Endangered and Threatened Wildlife and Plants; 90-Day 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, 39981-39986 [05-13315]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 70, Number 132 (Tuesday, July 12, 2005)]
[Proposed Rules]
[Pages 39981-39986]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-13315]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 90-Day 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 90-day petition finding and initiation of status 
review.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list a distinct population segment 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). We find 
that the petition presented substantial scientific and commercial data 
indicating that these listings may be warranted. Therefore, we are 
initiating a status review to determine if listing these species is 
warranted. To ensure that the status review is comprehensive, we are 
soliciting scientific and commercial information regarding these 
species. The petition also asked the Service to designate critical 
habitat for these species. The Act does not allow petitions for 
designation of critical habitat. However, any determinations on 
critical habitat will be made if and when a listing action is initiated 
for these species.

DATES: The finding announced in this document was made on June 30, 
2005. To be considered in the 12-month finding for this petition, 
comments and information should be submitted to us by September 12, 
2005.

ADDRESSES: Data, information, comments, or questions concerning this 
petition and our finding should be submitted to the Field Supervisor, 
Arizona Ecological Services Office, 2321 West Royal Palm Drive, Suite 
103, Phoenix, Arizona. The petition, supporting data, and comments will 
be available for public inspection, by appointment, during normal 
business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, 
Arizona Ecological Services Office at the above address (telephone 602-
242-0210; facsimile 602-242-2513).

SUPPLEMENTARY INFORMATION:

Public Information Solicited

    When we make a finding that substantial information is presented to 
indicate that listing a species may be warranted, we are required to 
promptly commence a review of the status of the species. To ensure that 
the status review is complete and based on the best available 
scientific and commercial information, we are soliciting information on 
the roundtail and headwater chubs. We request any additional 
information, comments, and suggestions from the public, other concerned 
governmental agencies, Tribes, the scientific community, industry, or 
any other interested parties concerning the status of the roundtail and 
headwater chubs. We are seeking information regarding the two species' 
historical and current status and distribution, their biology and 
ecology, ongoing conservation measures for the species and their 
habitat, and threats to the species and their habitat.
    If you wish to comment or provide information, you may submit your 
comments and materials concerning this finding to the Field Supervisor 
(see ADDRESSES).
    Our practice is to make comments and materials provided, including 
names and home addresses of respondents, available for public review 
during regular business hours. Respondents may request that we withhold 
a respondent's identity, to the extent allowable by law. If you wish us 
to withhold your name or address, you must state this request 
prominently at the beginning of your submission. However, we will not 
consider anonymous comments. To the extent consistent with applicable 
law, we will make all submissions from organizations or businesses, and 
from individuals identifying themselves as representatives or officials 
of organizations or businesses, available for public inspection in 
their entirety. Comments and materials received will be available for 
public inspection, by appointment, during normal business hours at the 
address provided under ADDRESSES.

Background

    Section 4(b)(3)(A) of the Endangered Species Act of 1973, as 
amended (16 U.S.C. 1531 et seq.) (Act), requires that we make a finding 
on whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information indicating that the 
petitioned action may be warranted. We are to base this finding on all 
information available to us at the time we make the finding. To the 
maximum extent practicable, we are to make this finding within 90 days 
of our receipt of the petition, and publish our notice of this finding 
promptly in the Federal Register.
    Our standard for substantial information within the Code of Federal 
Regulations (CFR) with regard to a 90-day petition finding is ``that 
amount of information that would lead a reasonable person to believe 
that the measure proposed in the petition may be warranted'' (50 CFR 
424.14(b)). If we find that substantial information was presented, we 
are required to promptly commence a review of the status of the 
species.
    In making this finding, we relied on information provided by the 
petitioners and evaluated that information in accordance with 50 CFR 
424.14(b). Our process of coming to a 90-day finding under section 
4(b)(3)(A) of the Act and section 424.14(b) of our regulations is 
limited to a determination of whether

