[Federal Register Volume 79, Number 161 (Wednesday, August 20, 2014)]
[Proposed Rules]
[Pages 49383-49422]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-19353]
[[Page 49383]]
Vol. 79
Wednesday,
No. 161
August 20, 2014
Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Revised 12-Month Finding
on a Petition To List the Upper Missouri River Distinct Population
Segment of Arctic Grayling as an Endangered or Threatened Species;
Proposed Rule
Federal Register / Vol. 79 , No. 161 / Wednesday, August 20, 2014 /
Proposed Rules
[[Page 49384]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2013-0120; 4500030113]
Endangered and Threatened Wildlife and Plants; Revised 12-Month
Finding on a Petition To List the Upper Missouri River Distinct
Population Segment of Arctic Grayling as an Endangered or Threatened
Species
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
revised 12-month finding on a petition to list the Upper Missouri River
distinct population segment (Upper Missouri River DPS) of Arctic
grayling (Thymallus arcticus) as an endangered or threatened species
under the Endangered Species Act of 1973, as amended (Act). After
review of the best available scientific and commercial information, we
find that listing the Upper Missouri River DPS of Arctic grayling is
not warranted at this time. The best available scientific and
commercial information indicates that habitat-related threats
previously identified, including habitat fragmentation, dewatering,
thermal stress, entrainment, riparian habitat loss, and effects from
climate change, for the Upper Missouri River DPS of Arctic grayling
have been sufficiently ameliorated and that 19 of 20 populations of
Arctic grayling are either stable or increasing. This action removes
the Upper Missouri River DPS of the Arctic grayling from our candidate
list. Although listing 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 Upper Missouri River DPS of Arctic grayling or its
habitat at any time.
DATES: The finding announced in this document was made on August 20,
2014.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R6-ES-2013-0120. 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, Montana Ecological Services Office, 585
Shepard Way, Suite 1, Helena, MT 59601. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Jodi Bush, Field Supervisor, Montana
Ecological Services Office (see ADDRESSES); telephone 406-449-5225. 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. We must publish these 12-month findings
in the Federal Register.
Previous Federal Actions
We have published a number of documents on Arctic grayling since
1982, and have been involved in litigation over previous findings. We
describe previous federal actions that are relevant to this document
below.
We published our first status review for the Montana Arctic
grayling (Thymallus arcticus montanus), then thought to be a subspecies
of Arctic grayling, in a Federal Register document on December 30, 1982
(47 FR 58454). In that document, we designated the purported
subspecies, Montana Arctic grayling, as a Category 2 species. At that
time, we designated a species as Category 2 if a listing as endangered
or threatened was possibly appropriate, but we did not have sufficient
data to support a proposed rule to list the species.
On October 9, 1991, the Biodiversity Legal Foundation and George
Wuerthner petitioned us to list the fluvial (riverine) populations of
Arctic grayling in the Upper Missouri River basin as an endangered
species throughout its historical range in the coterminous United
States. We published a notice of a 90-day finding in the January 19,
1993, Federal Register (58 FR 4975), concluding the petitioners
presented substantial information indicating that listing the fluvial
Arctic grayling of the Upper Missouri River in Montana and northwestern
Wyoming may be warranted. This finding also noted that taxonomic
recognition of the Montana Arctic grayling (Thymallus arcticus
montanus) as a subspecies (previously designated as a category 2
species) was not widely accepted, and that the scientific community
generally considered this population a geographically isolated member
of the wider species (T. arcticus).
On July 25, 1994, we published notification of a 12-month finding
in the Federal Register (59 FR 37738), concluding that listing the DPS
of fluvial Arctic grayling in the Upper Missouri River was warranted
but precluded by other higher priority listing actions. This DPS
determination predated our DPS policy (61 FR 4722, February 7, 1996),
so the entity did not undergo a DPS analysis as described in the
policy. The 1994 finding placed fluvial Arctic grayling of the Upper
Missouri River on the candidate list and assigned it a listing priority
of 9, indicating that the threats were imminent but of moderate to low
magnitude.
On May 31, 2003, the Center for Biological Diversity and Western
Watersheds Project (Plaintiffs) filed a complaint in U.S. District
Court in Washington, DC, challenging our 1994 ``warranted but
precluded'' determination for the DPS of fluvial Arctic grayling in the
Upper Missouri River basin. On May 4, 2004, we elevated the listing
priority number of the fluvial Arctic grayling to 3 (69 FR 24881),
indicating threats that were imminent and of high magnitude. On July
22, 2004, the Plaintiffs amended their complaint to challenge our
failure to emergency list this population. We settled with the
Plaintiffs in August 2005, and we agreed to submit a revised
determination on whether this population warranted listing as
endangered or threatened to the Federal Register on or before April 16,
2007.
On April 24, 2007, we published a revised 12-month finding on the
petition to list the Upper Missouri River DPS of fluvial Arctic
grayling (72 FR 20305) (``2007 finding''). In this finding, we
determined that fluvial Arctic grayling of the upper Missouri River did
not constitute a species, subspecies, or DPS under the Act. Therefore,
we found that the upper Missouri River
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population of fluvial Arctic grayling was not a listable entity under
the Act, and, as a result, listing was not warranted. With that
document, we withdrew the fluvial Arctic grayling from our candidate
list.
On November 15, 2007, the Center for Biological Diversity,
Federation of Fly Fishers, Western Watersheds Project, George
Wuerthner, and Pat Munday filed a complaint (CV-07-152, in the District
Court of Montana) to challenge our 2007 finding. We settled this
litigation on October 5, 2009. In the stipulated settlement, we agreed
to: (a) Publish, on or before December 31, 2009, a document in the
Federal Register soliciting information on the status of the upper
Missouri River Arctic grayling; and (b) submit, on or before August 30,
2010, a new 12-month finding for the upper Missouri River Arctic
grayling to the Federal Register.
On October 28, 2009, we published in the Federal Register a notice
of intent to conduct a status review of Arctic grayling (Thymallus
arcticus) in the upper Missouri River system (74 FR 55524). To ensure
the status review was based on the best available scientific and
commercial data, we requested information on the taxonomy, biology,
ecology, genetics, and population status of the Arctic grayling of the
upper Missouri River system; information relevant to consideration of
the potential DPS status of Arctic grayling of the upper Missouri River
system; threats to the species; and conservation actions being
implemented to reduce those threats in the upper Missouri River system.
That document further specified that the status review might consider
various DPS designations that include different life histories of
Arctic grayling in the upper Missouri River system and different DPS
configurations, including fluvial, adfluvial (lake populations), or all
life histories of Arctic grayling in the upper Missouri River system.
