Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List Northern Leatherside Chub as Endangered or Threatened, 63444-63478 [2011-25810]
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DEPARTMENT OF THE INTERIOR
Background
Fish and Wildlife Service
Section 4(b)(3)(B) of the Act (16
U.S.C. 1531 et seq.) requires that, for
any petition to revise the Federal Lists
of Endangered and Threatened Wildlife
and Plants that contains substantial
scientific or commercial information
that listing the species may be
warranted, we make a finding within 12
months of the date of receipt of the
petition. In this finding, we will
determine that the petitioned action is:
(1) Not warranted; (2) warranted; or (3)
warranted, but the immediate proposal
of a regulation implementing the
petitioned action is precluded by other
pending proposals to determine whether
species are endangered or threatened,
and expeditious progress is being made
to add or remove qualified species from
the Federal Lists of Endangered and
Threatened Wildlife and Plants. Section
4(b)(3)(C) of the Act requires that we
treat a petition for which the requested
action is found to be warranted but
precluded as though resubmitted on the
date of such finding, that is, requiring a
subsequent finding to be made within
12 months. We must publish these 12month findings in the Federal Register.
50 CFR Part 17
[Docket No. FWS–R6–ES–2011–0092; MO
92210–0–0008–B2]
Endangered and Threatened Wildlife
and Plants; 12-Month Finding on a
Petition To List Northern Leatherside
Chub as Endangered or Threatened
Fish and Wildlife Service,
Interior.
ACTION: Notice of 12-month petition
finding.
AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), announce a
12-month finding on a petition to list
the northern leatherside chub
(Lepidomeda copei) as endangered or
threatened and to designate critical
habitat under the Endangered Species
Act of 1973, as amended (Act). After
review of all available scientific and
commercial information, we find that
listing the northern leatherside chub
rangewide is not warranted at this time.
We ask the public to submit to us any
new information that becomes available
concerning the threats to the northern
leatherside chub or its habitat at any
time.
SUMMARY:
The finding announced in this
document was made on October 12,
2011.
DATES:
This finding is available on
the Internet at https://
www.regulations.gov at Docket Number
FWS–R6–ES–2011–0092. Supporting
documentation we used in preparing
this finding is available for public
inspection, by appointment, during
normal business hours at the U.S. Fish
and Wildlife Service, Utah Ecological
Services Field Office, 2369 West Orton
Circle, Suite 50, West Valley City, UT
84119. Please submit any new
information, materials, comments, or
questions concerning this finding to the
above street address.
FOR FURTHER INFORMATION CONTACT:
Larry Crist, Field Supervisor, Utah
Ecological Services Field Office (see
ADDRESSES); by telephone at 801–975–
3330; or by facsimile at 801–975–3331;
or Brian Kelly, Field Supervisor, Idaho
Ecological Services Field Office; by
telephone at 208–378–5243; or by
facsimile at 208–378–5262. If you use a
telecommunications device for the deaf
(TDD), please call the Federal
Information Relay Service (FIRS) at
800–877–8339.
SUPPLEMENTARY INFORMATION:
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ADDRESSES:
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Previous Federal Actions
On July 30, 2007, we received a
petition dated July 24, 2007, from Forest
Guardians (now WildEarth Guardians),
requesting that the Service: (1) Consider
all full species in our Mountain Prairie
Region ranked as G1 or G1G2 by the
organization NatureServe, except those
that are currently listed, proposed for
listing, or candidates for listing; and (2)
list each species as either endangered or
threatened. The petition included the
northern leatherside chub (Lepidomeda
copei), which is addressed in this
finding. The petition incorporated all
analysis, references, and documentation
provided by NatureServe in its online
database at https://www.natureserve.org/
into the petition. The document clearly
identified itself as a petition and
included the petitioners’ identification
information, as required in 50 CFR
424.14(a). We sent a letter to the
petitioners, dated August 24, 2007,
acknowledging receipt of the petition
and stating that, based on preliminary
review, we found no compelling
evidence to support an emergency
listing for any of the species covered by
the petition.
On March 19, 2008, WildEarth
Guardians filed a complaint (1:08–CV–
472–CKK) indicating that the Service
failed to comply with its mandatory
duty to make a preliminary 90-day
finding on their two multiple species
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petitions—one for mountain-prairie
species, and one for southwest species.
On February 5, 2009 (74 FR 6122), we
published a 90-day finding on 165
species from the petition to list 206
species in the mountain-prairie region
of the United States as endangered or
threatened under the Act. We found that
the petition did not present substantial
scientific or commercial information
indicating that listing was warranted for
these species and, therefore, did not
initiate further status reviews in
response to the petition. Two additional
species were reviewed in a January 6,
2009, 90-day finding (74 FR 419) and,
therefore, were not considered further in
the February 5, 2009, 90-day finding.
For the remaining 39 species, we
deferred our findings until a later date.
One species of the 39 remaining species,
Sphaeralcea gierischii (Gierisch
mallow), was already a candidate
species for listing; therefore, 38 species
remained. On March 13, 2009, the
Service and WildEarth Guardians filed a
stipulated settlement in the District of
Columbia Court, agreeing that the
Service would submit to the Federal
Register a 90-day finding on the
remaining 38 mountain-prairie species
by August 9, 2009.
On August 18, 2009, we published a
notice of 90-day finding (74 FR 41649)
on 38 species from the petition to list
206 species in the mountain-prairie
region of the United States as
endangered or threatened under the Act.
Of the 38 species, we found that the
petition presented substantial scientific
and commercial information for 29
species indicating that a listing may be
warranted. The northern leatherside
chub addressed in this 12-month
finding was included in the list of 29
species. We initiated a status review of
the 29 species to determine if listing
was warranted. We also opened a 60day public comment period to allow all
interested parties an opportunity to
provide information on the status of the
29 species. The public comment period
closed on October 19, 2009. We received
224 public comments. Of these, five
specifically mentioned northern
leatherside chub. All substantial
information we received was carefully
considered in this finding. This notice
constitutes the 12-month finding on the
July 24, 2007, petition to list the
northern leatherside chub as
endangered or threatened.
Species Information
The northern leatherside chub
(Lepidomeda copei) is a rare desert fish
in the minnow family (Cyprinidae) that
occurs in northern Utah and Nevada,
southern and eastern Idaho, and western
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Wyoming (Johnson et al. 2004, pp. 842–
843; Utah Division of Wildlife
Resources (UDWR) 2009, pp. 28–30;
McAbee 2011, entire). The species is
native to smaller, mid-elevation, desert
streams in the northeastern portions of
the Great Basin region (draining to the
Great Salt Lake) and the southern and
eastern portions of the Pacific
Northwest Region (draining to the
Pacific Ocean) (Johnson et al. 2004, pp.
842–843; UDWR 2009, pp. 28–30). Like
many western North American nongame fish species, little was known
about its biology, ecology, or status until
recently (Belk and Johnson 2007, pp.
67–68).
Taxonomy and Species Description
The northern leatherside chub is one
of two species, along with the southern
leatherside chub (Lepidomeda aliciae),
recently re-classified from the single
species ‘leatherside chub’
(Snyderichthys copei or Gila copei)
(Johnson et al. 2004, pp. 841, 852).
Throughout the remainder of this
finding, references to leatherside chub
indicate data collected before the two
species were delineated, and references
to southern leatherside chub and
northern leatherside chub indicate data
specific to each species, exclusively.
Because the northern and southern
species were only recently separated,
most species descriptions and lifehistory investigations are a combination
of the two species. While many
characteristics are common to both
species, we will describe characteristics
of only the northern leatherside chub
when possible.
The taxonomic history of leatherside
chub is complex. Even when considered
a single species, taxonomists classified
the leatherside chub in at least seven
different genera over the past century
and a half (Johnson et al. 2004, p. 841).
The type locality for leatherside chub
(Squalius copei; Jordan and Gilbert
1881) is from the Bear River at
Evanston, Wyoming (UDWR 2009, p.
24). Classification by Miller in the midtwentieth century (1945) placed
leatherside chub in the monotypic
genus Snyderichthys, but shortly
thereafter Uyeno (1960) assigned it to
the genus Gila (the chubs), subgenus
Snyderichthys (UDWR 2009, p. 25).
Many fisheries texts accepted Gila copei
as the taxonomic classification over the
next 40 years (Sigler and Miller 1963, p.
74; Sigler and Sigler 1996, p. 77), but
acceptance was not unanimous, as
evidenced by the American Fisheries
Society supporting Snyderichthys copei
in 2004 (UDWR 2009, p. 25). Taxonomic
discrepancy was not fully rectified until
a short time ago. Recent research
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demonstrated that what was previously
considered the ‘leatherside chub’ is in
fact two distinct species with discrete
geographic, ecological, morphological,
and genetic characteristics (Johnson et
al. 2004, pp. 841, 852). Moreover,
neither species belongs in the
previously accepted genera, but rather
both belong in the genus Lepidomeda, a
group commonly referred to as the
spinedaces (Johnson et al. 2004, pp.
841, 852).
Three different species concepts
validate this taxonomic revision.
Genetic analysis endorses two
evolutionarily separate species under
the phylogenetic species concept
(defines a species as a set of organisms
with a unique genetic history) (Johnson
and Jordan 2000, pp. 1029, 1033;
Johnson et al. 2004, pp. 841, 851). In
addition, morphologic (cranial shape)
and ecological (feeding and growth
rates) divergence support two distinct
species under the similarity and
ecological species models, respectively
(Johnson et al. 2004, p. 851). It also is
worth noting that current taxonomy
aligns with discrete geographic
distributions of the species, with the
unoccupied Weber River separating the
two species’ ranges and the
uninhabitable Great Salt Lake
preventing natural interaction between
individuals of the two species (Belk and
Johnson 2007, p. 69). Supported by
multiple lines of evidence indicating
that southern (Lepidomeda aliciae) and
northern (L. copei) leatherside chub are
two distinct species, the American
Fisheries Society now recognizes the
two species as such (Jelks et al. 2008, p.
390). Because northern leatherside chub
is an acknowledged species, it is a
listable entity under the Act.
The northern leatherside chub is a
small fish, less than 150 millimeters
(mm) (6 inches (in.)) in length, that
received its common name from the
leathery appearance created by small
scales on a trim, tapering body (Sigler
and Sigler 1996, p. 78; UDWR 2009, p.
26). It has rounded dorsal and anal fins,
each with eight fin rays (Sigler and
Sigler 1996, p. 78). Typically, the
northern leatherside chub is bluish
above and silver below, but orange to
red coloration may occur on some fins
(Sigler and Sigler 1996, p. 78). Males
also have a golden-red speck at the
upper end of the gill opening and
between the eyes and the upper jaw
(Sigler and Sigler 1996, p. 78).
Two characteristics that distinguish
northern and southern leatherside chubs
from each other are cranial shape and
size-at-age (UDWR 2009, p. 26).
Northern leatherside chub have deeper
heads with shorter snouts (Johnson et al.
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2004, p. 850) and are typically 15
percent smaller than southern
leatherside chub of the same age, with
northern leatherside chub reaching total
length of approximately 60 mm (2.4 in.)
at age 2 and 71 mm (2.8 in.) at age 3
(Belk et al. 2005, pp. 177, 181).
Life History
Before 1995, the life history of the
leatherside chub was not well known,
with just a few observations of age,
growth, or reproduction (Johnson et al.
1995, p. 183). Investigations of
populations now known as southern
leatherside chub demonstrated the
species could live up to 8 years and
reached sexual maturity at age 2
(Johnson et al. 1995, p. 185). Further
work corroborated that the majority of
northern leatherside chub also mature at
age 2, but some not until age 4 (Belk et
al. 2005, p. 181).
The bulk of our reproductive
knowledge about this species comes
from the hatchery setting, where
successful propagation has occurred.
Northern leatherside chub produce
translucent, whitish fertilized eggs that
are adhesive and can clump together or
adhere to substrate (Billman et al.
2008a, p. 277). In natural populations,
eggs typically hatch in late June (Belk et
al. 2005, p. 181), but in hatchery
conditions, spawning occurs between
April and September (Billman et al.
2008a, p. 276). In controlled hatchery
conditions, eggs hatch between 4 and 6
days to produce fry that still reside in
the substrate (Billman et al. 2008a, p.
277). Six days after hatching, fry emerge
from the substrate, and by 40 days after
hatching most have tripled in length to
approximately 16 mm (0.63 in.)
(Billman et al. 2008a, p. 277).
In the hatchery setting, spawning
overwhelmingly occurs over cobble
substrate (which provides interstitial
space for eggs) and in higher velocity
flows (which provide oxygen and
remove fine sediment) (Billman et al.
2008a, p. 277). These conditions
indicate main channel riffle or run
habitats are likely the natural location of
northern leatherside chub spawning.
Northern and southern leatherside
chub have similar, relatively broad
diets, with aquatic and terrestrial insects
and crustaceans accounting for 75
percent of their consumption in one
study (Bell and Belk 2004, p. 414).
Aquatic and terrestrial insects
dominated the autumnal northern
leatherside chub diet at the Sulphur
Creek sample site (Bell and Belk 2004,
p. 414). The species foraged on a wide
variety of prey items common to both
the substrate and stream drift (Bell and
Belk 2004, p. 414). However, it is likely
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that the species’ diet varies throughout
the year and at different locations based
on available food (Bell and Belk 2004,
p. 414). The study results indicate that
the species’ diet overlaps with other
native and nonnative fish, including
sculpins (Cottidae family), shiners
(Cyprinids), and cutthroat
(Oncorhynchus clarkii) and brown
(Salmo trutta) trout, suggesting possible
competitive interactions (Bell and Belk
2004, p. 414).
Habitat
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Northern leatherside chub inhabit
small desert streams between elevations
of approximately 1,250 to 2,750 meters
(m) (4,100 to 9,000 feet (ft)) in the Bear,
Snake, and Green River subregions (as
defined by the U.S. Geological Survey’s
(USGS) National Hydrography Dataset
(NHD)) (Idaho Department of Fish and
Game (IDFG) 2005, p. 1). Streams of this
nature encounter extreme seasonal and
annual physical conditions because of
variation in temperature and
precipitation (Wilson and Belk 2001, p.
40). Therefore, northern leatherside
chub must endure cold winters and hot
summers (water temperature from 0 to
25 °C (32 to 77 °F); high, turbid spring
runoff and low, clear summer base
flows; and periodic droughts that reduce
water in streams (Wilson and Belk 2001,
p. 40). It is likely that enduring these
variable extreme habitat conditions
adapted northern leatherside chub to
tolerate varied habitat conditions.
Most habitat descriptions are the
result of investigations before
leatherside chub was divided into two
species, but habitat descriptions for the
northern leatherside chub can be
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evaluated based on their distinct
geographic range. Summer water
temperature of occupied habitat is
reportedly 10 to 23 °C (50 to 73.4 °F),
but the current belief is that northern
leatherside chub’s range is actually
restricted to 15.5 to 20 °C (59.9 to 68 °F)
(UDWR 2009, p. 27). The species does
not persist in lakes or reservoirs (UDWR
2009, p. 27). Northern leatherside chub
prefer low water velocities (15 to 23
centimeters per second (cm/s) (0.5 to
0.75 feet per second (fps)), and their
probability of occurrence decreases at
higher velocities (UDWR 2009, p. 40).
Water velocity and temperature
generally limit the northern leatherside
chub from occupying high headwater
streams. Recent habitat investigations
show that northern leatherside chub
habitat associations are consistent with
the results for the southern species (Belk
and Wesner 2010, p. 12), allowing us to
consider habitat data for southern
leatherside chub as generally acceptable
for northern leatherside chub.
Distribution
Recent and ongoing investigations
continue to revise the current and
historical distributions of northern
leatherside chub by verifying or
invalidating historical specimens,
intensely resampling specific stream
reaches suspected to harbor the species,
and documenting new northern
leatherside chub occurrences. For this
finding, we completed a white paper
summarizing current and historical
distributions through fall 2010 (McAbee
2011, entire). We analyzed current and
historical range at the subbasin level
(otherwise known as 8-digit Hydrologic
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Unit Code (HUC) in the USGS’ NHD or
HUC8), and current population
locations at the subwatershed level
(otherwise known as 12-digit HUC or
HUC12). We identified population
locations in one to multiple
subwatersheds, depending on the
perceived interaction between
individuals. State wildlife agencies and
universities reviewed the document to
ensure that it summarized their data
collection correctly. Information from
our population summary (also known as
‘white paper’) is used throughout this
finding to inform our conclusions
(McAbee 2011, entire).
The documented historical range of
northern leatherside chub includes
portions of the Bear River subregion that
drain to the Great Salt Lake, and
discontinuous subbasins in the Upper
Snake River subregion that eventually
drain to the Pacific Ocean (Figure 1;
Table 1). It is unclear how this species
came to inhabit two presently
unconnected hydrologic regions. Past
geologic events associated with the
draining of Lake Bonneville or the
connection of the Bear River to the
Snake River as recently as 30,000 years
ago (Behnke 1992, p. 134) are likely
responsible for the separation (UDWR
2009, p. 25). The range of northern
leatherside chub has declined over the
past 50 years (Wilson and Belk 2001, p.
36; Johnson et al. 2004, pp. 841–842;
UDWR 2009, p. 24), and the verified
current range of the species is now
limited to five of the eight documented
historical subbasins (Table 1). However,
additional survey efforts are planned or
ongoing.
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TABLE 1—DOCUMENTED RANGE OF THE NORTHERN LEATHERSIDE CHUB BY SUBBASIN
NATIONAL HYDROGRAPHY DATASET LOCATIONS
Status
Subregion (code)
Subbasin code and name
Bear River (1601) ...............................................................
Upper Green River (1404) ..................................................
In addition to the historical range, two
populations are now known from the
Upper Green River subregion in the
Colorado River region (Table 1). It is
possible that these occurrences are the
result of human introductions.
However, genetic analysis is necessary
to confirm the origin of these
populations, and this information is not
yet available. For the purposes of this
finding, we acknowledge these
populations’ conservation value.
Because verifiable, historical records
are sparse, we are unable to produce a
large-scale historical range boundary
with this information. Therefore, we
Upper Bear River ........................................
Central Bear River
Logan River ................................................
Lower Bear River
Snake Headwaters .....................................
Salt River
Goose Creek
Little Wood River ........................................
Upper Green—Slate Creek ........................
14040107
Upper Snake River (1704) ..................................................
16010101
16010102
16010203
16010204
17040101
17040105
17040211
17040221
14040103
Currently occupied.
Blacks Fork
Historical records only.
Currently occupied.
Historical records only.
Currently occupied but
unconfirmed native
range.
previously accepted collections were
refuted, leading to a clearer
understanding of the species’ range
(Northern Leatherside Chub
Conservation Team 2010, p. 4). In fact,
many subbasins once identified as part
of the species’ current or historical
range are now either questioned or
invalidated (Table 2). While we expect
that the northern leatherside chub’s
natural distribution is more continuous
than verifiable historical and current
data indicate, we have no specific data
to describe this range other than what is
presented in this finding (Figure 1;
Table 3).
rely on the known, verified collections
to analyze the status of the species.
Northern leatherside chub are
difficult to identify in the field because
they can be confused with other species
with similar appearances. Therefore,
many collections were incorrectly
classified as northern leatherside chub,
when in fact they were later verified as
Utah chub (Gila atraria), speckled dace
(Rhinichthys osculus), or redside shiner
(Richardsonius balteatus).
Ichthyologists at Brigham Young and
Idaho State Universities worked to
verify historical records and validate
recent collections in order to
authenticate data. As a result, many
TABLE 2—SUSPECTED SUBBASINS THAT ARE NO LONGER CONSIDERED NORTHERN LEATHERSIDE CHUB CURRENT OR
HISTORICAL RANGE
NATIONAL HYDROGRAPHY DATASET LOCATIONS
Status
Subregion (code)
Subregion code and name
Upper Snake River (1704) ...............................
Salmon Falls Creek .......................
17040219
Big Wood River .............................
unknown
Bruneau & Snake Rivers ...............
17050104
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Raft River ......................................
17040213
Great Salt Lake (1602) ....................................
Blackfoot River ..............................
17040210
Middle Snake (1705) ........................................
17040207
Upper Owyhee ..............................
16020309
Curlew Valley ................................
Historical specimen incorrectly classified; No
verified records.
Unvouchered historical record not corroborated by recent sampling; No verified
records.
Unvouchered recent record not corroborated
by repeated sampling; No verified records.
Unvouchered recent record not corroborated
by repeated sampling; No verified records.
Historical specimens incorrectly classified; No
verified records.
Museum records need to be checked.
Listed in conservation agreement, but no supporting data; No records.
TABLE 3—EXTANT POPULATIONS OF NORTHERN LEATHERSIDE CHUB IN 2010
NATIONAL HYDROGRAPHY DATASET LOCATIONS
POPULATION NAME
Subregion
Bear River .............................
Upper Bear ..................................................
STATE
Upper Mill/Deadman Creeks ..............................................
Upper Sulphur/La Chapelle Creeks ....................................
UT/WY
WY
Subbasin
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TABLE 3—EXTANT POPULATIONS OF NORTHERN LEATHERSIDE CHUB IN 2010—Continued
NATIONAL HYDROGRAPHY DATASET LOCATIONS
POPULATION NAME
STATE
Yellow Creek .......................................................................
Upper Twin Creek ...............................................................
Rock Creek .........................................................................
UT/WY
WY
WY
Central Bear ................................................
Dry Fork Smiths Fork .........................................................
Muddy Creek ......................................................................
WY
WY
Snake Headwaters ......................................
Salt River .....................................................
Pacific Creek .......................................................................
Jackknife Creek ..................................................................
WY
ID
Goose Creek ...............................................
Trapper Creek .....................................................................
Beaverdam Creek ...............................................................
Trout Creek .........................................................................
ID
ID
NV/ID
Upper Green River/Slate Creek ..................
Blacks Fork ..................................................
North Fork Slate Creek .......................................................
Upper Hams Fork ...............................................................
WY
WY
Subregion
Snake River ..........................
Green River ..........................
Subbasin
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Overall, our identification and
confirmation of a northern leatherside
population for this finding required the
presence of multiple age classes,
collection of a dense number of fish
(more than five individuals), and
documentation of fish collections over
multiple years. Meeting these criteria
demonstrated to us that northern
leatherside chub populations were
resident, reproducing, and persisting
over time. Within the current range of
the northern leatherside chub, we thus
delineated 14 extant populations,
spread across the Bear (7), Snake (5),
and Green (2) River subregions (Table
3). Locations where northern leatherside
chub were collected, but were not
classified as a population, are detailed
in our white paper analysis (McAbee
2011, entire).
Bear River Subregion
The Bear River subregion harbors
seven extant populations of northern
leatherside chub across two subbasins:
Five in the Upper Bear River subbasin
and two in the Central Bear River
subbasin (Table 3). We are aware of the
presence of some individual fish
upstream (Hayden and Stillwater Forks)
(Nadolski and Thompson 2004, pp. 3, 4,
7; Chase 2010, pers. comm.) and
downstream (mainstem Bear River and
lower Sulphur Creek) (Wyoming Game
and Fish Department (WGFD) 2008, pp.
1, 3; Belk and Wesner 2010, p. 5) of
these areas; however, we do not
consider these as populations because
they do not meet the definition of a
population outlined above (specifically
presence of multiple age classes and
collection of a dense number of fish)
due to their low densities and lack of
juvenile fish.
In the Upper Bear River subbasin, the
Upper Mill/Deadman Creeks and
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Yellow Creek populations harbor dense,
reproducing populations of northern
leatherside chub (McKay and Thompson
2010, pp. 4–7). In the Upper Mill/
Deadman Creeks population,
approximately 1,000 individuals per
kilometer are found in Deadman Creek
(McKay and Thompson 2010, pp. 6–7)
and groups occur downstream in Mill
Creek in Utah and Wyoming (Nadolski
and Thompson 2004, pp. 3, 7; Belk and
Wesner 2010, p. 5). The Yellow Creek
population has groups of individuals
from the upper reaches in Utah
downstream through Wyoming and in
Thief Creek, a tributary (Thompson et
al. 2008, pp. 8–9; Zafft et al. 2009, p. 3;
Belk and Wesner 2010, p. 5). The Upper
Sulphur/La Chapelle Creeks population
above Sulphur Creek Reservoir also
harbors abundant northern leatherside
chubs (Zafft et al. 2009, p. 3). This
population is likely isolated by the
presence of Sulphur Creek Reservoir,
which is unsuitable habitat and is
stocked with predatory nonnative trout
(brown trout before 2000, rainbow trout
(Oncorhynchus mykiss) currently)
(WGFD 2010, pp. 3–6).
Twin Creek, a large tributary to the
Bear River in the Upper Bear River
subbasin, contains two populations of
northern leatherside chub: Rock Creek
and Upper Twin Creek. Multiple
tributaries to Twin Creek comprise the
Upper Twin Creek population,
including Clear Creek and the North,
East, and South Forks of Twin Creek
(Belk and Wesner 2010, p. 5; Colyer and
Dahle 2010, p. 5). These populations
can presumably interact but are likely
isolated from all other populations
because sampling has failed to detect
downstream emigrants (McKay and
Thompson 2010, p. 18).
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In the Central Bear River subbasin, the
Smiths Fork area harbors at least two
large populations: Dry Fork Smiths Fork
and Muddy Creek. Both contain
hundreds of individuals (Colyer and
Dahle 2007, p. 8; Belk and Wesner 2010,
p. 5). Individual fish from this
population can disperse downstream,
but many perish in irrigation canals
before reaching the mainstem Bear River
(Roberts and Rahel 2008, pp. 951, 955).
Snake River Subregion
The Snake River subregion contains
eight subbasins with historical northern
leatherside chub observations (UDWR
2009, pp. 44, 48). However, biologists
have reexamined museum records,
resampled stream reaches with
presumed past observations, and refined
the identification key for the species. As
a result, four of the eight subbasins, the
Raft, Big Wood, and Blackfoot Rivers,
and Salmon Falls Creek, with past
records were downgraded to ‘‘unlikely
to have contained or to contain northern
leatherside chub’’ (Table 2). One
subbasin has verified historical records
but no current records (Little Wood
River), and is thus considered extirpated
unless new information is obtained.
The remaining three subbasins with
verified current records are Goose
Creek, Snake Headwaters, and Salt River
(Table 1; McAbee 2011, p. 2). Within the
Goose Creek subbasin, we know of three
reproducing populations at Trapper,
Beaverdam, and Trout Creeks. All three
populations have persisted over the past
10 to 15 years (Grunder et al. 1987, p.
80; Wilson and Belk 1996, p. 17; Keeley
2010, pp. 3–29). Trapper Creek is
isolated from the other two by Oakley
Reservoir, but there are no barriers
between Trout and Beaverdam Creeks,
and the populations likely interact.
Collections of single northern
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leatherside chub individuals in
mainstem Goose Creek (Keeley 2010,
pp. 24–29) indicate individuals may be
dispersing from these two populations.
Recent collections of individuals in Pole
Creek in the Goose Creek subbasin
suggest a population may occur in this
tributary as well (Grunder 2010, p. 3).
However, no juvenile fish were
collected, and this is the first year
northern leatherside were documented
in this reach (Keeley 2010, pp. 6–11).
Although these collections may
constitute a colonization event, we do
not consider Pole Creek a population in
this finding because multiple age classes
were not present (demonstrating the
area has not shown successful
reproduction or recruitment).
The single population in the Snake
Headwaters subbasin is Pacific Creek,
which has persisted since its discovery
in the 1950s (Grand Teton National Park
2009, pp. 1–2; Zafft et al. 2009, pp. 2–
5). In the Salt River subbasin, a single
population is found in Jackknife Creek
and its tributaries (Isaak and Hubert
2001, pp. 26–27; Keeley 2010, pp. 45–
60). The Pacific Creek population is
separated from the Jackknife Creek
population by large stream distances
and large reservoirs, making individual
dispersal between the two populations
unlikely. In addition, both the Pacific
Creek and Jackknife Creek populations
are isolated from the Goose Creek
subbasin by upwards of 350 streamkilometers (km) and many large
reservoirs.
Green River Subregion
There are two northern leatherside
chub populations in the Green River
subregion, one each in the Upper Green
River/Slate Creek and Blacks Fork
subbasins (Table 3). However, based on
the lack of historical collections in the
Green River subregion, the lack of a
documented natural connection
between the Green River subregion and
the Bear or Snake River subregions, and
the prevalence of human translocations
of fish, we determine that it is unlikely
that this is the species’ native range. The
first population was identified in 1988
in North Fork Slate Creek (WGFD 1988
in Zafft et al. 2009, p. 2), and
represented the first population outside
the Bear or Snake River subregions. This
population is approximately 30 km (18
mi) east of the Bear and Snake River
subregions, making it close enough to be
the result of a human introduction. The
Upper Hams Fork population was later
identified (Wheeler 1997 in Zafft et al.
2009, p. 3), and is located
approximately 35 km (22 mi) northeast
of the North Fork Slate Creek
population. In addition, this population
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is just across the subregion boundary
with the Dry Fork Smiths Fork
population, making it even more
possible that the population is the result
of a human introduction. We also are
aware of individual fish in the nearby
West Fork of the Hams Fork in 2006
(Zafft et al. 2009, p. 3), which we
include as part of the Upper Hams Fork
population because they can interact.
These two populations indicate that
northern leatherside chub are persisting
in the Green River subregion. Whether
these populations are native, or are
recent human introductions, has yet to
be resolved. Genetic analysis to answer
this question is planned for completion
in the near future, and will hopefully
resolve this question. Until proof can be
presented that these populations are not
native, their conservation value to the
species must be considered.
It is worth noting that genetic analysis
of southern leatherside chub collections
in the Fremont River (Green River
subregion) demonstrated that they were
not native, but rather a genetic match to
an East Fork Sevier River population
(Barrager and Johnson 2010, p. 7). These
results show that a successful human
translocation of a surrogate species has
occurred, and is possible for the
northern leatherside chub.
In summary, 14 extant northern
leatherside chub populations persist
across 3 subregions: 7 populations in
the Bear River subregion; 5 populations
in the Snake River subregion; and 2
populations in the Green River
subregion (Figure 1, Table 1). Land
ownership is comprised of privately
owned land (31.5 percent in the States
of Idaho, Nevada, Utah, and Wyoming),
as well as lands managed by BLM (30
percent), NPS (3.5 percent), USFS (30.5
percent), and the States of Wyoming (4.3
percent) and Idaho (0.04 percent)
(Service 2011, pp. 11–17). We will
investigate threats to these extant
populations in the remainder of this
finding.
