semi-
Desert-Open Woodland-Coniferous Forest Province Dry Domain. Populations
of roundtail chub in the upper basin are primarily found in the
Northern Canyonlands and Uinta Basin Sections of the Intermountain
Semi-Desert and Desert Province in the Dry Domain, and the Tavaputs
Plateau and Utah High Plateaus and Mountains Sections of the Nevada-
Utah Mountains Semi-Desert-Coniferous Forest Province in the Dry Domain
(McNabb and Avers 1994; Bailey 1995). These ecoregion differences
result in differences in hydrograph, sediment, substrate, nutrient
flow, cover, water chemistry, and other habitat variables of roundtail
chub. Also, there are differences in type, timing, and amount of
precipitation between the two basins, with the upper basin (3-65
inches/year (Sims 1968)) somewhat less arid than the lower (5-25
inches/year (Green and Sellers 1964)).
The type and timing of precipitation, which are major factors in
determining the pattern of streamflow, and which when plotted as the
amount of runoff or discharge against time are known as a hydrograph
(Dunne and Leopold 1978), also appear to be somewhat different between
the two basins. The hydrograph of a stream is a major factor in
determining habitat characteristics and their variability over space
and time. Habitats of roundtail chub in the lower basin have a monsoon
hydrograph or a mixed monsoon-snowmelt hydrograph. A monsoon hydrograph
results from distinctly bimodal annual precipitation, which creates
large, abrupt, and highly variable flow events in late summer and
large, longer, and less variable flow events in the winter (Burkham
1970; Sellers 1974; Minckley and Rinne 1991). Monsoon hydrographs are
characterized by high variability, including rapid rise and fall of
flow levels with flood peaks of one or more orders of magnitude greater
than base, or ``normal low'' flow (Burkham 1970).
In the upper basin, roundtail chub habitats have strong snowmelt
hydrographs, with some summer/fall/winter precipitation, but with the
majority of major flow events in spring and early summer (Bailey 1995;
Carlson and Muth 1989; Miller and Hubert 1990). Snowmelt hydrographs
are characterized by low variability, long, slow rises and falls in
flow and peak flow events that are less than an order of magnitude
greater than the base flow.
The lower basin has lower stream flows and warmer temperatures in
late spring and early summer; whereas this is typically the wettest
period in the upper basin. Sediment loads vary substantially between
streams in both basins, but are generally lesser in the upper basin
than the lower (Carlson and Muth 1989), and patterning of sediment
movement differs substantially because of the different hydrographs. In
general, roundtail chub habitat in the lower Colorado River basin is of
lower gradient, smaller average substrate size, higher water
temperatures, higher salinity, smaller base flows, higher flood peaks,
lesser channel stability and higher erosion, and substantially
different hydrographs than the habitat in the upper Colorado River
basin.
Measurable hydrographic differences between the two basins are
evident, as are differences in landscape level roundtail chub habitats
between the upper and lower basins; these differences, however, do not
appear to result in significant disparities in life history of
roundtail chubs between the two basins. Roundtail chub in the upper and
lower basins have basically the same life history and occupy similar
in-stream habitats (Besserides and Bestgen 2002; Voeltz 2002).
Furthermore, loss of the lower basin roundtail chub would not result in
a loss of a form of the species that occurs in a setting unique from
that found in the upper basin.
Gap in the Range and Marked Differences in Genetic Characteristics.
Roundtail chub in the lower Colorado River basin is at the southern
portion of the historic and current distribution of the species.
Although the species may have occurred in Mexico, there are no records
to support this. Within the distribution of every species there exists
a peripheral population, an isolate or subpopulation of a species at
the edge of the taxon's range. Long-term geographic isolation and loss
of gene flow between populations is the foundation of genetic changes
in population resulting from natural selection or change. Evidence of
changes in these populations may include genetic, behavioral, and/or
morphological differences from populations in the rest of the species'
range. While the available genetic information is sparse, it indicates
that roundtail chubs sampled from Chevelon Creek in the Little Colorado
River drainage of the lower Colorado River basin share the same mtDNA
haplotype with upper basin roundtail chubs (Gerber et al. 2001; as
discussed above under ``Discreteness''). Therefore, based on the
genetic information currently available, roundtail chub in the lower
Colorado River basin should not be considered biologically or
ecologically significant based simply on genetic characteristics. We
also considered
[[Page 26010]]
information regarding morphological and behavioral differences with
regard to adaptations that may be occurring in the lower Colorado River
basin roundtail chub and found no evidence of any differences.
Biological and ecological significance under the DPS policy is always
considered in light of Congressional guidance (see Senate Report 151,
96th Congress, 1st Session) that the authority to list DPS's be used
''sparingly'' while encouraging the conservation of genetic diversity.
Whether the Population Represents the Only Surviving Natural
Occurrence of the Taxon. As part of a determination of significance,
our DPS policy suggests that we consider whether there is evidence that
the population represents the only surviving natural occurrence of a
taxon that may be more abundant elsewhere as an introduced population
outside its historic range. The roundtail chub in the lower Colorado
River basin is not the only surviving natural occurrence of the
species. Consequently, this factor is not applicable to our
determination regarding significance.
Conclusion
Following a review of the available information, we conclude that
the roundtail chub populations in the lower Colorado River basin are
not significant to the remainder of the taxon. We made this
determination based on the best available information, which does not
demonstrate that (1) these populations persist in an ecological setting
that is unique for the taxon; (2) the loss of these populations would
result in a significant gap in the range of the taxon; and (3) these
populations differ markedly from populations of roundtail chub in the
upper basin in their genetic characteristics, or in other
considerations that might demonstrate significance. Further, available
information does not demonstrate that the life history and behavioral
characteristics of roundtail chub in the lower basin are unique to the
species. Therefore, on the basis of the best scientific and commercial
information available, we find that proposing to list a DPS for the
lower Colorado River basin populations of roundtail chub is not
warranted; these populations do not meet our definition of a distinct
population segment.
Headwater Chub
Distribution
The historical distribution of headwater chub in the lower Colorado
River basin is poorly documented, due to the paucity of early
collections and the widespread anthropogenic (manmade) changes (i.e.,
habitat alteration and nonnative species introductions (Girmendonk and
Young 1997)) to aquatic ecosystems beginning in the mid 19th century.