On September 8, 2010, we published a revised 12-month finding on
the petition to list the Upper Missouri River DPS of Arctic grayling
(75 FR 54708) (``2010 finding''). In this finding, we determined that
fluvial and adfluvial Arctic grayling of the upper Missouri River did
constitute a DPS under the Act. Further, we found that a DPS
configuration including both adfluvial and fluvial life histories was
the most appropriate for the long-term conservation of Arctic grayling
because genetic evidence indicated that fluvial and adfluvial life-
history forms did not represent distinct evolutionary lineages. We
concluded by finding that the Upper Missouri River DPS of Arctic
grayling was warranted for listing under the Act, but precluded by
other higher priority listing actions.
On September 9, 2011, we reached an agreement with plaintiffs in
Endangered Species Act Section 4 Deadline Litig., Misc. Action No. 10-
377 (EGS), MDL Docket No. 2165 (D. D.C.) (known as the ``MDL case'') on
a schedule to publish proposed listing rules or not-warranted findings
for the species on our candidate list. This agreement stipulated that
we would submit for publication in the Federal Register either a
proposed listing rule for the Upper Missouri River DPS of Arctic
grayling, or a not-warranted finding, no later than the end of Fiscal
Year 2014.
On November 26, 2013, we published a document in the Federal
Register (78 FR 70525) notifying the public that we were initiating a
status review of the Upper Missouri River DPS of Arctic grayling to
determine whether the entity meets the definition of an endangered or
threatened species under the Act. That document requested general
information (taxonomy, biology, ecology, genetics, and status) on the
Arctic grayling of the upper Missouri River system, as well as
information on the conservation status of, threats to, planned and
ongoing conservation actions for, habitat selection of, habitat
requirements of, and considerations concerning the possible designation
of critical habitat for the Arctic grayling of the upper Missouri River
system.
This document constitutes a revised 12-month finding (``2014
finding'') on whether to list the Upper Missouri River DPS of Arctic
grayling (Thymallus arcticus) as endangered or threatened under the
Act, and fulfills our commitments under the MDL case.
Species Information
Taxonomy and Species Description
The Arctic grayling (Thymallus arcticus) is a fish belonging to the
family Salmonidae (salmon, trout, charr, whitefishes), subfamily
Thymallinae (graylings), and it is represented by a single genus,
Thymallus. Arctic grayling have elongate, laterally compressed, trout-
like bodies with deeply forked tails, and adults typically average 300-
380 millimeters (mm) (12-15 inches (in.)) in length. Coloration can be
striking, and varies from silvery or iridescent blue and lavender, to
dark blue (Behnke 2002, pp. 327-328). A prominent morphological feature
of Arctic grayling is the sail-like dorsal fin, which is large and
vividly colored with rows of orange to bright green spots, and often
has an orange border (Behnke 2002, pp. 327-328).
For more detail on taxonomy and species description, see the 2010
finding (75 FR 54708).
Distribution
Arctic grayling are native to Arctic Ocean drainages of Alaska and
northwestern Canada, as far east as Hudson's Bay, and westward across
northern Eurasia to the Ural Mountains (Scott and Crossman 1998, pp.
301-302; Froufe et al. 2005, pp. 106-107; Weiss et al. 2006, pp. 511-
512). In North America, they are native to northern Pacific Ocean
drainages as far south as the Stikine River in British Columbia (Nelson
and Paetz 1991, pp. 253-256; Behnke 2002, pp. 327-331).
For a full discussion on the global distribution of Arctic
grayling, see the 2010 finding (75 FR 54709-54710). Here, we focus on
the distribution of Arctic grayling within the conterminous United
States.
Distribution in the Conterminous United States
Two disjunct groups of Arctic grayling were native to the
conterminous United States: One in the upper Missouri River basin in
Montana and Wyoming (currently extant only in Montana); and another in
Michigan that was extirpated in the late 1930s (Hubbs and Lagler 1949,
p. 44), and has not been detected since.
During the status review process, the Service received information
indicating that Arctic grayling may have also been native to areas
outside the Upper Missouri River basin in Montana and Wyoming. This
information included multiple historical newspaper clippings and
several reports from early Army expeditions purporting that Arctic
grayling were captured in the Yellowstone River drainage in Montana and
the Snake River drainage in Idaho (Shea 2014, entire). Some of these
reports even included descriptions of captured fish. However, none of
the descriptions mentions the colorful, sail-like dorsal fin of Arctic
grayling, a prominent feature that clearly distinguishes Arctic
grayling from other salmonids. In addition, a similar species
resembling Arctic grayling (i.e., mountain whitefish) is native to both
the Yellowstone River drainage and Snake River drainage. Mountain
whitefish were sometimes referred to as ``grayling'' in some areas of
the West (Ellis 1914, p. 75). Thus, it is likely that early reports of
Arctic grayling occurring outside the upper Missouri River basin were
mountain whitefish misidentified as Arctic grayling. Therefore, without
information to the contrary, we consider Arctic grayling to
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be native only to the upper Missouri River basin in Montana and Wyoming
and to Michigan.
Native Distribution of Arctic Grayling in the Upper Missouri River
Basin
The first Euro-American ``discovery'' of Arctic grayling in North
America is attributed to members of the Lewis and Clark Expedition, who
encountered the species in the Beaverhead River in August 1805 (Nell
and Taylor 1996, p. 133). Vincent (1962, p. 11) and Kaya (1992, pp. 47-
51) synthesized accounts of Arctic grayling occurrence and abundance
from historical surveys and contemporary monitoring to determine the
historical distribution of the species in the upper Missouri River
system (Figure 1). We base our conclusions on the historical
distribution of Arctic grayling in the upper Missouri River basin on
these two reviews. Arctic grayling were widely but irregularly
distributed in the upper Missouri River system above the Great Falls in
Montana and in northwest Wyoming within the present-day location of
Yellowstone National Park (Vincent 1962, p. 11). They were estimated to
inhabit up to 2,000 kilometers (km) (1,250 miles (mi)) of stream
habitat until the early 20th century (Kaya 1992, pp. 47-51). Arctic
grayling were reported in the mainstem Missouri River, as well as in
the Smith, Sun, Jefferson, Madison, Gallatin, Big Hole, Beaverhead, and
Red Rock Rivers (Vincent 1962, p. 11; Kaya 1992, pp. 47-51; USFWS 2007;
72 FR 20307, April 24, 2007). Anecdotal accounts report that the
species may have been present in the Ruby River, at least seasonally
(Magee 2005, pers. comm.), and were observed there as recently as the
early 1970s (Holton, undated).
