Endangered and Threatened Wildlife and Plants; Proposed Rule to Designate Critical Habitat for the Spikedace (Meda fulgida, 75546-75590 [05-23999]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 70, Number 243 (Tuesday, December 20, 2005)]
[Proposed Rules]
[Pages 75546-75590]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-23999]



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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Proposed Rule to 
Designate Critical Habitat for the Spikedace (Meda fulgida) and the 
Loach Minnow (Tiaroga cobitis); Proposed Rule

Federal Register / Vol. 70, No. 243 / Tuesday, December 20, 2005 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU33


Endangered and Threatened Wildlife and Plants; Proposed Rule to 
Designate Critical Habitat for the Spikedace (Meda fulgida) and the 
Loach Minnow (Tiaroga cobitis)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
designate a total of approximately 633 river miles (mi) (1018.7 
kilometers (km)) of critical habitat for spikedace and loach minnow. 
Proposed critical habitat is located in New Mexico and Arizona. We 
hereby solicit data and comments from the public on all aspects of this 
proposal, including data on economic and other impacts of the 
designation. We may revise this proposal prior to final designation to 
incorporate or address new information received during public comment 
periods.

DATES: We will accept comments from all interested parties until 
February 21, 2006. We must receive requests for public hearings in 
writing at the address shown in the ADDRESSES section by February 3, 
2006.

ADDRESSES: If you wish to comment, you may submit your comments and 
materials concerning this proposal, identified by RIN number 1018-AU33, 
by any one of several methods:
    1. You may submit written comments and information to Steve 
Spangle, Field Supervisor, U.S. Fish and Wildlife Service, Arizona 
Ecological Services Office, 2321 West Royal Palm Road, Suite 103, 
Phoenix, Arizona, 85021.
    2. You may hand-deliver written comments and information to our 
Arizona Ecological Services Office, or fax your comments to 602/242-
2513.
    3. You may send your comments by electronic mail (e-mail) to SD--
LMComments@fws.gov. For directions on how to submit electronic filing 
of comments, see the ``Public Comments Solicited'' section.
    (4) Federal eRulemaking Portal: https://www.regulations.gov. Follow 
the instructions for submitting comments.
    All comments and materials received, as well as supporting 
documentation used in preparation of this proposed rule, 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 (telephone 602/242-0210; facsimile 
602/242-2513).

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    It is our intent that any final action resulting from this proposal 
will be as accurate and effective as possible. Therefore, we solicit 
comments or suggestions from the public, other concerned governmental 
agencies, the scientific community, industry, or any other interested 
party concerning this proposed rule. On the basis of public comment, 
during the development of the final rule we may find that areas 
proposed do not contain features essential to the conservation of the 
species, are appropriate for exclusion under section 4(b)(2), or not 
appropriate for exclusion, and in all of these cases, this information 
would be incorporated into the final designation. We particularly seek 
comments concerning:
    (1) The reasons why any areas should or should not be determined to 
be critical habitat as provided by section 4 of the Act, including 
whether the benefits of designation will outweigh the benefits of 
excluding areas from the designation.
    (2) Specific information on the distribution and abundance of 
spikedace and loach minnow and their habitats, and which habitat 
contains the primary constituent elements essential to the conservation 
of these species and why.
    (3) Land-use designations and current or planned activities in or 
adjacent to the areas proposed and their possible impacts on proposed 
critical habitat.
    (4) Any foreseeable economic, national security, or other potential 
impacts resulting from the proposed designation, in particular, any 
impacts on small entities.
    (5) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    (6) In addition, please consider the following: We specifically 
solicit the delivery of spikedace- and loach minnow-specific management 
plans including implementation schedules for areas included in this 
proposed designation, and comment on: (a) Whether these areas are 
occupied and contain the primary constituent elements that are 
essential to the conservation of the species; (b) whether these areas 
warrant exclusion; and (c) the basis for excluding these areas from 
critical habitat pursuant to section 4(b)(2) of the Act.
    (7) We are not proposing the upper portion of the San Pedro River 
as critical habitat because of the presence of nonnative fish species 
and the absence of both spikedace and loach minnow. We seek comment on 
whether this area is essential to the conservation of the species and 
whether it should be included as critical habitat.
    (8) Some of the lands we have identified as containing features 
essential to the conservation of the spikedace and loach minnow are 
being considered for exclusion from the final designation of critical 
habitat. We specifically solicit comment on the possible inclusion or 
exclusion of such areas;
    (a) Whether these areas are occupied and contain the features 
essential to the conservation of the species and;
    (b) Whether these, or other areas proposed but not specifically 
addressed in this proposal, warrant exclusion and;
    (9) We are not proposing Fossil Creek as critical habitat because 
it is currently unoccupied. However, we seek comment on whether this 
area is essential to the conservation of the species and whether it 
should be included as critical habitat.
    If you wish to comment, you may submit your comments and materials 
concerning this proposal by any one of several methods (see ADDRESSES 
section above). Please submit electronic comments in ASCII file format 
and avoid the use of special characters or any form of encryption. 
Please also include ``Attn: spikedace/loach minnow'' in your e-mail 
subject header and your name and return address in the body of your 
message. If you do not receive a confirmation from the system that we 
have received your Internet message, contact us directly by calling our 
Arizona Ecological Services Office at 602/242-0210. Please note that 
the e-mail address, SD--LMComments@fws.gov, will be closed at the 
termination of the public comment period.
    Our practice is to make comments, including names and addresses of 
respondents, available for public review during regular business hours. 
Individual respondents may request that we withhold their home 
addresses from the administrative record, which we will honor to the 
extent allowable by law. There also may be circumstances in which we 
would withhold from the rulemaking record a respondent's identity, as 
allowable by law. If you wish us to withhold your name and/or address, 
you must state this

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prominently at the beginning of your comments. However, we will not 
consider anonymous comments. 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 above address.

Designation of Critical Habitat Provides Little Additional Protection 
to Species

    In 30 years of implementing the Act, the Service has found that the 
designation of statutory critical habitat provides little additional 
protection to most listed species, while consuming significant amounts 
of conservation resources. The Service's present system for designating 
critical habitat is driven by litigation rather than biology, limits 
our ability to fully evaluate the science involved, consumes enormous 
agency resources, and imposes huge social and economic costs. The 
Service believes that additional agency discretion would allow our 
focus to return to those actions that provide the greatest benefit to 
the species most in need of protection.