Summary of Information Pertaining to
the Five Factors
Section 4 of the Act (16 U.S.C. 1533)
and implementing regulations (50 CFR
part 424) set forth procedures for adding
species to, removing species from, or
reclassifying species on the Federal
Lists of Endangered and Threatened
Wildlife and Plants. Under section
4(a)(1) of the Act, a species may be
determined to be endangered or
threatened based on any of the
following five factors:
(A) The present or threatened
destruction, modification, or
curtailment of its habitat or range;
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(B) Overutilization for commercial,
recreational, scientific, or educational
purposes;
(C) Disease or predation;
(D) The inadequacy of existing
regulatory mechanisms; or
(E) Other natural or manmade factors
affecting its continued existence.
In making our 12-month finding on
the petition we considered and
evaluated the best available scientific
and commercial information.
Information pertaining to the northern
leatherside chub in relation to the five
factors provided in section 4(a)(1) of the
Act is discussed below.
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
The following potential threats that
may affect the habitat or range of
northern leatherside chub are discussed
in this section, including: (1) Livestock
grazing; (2) oil and gas development; (3)
mining; (4) water development; (5)
water quality; and (6) fragmentation and
isolation of existing populations.
Livestock Grazing
Livestock presence generally disturbs
streamside and instream habitats,
particularly in the arid west where
riparian and stream habitats are fragile
ecosystems (Kauffman and Krueger
1984, p. 431; Helfman 2007, p. 102).
Livestock grazing is especially
detrimental to riparian habitats because
livestock spend disproportionately more
time near water (Helfman 2007, p. 102).
They typically eat and trample riparian
vegetation and compact soil, which
leads to impacts that include increased
sediment inputs from runoff, nutrient
loading from livestock waste, higher
stream temperatures from lack of
vegetation shading, and reduction in
invertebrate abundance (Kauffman and
Krueger 1984, p. 432; Wohl and Carline
1996, p. 264; Stoddard et al. 2005, p. 8).
These impacts combine to degrade
habitats for many fish species,
especially species requiring cool, clear
water and gravel substrate, such as
salmonids (Helfman 2007, p. 34).
However, some species, such as the
northern leatherside chub, can tolerate
certain habitat changes and persist
despite disturbed conditions. Increased
sediment may alter a fish community
and allow for domination by species
that thrive or contend well with sandy
substrates (Sutherland et al. 2002, pp.
1801–1802) (see Water Quality section
for specific discussion of sedimentation
and northern leatherside chub).
Similarly, increased water temperature
also may alter the distribution of
species, forcing out cold-water species,
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and allowing for warm-water species to
enter a habitat (Field et al. 2007, p. 631).
Northern leatherside chub apparently
can tolerate certain disturbances, largely
because they can survive extreme
environmental conditions to which they
are evolutionarily adapted (Belk and
Johnson 2007, p. 70), such as high water
temperatures (Isaak and Hubert 2001, p.
27; Wilson and Belk 2001, p. 39), with
a critical thermal maximum of
approximately 30 °C (86 °F) (Billman et
al. 2008b, p. 463) and persist in large
numbers in areas deemed degraded
(Muddy Creek and Upper Twin Creek).
However, we do not have specific data
indicating their tolerances to all water
quality conditions. While habitats
impacted by grazing may not be
preferred, populations of northern
leatherside chub persist in locations
deemed degraded and impaired.
For example, in the Bear River
subregion, the Upper Twin Creek
population persists even though
overgrazing has reduced the riparian
vegetation cover (Colyer and Dahle
2010, pp. 16, 19) to the point that the
streams are classified as degraded (BLM
2011, entire). In the same subregion,
Muddy Creek is another example of a
dense northern leatherside chub
population that persists (Colyer and
Dahle 2007, Table 6) despite altered
conditions from overgrazing that result
in a very wide, shallow channel and
degraded riparian habitats (BLM 1999,
p. 7; BLM 2007a, pp. 1–2; Prichard
1998, p. 8; BLM 2005, p. 5). In the Snake
River subregion, populations persist in
Beaverdam and Trapper Creeks
although the water quality in both
streams is impaired, most likely as the
result of overgrazing (Lay 2003, pp. 69–
70, 125). However, it is worth noting
that impacts from grazing affect
Beaverdam and Trapper Creeks in
qualitatively different ways (high
suspended sediment) than Muddy and
Upper Twin Creeks (reduced riparian
cover).
Data indicate that some level of
livestock grazing occurs across the
entire range of the northern leatherside
chub and near all existing populations
(Service 2011, pp. 18–24). Because of
the prevalence of grazing across the
western United States, the species will
likely encounter livestock grazing
effects. However, we expect effects from
livestock grazing will decrease over time
on Federally managed lands as
management agencies address livestock
grazing practices. For example, the U.S.
Forest Service (USFS) recently
implemented changes in the grazing
management on the Goose Creek grazing
allotment that occurs in the upstream
portions of Beaverdam and Trout Creeks
(Northern Leatherside Chub
Conservation Team 2011, p. 3). On a
broader scale, Bureau of Land
Management (BLM) guidelines in Idaho
(BLM 1997, p. 4, Standard #2),
Wyoming (BLM 2007c, p. 1, Standard
#2), Utah (BLM 2009, p. 1, Standard
#1b), and Nevada (BLM 2007b, p. 1,
Standard #2) require all streams to have
riparian health consistent with natural,
functional habitats, indicating that
grazing impacts will be improving on
BLM lands. Upstream land ownership
for all but three occupied subwatersheds (11 of 14) is over 50 percent
federally owned, demonstrating the
importance of Federal land management
for northern leatherside chub (see
detailed discussion of land ownership
under Factor D below).
In summary, there is no apparent
indication that grazed areas are
negatively impacting existing
populations of northern leatherside,
although grazing has likely affected
water quality (discussed later).
Populations of northern leatherside
chub occur in a wide variety of habitat
conditions, from unaltered locations to
those with heavily altered riparian
conditions impacted by livestock
grazing practices. In fact, some of the
densest populations occur in areas that
are heavily grazed. Also, there is
evidence to indicate that livestock
grazing impacts will be declining in the
future, as more sustainable rangeland
management practices are applied. We
found no information that grazing may
act on this species to the point that the
63451
species itself may be at risk, nor is it
likely to become so.
Oil and Gas Development
Oil and gas exploration and
development can impact fish habitats,
primarily through degraded watershed
health. Increased land disturbance from
roads and pads reduce water quality
because of increased sediment loads
(WGFD 2004, p. 25; Matherne 2006, p.
1). Road culverts also can fragment fish
habitats if they are designed in a way
that impedes fish migration (Aedo et al.
2009, p. 2). Drilling operations often
require water depletions from local
water sources and can result in
accidental spills of contaminants into
fish habitat (Stalfort 1998, p. ES–2;
Etkin 2009, pp. 35–42). Accumulations
of contaminants, such as hydrocarbons
and produced water (water locked away
in formation with oil and gas that is
typically not suitable for human or
wildlife use), can result in lethal or
sublethal impacts across the entire
aquatic food chain, including sensitive
fish species (Stalfort 1998, Section 4).
Water depletions can reduce or
eliminate aquatic habitat, creating
multiple negative effects (see Water
Development, below).
To analyze the potential impacts from
oil and gas development, we
investigated past and present levels of
development and the potential for
future development in occupied
populations. We summarized the
analysis in an internal white paper
(Hotze 2011, pp. 1–8) and reference the
results throughout this finding. Data
sources for the investigation included
Bureau of Land Management Resource
Management Plans (BLM 1985, entire;
BLM 2010, entire); State databases of oil
and gas development (Hess et al. 2008,
entire; Utah Division of Oil, Gas, and
Mining 2009, entire; Wyoming Oil and
Gas Conservation Commission 2009,
entire; State of Idaho 2011, entire); and
energy development maps (Garside and
Hess 2007, map; Energy Information
Administration (EIA) 2009a, map; EIA
2009b, map; EIA 2011, entire).
TABLE 4—SUMMARY OF OIL AND GAS DEVELOPMENT IN EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS
Population name
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National hydrography dataset locations
Subregion
Upper Bear ..............................
Active oil & gas
wells (inactive)
Overlap with
known coalbed
methane reserves (%)
Upper Mill/Deadman Creeks ...
UT/
WY
WY
0 (6)
4
2 (1)
47
28 (63)
25
0 (0)
9
Subbasin
Bear River ................................
State
Upper Sulphur/La Chapelle
Creeks.
Yellow Creek ...........................
Upper Twin Creek ....................
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UT/
WY
WY
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TABLE 4—SUMMARY OF OIL AND GAS DEVELOPMENT IN EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS—
Continued
National hydrography dataset locations
Population name
Subregion
Snake Headwaters ..................
Salt River .................................
Goose Creek ...........................
Green River ..............................
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Snake River .............................
Upper Green River/Slate Creek
Blacks Fork ..............................
We found that throughout the range of
northern leatherside chub, neither
active development nor potential for
future development of oil and gas are
common, with both being limited to one
localized area, the Yellow Creek
population in the Bear River subregion
(Table 4) (Hotze 2011, pp. 1–8). A
quarter of the Yellow Creek population
overlaps with proven Federal oil and
gas reserves, mostly in the western and
northern portions of the subwatershed
(EIA 2009a, map; Hotze 2011, p. 5).
Current and past well activity follow
this overlap, with 63 inactive and 28
active wells in the population’s
subwatershed, mainly near the occupied
areas of Thief Creek and lower Yellow
Creek in Wyoming (Hotze 2011, p. 2).
No development activity has occurred
in the upstream portions of Yellow
Creek, which contain high densities of
northern leatherside chub, and no
proven Federal oil and gas reserves
occur there. A quarter of the Yellow
Creek population overlaps with coalbed
methane reserves, in the eastern-central
portion in Wyoming, suggesting the
potential for development (Hotze 2011,
p. 7).
The populations in the northern
portions of the Bear River subregion
have seen little past or current
development and have a low probability
of future development. The Twin Fork
drainage has only one inactive well
across the Rock and Upper Twin Creek
populations (Hotze 2011, p. 2). A small
portion (less than 1 percent) of the Rock
Creek population overlaps with the
Collett Creek field, which contains
proven Federal oil and gas reserves
(Hotze 2011, pp. 4–5). The Smiths Fork
drainage is north of the Wyoming
Thrust Belt (an optimal geologic
formation for retrieving oil and gas
resources), so development of oil
reserves has not historically occurred in
the Muddy Creek and Dry Fork Smiths
Fork populations, and is not likely to
19:12 Oct 11, 2011
Rock Creek ..............................
Dry Fork Smiths Fork ..............
Muddy Creek ...........................
Pacific Creek ...........................
Jackknife Creek .......................
Trapper Creek .........................
Beaverdam Creek ....................
Trout Creek ..............................
North Fork Slate Creek ...........
Upper Hams Fork ....................
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occur in the future (Hotze 2011, p. 2).
Similarly, there is very little overlap
between these two populations and
known coalbed reserves (less than 1
percent of the Dry Fork Smiths Fork
population) (Hotze 2011, p. 7), making
it unlikely that coalbed methane
development will take place in these
populations.
In the remainder of the Bear River
subregion, past and current resource
development is rare, but resource
potential exists. The Upper Sulphur/La
Chapelle Creeks population has only
one inactive and two active wells, but
half of the population area overlaps
with coalbed methane reserves (Hotze
2011, pp. 2, 7). However, the area has
a low potential for resource extraction
demonstrated by the low presence of
current or past wells and the distance to
the closest producing well. The Upper
Mill/Deadman Creeks population has
only six inactive wells, all in the Utah
portion of the population’s
subwatershed (Hotze 2011, p. 2). Less
than 5 percent of the Upper Mill/
Deadman Creeks population overlaps
with coalbed methane reserves, all in
the most downstream reaches that do
not contain northern leatherside chub
(Hotze 2011, p. 7).
The Snake River subregion
populations occur in areas that do not
have active development and are
characterized as low potential for future
development (Hotze 2011, pp. 1–2).
Currently, all populations in the Goose
Creek subbasin (Trout, Trapper, and
Beaverdam Creeks) are in areas open for
oil and gas leasing, but there are no
producing wells in either the Idaho or
Nevada portions (Hotze 2011, p. 2).
Further east, there is potential for
development of the Idaho-Wyoming
Thrust Belt in the Jackknife Creek
population, but the probability of
discovering and developing oil in this
area is considered low by BLM (BLM
2010, p. Q–1). No wells are currently
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Active oil & gas
wells (inactive)
WY
WY
WY
WY
ID
ID
ID
NV/ID
WY
WY
Subbasin
Central Bear ............................
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0
0
0
0
0
0
0
0
0
0
(1)
(0)
(0)
(0)
(0)
(0)
(0)
(0)
(5)
(0)
Overlap with
known coalbed
methane reserves (%)
131
0.1
0
0
16.6
0
0
0
32
0
found in the Jackknife Creek population
(Hotze 2011, p. 2). Finally, the Pacific
Creek population may overlap with the
Jackson Hole coalbed methane field, but
management by Grand Teton National
Park makes it unlikely that development
of these resources will take place (Hotze
2011, p. 2).
In the portions of the Green River
subregion occupied by northern
leatherside chub, there is little active or
historical development of any kind and
minor potential for future development
exists, chiefly from coalbed methane
reserves. The Upper Hams Fork is
outside of any known coalbed reserves,
the population is north of the Wyoming
Thrust Belt and west of the Wyoming
Overthrust coalbed reserves (Hotze
2011, pp. 2, 7). As a result, it has no
active or inactive wells within its
boundary, and we consider future
development potential in this
population negligible (Hotze 2011, p. 2).
The North Fork Slate Creek population
has only five inactive wells within its
boundary, but overlaps with the
Wyoming Overthrust coalbed reserves
in the upstream third of the population
(Hotze 2011, pp. 2, 7). It is possible that
development could occur in this
population, but we have no data to
indicate that development is planned or
imminent. Also, without environmental
planning for this development, we
cannot say what impacts the
development would have on northern
leatherside chub.
To summarize, past, present, and
future oil and gas development is likely
to impact one population of northern
leatherside chub, Yellow Creek in the
Bear River subregion, and only in the
downstream half. Only two populations
overlay with proven Federal oil and gas
reserves, Yellow and Rock Creeks (Table
4). The Rock Creek overlap is
insignificant, accounting for less than
1 percent of the population’s
subwatershed. However, the Yellow
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Creek overlap is sizable, at
approximately a quarter of the
population’s subwatershed.
Correspondingly, only Yellow Creek has
measurable levels of current energy
development at a moderate scale.
Because the impacts to Yellow Creek are
downstream of a large portion of the
occupied area within the population
boundary, we find oil and gas
development does not threaten the
persistence of the Yellow Creek
population. Although some resource
potential is found throughout the range
of the species, future development is
unlikely to occur or impact all but one
population (Yellow Creek). Oil and gas
development impacts only a small
portion of the species’ total range, and
the impacted population will likely
persist in upstream reaches. We found
no information that oil and gas
development may act on this species to
the point that the species itself may be
at risk, nor is it likely to become so.
Mining
Hardrock mining for such materials as
gold, copper, iron ore, uranium, and
others is the most common mining
activity in the western United States
(Trout Unlimited 2011, p. 1).
Underground and surface mining
activities have the potential to
negatively affect fish species by
releasing solid wastes and contaminated
mine water (Helfman 2007, pp. 160–
161; Trout Unlimited 2011, p. 1).
Solid waste from mining includes
overburden, which is the topsoil and
surface rock that is above a mineral
deposit; waste rock, which is the low
grade ore that surrounds a mineral
deposit; and tailings, which are the finegrained materials that are left over from
the processing of raw ore (Trout
Unlimited 2011, p. 1). Abandoned and
currently operating mine sites can
impact downstream fish species from
the sedimentation that results from
erosion of waste rock (Helfman 2007,
pp. 112, 113) (see Water Quality section
for specific discussion of sedmentation
and northern leatherside chub).
Contaminated mine water is the
ground or surface water that
accumulates and is discharged from a
mine or its associated waste rock piles
(Trout Unlimited 2011, p. 1). This water
can cause deleterious effects to fishes
via acidification and heavy metal
contamination (Helfman 2007, pp. 160–
161, 168–169). Stream acidification
results from drainage of waters from
mines or their waste rock by-products.
This water is highly toxic because the
associated low pH harms fish
respiratory function and can impact
reproduction rates and rearing outcomes
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(Helfman 2007, p. 159). Low pH in
aquatic systems also can negatively
affect aquatic plants and
macroinvertebrates and thereby reduce
food sources and habitat for fish
(Helfman 2007, pp. 160–161; Trout
Unlimited 2011, p. 1). Heavy metal
contamination of aquatic habitats also
can result from mine water that is
discharged from mines or that infiltrates
and then runs out of waste rock or
tailings piles. Heavy metals such as
lead, copper, zinc, cadmium, mercury,
aluminum, iron, manganese, and
selenium can be toxic to fishes at low
concentrations and can ultimately
interfere with embryonic development,
digestion, respiration, general growth,
and survival (Helfman 2007, pp. 160,
161; Trout Unlimited 2011, p. 1).
We assessed mining activity within
the range of northern leatherside chub
by reviewing mining location data as
reported by State agencies and in
GeoCommunicator, the publication Web
site for the National Integrated Land
System as operated by a joint venture
between the BLM and USFS (https://
www.Geocommunicator.gov/GeoComm,
Mining Claims). This information shows
that uranium, coal, and non-coal (all
other mine types) were prospected for in
much of the northern leatherside chub
range (Service 2011, pp. 25–32).
However, the majority of these mines or
prospects are historical and are no
longer in operation (Service 2011, pp.
25–32).
In the Bear River subregion, there are
no abandoned mines, active mines, or
mining claims in the Upper Mill/
Deadman Creeks, Upper Sulphur/La
Chapelle Creeks, Yellow Creek, or
Muddy Creek populations (Service
2011, pp. 28, 30). In the Rock Creek
drainage, there are 11 quarter sections
with 1 to 5 mining claims each;
however, these are located downstream
of northern leatherside chub occupied
habitat and are not being actively
developed (Service 2011, p. 29). The
Upper Twin Creek population has one
abandoned mine about 2 miles (mi)
upstream of occupied habitat on North
Fork Twin Creek, and approximately
four abandoned mines upstream of
occupied habitat on East Fork Twin
Creek (Service 2011, p. 29). Also, a
small portion of the headwaters of the
Upper Twin Creek population is under
an active coal lease; however, the active
mining associated with this lease is
found on the other side of the watershed
boundary, meaning impacts will not
affect northern leatherside chub (WSGS
2009, map). We have no information to
indicate that any of these abandoned
mines are having an effect on adjacent
northern leatherside chub in the Upper
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Twin Creek population. In the Dry Fork
Smiths Fork population, there are eight
quarter sections with one to five mining
claims; however, these are located
primarily downstream of northern
leatherside chub occupied habitat, are
not developed, and thus should not
have an effect on occupied habitat
(Service 2011, p. 30).
In the Snake River subregion, there
are no abandoned mines, active mines,
or mining claims within northern
leatherside chub habitats in the Trout or
Jackknife Creek populations (Service
2011, pp. 25, 26). The Trapper Creek
and Beaverdam Creek populations have
several abandoned mines of lignite and
uranium prospects/deposits that are
adjacent to northern leatherside chub
occupied habitat (about four to five sites
in each drainage) (Service 2011, p. 25).
Because prospects and identified
deposits usually involve a small
disturbance such as a shallow hole or a
short adit (an entrance to an
underground mine which is horizontal
or nearly horizontal), we determine
these features are having negligible
impact on northern leatherside chub
occupied habitat. In the Pacific Creek
population where northern leatherside
chub are found, there are 11 quarter
sections with 1 to 5 mining claims each
(Service 2011, p. 27). These mining
claims occur upstream of northern
leatherside chub occupied habitat; these
claims are not developed, and we have
no information to suggest that these will
be developed. At this time we have no
information to suggest that any of these
abandoned mines or mining claims are
having a significant effect on adjacent
northern leatherside chub at an
individual or population level.
In the Green River subregion, neither
the Slate Creek nor the Upper Hams
Fork populations have abandoned
mines, active mines, or mining claims
(Service 2011, pp. 31–32). Thus, there
are no effects from mining on northern
leatherside chub populations in these
areas.
In summary, recent examination of
mining activity in northern leatherside
chub habitat has determined that
mining-related impacts are limited.
Mining was historically prevalent in
occupied portions of the Bear and Snake
subregions, but largely absent in
occupied portions of the Green River
subregion. Some mines do still operate
in northern leatherside chub
populations. However, we have no
information at this time to suggest that
mining activities are having an effect on
water resources or habitat of northern
leatherside chub. We found no
information that mining activities may
act on this species to the point that the
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species itself may be at risk, nor is it
likely to become so.
Water Development
Water development in western North
America has the potential to impact
native fish species by degrading aquatic
habitats and altering natural ecological
mechanisms (Minckley and Douglas
1991, p. 15; Naiman et al. 2002, p. 455).
Water development can affect aquatic
species through desiccation (drying that
results in loss of habitat), reduction in
available habitat from reduced flows,
reduced population connectivity, and
decreases in water quality (e.g., higher
water temperatures in summer months
because of lower water volume or
increased concentration of pollutants).
In addition, water diversion structures
often entrain (pull in and trap) fish into
canal systems along with irrigation
water, placing fish in lethal habitats
because water supplies are typically
shut off at the end of the irrigation
season (Roberts and Rahel 2008, p. 951).
The development of water resources
in the Bear, Snake, and Green River
subregions has led to the conversion of
some northern leatherside chub stream
habitats into seasonally dewatered
channels (complete absence of flowing
water) (Nadolski and Thompson 2004,
p. 4; Thompson et al. 2008, p. 20;
McKay et al. 2009, p. iv; Yarbrough
2011, pers. comm.), representing a
complete loss of habitat in some areas.
In the following analysis, we consider
the impact of complete dewatering and
entrainment on each northern
leatherside chub population. We do not
consider impacts of reduced water
volume for each population because
leatherside chub have a broad tolerance
of extreme environmental conditions
(Belk and Johnson 2007, p. 70) and have
persisted in a number of locations
where low water levels occurred.
Leatherside chub are adapted to
periodic low water conditions and can
survive in remnant pools for several
weeks after the water flow is completely
eliminated (Belk and Johnson 2007, p.
70). Therefore, complete dewatering
represents the highest risk for mortality
of individuals and represents the
primary barrier for movement.
Similarly, entrainment creates the risk
of direct mortality, as entrained fish,
especially northern leatherside chub,
are not expected to survive in irrigation
canals.
Dewatering of Streams
We determined occurrences and
temporal extent of recent dewatering
events in occupied populations through
agency reports and expert accounts. In
recent, recorded history, no known
dewatering events occurred near 8 of the
14 populations: Upper Mill/Deadman
Creeks (Thompson 2011, pers. comm.);
Dry Fork Smiths Fork (BLM 2002, p. B–
7); Muddy Creek (Henderson 2011, pers.
comm.); Pacific Creek (Clark et al. 2004,
pp. 26–29; O’Ney 2011, pers. comm.);
Jackknife Creek (Lyman 2011, pers.
comm.); Trapper Creek (Bisson 2011,
pers. comm.); Trout Creek (Lay 2003, p.
8); and Upper Hams Fork (Yarbrough
2011, pers. comm.). As a result, we
determine that these populations are not
threatened by current water
development.
However, six northern leatherside
populations did experience complete
dewatering events in areas adjacent to or
within their known habitat and we
further analyzed effects to these
populations (Table 5). All dewatering
events are seasonal in nature and occur
in mid to late summer (Nadolski and
Thompson 2004, p. 4; Thompson et al.
2008, p. 20; McKay et al. 2009, pp. 20–
21), when dry weather and irrigation
pressures are highest. We will address
dewatering conditions and the
population response for five population
areas (two populations, Rock and Upper
Twin Creek, are experiencing the same
nearby dewatering, so will be
considered together): (1) Upper
Sulphur/La Chapelle Creeks; (2) Yellow
Creek; (3) Rock and Upper Twin Creeks,
all in the Bear River subregion; (4)
Beaverdam Creek in the Snake River
subregion; and (5) North Fork Slate
Creek in the Green River subregion.
TABLE 5—NORTHERN LEATHERSIDE CHUB POPULATIONS THAT HAVE ENCOUNTERED PAST DEWATERING EVENTS AND THE
NATURE OF THESE EVENTS
National hydrography dataset locations
Population
Subregion
Bear River ............................
Upper Bear ........................
Nature of dewatering event
Upper Sulphur/La Chapelle
Creeks.
Yellow Creek .....................
Dewatering upstream in headwaters & downstream
near reservoir; No threat to population.
In downstream portion; Reproduction still occurs locally & upstream portions unaffected; No threat to
population.
Downstream of both populations; Does not prevent
movement between populations; No threat to populations.
In downstream portion; Population sustains in perennial portion but becomes isolated; No threat to population.
Downstream portions are intermittent but local areas
perennial; No threat to population.
Subbasin
Upper Twin Creek .............
Rock Creek
Goose Creek .....................
Beaverdam Creek .............
Green River .........................
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Snake River .........................
Slate Creek ........................
North Fork Slate Creek .....
Irrigation demands periodically
dewater portions of Upper Sulphur
Creek directly upstream of Sulphur
Reservoir (Amadio 2011, pers. comm.),
possibly preventing the migration of
northern leatherside chub between the
two occupied areas of the Upper
Sulphur/La Chapelle Creeks population
in the Bear River subregion.
Additionally, headwater portions of this
area were dewatered in Utah in 2007
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(Webber 2008, p. 21). However, neither
of the dewatered areas are the primary
occupied portion of the population, as
northern leatherside chub occupy
portions of Sulphur and La Chapelle
Creek in Wyoming upstream of Sulphur
Creek Reservoir, and also downstream
of the Utah border. Because dewatering
events do not impact habitats occupied
by the population, we conclude
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dewatering is not a threat to this
population.
The lower reaches of Yellow Creek
(Bear River subregion) have low flows
(Thompson et al. 2008, p. 21) or are
completely dewatered (Nadolski and
Thompson 2004, p. 4) in the summer
months. However, successful
reproduction was evident in nearby
upstream portions of Yellow Creek in
2002, 2005, and 2008 (Thompson et al.
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2008, p. 11). Upper portions of Yellow
Creek (from Utah-Wyoming border to
the headwaters) retain water throughout
the year and are occupied by a healthy
northern leatherside chub community
(Thompson et al. 2008, p. 21). The
upper portions of Yellow Creek likely
act as a source population to lower
Yellow Creek reaches in years of
extreme low water, and for this reason
dewatering is not a threat to this
population.
Lower portions of mainstem Twin
Creek in the Bear River subregion are
completely dewatered by an irrigation
diversion 6.75 km (4.2 mi) upstream of
the Utah-Wyoming border during most
of the irrigation season (Thompson et al.
2008, p. 20). However, northern
leatherside chub are present in several
locations upstream of this diversion,
including two extant populations—the
Rock and Upper Twin Creek
populations (Belk and Wesner 2010, p.
5; Colyer and Dahle 2010, p. 5).
Northern leatherside chub move
through the lower mainstem Twin Creek
(downstream of the diversion) to the
mainstem Bear River during portions of
the year when there is water (Thompson
et al. 2008, p. 20), demonstrating the
connectivity of these rivers. Because of
the connection between upstream and
downstream communities within this
population, and because the upstream
communities of Rock and Clear Creeks
are perennial streams (Wyoming
Department of Environmental Quality
2010, p. 15), dewatering is not a threat
to these populations.
Beaverdam Creek in the Snake River
subregion begins at the confluence of
Left Hand Fork Beaverdam Creek and
Right Hand Fork Beaverdam Creek, with
flow being supported by approximately
seven intermittent or ephemeral streams
(Lay 2003, p. 99). Lower portions of
Beaverdam Creek are commonly
dewatered, leading the Idaho
Department of Environmental Quality
(IDEQ) to identify the lower two-thirds
of Beaverdam Creek as intermittent (Lay
2003, p. 99). These sections include
portions near the Emery Ranch and the
lowest 3 to 5 km (1.9 to 3.1 mi) of
stream from Emery Ranch to Goose
Creek (Lay 2003, p. 99). However, Upper
Beaverdam Creek maintains high
enough year-round flow to sustain a
cutthroat trout population (Lay 2003, p.
99). Northern leatherside chub
populations also are located in the
perennial waters of upper Beaverdam
Creek. The effect of ephemeral
dewatering in lower Beaverdam Creek
on northern leatherside chub is to
seasonally isolate this population from
other Goose Creek populations in all but
the wettest conditions. Because this
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population is reproducing and selfsustaining, we conclude that seasonal
dewatering is not currently a threat to
the population.
Portions of Slate Creek in the Green
River subregion and its tributaries are
intermittent (Yarbrough 2011, pers.
comm.). The South and Middle Forks of
Slate Creek were completely dewatered
in July 2003 (WGFD 2009, p. 4). We
have little information regarding the
demography of this population, except
that several age classes were found in
mainstem Slate Creek and North Fork of
Slate Creek during 2003 (WGFD 2009, p.
5). This suggests reproduction and
juvenile recruitment is not impacted by
dewatering in adjacent streams. There is
no record of dewatering in the North
Fork or mainstem of Slate Creek where
northern leatherside chub are found.
Because dewatering occurs downstream
of occupied habitat and reproduction is
occurring, we do not consider
dewatering a threat to this population.
While the preceding analysis
considered past and current water
development, future water development
across the range of northern leatherside
chub may alter the level of impacts.
Northern leatherside chub-occupied
subwatersheds in Utah and Idaho are
closed to new water appropriations for
any significant consumptive use such as
large-scale irrigation (Dean 2011, pers.
comm.; Jordan 2011, pers. comm.). In
contrast, subwatersheds occupied by
northern leatherside chub in Nevada
and Wyoming are still open to new
water appropriations (Randall 2011,
pers. comm.; Jacobs and Brosz 2000, p.
7). However, we expect minimal future
water development near the only
population in Nevada (Trout Creek)
because of the low human population
density in the area and because we are
not aware of any new water-intensive
land use planned for the area (Randall
2011, pers. comm.). Although irrigated
agriculture production is the largest
water use in Wyoming’s three northern
leatherside chub occupied subbasins
(Schroeder and Hinckley 2007, p. 5–2),
agricultural water use is expected to
increase at most 9.2, 5.6, and 5.2 percent
for the Green, Bear, and Snake
subregions in Wyoming, respectively,
between 2007 and 2037 (Schroeder and
Hinckley 2007, pp. 6–2—6–4). We
consider these small increases and
conclude that this full development
would not be a threat to northern
leatherside chub in Wyoming. Because
predictions for future water
development for occupied subbasins
indicate water development is either
prohibited or minimal, the available
information indicates that the northern
leatherside chub is not threatened
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throughout all of its range by water
development, nor is it likely to become
so.