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[GRAPHIC] [TIFF OMITTED] TP20AU14.000
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Fluvial Arctic grayling were historically widely distributed in the
upper Missouri River basin, but a few adfluvial populations also were
native to the basin. For example, Arctic grayling are native to Red
Rock Lakes, in the Centennial Valley (Vincent 1962, pp. 112-121; Kaya
1992, p. 47). Vincent (1962, p. 120) stated that Red Rock Lakes were
the only natural lakes in the upper Missouri River basin accessible to
colonization by Arctic grayling, and concluded that Arctic grayling
there were the only native adfluvial population in the basin. However,
Arctic grayling were also native to Elk Lake (in the Centennial Valley;
Kaya 1990, p. 44) and a few small lakes in the upper Big Hole River
drainage, based on recent genetic information (Peterson and Ardren
2009, p. 1768).
The distribution of native Arctic grayling in the upper Missouri
River went through a dramatic reduction in the first 50 years of the
20th century, especially in riverine habitats (Vincent 1962, pp. 86-90,
97-122, 127-129; Kaya 1992, pp. 47-53). The native populations that
formerly resided in the
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Smith, Sun, Jefferson, Beaverhead, Gallatin, and mainstem Missouri
Rivers are considered extirpated, and the only remaining native fluvial
population is found in the Big Hole River and some of its tributaries
(Kaya 1992, pp. 51-53). The fluvial form currently occupies less than
10 percent of its historical range in the Missouri River system (Kaya
1992, p. 51). Other native populations in the upper Missouri River
occur in two small, headwater lakes in the upper Big Hole River system
(Miner and Mussigbrod Lakes); the upper Ruby River (recently
reintroduced from Big Hole River stock); the Madison River upstream
from Ennis Reservoir; Elk Lake in the Centennial Valley (recently
reintroduced from Red Rock Lakes stock); and the Red Rock Lakes in the
Centennial Valley (Everett 1986, p. 7; Kaya 1992, p. 53; Peterson and
Ardren 2009, pp. 1762, 1768; see Figure 1).
Introduced Lake-Dwelling Arctic Grayling in the Upper Missouri River
Basin
From 1898 through the 1960s, an estimated 100 million Arctic
grayling were stocked across Montana and other western States. The
sources of these stockings varied through time as different State,
Federal, and private hatchery operations were created, but the ultimate
source for all hatcheries in Montana appears to be stock from two
Montana populations: Centennial Valley and Madison River (Peterson and
Ardren 2009, p. 1767; Leary 2014, unpublished data; MFISH 2014a).
Arctic grayling derived from these two sources were stocked on top of
every known native Arctic grayling population in the upper Missouri
River basin. In addition, Arctic grayling were stocked in multiple high
elevation lakes, some of which likely were historically fishless.
There are 20 known, introduced Arctic grayling populations that
exist in the upper Missouri River basin. These 20 populations, along
with the 6 populations existing in native habitat, comprise the
listable entity (total of 26 populations) of Arctic grayling in the
upper Missouri River basin. However, six of these introduced
populations are considered to have low conservation value because they
occupy unnatural habitat, are not self-sustaining, or are used as
captive brood reserves. These six populations are Axolotl Lake, Green
Hollow Lake, Sunnyslope Canal, Tunnel Lake, South Fork Sun River, and
Elk Lake. The Axolotl and Green Hollow populations are captive brood
reserves maintained in natural lakes for reintroduction purposes.
Sunnyslope Canal is a fluvial population that occurs in unnatural
habitat (irrigation canal). Tunnel Lake is stocked with ``rescued''
fish from Sunnyslope Canal, but lacks a spawning tributary and is
consequently not self-sustaining (SSA 2014). South Fork Sun River is a
small fluvial population that resides in about \1/4\ mile of stream
during the summer and is not considered self-sustaining (SSA 2014). The
Elk Lake population is a genetic replicate of the Centennial Valley
population, but no documented spawning has occurred to date (Jaeger
2014a, pers. comm.); thus this population is not currently considered
self-sustaining. For these reasons, we primarily focus our analysis on
the populations considered to have high conservation value; those
populations that are self-sustaining, in natural habitats, and wild.
The 14 known remaining introduced, lake-dwelling (adfluvial) Arctic
grayling populations within the upper Missouri River basin are likely
the result of historical stocking (Table 1). In our 2010 finding, we
considered and discussed the conservation value of these populations.
Based on the information available at that time, we considered these
introduced populations to not have conservation value for multiple
reasons. Below, we list each of the reasons for this conclusion as
provided in the 2010 finding, and provide an updated assessment and
conclusion about the potential conservation value of these populations,
based on new information obtained since 2010.
Table 1--Geographic Distribution, Genetic Status, and Source of Introduced Adfluvial Arctic Grayling Populations
in the Upper Missouri River Basin
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Genetic
Population Drainage analysis Source \a\ Citation
completed?
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Agnes Lake................... Big Hole....... No............. Madison/ MFISH 2014a.
Centennial.
Odell Lake................... Big Hole....... Yes............ Centennial..... Peterson and Ardren 2009, p.
1766; Leary 2014, unpublished
data.
Bobcat Lake.................. Big Hole....... Yes............ Centennial..... Peterson and Ardren 2009, p.
1766; Leary 2014, unpublished
data.
Schwinegar Lake.............. Big Hole....... No............. Madison/ ..............................
Centennial.\c\.
Pintlar Lake................. Big Hole....... Yes............ Madison/ Leary 2014, unpublished data.
Centennial.
Deer Lake.................... Gallatin....... Yes............ Madison/ Leary 2014, unpublished data.
Centennial.
Emerald Lake................. Gallatin....... Yes............ Madison/ Leary 2014, unpublished data.
Centennial.
Grayling Lake................ Gallatin....... Yes............ Madison/ Leary 2014, unpublished data.
Centennial.
Hyalite Lake................. Gallatin....... Yes............ Madison/ Leary 2014, unpublished data.
Centennial.
Diversion Lake............... Sun............ Yes \b\........ Big Hole....... Horton 2014a, pers. comm.;
Magee 2014, pers. comm.
Gibson Reservoir............. Sun............ Yes \b\........ Big Hole....... Horton 2014a, pers. comm.;
Magee 2014, pers. comm.
Lake Levale.................. Sun............ Yes \b\........ Big Hole....... Horton 2014a, pers. comm.;
Magee 2014, pers. comm.
Park Lake.................... Missouri....... No............. Madison/ ..............................
Centennial.\c\.
Grebe Lake................... Madison........ Yes............ Centennial..... Peterson and Ardren 2009, p.
1766; Varley 1981, p. 11.
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\a\ Origin of source stock was determined by genetic analysis and through analysis of historical stocking
records and scientific literature, in some cases. Where multiple sources are cited, fish from each population
were known to be stocked, although the genetic contribution of each donor population to the current population
structure is unknown.
