[Federal Register: April 6, 2010 (Volume 75, Number 65)]
[Proposed Rules]
[Page 17352-17363]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06ap10-22]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R1-ES-2009-0043]
[MO 92210-0-0008 B2]
Endangered and Threatened Wildlife and Plants; 12-month Finding
on a Petition To List the Mountain Whitefish in the Big Lost River,
Idaho, as Endangered or Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list the mountain whitefish
(Prosopium williamsoni) in the Big Lost River, Idaho, as endangered or
threatened under the Endangered Species Act of 1973, as amended. After
review of all available scientific and commercial information, we find
that the mountain whitefish in the Big Lost River does not constitute a
listable entity under the Act and, therefore, listing is not warranted.
However, we ask the public to continue to submit to us any new
information that becomes available concerning the taxonomy, biology,
ecology, and status of the mountain whitefish in the Big Lost River,
and to support cooperative conservation of mountain whitefish within
its historical range in the Big Lost River.
DATES: The finding announced in this document was made on April 6,
2010.
ADDRESSES: This finding is available on the Internet at http://
www.fws.gov/idaho, and also at http://www.regulations.gov at Docket No.
FWS-R1-ES-2009-0043. 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, Idaho Fish
and Wildlife Office, 1387 S. Vinnell Way, Room 368, Boise, ID 83709.
Please submit any new information, materials, comments, or questions
concerning this finding to the Service at this address.
FOR FURTHER INFORMATION CONTACT: Acting State Supervisor, Idaho Fish
and Wildlife Office (see ADDRESSES); by telephone at 208-378-5243; and
by facsimile at 208-378-5262. Persons who use a telecommunications
device for the deaf (TDD) may call the Federal Information Relay
Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (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 and commercial information
indicating that listing the species may be warranted, we make a finding
within 12 months of the date of receipt of the petition. In this 12-
month finding, we may determine that the petitioned action is either:
(1) Not warranted, (2) warranted, or (3) warranted, but 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 June 15, 2006, we received a petition from Western Watersheds
Project to emergency list as endangered or threatened the population of
mountain whitefish in the Big Lost River, Idaho, as a separate species,
subspecies, or distinct population segment (DPS) under the Act. The
petitioner also requested that we designate critical habitat concurrent
with the listing.
In an August 21, 2006, letter to the petitioner, we acknowledged
receipt of the petition and explained that we would not be able to
address the petition at that time due to other priorities relating to
court orders and settlement agreements. We further indicated we had
reviewed the petition and determined an emergency listing was not
necessary. On October 23, 2007,
[[Page 17353]]
we issued a 90-day finding (72 FR 59983), concluding the petition had
failed to provide substantial information indicating that listing the
Big Lost River population of mountain whitefish may be warranted, based
on a lack of information indicating it may be a listable entity under
the Act (a species, subspecies, or DPS). On January 25, 2008, Western
Watersheds Project filed a complaint challenging the negative 90-day
finding. On March 31, 2009, the United States District Court in Idaho
found that we had considered information beyond the material in the
petition in issuing the negative finding, such that we had effectively
begun to conduct a status review (Western Watersheds Project v. Dirk
Kempthorne, et al., Case No. CV07-409-S-EJL D. Idaho). The Court
directed us to proceed directly to a status review and, within 1 year,
issue a 12-month finding. We published a notice in the Federal Register
on August 6, 2009 (74 FR 39268) initiating the status review and
requesting new information for mountain whitefish in the Big Lost
River, Idaho. The 30-day comment and information period closed on
September 8, 2009. This notice constitutes the 12-month finding on the
June 14, 2006, petition to list the mountain whitefish in the Big Lost
River, Idaho, as endangered or threatened.
Species Information
Species Distribution and Habitat
Mountain whitefish are members of the family Salmonidae (broadly
termed ``salmonids'') and are found in rivers and lakes throughout
mountainous areas of western North America in Canada and the United
States (Figure 1). In the United States, they occur in the States of
Washington, Oregon, Idaho, Wyoming, Montana, Colorado, Utah, Nevada,
and California (NatureServe 2009). Mountain whitefish are relatively
common and widespread in most river basins in Idaho (AFS 2007, p. 29)
and, in general, occur in mainstem river reaches that are greater than
15 meters (m) (49.2 feet (ft)) wide and of low gradient (Maret et al.
1997, p. 213; Meyer et al. 2009, p. 763). Results of a study by Meyer
et al. (2009) assessing the environmental factors related to
distribution, abundance, and life history characteristics of mountain
whitefish in Idaho show mountain whitefish in southern Idaho are
abundant, long-lived, and fast growing (at warmer water temperatures)
until they reach sexual maturity. The authors also speculate that
mountain whitefish are relatively secure in the upper Snake River
basin, although little research has been done on the mountain whitefish
across the range of the species (Meyer et al. 2009, pp. 753, 765).
Although the majority of populations of mountain whitefish occur in
riverine environments, some populations are restricted to lakes or
isolated sink basins. Mountain whitefish in the Big Lost River reside
in a ``sink'' drainage, which was once part of a large Pleistocene lake
system that included Lake Terreton (Link 2003, in Van Kirk et al. 2003,
p. 6). As Lake Terreton waters receded, the Big Lost River and four
adjacent drainages lost their surface connection to the Snake River,
resulting in five isolated sink drainages in Idaho. It is estimated
mountain whitefish became isolated in the Big Lost River approximately
10,000 years ago (Behnke 2003, cited in Van Kirk et al. 2003, p. 8).
Other populations of mountain whitefish occur in other sink drainages,
such as tributaries in the Lahontan Basin in California and Nevada, and
the Bonneville Basin in Utah. Populations in these basins are similar
to the population in the Big Lost River in that all are relict
populations of mountain whitefish that formerly resided in large
Pleistocene lake systems that are now closed basins.
Distribution and Habitat Within the Big Lost River Basin
Mountain whitefish in the Big Lost River are physically isolated
from other whitefish populations within the Snake River basin. The Big
Lost River originates in the Pioneer, Boulder, Lost River, and White
Knob mountain ranges and flows down the Big Lost River Valley eastward
onto the Snake River Plain where it terminates at the Big Lost River
Sinks (Figure 2). Major tributaries include East Fork, Star Hope Creek,
Wildhorse Creek, North Fork, Thousand Springs Creek, Warm Springs
Creek, Alder Creek, Pass Creek, and Antelope Creek. Elevations in this
area range from 1,459 m (4,787 ft) at the Big Lost River Sinks to 3,859
m (12,661 ft) at the summit of Borah Peak. The climate of the drainage
is generally cool and dry. Annual precipitation along the valley floor
is about 20 centimeters (cm) (7.8 inches (in)), but increases to over
100 cm (39.4 in) at higher elevations. Vegetation within the basin
ranges from sagebrush steppe at lower elevations, to coniferous forests
at mid elevations, to alpine at higher elevations. The drainage is
comprised primarily of Federal land managed by the U.S. Forest Service
(USFS; 42 percent), Bureau of Land Management (BLM; 26 percent), and
Department of Energy (DOE; 15 percent), with lesser amounts of private
(14 percent) and State (2 percent) lands. The drainage is within
portions of Butte and Custer Counties and is sparsely populated, with
agriculture being the dominant land use on private lands. Primary uses
of Federal land include cattle grazing and recreation (IDFG 2007, p.
7). Historically, mountain whitefish occupied approximately 346.1
kilometers (km) (214 miles (mi)) of habitat in the Big Lost River
(Gamett 2009a, p. 5). Recent studies indicate mountain whitefish
currently occupy 134.8 km (86.3 mi) of the Big Lost River, with an
estimated population of 12,639 adult fish (Garren et al. 2009, pp. 5-
6). Although it is lower than suspected historical numbers, the current
population estimate shows an increase from surveys conducted between
2002 and 2005, when it was estimated that approximately 2,539 adult
mountain whitefish occupied 83.3 km (51.8 mi) of habitat in the Big
Lost River (Gamett et al. 2009, p. 5).
Species Description
Mountain whitefish can reach about 57 cm (22 in) in length at
maturity. The general body shape is slender with a somewhat round cross
section; body coloration is typically silver on the sides, dusky olive
green or blue on the back; and the belly is a dull white (Simpson and
Wallace 1982, p. 77). According to Gamett 2009 (personal observations
and unpublished data, pp. 8-9), mountain whitefish in the Big Lost
River can be distinguished from mountain whitefish in the nearby
Pahsimeroi River based on color. Whiteley (2007, pers. comm.) also
notes a color difference, and suggests that mountain whitefish in the
Big Lost River may also differ in head and body shape as well. None of
these suggested differences have been quantified or formally described,
however, and Gamett (2009, p. 9) notes the need for further research in
this regard.