In summary, while northern
leatherside chub are adapted to endure
short-term low water conditions,
complete dewatering events can result
in the temporary, seasonal loss of
northern leatherside chub habitat.
However, in all of the dewatering events
described above, individual fish are
either not locally impacted by
dewatering or are able to move to nearby
perennial reaches during the dewatered
period. Additionally, future water
development is closed in Utah and
Idaho, unlikely in Nevada, and smallscale in Wyoming. We found no
information that dewatering may act on
this species to the point that the species
itself may be at risk, nor is it likely to
become so.
Entrainment
Fish encountering unscreened
irrigation intake structures are often
injured or killed, primarily through
entrainment, the process by which
aquatic organisms are diverted into
irrigation structures (Zydlewski and
Johnson 2002, p. 1276; Gale et al. 2008,
p. 1541). Entrainment into irrigation
canals is considered a major source of
mortality for fish populations in the
western United States because
individual fish entering canal systems
typically cannot escape back into stream
habitat (Carlson and Rahel 2007, p.
1335; Roberts and Rahel 2008, p. 951).
Near 100 percent mortality is expected
once an individual enters an irrigation
canal structure because of the numerous
unnatural conditions in the canals.
Individuals entrained into canals are
exposed to higher water temperatures
and non-natural substrate (often
concrete), while also becoming easier
prey for predatory birds and mammals.
Those fish that survive for long periods
ultimately encounter the end of the
irrigation season, when water is often
shut off from the canals (Roberts and
Rahel 2008, p. 954), trapping individual
fish in dewatered, lethal conditions.
Screening intake structures is the most
common method to minimize
entrainment of fish (Zydlewski and
Johnson 2002, p. 1276; Moyle and Israel
2005, p. 20; Gale et al. 2008, p. 1541).
However, screening facilities must be
designed to meet individual criteria at
each location, taking into account the
sizes and swimming abilities of the fish
species that will encounter the
structure.
Because they are small minnows with
weak swimming abilities, all northern
leatherside chub entrained into canals
are expected to die (Roberts and Rahel
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2008, p. 957). For example, irrigation
facilities in the Smiths Fork River
entrained an estimated 195 northern
leatherside chub downstream of two
populations, Dry Fork Smiths Fork and
Muddy Creek (Roberts and Rahel 2008,
p. 957). Similarly, a large irrigation
structure in lower mainstem Twin Creek
entrained native fish species, including
northern leatherside chub, downstream
of two populations, Upper Twin and
Rock Creeks (Colyer and Dahle 2010, p.
5). These data show that where northern
leatherside encounter irrigation
structures, they are entrained.
Across the range of northern
leatherside chub, irrigation is a common
practice. However, besides the large
network of irrigation intakes in the
Smiths Fork (Carlson and Rahel 2007, p.
1336) and Twin Creek drainages (Colyer
and Dahle 2010, p. 6), we know of no
other documented instances of
entrainment. In addition, many of the
diversions that could entrain northern
leatherside chub in the Twin Creek
drainage were updated with screened,
fish-friendly structures by Trout
Unlimited over the past few years
(Colyer and Dahle 2010, p. 6), thereby
greatly reducing their threat to northern
leatherside chub.
Based on the data from the Smiths
Fork and Twin Creek drainages, we
conclude entrainment into canals is
likely preferentially targeting migrating
individuals because entrainment is
occurring primarily downstream of
populations. This makes entrainment
more of an agent of fragmentation than
a threat to extant populations. We
expect that when irrigation diversions
are not taking the entire water supply
from the stream, an unknown portion of
individuals can bypass the structure,
likely providing enough population
interaction (as shown in other species:
Hanson 2001, p. 331; Gale et al. 2008,
p. 1546). For example, because the
documented entrainment in the Smiths
Fork drainage is downstream of both
populations, individuals from the Dry
Fork Smiths Fork population could
reach the Muddy Creek population
without encountering the entraining
structure.
In summary, while the potential
impact of entrainment occurs across the
species’ range (anywhere an unscreened
diversion exists), it has been
documented downstream of only four
populations, all in the Bear River
subregion. While the loss of emigrating
individuals is important to adequate
species metapopulation dynamics,
entrainment likely affects only a small
fraction of migrating individuals and
does not impact resident individuals in
the core population areas. Entrainment
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may reduce the ability of northern
leatherside chub to migrate between
populations, but without an irrigation
structure diverting the entire stream,
some individuals should be able to
bypass structures. We found no
information that entrainment may act on
this species to the point that the species
itself may be at risk, nor is it likely to
become so.
Summary of Water Development
We determined that current levels of
water development—entrainment and
dewatering—impact only a small
portion of the extant populations of
northern leatherside chub, and
primarily occur downstream of the
inhabited population areas. Because
these factors are not occurring near the
existing core areas, they are largely
impacting migrating individuals and
reducing population connectivity, not
imperiling overall population
persistence. Future water development
is closed in Utah and Idaho, unlikely in
Nevada, and small-scale in Wyoming.
We found no information that water
development may act on this species to
the point that the species itself may be
at risk, nor is it likely to become so.
Water Quality
Water pollution and habitat
degradation impair the ability of aquatic
systems to support life for at least 34
percent of the river and stream habitats
in the United States (Environmental
Protection Agency (EPA) 2002, p. 12).
Examples of pollutants of concern for
aquatic systems include heavy metals,
biocides, endocrine disrupters, acid
rain, sediments, dissolved solids, and
excess nutrients (Stoddard et al. 2005,
p. 8; Helfman 2007, p. 158). The effects
of pollution on fish can include
immediate death or long-term
disabilities, such as increased incidence
of disease, abnormalities, and altered
behavioral or metabolic responses
(Helfman 2007, p. 160).
Waters that do not meet water-quality
standards due to point and non-point
sources of pollution are listed on the
EPA’s 303(d) list of impaired water
bodies. Therefore, we used the EPA
303(d) list of impaired waters (see
discussion under Factor D) to assist in
determining if pollution or degraded
water quality is a threat to northern
leatherside chub (EPA 2010, pp. 1–2).
Because the EPA’s water quality
standards are thought to be protective of
aquatic life, we determined that a
stream not listed as impaired on the
EPA 303(d) list did not have a high
enough magnitude of pollution impacts
to warrant further analysis. States must
submit to the EPA a 303(d) list (water-
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quality-limited waters) and a 305(b)
report (status of the State’s waters) every
2 years, making our analysis up-to-date.
Of the 14 northern leatherside
populations, 2 populations that occur in
the Goose Creek subbasin (Trapper and
Beaverdam Creeks) are found in streams
listed in Idaho’s most recent 2008
integrated 303(d)/305(b) report. Trapper
Creek’s water quality is listed as
impaired from nutrients (defined by
Idaho as including phosphorus,
nitrogen, and organic compounds),
specifically total phosphorous,
sediment, and dissolved oxygen (IDEQ
2010, p. vii). Beaverdam Creek is
impaired by nutrients (total
phosphorous), bacteria, temperature,
sediment, and dissolved oxygen (Lay
2003, p. xxii). Impaired water-quality
conditions in both creeks may be the
result of livestock grazing effects (Lay
2003, pp. 69–70, 125).
These impairments can have varying
impacts to fish and stream habitats,
although we have no information on
how these impacted water-quality
parameters potentially affect northern
leatherside chub. Phosphorus is
typically in limited supply in aquatic
systems and, therefore, excess
phosphorus is considered a nutrient
pollutant. Excess phosphorus can cause
eutrophication, which often results in
harmful algal blooms. These algal
blooms, in turn, lead to depleted oxygen
conditions as they decay (Helfman 2007,
p. 176). The State of Idaho adopted
guidelines from EPA that monthly
averages of total phosphorus should not
exceed 0.05 milligram per liter (mg/L) in
streams that enter a lake or reservoir and
0.1 mg/L in any stream or other flowing
water to avoid eutrophication (IDEQ
2010, p.1).
Trapper Creek, a stream that enters
Oakley Reservoir, is currently listed on
Idaho’s 303(d) list for phosphorous and
sediment (Lay 2003, p. 45). Although
total phosphorus levels exceeded
guidelines in Trapper Creek in almost
all sampling events, there was little
evidence of eutrophication (nuisance
algae growth) (Lay 2003, p. 68).
Beaverdam Creek exceeded the 0.1 mg/
L total phosphorus limit in 16 out of 41
sampling events (39 percent) in 2001
(Lay 2003, p. 45). Although no
eutrophication has been seen, these
results suggest that eutrophic conditions
could affect aquatic habitats in the
future.
Fish need adequate dissolved oxygen
in the water to breath. At extremely low
oxygen levels, fish suffocation is
possible; however, it is very uncommon,
as fish have evolved a number of
mechanisms to escape this fate (Kramer
1987, p. 81). More common nonlethal
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effects of reduced dissolved oxygen
include reduced growth rates and
greater susceptibility to bird predators
(fish approach water surface for higher
oxygen water and are more easily
identified by birds) (Kramer 1987, p.
82). Idaho established a dissolved
oxygen minimum concentration of 6
mg/L (Lay 2003, p. 48). This limit
considers salmonid spawning
requirements (Lay 2003, p. 48) and is
likely adequate for northern leatherside
chub. Dissolved oxygen levels are not
specifically considered to be impaired
for Trapper Creek (IDEQ 2010, p. vii)
and are likely sufficient to fully support
aquatic life, including the northern
leatherside chub. It is likely that
northern leatherside chub can persist in
periodic, short-term, low dissolved
oxygen situations because they have
been documented to persist in isolated
pool environments even after other
species have perished (Belk and
Johnson 2007, pp. 70–71). It is unclear
how they would respond to low
dissolved oxygen in the long term, as
dissolved oxygen is a key attribute for
fish health. However, unless conditions
were severe, we would expect any low
dissolved oxygen events to be shortterm in nature.
Sediment in the water column, also
called Total Suspended Solids (TSS),
affects fish by reducing feeding abilities
(rate and success), degrading habitat
(filling interstitial substrate space), and
removing oxygen (Newcombe and
Jensen 1996, pp. 694–695). Sediment
pollution can come from various
sources, including, but not limited to,
grazing, mining, and dirt roads.
Hatchery experiments showed that
northern leatherside chub prefer cobble
substrates with adequate interstitial
space for egg deposition (Billman et al.
2008a, p. 278), and field research
determined that northern leatherside
chub feed on insects in both the water
column and the stream substrate (Bell
and Belk 2004, p. 414). High sediment
loads could interfere with the natural
ecology (e.g., feeding and reproduction)
of the northern leatherside chub through
sedimentation of spawning and feeding
habitats. Correspondingly, microhabitat
analysis does indicate that sand-silt
substrate is negatively associated with
leatherside chub presence and
leatherside chub are more abundant at
locations with gravel substrate (Wilson
and Belk 2001, p. 40). However, this
analysis did not include any of the large
populations now known to inhabit
degraded areas, such as Muddy and
Upper Twin Creeks, and included only
one population now known as northern
leatherside chub (Trapper Creek, which
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is impacted by other ecological factors
as well as sediment pollution; the other
populations analyzed were southern
leatherside chub) (Wilson and Belk
2001, p. 38). Because many of the
populations of northern leatherside
chub persist in degraded areas and no
data exist to clearly link sediment with
negative impacts, we conclude that
sediment alone is not a threat to
northern leatherside chub. However,
sediment may act in conjunction with
other impacts to threaten populations.
Limits of 25 mg/L TSS will provide a
high level of protection for aquatic
organisms and 400 mg/L TSS will
provide low protection (Lay 2003, p.
47). Idaho uses a monthly average of 50
mg/L TSS and a daily maximum of 80
mg/L TSS as the upper limits for
sediment (Lay 2003, p. 47). Both
Trapper Creek and Beaverdam Creek
exceeded daily maximum and monthly
average limits for TSS in 2001.
Sediment levels in Trapper Creek are
highest following runoff events in the
spring (March-May) (IDEQ 2010, p. 6),
and appear to negatively affect
salmonids in the lower sections of
Trapper Creek (Lay 2003, p. 68). One
event, from September 2001,
documented a monthly average of 1,649
mg/L TSS in Beaverdam Creek, which is
about 33 times the established Idaho
threshold (Lay 2003, p. 102). Elevated
TSS conditions such as this may cause
low reproductive or feeding success by
filling in substrate used for both egg
deposition and macroinvertebrate
habitat and reducing visibility for
northern leatherside chub.
Thermal pollution (unnatural water
temperatures) can affect fish by altering
metabolism and stressing biological
norms. Thermal limits are unique for
each fish species. Idaho has established
an upper temperature standard of 22 °C
(72 °F) for an instantaneous limit and 19
°C (66 °F) as a daily average for cold
water biota (IDEQ 2010, p. 11). We
determined that these temperature
thresholds are adequately conservative
for northern leatherside chub (Lay 2003,
pp. 38–39). Northern leatherside chub
can tolerate higher stream temperatures
than salmonids, are documented to
persist in streams as high as 23 °C (73
°F) (Isaak and Hubert 2001, p. 27), and
have an upper incipient lethal
temperature of 26 to 30 °C (79 to 86 °F)
(as temperatures are increased in a tank,
this is the temperature at which 50
percent die) (Billman et al. 2008b, pp.
463, 468–469). Beaverdam Creek has
reached daily averages of 19.32 °C
(66.78 °F) and 21.75 °C (71.15 °F),
although we do not consider these
temperatures to be outside the thermal
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tolerance range for northern leatherside
chub.
Water-quality issues have been
documented in Beaverdam and Trapper
Creeks within the Goose Creek subbasin,
although aquatic communities in each
of these creeks still persist. For example,
macroinvertebrate communities in
Trapper Creek and the upper portions of
Beaverdam Creek were considered
healthy, and the fish community
included species believed to tolerate
moderately impaired water quality (Lay
2003, pp. 99–100). However, the
macroinvertebrate community in lower
Beaverdam Creek was indicative of poor
water quality. Although Trapper Creek
does not harbor native trout normally
associated with cool water systems (Lay
2003, pp. 67, 68), Trapper Creek has
been shown to support the designated
beneficial uses of cold-water biota and
salmonid spawning (IDEQ 2010, p. 9).
In summary, impaired water quality
(based on 303(d) lists from the various
States) affects the habitat of two
populations of northern leatherside
chub rangewide (Beaverdam and
Trapper Creeks), both in the Idaho
portion of the Goose Creek subbasin
(Snake River subregion), although we
know of no specific information on how
impaired water quality may affect the
species. Levels of total phosphorus and
suspended sediment have been elevated
in these streams and resulted in
correspondingly low dissolved oxygen
levels. Because research cited above
demonstrates that elevated sediment,
elevated phosphorus, and reduced
dissolved oxygen affect fish life-history
traits, such as reducing reproductive
success (from clogged interstitial space),
decreasing feeding success (through
impacts to macroinvertebrates), or
restricting growth (from low dissolved
oxygen levels), it is possible that these
conditions have depressed population
abundance in these streams.
Only 2 of 14 populations occur in
water-quality-impaired streams and
these streams are not known to be lethal
to aquatic biota. We found no
information that water quality may act
on this species to the point that the
species itself may be at risk, nor is it
likely to become so.
Fragmentation and Isolation of Existing
Populations
The arrangement, or interconnected
nature, of species occurrences is
especially important when assessing
species vulnerability, because numerous
studies link habitat fragmentation to
population declines and increased
extinction risk (Dunham et al. 1997, p.
1126; Fagan et al. 2002, p. 3250; Fagan
et al. 2005, p. 34 and references therein).
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Human modifications to stream systems
in the western United States, such as
reservoir creation, nonnative fish
introductions, and irrigation practices,
fragment native fish distributions
(Dunham et al. 1997, p. 1128;
Hilderbrand and Kershner 2000, p. 513),
including those of the northern
leatherside chub (UDWR 2009, pp. 5,
31). In the western United States,
physical barriers to dispersal (i.e., dams
or culverts) and unsuitable habitat (i.e.,
lakes, dewatered stretches, or areas with
increased predator abundance) are the
most common agents of stream
fragmentation (Fagan et al. 2002, p.
3255).
Fragmentation of stream systems is
unique, because unlike terrestrial
organisms, fish species are limited to
movement through the stream corridor
and cannot simply move around an
obstruction such as a dam (Neraas and
Spruell 2001, p. 1153; Fagan 2002, p.
3243). Because stream fragmentation is
often caused by impassable barriers,
such as dams or lakes, fish populations
become isolated. Whether it is the result
of human alterations or natural
patchiness in habitat, isolation of local
populations increases the risk of
extirpation events because immigration
and recolonization events, ‘‘rescue
effects,’’ are precluded (Stacey and
Taper 1992, p. 26; Dunham et al. 1997,
p. 1131; Fagan et al. 2002, p. 3250).
When new individuals are unable to
enter into an area to supplement
declining populations or to re-establish
a population after a catastrophic
extirpation event, it is much more likely
the population will disappear
permanently. It has been demonstrated
that the overall number of occurrences
of a species is less important to
extinction risk than the fragmentation of
occurrences when other variables
remain constant (abundance, etc.), with
species having a few clustered,
interacting populations being less
vulnerable to extinction than a species
with many, isolated populations (Fagan
et al. 2002, p. 3254).
It is important to consider the species’
mobility and colonization ability when
fragmentation is discussed. For many
freshwater fish species, most individual
fish do not emigrate from their resident
home area, but those that do tend to
move great distances (Fagan et al. 2002,
p. 3255). These long-distance dispersers
are likely the primary mechanism for
the quick recolonization of extirpated
stream reaches (Peterson and Bayley
1993, p. 199). We know that the
surrogate species southern leatherside
chub follows this pattern, with many
individuals having high site fidelity, but
a small cohort (not dependent on
individual size) moving long distances
for a small minnow species (0.5 to 2 km
(0.3 to 1.25 mi)) over short time spans
(within 1 year) (Rasmussen 2010, pp.
42, 48–49). Based on similar physical
capabilities and life histories, it is likely
that northern leatherside chub can move
similar distances. This ability to move
provides a mechanism for individuals to
leave unsuitable habitat when
conditions warrant and to emigrate to
new areas for natural demographic
reasons.
We conclude that when suitable
migratory corridors exist, northern
leatherside chub will successfully use
them. Supporting this conclusion, the
collection of individual northern
leatherside chub throughout habitats
downstream of known populations may
indicate that either yet undocumented
populations exist or individuals are
migrating into new habitats. Regardless
of the distinction, the collection of
individual northern leatherside chub
found large distances away from known
populations, as defined in this finding,
supports the conclusion that northern
leatherside chub can move large
distances when suitable pathways exist.
For example, collections of individuals
in lower Sulphur Creek and the
mainstem Bear River are between 17
and 29 km (10.5 and 18 mi) downstream
of the Yellow Creek population and
between 11 and 19 km (7 and 12 mi)
from the Upper Mill/Deadman Creeks
population (approximate distances)
(McAbee 2011, p. 6). The occurrence of
individuals many kilometers
downstream in the large interpopulation corridor (whether they be
resident or emigrants) supports a
conclusion that these two populations
could potentially interact because
individual presence demonstrates a
suitable, occupied pathway exists and is
being used. Additionally, individuals
collected downstream of the Rock Creek
population were between 8 and 13 km
(5 and 8 mi) away from the population
center (Colyer and Dahle 2010, p. 5),
which is a distance similar to that
separating the Rock Creek and Upper
Twin Creek populations. Similarly,
individuals entrained in irrigation
canals were 8 km (5 mi) downstream of
the Muddy Creek population (Roberts
and Rahel 2008, p. 951). Finally,
individuals collected in mainstem
Goose Creek were between 6 and 18 km
(4 and 11 mi) downstream of the
Beaverdam Creek population, which is
distance similar to that separating the
Trout Creek population from Beaverdam
(in the opposite direction). Therefore,
based on our knowledge of the northern
leatherside chub’s movement ability and
based on the occurrence of individuals
many kilometers downstream of extant
populations, we conclude that
populations separated by moderatedistance (up to about 48 km (30 mi)),
barrier-free corridors are able to interact
(Table 6).
TABLE 6—SUMMARY OF FRAGMENTATION FOR EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS
NATIONAL HYDROGRAPHY DATASET
LOCATIONS
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Upper Bear .............
Connected to another population
Multiple occurrences
Occurrences within population
Upper Mill/Deadman
Creeks.
Upper Sulphur/La
Chapelle Creeks.
Yellow Creek ..........
UT/WY
Yes .........................
Yes .........................
WY
No ...........................
Yes .........................
UT/WY
Yes .........................
Yes .........................
WY
WY
Yes .........................
Yes .........................
Yes .........................
No ...........................
Throughout Mill Creek (UT & WY);
Deadman Creek.
Upper Sulphur Creek; La Chapelle
Creek.
Throughout Yellow Creek (UT & WY);
Thief Creek.
Clear Creek; North Fork Twin Creek.
Rock Creek.
Dry Fork Smiths
Fork.
Muddy Creek ..........
WY
No ...........................
No ...........................
Dry Fork Smiths Fork.
WY
Yes .........................
Yes .........................
Muddy Creek; Mill Creek.
Pacific Creek ..........
Jackknife Creek ......
WY
ID
No ...........................
No ...........................
No ...........................
Yes .........................
Pacific Creek.
Jackknife Creek; Squaw Creek; Trail
Creek.
Subbasin
Bear River ...............
State
Upper Twin Creek ..
Rock Creek ............
Subregion
Population name
Central Bear ...........
Snake River ............
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63459
TABLE 6—SUMMARY OF FRAGMENTATION FOR EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS—Continued
NATIONAL HYDROGRAPHY DATASET
LOCATIONS
Subregion
Population name
State
Connected to another population
Multiple occurrences
Occurrences within population
Subbasin
Goose Creek ..........
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Green River .............
Trapper Creek ........
Beaverdam Creek ..
Trout Creek ............
ID
ID
NV/ID
No ...........................
Yes .........................
Yes .........................
No ...........................
No ...........................
No ...........................
Trapper Creek.
Beaverdam Creek.
Trout Creek.
Upper Green River/
Slate Creek.
Blacks Fork ............
North Fork Slate
Creek.
Upper Hams Fork ...
WY
No ...........................
Yes .........................
North Fork Slate Creek; Slate Creek.
WY
No ...........................
Yes .........................
Upper Hams Fork; West Fork Hams
Fork.
When analyzing the potential threat of
fragmentation of northern leatherside
chub, we considered two patterns of
isolation. First, we assessed the
distribution of populations (defined in
this finding as an individual or set of
12-digit HUC(s)) across the species’
range. For example, we can say that the
Jackknife and Pacific Creek populations
are isolated from other populations over
the range, but the Upper Twin Creek
and Rock Creek populations can interact
with each other (Table 6). Second, we
assessed the occurrences of individuals
within the population boundaries, or,
more simply stated, how widespread
individuals are within the population
boundary. For example, we can say that
the Pacific and Rock Creek populations
have one local occurrence, but that the
Jackknife and Upper Twin Creek
populations have multiple occurrences
within one population boundary (Table
6). In other words, the Jackknife Creek
population has a more continuous
distribution within the subwatershed,
while the Pacific Creek population is
isolated to one area.
This two-tiered approach lets us
determine the overall extirpation
(localized extinction) risk to
populations because catastrophic events
can range in scale from the entire
population area to smaller areas within
the population. In the above population
isolation example (Jackknife and Pacific
Creeks vs. Upper Twin and Rock
Creeks), there are no nearby populations
to recolonize the Jackknife or Pacific
Creek populations if all individuals died
from a large-scale disturbance. However,
if all individuals in the Rock Creek
population died, downstream emigrants
from the Upper Twin Creek population
could recolonize the area. In the second
example, if a catastrophic event affected
only part of the Jackknife Creek
population (such as the Squaw Creek
tributary) and all individuals died, the
area could be recolonized by another
occurrence (such as the Trail Creek
tributary). However, if a catastrophic
event affected the single occurrence in
Pacific Creek and killed all individuals,
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the entire population would be
extirpated.
For this finding, we classified each
population as either isolated or not
isolated based on known barriers
preventing movement into the
population (reservoirs, culverts (Aedo et
al. 2009, p. 1), or impassable stream
distances) (Table 6). If a population
could interact with at least one other
population, we considered it not
isolated. Also, we focused only on
permanent barriers, such as large
reservoirs or stream distances, instead of
temporary barriers, because we assumed
permanent barriers will never be
bypassed, but temporary barriers could
be bypassed at a low frequency with
proper conditions. For example,
dewatered stretches were not
considered a large scale barrier, because
in wetter years and wetter seasons they
may carry enough water for bypass.
Conditions for recolonization or
immigration need to occur only
sporadically to repopulate areas devoid
of fish. Finally, we focused on barriers
affecting dispersal only into the
population, because we are primarily
concerned with recolonization of
extirpated areas.
Large reservoirs isolate three
populations of northern leatherside
chub: Trapper and Jackknife Creeks in
the Snake River subregion; and Upper
Sulphur/La Chapelle Creeks in the Bear
River subregion. Large stream distances
isolated three additional populations
from all other populations: Pacific Creek
in the Snake River subregion; and North
Fork Slate Creek and Upper Hams Fork
in the Green River subregion.
Impassable culverts isolated one more
population: Dry Fork Smiths Fork in the
Bear River subregion (Trout Unlimited
2010a, p. 7–8). The other seven
populations were considered connected
to at least one other population.
Populations connect primarily in pairs:
Muddy Creek and Dry Fork Smiths Fork
(Dry Fork Smiths Fork is isolated from
Muddy Creek, but not vice versa
because culverts are impassable only in
the upstream direction); Yellow and
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Upper Mill/Deadman Creeks; and Rock
and Upper Twin Creeks in the Bear
River subregion; and Beaverdam and
Trout Creeks in the Snake River
subregion. These results are
summarized in Table 6.
We next determined if each
population contained multiple
occurrences within the population
boundary. We considered a population
to have multiple occurrences if multiple
tributaries were occupied or northern
leatherside chub were in divergent areas
of the same stream (separated by at least
10 km (6 mi) of approximate stream
distance). Of the 14 northern leatherside
chub populations, 3 (Pacific and
Trapper Creeks in the Snake River
subregion, and Dry Fork Smiths Fork in
the Bear River subregion) are isolated
and likely contain only one occurrence,
making them vulnerable to a large-scale
disturbance or stochastic event.
The Trapper Creek population occurs
in an upstream tributary to Oakley
Reservoir. Oakley Reservoir, and other
reservoirs, act as ‘‘environmental
filters,’’ preventing movement of smallbodied fish between tributaries and
fragmenting distributions (Matthews
and Marsh-Matthews 2007, p. 1042).
Given the difference in stream and lake
habitats, and the presence of largebodied predators in most reservoirs, we
believe it is unlikely that northern
leatherside chub could survive
migrating through Oakley Reservoir
because it supports large populations of
piscivorous (fish-eating) rainbow trout
(Oncorhynchus mykiss) and walleye
(Sander vitreus) (IDFG 2010a, p. 2;
2010b, p. 3). We are not aware of other
northern leatherside chub populations
that are located in direct tributaries to
a reservoir.
Within the Bear River subregion,
culverts surrounding the Dry Fork
Smiths Fork population likely prevent
any immigration of northern leatherside
chub into the population, but do not
prevent emigration of individuals out of
the population, as the barriers primarily
prevent upstream movement. However,
the large population size upstream of
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these culverts indicates that these
barriers have not caused a quantifiable
impact to population size. In fact, these
barriers may be preventing downstream
nonnative trout from entering the area,
thus protecting the population.
Alternatively, these barriers may be
causing genetic isolation that could
negatively impact the population.
Rangewide, 7 of the 14 northern
leatherside chub populations are
isolated, which increases risk to largescale disturbances or stochastic events,
such as extreme drought, large wildfire,
or invasion of nonnative species (Table
6). Four of the seven have multiple
occurrences within the population,
offering the potential for rescue effect
dynamics. In fact, this situation may
have recently played out in the
Jackknife Creek population, where a
wildfire in 1991 burned a significant
portion of the sub-watershed, but did
not affect upstream portions of Squaw
Creek (Isaak and Hubert 2001, pp. 26–
27). It is possible that northern
leatherside chub either retreated to
suitable habitat within Squaw Creek
during and after the fire, or that
emigrants from Squaw Creek
recolonized other portions of Jackknife
Creek.
In summary, isolation and
fragmentation of northern leatherside
chub populations in stream systems can
substantially reduce recolonization
potential, and increase the risk of a local
extirpation event due to a large-scale
disturbance or stochastic event (Fagan et
al. 2002, p. 3255). When migratory
pathways exist, fish species tend to
quickly recolonize a stream (Peterson
and Bayley 1993, p. 199). However, in
desert systems, human modifications
have reduced opportunities for
recolonization, eliminating the natural
counterbalance against extirpation
(Fagan et al. 2002, p. 3255). Populations
able to interact, such as closely
distributed populations, are more likely
to persist because clustered occurrences
increase the probability of
recolonization (Fagan et al. 2002, p.
3255).
Two fragmented populations of
northern leatherside chub, Trapper and
Pacific Creeks in the upper Snake River
subregion, are isolated from other
populations and are vulnerable to
stochastic events, including local
disturbances, such as disease, pollution,
or floods. Conversely, we believe the
isolated Dry Fork Smiths Fork
population is not as vulnerable to a
stochastic event due to its relatively
large population and its isolation (due
to culverts surrounding the population),
which is precluding the migration of the
predatory nonnative brown trout into its
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habitats. Other isolated populations are
not impacted by fragmentation (Upper
Sulphur/La Chapelle Creek; North Fork
Slate Creek; Upper Hams Fork), but
their isolation puts them at an increased
risk from other large-scale threats and
stochastic events. We found no
information that fragmentation may act
on this species to the point that the
species itself may be at risk, nor is it
likely to become so.
Summary of Factor A
We found no information that
livestock grazing, oil and gas
development, mining, water
development, water quality, or
fragmentation of populations may act on
this species to the point that the species
itself may be at risk, nor is it likely to
become so. While these factors
individually have been shown to affect
one or a few extant populations of
northern leatherside chub, none is
considered a significant threat to the
species’ persistence. For example,
stable, reproducing northern leatherside
chub populations occur at many
locations where degraded habitat
conditions exist. While these habitat
characteristics may not be optimal for
northern leatherside chub populations,
their continued persistence and
successful reproduction demonstrate
that they have some level of tolerance
for less than optimal environmental
conditions. Because of the sufficient
number of populations, the interaction
between several population locations,
and the large size of many populations,
we conclude that local extirpation risk
to a small number of populations does
not constitute a substantial threat to the
species. The best scientific and
commercial information available
indicates that rangewide the northern
leatherside chub is not threatened by
the present or future destruction,
modification, or curtailment of its
habitat or range, nor is it likely to
become so.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Commercial, recreational, scientific,
and educational utilizations are not
common northern leatherside chubrelated activities, and protections are in
place to limit their effect on the species.
