[Federal Register Volume 60, Number 141 (Monday, July 24, 1995)]
[Proposed Rules]
[Pages 37866-37868]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-18046]



=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AD22


Endangered and Threatened Wildlife and Plants; Proposed Change 
from Subspecies to Vertebrate Population Segment for Virgin River Chub 
in Virgin River and Notice of Status Review for Virgin River Chub in 
Muddy River

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule and notice of status review.

-----------------------------------------------------------------------

SUMMARY: Recent taxonomic work concluded that specific rank is 
warranted for the Virgin River chub (Gila robusta seminuda = G. 
seminuda), a federally endangered species found in the Virgin River 
system of Arizona, Nevada, and Utah. Moreover, these researchers 
concluded that the chub in the Muddy (= Moapa) River of Nevada, is 
conspecific with the Virgin River chub. Previously this distinctive 

[[Page 37867]]
population of Virgin River chub, a category 2 candidate for Federal 
listing, was considered a separate, unnamed subspecies of roundtail 
chub (G. robusta), and was referred to as the Moapa roundtail chub.
    Because of this recent taxonomic work, the U.S. Fish and Wildlife 
Service (Service) accepts that specific rank is warranted for the 
Virgin River chub and proposes to change the listing of the Virgin 
River chub in the Virgin River from a subspecies to a vertebrate 
population segment in the List of Endangered and Threatened Wildlife. 
In addition, the Service hereby initiates a status review of the Virgin 
River chub in the Muddy River to determine whether this vertebrate 
population segment warrants listing as a threatened or endangered 
species under the Endangered Species Act of 1973, as amended (Act).

DATES: Comments from all interested parties must be received by 
September 22, 1995. Public hearing requests must be received by 
September 7, 1995.

ADDRESSES: Comments and materials concerning this proposal and notice 
should be sent to Mr. Carlos H. Mendoza, Acting State Supervisor, U.S. 
Fish and Wildlife Service, 4600 Kietzke Lane, Building C-125, Reno, 
Nevada 89502-5093 (facsimile: 702-784-5870). Comments and materials 
received will be available for public inspection, by appointment, 
during normal business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Selena Werdon, Fish and Wildlife 
Biologist, at the above address (telephone: 702-784-5227).

SUPPLEMENTARY INFORMATION:

Background

    Discovered in the early 1870's, the Virgin River chub was described 
by Edward Drinker Cope and Harry Crecy Yarrow as a full species, Gila 
seminuda, in 1875. Later, Max M. Ellis (1914) considered the Virgin 
River chub to be intermediate between the roundtail chub (G. robusta) 
and bonytail chub (G. elegans), and reduced the fish to a subspecies of 
roundtail chub (G. robusta seminuda). The fish was believed to be 
restricted to the Virgin River between Hurricane, Utah, and its 
confluence with the Colorado River.
    In a recent taxonomic study of Gila using morphological and genetic 
characters, DeMarais and others (1992) concluded that the prior 
treatment of the Virgin River chub as a subspecies of the roundtail 
chub was inappropriate and arbitrary. The authors asserted that 
specific rank is warranted for G. seminuda, which likely arose through 
introgressive hybridization involving G. robusta and G. elegans 
(DeMarais et al. 1992). Moreover, DeMarais et al. (1992) included the 
chub in the Muddy River, a Virgin River tributary, within G. seminuda. 
These conclusions were accepted by the American Fisheries Society and 
the American Society of Ichthyologists and Herpetologists Fish Names 
Committee (Joseph S. Nelson, in litt., 1993). The Service also accepts 
these conclusions.
    The Service and other authorities (Holden and Stalnaker 1970, 
Minckley 1973, Smith et al. 1977) have treated the chubs within the 
Muddy River as a separate, unnamed subspecies of roundtail chub (= 
Moapa roundtail chub). The Service also has considered this chub to be 
a category 2 candidate for Federal listing since 1982 (47 FR 58455, 54 
FR 556, 56 FR 58804, and 59 FR 58982). Category 2 species are taxa for 
which information now in the possession of the Service indicates that 
proposing to list as endangered or threatened is possibly appropriate, 
but for which sufficient data on biological vulnerability and threat 
are not currently available to support proposed rules. Though 
genetically allied to the chub within the Virgin River and apparently 
of hybrid origin, the Muddy River population of G. seminuda is 
``distinctive'' (DeMarais et al. 1992; Bruce DeMarais, pers. comm. June 
29, 1994). Moreover, despite access to Lake Mead, no migration between 
the Virgin River and Muddy River populations has been verified (Allan 
and Roden 1978). As a result of the distinctiveness and reproductive 
isolation of the two populations, the Service concludes that the Virgin 
River chub consists of two vertebrate population segments.
    The decline of chub in the Muddy River was first documented in the 
1960's (Wilson et al. 1966, Deacon and Bradley 1972). By 1964, the 
abundance of chub at a 1938 collection site had decreased more than 83 
percent; a similar decrease (approximately 92 percent) was documented 
at a 1942 collection site (Wilson et al. 1966). Between 1964 and 1968, 
Deacon and Bradley (1972) noted an upstream shift in the distribution 
of the Muddy River population. By 1974-1975, the chub had been 
completely eliminated from the lower Muddy River and were further 
reduced in abundance in the middle portion of the river (Cross 1976). 
The decline may have been related to cumulative effects of parasitism 
(Wilson et al. 1966), changes in flow, water quality, and substrate 
(Deacon and Bradley 1972, Cross 1976), channelization (Cross 1976), and 
the establishment of nonnative fish species (Deacon et al. 1964, Hubbs 
and Deacon 1964, Deacon and Bradley 1972, Cross 1976).
    The Service has carefully assessed the best scientific and 
commercial information available regarding the Virgin River population 
of Virgin River chub in determining to propose this rule. Based on this 
evaluation and especially recent taxonomic work, the preferred action 
is to change the listing of the Virgin River chub in the Virgin River 
in the List of Endangered and Threatened Wildlife (50 CFR 17.11(h)) 
from an endangered subspecies throughout its entire range to an 
endangered vertebrate population segment in the Virgin River in Utah, 
Arizona, and Nevada. As a result, the Virgin River chub in the Virgin 
River will remain listed as endangered in the same area as it was prior 
to this taxonomic work, while the Virgin River chub in the Muddy River 
will remain unlisted. In addition, the Service hereby initiates a 
status review of the Virgin River chub in the Muddy River to determine 
whether this population segment warrants listing as threatened or 
endangered under the Act. The limited information and data currently 
available to the Service indicate that the chub in the Muddy River 
remain reduced in abundance from historical levels, and that the 
species has been eliminated from the lower Muddy River. This decline is 
likely a result of a combination of habitat degradation, interactions 
with nonnative species, and parasitism.