Age of sexual maturity of mountain whitefish varies, with mountain
whitefish in southern Idaho documented to reach sexual maturity at 2 to
3 years (Meyer et al. 2009, p. 765), while fish from the Blacks Fork
River in Utah were reported to reach sexual maturity at 4 years for
males, and 5 to 7 years for females. The species is relatively long-
lived; one fish in Utah was aged at 12 years (Wydoski 2001, p. 694),
while the oldest fish recorded in the Meyer et al. study in Idaho was
estimated to be 24 years old (2009, p. 761). Mountain whitefish spawn
in the fall, and timing depends on stream temperatures (Simpson and
Wallace 1982, p. 77; Wydoski 2001, p. 694). Unlike other salmonids,
mountain whitefish are broadcast spawners,
[[Page 17354]]
meaning no nest or redd is created, and females scatter eggs and the
male fertilizes them (McGinnis 1984, p. 137). Spawning generally occurs
at night, with fish broadcasting their eggs and sperm in riffle areas
over clean gravel. Eggs incubate throughout the winter months, and
hatching typically occurs in March and April. Migrations associated
with spawning behavior appear to be highly variable across systems,
with some populations migrating into tributaries to spawn, while others
move very little (Northcote and Ennis 1994, p. 350). Upon hatching, fry
are thought to occupy lateral habitats and low velocity areas. Adult
habitat is variable, consisting of shallow riffles, moderate runs, and
deep pools during the summer, but primarily deeper pools in the winter
(Northcote and Ennis 1994, p. 353).
Mountain whitefish are thought to be opportunistic bottom feeders,
consuming whatever is in abundance, including fish eggs during the
spawning season (McGinnis 1984, p. 137). They are known to actively
feed on both aquatic and terrestrial insects, but may also eat other
small fish on occasion (NatureServe 2009).
Taxonomy
The mountain whitefish in the Big Lost River of Idaho are currently
recognized as members of the single species Prosopium williamsoni,
which is considered common and widespread throughout the mountainous
western United States northward into Canada (Nelson et al. 2004, p. 86;
ITIS 2009; NatureServe 2009). Although the State of Idaho does not
consider the mountain whitefish occupying the Big Lost River to be
either a significant species or a species of concern, they have
developed a management plan specific to this population of mountain
whitefish (IDFG 2007, pp. 1-32).
Defining a Species Under the Endangered Species Act
Our first step in making a 12-month finding is to establish that
the subject under consideration constitutes a ``species'' as defined
under section 3(16) of the Act. Section 3(16) defines ``species'' to
include ``any subspecies of fish or wildlife or plants, and any
distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature'' (16 U.S.C. 1532(16)). Our
implementing regulations at 50 CFR 424.11 provide further guidance for
determining whether a species (as defined in the Act and our
regulations at 50 CFR 424.02(k)) is eligible for listing under the Act:
``In determining whether a particular taxon or population is a species
for the purposes of the Act, the Secretary shall rely on standard
taxonomic distinctions and the biological expertise of the Department
and the scientific community concerning the relevant taxonomic group''
(50 CFR 424.11(a)).
As previously discussed, mountain whitefish in the Big Lost River
are classified taxonomically as Prosopium williamsoni, the same as
other mountain whitefish across the range of the species. Before
proceeding further, we must first determine whether the mountain
whitefish in the Big Lost River are a separate species, subspecies, or
DPS, and thus constitute a potentially listable entity under the Act.
Evaluation of Mountain Whitefish in the Big Lost River as a Species or
Subspecies
The petitioner asked us to list the population of mountain
whitefish in the Big Lost River, Idaho, as a separate species,
subspecies, or DPS. As discussed in the ``Taxonomy'' section above,
mountain whitefish in the Big Lost River of Idaho are currently
recognized as members of the single species Prosopium williamsoni,
which is considered common and widespread throughout the mountainous
western United States northward into Canada (NatureServe 2009). The
American Fisheries Society and the American Society of Ichthyologists
and Herpetologists, the scientific authorities with regard to this
taxonomic group, do not recognize mountain whitefish in the Big Lost
River as a separate species or subspecies (Nelson et al. 2004, p. 86).
The Integrated Taxonomic Information System, a database maintained by a
partnership of Federal agencies to provide scientifically credible
taxonomic information, similarly does not recognize mountain whitefish
in the Big Lost River as a separate species or subspecies (ITIS 2009).
Thus, per our implementing regulations at 50 CFR 424.11, standard
taxonomic distinctions and the biological expertise of the scientific
community concerning the relevant taxonomic group, the mountain
whitefish in the Big Lost River are not recognized as a separate
species or subspecies of mountain whitefish.
The petitioner, however, maintained the mountain whitefish in the
Big Lost River should be protected as a separate species or subspecies
of whitefish ``because all genetic analyses demonstrate that it is
genetically unique--so much so that the genetic distance observed
between Big Lost River mountain whitefish and surrounding populations
is at least as large as that seen between other subspecies or even
species.'' We carefully evaluated the petitioner's assertion, which
relies primarily on the analysis of molecular genetic data. Because of
the complex and highly technical nature of molecular analysis, we
consulted with a fisheries genetics expert within the Service to assess
the potential significance of the genetics information available to us
regarding mountain whitefish in the Big Lost River. Dr. Donald E.
Campton, Senior Science Advisor for the U.S. Fish and Wildlife
Service's Pacific Region Fisheries Resources Division, and former
President of the Genetics Section of the American Fisheries Society,
served as our expert on this finding.
No universally accepted definition of species or subspecies exists.
In general such classifications are based on multiple lines of evidence
that are consistent with the hypothesis that the entity in question is
a separate species or subspecies, including factors such as morphology,
physiology, behavior, and genetic characteristics (Haig et al. 2006, p.
1586). In reviewing an entity as a potential species or subspecies, we
consider as many lines of available, reliable evidence as possible.
Particularly, in the case of an entity that is being proposed as a new
taxonomic treatment and that has not been recognized as such by the
relevant scientific community, we bring our biological expertise to
bear and require multiple lines of persuasive and credible
corroborating evidence to support any such change, in accordance with
our regulations at 50 CFR 424.11(a).
Information on the genetics of mountain whitefish in the Big Lost
River of Idaho is available from several recent publications, including
Whiteley et al. (2006), Campbell and Kozfkay (2006), and Miller (2006).
In Whiteley et al. (2006), the researchers utilized both allozymes and
microsatellites to examine the genetic structure of mountain whitefish
populations throughout the northwestern United States and British
Columbia, plus two populations from western Alberta. Allozymes are
forms of enzymes coded for by different alleles at the same genetic
locus, and can be distinguished by electrophoresis; microsatellites are
repeating sequences of base pairs in the DNA, and are typically used as
highly variable genetic markers. Whiteley et al. (2006, p. 2778) found
that mountain whitefish in this region (all representatives of the
species Prosopium williamsoni), form three large-scale genetic
assemblages based on allozyme data and five large-scale genetic
assemblages based on
[[Page 17355]]
microsatellite data. The Big Lost River population was included within
the resulting Upper Snake River assemblage (Upper Snake) in both
scenarios, and is described as the ``most genetically divergent'' site
in that assemblage. While this is an accurate characterization,
examination of the data demonstrates that the degree of genetic
divergence of mountain whitefish in the Big Lost River from other
populations in the Upper Snake genetic assemblage largely reflects the
absence of within-population genetic variation in individuals from the
Big Lost River and is less than the genetic divergence observed between
the Upper Snake and other major assemblages of mountain whitefish
(Whiteley et al. 2006, Table 1, pp. 2770-2771). In other words, the
mountain whitefish in the Big Lost River appear to be divergent largely
as a result of the lack of genetic diversity exhibited by this
population relative to other populations, not as the result of any
unique genetic characteristics. Although the most divergent group
within the Upper Snake, Whiteley et al. (2006, pp. 2775-2776) found the
Big Lost River population still clustered within that major genetic
assemblage.