The use of live baitfish, including
northern leatherside chub, is not
permitted in the species’ range (Harja
2009, p. 4; Miller et al. 2009, p. 3;
UDWR 2009, p. 32). In addition, we are
aware of no evidence that northern
leatherside chub are being illegally
collected for any purposes.
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Across the northern leatherside
chub’s range, permits are required to
collect the species for any reason.
Individuals have been collected for
genetic analysis from various
populations across the species’ range
(Northern Leatherside Chub
Conservation Team 2011, p. 4). These
collections were permitted under each
State’s regulatory authority (see below),
and because they are a small portion of
the local population, should not
negatively impact local population
persistence.
Northern leatherside chub are
considered a ‘‘prohibited’’ species under
Utah’s Collection, Importation, and
Possession of Zoological Animals Rule
(R–657–3–1), which makes it unlawful
to collect, import, or possess northern
leatherside chub without a permit (Harja
2009, p. 4). Use of the species for
scientific or educational purposes also
is controlled by the UDWR, and the
agency reviews requests to make sure
that no negative population impacts will
occur (Harja 2009, p. 4). Recently,
northern leatherside chub were
collected for a hatchery population
housed in Logan, Utah (Billman et al.
2008a, p. 274), and future collections
will be required for this population to
persist (Northern Leatherside Chub
Conservation Team 2010, p. 5).
However, the number of northern
leatherside chub taken for scientific and
educational purposes is low (UDWR
2009, p. 32).
The species is considered ‘‘protected
non-game’’ under Idaho’s Rules
Governing Classification and Protection
of Wildlife (IDAPA 13.01.06), which
makes it unlawful to take or possess
northern leatherside chub except with a
permit under Rules Governing the
Importation, Possession, Release, Sale,
or Salvage of Wildlife (IDAPA 13.01.10)
(Schriever 2009, p. 1). In Wyoming, a
rigorous collection permitting system
restricts commercial, scientific, and
educational activities (Miller et al. 2009,
p. 3). Small-scale permits are given to
local residents to seine the Bear River
drainage for baitfish (dead), but these
few permits are not impacting
populations of northern leatherside
chub (Miller et al. 2009, p. 4). Northern
leatherside chub is not a protected
species in Nevada. However, the Nevada
Department of Wildlife (NDOW)
regulates collections of northern
leatherside chub through a permitting
process (Johnson 2011a, pers. comm.).
Summary of Factor B
Northern leatherside chub are not
overutilized for commercial,
recreational, scientific, or educational
purposes. A limited number of northern
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leatherside chub are collected from wild
populations for hatchery augmentation
or scientific investigation purposes, but
the level of collection is very small. The
best scientific and commercial
information available indicates that the
northern leatherside chub is not
threatened by overutilization for
commercial, recreational, scientific, or
educational purposes, nor is it likely to
become so.
Factor C. Disease or Predation
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Disease and Parasitism
Disease and parasitism do not affect
northern leatherside chub to a
significant degree. It is likely that the
species encounters natural diseases and
parasites. However, we are not aware of
any extant, wild population that was
substantially impacted by a disease or
parasite; no research project or
collection effort has documented a
disease or parasite problem.
There is no discussion of disease or
parasites in the threats section of the
Rangewide Conservation Agreement and
Strategy for Northern Leatherside Chub
(described in detail under Factor D
below) (UDWR 2009, p. 32). However,
one of the conservation elements in the
Conservation Agreement and Strategy is
‘Disease Management,’ the goal of which
is to determine the extent of infections,
monitor any known infections, and
prevent further infections by
implementing biosecurity protocols
(UDWR 2009, p. 37). An example of
disease management already occurred in
Utah, where UDWR raised a broodstock
of wild northern leatherside chub and
used progeny to repatriate (reintroduce
a population) multiple sites (McKay et
al. 2010, p. 1–3). Fishes brought into the
hatchery setting were treated for
internal and external parasites (Billman
et al. 2008a, p. 274), ensuring that all
restocked and progeny fish are
pathogen-free (Harja 2009, p. 4). The
UDWR also minimizes within-hatchery
diseases, as demonstrated by their
efforts to disinfect eggs for maximum
survival (FES 2010, pp. 25, 26).
There are no known disease or
parasite problems for the northern
leatherside chub. We found no
information that disease or parasites
may act on this species to the point that
the species itself may be at risk, nor is
it likely to become so.
Predation
Northern leatherside chub are small
minnows, and as such, are prey for
larger fish and sometimes birds (Sigler
and Sigler 1996, pp. 77–78).
Historically, the main piscivorous (fisheating) predator in northern leatherside
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chub habitats was cutthroat trout—
Bonneville cutthroat trout
(Oncorhynchus clarkii utah) in the Bear
River subregion, and Yellowstone
cutthroat trout (Oncorhynchus clarkii
bouvieri) in the upper Snake River
subregion (Greswell 1995, pp. 42–43;
May and Albeke 2005, p. 20; Nannini
and Belk 2006, p. 458; May et al. 2007,
p. 15). However, these subspecies likely
exerted moderately weak predation
pressure on northern leatherside chub
over much of their evolutionary history
because cutthroat trout only become
primarily piscivorous at larger sizes,
when they tend to inhabit larger river
systems where northern leatherside
chub are typically not found (Walser et
al. 1999, p. 276; Nannini and Belk 2006,
pp. 458–459).
Weak predation pressure over
evolutionary timescales often results in
species losing strong antipredator
responses, which in fish species
includes escape (strong burst speeds) or
concealment (effective camouflage)
(Nannini and Belk 2006, pp. 453, 460).
In contrast, short timescale adaptations
to predation pressure include habitat
shifts or populations of lower carrying
capacity. Meeting this expectation,
southern leatherside chub have slow
and non-complex escape responses
(Nannini and Belk 2006, p. 460) and
respond to intense predation by shifting
habitat usage (Walser et al. 1999, p.
272). Southern leatherside chub may be
more vulnerable to predation risks than
other native minnows because they lack
effective predator responses, making
them a preferred prey (Nannini and Belk
2006, p. 460).
Because they share similar ecological
niches, such as habitat associations
(Belk and Wesner 2010, p. 12) and
native predators, we expect that
northern leatherside chub have predator
responses similar to southern
leatherside chub and also are likely
vulnerable to predation. By losing
effective antipredator responses,
northern leatherside chub were able to
divert more energy to other life-history
characteristics, such as foraging,
reproduction, and growth (Nannini and
Belk 2006, p. 460). This adaptation
produces benefits under natural,
evolutionarily historical conditions
where northern leatherside chub
primarily coexisted with other smallbodied fish and cutthroat trout species,
but places it at a disadvantage when
encountering highly predatory species.
One such predatory species is brown
trout. Native to Europe and western
Asia, brown trout is an introduced
predator that was widely stocked
throughout the United States for its
value as a sportfish (Sigler and Sigler
PO 00000
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1996, p. 205; Stoddard et al. 2005, pp.
11–12). Brown trout are highly
predatory to the detriment of native fish
communities, often out-competing and
preying on native predators, while also
consuming many small, native fish
species (Garman and Nielsen 1982, p.
862; Behnke 1992, p. 54; Wang and
White 1994, p. 475; Walser et al. 1999,
p. 272; Budy et al. 2005, pp. xii–xiii,
58–73). Brown trout are now commonly
distributed throughout adequate
habitats in the Bear and upper Snake
River subregions and have affected
native fish in these areas. They have
displaced native cutthroat species (Budy
et al. 2005, p. xii), limiting cutthroat
trout populations to mostly headwater
streams where temperatures are
generally too cold for brown trout
survival. Therefore, it is likely that this
introduced predator reduced the
historical range of northern leatherside
chub.
The closely related southern
leatherside chub has altered habitat
selection because of predation pressure
by brown trout (Walser et al. 1999, p.
272). This outcome is not surprising,
given that: (1) Piscivory is a dominant
factor shaping fish community structure
in stream ecosystems (Jackson et al.
2001, p. 157); (2) other prey species
retreat to safer periphery habitat when
faced with predation risks (Fraser et al.
1995, p. 1466); and (3) introduced
populations of brown trout have
affected native species worldwide
(McDowall 2003, pp. 230–231). For
example, in Diamond Fork Creek, Utah,
southern leatherside chub inhabited less
suitable, lateral habitats (cutoff pools
and backwaters) when the main channel
contained brown trout, despite the
presence of suitable main channel
microhabitats (Walser et al. 1999, p.
272). Because unoccupied main channel
habitats were identical to those
occupied in streams without brown
trout, it is likely that southern
leatherside chub select poorer quality
habitat to avoid brown trout predation
(Walser et al. 1999, p. 275). This
hypothesis was confirmed on a broad
geographic scale. In areas where brown
trout populations overlapped with
juvenile mountain sucker (Catostomus
platyrhynchus) and southern leatherside
chub, the latter two species used
backwaters and cut-off pools almost
exclusively, whereas in the absence of
brown trout, they commonly used main
channel pools (Olsen and Belk 2005, pp.
501, 503). This suggests that predation
is an important factor affecting habitat
use by small native fish, limiting them
to areas of less suitable habitat.
Although considered poorer habitats
than the main channel, lateral areas
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likely offer native fish their only chance
of persistence, because brown trout will
prey on individuals in main channel
habitats. Therefore, it is important to
preserve lateral habitats where northern
leatherside chub and brown trout
overlap, because even with brown trout
present, small native fish can survive
with adequate habitat complexity (Olsen
and Belk 2005, p. 504). Side channel
habitats are only available in natural
systems with adequate flow, not
degraded or simplified systems, such as
de-watered or channelized streams
(Olsen and Belk 2005, p. 504). In the
event that refuge areas are not available,
it is not likely that northern leatherside
chub populations can persist under
such heavy predation pressure.
Based on an analysis of brown trout
and southern leatherside chub, we
expect that when refuge habitat is not
available, brown trout predation exerts
direct mortality on northern leatherside
chub. Stream experiments revealed that
southern leatherside chub are 16 times
more likely to survive if brown trout are
absent than if present (Nannini and Belk
2006, p. 458), which explains why
lateral habitats are a safer option. For
example, in Diamond Fork Creek,
southern leatherside chub were absent
in upstream areas without lateral
habitats in 1999 (Walser et al. 1999, p.
276). Later, when flows were
permanently reduced throughout
Diamond Fork Creek by a water
conveyance pipeline, lateral habitats
disappeared completely and southern
leatherside chub were soon extirpated
from the entire system, presumably from
brown trout predation (Hepworth and
Wiley 2007, pp. 3–4).
Although brown trout and northern
leatherside chub can co-occur, the
presence of brown trout potentially
impacts northern leatherside population
densities in 3 of 14 populations
(Jackknife Creek, Dry Fork Smiths Fork,
and Muddy Creek). Brown trout were
negatively correlated with the
probability of encountering southern
leatherside chub over many tributaries
in the Sevier River drainage (Wilson and
Belk 2001, p. 39). Areas with high
densities of southern leatherside chub
were always free of brown trout, and
areas where the two species overlapped
had consistent low densities of southern
leatherside chub (Wilson and Belk 2001,
p. 41). Low population densities are
likely a result of cumulative losses of
individuals to predation, preventing
populations from reaching carrying
capacity.
Even when brown trout do not inhabit
the same location as northern
leatherside chub, brown trout can exert
indirect pressure on the species by
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acting as a migration barrier. Effective
aquatic predators can act as a dispersal
barrier by killing prey (Fraser et al.
1995, pp. 1461, 1468). Therefore, the
predation pressure on main channel
habitats (Walser et al. 1999, p. 272) may
prevent northern leatherside chub from
moving between populations,
exacerbating an already fragmented
species distribution. However, like
resident fish, emigrants are more likely
to survive migrations when complex
habitat (through adequate water supply)
is available (Gilliam and Fraser 2001,
pp. 267, 270).
More broadly, predators can fragment
an otherwise consolidated distribution
of prey species, forcing the prey to
abandon otherwise habitable areas for
constricted peripheral locations (Fraser
et al. 1995, p. 1461). In fact, it is
possible that through past population
extirpations combined with current
migration impediments, brown trout are
the cause of the current fragmentation of
leatherside populations (Wilson and
Belk 2001, p. 41).
An analysis of the range contraction
of northern leatherside chub compared
to brown trout stocking offers some
insight into the relationship between the
two species (current fish stocking
policies are analyzed under Factor D).
Between 1975 and 2005, the States of
Utah and Wyoming stocked at least 2.28
million brown trout in the Bear River
subregion (IDFG 2010c, entire; UDWR
2010, pp. 1–747; WGFD 2010, pp. 1–10).
Recent surveys indicate that no extant
northern leatherside chub populations
are in close proximity to the stocking
locations (Service 2011, pp. 33–34).
While this could be simply an artifact of
suitable habitat or preferential stocking
locations, we conclude that the
instances of historical extirpation
combined with the ecological influences
described above suggest a more
causative effect.
Further support of this causative
effect is documented in Utah. Between
1981 and 2005, approximately 400,000
brown trout were stocked in the Little
Bear/Logan subbasin (UDWR 2010, pp.
1–747), where northern leatherside chub
historically occurred but are no longer
found (UDWR 2009, p. 42). Surveys of
historical northern leatherside chub
locations in the nearby Lower Bear
subbasin also yielded no northern
leatherside chub, but did document
large numbers of brown trout (UDWR
2009, p. 42). Although there are no
voucher specimens of northern
leatherside chub for these historical
locations, UDWR considers collections
in the Little Bear River (four preserved
skeletons) as reliable because of the
reputation of the collector (W.F. Sigler)
PO 00000
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(McKay 2011, pers. comm.). It is not
unreasonable to conclude that high
densities of brown trout removed
northern leatherside chub from these
locations.
Stocking of brown trout also occurred
in subbasins with extant northern
leatherside chub. Near the UtahWyoming border, Utah and Wyoming
stocked around 250,000 brown trout in
the mainstem Bear River from 1980 to
1997, and Wyoming stocked around
500,000 in Woodruff Reservoir from
1985 to 1997 (UDWR 2010, pp. 1–45;
WGFD 2010, pp. 7–10). These locations
centralize an area of unoccupied habitat
between the two sets of populations in
the Upper Bear subbasin. In the Salt
River subbasin, northern leatherside
chub no longer occur in any tributaries
stocked with brown trout. Lastly,
Wyoming stocked around 250,000
brown trout in Sulphur Creek Reservoir,
directly downstream of the Sulphur/
LaChapelle Creeks population before
2000 (WGFD 2010, pp. 3–6), possibly
isolating that population of northern
leatherside chub completely. Therefore,
it is possible that past stocking events
and subsequent migration of brown
trout shaped the current distribution of
northern leatherside chub and could
prevent many populations from
interacting in the future.
Within the Snake River drainage,
populations of northern leatherside
chub persist in at least two streams
where brown trout were historically
stocked. In the Goose Creek subbasin,
Nevada has not stocked brown trout
since 1950 (Johnson 2010, pers. comm.),
nor has Utah recently stocked any
nonnative trout (Schaugaard and
Thompson 2006, pp. 5–6). Idaho
stocked about 5,500 brown trout in
Trapper Creek in 1988 (IDFG 2010c, p.
10), but they did not persist, as rainbow
trout are the only salmonid recently
collected in the stream (Keeley 2010,
pp. 3–4). Leatherside chub and brown
trout also were found together at two
sites in Jackknife Creek, but brown trout
made up less than 6 percent of salmonid
abundance at both sites (Univeristy of
Wyoming 2010, pp. 1–4). In contrast, in
the Twin Creek drainage, where a solely
native fish community resides, two
northern leatherside chub populations
currently persist, with individuals in
many tributaries (Colyer and Dahle
2010, p. 5).
The presence of brown trout can
cumulatively intensify abiotic factors,
such as reduced water level from
drought or irrigation, or increased
stream temperature from climate change
(see discussion under Factor E). As was
demonstrated in Diamond Fork Creek,
reduced water levels force native, small-
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bodied fish from refuge habitat to main
channel habitat, where brown trout can
easily prey on them. In fact, brown trout
will prey on southern leatherside chub
preferentially over redside shiner
(Nannini and Belk 2006, p. 458). The
relationship between water level and
brown trout presence also potentially
impacts migration patterns. Water levels
do not affect prey fish movement in the
absence of predators; however, water
levels are an issue when predators are
present (Gilliam and Fraser 2001, p.
270). In other words, when stream levels
are low from drought or human use,
northern leatherside chub are predicted
to move freely if brown trout are absent,
but will likely not move if brown trout
are present. Water level is rendered
influential only when a predator is
present (Gilliam and Fraser 2001, p.
270).
Northern leatherside chub
populations can endure if brown trout
are absent or at very low densities.
However, based on the ecological
mechanisms described above and the
lack of strong overlapping distribution,
we conclude that future introduction of
brown trout into streams with extant
northern leatherside chubs, although
not currently anticipated, would likely
impact those populations.
Other salmonid species, both native
and nonnative, could impact northern
leatherside chub populations through
predation as well. Although not
normally as piscivorous as brown trout,
introduced rainbow trout impact native
fish communities worldwide
(Lintermans 2000 in Blinn et al. 1993,
p. 139; McDowall 2003, p. 231; Vigliano
et al. 2009, p. 1406). In fact, rainbow
trout likely influence habitat use,
behavior, and distribution of another
Lepidomeda species, the Little Colorado
spinedace (L. vittata) (Blinn et al. 1993,
pp. 141–142). The Little Colorado
spinedace is similar to northern
leatherside chub, in that it evolved
without strong predation pressure but is
now forced into suboptimal habitats by
an introduced predator (Blinn et al.
1993, p. 142). We conclude that the
introduction of rainbow trout also poses
a threat, albeit less than brown trout,
because rainbow trout exert similar
nonnative predation pressure on
northern leatherside chub.
Brook trout (Salvelinus fontinalis) are
another nonnative trout species
occurring in the northern leatherside
chub’s range. While brook trout are
commonly referred to as carnivorous,
voracious feeders, they primarily feed
on insects throughout their life but will
eat fish when possible (Sigler and Sigler
1996, p. 211). Amazingly, they are
known to eat amphibians, reptiles, and
mammals on rare occasions,
demonstrating their variable diet (Sigler
and Sigler 1996, p. 211). However, it is
important to note that even large brook
trout are not especially piscivorous
(Sigler and Sigler 1996, p. 211), making
them less of a predatory threat than
either brown or rainbow trout.
The most likely impact of brook trout
on northern leatherside chub is
competition for available resources.
Brook trout populations are known to
become locally overabundant to the
point that the size class of the
population is stunted and resources are
scarce (Sigler and Sigler 1996, pp. 212–
213). However, brook trout inhabit
coldwater habitats, such as cool, clear
headwater streams and spring-fed
streams and lakes (Sigler and Sigler
1996, p. 212). They seek water
temperatures of 10 to 14.4 °C (50 to 58
°F), high-gradient streams (3 to 6
percent), and gravel substrate (Sigler
and Sigler 1996, pp. 211–212; Nadolski
2008, p. 63). In contrast, northern
leatherside chub occupy streams with
higher temperatures (15.6 to 20 °C or 60
to 68 °F) (Sigler and Sigler 1996, p. 79),
prefer low stream gradients (0.1 to 4
percent (Wilson and Belk 2001, p. 39)),
and can tolerate sediment-laden habitats
(UDWR 2009, p. 27).
Based on available information, we
conclude that brook trout pose a very
limited threat to northern leatherside
chub even though brook trout occur
both upstream and concurrently with 6
of 14 northern leatherside chub
populations. Habitats that are occupied
by northern leatherside chub are likely
suboptimal for brook trout. While
populations of the two species overlap,
densities of brook trout are generally
low in these locations, while densities
of northern leatherside chub are
generally stable and relatively high. We
also conclude that upstream
populations of brook trout are not a
threat because many are characterized
by abundant, small individuals that are
not piscivorous and inhabit areas
unlikely to support northern leatherside
chub if they were removed (Nadolski
2008, pp. 78–79; WGFD 2009, p. 5). For
example, at Deadman Creek, brook trout
have seemingly overpopulated the
portions upstream of a dense northern
leatherside population (Nadolski 2008,
p. 78). However, the brook trout
population is comprised of small,
sedentary, non-piscivorous fish
(Nadolski 2008, p. 38; 2011 pers.
comm.). We note that this is the only
population where brook trout stomach
contents have been collected, and it
would improve our understanding of
the species if more investigations
studied the interactions between brook
trout and northern leatherside chub. As
discussed in more detail under Factor E
(climate change), predation impacts
from brook trout are not expected to
increase if climate change predictions
are accurate. Warming waters (either
from increased air temperatures or
drought conditions) may benefit
northern leatherside chub and harm
brook trout, as northern leatherside
chub are more tolerant and ecologically
adapted to warmer water temperatures.
The presence of native cutthroat trout
species poses a very limited risk to
northern leatherside chub persistence
because cutthroat trout are a natural
predator that does not exert excessive
predation pressure. In fact, conservation
actions that remove nonnative trout and
introduce native cutthroat will likely
produce beneficial effects to northern
leatherside chub through reduced
predation.
To fully assess the threat of nonnative
trout, we assessed the probability that
nonnative trout could currently alter
populations or invade existing northern
leatherside chub populations in the
future. Fish stocking policies have
recently changed, resulting in a large
reduction of brown trout stocking in the
area. An analysis of recent collection
data shows that nonnative trout
populations are nearby 8 of the 14
extant northern leatherside chub
populations, although the number is
reduced to only 5 when brook trout
(which are less piscivorous) are
excluded (Table 7).
TABLE 7—PRESENCE OF NONNATIVE SALMONIDS (BROOK, BROWN, AND RAINBOW TROUT) AND NATIVE CUTTHROAT
TROUT AT EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS
National Hydrography Dataset Boundaries
Presence of Salmonids
Population
Subregion
Bear River .....................
Upper Bear .........................
Nonnative
(brook, brown, or rainbow)
Upper Mill/Deadman Creeks .........
Brook trout upstream .....................
Subbasin
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Native
cutthroat
Yes.
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TABLE 7—PRESENCE OF NONNATIVE SALMONIDS (BROOK, BROWN, AND RAINBOW TROUT) AND NATIVE CUTTHROAT
TROUT AT EXTANT NORTHERN LEATHERSIDE CHUB POPULATIONS—Continued
National Hydrography Dataset Boundaries
Presence of Salmonids
Population
Subregion
Central Bear .......................
Snake Headwaters .............
Salt River ............................
Goose Creek ......................
Green River ..................
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Snake River ..................
Upper Green River/Slate
Creek.
Blacks Fork ........................
In the Bear River subregion, the only
populations accessible by nonnative
trout are the Dry Fork Smiths Fork,
Muddy Creek, and Upper Mill/Deadman
Creeks populations. Although the
Muddy Creek and Dry Fork Smiths Fork
populations do not currently have
nonnative trout in occupied northern
leatherside chub habitat, downstream
tributaries in the Smiths Fork drainage
(not occupied by northern leatherside
chub) contain brown and brook trout
(Roberts and Rahel 2008, p. 951; Trout
Unlimited 2010b, pp. 78–91, Table 6).
Muddy Creek is accessible to these
downstream populations, because there
is no barrier separating the areas (Colyer
and Dahle 2007, p. 8), but Dry Fork
Smiths Fork is isolated by impassable
culverts (Trout Unlimited 2010a, pp. 7–
8, 10–12). However, the aquatic habitat
in Muddy Creek is currently unsuitable
for brown trout, likely preventing their
colonization of the area. Brook trout are
currently found upstream of occupied
northern leatherside habitat in Deadman
Creek, but not in the rest of the system
(Nadolski and Thompson 2004, p. 3;
Nadolski 2008, p. 78; Belk and Wesner
2011, pp. 1–4).
Although Sulphur Creek Reservoir,
downstream of the Upper Sulphur/La
Chapelle Creeks population, contains
brown and rainbow trout, we conclude
they cannot access northern leatherside
chub habitat. Prior to 2000, the WGFD
stocked thousands of brown trout in
Sulphur Creek Reservoir (WGFD 2010,
pp. 3–6), creating a possible source for
colonization into the Upper Sulphur/La
Chapelle Creeks population. However,
no brown trout were collected in
upstream reaches occupied by northern
leatherside (Belk and Wesner 2011, pp.
VerDate Mar<15>2010
Nonnative
(brook, brown, or rainbow)
Upper
Sulphur/La
Chapelle
Creeks.
Yellow Creek .................................
Upper Twin Creek .........................
Rock Creek ....................................
Dry Fork Smiths Fork ....................
Muddy Creek .................................
Pacific Creek .................................
Jackknife Creek .............................
Trapper Creek ...............................
Beaverdam Creek .........................
Trout Creek ...................................
North Fork Slate Creek .................
No ..................................................
Yes.
No ..................................................
No ..................................................
No ..................................................
Brown & brook trout downstream
Brown & brook trout downstream
Brook trout present ........................
Brown trout downstream ...............
Rainbow trout present ...................
No ..................................................
No ..................................................
Brook trout upstream .....................
Yes.
Downstream.
Yes.
Downstream.
Downstream.
Yes.
Yes.
No.
No.
Yes.
No.
Rainbow present/Brook trout upstream.
No.
Subbasin
20:18 Oct 11, 2011
Jkt 226001
Upper Hams Fork ..........................
1–4). Brown trout have not moved
upstream likely because there are
abundant food resources in the reservoir
and habitat directly upstream of the
reservoir is degraded by irrigation return
flow (Amadio 2011, pers. comm.).
In the upper Snake River subregion,
nonnative trout co-occur with
leatherside chub in two of the five
populations and are downstream of
another population. Brown trout are
found in lower reaches of Jackknife
Creek and were previously shown to cooccur with northern leatherside chub
(Isaak and Hubert 2001, pp. 6, 27),
although more recently brown trout
were not found at occupied northern
leatherside chub sites (Keeley 2010, pp.
45–60). Although brook trout inhabit the
same reach of Pacific Creek occupied by
northern leatherside chub, they
generally use different habitats (Grand
Teton National Park 2009, p. 1).
Introduced rainbow trout are
documented in Trapper Creek (Keeley
2010, pp. 4–5), although information is
lacking on what if any impact they have
on the northern leatherside chub
population.
In the Green River subbasin, both
northern leatherside chub populations
occur downstream of brook trout
(WGFD 2009, pp. 1–5). In addition, low
densities of rainbow trout occur in the
Upper Hams Fork, but they are likely
not reproducing (WGFD 2009, pp. 1–3).
Summary of Predation
Nonnative predators, especially
brown trout, impact northern
leatherside chub populations. In the
presence of brown trout, leatherside
chub occupy lateral habitats that could
provide refuge against predation (Walser
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Native
cutthroat
et al. 1999, p. 272), likely reducing
reproductive and forage success. Brown
trout hold leatherside chub populations
at low density (Wilson and Belk 2001,
p. 41), likely because leatherside chub
are preferred prey (Nannini and Belk
2006, p. 458).
While the stocking of brown trout has
been greatly reduced in recent years in
several streams within the range of
northern leatherside chub, established
brown trout populations are likely
sustainable in many locations, as shown
in the Salt River subbasin (Isaak and
Hubert 2001, p. 6). Currently, the
distribution of brown and rainbow trout
overlaps with northern leatherside chub
populations only in a few locations
(Trapper Creek, Upper Hams Fork, and
the lowest portion of Jackknife Creek).
Any changes in current stream
conditions (i.e., changing water quality
and temperatures) could facilitate
upstream distributional shifts for these
nonnatives, putting northern leatherside
chub at increased risk of predation. For
example, if the projected changes in
climate warms waters across the
western United States (EPA 2008, p. 8),
brown trout could possibly move
upstream into currently occupied
northern leatherside chub habitats;
however, we have no specific
information to indicate that this is likely
to happen.
In summary, we found no information
that predation may act on this species
to the point that the species itself may
be at risk, nor is it likely to become so.
Most populations (9 of 14) do not share
habitats with nonnative trout of
concern, and 3 of 5 potentially impacted
populations occur where habitats are
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likely not suitable for salmonids (i.e.,
Muddy Creek), contain migration
barriers in the form of impassable
culverts (i.e., Dry Fork Smiths Fork), or
have only low densities of the nonnative
rainbow trout (i.e., Upper Hams Fork).
Therefore only two northern leatherside
chub populations (in the Snake River
subregion) may be vulnerable to the
effects of nonnative trout. However, we
have no information to indicate how the
species and its habitats have been
impacted. Brown trout occur in the
lower reaches of Jackknife Creek,
primarily downstream of northern
leatherside chub populations in warmer
waters (although they have been found
to co-occur in past samples). Rainbow
trout continue to co-occur with northern
leatherside chub in Trapper Creek
where the IDFG continues to stock
nonnative rainbow trout into Oakley
Reservoir. Because nonnative trout
impact a small proportion of
populations, predation does not act on
this species to the point that the species
itself may be at risk, nor is it likely to
become so.
Summary of Factor C
At this time we know of no
information that indicates that the
presence of parasites or disease
significantly affects northern leatherside
chub, or is likely to do so. There is
strong evidence that northern
leatherside chub can be impacted by
predation from nonnative trout,
especially brown trout. Nonnative trout
currently occur near or downstream to
5 of 14 northern leatherside chub
populations. While these populations
are more vulnerable to predation and
other effects from nonnative trout, we
have no information that indicates
nonnative trout are currently impacting
these populations or the species as a
whole. We found no information that
disease or predation may act on this
species to the point that the species
itself may be at risk, nor is it likely to
become so.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
The Act requires us to examine the
inadequacy of existing regulatory
mechanisms with respect to extant
threats that place northern leatherside
chub in danger of becoming either
endangered or threatened. Regulatory
mechanisms affecting the species fall
into three general categories: (1) Land
management; (2) State mechanisms; and
(3) Federal mechanisms.
Land Management
Land ownership in the entire upland
watershed affects aquatic habitats
because land activities distribute effects
downslope into the stream corridor.
Subwatersheds harboring populations of
northern leatherside chub are
distributed across BLM, private, State,
USFS, and National Park Service (NPS)
lands and incur varying regulatory
mechanisms depending on land
ownership (USFWS 2011, pp. 11–17).
The following section provides a brief
description of how land ownership
affects regulatory mechanisms where
extant northern leatherside chub
populations occur. We first analyze the
land ownership of the entire upland
area to analyze general effects, and then
analyze local riparian corridor
ownership to investigate more local
effects.