The headwater chub was historically considered common throughout its
range (Minckley 1973; Holden and Stalnaker 1975; Propst 1999). Voeltz
(2002), estimating historical distribution based on museum collection
records, agency database searches, literature searches, and discussion
with biologists, found that headwater chub likely occurred in a number
of tributaries of the Verde River, most of the Tonto Creek drainage,
much of the San Carlos River drainage, and parts of the upper Gila
River in New Mexico (Voeltz 2002). Voeltz (2002) estimated that
headwater chub historically occupied approximately 500 km (312 mi) in
Arizona and New Mexico. The species currently occurs in the same areas,
but has a smaller distribution. In Arizona, four tributaries of the
Verde River (Fossil Creek, the East Verde River, Wet Bottom Creek, and
Deadman Creek), and Tonto Creek and eight of its tributaries (Buzzard
Roost, Gordon, Gun, Haigler, Horton, Marsh, Rock, Spring, and Turkey
Creeks), are currently occupied; and in New Mexico, in the upper East
Fork, lower Middle Fork, and lower West Forks of the Gila River (Voeltz
2002; S. Stefferud in litt. 2005) support headwater chub. Headwater
chub may still occur in parts of the San Carlos River basin; however
recent survey information for these streams is unavailable (Minckley
and DeMarais 2000, Voeltz 2002).
Headwater chub occur in the middle to upper reaches of moderately-
sized streams (Minckley and Demaris 2000). Bestgen and Propst (1989)
examined status and life history in the Gila River drainage in New
Mexico and found that headwater chubs occupied tributary and mainstem
habitats in the upper Gila River at elevations of 1,325 meters (m)
(4,347 feet (ft)) to 2,000 m (6,562 ft). Maximum water temperatures of
headwater chub habitat varied between 20 to 27 [deg]C, and minimum
water temperatures were around 7 [deg]C (Bestgen and Propst 1989;
Barrett and Maughan 1995). Typical adult microhabitat consists of
nearshore pools adjacent to swifter riffles and runs over sand and
gravel substrate, with young of the year and juvenile headwater chub
using smaller pools and areas with undercut banks and low current
(Anderson and Turner 1978; Bestgen and Propst 1989). Spawning in Fossil
Creek occurred in spring and was observed in March in pool-riffle areas
with sandy-rocky substrates (Neve 1976). Neve (1976) reported that the
diet of headwater chub included aquatic insects, ostracods (small
crustaceans), and plant material.
Previous Federal Actions
We placed the roundtail chub (as G. r. grahami, which then included
headwater chub) on the list of candidate species as a category 2
species on December 30, 1982 (47 FR 58454) and on January 6, 1989 (54
FR 554). Category 2 species were those for which existing information
indicated that listing was possibly appropriate, but for which
substantial supporting biological data were lacking. On November 21,
1991 (56 FR 58804), we continued to list headwater chub (now referred
to as G. robusta, which included headwater and roundtail chub) as a
category 2 species. Due to lack of funding to gather existing
information on these fishes, they remained in category 2 through the
1994 (59 FR 58982; November 15, 1994) Candidate Notices of Review. In
the 1996 Candidate Notice of Review (61 FR 7596; February 28, 1996),
category 2 was eliminated, and roundtail and headwater chub were no
longer recognized as candidates for listing. Following receipt of the
2002 petition, and pursuant to a stipulated settlement agreement, we
published a 90-day finding on July 12, 2005 (70 FR 39981), in which we
found that the petitioners had provided sufficient information to
indicate that listing of the roundtail and headwater chubs may be
warranted. In order to ensure we had the best scientific and commercial
information available to determine whether listing of these species was
indeed warranted, we opened a 60-day public comment period, ending
September 12, 2005, and commenced a status review.
Status of the Headwater Chub
Headwater chub (as G. robusta grahami) was considered a threatened
species by the American Fisheries Society on its list of fishes
receiving legal protection and of special concern in 1987 (Johnson
1987). Since that time, declines of the headwater chub have been
further noted both in the scientific peer reviewed literature (Bestgen
and Propst 1989) and in State agency reports (Girmendonk and Young
1997; Brouder et al. 2000; Bezzerides and Bestgen 2002; Voeltz 2002).
The most comprehensive and recent of the status reports concerning
headwater chub was completed by the Arizona Game and Fish Department in
2002, and peer-reviewed by Federal agency personnel, university
researchers, and experts on the headwater chub (AGFD; Voeltz 2002).
[[Page 26011]]
Stream-specific distribution and status information for roundtail and
headwater chub populations in the lower Colorado River basin was
gathered from published literature; unpublished agency reports,
records, manuscripts, and files; scientific collecting permit reports;
personal communications with knowledgeable biologists; and academic
databases. Based on this comprehensive information on all available
current and historical survey records, AGFD estimated historical and
current ranges of the headwater chub and found that the species had
declined significantly from historical levels. The AGFD report also
used a classification system, as described below in Table 1, to report
status and threat information, which defined populations based on the
abundance and recruitment of the population and presence or absence of
obvious threats.
Table 1.--Definitions of Status Description Categories Used To Describe
the Status of Headwater Chub Populations
[From Voeltz 2002]
------------------------------------------------------------------------
Status Definition
------------------------------------------------------------------------
Stable-Secure..................... Chubs are abundant or common, data
over the past 5-10 years shows a
stable, reproducing population with
successful recruitment; no impacts
from nonnative aquatic species
exist; and no current or future
habitat altering land or water uses
were identified.
Stable-Threatened................. Chubs are abundant or common, data
over the past 5-10 years shows a
reproducing population, although
recruitment may be limited;
predatory or competitive threats
from nonnative aquatic species
exist; and/or some current or
future habitat altering land or
water uses were identified.
Unstable-Threatened............... Chubs are uncommon or rare with a
limited distribution; data over the
past 5-10 years shows a declining
population with limited
recruitment; predatory or
competitive threats from nonnative
aquatic species exist; and/or
serious current or future habitat
altering land or water uses were
identified.
Extirpated........................ Chubs are no longer believed to
occur in the system.
Unknown........................... Lack of data precludes determination
of status.
------------------------------------------------------------------------
Voeltz (2002) reviewed the 19 currently known populations of
headwater chub and found that one was stable-secure, six were stable-
threatened, six were unstable-threatened, three were extirpated, and
three were unknown. Deadman Creek, the one population that Voeltz
considered stable-secure, has since been invaded by nonnative green
sunfish (Lepomis cyanella) (Voeltz, Arizona Game and Fish Department,
pers. comm. 2003), and should now be considered stable-threatened.
Headwater chub are known to occupy only 40 percent of their former
range, and have an unknown distribution on another 10 percent of their
former range. Based on the best available scientific information, the
headwater chub occurs in 16 of 19 known populations, which now occur in
fragmented and isolated stream segments and represent only 40 to 50
percent of the species' former range (approximately 200 km (125 mi) of
500 km (312 mi)) in Arizona and New Mexico (Voeltz 2002).