This result is consistent with that reported by another researcher
in her study of mitochondrial DNA in mountain whitefish, detailed
further below. Miller (2006, p. 30) concludes ``the Big Lost River
mountain whitefish still group with other populations from the upper
Snake River Sub-basin.'' These results do not suggest that mountain
whitefish in the Big Lost River stand out from among all populations of
mountain whitefish examined as genetically unique or differentiated to
the point that they would be considered a separate species or
subspecies. If that were the case, then one would expect the Big Lost
River mountain whitefish's level of divergence to be greater than the
level of divergence observed between the major genetic groupings, and
they would not cluster within a major genetic assemblage.
The analysis of Whiteley et al. (2006) shows mountain whitefish
populations that are geographically isolated are relatively more
distinctive genetically than populations that may experience gene flow
between them. Although Whiteley et al. (2006, p. 2780) reported little
evidence of differentiation among sites within major river basins in
general, they note that the Upper Snake (which includes the Big Lost
River) and Olympic Peninsula were an exception to this rule, due to the
natural restrictions on gene flow in these areas. Whiteley et al.
(2006, p. 2780) identified low levels of within-population genetic
variation (relatively lower levels of genetic diversity) in several
physically-isolated populations of mountain whitefish, including not
only the Big Lost River, but also the Big Wood River, Bull River, and
Thutade Lake. They also noted a higher degree of genetic
differentiation in several physically-isolated sites in the region
associated with the Upper Snake River assemblage; in addition to the
Big Lost River, this pattern was observed at the Henry's Fork and
several Bonneville Basin sites (Whiteley et al. 2006, p. 2781).
Such results are not unexpected; in fact, this condition is exactly
what would be predicted by basic conservation genetics theory for
small, isolated populations (Meffe and Carroll 1994, pp. 156-158).
These isolated populations are relatively genetically divergent
compared to other populations that experience higher levels of gene
flow (gene flow or genetic mixing maintains greater levels of genetic
diversity or heterogeneity in the population). Such a level of
differentiation does not necessarily suggest a subspecies or species-
level difference; nor does the ability to detect genetic differences
between populations necessarily equate to meaningful biological
significance (Hedrick 1999, pp. 316-317). Fish in general, and
particularly freshwater salmonids, tend to exhibit a high degree of
genetic structuring (Allendorf and Waples 1996, p. 257; Whiteley et al.
2006, p. 2783), such that it is not unusual to be able to easily
distinguish between populations of the same species based on molecular
genetic differences. Yet, if one were to rely solely on the ability to
distinguish between fish populations based on genetic differences to
identify new subspecies or species, as Haig et al. (2006, p. 5, citing
Mayden 1999) noted, ``every isolated creek and pond could have a unique
subspecies or species of fish.'' This ability to so finely subdivide
species based purely on the ability for genetic discrimination between
them has led the Service, as described above, to require a more
holistic approach to species or subspecies analysis that builds upon
multiple lines of evidence, including, where possible, a full suite of
morphological, physiological, behavioral, and genetic characteristics,
to support a formerly unrecognized taxonomic distinction.
The analysis of the genetic relationships of mountain whitefish by
Whiteley et al. 2006 does not support the contention that mountain
whitefish of the Big Lost River are distinctive or unique genetically
when compared to other populations in the Upper Snake River assemblage,
or when compared to populations within other assemblages of the
species. Rather, the authors point to a high degree of genetic
differentiation between many populations of mountain whitefish in the
Upper Snake due to the topography of the region, and characterize those
populations as ``more finely subdivided than elsewhere'' (Whiteley et
al. 2006, p. 2781). The authors also point out that the degree of
genetic differentiation observed in mountain whitefish among
tributaries within river basins is less than that observed in
populations of other salmonids, such as bull trout (Salvelinus
confluentus) and westslope cutthroat trout (Oncorhynchus clarki lewisi)
(i.e., bull trout and westslope cutthroat trout show greater levels of
genetic differentiation between populations within river basins than do
mountain whitefish) (Whiteley et al. 2006, p. 2783). Despite this high
degree of genetic structuring, it has not been suggested that each
individual bull trout or westslope cutthroat trout population be
considered as a separate species or subspecies; each genetically
differentiable population of bull trout and westslope cutthroat trout
is still considered a member of the broader taxon (species or
subspecies, respectively). If the mountain whitefish in the Big Lost
River were a separate species or subspecies, based on genetic
characteristics, one would expect mountain whitefish in the Big Lost
River to exhibit greater genetic differentiation than populations of
salmonids that are considered members of the same species or
subspecies, not less.
Campbell and Kofzkay (2006) used mitochondrial DNA to assess
mountain whitefish populations in Idaho, Utah, and Montana, and also
specifically to evaluate the origin and divergence of mountain
whitefish in the Big Lost River. Their results support the three major
genetic assemblages identified by Whiteley et al. (2006), which
Campbell and Kofzkay (2006, p. 6) describe as the Upper Snake River
drainage (upstream of Shoshone Falls) and the Bonneville basin; the
Lower Snake River drainage (downstream of Shoshone Falls) including the
Pahsimeroi and Salmon Rivers; and the Upper Missouri River. The authors
note the pairwise divergence estimates between these major genetic
assemblages of mountain whitefish were very high, ranging from 1.31 to
4.56 percent (Campbell and Kofzkay 2006, p. 7). For comparison
purposes, they point out that estimates of mitochondrial DNA sequence
divergence between two salmonid
[[Page 17356]]
subspecies, the westslope cutthroat trout and Yellowstone cutthroat
trout (Oncorhynchus clarkia bouvieri), range from 1.5 to 1.9 percent
(Gyllensten and Wilson 1987, IDGF unpublished data, cited in Campbell
and Kofzkay 2006, p. 7). The divergence between the large major
assemblages of mountain whitefish may thus be similar to the degree of
divergence between recognized subspecies of cutthroat trout.
However, pairwise divergence estimates for mountain whitefish in
the Big Lost River are solidly within the range of normal divergence
for populations of whitefish within the Upper Snake River assemblage
(Campbell and Kofzkay 2006, Figure 3, p. 8). The percent sequence
divergence of mountain whitefish from the Big Lost River compared to
other populations within the Upper Snake River Basin ranges from 0.33
to 0.49 percent. The levels of sequence divergence between subspecies
of cutthroat trout (1.4 to 1.9 percent) and between different species
of trout (rainbow trout (O. mykiss) and cutthroat trout (4.0 to 4.5
percent) (Campbell and Kozfkay 2006, p. 7) are far higher than that
observed between mountain whitefish in the Big Lost River and other
populations within the Upper Snake River assemblage (Campbell and
Kofzkay 2006, p. 8). According to this study, the genetic distance
between mountain whitefish in the Big Lost River and surrounding
populations is far less than that observed between these subspecies or
species of salmonids. Furthermore, several other populations of
mountain whitefish examined by Campbell and Kofzkay (2006, Figure 3, p.
8) exhibited greater levels of divergence from other populations within
their assemblage than that exhibited by fish from the Big Lost River
(the Boise River populations in the lower Snake River assemblage, for
example). Thus, the data of Campbell and Kofzkay (2006) indicate the
mountain whitefish in the Big Lost River are not particularly
distinctive or unusual in terms of genetic divergence, when compared to
other populations of mountain whitefish throughout the range of the
species.
Miller (2006) examined the phylogeography of the genus Prosopium in
western North America, analyzing mitochondrial DNA using the cytochrome
b (cytb) and NADH dehyrogenase subunit 2 (ND2) sequences. This analysis
included the mountain whitefish P. williamsoni, and three taxa found
only in Bear Lake on the Utah-Idaho border: the Bear Lake whitefish (P.
abyssicola), the Bonneville whitefish (P. spilonotus), and the
Bonneville cisco (P. gemmifer). Similar to the other researchers,
Miller reported a high amount of genetic structure for mountain
whitefish based on drainage basins or sub-basins. Analyses of molecular
variance demonstrated between 62.5 and 75.8 percent of the total
genetic variation was found between drainage basins or subbasins
(Miller 2006, p. 22). Miller's analysis found evidence for multiple
populations of mountain whitefish that are geographically isolated and
demonstrate little to no gene flow, including populations in the Hoh
River, Duchesne River, Big Wood River, Big Lost River, and Coeur
d'Alene River (Miller 2006, pp. 22-23).