[[Page 39982]]

the information in the petition meets the ``substantial information'' 
threshold.
    We do not conduct additional research at this point, nor do we 
subject the petition to rigorous critical review. Rather, as the Act 
and regulations contemplate, in coming to a 90-day finding, we accept 
the petitioner's sources and characterizations of the information 
unless we have specific information to the contrary.
    Our finding considers whether the petition states a reasonable case 
for listing on its face. Thus, our finding expresses no view as to the 
ultimate issue of whether the species should be listed. We reach a 
conclusion on that issue only after a more thorough review of the 
species' status. In that review, which will take approximately 9 
months, we will perform a rigorous, critical analysis of the best 
available scientific and commercial information, not just the 
information in the petition. We will ensure that the data used to make 
our determination as to the status of the species is consistent with 
the Act and the Information Quality Act (44 U.S.C. 3504(d)(1) and 3516 
note).

Petition

    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 critical habitat be designated 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 distinct population 
segment 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 
signed and adopted by the District Court for the District of Arizona on 
May 5, 2005. This notice constitutes our 90-day 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, pursuant to the Court's order.

Biology and Distribution

    The general background information provided in this section below 
is based on information in the petition and in our files.
    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 first described roundtail chub from specimens 
collected from the Zuni River in northeastern Arizona and northwestern 
New Mexico (Baird and Girard 1853). Headwater chub was first described 
from Ash Creek and the San Carlos River in east-central Arizona in 1874 
(Cope and Yarrow 1875). The taxonomy of these two species has undergone 
numerous revisions (see Miller 1945; Holden 1968; Rinne 1969; Holden 
and Stalnaker 1970; Rinne 1976; Smith et al. 1977; DeMarais 1986; 
Rosenfeld and Wilkinson 1989; DeMarais 1992; Dowling and DeMarais 1993; 
Douglas et al. 1998; Minckley and DeMarais 2000; Gerber et al. 2001); 
however, both are now recognized as distinct species (Minckley and 
DeMarais 2000; Nelson et al. 2004). A summary of the taxonomic history 
can be found in Voeltz (2002).
    The historical distribution of headwater and roundtail chub in the 
lower Colorado River basin is poorly documented, due to the paucity of 
early collections and the widespread anthropogenic (manmade) changes to 
aquatic ecosystems beginning in the mid 19th century [i.e., habitat 
alteration and nonnative species introductions (Girmendonk and Young 
1997)]. Both of these species were historically considered common 
throughout their respective ranges (Minckley 1973; Holden and Stalnaker 
1975; Propst 1999). Voeltz (2002) estimated historical distribution 
based on museum collection records, agency database searches, 
literature searches, and discussion with biologists.
    Roundtail chub in the lower Colorado River basin was historically 
found in (1) the Gila and Zuni Rivers in New Mexico and (2) the Black, 
Colorado, Little Colorado, Bill Williams, Gila, San Francisco, San 
Carlos, San Pedro, Salt, Verde, White, and Zuni Rivers in Arizona, as 
well as in numerous tributaries within those basins. Voeltz (2002) 
estimated the lower Colorado River basin roundtail chub historically 
occupied approximately 4,500 kilometers (km) [2,796 miles (mi)] of 
rivers and streams in Arizona and New Mexico. A form that until 
recently was considered to be the roundtail chub outside the Colorado 
River basin in Mexico is now considered a different species, Gila 
minacae (S. Norris, California State University Channel Islands, pers. 
comm. 2004).
    Roundtail chub in the lower Colorado River basin in Arizona 
currently occurs in two tributaries of the Little Colorado River 
(Chevelon and East Clear Creeks); several tributaries of the Bill 
Williams River basin (Boulder, Burro, Conger, Francis, Kirkland, 
Sycamore, and Trout Creeks); the Salt River and two of its tributaries 
(Cherry Creek and Salome Creek); the Verde River and four of its 
tributaries (Fossil, Oak, West Clear, and Wet Beaver Creeks); Aravaipa 
Creek; and in New Mexico, in the upper Gila River (Voeltz 2002).
    Roundtail chub in the Lower Colorado River basin are found in cool 
to warm waters of mid-elevation rivers and streams, and often occupy 
the deepest pools and eddies of large streams (Minckley 1973; Brouder 
et al. 2000; Minckley and DeMarais 2000; Bezzerides and Bestgen 2002). 
Although roundtail chub are often associated with various cover 
features, such as boulders, vegetation, and undercut banks, they are 
less apt to use cover than congeneric species (of the same genus) such 
as the headwater chub and Gila chub (Gila intermedia) (Minckley and 
DeMarais 2000). Water temperatures for the species vary between 14[deg] 
and 24[deg] Celsius (C) (57[deg] and 75[deg] Fahrenheit (F)); spawning 
has been documented at 18[deg]