Populations of headwater chub are found in four separate drainage
basins that are isolated from one another (the Verde River, Tonto
Creek, San Carlos River, and upper Gila River). Within these four
basins, there is further fragmentation and isolation of some
populations. We consider a particular basin to be at risk of
extirpation if there are fewer than a minimum of two stable-secure
populations because any single population can be eliminated by
stochastic events or catastrophic disturbance, such as fire (see Meffe
and Carroll 1994). According to information in Voeltz (2002), and
survey information collected since that time (as described above),
headwater chub cannot be considered secure in any drainage because
there are no stable-secure populations in any drainage in which they
occur.
In summary, the data show that the status of headwater chub is poor
and declining. It has been extirpated from approximately 50 percent of
its historical range; all 16 known populations are experiencing threats
(see ``Summary of Factors Affecting the Headwater Chub'' discussion and
Table 2 below); and it is no longer considered secure in any part of
its historical range (Voeltz 2002; Voeltz, Arizona Game and Fish
Department, pers. comm. 2003). Although 6 of the 16 extant populations
are considered ``stable'' based on abundance and evidence of
recruitment, we believe all six of these populations have a high
likelihood of becoming extirpated in the foreseeable future, primarily
because at least one, and in most cases several, nonnative aquatic
species that have been implicated in the decline of headwater chub are
present in these streams (Voeltz 2002).
Summary of Factors Affecting the Headwater Chub
Section 4 of the Act (16 U.S.C. 1533), and implementing regulations
at 50 CFR 424, set forth procedures for adding species to the Federal
List of Endangered and Threatened Species. Under section 4(a) of the
Act, we may list a species on the basis of any of five factors, as
follows: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or man-made factors affecting its
continued existence. In making this finding, information regarding the
status of, and threats to, the headwater chub in relation to the five
factors provided in section 4(a)(1) of the Act is discussed below and
summarized in Table 2 below.
Table 2.--Summary of Headwater Chub Status and Threats by Stream Reach
[Voeltz 2002; Voetlz, AGFD, pers. comm. 2003]
------------------------------------------------------------------------
Stream reach Status Threats
------------------------------------------------------------------------
Christopher Creek............... E Considered extirpated
by nonnative species.
Horton Creek.................... E Considered extirpated
by nonnative species.
Rye Creek....................... E Considered extirpated
by nonnative species.
[[Page 26012]]
Deadman Creek................... ST Nonnatives, grazing,
recreation.
Buzzard Roost Creek............. ST Roads, channelization,
grazing, mining,
nonnatives,
recreation, logging,
water use, fire.
Gordon Creek.................... ST Roads, grazing,
nonnatives,
recreation, logging,
fire.
Haigler Creek................... ST Roads, grazing,
nonnatives,
recreation, logging,
fire.
Marsh Creek..................... ST Roads, grazing,
nonnatives,
recreation, logging,
fire.
Rock Creek...................... ST Roads, grazing, mining,
nonnatives,
recreation, logging,
fire.
Spring Creek.................... ST Roads, grazing, mining,
nonnatives,
recreation, logging,
fire.
Ash Creek....................... U Roads, grazing,
nonnatives,
recreation, fire.
Wet Bottom Creek................ U Roads, grazing,
nonnatives,
recreation, fire.
San Carlos River................ U Roads, channelization,
grazing, nonnatives,
recreation, water use.
Upper Gila River................ UT Roads, channelization,
development, grazing,
mining, nonnatives,
recreation, logging,
water use, fire.
Gun Creek....................... UT Roads, channelization,
grazing, mining,
nonnatives,
recreation, logging,
fire.
Tonto Creek..................... UT Roads, channelization,
development, grazing,
mining, nonnatives,
recreation, logging,
water use, fire.
East Verde River................ UT Roads, channelization,
development, grazing,
nonnatives,
recreation, logging,
water use, fire.
Fossil Creek.................... UT Roads, channelization,
development, grazing,
nonnatives,
recreation, logging,
water use, fire.
Webber Creek.................... UT Roads, channelization,
development, grazing,
nonnatives,
recreation, logging,
water use, fire.
------------------------------------------------------------------------
E=extirpated; ST=stable, threatened; U=unknown; UT=unstable, threatened.
Factor A: The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Within the historical range of the headwater chub, much of the
stream habitat has been destroyed or degraded, and loss of this habitat
continues today (Minckley 1973; Tellman et al. 1997; Propst 1999;
Voeltz 2002). At certain locations, activities such as groundwater
pumping, surface water diversions, impoundments, dams, channelization
(straightening of the natural watercourse, typically for flood control
purposes), improperly managed livestock grazing, wildfire, agriculture,
mining, roads, logging, residential development, and recreation all
contribute to riparian and cienega (wetland) habitat loss and
degradation in Arizona and New Mexico (Minckley and Deacon 1991;
Tellman et al. 1997; Propst 1999; Voeltz 2002). These activities and
their effects on headwater chub are discussed in further detail below.
Water withdrawal. Headwater chub has been eliminated from much of
its historical range because many areas formerly occupied are now
unsuitable due to dewatering (Miller 1961; Miller 1972; Minckley 1973;
Deacon et al. 1979; Williams et al. 1987; Bestgen and Propst 1989;
Girmendonk and Young 1997; Bezzerides and Bestgen 2002; Voeltz 2002).
Habitat for these fishes is likely eliminated once surface flow drops
below 0.3 cubic meters per second (10 cubic feet per second) because
the stream lacks the depth and habitat features, such as deep pools,
that the species requires (U.S. Fish and Wildlife Service 1989). The
upper Gila River, in the vicinities of Cliff, Redrock, and Virden, New
Mexico, has been entirely dewatered on occasion by diversions for
agriculture (Bestgen 1985). In addition, the communities of Strawberry,
Pine, and Payson, Arizona, are exploring means of securing municipal
water from Fossil Creek, which could substantially reduce flows in that
stream (Voeltz 2002; J. Nystedt, U.S. Fish and Wildlife Service, pers.
comm. 2004). Groundwater pumping in Tonto Creek regularly eliminates
surface flows during parts of the year (Abarca and Weedman 1993).
Groundwater pumping in the East Verde River eliminates the flow in many
parts of the stream, especially when interbasin water transfers from
Blue Ridge Reservoir are not occurring (Girmendonk and Young 1997).
Groundwater pumping in Webber Creek for municipal use, as well as at
least one diversion for agricultural use, reduces flows in that stream
(Voeltz 2002). Groundwater pumping and surface water withdrawal
directly eliminate headwater chub habitat because they remove water.
Obviously, without water, there is no fish habitat, but flowing water
also helps to create the habitat diversity that headwater chub require.