The nested clade analysis conducted by Miller resulted in somewhat
different results for the cytb and ND2 sequences. Analysis based on
cytb resulted in the identification of four major clades of Prosopium:
(1) A Missouri River basin clade; (2) a Bear Lake Prosopium clade; (3)
a Columbia River subbasin/lower Snake River subbasin/Lahontan Basin
clade; and (4) a Bonneville basin/upper Snake River subbasin/Green
River basin/Bear Lake Prosopium clade (Miller 2006, p. 23). Analysis
based on ND2 resulted in two major clades: (1) A Columbia River
subbasin/lower Snake River subbasin/Lahontan basin clade, and (2) a
Bonneville Basin/upper Snake River subbasin/Green River basin/Missouri
River basin/Bear Lake Prosopium clade (Miller 2006, p. 23), with the
Big Lost River and Missouri River populations representing two
divergent subgroups within this latter clade (Miller 2006, Figs. 16a,
pp. 130-137, and 16c, pp. 146-149). For both cytb and ND2, she found
the haplotypes for the Big Lost River (upper Snake River subbasin), the
Big Wood River (lower Snake River subbasin), and the Hoh River
(Columbia River subbasin) formed isolated clades (included only
haplotypes from their own system, and did not contain haplotypes from
outside of their clades) (Miller 2006, p. 24). Miller concluded that
these three populations are genetically distinct from other populations
within their basins due to their relative isolation. With regard to the
Big Lost River population in particular, however, she concludes,
``Although distinct from other upper Snake River populations, the Big
Lost River mountain whitefish still group with other populations from
the upper Snake River Sub-basin'' (Miller 2006, p. 30). This result is
consistent with that of Whiteley et al. 2006 (p. 2778); the mountain
whitefish in the Big Lost River are genetically distinctive within
their major genetic assemblage, but do not stand out from all other
populations when considered in the context of the species across its
range.
The petitioner offered additional information in support of the
contention that mountain whitefish in the Big Lost River represent a
separate species or subspecies; that additional information was a
reference to an abstract from an oral presentation made at a meeting of
the Idaho Chapter of the American Fisheries Society (Van Kirk et al.
2003, p. 13). This abstract, authored by Whiteley and Gamett, refers to
``the fixation of a unique allele in the Big Lost River population at
one of the microsatellite loci.'' Data to support this statement were
not available to us. If we assume that one microsatellite allele has
become fixed in mountain whitefish occupying the Big Lost River, that
information does not by itself confer any meaningful genetic
significance or biological or ecological importance (e.g., as measured
by morphological, physiological, or behavioral traits) because
microsatellite alleles are considered selectively neutral, the
frequencies of which largely reflect random or stochastic processes
(e.g., genetic drift, population bottlenecks, founder effects, mutation
rates), rather than selection for traits that confer increased fitness
(Ashley and Dow 1994, p. 185). Indeed, the total lack of variability
observed in microsatellites sampled for mountain whitefish in the Big
Lost River (Whiteley et al. 2006, p. 2775) indicates that this
population has likely undergone a past population bottleneck relative
to other populations, with a subsequent loss of genetic variability and
random fixation (e.g., via drift of a unique [or nearly unique] allele)
(D. Campton, pers. comm. 2007).
This conclusion is also supported by the work of Miller, who
concludes the mountain whitefish in the Big Lost River experienced
restricted gene flow (2006, p. 25). Under such conditions, genetic
distance may increase quickly, but is not in and of itself indicative
of biological significance (Hedrick 1999, pp. 315-316). Genetic
isolation and a relatively small population size would predictably lead
to the loss of haplotypes that might otherwise be shared with other
populations, leading to the ability to distinguish a population as
``different.'' In other words, it is technically possible to
differentiate between two such populations on the basis of their
genetic characteristics. However, this purely technical ability for
genetic discrimination between populations does not necessarily
represent any biological or ecological importance. We have no
information to indicate that the fixation of any single microsatellite
allele in mountain
[[Page 17357]]
whitefish in the Big Lost River may, in any way, be biologically
important or significant to the taxon as a whole. Such fixed allelic
differences between geographically isolated freshwater populations of
salmonid fishes are not considered uncommon (Allendorf and Waples 1996,
p. 257). Although these allelic differences may allow for the detection
of statistically significant differences between populations, and hence
the ability to discriminate between them on the basis of their genetic
characteristics, as Hedrick (1999, p. 317) notes, the connection
between biological and statistical significance may often be weak, and
great care must be taken in interpreting statistical significance as
the equivalent of biologically meaningful significance.
Mountain whitefish in the Big Lost River do possess unique
mitochondrial DNA haplotypes, but the same is true of almost every
other mountain whitefish population sampled by Campbell and Kofzkay
(2006, Table 1, p. 6) and Miller (2006, Table 3, pp. 51-56, and Table
4, pp. 57-63). The majority of surveyed mountain whitefish populations
had unique mitochondrial DNA haplotypes, as does the population in the
Big Lost River, and some populations had several. The possession of a
population-specific haplotype is, therefore, not unique to the mountain
whitefish in the Big Lost River. In addition, the genetic divergence of
mountain whitefish in the Big Lost River is not necessarily greater
than that observed in other populations. For example, based on the data
of Campbell and Kofzkay (2006, Figure 3, p. 8) and Miller (2006, Figure
16, pp. 130-157), the divergence among haplotypes between fish in the
Big Lost River and other populations in the Upper Snake River is
approximately three times less than the degree of divergence observed
among individual mountain whitefish collected from a single population
in the Boise River.
In our review of the best available information regarding the
degree of genetic divergence of mountain whitefish in the Big Lost
River relative to other populations of whitefish, we have determined
that many - if not most - populations of mountain whitefish sampled by
Campbell and Kozfkay (2006, p. 6) and Miller (2006, pp. 51-63) can be
said to be genetically different relative to other populations of the
species. Most mitochondrial DNA haplotypes occur in only one population
and are not shared between populations, clearly indicating the lack of
gene flow among most populations (Campbell and Kofzkay 2006, Table 1,
p. 6; Miller 2006, Table 3, pp. 51-56, and Table 4, pp. 57-63). In
addition, substantially greater mitochondrial DNA nucleotide diversity
exists among individual fish within some populations of mountain
whitefish, than exists between mountain whitefish in the Big Lost River
and other populations in the Upper Snake River (Campbell and Kofzkay
2006, Figure 3, p. 8; Miller 2006, Figure 16, pp. 130-157). Genetic
analyses by both Whiteley et al. (2006, pp. 2775-2776) and Miller
(2006, p. 30) determined that mountain whitefish in the Big Lost River
cluster within the Upper Snake genetic subgroup of Prosopium
williamsoni. Based on the best available scientific information, we
conclude the evidence is not sufficient to support recognition of the
mountain whitefish in the Big Lost River as a separate species or
subspecies based on the genetic characteristics of the population
relative to all other populations of the species P. williamsoni.
As we noted earlier, in evaluating whether an entity may
potentially represent a heretofore unrecognized species or subspecies,
it is important to consider multiple lines of evidence. Haig et al.
(2006, p. 8) argue that higher levels of confidence can be obtained in
classifications based on the concurrence of multiple morphological,
molecular, ecological, behavioral, and physiological characters. We
therefore considered whether any other characteristics of mountain
whitefish in the Big Lost River offer any credible support for the
argument that they may be a separate species or subspecies.
The information available to us suggests mountain whitefish in the
Big Lost River may exhibit differences in coloration or morphology.
This suggestion is based on the personal observations of two
researchers, Andrew Whiteley and Bart Gamett. Dr. Whiteley suggested
that mountain whitefish from the Big Lost River may differ in color and
form, possibly having shorter heads and a different body shape, but
stated that these traits have not been quantified and were based only
on his personal observations (A. Whiteley 2007a, pers. comm.). Mr.
Gamett (2009b, pp. 8-9) also noted that mountain whitefish from the Big
Lost River can be readily distinguished from specimens of mountain
whitefish found in other drainages (e.g., Pahsimeroi River) based on
color; however, this has not been formally described, and is based on
personal opinion. Gamett (2009b, p. 9) noted that further research is
needed to address this question.
Although mountain whitefish in the Big Lost River may possibly look
different, we have no evidence before us to suggest that any
differences in color or morphology that may exist are anything other
than natural phenotypic variation that is often observed in different
populations of fish. Natural variation in characteristics such as body
shape in fish is commonly attributable to environmental factors, such
as water temperature during development (e.g., Barlow 1961, pp. 105-
106). Additionally, many fish exhibit a considerable degree of
intraspecific (within the species) variation in morphology, which has
been experimentally demonstrated to be the result of phenotypic
plasticity in response to the environment, rather than a heritable
response to selection (e.g., Mittelbach et al. 1999, pp. 111, 126).