[[Page 39983]]

and 22[deg] C (64[deg] and 72[deg] F) (Bestgen 1985; Kaeding et al. 
1990; Brouder et al. 2000). Spawning occurs from February through June 
in pool, run, and riffle habitats, with slow to moderate water 
velocities (Neve 1976; Bestgen 1985; Propst 1999; Brouder et al. 2000). 
Roundtail chub are omnivores, consuming aquatic and terrestrial 
invertebrates, aquatic vegetation, detritus, and occasionally 
vertebrates (Propst 1999; Schreiber and Micnkley 1981).
    Historically, 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, headwater chub currently occur in 
four tributaries of the Verde River (Fossil Creek, the East Verde 
River, Wet Bottom Creek, and Deadman Creek); Tonto Creek and eight of 
its tributaries (Buzzard Roost, Gordon, Gun, Haigler, Horton, Marsh, 
Rock and Spring Creeks); and in New Mexico, in the upper East Fork, 
lower Middle Fork, and lower West Forks of the Gila River (Voeltz 
2002). Headwater chub also appear to have been documented recently in 
the San Carlos River drainage, though their status in that system is 
unknown (Minckley and DeMarais 2000; Voeltz 2002).
    Headwater chub occur in the middle to upper reaches of moderately 
sized streams (Minckley and DeMarais 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 vary between 20[deg] to 27[deg] C (68[deg] and 
81[deg] F), and minimum water temperatures were around 7[deg] C 
(45[deg] F) (Bestgen and Propst 1989; Barrett and Maughan 1994). 
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 (minute aquatic crustaceans), and 
plant material.

Previous Federal Actions

    We placed the headwater chub (as G. r. grahami) on the list of 
candidate species as a category 2 species on December 30, 1982 (47 FR 
58454). Category 2 species were those for which existing information 
indicated that listing was possibly appropriate, but for which 
substantial supporting biological data to prepare a proposed rule were 
lacking. On January 6, 1989, the roundtail chub (as G. robusta, which 
at that time included headwater chub) was placed into category 2 (54 FR 
554). Due to lack of funding to gather existing information on these 
fishes, both species remained as category 2 candidate species through 
the 1991 (56 FR 58804; November 21, 1991) and 1994 (59 FR 58982; 
November 15, 1994) Candidate Notices of Review. In the 1996 Candidate 
Notice of Review (61 FR 7596; February 28, 1996), the use of category 2 
candidates was discontinued, and the roundtail and headwater chub were 
no longer recognized as candidates.

Distinct Vertebrate Population Segment

    The petitioners have asked us to consider designating a DPS for the 
roundtail chub in the lower Colorado River basin. Under the Act, we 
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 entitled Policy 
Regarding the Recognition of Distinct Vertebrate Population (61 FR 
4721; February 7, 1996) (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. 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. These are applied similarly for 
addition to the lists of endangered and threatened wildlife and plants, 
for reclassification, and for removal. 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 DPS 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 allows an entity given 
DPS status under the Act to be adequately defined and described in some 
way that distinguishes it from other representatives of its species. A 
population segment of a vertebrate species may be considered discrete 
if it satisfies either one of the following two conditions: (1) it is 
markedly separated from other populations of the same taxon as a 
consequence of physical, physiological, ecological, or behavioral 
factors. Quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation; or (2) it is 
delimited by international governmental boundaries within which 
significant differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms exist.