Lack of flow often results in only pool habitat remaining, which can
concentrate headwater chub with nonnative species and increase
predation pressure of nonnative fishes on headwater chub, which has
been documented in Marsh Creek and the East Verde River (Voeltz 2002).
Water withdrawal is a threat in at least 6 of the 16 extant populations
of headwater chub (Bestgen and Propst 1989; Girmendonk and Young 1997;
Propst 1999; Voeltz 2002).
Livestock grazing. Poorly managed livestock grazing has been
documented to negatively impact headwater chub habitat. Poor livestock-
grazing management is often cited as one of the most significant
factors contributing to regional stream channel downcutting (the
entrenchment of stream channels and creation of arroyos) in the late
1800s; profound effects from this period occurred throughout the
watershed of Tonto Creek, which contains 70 percent of all extant
headwater chub populations, and these effects are still evident today
and compounded by ongoing grazing (Croxen 1926; Ganda 1997). Poorly
managed livestock grazing destabilizes stream channels and disturbs
riparian ecosystem functions (Herefore 1992; Tellman et al. 1997).
Poorly managed livestock grazing negatively affects headwater chub
habitat through removal of riparian vegetation (Clary and Webster 1989;
Clary and Medin 1990; Schulz and Leininger 1990; Armour et al. 1991;
Fleishner 1994), which results in reduced bank stability, fewer pools,
and higher water temperatures, creating habitats that are too extreme
to support headwater chub (Meehan 1991; Kauffman and Krueger 1984;
Swanson et al. 1982; Minckley and Rinne 1985; Fleishner 1994; Belsky et
al. 1999). Poorly managed livestock grazing also
[[Page 26013]]
causes increased sediment in the stream channel, due to streambank
trampling and riparian vegetation loss (Weltz and Wood 1986; Waters
1995; Pearce et al. 1998). Livestock physically alter streambanks
through trampling and shearing, leading to bank erosion (Platts and
Nelson 1989; Trimble and Mendel 1995). In combination, loss of riparian
vegetation and bank erosion alters channel morphology, including
increased erosion and deposition, downcutting, and an increased width/
depth ratio, all of which lead to a loss of deep pool habitats required
by the headwater chub, and loss of shallow side and backwater habitats
used by larval chub (Trimble and Mendel 1995; Belsky et al. 1999).
Poorly managed livestock grazing causes the structure and diversity
of the fish community to shift due to changes in availability and
suitability of habitat types (Rahel and Hubert 1991). This loss of
aquatic habitat complexity reduces the diversity of habitat types
available to fish communities (Gorman and Karr 1978). In the arid west,
this loss of habitat complexity has been found to accelerate the
displacement of native fish species by nonnatives (Minckley and Rinne
1991; Baltz and Moyle 1993; Lawler et al. 1999). Livestock grazing also
contributes significantly to the introduction and spread of nonnative
aquatic species through the proliferation of ponded water in stock
tanks (U.S. Fish and Wildlife Service 2001). The U.S. Forest Service
found that livestock grazing ``may affect [headwater chub] and
eventually trend the species toward federal listing'' on allotments on
the Tonto National Forest (Biological Evaluation and Assessment for the
Green Valley Complex, Tonto National Forest 2002). Though largely a
past threat, Voeltz (2002) found that livestock grazing occurs in every
drainage in which headwater chub occur.
Stream channelization and irrigation. Sections of many Gila Basin
rivers and streams have been and continue to be channelized for flood
control, which disrupts natural channel dynamics and promotes the loss
of riparian plant communities. Channelization changes the gradient of
the stream above and below the channel. It increases streamflow in the
channelized section, which results in increased rates of erosion of the
stream and its tributaries, accompanied by gradual deposits of sediment
in downstream reaches that increase the risk of flooding (Emerson 1971;
Simpson et al. 1982). Channelization has affected headwater chub
habitat by reducing its complexity, eliminating cover, reducing
nutrient input, improving habitat for nonnative species, changing
sediment transport, altering substrate size, and reducing the length of
the stream (and therefore the amount of aquatic habitat available)
(Gorman and Karr 1978; Simpson 1982; Schmetterling et al. 2001).
Channelization occurs within at least 50 percent of extant populations
(Voeltz 2002).
Irrigation directly from streams reduces or eliminates water in
existing fish habitat. Fish can be carried into irrigation ditches,
where they may die following desiccation (drying). Irrigation dams
prevent movement of fish between populations, resulting in genetic
isolation within species; small populations are subject to genetic
threats, such as inbreeding depression (reduced health due to elevated
levels of inbreeding) and to genetic drift (a reduction in gene flow
within the species that can increase the probability of unhealthy
traits; Meffe and Carrol 1994). There are numerous surface water
diversions in headwater chub habitats, including the upper Gila River,
East Verde River, and Tonto Creek. Larger dams may also prevent
movement of fish between populations, and dramatically alter the flow
regime of streams through the impoundment of water behind and below
(Ligon et al. 1995).
Mining activities. Mining activities were more widespread
historically and likely constituted a greater threat in the past;
however, the continued mining of sand, gravel, iron, gold, copper, or
other materials remains a potential threat to the habitat of headwater
chub. The effects of mining activities on populations include adverse
effects to water quality and lowered flow rates due to dewatering of
nearby streams needed for mining operations (ADEQ 1993). Ongoing sand
and gravel mining in Tonto Creek is eliminating headwater chub habitat
(Abarca and Weedman 1993; Voeltz 2002). Sand and gravel mining removes
riparian vegetation and destabilizes streambanks, which results in
habitat loss for the headwater chub (Brown et al. 1998). Mining occurs
within at least 6 of the 16 extant populations (Voeltz 2002).
Roads and Logging. Roads have adversely affected headwater chub
habitat by destroying riparian vegetation and by increasing surface
runoff, sedimentation, and erosion (Burns 1971; Eaglin and Hubert
1993). Roads require instream structures, such as culverts and bridges,
that remove aquatic habitat and can act as barriers to fish movement
(Barrett et al. 1992; Warren and Pardew 1998). All of these activities
negatively impact headwater chub by lowering water quality and reducing
the quality and quantity of pools, by filling pools with sediments, by
reducing the quantity of large woody-debris necessary to form pools,
and by imposing barriers to movement. The end result is deterioration
of habitat for the headwater chub (Burns 1971; Eaglin and Hubert 1993).
Roads are found within every drainage containing extant populations of
headwater chub (Voeltz 2002).