Role of Critical Habitat in Actual Practice of Administering and 
Implementing the Act

    While attention to and protection of habitat is paramount to 
successful conservation actions, we have consistently found that, in 
most circumstances, the designation of critical habitat is of little 
additional value for most listed species, yet it consumes large amounts 
of conservation resources. Sidle (1987) stated, ``Because the ESA can 
protect species with and without critical habitat designation, critical 
habitat designation may be redundant to the other consultation 
requirements of section 7.'' Currently, only 470 species, or 38 
percent, of the 1,253 listed species in the United States under the 
jurisdiction of the Service have designated critical habitat.
    We address the habitat needs of all 1,253 listed species through 
conservation mechanisms such as listing, section 7 consultations, the 
section 4 recovery planning process, the section 9 protective 
prohibitions of unauthorized take, section 6 funding to the states, and 
the section 10 incidental take permit process. The Service believes 
that it is these measures that may make the difference between 
extinction and survival for many species.
    We note, however, that the August 6, 2004 Ninth Circuit judicial 
opinion, (Gifford Pinchot Task Force v. United States Fish and Wildlife 
Service) found our definition of adverse modification was invalid. In 
response to the decision, the Director has provided guidance to the 
Service based on the statutory language. In this rule, our analysis of 
the consequences and relative costs and benefits of the critical 
habitat designation is based on application of the statute consistent 
with the 9th Circuit's ruling and the Director's guidance.

Procedural and Resource Difficulties in Designating Critical Habitat

    We have been inundated with lawsuits for our failure to designate 
critical habitat, and we face a growing number of lawsuits challenging 
critical habitat determinations once they are made. These lawsuits have 
subjected the Service to an ever-increasing series of court orders and 
court-approved settlement agreements, compliance with which now 
consumes nearly the entire listing program budget. This leaves the 
Service with little ability to prioritize its activities to direct 
scarce listing resources to the listing program actions with the most 
biologically urgent species conservation needs.
    The consequence of the critical habitat litigation activity is that 
limited listing funds are used to defend active lawsuits, to respond to 
Notices of Intent (NOIs) to sue relative to critical habitat, and to 
comply with the growing number of adverse court orders. As a result, 
listing petition responses, the Service's own proposals to list 
critically imperiled species, and final listing determinations on 
existing proposals are all significantly delayed.
    The accelerated schedules of court-ordered designations have left 
the Service with almost no ability to provide for adequate public 
participation or to ensure a defect-free rulemaking process before 
making decisions on listing and critical habitat proposals due to the 
risks associated with noncompliance with judicially imposed deadlines. 
This in turn fosters a second round of litigation in which those who 
fear adverse impacts from critical habitat designations challenge those 
designations. The cycle of litigation appears endless, is very 
expensive, and in the final analysis provides little additional 
protection to listed species.
    The costs resulting from the designation include legal costs, the 
cost of preparation and publication of the designation, the analysis of 
the economic effects and the cost of requesting and responding to 
public comment, and in some cases the costs of compliance with the 
National Environmental Policy Act (NEPA). None of these costs result in 
any benefit to the species that is not already afforded by the 
protections of the Act enumerated earlier, and they directly reduce the 
funds available for direct and tangible conservation actions.

Background

    It is our intent to discuss only those topics directly relevant to 
the designation of critical habitat in this proposed rule. For more 
information on the spikedace and loach minnow, refer to the final 
designation of critical habitat for the spikedace and loach minnow 
published in the Federal Register on April 25, 2000 (65 FR 24328).

Previous Federal Actions

    On September 20, 1999, the United States District Court for the 
District of New Mexico, Southwest Center for Biological Diversity v. 
Clark, CIV 98-0769 M/JHG, ordered us to finalize a designation of 
critical habitat for the spikedace and loach minnow by February 17, 
2000. On October 6, 1999, the court amended the order to require us to 
propose a critical habitat determination rather than requiring a final 
designation. We published our proposed rule to designate critical 
habitat in the Federal Register on December 10, 1999 (64 FR 69324). On 
December 22, 1999, the court extended the deadline to complete our 
determination until April 21, 2000. We published a final critical 
habitat designation on April 25, 2000 (65 FR 24329).
    In New Mexico Cattle Growers' Association and Coalition of Arizona/
New Mexico Counties for Stable Economic Growth v. United States Fish 
and Wildlife Service, CIV 02-0199 JB/LCS (D.N.M), the Plaintiffs 
challenged the April 25, 2000, critical habitat designation for the 
spikedace and loach minnow because the economic analysis had been 
prepared using the same methods which the Tenth Circuit had held to be 
invalid. The Center for Biological Diversity joined the lawsuit as a 
Defendant-Intervenor. The Service agreed to a voluntary vacatur of the 
critical habitat designation, except for the Tonto Creek Complex. On 
August 31, 2004, the United States District Court for the District of 
New Mexico set aside the April 25, 2000, critical habitat designation 
in its entirety and remanded it to the Service for preparation of a new 
proposed and final designation.

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Critical Habitat

    Critical habitat is defined in section 3 of the Act as--(i) the 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. ``Conservation'' means the use of all methods and 
procedures that are necessary to bring an endangered or a threatened 
species to the point at which listing under the Act is no longer 
necessary.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against destruction or adverse modification of 
critical habitat with regard to actions carried out, funded, or 
authorized by a Federal agency. Section 7 requires consultation on 
Federal actions that are likely to result in the destruction or adverse 
modification of critical habitat. The designation of critical habitat 
does not affect land ownership or establish a refuge, wilderness, 
reserve, preserve, or other conservation area. Such designation does 
not allow government or public access to private lands.
    To be included in a critical habitat designation, the habitat 
within the area occupied by the species must first have features that 
are essential to the conservation of the species. Critical habitat 
designations identify, to the extent known, using the best scientific 
data available, habitat areas that provide essential life cycle needs 
of the species (i.e., areas on which are found the primary constituent 
elements, as defined at 50 CFR 424.12(b)).
    Habitat occupied at the time of listing may be included in critical 
habitat only if the essential features therein may require special 
management or protection. When the best available scientific data do 
not demonstrate that the conservation needs of the species so require, 
we will not designate critical habitat in areas outside the 
geographical area occupied by the species at the time of listing. An 
area currently occupied by the species but that was not known to be 
occupied at the time of listing will likely be essential to the 
conservation of the species and, therefore, included in the critical 
habitat designation.
    The Service's Policy on Information Standards Under the Endangered 
Species Act, published in the Federal Register on July 1, 1994 (59 FR 
34271), and Section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658) 
and the associated Information Quality Guidelines issued by the Service 
provide criteria, establish procedures, and provide guidance to ensure 
that decisions made by the Service represent the best scientific data 
available. They require Service biologists to the extent consistent 
with the Act and with the use of the best scientific data available, to 
use primary and original sources of information as the basis for 
recommendations to designate critical habitat. When determining which 
areas are critical habitat, a primary source of information is 
generally the listing package for the species. Additional information 
sources include the recovery plan for the species, articles in peer-
reviewed journals, conservation plans developed by States and counties, 
scientific status surveys and studies, biological assessments, or other 
unpublished materials and expert opinion or personal knowledge. All 
information is used in accordance with the provisions of Section 515 of 
the Treasury and General Government Appropriations Act for Fiscal Year 
2001 (Pub. L. 106-554; H.R. 5658) and the associated Information 
Quality Guidelines issued by the Service.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Habitat is often 
dynamic, and species may move from one area to another over time. 
Furthermore, we recognize that designation of critical habitat may not 
include all of the habitat areas that may eventually be determined to 
be necessary for the recovery of the species. For these reasons, 
critical habitat designations do not signal that habitat outside the 
designation is unimportant or may not be required for recovery.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the Act and to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available information 
at the time of the action. Federally funded or permitted projects 
affecting listed species outside their designated critical habitat 
areas may still result in jeopardy findings in some cases. Similarly, 
critical habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans, or 
other species conservation planning efforts if new information 
available to these planning efforts calls for a different outcome.