Head depth is a common plastic trait in fish related to diet (e.g., Day
et al. 1994, pp. 1723, 1730). We have no information to suggest that
any apparent differences in morphology or coloration of the mountain
whitefish in the Big Lost River, which have never been quantified or
formally described, are in any way biologically meaningful such that
they might represent possible differentiation to the degree that
subspecies or species recognition might be warranted--that is, whether
they might possibly be associated with some fitness advantage or
adaptation specific to this population, as opposed to simple local
variation in phenotypic traits.
It has been suggested that the mountain whitefish in the Big Lost
River are more genetically divergent than currently recognized species
of Prosopium endemic to Bear Lake (Whiteley 2007b, pers. comm.). In her
examination of the three species of Prosopium endemic to Bear Lake (P.
abyssicola, P. gemmifer, and P. spilonotus), Miller (2006, pp. 31-32)
found the mitochondrial DNA data failed to break into discrete clades
of their respective species, possibly indicative of ongoing adaptive
radiation (i.e., they are still undergoing the process of speciation),
ongoing hybridization, or other factors. In this case, although the
genetic information does not provide a clear distinction between these
three groups, other multiple lines of evidence potentially support the
taxonomic distinction between these species, including differences in
spawning times, scale counts, and morphology (Miller 2006 and
references therein, pp. 2-3, 34). Miller notes that although the three
Bear Lake species are not genetically differentiable, the
``morphological, ecological, and behavioral differences are real''
(Miller 2006, p. 32). However, she also points out that this lack of
congruence with the genetic information
[[Page 17358]]
does raise some questions regarding the current classification of these
species (Miller 2006, p. 35), further reinforcing the point that
stronger taxonomic distinctions can be made based on multiple lines of
consistent supporting evidence.
By contrast, although mountain whitefish in the Big Lost River may
show a greater degree of genetic differentiation from other groups than
that observed in the Bear Lake Prosopium, we note that any potentially
corroborating morphological, ecological, behavioral, or physiological
characteristics that might serve as supporting evidence of meaningful
phenotypic divergence, such as that used in identifying the three
species of Bear Lake Prosopium, are lacking for mountain whitefish in
the Big Lost River. Most populations of mountain whitefish exhibit a
high degree of geographical genetic differentiation throughout their
range (Campbell and Kofzkay 2006, Figure 3, p. 8; Whiteley et al. 2006,
p. 2781), and several of them show a greater degree of genetic
differentiation than that exhibited between the three species of Bear
Lake Prosopium (Miller 2006, Figure 16, pp. 130-157). However, in the
absence of any reliable corresponding evidence indicative of local
adaptation or phenotypic divergence, we believe there is insufficient
support for the recognition of any such population as a new species or
subspecies based on this genetic information. Thus we do not find the
greater genetic divergence observed in mountain whitefish in the Big
Lost River relative to that observed between the Bear Lake Prosopium
persuasive evidence that mountain whitefish in the Big Lost River
should be considered a species or subspecies.
In summary, mountain whitefish occurring in the Big Lost River are
not currently recognized by the relevant taxonomic authorities as a
species or subspecies (Nelson et al. 2004, p. 86; ITIS 2009;
NatureServe 2009), and our evaluation of the best available scientific
and commercial data does not indicate that mountain whitefish in the
Big Lost River represent a distinct species or subspecies relative to
other populations of Prosopium williamsoni. Available evidence
indicates there is a high degree of genetic structuring between many
populations of mountain whitefish, and particularly those in the Upper
Snake, as is frequently observed between populations of other
freshwater salmonids (Allendorf and Waples 1996, p. 257; Miller 2006,
p. 25; Whiteley et al. 2006, pp. 2781, 2783). Modern molecular
techniques allow virtually every population to be distinguished from
one another, and almost every population of mountain whitefish surveyed
had at least one unique haplotype. Thus every population of mountain
whitefish sampled so far could be considered genetically ``distinct,''
including the mountain whitefish in the Big Lost River. As explained
above, however, the genetic data before us do not indicate that the
mountain whitefish in the Big Lost River are biologically unique or
unusual compared to other populations of the species, so as to warrant
consideration as a separate species or subspecies.
Furthermore, in reviewing all available information, we found no
substantiated evidence of ecological, morphological, physiological,
behavioral, or other characteristics that would indicate any adaptive
divergence or patterns of adaptation have taken place in mountain
whitefish occurring in the Big Lost River, and that might be considered
additional evidence of a potentially distinct species or subspecies. We
therefore conclude, based on all of the best available scientific and
commercial data, that consideration of mountain whitefish in the Big
Lost River as a separate species or subspecies is not warranted at this
time.
Evaluation of Mountain Whitefish in the Big Lost River as a Distinct
Population Segment
To interpret and implement the distinct vertebrate population
segment (DPS) provisions of the Act and Congressional guidance, we, in
conjunction with the National Marine Fisheries Service (now the
National Oceanic and Atmospheric Administration--Fisheries), published
the Policy Regarding the Recognition of Distinct Vertebrate Population
Segments (DPS Policy) in the Federal Register on February 7, 1996 (61
FR 4722). Under the DPS policy, two basic elements are considered in
the decision regarding the establishment of a population of a
vertebrate species as a possible DPS. We must first determine whether
the population qualifies as a DPS; this requires a finding that the
population is both: (1) Discrete in relation to the remainder of the
species to which it belongs; and (2) biologically and ecologically
significant to the species to which it belongs. If the population meets
the first two criteria under the DPS policy, we then proceed to the
third element in the process, which is to evaluate the population
segment's conservation status in relation to the Act's standards for
listing as an endangered or threatened species. These three elements
are applied similarly for additions to or removals from the Federal
Lists of Endangered and Threatened Wildlife and Plants.
In accordance with our DPS Policy, we detail our analysis of
whether a vertebrate population segment under consideration for listing
may qualify as a DPS. As described above, we first evaluate the
population segment's discreteness from the remainder of the species to
which it belongs. Under the DPS policy, a population segment of a
vertebrate taxon may be considered discrete if it satisfies either one
of the following conditions:
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries
within which differences in control of exploitation, management of
habitat, conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act.
If we determine that a vertebrate population segment is discrete
under one or more of the conditions described in the Service's DPS
policy, we then consider its biological and ecological significance to
the larger taxon to which it belongs, in light of Congressional
guidance (see Senate Report 151, 96th Congress, 1st Session) that the
authority to list DPSes be used ``sparingly'' while encouraging the
conservation of genetic diversity. In making this determination, we
consider available scientific evidence of the discrete population
segment's importance to the taxon to which it belongs. Since precise
circumstances are likely to vary considerably from case to case, the
DPS policy does not describe all the classes of information that might
be used in determining the biological and ecological importance of a
discrete population. However, the DPS policy describes four possible
classes of information that provide evidence of a population segment's
biological and ecological importance to the taxon to which it belongs.
As specified in the DPS policy (61 FR 4722), this consideration of the
population segment's significance may include, but is not limited to,
the following:
(1) Persistence of the discrete population segment in an ecological
setting unusual or unique to the taxon;
(2) Evidence that loss of the discrete population segment would
result in a significant gap in the range of a taxon;
(3) Evidence that the discrete population segment represents the
only
[[Page 17359]]
surviving natural occurrence of a taxon that may be more abundant
elsewhere as an introduced population outside its historic range; or
(4) Evidence that the discrete population segment differs markedly
from other populations of the species in its genetic characteristics.
A population segment needs to satisfy only one of these conditions
to be considered significant. Furthermore, other information may be
used as appropriate to provide evidence for significance.
Discreteness
Our DPS policy states that a population segment of a vertebrate
species may be considered discrete if it is markedly separated from
other populations of the same taxon as a consequence of physical,
physiological, ecological, or behavioral factors. We find that mountain
whitefish in the Big Lost River are discrete, since they occur in a
closed basin lacking a surface connection to any major river system,
and are therefore physically separated from the remainder of the
populations in the taxon. We therefore conclude that mountain whitefish
in the Big Lost River satisfy the discreteness criterion of the DPS
policy.