\b\ These populations are the result of reintroductions using known sources of Montana origin.
\c\ Schwinegar and Park Lakes Arctic grayling populations are likely from Montana-origin sources due to
proximity to other lakes with known Montana origin; however, definitive evidence is lacking.
1. The Service interprets the Act to provide a statutory directive
to conserve species in their native ecosystems (49 FR 33885, August 27,
1984) and to conserve genetic resources and biodiversity over a
representative portion of a taxon's historical occurrence (61 FR 4722,
February 7, 1996). Since most of the introduced populations of Arctic
grayling were of unknown genetic origin and in lakes that were likely
historically fishless,
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these populations were considered in 2010 to be outside the species'
native range, and we concluded that they did not appear to add
conservation value to the DPS.
Since 2010, new genetic information from 7 of the 14 introduced
populations indicates there are moderate to high levels of genetic
diversity within and among these populations, and indicates these
populations were derived from native sources within the upper Missouri
River basin (Leary 2014, unpublished data; Table 1). In addition,
stocking records show common stocking sources for introduced
populations that were genotyped (as described previously) and the two
populations that were not genotyped (the remaining 3 populations were
reintroductions of known Montana origin sources; Table 1). Thus, it
appears that all 14 introduced Arctic grayling populations contain
moderate to high levels of genetic diversity of Arctic grayling in the
upper Missouri River basin that was not captured within the DPS
designation in the 2010 finding.
The Service's current interpretation of the Act is consistent with
that in the 2010 finding; we believe it is important to conserve
species in their native ecosystems and to conserve genetic resources
and biodiversity over a representative portion of a taxon's historical
occurrence. In light of the new genetics information gained since 2010
(Leary 2014, unpublished data), we also believe it is important to
acknowledge the moderate to high levels of genetic diversity within the
introduced populations in the upper Missouri River basin and the
potential adaptive capabilities represented by this diversity. All
Arctic grayling populations (introduced or not) currently within the
upper Missouri River basin are derived from a common ancestor and have
a distinct evolutionary trajectory relative to the historical founding
populations in Canada and Alaska. Thus, Arctic grayling originating
from and currently within the upper Missouri River basin represent the
southernmost assemblage of the species, facing similar selection
pressures and evolving independent of more northern populations.
The introduced Arctic grayling populations in the upper Missouri
River basin occupy, for the most part, high-elevation habitats that are
high-quality because of intact riparian areas and a consistent supply
of cool water. Given the predicted effects of climate change in the
West (see discussion under ``Climate Change'' in Factor A below), these
types of habitats are the same habitats that the Service would explore
for long-term conservation of Arctic grayling, if needed, because they
may serve as thermal refugia as temperatures rise and provide greater
redundancy in case of catastrophic events.
2. In 2010, the Service concluded there did not appear to be any
formally recognized conservation value for the introduced populations
of Arctic grayling in the upper Missouri River basin because they were
not being used in conservation or restoration programs. This conclusion
was based on an interpretation of a National Marine Fisheries Service
final policy on the consideration of hatchery-origin fish in Endangered
Species Act listing determinations for Pacific salmon and steelhead
(anadromous Oncorhynchus spp.) (NMFS 2005, entire).
Until recently, the genetic structure and source of these
introduced populations were unknown. Populations with a high likelihood
of being Montana origin were used for conservation purposes (e.g.,
reintroductions) as a precautionary approach to Arctic grayling
conservation. Now that the amount of genetic diversity within and among
the introduced Arctic grayling populations and their source(s) are
known, it is probable these introduced populations could be used in
future conservation actions as source stock, if needed.
3. In 2010, the Service indicated there were concerns that
introduced, lake-dwelling Arctic grayling populations could pose
genetic risks to the native fluvial population (i.e., Big Hole
Population) as cited in the Montana Fluvial Arctic Grayling Restoration
Plan (``Restoration Plan,'' 1995, p. 15). In the Restoration Plan,
Arctic grayling populations in Agnes, Schwinegar, Odell, Miner and
Mussigbrod lakes were identified as potential threats to the genetic
integrity of the Big Hole River population because of hydrologic
connectivity between these lakes and the Big Hole River and the
potential for genetic mixing.
Recently, genetic analyses have confirmed reproductive isolation
among extant Arctic grayling populations in the upper Missouri River
basin and within the Big Hole River watershed (Peterson and Ardren
2009, p. 1770; Leary 2014, unpublished data). In addition, multiple
historical stockings have occurred in the Big Hole River from other
sources within the upper Missouri River basin. Recent genetic analysis
found no evidence of a significant genetic contribution from historical
stocking on the current genetic structure of Arctic grayling in the Big
Hole River (Peterson and Ardren 2009, p. 1768). Thus, we now conclude
that the concern that lake-dwelling populations within the Big Hole
River watershed could pose genetic risks to the Big Hole River fluvial
population appears unfounded.
4. In 2010, the Service concluded that introduced populations of
Arctic grayling in the upper Missouri River basin had no conservation
value because these populations apparently had been isolated from their
original source stock for decades without any supplementation from the
wild and were established without any formal genetic consideration to
selecting and mating broodstock.
It is now apparent from our review of historical stocking records
that many of these introduced populations received multiple stockings
from the same source or multiple stockings from several different
sources over a wide range of years (MFISH 2014a, unpublished data).
Additionally, most individual stockings involved a large number of eggs
or fry (up to 1 million for some stockings). Cumulatively, this
information suggests several points. First, stockings that used a large
number of eggs or fry necessitate that gametes from multiple brood fish
were used per stocking, given the physical constraints of number of
eggs per unit body size of female Arctic grayling. Second, stockings in
most of the introduced populations occurred over many years (up to 60
years in some cases). This indicates different cohorts of Arctic
grayling had to be used, since the generation time of Arctic grayling
is approximately 3.5 years in the upper Missouri River basin
(references in Dehaan et al. 2014, p. 10). Lastly, the new genetic
analyses from seven of the introduced Arctic grayling populations
indicate moderate to high levels of genetic diversity within the
populations. This result could likely only be obtained from the
founding of these populations using large numbers of brood fish and
gametes over multiple years. Mutation is unlikely to have accounted for
these levels of genetic diversity over a relatively short time period
of isolation (Freeman and Herron 2001, p. 143).
For perspective, Montana Fish, Wildlife, and Parks has developed
guidelines for the establishment and maintenance of Arctic grayling
broodstock. To adequately capture most of the genetic variation in a
source population, the crossing of a minimum of 25 male and 25 female
Arctic grayling is currently recommended (Leary 1991, p. 2151). It is
likely that the historical stockings used to found the introduced
Arctic grayling populations in the upper Missouri River basin equaled
or exceeded this through stocking large
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numbers of eggs or fry over multiple years.