Methods

    In determining areas that contain features essential to the 
conservation of spikedace and the loach minnow, we used the best 
scientific data available. We have reviewed the overall approach to the 
conservation of these species compiled in their respective recovery 
plans (USFWS 1991a, 1991b) and undertaken by local, State, Federal, and 
Tribal agencies, and private and non-governmental organizations 
operating within the species' range since their listing in 1986.
    We have also reviewed available information that pertains to the 
habitat requirements of these species. The material included data in 
reports submitted during section 7 consultations and by biologists 
holding section 10(a)(1)(A) recovery permits; research published in 
peer-reviewed articles, agency reports, and databases; and regional 
Geographic Information System (GIS) coverages and habitat models.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas to propose as critical 
habitat, we are required to base critical habitat determinations on the 
best scientific data available and to consider those physical and 
biological features (i.e., primary constituent elements (PCEs)) that 
are essential to the conservation of the species and that may require 
special management considerations or protection. These features include 
but are not limited to: Space for individual and population growth and 
for normal behavior; food, water, air, light, minerals or other 
nutritional or physiological requirements; cover or shelter; sites for 
breeding, reproduction, or rearing of offspring; and habitats that are 
protected from disturbance or are representative of the historical, 
geographical, and ecological distributions of a species.
    Each of the areas designated in this rule have been determined to 
contain sufficient PCEs to provide for one or more of the life history 
functions of spikedace or loach minnow. In some cases, the PCEs exist 
as a result of ongoing Federal actions. As a result, ongoing Federal 
actions at the time of designation will be included in the baseline in 
any consultation conducted subsequent to this designation.

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    We determined the primary constituent elements for spikedace and 
loach minnow from studies on their habitat requirements and population 
biology including, but not limited to, Barber et al. 1970, Minckley 
1973, Anderson 1978, Barber and Minckley 1983, Turner and Taffanelli 
1983, Barrett et al. 1985, Propst et al. 1986, Service 1989, Hardy et 
al. 1990, Douglas et al. 1994, Stefferud and Rinne 1996, and Velasco 
1997.

Lateral Extent

    The areas proposed for designation as critical habitat are designed 
to provide sufficient riverine and associated floodplain area for 
breeding, non-breeding, and dispersing adult spikedace and loach 
minnow, as well as for the habitat needs of juvenile and larval stages 
of these fishes. In general, the constituent elements of critical 
habitat for spikedace and loach minnow include the riverine ecosystem 
formed by the wetted channel and the adjacent floodplains within 300 
lateral feet on either side of bankfull stage. Spikedace and loach 
minnow use the riverine ecosystem for feeding, sheltering, and cover 
while breeding and migrating. This proposal takes into account the 
naturally dynamic nature of riverine systems and floodplains (including 
riparian and adjacent upland areas) that are an integral part of the 
stream ecosystem. For example, riparian areas are seasonally flooded 
habitats (i.e., wetlands) that are major contributors to a variety of 
vital functions within the associated stream channel (Federal 
Interagency Stream Restoration Working Group 1998, Brinson et al. 
1981). They are responsible for energy and nutrient cycling, filtering 
runoff, absorbing and gradually releasing floodwaters, recharging 
groundwater, maintaining streamflows, protecting stream banks from 
erosion, and providing shade and cover for fish and other aquatic 
species. Healthy riparian and adjacent upland areas help ensure water 
courses maintain the habitat components essential to aquatic species 
(e.g., see FS 1979; Middle Rio Grande Biological Interagency Team 1993; 
Briggs 1996), including the spikedace and loach minnow. Habitat quality 
within the mainstem river channels in the historical range of the 
spikedace and loach minnow is intrinsically related to the character of 
the floodplain and the associated tributaries, side channels, and 
backwater habitats that contribute to the key habitat features (e.g., 
substrate, water quality, and water quantity) in these reaches. We 
believe a relatively intact riparian area, along with periodic flooding 
in a relatively natural pattern, is important in maintaining the stream 
conditions necessary for long-term conservation of the spikedace and 
loach minnow.
    The lateral extent of streams was set at 300 ft (91.4 m) to either 
side of bankfull stage to accommodate stream meandering and high flows, 
and in order to ensure adequate protection of riparian zones adjacent 
to stream channels. Bankfull stage is defined as the discharge at which 
channel maintenance is the most effective, or the upper level of the 
range of channel-forming flows which transport the bulk of the 
available sediment over time. Bankfull stage is generally considered to 
be that level of stream discharge reached just before flows spill out 
onto the adjacent floodplain. The discharge that occurs at bankfull 
stage, in combination with the range of flows that occur over a length 
of time, govern the shape and size of the river channel (Rosgen 1996, 
Leopold 1997).
    The use of bankfull stage and 300 ft (91.4 m) on either side 
recognizes the naturally dynamic nature of riverine systems and 
recognizes that floodplains are an integral part of the stream 
ecosystem. The use of bankfull stage and 300 ft (91.4 m) on either side 
of a tributary also is an area that contains the features essential to 
the conservation of the species. A relatively intact floodplain, along 
with the periodic flooding in a relatively natural pattern, is an 
important element in the long-term survival and recovery of spikedace 
and loach minnow. The riparian areas encompassed in the 300 lateral 
feet (91.4 m) to either side of bankfull stage play an important role 
in overall stream health, in that they function as the floodplain and 
dissipate stream energies associated with high flows (BLM 1990). This 
is further discussed below in the ``Proposed Critical Habitat'' section 
of the rule.

Spikedace

    The specific primary constituent elements required of spikedace 
habitat are derived from the biological needs of the spikedace as 
described below.

Space for Individual and Population Growth and Normal Behavior

    Streams in the Southwestern United States have a wide fluctuation 
in flows and resulting habitat conditions at different times of the 
year. Spikedace persist in these varying conditions and, as discussed 
below, several studies have documented habitat conditions at occupied 
sites.