Vehicular use of roads in creek bottoms, as has been documented in
Tonto Creek (Voeltz 2002), degrades headwater chub habitat and can
result in headwater chub mortality. Such use inhibits riparian plant
growth, breaks down banks, causes erosion and sedimentation, and
increases turbidity in the stream, particularly where vehicles drive
through the stream and immediately downstream of the vehicular
activity. These effects result in wider and shallower stream channels
(Meehan 1991). This causes progressive adjustments in other variables
of hydraulic geometry and results in changes to the configuration of
pools, runs, riffles, and backwaters; levels of fine sediments and
substrate embeddedness; availability of instream cover; and other fish
habitat factors in the vicinity of vehicle crossings (Rosgen 1994).
Resultant changes to the stream channels alter the way in which flood
flows interact with the stream channel and may exacerbate flood damage
to banks, channel bottoms, and riparian vegetation. The breaking down
of stream banks by vehicles reduces undercut banks and overhanging
vegetation that chub use as cover. Fish fry and eggs could also be
killed or injured if vehicles are driven through stream segments where
these life stages occur. Vehicles driven rapidly through the stream
could splash young fish or eggs onto the bank where they may desiccate.
Larger fish are likely to swim away and avoid death or injury. Public
vehicular use is also often associated with an elevated risk of human-
caused fire.
Adverse effects of stream sedimentation to fish and fish habitat
have been extensively documented (Murphy et al. 1981; Newcombe and
MacDonald 1991; Barrett et al. 1992). Excessive sedimentation causes
channel changes that are adverse to headwater chub habitat. These
activities have direct impacts on headwater chub habitat because
excessive sediment can fill backwaters and deep pools used by headwater
chub, and sediment deposition in the main channel can cause a tendency
toward stream braiding (e.g., the stream becomes wider, shallower, and
has numerous
[[Page 26014]]
channels as opposed to one channel), which reduces adult chub habitat.
Excessive sediment will smother invertebrates (Newcombe and MacDonald
1991), thereby reducing chub food production and availability, and
related turbidity reduces the chub's ability to see and capture food
(Barrett et al. 1992).
Although logging is a landuse in the watersheds of 13 of the
remaining 16 streams known to contain headwater chub populations
(Voeltz 2002), logging is largely a threat of the past, resulting from
previous management practices no longer in place. The alteration of
watersheds resulting from road-building and logging is deleterious to
fish and other aquatic life forms (e.g., Burns 1971; Eaglin and Hubert
1993). Roads and logging increase surface runoff, sedimentation, and
mudslides, and destroy riparian vegetation (Lewis 1998; Jones et al.
2000).
Recreation. Recreation was noted as a land-use in all of the
watersheds containing headwater chub (Voeltz 2002). The impacts of
recreation are highly dependant on the type of activity, with
activities such as birdwatching having little to no impact and
activities such as off-road vehicle use potentially having severe
impacts on aquatic habitats. Specific problems with recreation were
noted in the Upper Gila River, and Tonto and Webber Creeks (Voeltz
2002). For example, Voeltz (2002) noted that in-channel vehicular
traffic was a threat to headwater chubs in Tonto Creek (also discussed
above under Roads). Much of the current range of the headwater chub
occurs on public lands administered by the U.S. Forest Service, and
public use of these lands is high; such use creates an elevated risk of
human-caused impacts such as off-road vehicle use.
Development activities. Headwater chub habitat is also threatened
increasingly from urban and suburban development (Tellman et al. 1997).
Urban and suburban development affects headwater chub and its habitat
in a number of ways, such as direct alteration of streambanks and
floodplains from construction of buildings, gardens, pastures, and
roads (Tellman et al. 1997), or as mentioned above, diversion of water,
both from streams and connected groundwater (Glennon 1995). On a
broader scale, urban and suburban development alters the watershed,
which changes the hydrology, sediment regimes, and pollution input
(Dunne and Leopold 1978; Horak 1989; Medina 1990; Reid 1993; Waters
1995). In addition, it has been documented that the introduction of
nonnative plants and animals, such as releases from home aquariums,
that can adversely affect headwater chub become more likely as nearby
human populations increase (Aquatic Nuisance Species Task Force 1994).
Suburban and urban development have degraded and eliminated
headwater chub habitat. The Phoenix metropolitan area, founded in part
due to its proximity to the Salt and Gila Rivers, is a population
center of 3.5 million people. Communities in the middle and upper Verde
River watershed, such as the Prescott-Chino Valley, the Cottonwood-
Clarkdale-Camp Verde communities, Strawberry, Pine, and Payson, are all
seeing rapid population growth. Many of these communities are near
headwater chub populations, and 25 percent of known headwater chub
populations occur in areas of urban and commercial development (Voeltz
2002). On a broader scale, as of 2005, Arizona was listed as the second
fastest in Statewide population growth in the nation, and Arizona is
projected to grow by 109 percent by the year 2030 (U.S. Census Bureau
2005).
Human activities in the watershed have had substantial adverse
impacts to headwater chub habitat. Watershed alteration is a cumulative
result of many human uses, including timber harvest, livestock grazing,
roads, recreation, channelization, and residential development. The
combined effect of all of these actions results in a substantial loss
and degradation of habitat (Burns 1971; Reid 1993). For example, in
Williamson Valley Wash, human uses (e.g., recreational use of off-road
vehicles) in the highly erodible upper watershed have resulted in
increased erosion and high loads of sediment. In 1993, flooding in
Williamson Valley Wash carried enough sediment that the isolated pool
where Gila chub (Gila intermedia), a related species to the headwater
chub, were previously collected became completely filled with sand and
gravel (Weedman et al. 1996).
Factor B: Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
We do not believe that overutilization is a threat to headwater
chub in Arizona because angler catch is considered light (J. Warnecke,
Arizona Game and Fish Department, pers. comm. 2004). However, in the
upper Gila River in New Mexico, there are reports of anglers
purposefully discarding chub species, which may be having a negative
effect on populations of headwater chub locally (Voeltz 2002).
Factor C: Disease or Predation
Nonnative fish that prey on and/or compete with headwater chub are
a serious and persistent threat to the continued existence of this
species. Direct predation by nonnative fishes on, and competition of
nonnative fishes with, the headwater chub has resulted in rangewide
population declines and local extirpations (e.g., Christopher Creek,
Rye Creek, and Horton Creek). Nonnative aquatic organisms negatively
affect native fish through predation, aggression and harassment,
resource competition, habitat alteration, aquatic community disruption,
introduction of diseases and parasites, and hybridization (numerous
citations; see U.S. Fish and Wildlife Service (2001)). Based on survey
information, nonnative species occur in every known population of
headwater chub (Voeltz 2002).