5. In 2010, the Service concluded that the source populations used
to found the introduced Arctic grayling populations in the upper
Missouri River drainage were not well documented (Peterson and Ardren
2009, p. 1767), so we could not be certain of whether these Arctic
grayling were of local origin.
Since 2010, new genetic information (Leary 2014, unpublished data)
and review of historical stocking records (MFISH 2014a, unpublished
data) indicate the founding populations used for stocking are local and
believed representative of the Upper Missouri River DPS of Arctic
grayling, and contain moderate to high levels of genetic diversity.
6. In 2010, the Service concluded the primary intent of culturing
and introducing Arctic grayling populations within the upper Missouri
River basin was to provide recreational fishing opportunities in high
mountain lakes, and that, therefore, these introduced populations had
no conservation value.
Since 2010, review of the historical literature indicates adfluvial
Arctic grayling populations were presumably stocked both for
recreational fishing and conservation purposes (Brown 1943, pp. 26-27;
Nelson 1954, p. 341; Vincent 1962, p. 151). Following the drought in
the 1930s, conservation stockings of Arctic grayling were advocated
because most rivers and streams were dewatered, prompting fish managers
to introduce Arctic grayling into habitats with a more consistent
supply of cool water (e.g., high-elevation mountain lakes; Brown 1943,
pp. 26-27; Nelson 1954, p. 341; Vincent 1962, p. 151).
In conclusion, introduced populations of Arctic grayling
established within the upper Missouri River basin, whether they were
originally established for recreational fishing or conservation
purposes, captured moderate to high levels of genetic diversity of
upper Missouri River basin Arctic grayling. The potential adaptive
capabilities represented by this genetic diversity have conservation
value, particularly in a changing climate. These populations reside in
high-quality habitat, the same habitat the Service would look to for
long-term conservation, if needed. Thus, the introduced populations of
Arctic grayling within the upper Missouri River basin have conservation
value, and, therefore, we include them in our analysis of a potential
DPS of Arctic grayling.
Origins, Biogeography, and Genetics of Arctic Grayling in North America
North American Arctic grayling are most likely descended from
Eurasian Thymallus that crossed the Bering land bridge during or before
the Pleistocene glacial period (Stamford and Taylor 2004, pp. 1533,
1546). There were multiple opportunities for freshwater faunal exchange
between North America and Asia during the Pleistocene, but genetic
divergence between North American and Eurasian Arctic grayling suggests
that the species could have colonized North America as early as the
mid-late Pliocene (more than 3 million years ago) (Stamford and Taylor
2004, p. 1546). Genetic studies of Arctic grayling using mitochondrial
DNA (mtDNA, maternally inherited DNA located in cellular organelles
called mitochondria) and microsatellite DNA (repeating sequences of
nuclear DNA) have shown that North American Arctic grayling consist of
at least three major lineages that originated in distinct Pleistocene
glacial refugia (Stamford and Taylor 2004, p. 1533). These three groups
include a South Beringia lineage found in western Alaska to northern
British Columbia, Canada; a North Beringia lineage found on the North
Slope of Alaska, the lower Mackenzie River, and to eastern
Saskatchewan; and a Nahanni lineage found in the lower Liard River and
the upper Mackenzie River drainage in northeastern British Columbia and
southeastern Yukon (Stamford and Taylor 2004, pp. 1533, 1540). Arctic
grayling from the upper Missouri River basin were tentatively placed in
the North Beringia lineage because a small sample (three individuals)
of Montana Arctic grayling shared a mtDNA haplotype (form of the mtDNA)
with populations in Saskatchewan and the lower Peace River, British
Columbia (Stamford and Taylor 2004, p. 1538).
The existing mtDNA data suggest that Missouri River Arctic grayling
share a common ancestry with the North Beringia lineage, but other
genetic markers (e.g., allozymes, microsatellites) and biogeographic
history indicate that Missouri River Arctic grayling have been
physically and reproductively isolated from northern populations for
millennia. Pre-glacial colonization of the Missouri River basin by
Arctic grayling was possible because the river flowed to the north and
drained into the Arctic-Hudson Bay prior to the last glacial cycle
(Cross et al. 1986, pp. 374-375; Pielou 1991, pp. 194-195). Low mtDNA
diversity observed in a small number of Montana Arctic grayling samples
and a shared ancestry with Arctic grayling from the North Beringia
lineage suggest a more recent, post-glacial colonization of the upper
Missouri River basin. In contrast, microsatellite DNA show substantial
divergence between Montana and Saskatchewan (i.e., same putative mtDNA
lineage) (Peterson and Ardren 2009, entire). Differences in the
frequency and size distribution of microsatellite alleles between
Montana populations and two Saskatchewan populations indicate that
Montana Arctic grayling have been isolated long enough for mutations
(i.e., evolution) to be responsible for the observed genetic
differences.
Additional comparison of 21 Arctic grayling populations from
Alaska, Canada, and the Missouri River basin using 9 of the same
microsatellite loci as Peterson and Ardren (2009, entire) further
supports the distinction of Missouri River Arctic grayling relative to
populations elsewhere in North America (USFWS, unpublished data).
Analyses of these data using two different methods clearly separates
sample fish from 21 populations into two clusters: One cluster
representing populations from the upper Missouri River basin, and
another cluster representing populations from Canada and Alaska (USFWS,
unpublished data). These new data, although not yet peer reviewed,
support the interpretation that the previous analyses of Stamford and
Taylor (2004, entire) underestimated the distinctiveness of Missouri
River Arctic grayling relative to other sample populations, likely
because of the combined effect of small sample sizes and the lack of
variation observed in the Missouri River for the markers used in that
study (Stamford and Taylor 2004, pp. 1537-1538). Thus, these recent
microsatellite DNA data suggest that Arctic grayling may have colonized
the Missouri River before the onset of Wisconsin glaciation (more than
80,000 years ago).
Genetic relationships among native and introduced populations of
Arctic grayling in Montana have recently been investigated (Peterson
and Ardren 2009, entire). Introduced, lake-dwelling populations of
Arctic grayling trace some of their original ancestry to the Centennial
Valley (Peterson and Ardren 2009, p. 1767), and stocking of hatchery
Arctic grayling did not have a large effect on the genetic composition
of the extant native populations (Peterson and Ardren 2009, p. 1768).
Differences between native populations of the two Arctic grayling
ecotypes (adfluvial, fluvial) are not as large as differences resulting
from geography (i.e., drainage of origin). For example, native
adfluvial Arctic grayling populations from
[[Page 49391]]
different lakes are genetically different (Peterson and Ardren 2009, p.
1766).