Significance
Having determined that mountain whitefish in the Big Lost River
meet the discreteness criterion, our DPS policy directs us to next
consider available scientific evidence of the biological and ecological
importance of this discrete population to the remainder of the species
to which it belongs. In this case, we evaluate the biological and
ecological significance of the mountain whitefish in the Big Lost River
relative to mountain whitefish throughout the remainder of their range
in the western United States and Canada. A discrete population is
considered significant under the DPS policy if it meets one of four of
the elements identified in the policy under significance, or can
otherwise be reasonably justified as being significant. Here we
evaluate the four potential factors suggested by our DPS policy in
evaluating significance.
(1) Persistence of the Discrete Population Segment in an Ecological
Setting Unusual or Unique to the Taxon
Mountain whitefish in the Big Lost River are found in a closed
surface drainage basin. However, as noted earlier, mountain whitefish
also occur in isolated populations in sink drainages in the Bonneville
Basin in Utah and the Lahontan Basin in California and Nevada. In
addition, mountain whitefish also occur in other geographically
isolated settings, such as above barrier waterfalls (e.g., Big Wood
River, Bull River, Thutade Lake, Henry's Fork; Whiteley et al. 2006,
pp. 2780-2781) or above saltwater barriers to dispersal, as on the
Olympic Peninsula (Whiteley et al. 2006, p. 2781). Therefore, the mere
fact that these mountain whitefish occupy a physically isolated
drainage is not in and of itself unique, unusual, or significant to the
species as a whole. Although we acknowledge that Miller (2006, p. 29)
describes the Big Lost River as the most unique drainage of the upper
Snake River subbasin due to its geological history, we note that this
reference is comparing the drainage only within the context of the
subbasin in which it occurs, and not to the entire range of mountain
whitefish. Miller (2006, p. 2) points out that members of the genus
Prosopium in western North America ``occupy discrete drainage basins
most of which have complex geological histories.'' Residence in a
discrete drainage basin with a complex geological history therefore
appears to be a general characteristic of the genus.
We have no information indicating that the geological history of
the Big Lost River drainage, even if considered unique or unusual, has
in any way contributed to a unique or unusual ecological setting, such
that the whitefish occurring therein are biologically or ecologically
significant to the species as a whole. As noted above, there are other
populations of mountain whitefish in closed ``sink'' drainages within
the range of the species. We have no information indicating that the
Big Lost River drainage is ecologically unusual or unique in any other
way (for example, in terms of unique or unusual prey species, community
composition, water chemistry, pathogens, or substrate), apart from its
geographic setting, that may serve as an indicator of the biological or
ecological importance of the population of mountain whitefish found
there in relation to the species as a whole. The one exception is a
suggestion that the Big Lost River may be ecologically unusual because
historically it lacked other large fish species, such as trout; we
discuss this suggestion below.
Gamett (2009b, p. 8) suggests that the Big Lost River may be
unusual due to the fact that other than mountain whitefish, the only
other large fish native to the river are sculpin, and all other
mountain whitefish have evolved in the presence of other large fish
such as trout and suckers. He states that all other fish species,
including several species of trout, were not introduced into the Big
Lost River until the arrival of the first permanent settlers in the
late 1800s (Gamett 2009a, pp. 1, 8). We carefully considered the
potential ecological or biological significance of this information. If
there were some evidence that in the absence of trout or other large
fish, mountain whitefish in the Big Lost River had somehow become
specialized or otherwise adapted to this particular ecological
condition in a way that set them apart from the remainder of the
species, this may be of potential biological or ecological importance.
There is no information to suggest that mountain whitefish in the Big
Lost River became specialized or adapted in this manner. Several
species of trout were introduced to the Big Lost River more than 100
years ago, with no apparent effect--behavioral, morphological, or
otherwise--on the mountain whitefish population. Mountain whitefish in
the Big Lost River have shown none of the responses typical of a native
species responding to an unfamiliar invasive species, such as niche
displacement or competitive exclusion (Mooney and Cleland 2001, pp.
5446-5451).
We found no information to suggest that mountain whitefish in the
Big Lost River had become so specialized following their isolation from
the remainder of the taxon that they are now incapable of coexisting
with trout. Studies have shown no evidence of competition between
nonnative fish and mountain whitefish, and it is considered unlikely
that competition has negatively affected mountain whitefish in the Big
Lost River, since declines in this mountain whitefish population were
only reported relatively recently, and were not observed subsequent to
the introduction of trout over 100 years ago (IDFG 2007a, p. 22).
Therefore, although the information that mountain whitefish in the Big
Lost River were isolated from trout and other potentially predatory or
competitive fishes up until approximately 100 years ago is possibly of
some biological interest, we have no evidence that it represents any
ecological significance of the setting, or has resulted in any unique
or unusual adaptations or trait shifts in the mountain whitefish, such
that the population of mountain whitefish in the Big Lost River would
be considered biologically or ecologically significant to the species
throughout its range.
On the basis of an evaluation of the best available scientific
information, we have determined that the Big Lost River does not
represent an ecological setting that is unusual or unique for mountain
whitefish relative to the taxon's range in western North America. Other
[[Page 17360]]
populations of mountain whitefish occur in closed drainage basins
within the range of the species and other populations of mountain
whitefish occur in settings that are physically or geographically
isolated (and therefore reproductively isolated) from the remainder of
the taxon. Although mountain whitefish may have lived in the Big Lost
River since the estimated time of their physical isolation some 10,000
years ago in the absence of trout and other large fish, we have no
evidence that this past ecological condition is of any biological or
ecological significance. There is no evidence that the introduction of
multiple species of trout to the Big Lost River over 100 years ago had
any effect on the mountain whitefish population, suggesting that their
previous absence had not altered the mountain whitefish's behavior or
ecology in any biologically significant ways, or resulted in any
locally adapted traits. None of the information available to us
indicates that the setting of the Big Lost River is unique or unusual
in any other aspect of its ecology; we have no information suggesting
the Big Lost River is unusual or unique in any of its ecological
characteristics such as water chemistry, temperature, substrate,
pathogens, or prey species utilized. We conclude that mountain
whitefish occurring in the Big Lost River do not occupy an unusual or
unique ecological setting such as to be biologically or ecologically
significant to the remainder of the taxon to which they belong. We
therefore conclude that mountain whitefish in the Big Lost River do not
meet the significance criterion of the DPS policy based on this factor.
(2) Evidence That Loss of the Discrete Population Segment Would Result
in a Significant Gap in the Range of a Taxon
Mountain whitefish are found throughout mountainous areas of
western North America in the United States and Canada. They are
considered common and widely distributed throughout the upper Snake and
Missouri rivers to the east and northeast, the lower Snake and Columbia
rivers to the west and northwest, and the Bonneville and Lahontan
basins to the south and southwest. In southern Idaho alone, the
population of mountain whitefish is estimated to be 4.7
1.8 million, based on a study of 119,453 km (74,225 mi) of stream
surveys (Meyer et al. 2009, p. 760). The population of mountain
whitefish in the Big Lost River is estimated to be 12,639 adults,
occupying 135 km (83 mi) of stream (Garren et al. 2009, p. 6). The
fraction of the population and its range represented by the mountain
whitefish in the Big Lost River is very small when considered relative
to the remainder of the species' range in southern Idaho. When compared
to the range of mountain whitefish throughout western North America, we
find that the gap in the range that would result from the loss of the
single population of mountain whitefish in the Big Lost River of Idaho
would not be significant, because it is so very small. We therefore
conclude that mountain whitefish in the Big Lost River do not meet the
significance criterion of the DPS policy based on this factor.
(3) Evidence That the Discrete Population Segment Represents the Only
Surviving Natural Occurrence of a Taxon That May Be More Abundant
Elsewhere as an Introduced Population Outside Its Historical Range
This criterion does not apply to mountain whitefish in the Big Lost
River because it is not a population segment representing the only
surviving natural occurrence of the taxon that may be more abundant
elsewhere as an introduced population outside its historical range. We
therefore conclude that mountain whitefish in the Big Lost River do not
meet the significance criterion of the DPS policy based on this factor.