Headwater chub evolved in a fish community with low species
diversity and where few predators existed, and as a result developed
few or no mechanisms to deal with predation (Carlson and Muth 1989). In
its habitats, the headwater chub was probably the most predatory fish
and experienced little or no competition. Nonnative fishes known from
within the historical range of headwater chub in the Gila River basin
include channel catfish (Ictalurus punctatus), flathead catfish
(Pylodictis olivaris), red shiner (Cyprinella lutrensis), fathead
minnow (Pimephales promelas), green sunfish (Lepomis cyanellus),
largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus
dolomieui), rainbow trout (Oncorynchus mykiss), western mosquitofish
(Gambusia affinis), carp (Cyprinus carpo), warmouth (Lepomis gulosus),
bluegill (Lepomis macrochiris), yellow bullhead (Ameiurus natalis),
black bullhead (Ameiurus melas), and goldfish (Carassius auratus)
(Arizona Game and Fish Department Heritage Data Management System, U.S.
Fish and Wildlife Service 2001).
The introduction and spread of nonnative species has long been
identified as one of the major factors in the continuing decline of
native fishes throughout North America and particularly in the
southwest (Miller 1961; Lachner et al. 1970; Ono et al. 1983; Minckley
and Deacon 1991; Carlson and Muth 1989; Cohen and Carlton 1995; Fuller
et al. 1999). In the American southwest, Miller et al. (1989) concluded
that introduced nonnatives were a causal factor in 68 percent of the
fish extinctions in North America in the last 100 years. For 70 percent
of those
[[Page 26015]]
fish still extant, but considered to be endangered or threatened,
introduced nonnative species are a primary cause of the decline
(Aquatic Nuisance Species Task Force 1994; Lassuy 1995). In Arizona,
release or dispersal of new nonnative aquatic organisms is a continuing
phenomenon (Rosen et al. 1995; U.S. Fish and Wildlife Service 2001).
Introduction of nonnative species has also been consistently cited as a
threat to the native fish fauna of the Colorado River, and is listed as
a factor in the listing rules of nine other fish species with
historical ranges that overlap with headwater chub (bonytail (Gila
elegans) (45 FR 27710), humpback chub (Gila cypha) (32 FR 4001), Gila
chub (67 FR 51948), Colorado pikeminnow (Ptychocheilus lucius) (32 FR
4001), spikedace (Meda fulgida) and loach minnow (Tiaroga cobitis),( 51
FR 23769), razorback sucker (Xyrauchen texanus) (56 FR 54957), desert
pupfish (Cyprinodon macularius) (61 FR 10842), and Gila topminnow
(Poecilopsis occidentalis) (32 FR 4001)). In the Gila River basin,
introduction of nonnatives is considered a major factor in the decline
of all native fish species (Minckley 1985; Williams et al. 1985;
Minckley and Deacon 1991).
Aquatic nonnative species are introduced and spread into new areas
through a variety of mechanisms, both intentional and accidental, and
authorized and unauthorized. Mechanisms for nonnative dispersal in the
southwestern United States include inter-basin water transfer, sport
stocking, aquaculture, aquarium releases, bait-bucket release (release
of fish used as bait by anglers), and for use in biological control
(U.S. Fish and Wildlife Service 2001).
Dudley and Matter (2000) found that nonnative green sunfish prey
on, compete with, and virtually eliminate recruitment of Gila chub (a
recently federally listed species that is closely related to headwater
chub) in Sabino Creek in Arizona. Similar effects of green sunfish on
Gila chub have been documented in Silver Creek in Arizona (Unmack et
al. 2003). In the Verde River, Bonar et al. (2004) found that
largemouth bass, smallmouth bass, bluegill, green sunfish, channel
catfish, flathead catfish, and yellow bullhead all consumed native
fish. Roundtail chub (a closely related species to headwater chub) have
been found in stomachs of largemouth bass in the lower Salt River (P.
Unmack, Arizona State University, pers. comm. 2004). Bestgen and Propst
(1989) reported that, of nonnatives present in New Mexico, smallmouth
bass, flathead catfish, and channel catfish most impacted headwater
chub via predation.
Nonnative crayfish also appear to prey on and compete with all life
stages of Gila chub (Carpenter 2000, 2005), a fish species closely
related to headwater chub. At least two species of crayfish
(Procambaris clarki and Orconectes virilis) have been introduced into
Arizona aquatic systems and one or both species co-occur with headwater
chub in at least four streams. Crayfish are considered a cause of
decline for one population of headwater chub, and are documented as
having contributed to the extirpation of two of its populations (Voeltz
2002).
Disease, and especially parasites, are a threat. Asian tapeworm
(Bothriocephalus acheilognathi) was introduced into the United States
via imported grass carp in the early 1970s. It has since become well-
established in the southeast and mid-south and has been recently found
in the southwest. The definitive host in the life cycle of B.
acheilognathi is cyprinid fishes, and, therefore, it is a potential
threat to the headwater chub as well as to the other native fishes in
Arizona. The Asian tapeworm affects fish health in several ways. Two
direct impacts are by impeding the digestion of food as it passes
through the intestinal track, and when large numbers of worms feed off
of the fish they can cause emaciation and starvation. The Asian
tapeworm is present in the Colorado River basin in the Virgin River
(Heckman et al. 1986) and the Little Colorado River (Clarkson et al.
1997). It has recently invaded the Gila River basin and was found
during the fall 1998 Central Arizona Project (CAP) monitoring in the
Gila River near Ashurst-Hayden Dam.
Anchor worm (Lernaea cyprinacea) (Copepoda), an external parasite,
is unusual in that it has little host specificity, infecting a wide
range of fishes and amphibians. Severe Lernaea sp. infections have been
noted in a number of chub populations. Hendrickson (1993) noted very
high infections of Lernaea sp. during warm periods in the Verde River,
and Voeltz (2002) reported that headwater chubs found in Gun Creek in
2000, when surface flow was almost totally lacking, ``showed signs of
stress, and many had Lernaea, black grub, lesions and an unidentified
fungus.'' Increases in infection negatively affect headwater chub
populations with Girmendonk and Young (1997) concluding that
``parasitic infestations may greatly affect the health and thus
population size of native fishes.''
Factor D: The Inadequacy of Existing Regulatory Mechanisms
There are currently no specific Federal protections for headwater
chub, and generalized Federal protections found in Forest plans, Clean
Water Act dredge and fill regulations for streams, and other statutory,
regulatory, or policy provisions have not been shown to be effective in
preventing the decline of this species. Presently, Federal, State, and
Tribal statutes, regulations, and planning have not achieved
significant conservation of headwater chub and its habitat.