Currently occupied northern
leatherside chub streams are contained
in 14 populations based on
subwatersheds (HUC12) covering
approximately 242,864 hectares (938
square mi). Land ownership in occupied
subwatersheds is comprised of privately
owned land (31.5 percent in the States
of Idaho, Nevada, Utah, and Wyoming),
as well as lands managed by BLM (30
percent), NPS (3.5 percent), USFS (30.5
percent), and the States of Wyoming (4.3
percent) and Idaho (0.04 percent)
(Service 2011, pp. 11–17). Aside from
the subwatersheds in the Upper Bear
River subbasin (Upper Mill/Deadman
Creeks, Upper Sulphur/La Chapelle
Creeks, and Yellow Creek), which are
almost entirely privately owned, most
northern leatherside chub
subwatersheds are affected by upstream
lands that are managed by the BLM and
the USFS, or the NPS for Pacific Creek
(Table 8). However, more than threequarters of northern leatherside chub
subwatersheds have some, or their
entire, occupied habitat on private
lands, which typically encompasses the
wetted channel and the riparian buffer
surrounding the stream (Table 9).
TABLE 8—LAND OWNERSHIP BY PERCENT OF SUBWATERSHEDS (12-DIGIT HUC) WITH NORTHERN LEATHERSIDE CHUB
POPULATIONS
Upland watershed land ownership by entity
(% land owned)
Population name
BLM
Private
State
USFS
NPS
Bear River Subregion
Upper Mill/Deadman Creeks ........................................................................................
Upper Sulphur/La Chapelle Creeks .............................................................................
Yellow Creek ................................................................................................................
Upper Twin Creek ........................................................................................................
Rock Creek ..................................................................................................................
Dry Fork Smiths Fork ...................................................................................................
Muddy Creek ................................................................................................................
0
6
1
77
61
40
63
68
88
95
14
19
26
19
1
6
4
6
10
10
18
31
0
0
0
0
24
0
0
0
0
3
10
0
0
Total ......................................................................................................................
45
41
8
3
3
Pacific Creek ................................................................................................................
Jackknife Creek ...........................................................................................................
Trapper Creek ..............................................................................................................
Beaverdam Creek ........................................................................................................
Trout Creek ..................................................................................................................
0
1
12
19
41
4
5
5
8
8
0
0
1
1
0
48
94
82
72
51
48
0
0
0
0
Total ......................................................................................................................
9
5
<1
71
15
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TABLE 8—LAND OWNERSHIP BY PERCENT OF SUBWATERSHEDS (12-DIGIT HUC) WITH NORTHERN LEATHERSIDE CHUB
POPULATIONS—Continued
Upland watershed land ownership by entity
(% land owned)
Population name
BLM
Private
State
USFS
NPS
Green River Subregion
North Fork Slate Creek ................................................................................................
Upper Hams Fork ........................................................................................................
88
12
9
13
3
2
0
73
0
0
Total ......................................................................................................................
30
13
2
55
0
TABLE 9—ESTIMATED LAND OWNERSHIP IN MILES FOR OCCUPIED HABITAT OF NORTHERN LEATHERSIDE CHUB
POPULATIONS
Land ownership of occupied
habitat
BLM
(percent)
Private
(percent)
State
(percent)
USFS
(percent)
NPS
(percent)
Approximate
river miles of
occupied habitat
0
0
2
40
30
65
5
100
100
96
40
70
35
0
0
0
2
20
0
0
95
0
0
0
0
0
0
0
0
0
0
0
0
0
0
10
15
27
9
3
3
5
0
0
15
20
10
0
0
60
50
90
0
0
0
0
0
0
100
25
30
0
100
0
0
0
0
2
8
8
3
5
North Fork Slate Creek ....................................................................
Upper Hams Fork ............................................................................
80
10
20
15
0
15
0
60
0
0
9
10
Total Estimated River Miles ......................................................
................
................
................
................
................
117
Population name
Bear River Drainage
Upper Mill/Deadman Creeks ............................................................
Upper Sulphur/La Chapelle Creeks .................................................
Yellow Creek ....................................................................................
Upper Twin Creek ............................................................................
Rock Creek ......................................................................................
Dry Fork Smiths Fork .......................................................................
Muddy Creek ....................................................................................
Snake River Drainage
Pacific Creek ....................................................................................
Jackknife Creek ...............................................................................
Trapper Creek ..................................................................................
Beaverdam Creek ............................................................................
Trout Creek ......................................................................................
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Green River Drainage
Quantifying riparian habitat
ownership for areas surrounding
occupied northern leatherside chub
stream reaches required an internal
investigation. No published information
is available regarding the number of
river-kilometers occupied by northern
leatherside chub populations; therefore,
we calculated a basic estimate by using
presence and absence data supplied by
various researchers and agencies. Our
estimate indicates that occupied riverkilometers for northern leatherside chub
are approximately 188 km (117 mi).
This total includes approximately 115
km (72 mi) on private land in Idaho,
Nevada, Utah, and Wyoming; 29 km (18
mi) on lands managed by the BLM; 14
km (9 mi) on lands managed by the
States of Wyoming and Idaho; and 3 km
(2 mi) and 27 km (17 mi) on lands
managed by the NPS and USFS,
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respectively (Table 9). Thus, a total of
61 percent of the estimated occupied
northern leatherside chub habitat in the
4–State area occurs on privately owned
land (Service 2011, pp. 11–17).
Subwatersheds with significant
portions of federally owned land allow
for greater regulatory control over land
management practices (oil and gas
development, grazing, water
development, mining, etc.) that have the
potential to negatively affect northern
leatherside chub populations and their
habitat. Federal agencies conduct land
management activities under various
legislations (see Federal Mechanisms
below) that do not apply to private
lands. On private lands, the Clean Water
Act (CWA; 33 U.S.C. 1251 et seq.) and
State mechanisms (see below) are the
primary regulatory mechanisms that
regulate land use activities.
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State Mechanisms
Collection or Possession
Northern leatherside chub are
considered ‘‘prohibited’’ species under
the Utah Collection Importation and
Possession of Zoological Animals Rule
(R–657–3–1), making them unlawful to
collect or possess (UAC 2011, pp. 18–
19). These species receive protection
from unauthorized collection and take.
In Wyoming, the use of live baitfish is
prohibited throughout the range of
northern leatherside chub and very few
live baitfish collection licenses are sold
in the Bear River drainage. Persons that
have these permits collect baitfish on a
small scale for individual use (Miller et
al. 2009, pp. 3–4) (see discussion under
Factor B). The State of Idaho has
classified northern leatherside chub as a
‘‘Protected Nongame’’ species, and State
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regulations specify that no person shall
take or possess such species at any time
or in any manner except as provided for
in authorized circumstances (Schriever
2009, p. 1). Northern leatherside chub
are not listed as a protected species in
the State of Nevada; however, the use of
live baitfish is prohibited in the State
within the species’ range, and the
NDOW monitors collection of rare
species by researchers (UDWR 2009, pp.
32–33). These policies are adequately
protecting northern leatherside chub
from overutilization (see Factor B
discussion) and are not expected to
change in the future.
Conservation and Protection
The States of Idaho, Wyoming,
Nevada, and Utah provide protection
and conservation direction for northern
leatherside chub under their State
comprehensive wildlife conservation
strategies, which are required by the
Service for a State wildlife agency to
receive State wildlife grants. In
addition, all States within the range of
the species are signatory to the
‘‘Rangewide Conservation Agreement
and Strategy for Northern Leatherside’’.
The goals of this document are to ensure
the long-term persistence of the
northern leatherside chub within its
historical range and to support the
development of multi-State
conservation efforts through
coordinated conservation actions and
regulatory consistency. The objectives of
the document are to identify and reduce
threats to northern leatherside chub and
its habitat, determine the existing range
of the species, maintain and monitor
existing self-sustaining populations and
their habitat, restore populations at
selected localities within the historical
range, augment selected populations if
necessary, maintain genetic diversity,
and pursue additional research
questions (UDWR 2009, p. 1). Other
signatories to the document include the
Service, BLM, NPS, Bureau of
Reclamation, USFS, Trout Unlimited,
and The Nature Conservancy (UDWR
2009, pp. 2–3). While we do not rely on
these strategies for our finding, they are
extremely valuable because they help
prioritize conservation actions within
each State and form partnerships across
the species’ range (UDWR 2009, entire).
These policies are not expected to
change in the future.
Fish Stocking
The UDWR follows their Policy for
Fish Stocking and Transfer Procedures,
and no longer stocks nonnative fish into
northern leatherside chub habitat
(UDWR 2009, p. 32). This Statewide
policy specifies protocols for the
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introduction of nonnative species into
Utah waters and states that all stocking
actions must be consistent with ongoing
recovery and conservation actions for
State of Utah sensitive species,
including northern leatherside chub.
The Nevada Board of Wildlife
Commissioners has enacted
Commission Policy Number 33, which
states that waters or reaches of waters
managed as ‘‘wild’’ or ‘‘native’’ will not
be stocked with hatchery trout (State of
Nevada Board of Wildlife
Commissioners 1999, p. 5). This
includes northern leatherside chub
waters; therefore, no stocking is done
within the range of the species in
Nevada (Johnson 2011b, pers. comm.).
In Wyoming, northern leatherside chub
waters were historically stocked. There
is now better awareness of northern
leatherside chub-occupied habitat, and
the State generally does not stock in
these waters (Miller 2011, pers. comm.).
The State of Idaho operates similar to
Wyoming, and there is an informal
policy that discourages stocking of
salmonids in northern leatherside chub
habitat (Grunder 2011, pers. comm.).
Although we did not rely on these
policies for our finding, the
implementation of such policies affords
adequate protection to northern
leatherside chub. These policies are not
expected to change in the future.
Water Rights
To a considerable extent, water rights
are managed under State law in the four
States with northern leatherside chuboccupied habitat. The doctrine of prior
appropriation or ‘‘first in time—first in
right’’ is the basis for administering
surface water rights, and each State does
so via a State agency, a State Engineer,
or some combination of the two (BLM
2001, entire). As discussed under Factor
A (Water Development), much of the
northern leatherside chub-occupied
habitat was historically impacted by
surface water development and
diversion. Currently, occupied
subwatersheds in Utah and Idaho are
closed to new water appropriations for
any significant consumptive use such as
large-scale irrigation (Dean 2011, pers.
comm.; Jordan 2011, pers. comm.).
However, subwatersheds occupied by
northern leatherside chub in Nevada
and Wyoming are still open to new
water appropriations (Randall 2011,
pers. comm.; Jacobs and Brosz 2000, p.
7). As described under Factor A (Water
Development), this level of water
development is not a significant threat
to extant populations of northern
leatherside chub because populations
are able to reoccupy temporarily
dewatered areas when flows return, and
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because low water conditions do not
threaten the species because they
evolved to persist in drought conditions.
Future water development in Utah and
Idaho is limited, and limited increases
in surface water usage are predicted for
Nevada (Randall 2011, pers. comm.) and
Wyoming (Schroeder and Hinckley
2007, pp. 6–2 to 6–4) within the range
of the species, indicating that water
development in these States is not a
significant threat, nor is it likely to
become so. Available information
indicates that the State regulatory
mechanisms in existence adequately
protect the northern leatherside chub
from the threat of reduction of habitat
due to water development projects.
Federal Mechanisms
The major Federal mechanisms for
protection of northern leatherside chub
and its habitat are through the CWA
section 404 permitting process, the
CWA section 303(d) impaired water
body list, and the National
Environmental Policy Act (42 U.S.C.
4231 et seq.) (NEPA). Various Executive
Orders (11990 for wetlands, 11988 for
floodplains, and 13112 for invasive
species) provide guidance and
incentives for Federal land management
agencies to manage for habitat
characteristics essential for
conservation. As explained below,
Federal land management agencies
(BLM, USFS, and NPS) have legislation
that specifies how their lands are
managed for sensitive species.
As stated above in the Land
Management section, approximately
two-thirds of the lands in
subwatersheds with northern
leatherside chub are managed by
Federal land agencies, and
approximately one-third of all occupied
stream miles are on these lands. The
northern leatherside chub is designated
as a sensitive species by the BLM in
Utah, Wyoming, Nevada, and Idaho.
The policy in BLM Manual 6840-Special
Status Species Management states:
‘‘Consistent with the principles of
multiple use and in compliance with
existing laws, the BLM shall designate
sensitive species and implement species
management plans to conserve these
species and their habitats and shall
ensure that discretionary actions
authorized, funded, or carried out by the
BLM would not result in significant
decreases in the overall range-wide
species population and their habitats’’
(BLM 2008, p. 10). BLM land
management practices are intended to
avoid negative effects whenever
possible, while also providing for
multiple-use mandates; therefore,
maintaining or enhancing northern
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leatherside chub habitat is being
considered in conjunction with other
agency priorities. Available information
indicates that BLM management
policies are currently adequately
reducing impacts to northern
leatherside chub on BLM land.
The USFS Sensitive Species Policy in
Forest Manual 2670 outlines procedures
for conserving sensitive species. The
policy applies to projects executed
under the 1982 National Forest
Management Act (NFMA) implementing
regulations. The range of the northern
leatherside chub is within USFS Region
4 (Intermountain Region), where it is
designated a sensitive species by the
USFS (USFS 2010, p. 5), and where the
National Forests have land and resource
management plans developed under
NFMA. The USFS manuals and
handbooks codify the agency’s policy,
practices, and procedures and are
sources of administrative direction for
USFS employees.
The USFS Region 4 applies practices
outlined in their Soil and Water
Conservation Practices Handbook to
northern leatherside chub habitat (USFS
1988, pp. 1–71). This handbook states
that the USFS will apply watershed
conservation practices to sustain
healthy soil, riparian, and aquatic
systems. The handbook provides
management measures with specific
criteria for implementation. For
example, Management Measure No.
11.01 states: ‘‘The Northern and
Intermountain Regions will manage
watersheds to avoid irreversible effects
on the soil resource and to produce
water of quality and quantity sufficient
to maintain beneficial uses in
compliance with State Water Quality
Standards.’’ Irreversible effects include
reduced natural woody debris, excess
sediment production that could reduce
fish habitat, water temperature and
nutrient increases that could affect
beneficial uses, and compacted or
disturbed soils that could cause site
productivity loss and increased soil
erosion. The USFS land management
practices are intended to avoid these
effects whenever possible, while also
providing for multiple-use mandates;
therefore, maintaining or enhancing
northern leatherside chub habitat is
being considered in conjunction with
other agency priorities. Available
information indicates that USFS and
BLM management policies are
adequately reducing impacts to northern
leatherside chub on USFS land.
The National Park Service Organic
Act (16 U.S.C. 1 et seq.) specifies that
the NPS will ‘‘promote and regulate the
use of the Federal areas known as
national parks, monuments, and
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reservations * * * which purpose is to
conserve the scenery and the natural
and historic objects and the wild life
therein and to provide for the enjoyment
of the same in such manner and by such
means as will leave them unimpaired
for the enjoyment of future
generations.’’ Consequently, livestock
grazing, timber harvest, mining, and
water development do not occur in
Grand Teton National Park. The 2006
NPS Management Policies’ section
4.4.1.1 (Plant and Animal Population
Management Principles) states that the
NPS will maintain all native plant and
animal species and their habitats inside
parks. In addition, these policies state
that ‘‘the (National Park) Service will
work with other land managers to
encourage the conservation of the
populations and habitats of these
species outside parks whenever
possible’’ (NPS 2006, p. 43). The
implementation of previously described
policies should afford some protection
to northern leatherside chub. Available
information indicates that NPS statutes,
regulations, and management policies
adequately reduce impacts to the
species.
The NEPA provides authority for the
Service to assume a cooperating agency
role for Federal projects undergoing
evaluation for significant impacts to the
human environment. This includes
participating in updates to resource
management plans. As a cooperating
agency, we have the opportunity to
provide recommendations to the action
agency to avoid impacts or enhance
conservation for northern leatherside
chub and its habitat. For projects where
we are not a cooperating agency, we
often review proposed actions and
provide recommendations to minimize
and mitigate impacts to fish and wildlife
resources. Acceptance of our NEPA
recommendations is at the discretion of
the action agency. The BLM and USFS
land management practices are intended
to ensure avoidance of negative effects
to species whenever possible, while also
providing for multiple-use mandates;
therefore, maintaining or enhancing
northern leatherside chub habitat is
considered in conjunction with other
agency priorities. We determine that
NEPA and its implementing regulations
and policies are currently adequately
reducing impacts to northern
leatherside chub.
The CWA is the primary legislation
protecting water quality in U.S. aquatic
habitats and establishes a process to
identify and clean polluted waters.
Section 303(d) of the CWA requires each
State to develop a list of impaired
waters, defined as a waterbody that does
not meet certain water-quality uses
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(CWA 1977, entire). States must
evaluate all existing and readily
available information in developing
their lists of impaired waters (EPA 2002,
p. 9). There are several established
water quality uses including drinking
water supply, swimming, and aquatic
life support (EPA 2002, p. 11). To meet
the aquatic life support use, a waterbody
must provide suitable habitat for a
balanced community of aquatic
organisms (EPA 2002, p. 11). Best
professional judgment, along with
numeric and narrative criteria created
by the State and the EPA, is considered
when evaluating the ability of a water
body to serve its uses.
Northern leatherside chub population
areas contain wetland and stream
habitats, and section 404 of the CWA
regulates fill in wetlands and streams
that meet certain jurisdictional
requirements. Activities that result in
fill of jurisdictional wetland and stream
habitat require a section 404 permit. We
can review permit applications and
provide recommendations to avoid and
minimize impacts and to implement
conservation measures for fish and
wildlife resources, including the
northern leatherside chub. However,
incorporation of Service
recommendations into section 404
permits is at the discretion of the U.S.
Army Corps of Engineers (Corps). In
addition, not all activities in wetlands
or streams involve fill and not all
wetlands or streams fall under the
jurisdiction of the Corps. Regardless,
earlier in this finding we evaluated
threats to northern leatherside chub
habitat where fill of wetlands or streams
may occur, including mining and oil
and gas development. We found no
information indicating that impacts
from stream or wetland fill are acting on
the species to the point that the species
itself may be at risk, nor is it likely to
become so.
Summary of Factor D
Available information indicates that
land management regulatory
mechanisms are sufficiently minimizing
and mitigating potential threats from
land development to extant northern
leatherside chub populations. The BLM
and USFS continue to work with
permittees on Federal lands to
implement beneficial land use practices
and minimize impacts. The BLM and
USFS have provided protective
mechanisms for conservation agreement
and sensitive species, including the
northern leatherside chub, which can
minimize impacts from oil and gas
drilling, mining, and grazing. We have
the ability to comment on NEPA
evaluations for other projects on BLM
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and USFS lands that may impact the
northern leatherside chub. The NPS
mandate to conserve wildlife and leave
it unimpaired has allowed NPS lands to
currently be adequately and sufficiently
protected and will sufficiently minimize
future threats on NPS-managed lands.
As discussed above, the BLM, USFS,
and NPS are also signatories to the
‘‘Rangewide Conservation Agreement
and Strategy for Northern Leatherside’’,
the goals of which are to ensure the
long-term persistence of the northern
leatherside chub and to support the
development of multi-State
conservation efforts through
coordinated conservation actions and
regulatory consistency. As signatories to
this conservation strategy these agencies
are addressing issues related to the
northern leatherside chub.
Although regulatory mechanisms are
not in place to sufficiently protect the
northern leatherside chub from local or
large-scale water withdrawal and
development in Wyoming and Nevada,
projected development in these States
should be minimal in the areas where
northern leatherside chub occurs (see
Factor A: Water Development for more
information regarding water withdrawal
and development). We found no
information that inadequacy of existing
regulatory mechanisms may act on this
species to the point that the species
itself may be at risk, nor is it likely to
become so.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Natural and manmade threats to
northern leatherside chub include: (1)
Hybridization; (2) climate change; and
(3) cumulative effects of all activities
that may impact the species.
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Hybridization
Hybridization can be a concern for
some fish populations. An introgressed
population can result when a
genetically similar species is introduced
into or invades northern leatherside
chub habitat, the two species interbreed
(i.e., hybridize), and the resulting
hybrids survive and reproduce. If the
hybrids backcross with one or both of
the parental species, genetic
introgression occurs (Schwaner and
Sullivan 2009, p. 198). Continual
introgression can eventually lead to the
loss of genetic identity of one or both
parent species, thus resulting in a
‘‘hybrid swarm’’ consisting entirely of
individual fish that often contain
variable proportions of genetic material
from both of the parental species (Miller
and Behnke 1985, p. 514).
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Hybridization is commonly associated
with disturbed environments (Helfman
2007, p. 215) because in natural,
complex habitats, different species are
able to reproduce separately by using
different habitat types. Additionally,
disturbances allow dispersal of species
to habitats where they did not naturally
occur. For example, water diversions
and transfers may allow isolated habitat
that previously held distinctly separate
populations (allopatric) to overlap
habitats (sympatric) and present an
opportunity for hybridization to occur.
We are aware of a historical record
that fish collections from Sulphur Creek
in the Bear River subregion contained
redside shiner x leatherside chub
hybrids and that it is possible for
leatherside chub to hybridize with
speckled dace (Baxter and Stone 1995,
pp. 70–71); however, we do not know
how this determination was made (i.e.,
morphologically or via genetic analysis),
or when these fish were collected.
Northern leatherside chub populations
coexist with speckled dace in La
Chapelle, Mill, Sulphur, and Yellow
Creeks, where both species are native to
these drainages (Amadio et al. 2009, p.
1). Examination of northern leatherside
chub from these drainages using
morphological characteristics suggested
that populations in La Chapelle Creek
and Yellow Creek were genetically pure,
but that specimens from the other two
creeks exhibited intermediate
morphological characteristics of both
species, thereby suggesting potential
hybridization. However, subsequent
genetic analysis determined that there
was no evidence of genetic mixing; thus
we conclude that hybridization is not
occurring in these drainages at
significant levels (Amadio et al. 2009,
entire). Although no other
hybridization-specific studies were
conducted on northern leatherside
chub, other recent genetic investigations
have not documented hybridization in
extant northern leatherside chub
populations (Johnson and Jordan 2000,
entire; Johnson et al. 2004, entire).
In summary, recent examination of
northern leatherside chub from habitats
where potential northern leatherside
chub hybrids were historically found
has determined that hybridization is not
present. Genetically pure northern
leatherside chub still occur at these
sites, and no new evidence of
hybridization has surfaced. Despite the
historical supposition of hybridization
in some localized areas, there are no
known new occurrences. We found no
information that hybridization may act
on this species to the point that the
species itself may be at risk, nor is it
likely to become so.
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63469
Climate Change
Stream conditions across the range of
the northern leatherside chub are
shaped by regional climatic conditions,
primarily precipitation and temperature.
Water and precipitation is limited in
this arid region. Seasonally, conditions
range from cold, snowy winters to hot,
dry summers. Annually, extended
oscillations between wet and dry
periods also are common (Barnett et al.
2008, p. 1080). Hydrological patterns are
dominated by high-elevation snow
accumulation that subsequently
supports spring runoff and groundwater
recharge (Haak et al. 2010, p. 1).
Northern leatherside chub evolved in
this arid ecosystem, demonstrating their
ability to withstand historical climatic
variability, including drought
conditions.
Predictions of future climatic
conditions can no longer rely on
analysis of past climatic trends, but
must instead take into account
predicted global climate change. Both
the Intergovernmental Panel on Climate
Change and the U.S. Global Climate
Change Program conclude that changes
to climatic conditions, such as
temperature and precipitation regimes,
are occurring and are expected to
continue in western North America over
the next 100 years (Parson et al. 2000,
p. 248; Smith et al. 2000, p. 220;
Solomon et al. 2007, p. 70, Table TS.76;
Trenberth et al. 2007, pp. 252–253, 262–
263). Climate variability adds
uncertainty to predictions of water
availability in stream systems, both in
volume of water and timing of flows
(Haak et al. 2010, p. 2). Therefore, it is
important to consider how future
climatic conditions may impact
northern leatherside chub.
In western North America, surface
warming and precipitation changes
resulting in reduced mountain
snowpack (Trenberth et al. 2007, p. 310;
Mote et al. 2005 and Regonda et al.
2005, cited in Vicuna and Dracup 2007,
p. 330) and a trend toward earlier
snowmelt (Stewart et al. 2004, pp. 217,
219, 223) are climatic conditions most
likely to impact stream ecosystems
(Field et al. 2007, p. 619; EPA 2008, p.
11; American Fisheries Society 2010, p.
7). Less snow accumulation, along with
earlier and more rapid snowmelt, can
affect physical ecosystem properties in
many ways, such as: Reducing aquifer
recharge and groundwater supplies for
consistent stream flows; increased water
temperatures associated with lower
summer stream flows; increased spring
flooding from rain storms onto
snowpack; increased wildfire risk from
earlier snowmelt and drier vegetation;
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and prolonged drought conditions
(American Fisheries Society 2010, p. 11;
many citations in Haak et al. 2010, p. 2).
The alterations, especially reduction in
consistent flows and increased water
temperatures, also will have a myriad of
biotic ecosystem effects, including:
Reduction in available aquatic habitat
and resources (increasing competition,
while simultaneously reducing carrying
capacity); alteration of migration and
reproduction patterns; shifting species
assemblages as suitable conditions move
geographically; and increased nonnative
species invasions (Helfman 2007, pp.
185–186; American Fisheries Society
2010, p. 11). Out of this large set of
impacts, we will analyze the following
potential impacts of climate change on
northern leatherside chub because they
are the most likely to negatively impact
the species: Increased chance of extreme
events (spring floods, severe wildfire,
and prolonged drought); shift in
distribution to higher elevation or
latitude; and upstream shift of
nonnative trout.
Increased Chance of Extreme Events
The first potential impact from
climate change is increased likelihood
of extreme events, such as spring floods,
wildfire, and drought. Because northern
leatherside chub populations mostly
occur in small, localized areas and in
smaller streams, a localized extreme
event that alters stream conditions to
lethal levels could extirpate a local
population isolated or fragmented from
other populations. Furthermore, isolated
populations are at a greater risk of
extirpation because recolonization
following the event may be precluded
(American Fisheries Society 2010, p. 9).
The three most likely extreme events
that would affect northern leatherside
chub are atypical spring floods, severe
wildfire, and prolonged drought.
Northern leatherside chub seemingly
have a tolerance of short-term, extreme
environmental conditions (Belk and
Johnson 2007, pp. 70–71), suggesting
the species may be able to adapt to
short-term disturbances resulting from
climate change.
Uncharacteristic flooding may be a
large stressor for fish species (Williams
et al. 2009, p. 533; American Fisheries
Society 2010, p. 7), especially smallbodied individuals (Harvey 1987, p.
851) like the northern leatherside chub.
A flood event could wash individuals
from local habitats, carrying them
downstream to unsuitable habitats, such
as reservoirs, mainstem channels, or
even onto upland habitat, or could
cause direct mortality (Poff 2002, p.
1500). Even if individuals survived,
they may not be able to return to their
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native location if they were carried over
fish barriers. As an example of this for
closely related minnow species,
biologists hypothesize that a monsoonal
flood event in Clay Creek, a tributary to
the East Fork of the Sevier River, may
be responsible for the extirpation of
aquatic populations, including the
southern leatherside chub (Golden et al.
2009, p. 2; Borden and Cox 2010, p. 2).
The likelihood of entrainment during
flood conditions is reduced because
canals carry less percentage of the river
into the canal and during high flows,
most canals are closed to preserve
infrastructure and fields likely have
enough water.
All species of native fish could be
impacted by wildfire effects, elevating
the topic to a primary concern for
western forest ecosystem management
(Rinne 2004, p. 151). Severe wildfires
(complete denuding of landscape and
death of all vegetation) can alter stream
systems both instantaneously (ash
inputs changing water chemistry or
flames heating stream water) and
chronically (debris and sediment inputs
from denuded uplands, or water
warming from lack of riparian
vegetation) (multiple citations in
American Fisheries Society 2010, p. 9).
These changes cannot only cause fish
mortality and population loss, but also
have long-term effects on the food web
through macroinvertebrate mortality
(Rinne 1996, p. 653). Severe wildfire
events have caused documented local
extirpation events for multiple salmonid
populations in the western United
States (Rinne 1996, p. 653; 2004, p.
151), but in areas where nearby source
populations exist, recolonization has
occurred (Howell 2006, p. 983). We
expect similar responses from northern
leatherside chub because severe
wildfires often produce conditions that
are more extreme than the occupied
habitats discussed in previous sections,
such as under Factor A: Grazing.
Additional impacts arise from fire
suppression efforts that can create
physical disturbances (increased erosion
and overland flow, temporary reduction
or cessation of flows in small streams
when drafting or dipping water (Backer
et al. 2004, p. 939, Table 1), or chemical
disturbances (commonly used fire
retardants and suppressant foams are
toxic to aquatic species)) (Gaikowski et
al. 1996, p. 252; Buhl and Hamilton
2000, p. 408; McDonald et al. 1996, p.
63). It is possible that a severe wildfire
could threaten northern leatherside
chub through both immediate and longterm effects.
Northern leatherside chub are
resilient to moderate wildfire conditions
(charred landscape but some vegetation
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remains). For example, a 1991 fire
centered in the Trail Creek portion of
the Jackknife Creek subwatershed
(Snake River subregion) did not
extirpate the population (Isaak and
Hubert 2001, p. 27). Five years after the
fire, individuals were found in multiple
locations throughout the Jackknife Creek
subwatershed, indicating population
persistence (Isaak and Hubert 2001, pp.
26–27). It is worth noting that the entire
subwatershed was not burned and that
individuals caught in 1996 may be
emigrants from a nearby population
from the tributary Squaw Creek.
Regardless, northern leatherside chub
were found to be persisting in the still
degraded post-fire Trail Creek area, with
stream temperatures often exceeding
23 °C (73 °F) in the summer because of
a lack of riparian cover (Isaak and
Hubert 2001, p. 27).
Prolonged drought is the third
category of extreme event we considered
as a potential threat to northern
leatherside chub. Prolonged drought
alters stream conditions by reducing
available water, leading to diminished
habitat and habitat of lower quality (e.g.,
increased temperature, decreased
oxygen) (Helfman 2007, p. 184). The
presence of suitable water conditions in
streams is fundamentally linked to the
distribution, reproduction, fitness, and
survival of fish species (Helfman 2007,
p. 97; American Fisheries Society 2010,
p. 7). Less available habitat space causes
niches to overlap, increasing predatory
pressure on prey species and
competitive pressures throughout the
food web, and causing an overall
reduction in carrying capacity and
supported biomass (Helfman 2007, p.