(4) Evidence That the Discrete Population Segment Differs Markedly from
Other Populations of the Species in Its Genetic Characteristics
We evaluated information available to us regarding the genetic
characteristics of mountain whitefish in the Big Lost River in our
evaluation of this population as a potentially separate species or
subspecies (see ``Evaluation of Mountain Whitefish in the Big Lost
River as a Species or Subspecies'' above). Our conclusions from this
evaluation apply here as well, and we include the above discussion
under this factor by reference, although under the DPS policy we
measure the evidence against a slightly different standard (potential
biological and ecological significance to the species as a whole, as
reflected by marked differences in its genetic characteristics). Our
evaluation of the best available scientific information, as detailed
above, does not support the contention that the genetic characteristics
of mountain whitefish in the Big Lost River differ markedly from those
of other populations relative to levels of divergence among other
populations of mountain whitefish. On the contrary, the information
indicates that the genetic distance observed between mountain whitefish
in the Big Lost River and surrounding populations is less than that
observed between other species or subspecies of salmonids to which it
has been compared (Campbell and Kozfkay 2006, p. 7), and is also less
than that observed between individual fish within some populations of
mountain whitefish in other areas (Miller 2006, Figs. 15 and 16). As
detailed above, the evidence indicates the degree of genetic
differentiation between mountain whitefish in the Big Lost River and
surrounding populations is no greater than that observed between many
other populations of mountain whitefish throughout the range of the
species (Campbell and Kofzkay 2006, Figure 3, p. 8; Miller 2006, pp.
27-35; Whiteley et al. 2006, p. 2781). When measuring this evidence
against the DPS standard, we looked for evidence of marked
differentiation of mountain whitefish in the Big Lost River when
compared to other populations of mountain whitefish throughout the
range of the species. We conclude the degree of genetic divergence
observed in this population does not rise to the level of significance
to the taxon as a whole.
As noted above, the most recent genetic work (Miller 2006, pp. 27-
35; Whiteley et al. 2006, pp. 2780-2781) indicates there are several
physically isolated populations of mountain whitefish that, as expected
under a scenario of reduced gene flow, show some divergence from their
presumed common populations of origin. Furthermore, the research
demonstrates that most populations of mountain whitefish sampled have
diverged to the point of possessing unique haplotypes, and other
populations of mountain whitefish exhibit a greater degree of genetic
divergence than observed in mountain whitefish from the Big Lost River
(Campbell and Kozfkay 2006, p. 7). Mountain whitefish, in general,
appear to exhibit a high degree of genetic structure between
populations, as observed in many species of freshwater fishes
(Gyllensten 1985, p. 691; Allendorf and Waples 1996, p. 257; Whiteley
et al. 2006, p. 2783). More importantly, however, scientific
information to indicate that the genetic divergence observed in these
populations confers any fitness advantage or otherwise contributes to
the biological or ecological importance of this population, in relation
to the taxon as a whole, is lacking. Particularly when a population has
gone through a presumed bottleneck, as evidenced by the lack of
microsatellite DNA variation observed in mountain whitefish in the Big
Lost River, the amount of genetic
[[Page 17361]]
distance is expected to increase very quickly (Hedrick 1999, p. 315).
Such increased distance does not, however, automatically confer
biological significance in the absence of any indication of local
adaptive differences.
The Service fully supports conserving the mountain whitefish as a
component of the native biodiversity of the Big Lost River. However,
whether mountain whitefish in the Big Lost River are deserving of
conservation in the name of preserving native biodiversity is not the
same question as whether the mountain whitefish found in the Big Lost
River may qualify as a listable entity under the Act. Additionally,
under the ``significance'' prong of the DPS policy, we are required to
apply a different and specific set of criteria. We find that, based on
the genetic information available and as detailed in our analysis in
the section ``Evaluation of Mountain Whitefish in the Big Lost River as
a Species or Subspecies'' above, mountain whitefish in the Big Lost
River do not differ markedly from other populations of the species in
their genetic characteristics such that they are biologically or
ecologically significant to the species as a whole. Rather, all
available information indicates the level of genetic differentiation is
not unusual for mountain whitefish, when considered in the context of
the species across its range. We acknowledge that mountain whitefish in
the Big Lost River may be genetically distinguished from other nearby
populations, but we do not consider this degree of divergence to be a
marked level of differentiation, particularly in light of the fact that
other populations of mountain whitefish, such as those in the Boise
River (Campbell and Kofzkay 2006, Figure 3. p. 8) and Skokomish River
(Miller 2006, Figure 15c, p. 118), show greater degrees of difference.
We conclude mountain whitefish, in general, exhibit a high degree
of genetic structure, and the mountain whitefish in the Big Lost River
are not any more different or significant to the taxon as a whole than
any of several other populations of mountain whitefish throughout the
species' range. The current genetic characteristics likely reflect a
historical population bottleneck and the overall isolation of the
population, and we have no supportable evidence of any corresponding
phenotypic divergence that may be biologically meaningful or indicative
of local adaptation, such that it should be considered biologically or
ecologically significant to the taxon as a whole. With the additional
consideration that the authority to list DPSes be used ``sparingly,''
we conclude that mountain whitefish occurring in the Big Lost River do
not meet the significance criterion of the DPS policy based on this
factor, due to the number of populations rangewide that exhibit similar
characteristics.
DPS Conclusion
Our DPS policy directs us to evaluate the significance of a
discrete population in the context of its biological and ecological
significance to the remainder of the species to which it belongs. Based
on an analysis of the best available scientific and commercial data, we
conclude that mountain whitefish in the Big Lost River are discrete due
to their physical separation from the remainder of the taxon. Mountain
whitefish in the Big Lost River do not, however, meet any of the four
identified elements in the DPS policy for determining significance, and
we have no information suggesting the population could otherwise be
reasonably justified as being significant. Because the mountain
whitefish occupying the Big Lost River fail to meet our significance
criterion for a DPS under our policy, we conclude this discrete
population is not significant to the taxon to which it belongs, and
therefore does not qualify as a DPS under the Act.
Listable Entity Determination
We have determined that mountain whitefish occurring in the Big
Lost River do not constitute a species or subspecies separate from the
more widespread Prosopium williamsoni. Although the population is
considered discrete, the available scientific evidence indicates this
population is not biologically or ecologically significant to the
species as a whole according to the criteria outlined in our 1996 DPS
policy; consequently this population cannot be considered a DPS. We
therefore find the mountain whitefish in the Big Lost River do not
qualify as a listable entity (species, subspecies, or DPS) under
section 3(16) of the Act. Because we found that the population segment
does not meet the significance element and therefore does not qualify
as a DPS under the Service's DPS policy, we will not proceed with an
evaluation of the status of the population segment under the Act.
Significant Portion of the Range Analysis
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' Having determined that the mountain whitefish in the
Big Lost River is not a listable entity (species, subspecies or DPS)
under the Act, we next consider whether the mountain whitefish in the
Big Lost River constitutes a significant portion of the species' range
and, if so, whether it is in danger of extinction or is likely to
become endangered in the foreseeable future. We consider a portion of a
species' range to be significant if it is part of the current range of
the species and is important to the conservation of the species because
it contributes meaningfully to the representation, resiliency, or
redundancy of the species. The contribution must be at a level such
that its loss would result in a decrease in the ability of the species
to persist.
The first step in determining whether a species is endangered or
threatened in a significant portion of its range is to identify any
portions of the range of the species that warrant further
consideration. 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 are not reasonably likely to be
significant and endangered or threatened. To identify 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. In practice, a
key part of this analysis 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 threats applies only
to portions of the species' range that are not significant, such
portions will not warrant further consideration.
If we identify any portions of a species' range that warrant
further consideration, we then determine whether the species is
endangered or threatened in these portions of its range. Depending on
the biology of the species, its range, and the threats it faces, it may
be more efficient in some cases for the Service to address the
significance question first, and in others the status question first.
Thus, if the Service determines that a portion of the range is not
significant, the Service need not determine whether the species is
endangered or threatened there; conversely, if the Service determines
that the species is not endangered or threatened in a portion of its
range, the Service need not determine if that portion is significant.
However, if the
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Service determines that both a portion of the range of a species is
significant and the species is endangered or threatened there, the
Service will specify that portion of the range as endangered or
threatened under section 4(c)(1) of the Act.
The terms ``resiliency,'' ``redundancy,'' and ``representation''
are intended to be indicators of the conservation value of portions of
the species' range. Resiliency of a species allows the species to
recover from periodic disturbance. A species will likely be more
resilient if large populations exist in high-quality habitat that is
distributed throughout the range of the species in such a way as to
capture the environmental variability within the range of the species.
It is likely that the larger size of a population will help contribute
to the viability of the species. Thus, a portion of the range of a
species may make a meaningful contribution to the resiliency of the
species if the area is relatively large and contains particularly high-
quality habitat or if its location or characteristics make it less
susceptible to certain threats than other portions of the range. When
evaluating whether or how a portion of the range contributes to
resiliency of the species, it may help to evaluate the historical value
of the portion and how frequently the portion is used by the species.