Habitat Preferences

    Spikedace have differing habitat requirements through their various 
life stages. Generally, adult spikedace prefer intermediate-sized 
streams with moderate to swift currents over sand, gravel, and cobble 
substrates (i.e. stream bottoms). Preferred water depths are less than 
11.8 in (30 cm) (Barber and Minckley 1966, Minckley 1973, Anderson 
1978, Rinne and Kroeger 1988, Hardy 1990, Sublette et al. 1990, Rinne 
1991, Rinne 1999a). As discussed below, larval and juvenile spikedace 
occupy different habitats than adults.
    Flow Velocities. Studies have been completed on the Gila River, 
Aravaipa Creek, and the Verde River. Measured flows in habitat occupied 
by adult spikedace ranged from 23.3 to 59.5 cm/second (9.2-23.4 in/
second) (Barber and Minckley 1966, Hardy 1990, Propst et al. 1986, 
Rinne 1991, Rinne 1991a, Rinne and Kroeger 1988, Schreiber 1978). 
Studies on the Gila River indicated that juvenile spikedace occupy 
areas with velocities of approximately 16.8 cm/second (6.6 in/second) 
while larval spikedace were found in velocities of 8.4 cm/second (3.3 
in/second) (Propst et al. 1986).
    Flow velocities in occupied habitats vary by season as well. During 
the warm season (June-November), spikedace on the Gila River occupied 
areas with mean flow velocities of 19.3 in/second (49.1 cm/second) at 
one site, and 7.4 in/second (18.8 cm/second) at the second site. During 
the cold season (December-May), mean flow velocities at these same 
sites were 15.5 in/second (39.4 cm/second) and 8.4 in/second (21.4 cm/
second). It is believed that spikedace seek areas in the stream that 
offer protection during periods of cooler temperatures to offset their 
decreased metabolic rates. Where water depth remains fairly constant 
throughout the year as at the first site, slower velocities provided 
habitats in portions of the stream with warmer temperatures. Where flow 
velocity remains fairly constant throughout the year, such as at the 
second site, shallower water provided habitats in portions of the 
stream with warmer temperatures (Propst et al. 1986).
    Larval and juvenile spikedace occupy different habitats than 
adults, tending to occupy shallow, peripheral portions of streams in 
areas with slower currents (Anderson 1978, Propst et al. 1986). Once 
they emerge from the gravel of the spawning riffles, spikedace larvae 
disperse to stream margins where water velocity is very slow or still. 
Slightly larger larvae were most commonly associated with slow-velocity 
water near

[[Page 75550]]

stream margins in areas where water depth was less than 12.6 inches 
(32.0 cm) (Propst et al. 1986). Juvenile spikedace (those fish 1.0 to 
1.4 in (25.4-35.6 mm) in length) occurred over a greater range of water 
velocities than larvae, but still in water depths of less than 12.6 in 
(32.0 cm). Juveniles and larvae are also occasionally found in quiet 
pools or backwaters lacking streamflow (Sublette et al. 1990).
    Outside of the breeding season, adult spikedace primarily use 
riffle habitat (a shallow area in a streambed causing ripples) or quiet 
eddies (where the water moves in the opposite direction of water in the 
main channel or in circular patterns) downstream of those riffles. 
Eighty percent of the spikedace collected in a Verde River study used 
run and glide habitat. For this study, a glide was defined as a portion 
of the stream with a lower gradient (0.3 percent), versus a run which 
had a slightly steeper gradient (0.3-0.5 percent) (Rinne and Stefferud 
1996). Spikedace on the Gila River were most commonly found in riffle 
areas of the stream with moderate to swift currents (Anderson 1978) and 
some run habitats (J.M. Montgomery 1985), as were spikedace in Aravaipa 
Creek (Barber and Minckley 1966).
    Seasonal differences in habitats utilized have been noted in the 
upper Gila drainage, for both the winter and breeding seasons. For 
example, the spikedace was found to use shallower habitats at 6.6 in 
(<16.8 cm) in the winter, and deeper water at 6.6 to 12.6 in (16.8-32.0 
cm) during warmer months (Propst et al. 1986, Sublette et al. 1990). 
During the breeding season, female and male spikedace become 
segregated, with females occupying deeper pools and eddies and males 
occupying riffles flowing over sand and gravel beds in water 
approximately 3.1 to 5.9 inches (7.9-15.0 cm) deep. Females then enter 
the riffles occupied by the males before ova are released into the 
water column (Barber et al. 1970).
    As noted above, streams in the Southwestern United States have a 
wide fluctuation in flows and are periodically dewatered. While 
portions of stream segments included in this designation may experience 
dry periods, they are still considered essential because the spikedace 
is adapted to this environment and will use these areas as connective 
corridors between occupied or seasonally occupied habitat when they are 
wetted.
    Substrates. Spikedace are known to occur in areas with low to 
moderate amounts of fine sediment and substrate embeddedness (filling 
in of spaces by fine sediments), which is essential for healthy 
development of eggs. Spawning has been observed in areas with sand and 
gravel beds and not in areas with fine sediment or substrate 
embeddedness, as described above. Additionally, low to moderate fine 
sediments ensure that eggs remain well-oxygenated and will not 
suffocate due to sediment deposition (Propst et al. 1986).
    In the Verde River study, spikedace glide-run habitats were 
characterized by approximately 29 percent sand or fines (silty sand) 
(Rinne 2001). Spikedace numbers in the Verde River increased almost 
three times (from 18 to 52 individuals) when the fine component of the 
substrate decreased from about 27 percent down to 7 percent (Neary et 
al. 1996), indicating that spikedace prefer habitats with lower amounts 
of fines. Sand content in all glide-run spikedace habitats in the Verde 
and Gila Rivers in 2000 was 18 and 20 percent (Rinne 2001).
    Larval spikedace substrate preferences are similar to those of 
adults. Sixty percent of spikedace larvae in the Gila River were found 
over sand-dominated substrates, while 18 percent were found over gravel 
and an additional 18 percent found over cobble-dominated substrates 
(Propst et al. 1986). While 45 percent of juvenile spikedace were found 
over sand substrates, an additional 45 percent of the juveniles were 
found over gravel substrates, with the remaining 9 percent associated 
with cobble-dominated substrates (Propst et al. 1986).
    The degree of substrate embeddedness may also affect the prey base 
for spikedace. As discussed below, mayflies constitute a significant 
portion of the spikedace diet. Suitable habitat for the type of 
mayflies found in Aravaipa Creek includes pebbles or gravel for 
clinging. Excess sedimentation would cover or blanket smaller pebbles 
and gravel, resulting in a lack of suitable habitat for mayflies, and a 
subsequent decrease in available prey items for spikedace.
    Flooding. Rainfall in the southwest is generally characterized as 
bimodal, with winter rains of longer duration and less intensity and 
summer rains of shorter duration and higher intensity. Periodic 
flooding appear to benefit spikedace in three ways: (1) Removing excess 
sediment from some portions of the stream; (2) removing nonnative fish 
species from a given area; and (3) increasing prey species diversity.
    Flooding in Aravaipa Creek has resulted in the transport of heavier 
loads of sediments such as cobble, gravel, and sand that deposited 
where the stream widens, gradient flattens, and velocity and turbulence 
decrease. Dams formed by such deposition can temporarily cause water to 
back up and break into braids downstream of the dam. The braided areas 
provide excellent nurseries for larval and juvenile fishes (Velasco 
1997).
    On the Gila River in New Mexico, flows fluctuate seasonally with 
snowmelt causing spring pulses and occasional floods, and late-summer 
or monsoonal rains producing floods of varying intensity and duration. 
These high flows benefit essential spikedace spawning and foraging 
habitat (Propst et al. 1986) as described above. Peak floods can modify 
channel morphology and sort and rearrange stream bed materials 
(Stefferud and Rinne 1996).
    Floods likely also benefit native fish by breaking up embedded 
bottom materials (Mueller 1984). A study of the Verde River analyzed 
the effects of flooding in 1993 and 1995, finding that these floods had 
notable effects on both native and nonnative fish species. Among other 
effects, the floods either stimulated spawning or enhanced recruitment 
of three of the native species, and may have eliminated one of the 
nonnative fish species (Rinne and Stefferud 1997).
    Flooding, as part of a natural hydrograph, temporarily removes 
nonnative fish species, which are not adapted to flooding. Thus 
flooding consequently removes the competitive pressures of nonnative 
fish species on native fish species which persist following the flood. 
A study on the differential responses of native and nonnative fishes in 
seven unregulated and three regulated streams or stream reaches that 
were sampled before and after major flooding noted that fish faunas of 
canyon-bound reaches of unregulated streams invariably shifted from a 
mixture of native and nonnative fish species to predominantly, and in 
some cases exclusively, native forms after large floods. Samples from 
regulated systems indicated relatively few or no changes in species 
composition due to releases from upstream dams at low, controlled 
volumes. However, during emergency releases, effects to nonnative fish 
species were similar to those seen with flooding on unregulated systems 
(Minckley and Meffe 1987).
    The onset of flooding also corresponds with an increased diversity 
of food items for spikedace. Reductions in the mainstream 
invertebrates, such as mayflies, cause the fish to expand its food base 
in an opportunistic manner. In addition, inflowing flood waters carry 
terrestrial invertebrates, such as ants, bees, and wasps 
(Hymenopterans), into