13). Northern leatherside chub diets
overlap with many other native fish
species (Bell and Belk 2004, p. 414), and
they are a prey species for others,
demonstrating that these biotic effects
could potentially arise.
Prolonged drought also has a human
component, as drought conditions
generally lead to increased irrigation
demands on stream and groundwater
resources (Alley et al. 1999, pp. 20–21).
This suggests that human demands
could exacerbate natural drought
conditions created by climate change
(EPA 2008, p. 12). Additionally, within
the Bear River subbasin, irrigation
canals might take larger percentages of
the river flow in low-flow years, which
would likely entrain a correspondingly
higher percentage of fish, including
northern leatherside chub (Gale et al.
2008, p. 1546), but the relationship may
not be one to one (Hanson 2001, p. 331).
All of these disturbance events
currently occur in localized areas across
the species’ range. Nevertheless, future
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climate conditions may increase the
severity or frequency of the events (EPA
2008, p. 11). To test this possibility, the
USGS and Trout Unlimited recently
analyzed how predicted future climatic
conditions would alter the risk of
extreme floods, wildfire, and drought
for all subbasins containing inland
native trout species. With this
information they produced risk
classifications applied at the
subwatershed scale (Haak et al. 2010,
pp. 1–16; Service 2011, pp. 1–4).
Because the risk of these three events
are species-independent (results are
based on climate, elevation, etc., and
not species characteristics), and because
northern leatherside chub distribution
overlaps with Yellowstone, Bonneville,
and Colorado River cutthroat trout, the
risk models created in this report can be
wildfires because they inhabit
elevational bands that are expected to
have earlier snowmelt and subsequent
longer fire seasons, except the Goose
Creek subbasin (Table 10) (Haak et al.
2010, pp. 12, 30, 59; Service 2011, pp.
1–4). However, wildfire effects will
likely be local in scale and we expect
northern leatherside chub can either
retreat to habitat refuges during a fire, or
recolonize extirpated areas after a fire
has ended because most populations
have a recolonization potential. All
populations except for the Pacific Creek
population (moderate risk from higher
elevation and higher mean
precipitation) were at a high risk for
future forecasted drought impacts (Table
10) (Haak et al. 2010, pp. 15, 31, 60;
Service 2011, pp. 1–4).
applied to all extant northern
leatherside chub populations.
Researchers used existing broad-scale
data, combined with local drainage
characteristics, to describe potential
future disturbance regimes (Haak et al.
2010, pp. 5–16). Using their results, we
determined potential risk to northern
leatherside chub populations from these
disturbances. All extant northern
leatherside chub populations had a low
risk of extreme winter flooding except
the three populations in the Goose
Creek subbasin, which had moderate
risk resulting from a future forecasted
transition from snow to snow/rain mix
(Table 10) (Haak et al. 2010, pp. 9, 30,
59; Service 2011, pp. 1–4). Rangewide,
all northern leatherside chub
populations occur in watersheds
assessed at high risk for increased
TABLE 10—RISK ASSESSMENT OF NORTHERN LEATHERSIDE CHUB POPULATIONS [HAAK et al. 2010]
National hydrography dataset
subbasin
Risks classifications from USGS climate change
paper
Population
Flood
Upper Bear ...................................
Central Bear .................................
Snake Headwaters .......................
Salt River ......................................
Goose Creek ................................
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Upper Green River/Slate Creek ...
Blacks Fork ...................................
Upper Mill/Deadman Creeks ...................................
Upper Sulphur/La Chapelle Creeks ........................
Yellow Creek ...........................................................
Upper Twin Creek ...................................................
Rock Creek ..............................................................
Dry Fork Smiths Fork ..............................................
Muddy Creek ...........................................................
Pacific Creek ...........................................................
Jackknife Creek .......................................................
Trapper Creek .........................................................
Beaverdam Creek ....................................................
Trout Creek ..............................................................
North Fork Slate Creek ...........................................
Upper Hams Fork ....................................................
This analysis demonstrates that most
subwatersheds harboring northern
leatherside chub (11 of 14) are at risk for
increased wildfire impacts. Even more
strikingly, all extant northern
leatherside chub populations are at risk
for increased drought conditions
because local conditions will not
mitigate predicted regional extreme
drought. However, most northern
leatherside chub populations (11 of 14)
are not at risk for increased flooding
caused by earlier rain on snow events.
Based on this analysis we conclude
that enhanced spring flooding is not a
threat to populations of northern
leatherside chub because only a fraction
of the populations are at risk from this
factor. Northern leatherside chub
populations assessed at moderate to
moderate/high risk of spring flooding
occur in the Goose Creek subbasin,
Snake River subregion. Spring flooding
could be a factor or become a threat
depending upon the magnitude of the
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Wildfire
Drought
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Moderate ..........
Moderate/High ..
Moderate/High ..
Low ...................
Low ...................
High ..................
High ..................
High ..................
High ..................
High ..................
High ..................
High ..................
High ..................
High ..................
Low ...................
Low ...................
Low ...................
High ..................
High ..................
High.
High.
High.
High.
High.
High/Moderate.
High.
Moderate.
High.
High.
High.
High.
High.
High/Moderate.
flooding event, which could displace
fish downstream into reservoir habitats
where predation is a concern or strand
individuals into unsuitable habitats or
out of the water channel.
Although there is evidence that
wildfire risks will increase, we conclude
that wildfire also is not a substantial
risk to the entire species, because
wildfires and wildfire effects will likely
be local in scale relative to the large,
multi-state, widely distributed range of
the species. Local wildfires may
extirpate populations, but we expect
northern leatherside chub can either
retreat to habitat refuges during a fire, or
recolonize extirpated areas after a fire
has ended because most populations
have a recolonization potential (see
discussion under Factor A:
Fragmentation and isolation section).
We hypothesize that a similar
mechanism took place in Jackknife
Creek in the early 1990s, allowing the
population to persist after a wildfire.
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Increased drought is a predicted
rangewide problem for northern
leatherside chub populations (Table 10).
While this species evolved in an arid
region and dealt with historical drought
conditions, human modifications to
riverine systems for water consumption
(irrigation diversions, reservoir
construction and management,
municipal water use, etc.) have greatly
altered the natural hydrology over the
past 200 years. Therefore, current
conditions, including human water
development, must be analyzed. An
analysis of water development in extant
population locations indicates that
dewatering is not common in most
populations, suggesting that these
populations have elasticity to deal with
lower water availability in the future. In
addition, northern leatherside chub are
documented to persist in degraded
habitats, such as remnant pools, and
seem to persist in short-term low water
conditions (Belk and Johnson 2007, p.
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71). Because of these adaptations to deal
with harsh conditions, and their ability
to shift habitats as drought conditions
warrant, drought has a limited effect on
the species rangewide. We found no
information that drought may act on this
species to the point that the species
itself may be at risk, nor is it likely to
become so.
Northern Leatherside Chub and
Nonnative Trout Habitat Shifts
Large-scale climatic warming trends
are expected to result in warmer water
temperatures nationwide (EPA 2008, p.
8). Because water temperature is a
keystone feature of fish community
distribution, predicted changes are
expected to negatively affect cold-water
fisheries continent-wide and cool-water
fisheries in the southern latitudes, while
benefiting warm-water species
continent-wide and cool-water species
in the northern latitudes (Field et al.
2007, p. 631). Northern leatherside chub
are adapted to warmer water
temperatures, including seasonal water
temperature changes associated with
late summer baseflows in mid-elevation
streams (Wilson and Belk 2001, p. 39;
Belk and Johnson 2007, p. 71). As such,
northern leatherside chub may not be as
vulnerable to warming water trends as
cold-water species such as brook trout.
Where suitable upstream habitats are
available and stream gradient permits,
we expect that northern leatherside
chub populations can transition
upstream, tracking suitable habitat
conditions. Across the range of the
species, most extant northern
leatherside chub populations occur in
mid-headwater reaches with upstream
habitat often unoccupied by
individuals. For example, for a few
populations in the Bear River and Green
River subregions, their upstream
distribution is demarcated by the
presence of brook trout or possibly
cooler water temperatures, which are
predicted to shift upstream and decline
as water temperatures warm if
forecasted climate change impacts occur
(Field et al. 2007, p. 624).
If predicted water temperatures
conditions change across the range of
the northern leatherside chub, the
distribution of other fish species will
shift as well, including those that could
impact northern leatherside chub (see
discussion under Factor C: Predation).
Low water temperatures are believed to
currently restrict the distribution of
brown trout (Sigler and Sigler 1996, p.
206), suggesting that region-wide
warming water temperatures may
benefit the species through increasing
suitable upstream habitats. On the other
hand, because rainbow trout are able to
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tolerate more wide-ranging water
temperatures (Sigler and Sigler 1996, p.
184), their distribution may only
moderately change.
Because brown trout are more tolerant
of warmer waters than other trout
species, increased stream temperatures
as a result of climate change effects may
allow brown trout populations to
expand their range upstream and
possibly impact three populations of
northern leatherside chub, two in the
central Bear River subbasin and one in
the Salt River subbasin. For example,
brown trout in lower Jackknife Creek are
currently limited by cooler water
temperatures and may be able to migrate
(shift) upstream if increasing water
temperatures result from climate change
effects, as there are no physical barriers
to movement. Although the Jackknife
Creek leatherside chub population may
be vulnerable to any future brown trout
upstream re-distribution from warming
waters, it is unclear how Jackknife Creek
water temperatures will change, and
how chub and brown trout will respond
in terms of migration into currently
unoccupied upstream and adjacent
tributary habitats. Because northern
leatherside chub currently occur in an
approximately 13-km reach and at least
two adjacent tributaries, it is highly
unlikely that the species would be
eliminated throughout this reach in the
event brown trout redistributed
upstream in response to warming water
temperatures. Northern leatherside chub
populations in the Dry Fork Smiths Fork
or Muddy Creek (Bear River subregion)
are not considered vulnerable to future
impacts from downstream brown trout
populations as a result of climate
change, as existing fish passage barriers
and degraded habitat conditions will
likely inhibit their movement.
We expect that the distribution of
existing rainbow trout populations will
likely remain similar to today, or only
change moderately because they are
thermal generalists. Rainbow trout
overlap with two extant northern
leatherside chub populations, and any
existing impacts are not likely to
increase as a result of climate change.
Brook trout populations will likely be
negatively impacted by climate change
because they are a cold-water fish
(Sigler and Sigler 1996, p. 212). We
expect any future climate change effects
will reduce brook trout abundance
upstream of extant northern leatherside
chub populations (i.e., brook trout
occurrences that are not currently
threatening the northern leatherside
chub), which could benefit northern
leatherside chub that may migrate
upstream into suitable habitats no
longer inhabited by brook trout.
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We found no information that
warming stream temperatures may act
on this species to the point that the
species itself may be at risk, nor is it
likely to become so. Northern
leatherside chub are adapted to warmer
water temperatures, including seasonal
water temperature changes associated
with late summer baseflows in midelevation streams. Most populations
occur in streams with currently
upstream habitats that may become
suitable as stream temperatures change,
allowing populations to shift into
currently unoccupied upstream or
adjacent stream habitats. One northern
leatherside chub population in Jackknife
Creek may become vulnerable to future
brown trout predation if brown trout
redistribute upstream as a result of
warming waters due to climate change,
although it is unclear how Jackknife
Creek water temperatures will change
and how both chub and brown trout
will respond in terms of migration into
currently unoccupied upstream and
adjacent tributary habitats.
Summary of Impacts of Climate Change
Because northern leatherside chub are
able to survive in broad habitat
conditions and tolerate warm water
temperatures (Wilson and Belk 2001;
Nannini and Belk 2006, p. 454), we
believe that populations will be resilient
to small-scale abiotic changes to habitat
because of climate change (upstream
habitat shift caused by temperature
changes, etc.). We also believe there is
adequate upstream habitat to facilitate
upstream migration of populations in
the face of warming stream
temperatures.
Recent modeling efforts predict
increased frequency of catastrophic
events, especially increased wildfires
and prolonged drought. We expect
connected, large populations to weather
these disturbances with natural
demographic fluctuations. Wildfire
impacts will likely take place on a small
enough geographic scale to allow some
portion of northern leatherside
populations to survive, which will
allow for recolonization and population
expansion after the fire has receded and
habitat has recovered. Prolonged or
more frequent drought will likely occur
on a larger scale. However, we expect
northern leatherside chub to persist
during these periods because
individuals can survive in broad habitat
conditions and are tolerant of low water
levels. While the smaller, more isolated
northern leatherside chub populations
are at an increased risk from increased
frequency of possible stochastic events
associated with climate change, there is
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still uncertainty on how, when, or if,
these impacts may occur.
Shifting distributions of nonnative
trout also are not expected to create
undue risk to the species. Only one
population of northern leatherside chub
in Jackknife Creek may be at increased
risk from shifting nonnative trout;
therefore, we believe the species as a
whole is resilient to this threat. We
found no information that climate
change effects may act on this species to
the point that the species itself may be
at risk, nor is it likely to become so.
Cumulative Impacts
Some of the threats discussed in this
finding can work in concert with one
another to cumulatively create
situations that will impact northern
leatherside chub beyond the scope of
each individual threat. For example, as
discussed under Factor C: Predation, the
impacts of nonnative trout are
exacerbated by drought conditions
because individual northern leatherside
chub will be exposed to brown trout if
their side channel habitats are
eliminated. In the absence of drought
conditions, northern leatherside chub
can potentially persist in the presence of
brown trout, albeit in low densities.
Similarly, in the absence of brown trout,
drought conditions are not a threat to
northern leatherside chub because the
species is adapted to withstand a broad
range of habitat conditions including
higher stream temperatures and low
water levels. Because of this
relationship, we will analyze the
cumulative impact of drought (as a
result of climate change), water
development (human-caused water
reduction), and nonnative trout
presence.
We also analyze the relationship
between population size, isolation, and
potential threats. Dense, connected
populations are able to withstand
impacts more vigorously than small,
isolated populations. Dense populations
are able to lose individuals without a
corresponding loss of the entire
population, but small populations are
vulnerable if even a few individuals are
lost. Similarly, connected populations
are more secure from threats because
nearby populations can provide rescue
effects (immigrants and recolonization).
In contrast, isolated populations have
no potential to be rescued, so local
extirpation is likely permanent.
Drought, Water Development, and
Nonnative Trout
As mentioned previously, when
nonnative trout are present, drought
conditions greatly intensify northern
leatherside chub mortality risk. Five
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northern leatherside populations harbor
nearby or resident populations of
rainbow or brown trout (Table 7): Dry
Fork Smiths Fork and Muddy Creeks in
the Bear River subregion; Jackknife and
Trapper Creeks in the Snake River
subregion; and Upper Hams Fork in the
Green River subregion. All five of these
populations have either high or
moderate-to-high risk of increased
drought from climate change (Table 10);
however, none of these five populations
have experienced dewatering events in
the past (Table 5), indicating that
natural flow (not irrigation) conditions
will drive the water supply for habitat.
Increased drought will not increase
the risk of nonnative trout in the Dry
Fork Smiths Fork or Muddy Creek
populations because lower water
conditions will only reduce the chance
of brown trout invasion. As a result of
decreased water supply, Muddy Creek
habitat conditions will become even less
suitable for trout and Dry Fork Smiths
Fork will be even more isolated by
culverts.
We believe that the northern
leatherside chub populations in the
Upper Hams Fork and Trapper Creek
will become more impacted by the
resident rainbow trout in drought
conditions. However, the low density of
rainbow trout and the high density of
northern leatherside chub in the Upper
Hams Fork do not put this population
at risk of extirpation. The Trapper Creek
northern leatherside chub population is
less dense and could experience more of
an impact from rainbow trout predation
in drought conditions than Upper Hams
Fork.
Under drought conditions as a result
of climate change, habitat conditions in
the Jackknife Creek subwatershed may
facilitate upstream movement by brown
trout. Such warming conditions will
initially be within the tolerable range of
northern leatherside chub, but may
expand the availability of brown trout
habitat. However, with the possible
exception of the northern leatherside
chub population in Jackknife Creek, the
species should be resilient to smallscale abiotic changes to habitat because
of climate change (upstream habitat
shift caused by temperature changes,
etc.) and there is likely adequate
upstream and nearby tributary habitats
to adapt to under future drought
conditions.
Drought and Water Quality
Two northern leatherside chub
populations that occur in streams listed
as 303(d) water quality impaired
(Beaverdam and Trapper Creeks) may be
at increased risk due to future drought
severity effects (Table 10). The water
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quality impairments in these streams
that would likely impact northern
leatherside chub (elevated sediment and
phosphorous, and low dissolved
oxygen) would be exacerbated under
lower flow conditions that result from
future drought conditions. However,
because there is no current information
on how impaired water quality may be
impacting existing northern leatherside
chub populations, we cannot predict
how future drought conditions will
effect the species’ habitats or water
quality.
Population Fragmentation and Isolation
in Relation to Other Threats
As demonstrated in the preceding
section, impacts that do not threaten
northern leatherside chub
independently may work together and
have substantial, cumulative impacts. In
this analysis, we will analyze the
cumulative impacts to populations and
the species as a whole, paying particular
attention to population isolation and
fragmentation.
In the preceding analysis, we
determined that 7 of 14 northern
leatherside chub populations were
isolated, and 6 of 14 contained only a
single documented occurrence of the
species (see Factor A discussion and
Table 6). Because 3 populations were
both isolated and contained a single
occurrence, the remaining 11
populations were considered
sufficiently resilient in terms of
population size and distribution
(connected to other occurrences or
populations) and only minimally
impacted from the previously analyzed
threats and, therefore, not at increased
vulnerability from various threat factors
due to isolation and fragmentation.
Summary of Factor E
Recent examination of northern
leatherside chub from habitats where
suspected hybrids were historically
found has determined that hybridization
is not present. Therefore, with no
known instances of hybridization, we
conclude that hybridization is not a
threat to northern leatherside chub.
Projected impacts from future climate
change effects will likely impact all
northern leatherside chub populations
to some degree, although the synergistic
effect of these impacts with identified
and potential threats are uncertain.
Because stable, reproducing northern
leatherside chub populations occur at
many locations where degraded habitat
conditions exist, their continued
persistence and successful reproduction
demonstrates that they have some level
of tolerance for less than optimal
environmental conditions. We found no
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information that other natural or
manmade factors affecting its continued
existence may act on this species to the
point that the species itself may be at
risk, nor is it likely to become so.
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Finding
As required by the Act, we considered
the five factors in assessing whether the
northern leatherside chub (Lepidomeda
copei) is endangered or threatened
throughout all or a significant portion of
its range. We examined the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the northern
leatherside chub. We reviewed the
petition, information available in our
files, other available published and
unpublished information, and we
consulted with recognized northern
leatherside chub experts, other Federal
and State agencies, and university
researchers. We also prepared a white
paper that analyzed specific issues to
the species. In considering what factors
might constitute threats, we must look
beyond the mere exposure of the species
to the factor to determine whether the
species responds to the factor in a way
that causes actual impacts to the
species. If there is exposure to a factor,
but no response, or only a positive
response, that factor is not a threat. If
there is exposure and the species
responds negatively, the factor may be
a threat and we then attempt to
determine how significant a threat it is.
If the threat is significant, it may drive
or contribute to the risk of extinction of
the species such that the species
warrants listing as endangered or
threatened as those terms are defined by
the Act. This does not necessarily
require empirical proof of a threat. The
combination of exposure and some
corroborating evidence of how the
species is likely impacted could suffice.
The mere identification of factors that
could impact a species negatively is not
sufficient to compel a finding that
listing is appropriate; we require
evidence that these factors are operative
threats that act on the species to the
point that the species meets the
definition of endangered or threatened
under the Act.
Northern leatherside chub are a small,
mid-elevation fish endemic to streams
within the Bear River, Upper Green
River, and Upper Snake River Basins.
The range of the northern leatherside
chub has declined over the past 50
years, and there are currently 14 extant
populations spread over the Bear (7),
Snake (5) and Green (2) River
subregions. The species evolved in an
arid ecosystem characterized by extreme
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seasonal and annual changes in physical
conditions.
The most widely distributed,
relatively large populations occur in the
Bear River subregion. Most populations
in the Bear River subregion are largely
free of threats (Upper Mill/Deadman
Creeks), contain multiple populations,
can easily interact (Upper Twin Creek
and Rock Creek), and include relatively
high-density populations (Upper Mill/
Deadman Creeks, Yellow Creek, Dry
Fork Smiths Fork, Muddy Creek, Rock
Creek, and Upper Twin Creek). As a
result, we concluded that the size,
connectedness, and stability of the Bear
River populations are sufficient to
ensure the long-term persistence of the
species as a whole. Although less
monitoring and collection information
is available to characterize northern
leatherside chub populations within the
Snake River subbasin, most extant
populations in the Snake River subbasin
are discontinuous from other
populations and have relatively low
population numbers. Three of five
Snake River populations have one or
more factors affecting each population,
primarily impaired water quality and
nonnative trout. These and other factors
were not considered significant or
imminent. We do not fully understand
how these current or potential threats
are impacting the species, and it is
believed that northern leatherside chub
tolerate some level of degraded or shortterm, extreme conditions. Although the
isolation of some Snake River
populations likely increases their
vulnerability to the effects of identified
threats, these threats do not currently or
in the foreseeable future pose a
substantial risk to species rangewide.
When evaluating the potential impact
to northern leatherside chub and their
habitat from future climate change
effects, it is likely that warming water
temperatures predicted to occur will
likely benefit the species, especially in
those stream systems with currently
unoccupied habitats upstream. The
species is tolerant of short-term extreme
environmental conditions, suggesting
the species may be able to survive some
of the shorter-term disturbances from
climate change. Because of the
uncertainty associated with future
climate change predictions, the
synergistic effect of future climate
change scenarios, with identified or
potential threats on stream systems
where the northern leatherside chub
occurs, are unknown.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats are not
of sufficient imminence, intensity, or
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magnitude to indicate that the northern
leatherside chub is in danger of
extinction (endangered), or likely to
become endangered within the
foreseeable future (threatened),
throughout its range. Therefore, we find
that listing the northern leatherside
chub as an endangered or threatened
species throughout its range is not
warranted at this time.
Significant Portion of the Range
Having determined that the northern
leatherside chub is not endangered or
threatened throughout its range, we
must next consider whether there are
any significant portions of the range
where the northern leatherside chub is
in danger of extinction or is likely to
become endangered in the foreseeable
future.
The Act defines ‘‘endangered species’’
as any species which is ‘‘in danger of
extinction throughout all or a significant
portion of its range,’’ and ‘‘threatened
species’’ as any species which is ‘‘likely
to become an endangered species within
the foreseeable future throughout all or
a significant portion of its range.’’ The
definition of ‘‘species’’ is also relevant
to this discussion. The Act defines
‘‘species’’ as follows: ‘‘The term
‘species’ includes any subspecies of fish
or wildlife or plants, and any distinct
population segment [DPS] of any
species of vertebrate fish or wildlife
which interbreeds when mature.’’ The
phrase ‘‘significant portion of its range’’
(SPR) is not defined by the statute, nor
addressed in our regulations: (1) The
consequences of a determination that a
species is either endangered or likely to
become so throughout a significant
portion of its range, but not throughout
all of its range; or (2) what qualifies a
portion of a range as ‘‘significant.’’
Two recent district court decisions
have addressed whether the SPR
language allows the Service to list or
protect less than all members of a
defined ‘‘species’’: Defenders of Wildlife
v. Salazar, 729 F. Supp. 2d 1207 (D.
Mont. 2010), concerning the Service’s
delisting of the Northern Rocky
Mountain gray wolf (74 FR 15123, April.
2, 2009); and WildEarth Guardians v.
Salazar, 2010 U.S. Dist. LEXIS 105253
(D. Ariz. Sept. 30, 2010), concerning the
Service’s 2008 finding on a petition to
list the Gunnison’s prairie dog (73 FR
6660, February. 5, 2008). The Service
had asserted in both of these
determinations that it had authority, in
effect, to protect only some members of
a ‘‘species,’’ as defined by the Act (i.e.,
species, subspecies, or DPS), under the
Act. Both courts ruled that the
determinations were arbitrary and
capricious on the grounds that this
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approach violated the plain and
unambiguous language of the Act. The
courts concluded that reading the SPR
language to allow protecting only a
portion of a species’ range is
inconsistent with the Act’s definition of
‘‘species.’’ The courts concluded that
once a determination is made that a
species (i.e., species, subspecies, or
DPS) meets the definition of
‘‘endangered species’’ or ‘‘threatened
species,’’ it must be placed on the list
in its entirety and the Act’s protections
applied consistently to all members of
that species (subject to modification of
protections through special rules under
sections 4(d) and 10(j) of the Act).
Consistent with that interpretation,
and for the purposes of this finding, we
interpret the phrase ‘‘significant portion
of its range’’ in the Act’s definitions of
‘‘endangered species’’ and ‘‘threatened
species’’ to provide an independent
basis for listing; thus there are two
situations (or factual bases) under which
a species would qualify for listing: A
species may be endangered or
threatened throughout all of its range; or
a species may be endangered or
threatened in only a significant portion
of its range. If a species is in danger of
extinction throughout an SPR, it, the
species, is an ‘‘endangered species.’’
The same analysis applies to
‘‘threatened species.’’ Based on this
interpretation and supported by existing
case law, the consequence of finding
that a species is endangered or
threatened in only a significant portion
of its range is that the entire species will
be listed as endangered or threatened,
respectively, and the Act’s protections
will be applied across the species’ entire
range.
We conclude, for the purposes of this
finding, that interpreting the SPR phrase
as providing an independent basis for
listing is the best interpretation of the
Act because it is consistent with the
purposes and the plain meaning of the
key definitions of the Act; it does not
conflict with established past agency
practice (i.e., prior to the 2007
Solicitor’s Opinion), as no consistent,
long-term agency practice has been
established; and it is consistent with the
judicial opinions that have most closely
examined this issue. Having concluded
that the phrase ‘‘significant portion of
its range’’ provides an independent
basis for listing and protecting the entire
species, we next turn to the meaning of
‘‘significant’’ to determine the threshold
for when such an independent basis for
listing exists.
Although there are potentially many
ways to determine whether a portion of
a species’ range is ‘‘significant,’’ we
conclude, for the purposes of this
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finding, that the significance of the
portion of the range should be
determined based on its biological
contribution to the conservation of the
species. For this reason, we describe the
threshold for ‘‘significant’’ in terms of
an increase in the risk of extinction for
the species. We conclude that a
biologically based definition of
‘‘significant’’ best conforms to the
purposes of the Act, is consistent with
judicial interpretations, and best
ensures species’ conservation. Thus, for
the purposes of this finding, and as
explained further below, a portion of the
range of a species is ‘‘significant’’ if its
contribution to the viability of the
species is so important that without that
portion, the species would be in danger
of extinction.
We evaluate biological significance
based on the principles of conservation
biology using the concepts of
redundancy, resiliency, and
representation. Resiliency describes the
characteristics of a species and its
habitat that allow it to recover from
periodic disturbance. Redundancy
(having multiple populations
distributed across the landscape) may be
needed to provide a margin of safety for
the species to withstand catastrophic
events. Representation (the range of
variation found in a species) ensures
that the species’ adaptive capabilities
are conserved. Redundancy, resiliency,
and representation are not independent
of each other, and some characteristic of
a species or area may contribute to all
three. For example, distribution across a
wide variety of habitat types is an
indicator of representation, but it may
also indicate a broad geographic
distribution contributing to redundancy
(decreasing the chance that any one
event affects the entire species), and the
likelihood that some habitat types are
less susceptible to certain threats,
contributing to resiliency (the ability of
the species to recover from disturbance).
None of these concepts is intended to be
mutually exclusive, and a portion of a
species’ range may be determined to be
‘‘significant’’ due to its contributions
under any one or more of these
concepts.
For the purposes of this finding, we
determine if a portion’s biological
contribution is so important that the
portion qualifies as ‘‘significant’’ by
asking whether without that portion, the
representation, redundancy, or
resiliency of the species would be so
impaired that the species would have an
increased vulnerability to threats to the
point that the overall species would be
in danger of extinction (i.e., would be
‘‘endangered’’). Conversely, we would
not consider the portion of the range at
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issue to be ‘‘significant’’ if there is
sufficient resiliency, redundancy, and
representation elsewhere in the species’
range that the species would not be in
danger of extinction throughout its
range if the population in that portion
of the range in question became
extirpated (extinct locally).
We recognize that this definition of
‘‘significant’’ (a portion of the range of
a species is ‘‘significant’’ if its
contribution to the viability of the
species is so important that without that
portion, the species would be in danger
of extinction) establishes a threshold
that is relatively high. On the one hand,
given that the consequences of finding
a species to be endangered or threatened
in an SPR would be listing the species
throughout its entire range, it is
important to use a threshold for
‘‘significant’’ that is robust. It would not
be meaningful or appropriate to
establish a very low threshold whereby
a portion of the range can be considered
‘‘significant’’ even if only a negligible
increase in extinction risk would result
from its loss. Because nearly any portion
of a species’ range can be said to
contribute some increment to a species’
viability, use of such a low threshold
would require us to impose restrictions
and expend conservation resources
disproportionately to conservation
benefit: Listing would be rangewide,
even if only a portion of the range of
minor conservation importance to the
species is imperiled. On the other hand,
it would be inappropriate to establish a
threshold for ‘‘significant’’ that is too
high. This would be the case if the
standard were, for example, that a
portion of the range can be considered
‘‘significant’’ only if threats in that
portion result in the entire species’
being currently endangered or
threatened. Such a high bar would not
give the SPR phrase independent
meaning, as the Ninth Circuit held in
Defenders of Wildlife v. Norton, 258
F.3d 1136 (9th Cir. 2001).
The definition of ‘‘significant’’ used in
this finding carefully balances these
concerns. By setting a relatively high
threshold, we minimize the degree to
which restrictions will be imposed or
resources expended that do not
contribute substantially to species
conservation. But we have not set the
threshold so high that the phrase ‘‘in a
significant portion of its range’’ loses
independent meaning. Specifically, we
have not set the threshold as high as it
was under the interpretation presented
by the Service in the Defenders
litigation. Under that interpretation, the
portion of the range would have to be
so important that current imperilment
there would mean that the species
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would be currently imperiled
everywhere. Under the definition of
‘‘significant’’ used in this finding, the
portion of the range need not rise to
such an exceptionally high level of
biological significance. (We recognize
that if the species is imperiled in a
portion that rises to that level of
biological significance, then we should
conclude that the species is in fact
imperiled throughout all of its range,
and that we would not need to rely on
the SPR language for such a listing.)