Information Provided in the Petition

    The petitioners state that the roundtail chub meets the standard 
for discreteness because populations in the upper and lower Colorado 
River basins appear to have been separate in historical times, and this 
is supported by current information from molecular investigations.
    The historical range of roundtail chub included both the upper and 
lower Colorado River basins in the States of Wyoming, Utah, Colorado, 
New Mexico, Arizona, and Nevada, and likely Baja California and Sonora, 
Mexico (Propst 1999; Bezzerides and Bestgen 2002; Voeltz 2002). 
Currently this species occurs in the upper basin in Wyoming, Utah, and 
Colorado. In the lower basin it currently occurs in New Mexico and 
Arizona. The petitioners maintain that, although the populations in the 
upper and lower Colorado River basins were presumed to have intermixed 
with each other in the mainstem Colorado River, historical collections 
and genetic evidence show that there were and are, in fact two discrete 
populations, one in each basin.
    Further, the petitioners cite Bezzerides and Bestgen (2002), who 
concluded that, historically, the distribution of roundtail chub was 
continuous in the Colorado River basin

[[Page 39984]]

via the mainstem Colorado River, although they found that two discrete 
population centers were evident, one in each of the lower and upper 
basins. Although early surveys were infrequent, only four records of 
roundtail chub are documented in the mainstem Colorado River between 
the two basins (Voeltz 2002). Based on this information, Minckley 
(1979) and C.O. Minckley (1996) considered roundtail chub rare in the 
Colorado River mainstem. Thus, the petitioners conclude that the 
historical situation of roundtail chub in the Colorado River basin 
appears to be that there were two population centers, one each in the 
upper and lower basins, likely with very little mixing.
    The petitioners argue that discreteness of the populations of 
roundtail chub in each basin also appears to be supported by molecular 
investigations. Allozymes and mitochondrial DNA (mtDNA) sequence 
variation of roundtail chub in the two basins are significantly 
different (DeMarais 1992; Dowling and DeMarais 1993; Minckley and 
DeMarais 2000; Gerber et al. 2001). Further, the petitioners note that 
Gerber et al. (2001) found that mtDNA of lower basin roundtail chub was 
entirely absent from roundtail chub in the upper basin.

Significance

    Under our DPS policy, in addition to our consideration that a 
population segment is discrete, we consider its biological and 
ecological significance to the taxon to which it belongs, within the 
context that the DPS policy be used ``sparingly'' while encouraging the 
conservation of genetic diversity (61 FR 4721; February 7, 1996). This 
consideration may include, but is not limited to, evidence of the 
persistence of the discrete population segment in an ecological setting 
that is unique for the taxon; evidence that loss of the population 
segment would result in a significant gap in the range of the taxon; 
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 historical range; and evidence that 
the discrete population segment differs markedly from other populations 
of the species in its genetic characteristics.

Information Provided in the Petition

    The petitioners maintain that roundtail chub in the lower Colorado 
River basin should be considered significant under our DPS policy for 
several reasons. They state that roundtail chub in the lower basin 
occur in an ecological setting unique for the species based on 
differences in various ecoregion variables, such as hydrograph, 
sediment, substrate, nutrient flow, cover, and water chemistry (Burkham 
1970; Sellers 1974; Carlson and Muth 1989; Miller and Hubert 1990; 
Minckley and Rinne 1991; Leopold 1994; Bailey 1995; Rosgen 1996). The 
petitioners maintain that loss of the lower Colorado River DPS of 
roundtail chub would result in a significant gap in the range of the 
taxon because this population segment constitutes a majority of the 
species' range in two states (Arizona and New Mexico) and all of 
several major river systems, including the Little Colorado, Bill 
Williams, and Gila River basins. They also cite data that indicate the 
lower Colorado River population of roundtail chub is significant in 
that it differs markedly from other populations of the species in its 
genetic characteristics. As mentioned above, they note that allozymes 
and mitochondrial DNA (mtDNA) sequence variation of roundtail chub in 
the two basins are significantly different (DeMarais 1992; Dowling and 
DeMarais 1993; Minckley and Demarais 2000; Gerber et al. 2001), and 
cite that Gerber et al. (2001) found that mtDNA of lower basin 
roundtail chub was entirely absent from roundtail chub in the upper 
basin. Based on this information, the petitioners argue that the lower 
Colorado River roundtail chub population offers unique opportunities to 
uncover scientific information available through study of its unique 
evolutionary trajectory. The petitioners also argue that there are 
differences in status and management needs between the populations in 
the two basins (the upper basin has fewer people; has less extreme 
threats to aquatic habitats, in part because there is more water and 
less demand for water; and has more significant Federal programs in 
place to protect and recover native fishes).