[[Page 75551]]

aquatic areas (Barber and Minckley 1983).
    Stream Gradient. Spikedace occupy streams with low to moderate 
gradients (Propst et al. 1986, Stefferud and Rinne 1996, Sublette et 
al. 1999). Specific gradient data are generally lacking, but the 
gradient of occupied portions of Aravaipa Creek varied between 
approximately 0.3 to < 1.0 percent (Barber et al. 1970, Rinne and 
Kroeger 1988, Rinne and Stefferud 1996). Smaller, younger spikedace are 
generally found in quiet water along pool margins over soft, fine-
grained bottoms (USFWS 1991a). Juveniles and larvae tend to occupy the 
margins of the stream adjacent to riffle habitats (Propst et al. 1986), 
and are also known to use backwater areas (Sublette et al. 1990).

Habitat Protected From Disturbance or Representative of the Historic 
Geographical and Ecological Distribution of a Species

    Nonnative fish species. One of the primary reasons for the decline 
of native species is the presence of nonnative fishes introduced 
accidentally or for sport, forage, or bait. Fish evolution in the arid 
American west is linked to disruptive geologic and climatic events 
which acted in concert over evolutionary time to decrease the 
availability and reliability of aquatic ecosystems. The fragmentation 
and reduction of aquatic ecosystems resulted in a fish fauna that was 
both diminished and restricted to the arid west. Lacking exposure to a 
wider range of species, western species seem to lack the competitive 
abilities and predator defenses developed by fishes from regions where 
more species are present (Douglas et al. 1994).
    The effects of nonnative fish competition on spikedace can be 
classified as either interference or exploitive. Interference 
competition occurs when individuals directly affect others, such as by 
fighting or preying upon them. Exploitive competition occurs when 
individuals affect others indirectly, such as through use of common 
resources (Douglas et al. 1994). Competition with regards to actual 
space is generally considered interference competition (Schoener 1983).
    The effects of nonnative fish preying on natives such as spikedace 
would be classified as interference competition. There is 
circumstantial evidence of the negative impacts of nonnative predators 
on native fishes for several stream reaches. Channel catfish, flathead 
catfish, and smallmouth bass all prey on native fishes, as evidenced by 
prey remains of native fishes in the stomachs of these predatory 
species (Propst et al. 1986). Smallmouth bass, rainbow trout, brown 
trout, and channel catfish became common in the Gila River above Turkey 
Creek and the three forks of the Gila River. In 1949, 52 spikedace were 
collected at Red Rock while channel catfish composed only 1.65 percent 
of the 607 fish collected. However, in 1977, only six spikedace were 
located at the same site, and the percentage of channel catfish had 
risen to 14.5 percent of 169 fish collected. The decline of spikedace 
and the increase of channel catfish is likely related (Anderson 1978).
    Similar interactions between native and nonnative fishes were 
observed for the upper reaches of the East Fork of the Gila River. In 
this system, native fish were limited, with spikedace being rare or 
absent, while nonnative channel catfish and smallmouth bass were 
moderately common prior to 1983 and 1984 floods. Post-1983 flooding, 
adult nonnative predators were generally absent and spikedace were 
collected in moderate numbers in 1985 (Propst et al. 1986).
    Interference competition occurs with species such as red shiner. 
Red shiner appear to be particularly detrimental to spikedace because 
although spikedace and shiners are separated geographically (i.e., 
allopatric), they occupy essentially the same habitat types. Where the 
two species are overlapping (i.e., sympatric), there is evidence of 
displacement of spikedace to less suitable habitats (USFWS 1991a). This 
means that if red shiners are present, suitable habitat for spikedace 
is reduced. Range expansion and species recovery may then be curtailed.
    One study focused on three stream reaches on the Gila River and 
Aravaipa Creek having only spikedace; one reach on the Verde River 
where spikedace and red shiner have co-occurred for three decades; and 
one reach on the Gila River where red shiner recently invaded areas and 
where spikedace had never been recorded. The study indicated that, for 
reaches where only spikedace were present, spikedace showed a 
preference for slower currents and smaller particles in the substrate 
than were generally available throughout the Gila River and Aravaipa 
Creek systems. For red shiner in the Verde River, the study showed that 
red shiner occupied waters that were generally slower and with smaller 
particle size in the substrate than were, on average, available in the 
system. The study concluded that, where the two species were caught 
together, habitats of spikedace were statistically indistinguishable 
from those occupied by red shiner. The study further concludes that 
spikedace, where co-occurring with red shiner, move into currents 
swifter than those selected when in isolation, while red shiner occupy 
the slower habitat, whether they are alone or with spikedace (Douglas 
et al. 1994).