As described above, introductions of nonnative fish are likely a
significant threat to headwater chub. Fish introductions are illegal
unless approved by the respective States. However, enforcement is
difficult. Many nonnative fish populations are established through
illegal introductions. Nine species of fish, crayfish, and waterdogs
(tiger salamanders (Ambystoma pigrimum)) may be legally used as bait in
Arizona, all of which are nonnative to the State of Arizona and several
of which are known to have serious adverse effects on native species.
The portion of the State in which use of live bait is permitted is
limited, and use of live bait is restricted in much of the Gila River
system in Arizona (Arizona Game and Fish Department 2004). New Mexico
allows use of live bait-fish (New Mexico Game and Fish Department
2004). Live bait use of two species of sunfish and all ``minnows'' are
allowed. Goldfish (Carassius auratus), a nonnative formerly allowed for
live bait use, is no longer allowed. Arizona and New Mexico also
continue to stock nonnative fishes within areas that are connected to
habitat of headwater chub.
Increasing restrictions of live bait use will reduce the input of
nonnative species into headwater chub habitat. However, it will do
little to reduce unauthorized bait use or other forms of ``bait-
bucket'' transfer (e.g., dumping of unwanted aquarium fish, which may
be invasive nonnative species) not directly related to bait use. In
fact, those other ``bait-bucket'' transfers are expected to increase as
the human population of Arizona increases and as nonnative species
remain available to the public through aquaculture and the aquarium
trade. The general public has been known to dump unwanted pet fish and
other aquatic species into irrigation ditches such as the CAP aqueduct
in the Phoenix metropolitan area (U.S. Fish and Wildlife Service 2001).
The Arizona Game and Fish Department also regulates species of
[[Page 26016]]
nonnatives that can legally be brought into the State. Prohibited
nonnative species are put onto the Restricted Live Wildlife List
(Commission Order 12-4-406). However, species are allowed unless they
are prohibited by placement on the list, rather than the more
conservative approach of prohibited unless specifically allowed, and
this leaves a serious regulatory inadequacy that allows the opportunity
for many noxious nonnatives to be legally imported and introduced into
Arizona. New Mexico has adopted a more stringent approach; no live
animal (except domesticated animals or domesticated fowl or fish from
government hatcheries) is allowed to be imported without a permit (NMS
17-3-32). However, the majority of the headwater chub range occurs
within Arizona.
The Federal Land Policy Management Act of 1976 (43 U.S.C. 1701 et
seq.) and the National Forest Management Act of 1976 (16 U.S.C. 1600 et
seq.) direct Federal agencies to prepare programmatic-level management
plans to guide long-term resource management decisions. In addition,
the U.S. Forest Service is required to manage habitat to maintain
viable populations of existing native and desired nonnative vertebrate
species in planning areas (36 CFR 219.19). The Forest Service is the
largest landowner and manager of headwater chub habitat. The Forest
Service lists the headwater chub as a sensitive species in the lower
Colorado River basin in the southwestern region (Arizona and New
Mexico). However, a sensitive species designation provides little
protection to the headwater chub because it only requires the Forest
Service to analyze the effects of their actions on sensitive species,
but does not require that they choose environmentally benign actions.
Voeltz (2002) found that livestock grazing occurred in every drainage
in which headwater chub occur and he considered this land use an
ongoing threat. Most of these areas where the majority of extant
populations of headwater chub occur are managed by the Forest Service.
Wetland values and water quality of aquatic sites inhabited by the
headwater chub are afforded varying protection under the Federal Water
Pollution Control Act of 1948 (33 U.S.C. 1251-1376), as amended;
Federal Executive Orders 11988 (Floodplain Management) and 11990
(Protection of Wetlands); and section 404 of the Clean Water Act, which
regulates dredging and filling activities in waterways.
The New Mexico Department of Game and Fish has adopted a wetland
protection policy whereby the Department does not endorse any project
that would result in a net decrease in either wetland acreage or
wetland habitat values. This policy may afford some protection to
headwater chub habitat, although it is advisory only and destruction or
alteration of wetlands is not regulated by State law.
The State of Arizona Executive Order Number 89-16 (Streams and
Riparian Resources), signed on June 10, 1989, directs State agencies to
evaluate their actions and implement changes, as appropriate, to allow
for restoration of riparian resources. At this time, we have no
monitoring information on the effects of this Executive Order, nor do
we have information indicating that actions taken under it have been
effective in reducing adverse effects to the headwater chub.
The National Environmental Policy Act of 1969 (NEPA) (42 U.S.C.
4321-4347) requires Federal agencies to consider the environmental
impacts of their actions. Most actions taken by the Forest Service and
other Federal agencies that affect the headwater chub are subject to
NEPA. NEPA requires Federal agencies to describe the proposed action,
consider alternatives, identify and disclose potential environmental
impacts of each alternative, and involve the public in the decision-
making process. However, Federal agencies are not required to select
the alternative having the least significant environmental impacts. A
Federal action agency may select an action that will adversely affect
sensitive species provided that these effects were known and identified
in a NEPA document.
Status of headwater chub on Tribal lands is not well known. Any
regulatory or other protective measures for the species on Tribal lands
would be at the discretion of the individual Tribe and non-Tribal
entities would not likely be privy to information on the adequacy of
such measures. The San Carlos Apache Tribe has developed a fisheries
management plan that provides protection to headwater chub; however,
there are only two populations of the species that occur on San Carlos
Apache lands.
The State of New Mexico is seeking to add the headwater chub as an
endangered species under its Wildlife Conservation Act, which prohibits
take (New Mexico Wildlife Conservation Act 17-2-41(B)). Unlike the
Federal Act, however, habitat destruction does not constitute take
under New Mexico's law. The Arizona Game and Fish Department has
created a draft conservation agreement and strategy for several native
Arizona fishes including headwater chub. These efforts are not yet
complete. AGFD has also implemented conservation actions that have
benefited the species, including assisting with restoration of
headwater chub habitat in Fossil Creek. We are working with both
Arizona and New Mexico to ensure that these efforts will be as
effective as possible. However, at this time, these efforts are not
finalized, no funding has been committed to ensure their execution, and
their future effectiveness is uncertain. We will evaluate these efforts
using the guidelines developed in our Policy for Evaluation of
Conservation Efforts When Making Listing Decisions (PECE) (68 FR 15100;
March 28, 2003).
Factor E: Other Natural or Manmade Factors Affecting Its Continued
Existence
The rarity of headwater chub increases its extinction risk
associated with stochastic events such as drought, flood, and wildfire.