Evaluation of Information in the Petition

    Based on the data presented in the petition, there appears to be 
substantial scientific information that roundtail chub populations in 
the lower Colorado River warrant further review of whether they are 
discrete from the rest of the species' range and that they may be 
significant to the taxon as a whole, as defined in our DPS policy.
    According to our DPS policy, if a population of species if found to 
be both discrete and significant, we then evaluate the conservation 
status of the population in relation to the listing factors found in 
section 4(a)(1) of the Act. Our assessment of the conservation status 
of the population of the roundtail chub in the lower Colorado River 
basin based on the information provided in the petition is provided in 
the ``Discussion'' section below.

Discussion

    In the following discussion, we discuss each of the major 
assertions made in the petition, organized by the listing factors found 
in section 4(a)(1) of the Act. Section 4 of the Act and its 
implementing regulations (50 CFR 424) set forth the procedures for 
adding species to the Federal list of endangered and threatened 
species. A species may be determined to be an endangered or threatened 
species if it is threatened by one or more of the five factors 
described in section 4(a)(1) of the Act and meets either the definition 
of endangered or threatened pursuant to section 3 of the Act. The five 
listing factors are: (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.
    This 90-day finding is not a status assessment of either species 
and does not constitute a status review under the Act. The discussion 
presents information provided in the petition related to the factors 
used for evaluation of listing pursuant to section 4(a)(1) of the Act 
for both species, the population of the roundtail chub in the Lower 
Colorado River Basin and the headwater chub.

A. Present or Threatened Destruction, Modification, or Curtailment of 
the Species' Habitat or Range

Geographic Range and Status

Information Provided in the Petition
    The petitioners claim that the decline of the roundtail chub was 
noted as early as 1961 (Miller 1961), and that recent status reviews of 
both headwater and roundtail chub (Bestgen 1985; Girmendonk and Young 
1997; Bezzarides and Bestgen 2002; Voeltz 2002) led our Desert Fishes 
Recovery team to recommend that both species be listed as endangered on 
numerous occasions. They also cite the recent Arizona Game and Fish 
Department (Voeltz 2002) review of these species, which found declines 
from historical levels and indicated that many of the remaining 
populations were vulnerable to extirpation from various threats. Of the 
40 recently documented populations of roundtail chub in the lower 
Colorado River basin, Voeltz (2002) found that 6

[[Page 39985]]

were stable-threatened, 13 were unstable-threatened, 10 were 
extirpated, and 11 populations were of unknown status. Voeltz (2002) 
considered a population stable if the species was abundant or common 
and data over 5-10 years indicated a recruiting population; secure if 
no obvious threats were apparent; and threatened if nonnative aquatic 
species were present or serious current or future habitat-altering land 
or water uses were identified.
    Of the 19 recently documented populations of headwater chub, Voeltz 
(2002) found that 6 were stable-threatened, 6 were unstable-threatened, 
1 was stable-secure, 3 were extirpated, and 3 populations were of 
unknown status. Deadman Creek, the one population that Voeltz 
considered stable-secure, has since been invaded by nonnative green 
sunfish (Lepomis cyanellus); thus that population should now be 
considered stable-threatened (Voeltz, Arizona Game and Fish Department, 
pers. comm. 2003).

Habitat

Information Provided in the Petition
    The petitioners state that roundtail and headwater chub are 
threatened by a variety of actions: livestock grazing, water 
withdrawal, dam and dam operation, roads and logging, recreation, 
mining, urban development, channelization, and the cumulative effects 
of these actions. The petitioners contend that habitat in substantial 
portions of the range of these species has been significantly altered 
by these factors, and they contend that remaining areas known to be 
occupied by roundtail and headwater chub are threatened by additional 
loss and degradation of habitat (Minckley 1985; Bestgen and Propst 
1989; Bezzerides and Bestgen 2002; Tellman et al. 1997; Voeltz 2002).
Summary of Habitat Threats and Evaluation of Information in the 
Petition
    The petitioners have provided substantial scientific information 
that a variety of anthropogenic activities that affect the habitat of 
roundtail and headwater chub in the lower Colorado River basin either 
singly or in combination with one another, may be destroying or 
modifying roundtail and headwater chub habitat.