Food

    Food Items. Spikedace are active, highly mobile fish that visually 
inspect drifting materials both at the surface and within the water 
column. Gustatory inspection, or taking potential prey items into the 
mouth before either swallowing or rejecting it, is also common (Barber 
and Minckley 1983). Prey body size is small, typically ranging from 
0.08 to 0.20 inches (2 to 5 mm) long (Anderson 1978).
    Stomach content analysis of spikedace determined that mayflies, 
caddisflies, true flies, stoneflies, and dragonflies are all prey items 
for spikedace. In one Gila River study, the frequency of occurrence was 
71 percent for mayflies, 34 percent for true flies, and 25 percent for 
caddisflies (Propst et al. 1986). A second Gila River study of five 
samples determined that the frequency of occurrence was 80 to 100 
percent for mayflies, 23.1 and 56.8 percent for true flies, and 48 to 
69.2 percent for caddisflies (Anderson 1978). At Aravaipa Creek, 
mayflies, caddisflies, true flies, stoneflies, and dragonflies were all 
prey items for spikedace, as were some winged insects and plant 
materials (Schreiber 1978).
    At Aravaipa Creek, spikedace consumed a total of 36 different prey 
items (Barber and Minckley 1983). Mayflies constituted the majority of 
prey items, followed by true flies. Of the mayflies consumed, 36.5 
percent were adults, while 33.3 percent were nymphs. Terrestrial 
invertebrates, including ants, wasps, and spiders, were also consumed, 
as were beetles, true bugs, caddisflies, and water fleas.
    Spikedace diet varies seasonally (Barber and Minckley 1983). 
Mayflies dominated stomach contents in July, but declined in August and 
September, increasing in importance again between October and June. 
When mayflies were available in lower numbers, spikedace consumed a 
greater variety of foods, including true bugs, true flies, beetles, and 
spiders.
    Spikedace diet varies with age class as well. Young spikedace, 
classified as < 0.9 in (22.9 mm) fed on a diversity of small-bodied 
invertebrates occurring in and on sediments along the margins of the 
creek. True flies were found most frequently, but water fleas and 
aerial adults of aquatic and terrestrial insects also provide 
significant parts of the diet. As juveniles grow and migrate into the

[[Page 75552]]

swifter currents of the channel, mayfly nymphs and adults increase in 
importance (Barber and Minckley 1983).
    Spikedace are very dependent on aquatic insects for sustenance, and 
production of the aquatic insects consumed by spikedace occurs mainly 
in riffle habitats (Propst et al. 1986). As a result, habitat selection 
influences food items found in stomach content analyses. Spikedace in 
pools had eaten the least diverse foods while those from riffles 
contained a greater variety of taxa, indicating that the presence of 
riffles is essential to the survival of spikedace as riffles in good 
condition and abundance help to ensure that a sufficient number and 
variety of prey items will continue to be available (Barber and 
Minckley 1983).
    Aquatic invertebrates that constitute the bulk of the spikedace 
diet have specific habitat parameters of their own. Mayflies, which 
constituted the largest percentage of prey items, spend their immature 
stages in fresh water. Mayfly nymphs occur in all types of fresh 
waters, wherever there is an abundance of oxygen, but they are most 
characteristic of shallow water. Mayflies found in spikedace stomach 
content analyses consisted of individuals from several genera, with 
individuals from the genus Baetidae constituting the highest percentage 
of prey from the mayfly order in the study by Schreiber (1978). 
Baetidae are free-ranging species of rapid waters that maintain 
themselves in currents by clinging to pebbles. Spikedace also consumed 
individuals from two other mayfly genera (Heptageniidae and 
Ephemerellidae), which are considered ``clinging species'' as they 
cling tightly to stones and other objects and may be found in greatest 
abundance in crevices and on the undersides of stones (Pennak 1978). 
The importance of gravel and cobble substrates is illustrated by the 
fact that these prey species, which make up the bulk of the spikedace 
diet, require these surfaces to persist.

Water Quality

    Pollutants. Water with low levels of pollutants is essential for 
the maintenance of spikedace. Spikedace occur in areas where mining, 
agriculture, livestock operations, and road construction and use are 
prevalent. Various pollutants are associated with these types of 
activities. For spikedace, waters should have low levels of pollutants 
such as copper, arsenic, mercury and cadmium; human and animal waste 
products; pesticides; suspended sediments; and gasoline or diesel fuels 
(D. Baker, USFWS, pers. comm. 2005). In addition, dissolved oxygen 
should be greater than 3 parts per million (ppm). If levels of 
dissolved oxygen are below 3 ppm, some stress may occur.
    Fish kills have been documented in the San Francisco River (Rathbun 
1969) and the San Pedro River (Eberhardt 1981), both of which are 
within the species' historical range. In both instances, leaching ponds 
associated with copper mines released waters into the streams, 
resulting in elevated levels of toxic chemicals. For the San Pedro 
River, this included elevated levels of iron, copper, manganese, and 
zinc. Both incidents resulted in die-offs of species inhabiting the 
streams. Eberhardt (1981) notes that no bottom-dwelling aquatic 
insects, live fish, or aquatic vegetation of any kind were found for a 
60 mi (97 km) stretch of river in the area affected by the spill. 
Rathbun (1969) reported similar results for the San Francisco River. 
The possibility for similar accidents, or pollution from other sources, 
exists throughout these species ranges due to their proximity to mines, 
communities, agricultural areas, and major transportation routes.
    Temperature. Temperatures of occupied spikedace habitat vary with 
time of year. In May, temperatures at Aravaipa Creek were uniformly 
66.2 [deg]F (19 [deg] C) (Barber et al. 1970). Summer temperatures 
remained at no more than 80.6 [deg]F (27 [deg]C) at Aravaipa Creek 
(Barber et al. 1970), and at a mean of 66.7 [deg]F (19.3 [deg]C) 
between June and November on the Gila River in the Forks area (at the 
Middle, West, and East Forks) and were at 69.4 [deg]F (20.8 [deg]C) in 
the Cliff-Gila Valley (Propst et al. 1986). Winter temperatures ranged 
between 69.1 [deg]F (20.6 [deg]C) in November down to 48.0 [deg]F (8.9 
[deg]C) in December at Aravaipa Creek (Barber and Minckley 1966). The 
overall range represented by these measures is between 35-85 [deg]F 
(1.7-29.4 [deg]C).