Habitat
Arctic grayling generally require clear, cold water, and are
characterized as belonging to a ``coldwater'' group of salmonids, which
also includes bull trout (Salvelinus confluentus) and Arctic char
(Salvelinus alpinus) (Selong et al. 2001, p. 1032). Arctic grayling
optimal thermal habitat is between 7 to 17 [deg]C (45 to 63 [deg]F),
but becomes unsuitable above 20 [deg]C (68 [deg]F) (Hubert et al. 1985,
p. 24). Arctic grayling fry may be more tolerant of high water
temperature than adults (LaPerriere and Carlson 1973, p. 30; Feldmeth
and Eriksen 1978, p. 2041).
Having a broad, nearly circumpolar distribution, Arctic grayling
occupy a variety of habitats including small streams, large rivers,
lakes, and even bogs (Northcote 1995, pp. 152-153; Scott and Crossman
1998, p. 303). They may even enter brackish water (less than or equal
to 4 parts per thousand salt content) when migrating between adjacent
river systems (West et al. 1992, pp. 713-714). Native populations are
found at elevations ranging from near sea level, such as in Bristol
Bay, Alaska, to high-elevation montane valleys (more than 1,830 meters
(m) or 6,000 feet (ft)), such as the Big Hole River and Centennial
Valley in southwestern Montana. Despite this broad distribution, Arctic
grayling have specific habitat requirements that can constrain their
local distributions, especially water temperature and channel gradient.
At the local scale, Arctic grayling prefer cold water and are often
associated with spring-fed habitats in regions with warmer climates
(Vincent 1962, p. 33). Arctic grayling are generally not found in
swift, high-gradient streams, and Vincent (1962, pp. 36-37, 41-43)
characterized typical Arctic grayling habitat in Montana (and Michigan)
as low-to-moderate gradient (less than 4 percent) streams and rivers
with low-to-moderate water velocities (less than 2 feet/sec (60
centimeters/sec)). Juvenile and adult Arctic grayling in streams and
rivers spend much of their time in pool habitat (Kaya 1990 and
references therein, p. 20; Lamothe and Magee 2003, pp. 13-14).
Breeding
Arctic grayling typically spawn in the spring or early summer,
depending on latitude and elevation (Northcote 1995, p. 149). In
Montana, Arctic grayling generally spawn from late April to mid-May by
depositing adhesive eggs over gravel substrate without excavating a
nest (Kaya 1990, p. 13; Northcote 1995, p. 151). In general, the
reproductive ecology of Arctic grayling differs from other salmonid
species (trout and salmon) in that Arctic grayling eggs tend to be
comparatively small; thus, they have higher relative fecundity (females
have more eggs per unit body size). Males establish and defend spawning
territories rather than defending access to females (Northcote 1995,
pp. 146, 150-151). The time required for development of eggs from
embryo until they emerge from stream gravel and become swim-up fry
depends on water temperature (Northcote 1995, p. 151). In the upper
Missouri River basin, development from embryo to fry averages about 3
weeks (Kaya 1990, pp. 16-17). Small, weakly swimming fry (typically 1-
1.5 centimeters (cm) (0.4-0.6 in.) at emergence) prefer low-velocity
stream habitats (Armstrong 1986, p. 6; Kaya 1990, pp. 23-24; Northcote
1995, p. 151).
Arctic grayling of all ages feed primarily on aquatic and
terrestrial invertebrates captured on or near the water surface, but
also will feed opportunistically on fish and fish eggs (Northcote 1995,
pp. 153-154; Behnke 2002, p. 328). Feeding locations for individual
fish are typically established and maintained through size-mediated
dominance hierarchies where larger individuals defend favorable feeding
positions (Hughes 1992, p. 1996).
General Life History Diversity
Migratory behavior is a common life-history trait in salmonid
fishes such as Arctic grayling (Armstrong 1986, pp. 7-8; Northcote
1995, pp. 156-158; 1997, pp. 1029, 1031-1032, 1034). In general,
migratory behavior in Arctic grayling and other salmonids results in
cyclic patterns of movement between refuge, rearing-feeding, and
spawning habitats (Northcote 1997, p. 1029).
Arctic grayling may move to refuge habitat as part of a regular
seasonal migration (e.g., in winter), or in response to episodic
environmental stressors (e.g., high summer water temperatures). In
Alaska, Arctic grayling in rivers typically migrate downstream in the
fall, moving into larger streams or mainstem rivers that do not
completely freeze (Armstrong 1986, p. 7). In Arctic rivers, fish often
seek overwintering habitat influenced by groundwater (Armstrong 1986,
p. 7). In some drainages, individual fish may migrate considerable
distances (greater than 150 km or 90 mi) to overwintering habitats
(Armstrong 1986, p. 7). In the Big Hole River, Montana, similar
downstream and long-distance movement to overwintering habitat has been
observed in Arctic grayling (Shepard and Oswald 1989, pp. 18-21, 27).
In addition, Arctic grayling in the Big Hole River may move downstream
in proximity to colder tributary streams in summer when thermal
conditions in the mainstem river become stressful (Lamothe and Magee
2003, p. 17).
In spring, mature Arctic grayling leave overwintering areas and
migrate to suitable spawning sites. In river systems, this typically
involves an upstream migration to tributary streams or shallow riffles
within the mainstem (Armstrong 1986, p. 8; Shepard and Oswald 1989; p.
18). Arctic grayling in lakes typically migrate to either the inlet or
outlet to spawn (Armstrong 1986, p. 8; Kaya 1989, p. 474; Northcote
1995 p. 148). In some situations, Arctic grayling exhibit natal homing,
whereby individuals spawn in or near the location where they were born
(Northcote 1995 pp. 157-160; Boltz and Kaeding 2002, p. 22); however,
it is unclear what factors may be influencing the extent of this
phenomenon.
Fry from river populations typically seek feeding and rearing
habitats in the vicinity of where they were spawned (Armstrong 1986,
pp. 6-7; Kaya and Jeanes 1995, p. 455; Northcote 1995, p. 156), while
those from lake populations migrate downstream (inlet spawners) or
upstream (outlet spawners) to the adjacent lake. Following spawning,
adults move to appropriate feeding areas if they are not adjacent to
spawning habitat (Armstrong 1986, pp. 7-8; Shepard and Oswald 1989; p.
18). Juvenile Arctic grayling may undertake seasonal migrations between
feeding and overwintering habitats until they reach maturity and add
the spawning migration to this cycle (Northcote 1995, pp. 156-157).