Rather, under this interpretation we ask
whether the species would be
endangered everywhere without that
portion, i.e., if that portion were
completely extirpated. In other words,
the portion of the range need not be so
important that even the species being in
danger of extinction in that portion
would be sufficient to cause the species
in the remainder of the range to be
endangered; rather, the complete
extirpation (in a hypothetical future) of
the species in that portion would be
required to cause the species in the
remainder of the range to be
endangered.
The range of a species can
theoretically be divided into portions in
an infinite number of ways. However,
there is no purpose to analyzing
portions of the range that have no
reasonable potential to be significant or
to analyzing portions of the range in
which there is no reasonable potential
for the species to be endangered or
threatened. To identify only those
portions that warrant further
consideration, we determine whether
there is substantial information
indicating that: (1) The portions may be
‘‘significant,’’ and (2) the species may be
in danger of extinction there or likely to
become so within the foreseeable future.
Depending on the biology of the species,
its range, and the threats it faces, it
might be more efficient for us to address
the significance question first or the
status question first. Thus, if we
determine that a portion of the range is
not ‘‘significant,’’ we do not need to
determine whether the species is
endangered or threatened there; if we
determine that the species is not
endangered or threatened in a portion of
its range, we do not need to determine
if that portion is ‘‘significant.’’ In
practice, a key part of the determination
that a species is in danger of extinction
in a significant portion of its range is
whether the threats are geographically
concentrated in some way. If the threats
to the species are essentially uniform
throughout its range, no portion is likely
to warrant further consideration.
Moreover, if any concentration of
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threats to the species occurs only in
portions of the species’ range that
clearly would not meet the biologically
based definition of ‘‘significant,’’ such
portions will not warrant further
consideration.
Decisions by the Ninth Circuit Court
of Appeals in Defenders of Wildlife v.
Norton, 258 F.3d 1136 (2001) and
Tucson Herpetological Society v.
Salazar, 566 F.3d 870 (2009) found that
the Act requires the Service, in
determining whether a species is
endangered or threatened throughout a
significant portion of its range, to
consider whether lost historical range of
a species (as opposed to its current
range) constitutes a significant portion
of the range of that species. While this
is not our interpretation of the statute,
we first address the lost historical range
before addressing the current range.
Lost Historical Range
The available literature provides
limited information on the historical
distribution of northern leatherside
chub. The type locality for the northern
leatherside chub was discovered in 1881
from the mainstem Bear River near
Evanston, Wyoming (Jordan and Gilbert
1881 in UDWR 2009, p. 39). The species
is historically documented in portions
of the Bear River and Upper Snake River
subregions (Figure 1; Table 1). These
historical collections demonstrate that
the species existed over a wide
geographic area from Idaho, to
Wyoming, and into Utah.
Specifically, historical records (during
the 1950s, 1960s, and 1970s) document
the existence of individuals from three
subbasins containing four locations that
we consider populations today; one
population in the Snake River subregion
(Pacific Creek) and three populations in
the Bear River subregion (Yellow Creek,
Rock Creek, and Muddy Creek) (McAbee
2011, pp. 10, 19). Northern leatherside
chub were also historically found in
three subbasins that do not contain
extant populations (McAbee 2011, p. 2).
More recent investigations documented
northern leatherside chub at two
subbasins (Salt River and Goose Creek)
within the Snake River subregion, thus
adding four populations (Jackknife
Creek, Trapper Creek, Beaverdam Creek,
and Trout Creek) to the accepted
historical range (McAbee 2011, p. 19).
The best scientific data allow us to
document the historical existence of
northern leatherside chub only at the
subbasin scale. These historical data
have more recently been compared to
current distributional information to
determine the presence of extant
historical populations as explained
above. We conclude that the historical
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range of northern leatherside chub
included the following subbasins:
Upper Bear River, Central Bear River,
Logan River, Lower Bear River, Snake
Headwaters, Salt River, Goose Creek,
and Little Wood River.
Over the past 50 years, the range of
the northern leatherside chub has
declined, and the current range of the
species is now contained in five of the
eight documented historical subbasins
(Wilson and Belk 2001, p. 36; Johnson
et al. 2004, pp. 841–842; UDWR 2009,
p. 24). Northern leatherside chub are
likely extirpated from the Little Wood
River in Idaho, where verified museum
records exist, but recent collections
failed to document any extant
populations. Similarly, northern
leatherside chub are likely extirpated
from the Logan and Lower Bear Rivers
in Utah and Idaho, where recent
collections failed to document extant
populations, and past collection
records, while accepted as true, cannot
be verified (McKay 2011, pers. comm.).
Although we acknowledge that there
is some ambiguity in the historical and
current ranges of northern leatherside
chub (see Background: Distribution), we
conclude that the species is extirpated
from three of the eight historically
occupied subbasins: The Logan River,
Lower Bear River, and Little Wood River
subbasins.
As described earlier (see Background:
Distribution), despite the loss of the
three historical populations, there
remain 14 northern leatherside
populations distributed across the Bear
River, Upper Snake River, and Upper
Green River subregions (see Figure 1).
We now consider if the loss of the three
historical populations (Logan River,
Lower Bear River, and Little Wood
River) is so important that individually
or collectively this loss of range
qualifies as ‘‘significant’’ by asking
whether without these portions, the
representation, redundancy, or
resiliency of the species is so impaired
that the species has an increased
vulnerability to threats to the point that
the overall species is in danger of
extinction (see below for more
information on justification for this
assessment).
Although each of the three lost
northern leatherside chub subbasins
discussed above likely has features that
make it unique, we determine that the
historical populations were similar
geographically and biologically to the
current species’ locations. For example,
the species’ potential spawning, feeding,
and sheltering habitat in these locations
was likely similar to current population
locations (see Background: Life History,
Habitat), and all occurred within
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subregions that are currently occupied
(see Figure 1).
The loss of the three historically
occupied subbasins in portions of the
species’ range likely resulted in a
reduction in the species overall
population, but the remaining
populations are independent of these
populations and do not rely on any of
the lost population’s habitat for lifehistory processes (e.g., spawning,
feeding, sheltering). Furthermore, this
potential reduction of reproductive
output has not reduced the species’
range of variation or adaptive
capabilities to such a level that they
would be in danger of extinction.
Despite the loss of these three
historically occupied subbasins, the
resiliency of northern leatherside chub
has not been appreciably impacted, and
the species will continue to be able to
recover from periodic disturbance and
withstand catastrophic events in other
parts of its range.
In summary, although the species is
extirpated from three historically
occupied subbasins, the species is found
in five other historically occupied
subbasins and two additional subbasins
in the Upper Green River subregion and
now comprises 14 populations in these
subbasins. We conclude that these
remaining 14 populations provide
sufficient representation and
redundancy of northern leatherside
chub habitat throughout the species’
current range such that northern
leatherside chub is not in danger of
extinction despite the loss of historical
habitat. Thus, the lost historical range of
northern leatherside chub does not
constitute a significant portion of the
range of the subspecies.
Current Range
After reviewing the potential threats
throughout the range of northern
leatherside chub, we determine that five
of fourteen populations within the
species’ current range could be
considered to have concentrated threats
(see discussion under Factor A, Factor
C, and Factor E). Below, we outline the
elevated risk from potential threats
found at the five populations and then
assess whether these portions of the
species’ range may meet the definition
of ‘‘significant,’’ that is, whether the
contributions of these portions of the
northern leatherside chub’s range to the
viability of the species is so important
that without those portions, the species
would be in danger of extinction.
The Dry Fork Smiths Fork population
(Central Bear River subbasin) is isolated
and likely contains only one occurrence
of northern leatherside chub, making it
vulnerable to a large-scale disturbance
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or stochastic event such as drought. The
Pacific Creek population (Snake
Headwaters subbasin) is similarly
isolated (see discussion under Factor A:
Fragmentation and Isolation of Existing
Populations). In Jackknife Creek (Salt
River subbasin), a brown trout
population occurs downstream of the
northern leatherside chub population
(see discussion under Factor C:
Predation). Although this population
currently coexists with brown trout,
there is the potential that a climate
change-induced increase in water
temperature could force a habitat shift,
pushing predacious brown trout into
core northern leatherside chub habitat
(see discussion under Factor E: Climate
Change). The Beaverdam Creek and
Trapper Creek populations (Goose Creek
subbasin) both occur in streams listed as
303(d) water quality impaired, although
aquatic communities continue to persist
(see discussion under Factor A: Water
Quality). These populations could be at
increased risk if future drought
conditions occur (see discussion under
Factor E: Drought and Water Quality).
The Trapper Creek population co-occurs
with rainbow trout and may be
vulnerable to predation from this
nonnative species (see discussion under
Factor C: Predation and Table 7). Also,
this population is isolated, making it
vulnerable to a large-scale disturbance
or stochastic event such as drought (see
discussion under Factor A:
Fragmentation and Isolation of Existing
Populations and Table 6).
Because the northern leatherside chub
faces elevated risk from potential threats
at the five population locations
discussed above, we next assess
whether these portions of the species’
range may meet the biologically based
definition of ‘‘significant.’’ For these
areas, we evaluate whether the
populations’ biological contributions are
so important that individually or
collectively this hypothetical loss of
range would qualify as ‘‘significant’’ by
asking whether without that portion, the
representation, redundancy, or
resiliency of the species would be so
impaired that the species would have an
increased vulnerability to threats to the
point that the overall species would be
in danger of extinction.
Although each of the five northern
leatherside chub population locations
discussed above likely has features that
make it unique, we determine that they
are similar geographically and
biologically to other species’ locations.
For example, the species’ spawning,
feeding, and sheltering habitat is
essentially the same at all population
locations (see Background: Life History,
Habitat). If the Dry Fork Smiths Fork,
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Pacific Creek, Jackknife Creek, Trapper
Creek, and Beaverdam Creek
populations could no longer support
northern leatherside chub, other
existing population locations could
support the species’ persistence. The
remaining nine population locations are
distributed within the species’ current
and historical range in the Bear River,
Upper Snake River, and Upper Green
River subregions (see Figure 1), and
offer sufficient representation and
redundancy of habitat and range such
that northern leatherside chub would
not be in danger of extinction if these
five population locations were
completely lost.
The loss of these five populations in
portions of the species’ range would
directly result in a reduction in the
species’ overall population size, but the
loss of individual populations would
not cause a reduction in the local
population size of any remaining
population because each northern
leatherside chub population is
independent and does not rely on other
population’s habitat for life-history
processes (e.g., spawning, feeding,
sheltering). Also, the loss of the five
populations would not reduce the
species’ range of variation or adaptive
capabilities to such a level that they
would be in danger of extinction.
Without these five population locations,
we expect that the resiliency of northern
leatherside chub would not be
appreciably impacted; the species
would continue to be able to recover
from periodic disturbances and
withstand catastrophic events in other
parts of its range.
In summary, despite having some
locations of elevated risk to potential
threats, we conclude that the portions of
the northern leatherside chub’s range
where these threats occur are not
significant portions of its range. Even if
all of these population locations were
extirpated at some time in the future,
northern leatherside chub would persist
at population locations not affected by
these threats. As noted above, there is
little that biologically distinguishes Dry
Fork Smiths Fork, Pacific Creek,
Jackknife Creek, Trapper Creek, and
Beaverdam Creek from other population
locations for northern leatherside chub.
The existing, remaining population
locations are distributed across the
species’ historical range in the Bear
River, Upper Snake River, and Upper
Green River subregions and provide
adequate redundancy, resiliency, and
representation for the species.
Therefore, the five population locations
(whether considered separately or
combined) are not a ‘‘significant’’
portion of the species’ range because
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their contribution to the viability of the
species is not so important that the
species would be in danger of extinction
without those portions.
We find that northern leatherside
chub is not in danger of extinction now,
nor is it likely to become endangered
within the foreseeable future throughout
all or a significant portion of its range.
Therefore, listing northern leatherside
chub as endangered or threatened under
the Act is not warranted at this time.
We request that you submit any new
information concerning the status of, or
threats to, northern leatherside chub to
our Utah Ecological Services Field
VerDate Mar<15>2010
19:12 Oct 11, 2011
Jkt 226001
Office (see ADDRESSES section)
whenever it becomes available. New
information will help us monitor
northern leatherside chub and
encourage its conservation. If an
emergency situation develops for the
northern leatherside chub or any other
species, we will act to provide
immediate protection.
References Cited
A complete list of references cited is
available on the Internet at https://
www.regulations.gov and upon request
from the Utah Ecological Services Field
Office (see ADDRESSES section).
PO 00000
Frm 00036
Fmt 4701
Sfmt 9990
Authors
The primary authors of this notice are
the staff members of the Utah and Idaho
Ecological Services Field Offices.
Authority
The authority for this action is section
4 of the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et
seq.).
Dated: September 27, 2011.
Rowan Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2011–25810 Filed 10–11–11; 8:45 am]
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[Federal Register Volume 76, Number 197 (Wednesday, October 12, 2011)]
[Proposed Rules]
[Pages 63444-63478]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-25810]
[[Page 63443]]
Vol. 76
Wednesday,
No. 197
October 12, 2011
Part IV
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; 12-Month Finding on a
Petition To List Northern Leatherside Chub as Endangered or Threatened;
Proposed Rule
Federal Register / Vol. 76 , No. 197 / Wednesday, October 12, 2011 /
Proposed Rules
[[Page 63444]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2011-0092; MO 92210-0-0008-B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List Northern Leatherside Chub as Endangered or
Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list the northern leatherside chub
(Lepidomeda copei) as endangered or threatened and to designate
critical habitat under the Endangered Species Act of 1973, as amended
(Act). After review of all available scientific and commercial
information, we find that listing the northern leatherside chub
rangewide is not warranted at this time. We ask the public to submit to
us any new information that becomes available concerning the threats to
the northern leatherside chub or its habitat at any time.
DATES: The finding announced in this document was made on October 12,
2011.
ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket Number FWS-R6-ES-2011-0092. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, Utah Ecological Services Field Office, 2369
West Orton Circle, Suite 50, West Valley City, UT 84119. Please submit
any new information, materials, comments, or questions concerning this
finding to the above street address.
FOR FURTHER INFORMATION CONTACT: Larry Crist, Field Supervisor, Utah
Ecological Services Field Office (see ADDRESSES); by telephone at 801-
975-3330; or by facsimile at 801-975-3331; or Brian Kelly, Field
Supervisor, Idaho Ecological Services Field Office; by telephone at
208-378-5243; or by facsimile at 208-378-5262. If you use a
telecommunications device for the deaf (TDD), please call the Federal
Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Endangered and
Threatened Wildlife and Plants that contains substantial scientific or
commercial information that listing the species may be warranted, we
make a finding within 12 months of the date of receipt of the petition.
In this finding, we will determine that the petitioned action is: (1)
Not warranted; (2) warranted; or (3) warranted, but the immediate
proposal of a regulation implementing the petitioned action is
precluded by other pending proposals to determine whether species are
endangered or threatened, and expeditious progress is being made to add
or remove qualified species from the Federal Lists of Endangered and
Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires
that we treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, that is, requiring a subsequent finding to be made within 12
months. We must publish these 12-month findings in the Federal
Register.
Previous Federal Actions
On July 30, 2007, we received a petition dated July 24, 2007, from
Forest Guardians (now WildEarth Guardians), requesting that the
Service: (1) Consider all full species in our Mountain Prairie Region
ranked as G1 or G1G2 by the organization NatureServe, except those that
are currently listed, proposed for listing, or candidates for listing;
and (2) list each species as either endangered or threatened. The
petition included the northern leatherside chub (Lepidomeda copei),
which is addressed in this finding. The petition incorporated all
analysis, references, and documentation provided by NatureServe in its
online database at https://www.natureserve.org/into the petition. The
document clearly identified itself as a petition and included the
petitioners' identification information, as required in 50 CFR
424.14(a). We sent a letter to the petitioners, dated August 24, 2007,
acknowledging receipt of the petition and stating that, based on
preliminary review, we found no compelling evidence to support an
emergency listing for any of the species covered by the petition.
On March 19, 2008, WildEarth Guardians filed a complaint (1:08-CV-
472-CKK) indicating that the Service failed to comply with its
mandatory duty to make a preliminary 90-day finding on their two
multiple species petitions--one for mountain-prairie species, and one
for southwest species.
On February 5, 2009 (74 FR 6122), we published a 90-day finding on
165 species from the petition to list 206 species in the mountain-
prairie region of the United States as endangered or threatened under
the Act. We found that the petition did not present substantial
scientific or commercial information indicating that listing was
warranted for these species and, therefore, did not initiate further
status reviews in response to the petition. Two additional species were
reviewed in a January 6, 2009, 90-day finding (74 FR 419) and,
therefore, were not considered further in the February 5, 2009, 90-day
finding. For the remaining 39 species, we deferred our findings until a
later date. One species of the 39 remaining species, Sphaeralcea
gierischii (Gierisch mallow), was already a candidate species for
listing; therefore, 38 species remained. On March 13, 2009, the Service
and WildEarth Guardians filed a stipulated settlement in the District
of Columbia Court, agreeing that the Service would submit to the
Federal Register a 90-day finding on the remaining 38 mountain-prairie
species by August 9, 2009.
On August 18, 2009, we published a notice of 90-day finding (74 FR
41649) on 38 species from the petition to list 206 species in the
mountain-prairie region of the United States as endangered or
threatened under the Act. Of the 38 species, we found that the petition
presented substantial scientific and commercial information for 29
species indicating that a listing may be warranted. The northern
leatherside chub addressed in this 12-month finding was included in the
list of 29 species. We initiated a status review of the 29 species to
determine if listing was warranted. We also opened a 60-day public
comment period to allow all interested parties an opportunity to
provide information on the status of the 29 species. The public comment
period closed on October 19, 2009. We received 224 public comments. Of
these, five specifically mentioned northern leatherside chub. All
substantial information we received was carefully considered in this
finding. This notice constitutes the 12-month finding on the July 24,
2007, petition to list the northern leatherside chub as endangered or
threatened.
Species Information
The northern leatherside chub (Lepidomeda copei) is a rare desert
fish in the minnow family (Cyprinidae) that occurs in northern Utah and
Nevada, southern and eastern Idaho, and western
[[Page 63445]]
Wyoming (Johnson et al. 2004, pp. 842-843; Utah Division of Wildlife
Resources (UDWR) 2009, pp. 28-30; McAbee 2011, entire). The species is
native to smaller, mid-elevation, desert streams in the northeastern
portions of the Great Basin region (draining to the Great Salt Lake)
and the southern and eastern portions of the Pacific Northwest Region
(draining to the Pacific Ocean) (Johnson et al. 2004, pp. 842-843; UDWR
2009, pp. 28-30). Like many western North American non-game fish
species, little was known about its biology, ecology, or status until
recently (Belk and Johnson 2007, pp. 67-68).
Taxonomy and Species Description
The northern leatherside chub is one of two species, along with the
southern leatherside chub (Lepidomeda aliciae), recently re-classified
from the single species `leatherside chub' (Snyderichthys copei or Gila
copei) (Johnson et al. 2004, pp. 841, 852). Throughout the remainder of
this finding, references to leatherside chub indicate data collected
before the two species were delineated, and references to southern
leatherside chub and northern leatherside chub indicate data specific
to each species, exclusively. Because the northern and southern species
were only recently separated, most species descriptions and life-
history investigations are a combination of the two species. While many
characteristics are common to both species, we will describe
characteristics of only the northern leatherside chub when possible.
The taxonomic history of leatherside chub is complex. Even when
considered a single species, taxonomists classified the leatherside
chub in at least seven different genera over the past century and a
half (Johnson et al. 2004, p. 841). The type locality for leatherside
chub (Squalius copei; Jordan and Gilbert 1881) is from the Bear River
at Evanston, Wyoming (UDWR 2009, p. 24). Classification by Miller in
the mid-twentieth century (1945) placed leatherside chub in the
monotypic genus Snyderichthys, but shortly thereafter Uyeno (1960)
assigned it to the genus Gila (the chubs), subgenus Snyderichthys (UDWR
2009, p. 25). Many fisheries texts accepted Gila copei as the taxonomic
classification over the next 40 years (Sigler and Miller 1963, p. 74;
Sigler and Sigler 1996, p. 77), but acceptance was not unanimous, as
evidenced by the American Fisheries Society supporting Snyderichthys
copei in 2004 (UDWR 2009, p. 25). Taxonomic discrepancy was not fully
rectified until a short time ago. Recent research demonstrated that
what was previously considered the `leatherside chub' is in fact two
distinct species with discrete geographic, ecological, morphological,
and genetic characteristics (Johnson et al. 2004, pp. 841, 852).
Moreover, neither species belongs in the previously accepted genera,
but rather both belong in the genus Lepidomeda, a group commonly
referred to as the spinedaces (Johnson et al. 2004, pp. 841, 852).
Three different species concepts validate this taxonomic revision.
Genetic analysis endorses two evolutionarily separate species under the
phylogenetic species concept (defines a species as a set of organisms
with a unique genetic history) (Johnson and Jordan 2000, pp. 1029,
1033; Johnson et al. 2004, pp. 841, 851). In addition, morphologic
(cranial shape) and ecological (feeding and growth rates) divergence
support two distinct species under the similarity and ecological
species models, respectively (Johnson et al. 2004, p. 851). It also is
worth noting that current taxonomy aligns with discrete geographic
distributions of the species, with the unoccupied Weber River
separating the two species' ranges and the uninhabitable Great Salt
Lake preventing natural interaction between individuals of the two
species (Belk and Johnson 2007, p. 69). Supported by multiple lines of
evidence indicating that southern (Lepidomeda aliciae) and northern (L.
copei) leatherside chub are two distinct species, the American
Fisheries Society now recognizes the two species as such (Jelks et al.
2008, p. 390). Because northern leatherside chub is an acknowledged
species, it is a listable entity under the Act.
The northern leatherside chub is a small fish, less than 150
millimeters (mm) (6 inches (in.)) in length, that received its common
name from the leathery appearance created by small scales on a trim,
tapering body (Sigler and Sigler 1996, p. 78; UDWR 2009, p. 26). It has
rounded dorsal and anal fins, each with eight fin rays (Sigler and
Sigler 1996, p. 78). Typically, the northern leatherside chub is bluish
above and silver below, but orange to red coloration may occur on some
fins (Sigler and Sigler 1996, p. 78). Males also have a golden-red
speck at the upper end of the gill opening and between the eyes and the
upper jaw (Sigler and Sigler 1996, p. 78).
Two characteristics that distinguish northern and southern
leatherside chubs from each other are cranial shape and size-at-age
(UDWR 2009, p. 26). Northern leatherside chub have deeper heads with
shorter snouts (Johnson et al. 2004, p. 850) and are typically 15
percent smaller than southern leatherside chub of the same age, with
northern leatherside chub reaching total length of approximately 60 mm
(2.4 in.) at age 2 and 71 mm (2.8 in.) at age 3 (Belk et al. 2005, pp.
177, 181).
Life History
Before 1995, the life history of the leatherside chub was not well
known, with just a few observations of age, growth, or reproduction
(Johnson et al. 1995, p. 183). Investigations of populations now known
as southern leatherside chub demonstrated the species could live up to
8 years and reached sexual maturity at age 2 (Johnson et al. 1995, p.
185). Further work corroborated that the majority of northern
leatherside chub also mature at age 2, but some not until age 4 (Belk
et al. 2005, p. 181).
The bulk of our reproductive knowledge about this species comes
from the hatchery setting, where successful propagation has occurred.
Northern leatherside chub produce translucent, whitish fertilized eggs
that are adhesive and can clump together or adhere to substrate
(Billman et al. 2008a, p. 277). In natural populations, eggs typically
hatch in late June (Belk et al. 2005, p. 181), but in hatchery
conditions, spawning occurs between April and September (Billman et al.
2008a, p. 276). In controlled hatchery conditions, eggs hatch between 4
and 6 days to produce fry that still reside in the substrate (Billman
et al. 2008a, p. 277). Six days after hatching, fry emerge from the
substrate, and by 40 days after hatching most have tripled in length to
approximately 16 mm (0.63 in.) (Billman et al. 2008a, p. 277).
In the hatchery setting, spawning overwhelmingly occurs over cobble
substrate (which provides interstitial space for eggs) and in higher
velocity flows (which provide oxygen and remove fine sediment) (Billman
et al. 2008a, p. 277). These conditions indicate main channel riffle or
run habitats are likely the natural location of northern leatherside
chub spawning.
Northern and southern leatherside chub have similar, relatively
broad diets, with aquatic and terrestrial insects and crustaceans
accounting for 75 percent of their consumption in one study (Bell and
Belk 2004, p. 414). Aquatic and terrestrial insects dominated the
autumnal northern leatherside chub diet at the Sulphur Creek sample
site (Bell and Belk 2004, p. 414). The species foraged on a wide
variety of prey items common to both the substrate and stream drift
(Bell and Belk 2004, p. 414). However, it is likely
[[Page 63446]]
that the species' diet varies throughout the year and at different
locations based on available food (Bell and Belk 2004, p. 414). The
study results indicate that the species' diet overlaps with other
native and nonnative fish, including sculpins (Cottidae family),
shiners (Cyprinids), and cutthroat (Oncorhynchus clarkii) and brown
(Salmo trutta) trout, suggesting possible competitive interactions
(Bell and Belk 2004, p. 414).
Habitat
Northern leatherside chub inhabit small desert streams between
elevations of approximately 1,250 to 2,750 meters (m) (4,100 to 9,000
feet (ft)) in the Bear, Snake, and Green River subregions (as defined
by the U.S. Geological Survey's (USGS) National Hydrography Dataset
(NHD)) (Idaho Department of Fish and Game (IDFG) 2005, p. 1). Streams
of this nature encounter extreme seasonal and annual physical
conditions because of variation in temperature and precipitation
(Wilson and Belk 2001, p. 40). Therefore, northern leatherside chub
must endure cold winters and hot summers (water temperature from 0 to
25 [deg]C (32 to 77 [deg]F); high, turbid spring runoff and low, clear
summer base flows; and periodic droughts that reduce water in streams
(Wilson and Belk 2001, p. 40). It is likely that enduring these
variable extreme habitat conditions adapted northern leatherside chub
to tolerate varied habitat conditions.
Most habitat descriptions are the result of investigations before
leatherside chub was divided into two species, but habitat descriptions
for the northern leatherside chub can be evaluated based on their
distinct geographic range. Summer water temperature of occupied habitat
is reportedly 10 to 23 [deg]C (50 to 73.4 [deg]F), but the current
belief is that northern leatherside chub's range is actually restricted
to 15.5 to 20 [deg]C (59.9 to 68 [deg]F) (UDWR 2009, p. 27). The
species does not persist in lakes or reservoirs (UDWR 2009, p. 27).
Northern leatherside chub prefer low water velocities (15 to 23
centimeters per second (cm/s) (0.5 to 0.75 feet per second (fps)), and
their probability of occurrence decreases at higher velocities (UDWR
2009, p. 40). Water velocity and temperature generally limit the
northern leatherside chub from occupying high headwater streams. Recent
habitat investigations show that northern leatherside chub habitat
associations are consistent with the results for the southern species
(Belk and Wesner 2010, p. 12), allowing us to consider habitat data for
southern leatherside chub as generally acceptable for northern
leatherside chub.
Distribution
Recent and ongoing investigations continue to revise the current
and historical distributions of northern leatherside chub by verifying
or invalidating historical specimens, intensely resampling specific
stream reaches suspected to harbor the species, and documenting new
northern leatherside chub occurrences. For this finding, we completed a
white paper summarizing current and historical distributions through
fall 2010 (McAbee 2011, entire). We analyzed current and historical
range at the subbasin level (otherwise known as 8-digit Hydrologic Unit
Code (HUC) in the USGS' NHD or HUC8), and current population locations
at the subwatershed level (otherwise known as 12-digit HUC or HUC12).
We identified population locations in one to multiple subwatersheds,
depending on the perceived interaction between individuals. State
wildlife agencies and universities reviewed the document to ensure that
it summarized their data collection correctly. Information from our
population summary (also known as `white paper') is used throughout
this finding to inform our conclusions (McAbee 2011, entire).
The documented historical range of northern leatherside chub
includes portions of the Bear River subregion that drain to the Great
Salt Lake, and discontinuous subbasins in the Upper Snake River
subregion that eventually drain to the Pacific Ocean (Figure 1; Table
1). It is unclear how this species came to inhabit two presently
unconnected hydrologic regions. Past geologic events associated with
the draining of Lake Bonneville or the connection of the Bear River to
the Snake River as recently as 30,000 years ago (Behnke 1992, p. 134)
are likely responsible for the separation (UDWR 2009, p. 25). The range
of northern leatherside chub has declined over the past 50 years
(Wilson and Belk 2001, p. 36; Johnson et al. 2004, pp. 841-842; UDWR
2009, p. 24), and the verified current range of the species is now
limited to five of the eight documented historical subbasins (Table 1).
However, additional survey efforts are planned or ongoing.
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Table 1--Documented Range of the Northern Leatherside Chub by Subbasin
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
NATIONAL HYDROGRAPHY DATASET LOCATIONS
Status
----------------------------------
Subregion (code) Subbasin code and name
----------------------------------------------------------------------------------------------------------------
Bear River (1601)................ 16010101 Upper Bear River.... Currently occupied.
16010102 Central Bear River
16010203 Logan River......... Historical records only.
16010204 Lower Bear River
Upper Snake River (1704)......... 17040101 Snake Headwaters.... Currently occupied.
17040105 Salt River
17040211 Goose Creek
17040221 Little Wood River... Historical records only.
Upper Green River (1404)......... 14040103 Upper Green--Slate Currently occupied but unconfirmed
Creek. native range.
14040107 Blacks Fork
----------------------------------------------------------------------------------------------------------------
In addition to the historical range, two populations are now known
from the Upper Green River subregion in the Colorado River region
(Table 1). It is possible that these occurrences are the result of
human introductions. However, genetic analysis is necessary to confirm
the origin of these populations, and this information is not yet
available. For the purposes of this finding, we acknowledge these
populations' conservation value.
Because verifiable, historical records are sparse, we are unable to
produce a large-scale historical range boundary with this information.
Therefore, we rely on the known, verified collections to analyze the
status of the species.
Northern leatherside chub are difficult to identify in the field
because they can be confused with other species with similar
appearances. Therefore, many collections were incorrectly classified as
northern leatherside chub, when in fact they were later verified as
Utah chub (Gila atraria), speckled dace (Rhinichthys osculus), or
redside shiner (Richardsonius balteatus). Ichthyologists at Brigham
Young and Idaho State Universities worked to verify historical records
and validate recent collections in order to authenticate data. As a
result, many previously accepted collections were refuted, leading to a
clearer understanding of the species' range (Northern Leatherside Chub
Conservation Team 2010, p. 4). In fact, many subbasins once identified
as part of the species' current or historical range are now either
questioned or invalidated (Table 2). While we expect that the northern
leatherside chub's natural distribution is more continuous than
verifiable historical and current data indicate, we have no specific
data to describe this range other than what is presented in this
finding (Figure 1; Table 3).