Reproduction and Rearing of Offspring

    As discussed above under flow velocities, spikedace use a variety 
of habitat types within the channel during their reproductive cycle and 
at various life stages. Although not typically associated with pools 
(Anderson 1978), pools are used by female spikedace during the breeding 
season while males remained in riffle habitats. Females leave the 
pools, generally on the downstream end of the riffle, and swim upstream 
to males in riffle habitat (Barber et al. 1970). Unlike loach minnow 
that deposit their eggs in a hole or depression, spikedace spawn in 
shallow riffles and broadcast their gametes (reproductive cells) into 
the water column. Spikedace eggs are adhesive and develop among the 
gravel and cobble of the riffles following spawning. Spawning in riffle 
habitat ensures that the eggs are well oxygenated and are not normally 
subject to suffocation by sediment deposition due to the swifter flows 
found in riffle habitats. However, after the eggs have adhered to the 
gravel and cobble substrate, excessive sedimentation could cause 
suffocation of the eggs (Propst et al. 1986 and Marsh 1991).

Primary Constituent Elements for the Spikedace

    Based on our current knowledge of the life history, biology, and 
ecology of the species and the requirements of the habitat to sustain 
the essential life history functions of the species, we have determined 
that the primary constituent elements essential to the conservation of 
the spikedace are:
    1. Permanent, flowing, water with low levels of pollutants, 
including:
    a. Living areas for adult spikedace with slow to swift flow 
velocities between 20 and 60 cm/second (8-24 inches/second) in shallow 
water between approximately 10 cm (4 inches) to one meter (40 inches) 
with shear zones where rapid flow borders slower flow, areas of sheet 
flow (or smoother, less turbulent flow) at the upper ends of mid-
channel sand/gravel bars, and eddies at downstream riffle edges;
    b. Living areas for juvenile spikedace with slow to moderate water 
velocities of approximately 18 cm/second (8 inches/second) or higher in 
shallow water between approximately 3 cm (1.2 inches) to one meter (40 
inches);
    c. Living areas for larval spikedace with slow to moderate flow 
velocities of approximately 10 cm/second (4 inches/second) or higher in 
shallow water approximately 3 cm (1.2 inches) to one meter (40 inches).
    d. Water with low levels of pollutants such as copper, arsenic, 
mercury and cadmium; human and animal waste products; pesticides; 
suspended sediments; and gasoline or diesel fuels and with dissolved 
oxygen levels greater than 3 parts per million (ppm).
    2. Sand, gravel, and cobble substrates with low or moderate amounts 
of fine sediment and substrate embeddedness. Suitable levels of 
embeddedness are generally maintained by a natural, unregulated 
hydrograph that allows for periodic flooding or, if flows are modified 
or regulated, a hydrograph that allows for adequate river functions, 
such as flows capable of transporting sediments.
    3. Streams that have:
    a. Low gradients of less than approximately 1.0 percent;

[[Page 75553]]

    b. Water temperatures in the approximate range of 35-85[deg] 
Fahrenheit (F) (1.7-29.4 [deg]C) (with natural diurnal and seasonal 
variation);
    c. Pool, riffle, run, and backwater components, and;
    d. An abundant aquatic insect food base consisting of mayflies, 
true flies, and caddisflies, stoneflies, and dragonflies.
    4. Habitat devoid of nonnative fish species detrimental to 
spikedace, or habitat in which detrimental nonnative fish are at levels 
which allow persistence of spikedace.
    5. Areas within perennial, interrupted stream courses which are 
periodically dewatered but that serve as connective corridors between 
occupied or seasonally occupied habitat and through which the species 
may move when the habitat is wetted.
    Each of the areas designated in this rule have been determined to 
contain sufficient PCEs to provide for one or more of the life history 
functions of the spikedace. In some cases, the PCEs exist as a result 
of ongoing Federal actions. As a result, ongoing Federal actions at the 
time of designation will be included in the baseline in any 
consultation conducted subsequent to this designation.

Loach Minnow

    The specific primary constituent elements essential to the 
conservation of the loach minnow are derived from the biological 
requirements of the loach minnow, as described below.

Space for Individual and Population Growth and Normal Behavior

    As noted for the spikedace above, streams in the Southwestern 
United States have a wide fluctuation in flows and resulting habitat 
conditions at different times of the year. Loach minnow persist in 
these varying conditions and, as discussed below, several studies have 
documented habitat conditions at occupied sites.