Life History Diversity in Arctic Grayling in the Upper Missouri River
Basin
Two general life-history forms or ecotypes of native Arctic
grayling occur in the upper Missouri River Arctic: Fluvial and
adfluvial. Fluvial fish use river or stream (lotic) habitat for all of
their life cycles and may undergo extensive migrations within river
habitat, up to 50 miles in the Big Hole River in Montana (Shepard and
Oswald 1989, p. 18). Adfluvial fish live in lakes and migrate to
tributary streams to spawn. These same life-history forms also are
expressed by Arctic grayling elsewhere in North America (Northcote
1997, p. 1030). Historically, the fluvial life-history form
predominated in the Missouri River basin above the Great Falls, perhaps
because there were only a few lakes accessible to natural colonization
of Arctic grayling that would permit expression of the
[[Page 49392]]
adfluvial ecotype (Kaya 1992, p. 47). The fluvial and adfluvial life-
history forms of Arctic grayling in the upper Missouri River do not
appear to represent distinct evolutionary lineages. Instead, they
appear to represent an example of adaptive radiation (Schluter 2000, p.
1), whereby the forms differentiated from a common ancestor and
developed traits that allowed them to exploit different habitats. The
primary evidence for this conclusion is genetic data that indicate that
within the Missouri River basin the two ecotypes are more closely
related to each other than they are to the same ecotype elsewhere in
North America (Redenbach and Taylor 1999, pp. 27-28; Stamford and
Taylor 2004, p. 1538; Peterson and Ardren 2009, p. 1766). Historically,
there may have been some genetic exchange between the two life-history
forms as individuals strayed or dispersed into different populations
(Peterson and Ardren 2009, p. 1770), but the genetic structure of
current populations in the upper Missouri River basin is consistent
with reproductive isolation.
The fluvial and adfluvial forms of Arctic grayling appear to differ
in their genetic characteristics, but there appears to be some
plasticity in behavior where individuals from a population can exhibit
a range of behaviors. Arctic grayling fry in Montana can exhibit
heritable, genetically-based differences in swimming behavior between
fluvial and adfluvial ecotypes (Kaya 1991, pp. 53, 56-58; Kaya and
Jeanes 1995, pp. 454, 456). Progeny of Arctic grayling from the fluvial
ecotype exhibited a greater tendency to hold their position in flowing
water relative to progeny from adfluvial ecotypes (Kaya 1991, pp. 53,
56-58; Kaya and Jeanes 1995, pp. 454, 456). Similarly, young Arctic
grayling from inlet and outlet spawning adfluvial ecotypes exhibited an
innate tendency to move downstream and upstream, respectively (Kaya
1989, pp. 478-480). All three studies (Kaya 1989, entire; 1991, entire;
Kaya and Jeanes 1995, entire) demonstrate that the response of fry to
flowing water depended strongly on the life-history form (ecotype) of
the source population, and that this behavior has a genetic basis.
However, behavioral responses also were mediated by environmental
conditions (light--Kaya 1991, pp. 56-57; light and water temperature--
Kaya 1989, pp. 477-479), and some progeny of each ecotype exhibited
behavior characteristic of the other; for example some individuals from
the fluvial ecotype moved downstream rather than holding position, and
some individuals from an inlet-spawning adfluvial ecotype held position
or moved upstream (Kaya 1991, p. 58). These observations indicate that
some plasticity for behavior exists, at least for very young Arctic
grayling.
The ability of the fluvial ecotype to give rise to a functional
population of the adfluvial ecotype has been demonstrated. Most extant
adfluvial Arctic grayling populations in the Upper Missouri River
originated from fluvial-dominated sources (see Table 1; Kaya 1992, p.
53; Jeanes 1996, pp. 54). However, the ability of the adfluvial ecotype
to give rise to a functional population of fluvial ecotype is less
certain. Circumstantial support for reduced plasticity in adfluvial
Arctic grayling comes from observations that adfluvial fish stocked in
river habitats almost never establish populations (Kaya 1990, pp. 31-
34). However, we note that adfluvial Arctic grayling retain some life-
history flexibility--at least in lake environments--as naturalized
populations derived from inlet-spawning stocks have established outlet-
spawning demes (a deme is a local populations that shares a distinct
gene pool) in Montana and in Yellowstone National Park (Kruse 1959, p.
318; Kaya 1989, p. 480). In addition, a small percentage of young
adfluvial Arctic grayling exposed to flow exhibited fluvial-like
characteristics (e.g., station-holding or upstream movement) in a
laboratory experiment designed to assess movement tendencies of
adfluvial and fluvial Arctic grayling in flowing water (Kaya 1991, p.
56). These results indicate some plasticity exists in adfluvial Arctic
grayling that may allow some progeny of adfluvial individuals to
express a fluvial life history. Nonetheless, the frequent failure of
introductions of adfluvial Arctic grayling into fluvial habitats
suggest a cautionary approach to the loss of particular life-history
forms is warranted.
Age and Growth
Age at maturity and longevity in Arctic grayling varies regionally
and is probably related to growth rate, with populations in colder,
northern latitudes maturing at later ages and having a greater lifespan
(Kruse 1959, pp. 340-341; Northcote 1995 and references therein, pp.
155-157). Arctic grayling in the upper Missouri River typically mature
at age 2 (males) or age 3 (females), and individuals greater than age 6
are rare (Kaya 1990, p. 18; Magee and Lamothe 2003, pp. 16-17). The
majority of the Arctic grayling spawning in two tributaries in the
Centennial Valley, Montana, were age 3, and the oldest individuals aged
from a larger sample were age 6 (Nelson 1954, pp. 333-334). Arctic
grayling spawning in Red Rock Creek were mostly ages 2 to 5, but some
individuals were age 7 (Mogen 1996, pp. 32-34).
Generally, growth rates of Arctic grayling are greatest during the
first years of life then slow dramatically after maturity. Within that
general pattern, there is substantial variation among populations from
different regions. Arctic grayling populations in Montana (Big Hole
River and Red Rock Lakes) have very high growth rates relative to those
from British Columbia, Asia, and the interior and North Slope of Alaska
(Carl et al. 1992, p. 240; Northcote 1995, pp. 155-157; Neyme 2005, p.
28).
Distinct Vertebrate Population Segment
Under the Service's Policy Regarding the Recognition of Distinct
Vertebrate Population Segments Under the Endangered Species Act (61 FR
4722; February 7, 1996), three elements are considered in the decision
concerning the establishment and classification of a possible DPS.
These are applied similarly for additions to or removal from the
Federal List of Endangered and Threatened Wildlife. These elements
include:
(1) The discreteness of a population in relation to the remainder
of the species to which it belongs;
(2) The significance of the population segment to the species to
which it belongs; and
(3) The population segment's conservation status in relation to the
Act's standards for listing, delisting, or reclassification (i.e., is
the population segment endangered or threatened).
Discreteness
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.