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

Information Provided in the Petition

    The petitioners do not provide information suggesting that 
overutilization for commercial, recreational, scientific, or 
educational purposes is a threat to either the roundtail or headwater 
chubs; however, they do consider overutilization in their analysis of 
the inadequacy of existing regulatory mechanisms and in their analysis 
of recreation as form of habitat loss.

Evaluation of Information in the Petition

    Our response to these issues is included within those sections of 
our analysis.

C. Disease or Predation

Information Provided in the Petition

    The petitioners contend that nonnative fish that compete with and/
or prey on roundtail and headwater chub are a serious and persistent 
threat to the continued existence of these species (U.S. Fish and 
Wildlife Service 1999 a, b, 2001a, b), and they cite a number of 
examples of nonnative fish species negatively affecting native fish 
populations. They also claim that largemouth bass, smallmouth bass, 
green sunfish, flathead catfish, channel catfish, black bullhead 
(Ameiurus melas), and yellow bullhead are all known or suspected to 
prey on native fish and are to some degree sympatric (occupying the 
same or overlapping geographic areas without interbreeding) with either 
roundtail or headwater chub (Girmendonk and Young 1997; Voeltz 2002).
    The petitioners contend that most streams within the range of the 
roundtail and headwater chub contain multiple nonnative species (U.S. 
Fish and Wildlife Service 2001a and b), and that aquatic nonnative 
species continue to be introduced into streams in Arizona, likely 
through a variety of mechanisms, both intentional and accidental, that 
include interbasin water transfer, sport stocking, aquaculture, 
aquarium releases, bait-bucket release (release of fish used as bait by 
anglers), and biological control (Rosen et al. 1995; U.S. Fish and 
Wildlife Service 2001). The petitioners note that nonnatives are 
present and considered a threat to remnant populations of roundtail or 
headwater chub in 28 of the 30 streams in which they occur (Voeltz 
2002).
    The petitioners also contend that disease, and especially 
parasites, may be a threat and cite the following information. 
Roundtail and headwater chub have been found to be infected by a number 
of parasites, including protozoans (Ichthyophthirius multifiliis), 
trematodes (Ornithodiplostomum ptychocheilus, Clinostomum marginatum, 
and Plagioporus species), cestodes (Isoglaridacris bulboocirrus), 
nematodes (Dacnitoides species, Rhabdochona decaturensis, and 
Rhabdochona species), and anchor worms (Lernaea species) (Girmendonk 
and Young 1997; James 1968; Mpoame 1981; Voeltz 2002).

Evaluation of Information in the Petition

    The petition provides substantial scientific information that 
predation and disease is a factor that may threaten the continued 
existence of the roundtail and headwater chubs.

D. Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition

    The petitioners state that there are at present no specific Federal 
protections for roundtail or 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 been inadequate to check the rapid decline of these two 
fishes. The petitioners cite Doremus and Pagel (2001) who found that 
State, local, and private laws and regulations were of substantially 
less effectiveness at conservation of imperiled species than the Act 
and concluded that ``Background law generally does not protect species 
against either of these two primary threats (habitat degradation and 
exotic species). Even the Act provides little protection against exotic 
species, but it does provide the strongest currently available 
protection against habitat degradation.'' The petitioners review a 
substantial body of Federal, State, and Tribal statutes, regulations, 
and planning work against conservation of roundtail and headwater chubs 
and their habitat, and contend that these also indicate the plight of 
roundtail and headwater chub can be remedied only through Federal 
listing under the Act.
    As an example, the petitioners examined management on 58 U.S. 
Forest Service allotments with known roundtail or headwater chub 
populations and contend that the agency failed to consider the effects 
of livestock grazing on these species on 23 allotments, and that 
livestock grazing was considered to potentially impact these species or 
their habitat on 20 of the other 35; in two of these cases the U.S. 
Forest Service concluded that grazing would ``eventually trend the 
species toward federal listing.'' They also contend that of the 58 
allotments that contained these species, poor riparian and watershed 
conditions were

[[Page 39986]]

found on 40 of the 58 allotments, and only four allotments were noted 
as having healthy riparian conditions.