Habitat Preferences

    Flow Velocities. Loach minnow live on the bottom of small to large 
rivers, preferring shallow, swift, and turbulent riffles, living and 
feeding among clean, loose, gravel-to-cobble substrates (Anderson and 
Turner 1977, Barber and Minckley 1966, Britt 1982, Lee et al. 1980, 
Marsh et al. 2003, Minckley 1981, USFWS 1991b, Velasco 1997). Loach 
minnow are sometimes associated with filamentous (threadlike) algae 
(Anderson and Turner 1977, Lee et al. 1980, Minckley 1981). Specific 
habitat usage varies with the life stage of the fish, as well as 
geographically. As noted below, researchers have documented a range of 
flows in occupied areas.
    Flow rate studies have been completed on the Gila River, Tularosa 
River, San Francisco River, Aravaipa Creek, Deer Creek. Measured flows 
in habitat occupied by adult loach minnow ranged from 9.6 to 31.2 in/
second (24.4 to 79.2 cm/second) (Barber and Minckley 1966, Propst et 
al. 1988, Propst and Bestgen 1991, Rinne 1989). There is geographic 
variation in flow velocities used by adult loach minnow. Adult loach 
minnow in the Gila River preferred velocities of 1.2 to 14.4 in/second 
(3.0 to 36.6 cm/second), while those in Aravaipa Creek preferred 
velocities of 15.6 to 20.4 in/second (39.6 to 51.8 cm/second). This may 
be due to the fact that there was considerably more water at slower 
velocities available to loach minnow in the Gila River, and that there 
was more and larger cobble substrate in the Gila River, which creates 
more habitat of slower velocities for loach minnow use (Turner and 
Tafanelli 1983).
    Juvenile loach minnow generally occurred in areas where velocities 
were similar to those used by adults, but faster than those used by 
larvae. In the Gila, San Francisco, and Tularosa rivers, juveniles 
occupied areas with mean velocities ranging between 1.2-33.6 in/second 
(3.0 to 85.3 cm/second) (Propst et al. 1988, Propst and Bestgen 1991, 
Rinne 1989, Turner and Tafanelli 1983). Larval loach minnow move from 
spawning rocks to slower-velocity nursery areas after emergence, 
typically occupying areas with significantly slower velocities than 
juveniles and adults. Larval loach minnow in the Gila, San Francisco, 
and Tularosa rivers occupied areas that were shallower and 
significantly slower than areas where eggs were found (Propst et al. 
1988, Propst and Bestgen 1991). In the Gila, San Francisco, and 
Tularosa rivers, and Aravaipa Creek, larval loach minnow occupied areas 
with flow velocities ranging from 3.6 to 19.2 in/second (9.1 to 48.8 
cm/second).
    Loach minnow prefer shallow, swift, and turbulent riffles. The use 
of riffle habitat has been documented in Aravaipa Creek (Barber and 
Minckley 1966, Rinne 1989, Velasco 1997, Vives and Minckley 1990), 
Eagle Creek (Marsh et al. 2003), Tularosa River (Propst et al. 1984), 
and the Gila and San Francisco rivers (Britt 1982, Propst and Bestgen 
1991, Propst et al. 1984, Propst et al. 1988). Loach minnow also occur 
in stream segments that contain pool, riffle, and run habitats on the 
Blue, upper Gila, and San Francisco rivers (AGFD 1994, Bagley et al. 
1995, Montgomery 1985).
    The availability of pool and run habitats affects availability of 
prey species. While most of the food items of loach minnow are riffle 
species, two are not, including mayfly nymphs which, at times, made up 
17% of the total food volume of loach minnow in a study at Aravaipa 
Creek (Schreiber 1978). The presence of a variety of habitat types is 
therefore important to the persistence of loach minnow in a stream, 
even while they are typically associated with riffles.
    Substrates. Loach minnow in Aravaipa Creek occurred over a gravel-
pebble substrate with materials between 3 to 16 mm (0.12 to 0.63 in) 
and, except in the summer, were associated with the larger sizes of 
available substrate. The use of larger substrates was 
disproportionately greater than expected based on overall availability 
of substrate size in the stream, indicating that loach minnow have a 
preference for the larger substrate and tend to use areas with that 
substrate over areas with smaller substrate (Rinne 1989). For portions 
of the upper Gila River occupied by loach minnow in 1999 and 2000, 
substrates were characterized by gravel-pebble and cobble substrates, 
with 70 percent of the sites having a gravel-pebble substrate, and 14 
percent of the sites having cobble substrate (Rinne 2001).
    Loach minnow in Aravaipa Creek and the Gila River appeared to 
prefer cobble and gravel, avoiding areas dominated by sand or finer 
gravel. This may be due to the fact that loach minnow maintain a 
relatively stationary position on the bottom of a stream in flowing 
water. An irregular bottom, such as that created by cobble or larger 
gravels, creates pockets of lower water velocities around larger rocks 
where loach minnow can remain stationary with less energy expenditure 
(Turner and Tafanelli 1983). In the Gila and San Francisco rivers, the 
majority of loach minnow captured occurred in the upstream portion of a 
riffle rather than in the central and lower depositional sections of 
the riffle. This is likely due to the availability of interstitial 
spaces in the cobble-rubble substrate, which became filled with 
sediment more quickly in the central and lower sections of a riffle 
section as suspended sediment begins to drop out (Propst et al. 1984).
    Loach minnow use different substrates during different life stages. 
Embryos occurred primarily on large gravel to rubble, while larvae were 
found where substrate particles were smaller than that used by embryos. 
Juvenile fish occupy areas with substrates of larger particle size than 
larvae. Adults exhibited a narrower preference for substrates than did 
juveniles, and were most commonly

[[Page 75554]]

associated with gravel to cobble substrates (Propst and Bestgen 1991).
    As noted above, streams in the Southwestern United States have a 
wide fluctuation in flows and are periodically dewatered. While 
portions of stream segments included in this designation may experience 
dry periods, they are still considered essential because the loach 
minnow is adapted to this changing environment and will use these areas 
as connective corridors between occupied or seasonally occupied habitat 
when they are wetted.
    Flooding. Natural flows, including flooding, are part of an 
unregulated hydrograph and are important in maintaining loach minnow 
habitat. In areas where substantial diversions or impoundments have 
been constructed, loach minnow are less likely to occur. This is in 
part due to habitat changes caused by the construction, and in part due 
to the reduction of beneficial effects of flooding on loach minnow 
habitat. Flooding appears to positively affect loach minnow population 
dynamics by resulting in higher recruitment (reproduction and survival 
of young) and by decreasing the abundance of nonnative fishes.
    The construction of water diversions, by increasing water depth, 
has reduced or eliminated riffle habitat in many stream reaches. In 
addition, loach minnow are generally absent in stream reaches affected 
by impoundments. While the specific factor responsible for this is not 
known, it is likely related to modification of thermal regimes, 
habitat, food base, or discharge patterns. Flooding also cleans, 
rearranges, and rehabilitates important riffle habitat (Propst et al. 
1988).
    Flooding allows for the scouring of sand and gravel in riffle 
areas, which reduces the degree of embeddedness of cobble and boulder 
substrates (Britt 1982). Prior to flooding, excessive sediment in the 
bedload is typically deposited at the downstream undersurfaces of 
cobble and boulder substrate components where flow velocities are 
lowest, and can result in a higher degree of embeddedness (Rinne 2001). 
Following flooding, cavities created under cobbles by scouring action 
of the flood waters provides enhanced spawning habitat for loach 
minnow.
    Studies on the Gila, Tularosa, and San Francisco rivers, found that 
flooding is primarily a positive influence on native fish, and 
apparently had a positive influence on the relative abundance of loach 
minnow. Rather than following a typical pattern of winter mortality and 
population decline, high levels of recruitment occurred after the 
flood, and loach minnow relative abundance remained high through the 
next spring. Flooding has enhanced and enlarged loach minnow habitat, 
resulting in a greater survivorship of individuals through winter and 
spring (Propst et al. 1988). Similar results were observed on the Gila 
and San Francisco rivers following flooding in 1978 (Britt 1982).
    Natural flooding may also reduce the negative impacts of nonnative 
fish species on loach minnow. During significant floods, nonnative 
species were either displaced or destroyed, while native species were 
able to maintain their position in or adjacent to channel habitats, 
persist in micro refuges or recolonize should they be displaced (Britt 
1982, Minckley and Meffe 1987).
    Stream Gradient. In addition to the availability of riffle habitat, 
gradient may influence the distribution and abundance of loach minnow. 
In studies of the San Francisco River, Gila River, Aravaipa Creek, and 
the Blue River found loach minnow occurred in stream reaches where the 
gradient was generally shallow, ranging from 0.3 to 2.2 percent (Bagley 
et al. 1995, Rinne 1989, Rinne 2001).

Habitat Protected From Disturbance or Representative of the Historic 
Geographical and Ecological Distribution of a Species

    Nonnative fish species. As noted under the discussion of nonnative 
fish species in the spikedace primary constituent elements section 
above, nonnative fishes have been introduced for a variety of reasons, 
resulting in interference or exploitive competition. Interference 
competition, such as predation, may result from interactions between 
loach minnow and nonnative channel and flathead