Headwater chub populations have been fragmented and isolated to smaller
stream segments and are thus vulnerable to natural or manmade factors
(e.g., drought, groundwater pumping) that might further reduce their
population sizes. Headwater chub are not considered secure in any of
the stream segments where they occur (Voeltz 2002). In general, Arizona
is an arid state; about one-half of Arizona receives less than 10
inches of rain a year. As described above in factor A, dewatering and
other forms of habitat loss have resulted in fragmentation of headwater
chub populations, and water demands from a rapidly increasing human
population could further reduce habitat available to these species, and
further fragment populations. In examining the relationship between
species distribution and extinction risk in southwestern fishes, Fagan
et al. (2002) found that the number of occurrences or populations of a
species is less significant a factor in determining extinction risk
than is habitat fragmentation. Fragmentation of habitat makes the
headwater chub vulnerable to extinction from threats of further habitat
loss and competition from nonnative fish and other threats because
immigration and recolonization from adjacent populations is not likely.
Thus, the risk of extinction of this species, based on their degree of
fragmentation alone, is high and is predicted to increase with
increasing fragmentation and rarity (Fagan et al. 2002).
The probability of catastrophic stochastic events that could
eliminate isolated populations of this species is
[[Page 26017]]
exacerbated by a century of livestock grazing and fire suppression that
has led to unnaturally high fuel loadings (Cooper 1960; Covington and
Moore 1994; Swetnam and Baison 1994; Touchan et al. 1995; White 1985).
We have information indicating that the intensity of forest fires has
increased in recent times (Covington and Moore 1994; National
Interagency Fire Center 2006). Fires in the Southwest frequently occur
during the summer monsoon season. As a result, fires are often followed
by rain that washes ash-laden debris into streams (Rinne 2004). Extreme
summer fires, such as the 1990 Dude Fire, and corresponding ash flows
have decimated some fish populations including headwater chub
populations in the East Verde River (Voeltz 2002). Recently, several
extreme summer fires, including the 2002 Rodeo-Chedeski Fire and the
2004 Willow Fire, have resulted in significant losses of individuals
and populations of headwater chub throughout Arizona (A. Robinson,
Arizona Game and Fish Department, pers. comm. 2005). Carter and Rinne
(unpubl. data) found that the Picture Fire both benefited and
eliminated headwater chub from portions of Spring Creek. The fire
eliminated chubs from Turkey Creek, a tributary to Spring Creek. In
other parts of Spring Creek, however, chubs initially declined but
later thrived after the fire, presumably because most of the nonnative
fishes were eliminated. Every extant population of headwater chub is at
risk of experiencing effects from wildfire.
Finding
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the headwater chub. We reviewed the petition, information
available in our files, other published and unpublished information
submitted to us during the public comment period following our 90-day
petition finding, and consulted with recognized headwater chub experts
and other Federal and State resource agencies. On the basis of the best
scientific and commercial information available, we find that proposing
to list the headwater chub throughout its range is warranted, but that
immediate proposal of a regulation implementing this action is
precluded by higher priority listing actions, and progress is being
made to add or remove qualified species from the Lists of Endangered
and Threatened Wildlife and Plants.
In making this finding, we recognize that there have been declines
in the distribution and abundance of the headwater chub, primarily
attributed to the introduction and subsequent predation by, and
competition with, nonnative fishes, as documented in a large body of
scientific research (Miller 1961; Minckley 1973; Bestgen and Propst
1989; Miller et al. 1989; Minkley and Deacon 1991; Creef and Clarkson
1993; Bonar et al. 2004), as well as declines resulting from a host of
land uses that have dewatered and degraded the species' habitats
(Miller 1961; Miller 1972; Minckley 1973; Deacon et al. 1979; Bestgen
and Propst 1989; Bezzerides and Bestgen 2002; Voeltz 2002). Direct
predation and competition of nonnative fishes on the headwater chub has
resulted in rangewide population declines and local extirpations (e.g.,
Christopher Creek, Rye Creek, and Horton Creek). Because we have found
that nonnative species are present in every remaining population of
this species, we conclude that all remaining populations are at risk of
declines and extirpation as a result of predation by nonnative species.
Furthermore, all remaining populations are fragmented and isolated,
making them vulnerable to further declines and local extirpations from
other factors, as discussed in detail above and outlined in Table 2
above (Fagan et al. 2002). Populations that go extinct following
habitat fragmentation are unlikely to be recolonized due to the
isolation from, and lack of, habitat connectivity to potential source
populations.
The isolation of remaining headwater chub populations and habitat
fragmentation as a result of nonnative fish introductions and habitat
alteration have made remaining populations vulnerable to extinction
from random events such as parasites and stochastic events (Fagan et
al. 2002). Stochastic events, such as fire, have only recently been
recognized as an important factor in the decline of this species (Rinne
2004). We believe that fire will continue to be a factor in the decline
of this species (National Interagency Fire Center 2006; www.nifc.gov).
Other factors include parasitism and the inadequacy of existing
regulatory mechanisms. These factors have contributed to declines or
extirpations of headwater chub.
We conclude that the overall magnitude of threats to the headwater
chub is high, and that the overall immediacy of these threats is
imminent. While we conclude that listing the headwater chub is
warranted, an immediate proposal to list this species is precluded by
other higher priority listing actions. At the present time there are
over 280 species that we regard as candidates for addition to the Lists
of Endangered and Threatened Wildlife and Plants, 95 of which have the
same listing priority as the headwater chub. During fiscal year (FY)
2006, almost our entire national listing budget will be consumed by
work on various listing actions to comply with court orders and court-
approved settlement agreements; to meet statutory deadlines for
petition finding or listing determinations; to evaluate and determine
emergency listing; and to complete essential litigation-related,
administrative, and program management tasks.
The headwater chub will be added to the list of candidate species
upon publication of this 12-month finding. We will continue to monitor
the status of this species as new information becomes available. This
review will determine if a change in status is warranted, including the
need to make prompt use of emergency listing procedures.
We have reviewed the available information to determine if the
existing and foreseeable threats pose an emergency. We have determined
that an emergency listing is not warranted for this species at this
time because a number of populations exist, and some of these appear to
be stable at the current time. However, if at any time we determine
that emergency listing of the headwater chub is warranted, we will seek
to initiate an emergency listing.
We intend that any proposed listing action for these fish species
will be as accurate as possible. Therefore, we will continue to accept
additional information and comments from all concerned governmental
agencies, the scientific community, industry, or any other interested
party concerning this finding.
References Cited
A complete list of all references cited herein is available upon
request from the Field Supervisor at the Arizona Ecological Services
Office (see ADDRESSES section).
Author
The primary author of this document is the Arizona Ecological
Services Office (see ADDRESSES section).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: April 27, 2006.
H. Dale Hall,
Director, Fish and Wildlife Service.
[FR Doc. E6-6648 Filed 5-2-06; 8:45 am]
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