Evaluation of Information in the Petition

    The petition provides substantial information that relates to the 
inadequacies of existing regulatory mechanisms to address significant 
threats to roundtail and headwater chub throughout their range.

E. Other Natural or Manmade Factors Affecting the Species' Continued 
Existence

Information Provided in the Petition

    The petitioners contend that the probability of catastrophic 
stochastic (random) events is exacerbated by a century of livestock 
grazing and fire suppression that have led to unnaturally high fuel 
loadings (Cooper 1960; Covington and Moore 1994; Swetnam and Baison 
1994; Touchan et al. 1995; White 1985). Forests that once frequently 
burned at low intensities now rarely burn, but when they do, it is 
often at stand-replacing intensity (Covington and Moore 1994). 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 1996). It is such debris, rather than the fires 
themselves, that impacts and/or devastates fish populations. For 
example, the petition states that the 1990 Dude Fire was known to 
severely impact fish in the East Verde River. Voeltz (2002) states: 
``Fish populations within the East Verde drainage were heavily impacted 
following the Dude Fire in 1990. Runoff from storms following the fire 
washed ash and sediments off of the burned slopes into the system, 
reducing or eliminating fish populations in many of the small tributary 
streams in the area of the fire.''
    The petitioners also maintain that extensive human alteration of 
watersheds that has occurred over the past 150 years in the lower 
Colorado River basin has resulted in changes in the hydrologic regimes 
of the rivers and in the geomorphology of the river channels. This 
human-initiated change is exacerbated by the naturally highly variable 
climate of the area. Peaks of flood flows have increased in volume 
while moving through the system more rapidly, so that damaging floods 
have become more frequent and more destructive. This increase in 
destruction is also tied to removal of riparian vegetation and 
encroachment of agricultural fields and buildings upon the floodplain. 
Because of the reduced distribution and isolation of remaining 
roundtail and headwater chub populations in combination with increased 
severity of fire and altered hydrologic regimes, the petitioners argue 
that both species are at risk of extinction independent of any other 
factors, such as nonnative fish or habitat degradation.

Evaluation of Information in the Petition

    The petition provides substantial scientific information that 
illustrates the severity of the threat of stochastic events to rare and 
fragmented populations, and includes research conducted specifically in 
the southwest, and on a suite of fishes including roundtail and 
headwater chubs (Fagan et al. 2002).

Finding

    We have reviewed the petition and literature cited in the petition, 
and we have evaluated that information in relation to other pertinent 
literature and information available in our files. On the basis of our 
review, we find that the petition presents substantial scientific 
information indicating that listing the roundtail chub as a distinct 
population segment in the lower Colorado River basin, and the headwater 
chub throughout its range, may be warranted.
    We have reviewed the available information to determine if the 
existing and foreseeable threats pose an emergency. We have determined 
that emergency listing is not warranted for these species at this time, 
because of the overall number of extant populations and the fact that 
some of these appear to be stable at the current time. However, if at 
any time we determine that emergency listing of the roundtail or 
headwater chub are warranted, we will seek to initiate an emergency 
listing.
    The petitioners also request that critical habitat be designated 
for this species. We always consider the need for critical habitat 
designation when listing species. If we determine in our 12-month 
finding that listing the roundtail and headwater chub is warranted, we 
will address the designation of critical habitat at the time of the 
proposed rulemaking.

References Cited

    A complete list of all references cited herein is available upon 
request from the Field Supervisor (see ADDRESSES section).

Author

    The primary authors of this document are staff at 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: June 30, 2005.
Matt Hogan,
Acting Director, Fish and Wildlife Service.
[FR Doc. 05-13315 Filed 7-11-05; 8:45 am]
BILLING CODE 4310-55-P