In addition, the portion may contribute to resiliency for other
reasons--for instance, it may contain an important concentration of
certain types of habitat that are necessary for the species to carry
out its life-history functions, such as breeding, feeding, migration,
dispersal, or wintering.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This does not
mean that any portion that provides redundancy is a significant portion
of the range of a species. The idea is to conserve enough areas of the
range such that random perturbations in the system act on only a few
populations. Therefore, each area must be examined based on whether
that area provides an increment of redundancy that is important to the
conservation of the species.
Adequate representation insures that the species' adaptive
capabilities are conserved. Specifically, the portion should be
evaluated to see how it contributes to the genetic diversity of the
species. The loss of genetically based diversity may substantially
reduce the ability of the species to respond and adapt to future
environmental changes. A peripheral population may contribute
meaningfully to representation if there is evidence that it provides
genetic diversity due to its location on the margin of the species'
habitat requirements.
Applying the process described above, we first evaluated whether
the population of mountain whitefish occurring in the Big Lost River
constitutes a significant portion of the range of the species. As noted
earlier, mountain whitefish are found throughout mountainous areas of
western North America in Canada and the United States. In the United
States, they are known to occur in the States of Washington, Oregon,
Idaho, Wyoming, Montana, Colorado, Utah, Nevada, and California
(NatureServe 2009). Mountain whitefish are relatively common and
widespread in most river basins in Idaho (AFS 2007, p. 29), with stream
size documented to be an important factor influencing both the
distribution and abundance of mountain whitefish in the upper Snake
River basin (Meyer et al. 2009, p. 762; Maret et al. 1997, p. 213).
Within the State of Idaho, mountain whitefish are abundant where they
occur. For example, during a recent survey of 2,043 study sites in
Idaho across 119,453 km (74,225 mi) of stream in 21 major river
drainages in the upper Snake River basin (excluding the Big Lost
River), 767 sites in 11 of the 21 river drainages were documented to
support mountain whitefish (Meyer et al. 2009, p. 760). From this
survey the authors also estimated the abundance of mountain whitefish
to be 4.7 1.8 million in southern Idaho, occurring mostly
in streams wider than 15 m (49 ft) (Meyer et al. 2009, p. 764). The
current population of mountain whitefish in the Big Lost River is
estimated to be 12,639 adults (Garren et al. 2009, p. 6) occurring in
approximately 135 km (83 mi) of stream. The mountain whitefish
population occurring in the Big Lost River thus represents less than
0.5 percent of the total estimated numbers of mountain whitefish in
southern Idaho, and occupies approximately 0.1 percent of the stream
miles of the survey. Extending this comparison to consider mountain
whitefish in the Big Lost River relative to the taxon throughout its
range in western North America, the fraction of the species' total
population represented by mountain whitefish in the Big Lost River
would be extremely small.
Although the majority of mountain whitefish occur in riverine
environments, some populations are restricted to lakes or isolated sink
basins. The fact that mountain whitefish in the Big Lost River are
found in a geographically isolated drainage is not significant to the
species as a whole, as other populations of mountain whitefish also
occur in physically isolated settings throughout the range of the
species, such as the Lahontan Basin in California and Nevada, and the
Bonneville Basin in Utah. As described earlier in our DPS analysis, we
could not find any information that the Big Lost river drainage is
ecologically unusual, unique, or otherwise significant to the species
as a whole in any way (for example, in terms of atypical prey species,
water chemistry, or substrate). Based on the best available information
we have on mountain whitefish, the population that occurs in the Big
Lost River does not appear to exist in an unusual or unique ecological
setting, or contain a large portion of the habitat or individuals
relative to the taxon as a whole. Rather, the Big Lost River appears to
constitute an extremely small portion of the species' overall habitat
and number of individuals when compared to the Upper Snake River basin
population of mountain whitefish, and even more so when compared to
mountain whitefish rangewide throughout western North America. We thus
do not consider mountain whitefish in the Big Lost River to provide an
important component of resiliency to the species as a whole.
In terms of representation, mountain whitefish occurring in the Big
Lost River are not recognized as a species or subspecies by the
relevant taxonomic authorities, State of Idaho, and others (Nelson et
al. 2004, p. 86; IDFG 2009; ITIS 2009; NatureServe 2009), and the best
available information indicates that the genetic distance observed
between mountain whitefish in the Big Lost River and surrounding
populations is substantially less than that observed between other
species or subspecies of salmonids (Campbell and Kozfkay 2006, p. 7).
Likewise, as discussed above, information from the most current genetic
assessments of mountain whitefish does not indicate this population is
markedly different or unique in terms of its genetic characteristics,
any more so than many other populations of mountain whitefish
throughout the range of the species. The available evidence indicates
that there is a high degree of genetic structuring between populations
of mountain whitefish, as is frequently observed in populations of
freshwater salmonids (Allendorf and Waples 1996, p. 257; Miller 2006,
p. 25; Whiteley et al. 2006, p. 2783). The degree of genetic
differentiation between mountain whitefish in the Big Lost River and
surrounding populations is no greater than that observed between other
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populations of mountain whitefish (Campbell and Kozfkay 2006, Figure 3,
p. 8; Miller 2006, pp. 22, 29-30; Whiteley et al. 2006, p. 2781). We
thus do not consider mountain whitefish in the Big Lost River to make a
significant contribution to the representation of the species as a
whole.
Finally, mountain whitefish in the Big Lost River group with the
major genetic assemblage of the Upper Snake River and are most
genetically similar to that group. We find it unlikely, however, that
mountain whitefish in the Big Lost River would provide any meaningful
redundancy to the species if other populations of mountain whitefish in
the Upper Snake River basin were to be extirpated by a catastrophic
event. The Big Lost River is geographically separated from the Snake
River and other streams. It is therefore unlikely that fish in the Big
Lost River would be a significant source of mountain whitefish to
recolonize streams within the Upper Snake River.
We have determined the mountain whitefish in the Big Lost River do
not provide a meaningful contribution to the species as a whole with
regard to redundancy, resiliency, and representation of mountain
whitefish throughout their range in western North America. Based upon
this determination, we find the mountain whitefish in the Big Lost
River do not represent a significant portion of the species' range.
Having reached this conclusion, we will not further evaluate the status
of mountain whitefish in the Big Lost River as a significant portion of
the range of the species.
Finding
After a thorough review of the best scientific and commercial
information available, we find that listing the mountain whitefish in
the Big Lost River of Idaho is not warranted. We have determined the
mountain whitefish in the Big Lost River are not a species, subspecies,
or DPS as defined by section 3(16) of the Act, and therefore are not
eligible for listing. In addition, we have further determined the
mountain whitefish in the Big Lost River do not represent a significant
portion of the range of the species Prosopium williamsoni. We therefore
find the mountain whitefish in the Big Lost River are not eligible for
the protections of the Act. Consequently, we are not proceeding with an
evaluation of the conservation status of mountain whitefish in the Big
Lost River relative to the Act's standards for listing as endangered or
threatened. This finding concludes our status review and constitutes
our final response to the petition.
We strongly support ongoing conservation efforts to restore habitat
for the mountain whitefish and other native species residing in the Big
Lost River, and to monitor the status, trends, and threats to this
native population of fish. We emphasize that our determination that
mountain whitefish in the Big Lost River do not constitute a listable
entity under the Act should in no way diminish the value of conserving
this population as an important component of the natural community. We
encourage all interested parties to assist with the management and
conservation of mountain whitefish in the Big Lost River basin and to
preserve all elements of native biodiversity in this ecosystem.
We request that you submit any new information concerning the
status of, or threats to, the mountain whitefish in the Big Lost River
basin to our Idaho Fish and Wildlife Office (see ADDRESSES section)
whenever it becomes available. New information will help us monitor the
mountain whitefish in the Big Lost River basin and encourage their
conservation.
References Cited
A complete list of all references cited in this document is
available on the Internet at http://www.regulations.gov and upon
request from the Idaho Fish and Wildlife Office (see ADDRESSES
section).
Authors
The primary authors of this document are staff members of the Idaho
Fish and Wildlife Office of the U.S. Fish and Wildlife Service (see
ADDRESSES section).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended
(16 U.S.C. 1531 et seq.).
Dated: March 9, 2010.
Daniel M. Ashe,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2010-7674 Filed 4-5-10; 8:45 am]
BILLING CODE 4310-55-S