Table 2--Suspected Subbasins That Are No Longer Considered Northern Leatherside Chub Current or Historical Range
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
NATIONAL HYDROGRAPHY DATASET LOCATIONS
Status
-------------------------------------
Subregion (code) Subregion code and name
----------------------------------------------------------------------------------------------------------------
Upper Snake River (1704)............ 17040207 Blackfoot River........ Historical specimen
incorrectly classified; No
verified records.
17040210 Raft River............. Unvouchered historical
record not corroborated by
recent sampling; No
verified records.
17040213 Salmon Falls Creek..... Unvouchered recent record
not corroborated by
repeated sampling; No
verified records.
17040219 Big Wood River......... Unvouchered recent record
not corroborated by
repeated sampling; No
verified records.
----------------------------------------------------------------------------------------------------------------
Middle Snake (1705)................. unknown Bruneau & Snake Rivers. Historical specimens
incorrectly classified; No
verified records.
17050104 Upper Owyhee........... Museum records need to be
checked.
----------------------------------------------------------------------------------------------------------------
Great Salt Lake (1602).............. 16020309 Curlew Valley.......... Listed in conservation
agreement, but no
supporting data; No
records.
----------------------------------------------------------------------------------------------------------------
Table 3--Extant Populations of Northern Leatherside Chub in 2010
----------------------------------------------------------------------------------------------------------------
NATIONAL HYDROGRAPHY DATASET LOCATIONS
----------------------------------------------------------------- POPULATION NAME STATE
Subregion Subbasin
----------------------------------------------------------------------------------------------------------------
Bear River............................ Upper Bear.............. Upper Mill/Deadman Creeks.... UT/WY
Upper Sulphur/La Chapelle WY
Creeks.
[[Page 63449]]
Yellow Creek................. UT/WY
Upper Twin Creek............. WY
Rock Creek................... WY
-------------------------------------------------------------------------
Central Bear............ Dry Fork Smiths Fork......... WY
Muddy Creek.................. WY
----------------------------------------------------------------------------------------------------------------
Snake River........................... Snake Headwaters........ Pacific Creek................ WY
Salt River.............. Jackknife Creek.............. ID
-------------------------------------------------------------------------
Goose Creek............. Trapper Creek................ ID
Beaverdam Creek.............. ID
Trout Creek.................. NV/ID
----------------------------------------------------------------------------------------------------------------
Green River........................... Upper Green River/Slate North Fork Slate Creek....... WY
Creek.
Blacks Fork............. Upper Hams Fork.............. WY
----------------------------------------------------------------------------------------------------------------
Overall, our identification and confirmation of a northern
leatherside population for this finding required the presence of
multiple age classes, collection of a dense number of fish (more than
five individuals), and documentation of fish collections over multiple
years. Meeting these criteria demonstrated to us that northern
leatherside chub populations were resident, reproducing, and persisting
over time. Within the current range of the northern leatherside chub,
we thus delineated 14 extant populations, spread across the Bear (7),
Snake (5), and Green (2) River subregions (Table 3). Locations where
northern leatherside chub were collected, but were not classified as a
population, are detailed in our white paper analysis (McAbee 2011,
entire).
Bear River Subregion
The Bear River subregion harbors seven extant populations of
northern leatherside chub across two subbasins: Five in the Upper Bear
River subbasin and two in the Central Bear River subbasin (Table 3). We
are aware of the presence of some individual fish upstream (Hayden and
Stillwater Forks) (Nadolski and Thompson 2004, pp. 3, 4, 7; Chase 2010,
pers. comm.) and downstream (mainstem Bear River and lower Sulphur
Creek) (Wyoming Game and Fish Department (WGFD) 2008, pp. 1, 3; Belk
and Wesner 2010, p. 5) of these areas; however, we do not consider
these as populations because they do not meet the definition of a
population outlined above (specifically presence of multiple age
classes and collection of a dense number of fish) due to their low
densities and lack of juvenile fish.
In the Upper Bear River subbasin, the Upper Mill/Deadman Creeks and
Yellow Creek populations harbor dense, reproducing populations of
northern leatherside chub (McKay and Thompson 2010, pp. 4-7). In the
Upper Mill/Deadman Creeks population, approximately 1,000 individuals
per kilometer are found in Deadman Creek (McKay and Thompson 2010, pp.
6-7) and groups occur downstream in Mill Creek in Utah and Wyoming
(Nadolski and Thompson 2004, pp. 3, 7; Belk and Wesner 2010, p. 5). The
Yellow Creek population has groups of individuals from the upper
reaches in Utah downstream through Wyoming and in Thief Creek, a
tributary (Thompson et al. 2008, pp. 8-9; Zafft et al. 2009, p. 3; Belk
and Wesner 2010, p. 5). The Upper Sulphur/La Chapelle Creeks population
above Sulphur Creek Reservoir also harbors abundant northern
leatherside chubs (Zafft et al. 2009, p. 3). This population is likely
isolated by the presence of Sulphur Creek Reservoir, which is
unsuitable habitat and is stocked with predatory nonnative trout (brown
trout before 2000, rainbow trout (Oncorhynchus mykiss) currently) (WGFD
2010, pp. 3-6).
Twin Creek, a large tributary to the Bear River in the Upper Bear
River subbasin, contains two populations of northern leatherside chub:
Rock Creek and Upper Twin Creek. Multiple tributaries to Twin Creek
comprise the Upper Twin Creek population, including Clear Creek and the
North, East, and South Forks of Twin Creek (Belk and Wesner 2010, p. 5;
Colyer and Dahle 2010, p. 5). These populations can presumably interact
but are likely isolated from all other populations because sampling has
failed to detect downstream emigrants (McKay and Thompson 2010, p. 18).
In the Central Bear River subbasin, the Smiths Fork area harbors at
least two large populations: Dry Fork Smiths Fork and Muddy Creek. Both
contain hundreds of individuals (Colyer and Dahle 2007, p. 8; Belk and
Wesner 2010, p. 5). Individual fish from this population can disperse
downstream, but many perish in irrigation canals before reaching the
mainstem Bear River (Roberts and Rahel 2008, pp. 951, 955).
Snake River Subregion
The Snake River subregion contains eight subbasins with historical
northern leatherside chub observations (UDWR 2009, pp. 44, 48).
However, biologists have reexamined museum records, resampled stream
reaches with presumed past observations, and refined the identification
key for the species. As a result, four of the eight subbasins, the
Raft, Big Wood, and Blackfoot Rivers, and Salmon Falls Creek, with past
records were downgraded to ``unlikely to have contained or to contain
northern leatherside chub'' (Table 2). One subbasin has verified
historical records but no current records (Little Wood River), and is
thus considered extirpated unless new information is obtained.
The remaining three subbasins with verified current records are
Goose Creek, Snake Headwaters, and Salt River (Table 1; McAbee 2011, p.
2). Within the Goose Creek subbasin, we know of three reproducing
populations at Trapper, Beaverdam, and Trout Creeks. All three
populations have persisted over the past 10 to 15 years (Grunder et al.
1987, p. 80; Wilson and Belk 1996, p. 17; Keeley 2010, pp. 3-29).
Trapper Creek is isolated from the other two by Oakley Reservoir, but
there are no barriers between Trout and Beaverdam Creeks, and the
populations likely interact. Collections of single northern
[[Page 63450]]
leatherside chub individuals in mainstem Goose Creek (Keeley 2010, pp.
24-29) indicate individuals may be dispersing from these two
populations. Recent collections of individuals in Pole Creek in the
Goose Creek subbasin suggest a population may occur in this tributary
as well (Grunder 2010, p. 3). However, no juvenile fish were collected,
and this is the first year northern leatherside were documented in this
reach (Keeley 2010, pp. 6-11). Although these collections may
constitute a colonization event, we do not consider Pole Creek a
population in this finding because multiple age classes were not
present (demonstrating the area has not shown successful reproduction
or recruitment).
The single population in the Snake Headwaters subbasin is Pacific
Creek, which has persisted since its discovery in the 1950s (Grand
Teton National Park 2009, pp. 1-2; Zafft et al. 2009, pp. 2-5). In the
Salt River subbasin, a single population is found in Jackknife Creek
and its tributaries (Isaak and Hubert 2001, pp. 26-27; Keeley 2010, pp.
45-60). The Pacific Creek population is separated from the Jackknife
Creek population by large stream distances and large reservoirs, making
individual dispersal between the two populations unlikely. In addition,
both the Pacific Creek and Jackknife Creek populations are isolated
from the Goose Creek subbasin by upwards of 350 stream-kilometers (km)
and many large reservoirs.
Green River Subregion
There are two northern leatherside chub populations in the Green
River subregion, one each in the Upper Green River/Slate Creek and
Blacks Fork subbasins (Table 3). However, based on the lack of
historical collections in the Green River subregion, the lack of a
documented natural connection between the Green River subregion and the
Bear or Snake River subregions, and the prevalence of human
translocations of fish, we determine that it is unlikely that this is
the species' native range. The first population was identified in 1988
in North Fork Slate Creek (WGFD 1988 in Zafft et al. 2009, p. 2), and
represented the first population outside the Bear or Snake River
subregions. This population is approximately 30 km (18 mi) east of the
Bear and Snake River subregions, making it close enough to be the
result of a human introduction. The Upper Hams Fork population was
later identified (Wheeler 1997 in Zafft et al. 2009, p. 3), and is
located approximately 35 km (22 mi) northeast of the North Fork Slate
Creek population. In addition, this population is just across the
subregion boundary with the Dry Fork Smiths Fork population, making it
even more possible that the population is the result of a human
introduction. We also are aware of individual fish in the nearby West
Fork of the Hams Fork in 2006 (Zafft et al. 2009, p. 3), which we
include as part of the Upper Hams Fork population because they can
interact.
These two populations indicate that northern leatherside chub are
persisting in the Green River subregion. Whether these populations are
native, or are recent human introductions, has yet to be resolved.
Genetic analysis to answer this question is planned for completion in
the near future, and will hopefully resolve this question. Until proof
can be presented that these populations are not native, their
conservation value to the species must be considered.
It is worth noting that genetic analysis of southern leatherside
chub collections in the Fremont River (Green River subregion)
demonstrated that they were not native, but rather a genetic match to
an East Fork Sevier River population (Barrager and Johnson 2010, p. 7).
These results show that a successful human translocation of a surrogate
species has occurred, and is possible for the northern leatherside
chub.
In summary, 14 extant northern leatherside chub populations persist
across 3 subregions: 7 populations in the Bear River subregion; 5
populations in the Snake River subregion; and 2 populations in the
Green River subregion (Figure 1, Table 1). Land ownership is comprised
of privately owned land (31.5 percent in the States of Idaho, Nevada,
Utah, and Wyoming), as well as lands managed by BLM (30 percent), NPS
(3.5 percent), USFS (30.5 percent), and the States of Wyoming (4.3
percent) and Idaho (0.04 percent) (Service 2011, pp. 11-17). We will
investigate threats to these extant populations in the remainder of
this finding.
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following five factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
In making our 12-month finding on the petition we considered and
evaluated the best available scientific and commercial information.
Information pertaining to the northern leatherside chub in relation to
the five factors provided in section 4(a)(1) of the Act is discussed
below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
The following potential threats that may affect the habitat or
range of northern leatherside chub are discussed in this section,
including: (1) Livestock grazing; (2) oil and gas development; (3)
mining; (4) water development; (5) water quality; and (6) fragmentation
and isolation of existing populations.
Livestock Grazing
Livestock presence generally disturbs streamside and instream
habitats, particularly in the arid west where riparian and stream
habitats are fragile ecosystems (Kauffman and Krueger 1984, p. 431;
Helfman 2007, p. 102). Livestock grazing is especially detrimental to
riparian habitats because livestock spend disproportionately more time
near water (Helfman 2007, p. 102). They typically eat and trample
riparian vegetation and compact soil, which leads to impacts that
include increased sediment inputs from runoff, nutrient loading from
livestock waste, higher stream temperatures from lack of vegetation
shading, and reduction in invertebrate abundance (Kauffman and Krueger
1984, p. 432; Wohl and Carline 1996, p. 264; Stoddard et al. 2005, p.
8). These impacts combine to degrade habitats for many fish species,
especially species requiring cool, clear water and gravel substrate,
such as salmonids (Helfman 2007, p. 34).
However, some species, such as the northern leatherside chub, can
tolerate certain habitat changes and persist despite disturbed
conditions. Increased sediment may alter a fish community and allow for
domination by species that thrive or contend well with sandy substrates
(Sutherland et al. 2002, pp. 1801-1802) (see Water Quality section for
specific discussion of sedimentation and northern leatherside chub).
Similarly, increased water temperature also may alter the distribution
of species, forcing out cold-water species,
[[Page 63451]]
and allowing for warm-water species to enter a habitat (Field et al.
2007, p. 631). Northern leatherside chub apparently can tolerate
certain disturbances, largely because they can survive extreme
environmental conditions to which they are evolutionarily adapted (Belk
and Johnson 2007, p. 70), such as high water temperatures (Isaak and
Hubert 2001, p. 27; Wilson and Belk 2001, p. 39), with a critical
thermal maximum of approximately 30 [deg]C (86 [deg]F) (Billman et al.
2008b, p. 463) and persist in large numbers in areas deemed degraded
(Muddy Creek and Upper Twin Creek). However, we do not have specific
data indicating their tolerances to all water quality conditions. While
habitats impacted by grazing may not be preferred, populations of
northern leatherside chub persist in locations deemed degraded and
impaired.
For example, in the Bear River subregion, the Upper Twin Creek
population persists even though overgrazing has reduced the riparian
vegetation cover (Colyer and Dahle 2010, pp. 16, 19) to the point that
the streams are classified as degraded (BLM 2011, entire). In the same
subregion, Muddy Creek is another example of a dense northern
leatherside chub population that persists (Colyer and Dahle 2007, Table
6) despite altered conditions from overgrazing that result in a very
wide, shallow channel and degraded riparian habitats (BLM 1999, p. 7;
BLM 2007a, pp. 1-2; Prichard 1998, p. 8; BLM 2005, p. 5). In the Snake
River subregion, populations persist in Beaverdam and Trapper Creeks
although the water quality in both streams is impaired, most likely as
the result of overgrazing (Lay 2003, pp. 69-70, 125). However, it is
worth noting that impacts from grazing affect Beaverdam and Trapper
Creeks in qualitatively different ways (high suspended sediment) than
Muddy and Upper Twin Creeks (reduced riparian cover).
Data indicate that some level of livestock grazing occurs across
the entire range of the northern leatherside chub and near all existing
populations (Service 2011, pp. 18-24). Because of the prevalence of
grazing across the western United States, the species will likely
encounter livestock grazing effects. However, we expect effects from
livestock grazing will decrease over time on Federally managed lands as
management agencies address livestock grazing practices. For example,
the U.S. Forest Service (USFS) recently implemented changes in the
grazing management on the Goose Creek grazing allotment that occurs in
the upstream portions of Beaverdam and Trout Creeks (Northern
Leatherside Chub Conservation Team 2011, p. 3). On a broader scale,
Bureau of Land Management (BLM) guidelines in Idaho (BLM 1997, p. 4,
Standard 2), Wyoming (BLM 2007c, p. 1, Standard 2),
Utah (BLM 2009, p. 1, Standard 1b), and Nevada (BLM 2007b, p.
1, Standard 2) require all streams to have riparian health
consistent with natural, functional habitats, indicating that grazing
impacts will be improving on BLM lands. Upstream land ownership for all
but three occupied sub-watersheds (11 of 14) is over 50 percent
federally owned, demonstrating the importance of Federal land
management for northern leatherside chub (see detailed discussion of
land ownership under Factor D below).
In summary, there is no apparent indication that grazed areas are
negatively impacting existing populations of northern leatherside,
although grazing has likely affected water quality (discussed later).
Populations of northern leatherside chub occur in a wide variety of
habitat conditions, from unaltered locations to those with heavily
altered riparian conditions impacted by livestock grazing practices. In
fact, some of the densest populations occur in areas that are heavily
grazed. Also, there is evidence to indicate that livestock grazing
impacts will be declining in the future, as more sustainable rangeland
management practices are applied. We found no information that grazing
may act on this species to the point that the species itself may be at
risk, nor is it likely to become so.
Oil and Gas Development
Oil and gas exploration and development can impact fish habitats,
primarily through degraded watershed health. Increased land disturbance
from roads and pads reduce water quality because of increased sediment
loads (WGFD 2004, p. 25; Matherne 2006, p. 1). Road culverts also can
fragment fish habitats if they are designed in a way that impedes fish
migration (Aedo et al. 2009, p. 2). Drilling operations often require
water depletions from local water sources and can result in accidental
spills of contaminants into fish habitat (Stalfort 1998, p. ES-2; Etkin
2009, pp. 35-42). Accumulations of contaminants, such as hydrocarbons
and produced water (water locked away in formation with oil and gas
that is typically not suitable for human or wildlife use), can result
in lethal or sublethal impacts across the entire aquatic food chain,
including sensitive fish species (Stalfort 1998, Section 4). Water
depletions can reduce or eliminate aquatic habitat, creating multiple
negative effects (see Water Development, below).
To analyze the potential impacts from oil and gas development, we
investigated past and present levels of development and the potential
for future development in occupied populations. We summarized the
analysis in an internal white paper (Hotze 2011, pp. 1-8) and reference
the results throughout this finding. Data sources for the investigation
included Bureau of Land Management Resource Management Plans (BLM 1985,
entire; BLM 2010, entire); State databases of oil and gas development
(Hess et al. 2008, entire; Utah Division of Oil, Gas, and Mining 2009,
entire; Wyoming Oil and Gas Conservation Commission 2009, entire; State
of Idaho 2011, entire); and energy development maps (Garside and Hess
2007, map; Energy Information Administration (EIA) 2009a, map; EIA
2009b, map; EIA 2011, entire).
TABLE 4--Summary of Oil and Gas Development in Extant Northern Leatherside Chub Populations
----------------------------------------------------------------------------------------------------------------
National hydrography dataset locations Overlap with
-------------------------------------------------- Active oil & known coalbed
Population name State gas wells methane
Subregion Subbasin (inactive) reserves (%)
----------------------------------------------------------------------------------------------------------------
Bear River.................... Upper Bear....... Upper Mill/ UT/WY 0 (6) 4
Deadman Creeks.
Upper Sulphur/La WY 2 (1) 47
Chapelle Creeks.
Yellow Creek.... UT/WY 28 (63) 25
Upper Twin Creek WY 0 (0) 9
[[Page 63452]]
Rock Creek...... WY 0 (1) 131
Central Bear..... Dry Fork Smiths WY 0 (0) 0.1
Fork.
Muddy Creek..... WY 0 (0) 0
Snake River................... Snake Headwaters. Pacific Creek... WY 0 (0) 0
Salt River....... Jackknife Creek. ID 0 (0) 16.6
Goose Creek...... Trapper Creek... ID 0 (0) 0
Beaverdam Creek. ID 0 (0) 0
Trout Creek..... NV/ID 0 (0) 0
Green River................... Upper Green River/ North Fork Slate WY 0 (5) 32
Slate Creek. Creek.
Blacks Fork...... Upper Hams Fork. WY 0 (0) 0
----------------------------------------------------------------------------------------------------------------
We found that throughout the range of northern leatherside chub,
neither active development nor potential for future development of oil
and gas are common, with both being limited to one localized area, the
Yellow Creek population in the Bear River subregion (Table 4) (Hotze
2011, pp. 1-8). A quarter of the Yellow Creek population overlaps with
proven Federal oil and gas reserves, mostly in the western and northern
portions of the subwatershed (EIA 2009a, map; Hotze 2011, p. 5).
Current and past well activity follow this overlap, with 63 inactive
and 28 active wells in the population's subwatershed, mainly near the
occupied areas of Thief Creek and lower Yellow Creek in Wyoming (Hotze
2011, p. 2). No development activity has occurred in the upstream
portions of Yellow Creek, which contain high densities of northern
leatherside chub, and no proven Federal oil and gas reserves occur
there. A quarter of the Yellow Creek population overlaps with coalbed
methane reserves, in the eastern-central portion in Wyoming, suggesting
the potential for development (Hotze 2011, p. 7).
The populations in the northern portions of the Bear River
subregion have seen little past or current development and have a low
probability of future development. The Twin Fork drainage has only one
inactive well across the Rock and Upper Twin Creek populations (Hotze
2011, p. 2). A small portion (less than 1 percent) of the Rock Creek
population overlaps with the Collett Creek field, which contains proven
Federal oil and gas reserves (Hotze 2011, pp. 4-5). The Smiths Fork
drainage is north of the Wyoming Thrust Belt (an optimal geologic
formation for retrieving oil and gas resources), so development of oil
reserves has not historically occurred in the Muddy Creek and Dry Fork
Smiths Fork populations, and is not likely to occur in the future
(Hotze 2011, p. 2). Similarly, there is very little overlap between
these two populations and known coalbed reserves (less than 1 percent
of the Dry Fork Smiths Fork population) (Hotze 2011, p. 7), making it
unlikely that coalbed methane development will take place in these
populations.
In the remainder of the Bear River subregion, past and current
resource development is rare, but resource potential exists. The Upper
Sulphur/La Chapelle Creeks population has only one inactive and two
active wells, but half of the population area overlaps with coalbed
methane reserves (Hotze 2011, pp. 2, 7). However, the area has a low
potential for resource extraction demonstrated by the low presence of
current or past wells and the distance to the closest producing well.
The Upper Mill/Deadman Creeks population has only six inactive wells,
all in the Utah portion of the population's subwatershed (Hotze 2011,
p. 2). Less than 5 percent of the Upper Mill/Deadman Creeks population
overlaps with coalbed methane reserves, all in the most downstream
reaches that do not contain northern leatherside chub (Hotze 2011, p.
7).
The Snake River subregion populations occur in areas that do not
have active development and are characterized as low potential for
future development (Hotze 2011, pp. 1-2). Currently, all populations in
the Goose Creek subbasin (Trout, Trapper, and Beaverdam Creeks) are in
areas open for oil and gas leasing, but there are no producing wells in
either the Idaho or Nevada portions (Hotze 2011, p. 2). Further east,
there is potential for development of the Idaho-Wyoming Thrust Belt in
the Jackknife Creek population, but the probability of discovering and
developing oil in this area is considered low by BLM (BLM 2010, p. Q-
1). No wells are currently found in the Jackknife Creek population
(Hotze 2011, p. 2). Finally, the Pacific Creek population may overlap
with the Jackson Hole coalbed methane field, but management by Grand
Teton National Park makes it unlikely that development of these
resources will take place (Hotze 2011, p. 2).
In the portions of the Green River subregion occupied by northern
leatherside chub, there is little active or historical development of
any kind and minor potential for future development exists, chiefly
from coalbed methane reserves. The Upper Hams Fork is outside of any
known coalbed reserves, the population is north of the Wyoming Thrust
Belt and west of the Wyoming Overthrust coalbed reserves (Hotze 2011,
pp. 2, 7). As a result, it has no active or inactive wells within its
boundary, and we consider future development potential in this
population negligible (Hotze 2011, p. 2). The North Fork Slate Creek
population has only five inactive wells within its boundary, but
overlaps with the Wyoming Overthrust coalbed reserves in the upstream
third of the population (Hotze 2011, pp. 2, 7). It is possible that
development could occur in this population, but we have no data to
indicate that development is planned or imminent. Also, without
environmental planning for this development, we cannot say what impacts
the development would have on northern leatherside chub.
To summarize, past, present, and future oil and gas development is
likely to impact one population of northern leatherside chub, Yellow
Creek in the Bear River subregion, and only in the downstream half.
Only two populations overlay with proven Federal oil and gas reserves,
Yellow and Rock Creeks (Table 4). The Rock Creek overlap is
insignificant, accounting for less than 1 percent of the population's
subwatershed. However, the Yellow
[[Page 63453]]
Creek overlap is sizable, at approximately a quarter of the
population's subwatershed. Correspondingly, only Yellow Creek has
measurable levels of current energy development at a moderate scale.
Because the impacts to Yellow Creek are downstream of a large portion
of the occupied area within the population boundary, we find oil and
gas development does not threaten the persistence of the Yellow Creek
population. Although some resource potential is found throughout the
range of the species, future development is unlikely to occur or impact
all but one population (Yellow Creek). Oil and gas development impacts
only a small portion of the species' total range, and the impacted
population will likely persist in upstream reaches. We found no
information that oil and gas development may act on this species to the
point that the species itself may be at risk, nor is it likely to
become so.
Mining
Hardrock mining for such materials as gold, copper, iron ore,
uranium, and others is the most common mining activity in the western
United States (Trout Unlimited 2011, p. 1). Underground and surface
mining activities have the potential to negatively affect fish species
by releasing solid wastes and contaminated mine water (Helfman 2007,
pp. 160-161; Trout Unlimited 2011, p. 1).
Solid waste from mining includes overburden, which is the topsoil
and surface rock that is above a mineral deposit; waste rock, which is
the low grade ore that surrounds a mineral deposit; and tailings, which
are the fine-grained materials that are left over from the processing
of raw ore (Trout Unlimited 2011, p. 1). Abandoned and currently
operating mine sites can impact downstream fish species from the
sedimentation that results from erosion of waste rock (Helfman 2007,
pp. 112, 113) (see Water Quality section for specific discussion of
sedmentation and northern leatherside chub).
Contaminated mine water is the ground or surface water that
accumulates and is discharged from a mine or its associated waste rock
piles (Trout Unlimited 2011, p. 1). This water can cause deleterious
effects to fishes via acidification and heavy metal contamination
(Helfman 2007, pp. 160-161, 168-169). Stream acidification results from
drainage of waters from mines or their waste rock by-products. This
water is highly toxic because the associated low pH harms fish
respiratory function and can impact reproduction rates and rearing
outcomes (Helfman 2007, p. 159). Low pH in aquatic systems also can
negatively affect aquatic plants and macroinvertebrates and thereby
reduce food sources and habitat for fish (Helfman 2007, pp. 160-161;
Trout Unlimited 2011, p. 1). Heavy metal contamination of aquatic
habitats also can result from mine water that is discharged from mines
or that infiltrates and then runs out of waste rock or tailings piles.
Heavy metals such as lead, copper, zinc, cadmium, mercury, aluminum,
iron, manganese, and selenium can be toxic to fishes at low
concentrations and can ultimately interfere with embryonic development,
digestion, respiration, general growth, and survival (Helfman 2007, pp.
160, 161; Trout Unlimited 2011, p. 1).
We assessed mining activity within the range of northern
leatherside chub by reviewing mining location data as reported by State
agencies and in GeoCommunicator, the publication Web site for the
National Integrated Land System as operated by a joint venture between
the BLM and USFS (https://www.Geocommunicator.gov/GeoComm, Mining
Claims). This information shows that uranium, coal, and non-coal (all
other mine types) were prospected for in much of the northern
leatherside chub range (Service 2011, pp. 25-32). However, the majority
of these mines or prospects are historical and are no longer in
operation (Service 2011, pp. 25-32).
In the Bear River subregion, there are no abandoned mines, active
mines, or mining claims in the Upper Mill/Deadman Creeks, Upper
Sulphur/La Chapelle Creeks, Yellow Creek, or Muddy Creek populations
(Service 2011, pp. 28, 30). In the Rock Creek drainage, there are 11
quarter sections with 1 to 5 mining claims each; however, these are
located downstream of northern leatherside chub occupied habitat and
are not being actively developed (Service 2011, p. 29). The Upper Twin
Creek population has one abandoned mine about 2 miles (mi) upstream of
occupied habitat on North Fork Twin Creek, and approximately four
abandoned mines upstream of occupied habitat on East Fork Twin Creek
(Service 2011, p. 29). Also, a small portion of the headwaters of the
Upper Twin Creek population is under an active coal lease; however, the
active mining associated with this lease is found on the other side of
the watershed boundary, meaning impacts will not affect northern
leatherside chub (WSGS 2009, map). We have no information to indicate
that any of these abandoned mines are having an effect on adjacent
northern leatherside chub in the Upper Twin Creek population. In the
Dry Fork Smiths Fork population, there are eight quarter sections with
one to five mining claims; however, these are located primarily
downstream of northern leatherside chub occupied habitat, are not
developed, and thus should not have an effect on occupied habitat
(Service 2011, p. 30).
In the Snake River subregion, there are no abandoned mines, active
mines, or mining claims within northern leatherside chub habitats in
the Trout or Jackknife Creek populations (Service 2011, pp. 25, 26).
The Trapper Creek and Beaverdam Creek populations have several
abandoned mines of lignite and uranium prospects/deposits that are
adjacent to northern leatherside chub occupied habitat (about four to
five sites in each drainage) (Service 2011, p. 25). Because prospects
and identified deposits usually involve a small disturbance such as a
shallow hole or a short adit (an entrance to an underground mine which
is horizontal or nearly horizontal), we determine these features are
having negligible impact on northern leatherside chub occupied habitat.
In the Pacific Creek population where northern leatherside chub are
found, there are 11 quarter sections with 1 to 5 mining claims each
(Service 2011, p. 27). These mining claims occur upstream of northern
leatherside chub occupied habitat; these claims are not developed, and
we have no information to suggest that these will be developed. At this
time we have no information to suggest that any of these abandoned
mines or mining claims are having a significant effect on adjacent
northern leatherside chub at an individual or population level.
In the Green River subregion, neither the Slate Creek nor the Upper
Hams Fork populations have abandoned mines, active mines, or mining
claims (Service 2011, pp. 31-32). Thus, there are no effects from
mining on northern leatherside chub populations in these areas.
In summary, recent examination of mining activity in northern
leatherside chub habitat has determined that mining-related impacts are
limited. Mining was historically prevalent in occupied portions of the
Bear and Snake subregions, but largely absent in occupied portions of
the Green River subregion. Some mines do still operate in northern
leatherside chub populations. However, we have no information at this
time to suggest that mining activities are having an effect on water
resources or habitat of northern leatherside chub. We found no
information that mining activities may act on this species to the point
that the
[[Page 63454]]
species itself may be at risk, nor is it likely to become so.
Water Development
Water development in western North America has the potential to
impact native fish species by degrading aquatic habitats and altering
natural ecological mechanisms (Minckley and Douglas 1991, p. 15; Naiman
et al. 2002, p. 455). Water development can affect aquatic species
through desiccation (drying that results in loss of habitat), reduction
in available habitat from reduced flows, reduced population
connectivity, and decreases in water quality (e.g., higher