Public Comments Solicited
    The Service intends that any final action resulting from this 
proposal or that any listing proposal eventually resulting from this 
notice be as accurate and effective as possible. Therefore, comments or 
suggestions from the public, other concerned governmental agencies, the 
scientific community, industry, private interests, or any other 
interested party concerning any aspect of this proposed rule and notice 
are hereby solicited. Comments particularly are sought concerning:
    (1) Biological, commercial trade, or other relevant data concerning 
any threat (or lack thereof) to Virgin River chub in the Muddy River;
    (2) The location of any additional populations of the species and 
the reasons why any habitat should or should not be determined to be 
critical habitat as provided by section 4 of the Act;
    (3) Additional information concerning the range, distribution, and 
population size of the Muddy River population segment; 

[[Page 37868]]

    (4) Current or planned activities in the Moapa Valley and their 
possible impacts on the species;
    (5) Additional information concerning the taxonomy of Virgin River 
chub; and
    (6) Data on chub movement (or lack thereof) between the Virgin and 
Muddy Rivers.
    Final promulgation of the regulation changing the Virgin River chub 
from a subspecies to a population listing will take into consideration 
the comments and any additional information received by the Service, 
and such communications may lead to a final regulation that differs 
from this proposal. In addition, the Service will use the best 
available scientific and commercial data to evaluate the status of the 
Muddy River population segment and, if deemed appropriate, prepare a 
listing proposal. If listing is deemed warranted, the Service will 
publish a proposed rule in the Federal Register for public comment and 
will include a review of materials used in its preparation. Critical 
habitat will be addressed in any proposed rule.
    The Endangered Species Act provides for a public hearing on this 
proposal, if requested. Requests must be received by September 7, 1995. 
Such requests must be made in writing (includes FAX) and addressed to 
the Acting State Supervisor, U.S. Fish and Wildlife Service (see 
ADDRESSES action).

National Environmental Policy Act

    The Service has determined that an Environmental Assessment, as 
defined under the authority of the National Environmental Policy Act of 
1969, need not be prepared in connection with regulations adopted 
pursuant to section 4(a) of the Endangered Species Act of 1973, as 
amended. A notice outlining the Service's reasons for this 
determination was published in the Federal Register on October 25, 1983 
(48 FR 49244).

References Cited

    A complete list of all references cited herein, as well as others, 
is available upon request from the office listed in the ADDRESSES 
section above.

Author

    The primary author of this notice is Selena Werdon (see ADDRESSES).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, and Transportation.

Proposed Regulation Promulgation

    Accordingly, the Service hereby proposes to amend part 17, 
subchapter B of chapter I, title 50 of the Code of Federal Regulations, 
as set forth below:

PART 17--[AMENDED]

    1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

    2. Section 17.11(h) is amended by revising the entry for ``Chub, 
Virgin River'' under FISHES to read as follows:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                      Species                                                    Vertebrate population                                                  
----------------------------------------------------      Historic range          where endangered or      Status    When listed   Critical     Special 
       Common name              Scientific name                                       threatened                                    habitat      rules  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
          Fishes                                                                                                                                        
                                                                                                                                                        
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
Chub, Virgin River.......  Gila seminuda (=G.        U.S.A. (AZ, NV, UT).....  Virgin River............  E                  361,  NA          NA        
                            robusta seminuda).                                                                                                          
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dated: March 22, 1995.
Mollie H. Beattie,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 95-18046 Filed 7-21-95; 8:45 am]
BILLING CODE 4310-55-P