Arctic grayling native to the upper Missouri River are isolated
from all other populations of the species, which inhabit the Arctic
Ocean, Hudson Bay, and north Pacific Ocean drainages in
[[Page 49393]]
Asia and North America. Arctic grayling native to the upper Missouri
River occur as a disjunct group of populations approximately 800 km
(500 mi) to the south of the next-nearest Arctic grayling population in
central Alberta, Canada. Missouri River Arctic grayling have been
isolated from other populations for at least 10,000 years based on
historical reconstruction of river flows at or near the end of the
Pleistocene (Cross et al. 1986, p. 375; Pileou 1991, pp. 10-11).
Genetic data confirm Arctic grayling in the Missouri River basin have
been reproductively isolated from populations to the north for
millennia (Everett 1986, pp. 79-80; Redenbach and Taylor 1999, p. 23;
Stamford and Taylor 2004, p. 1538; Peterson and Ardren 2009, pp. 1764-
1766; USFWS, unpublished data). Consequently, we conclude that Arctic
grayling native to the upper Missouri River are markedly separated from
other native populations of the taxon as a result of physical factors
(isolation), and therefore meet the first criterion of discreteness
under the DPS policy. As a result, Arctic grayling native to the upper
Missouri River are considered a discrete population according to the
DPS policy. Because the entity meets the first criterion (markedly
separated), an evaluation with respect to the second criterion
(international boundaries) is not needed.
Significance
If a population segment is considered discrete under one or more of
the conditions described in the Service's DPS policy, its biological
and ecological significance will be considered in light of
Congressional guidance that the authority to list DPSs 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 surviving natural occurrence of a taxon that may be more abundant
elsewhere as an introduced population outside its historical 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.
Unique Ecological Setting
Water temperature is a key factor influencing the ecology and
physiology of ectothermic (body temperature regulated by ambient
environmental conditions) salmonid fishes, and can dictate reproductive
timing, growth and development, and life-history strategies.
Groundwater temperatures can be related to air temperatures (Meisner
1990, p. 282), and thus reflect the regional climatic conditions.
Warmer groundwater influences ecological factors such as food
availability, the efficiency with which food is converted into energy
for growth and reproduction, and ultimately growth rates of aquatic
organisms (Allan 1995, pp. 73-79). Aquifer structure and groundwater
temperature is important to salmonid fishes because groundwater can
strongly influence stream temperature, and consequently egg incubation
and fry growth rates, which are strongly temperature-dependent (Coutant
1999, pp. 32-52; Quinn 2005, pp. 143-150).
Missouri River Arctic grayling occur within the 4 to 7 [deg]C (39
to 45 [deg]F) ground water isotherm (see Heath 1983, p. 71; an isotherm
is a line connecting bands of similar temperatures on the earth's
surface), whereas most other North American Arctic grayling are found
in isotherms less than 4 [deg]C, and much of the species' range is
found in areas with discontinuous or continuous permafrost (Meisner et
al. 1988, p. 5; Table 2). Much of the historical range of Arctic
grayling in the upper Missouri River is encompassed by mean annual air
temperature isotherms of 5 to 10 [deg]C (41 to 50 [deg]F) (USGS 2009),
with the colder areas being in the headwaters of the Madison River in
Yellowstone National Park. In contrast, Arctic grayling in Canada,
Alaska, and Asia are located in regions encompassed by air temperature
isotherms 5 [deg]C and colder (41 [deg]F and colder), with much of the
species distributed within the 0 to -10 [deg]C isolines (32 to 14
[deg]F). This difference is significant because Arctic grayling in the
Missouri River basin have evolved in isolation for millennia in a
generally warmer climate than other populations. The potential for
thermal adaptations makes Missouri River Arctic grayling a significant
biological resource for the species under expected climate change
scenarios.
Table 2--Differences Between the Ecological Setting of the Upper
Missouri River and Elsewhere in the Species' Range of Arctic Grayling
------------------------------------------------------------------------
Ecological setting variable Missouri River Rest of taxon
------------------------------------------------------------------------
Bailey's Ecoregion.......... Dry Domain: Polar Domain: Tundra &
Temperate Subarctic Humid
Steppe. Temperate: Marine,
Prairie, Warm
Continental Mountains.
Air temperature (isotherm).. 5 to 10 [deg]C -15 to 5 [deg]C (5 to 41
(41 to 50 [deg]F).
[deg]F).
Groundwater temperature 4 to 7 [deg]C Less than 4 [deg]C (Less
(isotherm). (39 to 45 than 39 [deg]F).
[deg]F).
------------------------------------------------------------------------
Arctic grayling in the upper Missouri River basin occur in a
temperate ecoregion distinct from all other Arctic grayling populations
worldwide, which occur in Arctic or sub-Arctic ecoregions dominated by
Arctic flora and fauna. An ecoregion is a continuous geographic area
within which there are associations of interacting biotic and abiotic
features (Bailey 2005, pp. S14, S23). These ecoregions delimit large
areas within which local ecosystems recur more or less in a predictable
fashion on similar sites (Bailey 2005, p. S14). Ecoregional
classification is hierarchical, and based
[[Page 49394]]
on the study of spatial coincidences, patterning, and relationships of
climate, vegetation, soil, and landform (Bailey 2005, p. S23). The
largest ecoregion categories are domains, which represent
subcontinental areas of similar climate (e.g., polar, humid temperate,
dry, and humid tropical) (Bailey 1994; 2005, p. S17). Domains are
divided into divisions that contain areas of similar vegetation and
regional climates. Arctic grayling in the upper Missouri River basin
are the only example of the species naturally occurring in a dry domain
(temperate steppe division; Table 2). The vast majority of the species'
range is found in the polar domain (all of Asia, most of North
America), with small portions of the range occurring in the humid
temperate domain (northern British Columbia and southeast Alaska).
Occupancy of Missouri River Arctic grayling in a temperate ecoregion is
significant for two primary reasons. First, an ecoregion represents a
suite of factors (climate, vegetation, landform) influencing, or
potentially influencing, the evolution of species within that
ecoregion. Since Missouri River Arctic grayling have existed for
thousands of years in an ecoregion quite different from the majority of
the taxon, they have likely developed adaptations during these
evolutionary timescales that distinguish them from the rest of the
taxon, even if we have yet to conduct the proper studies to measure
these adaptations. Second, the occurrence of Missouri River Arctic
grayling in a unique ecoregion helps reduce the risk of species-level
extinction, as the different regions may respond differently to
environmental change.
Arctic grayling in the upper Missouri River basin have existed for
at least 10,000 years in an ecological setting quite different from
that experienced by Arctic grayling elsewhere in the species' range.
The most salient aspects of this different setting relate to
temperature and climate, which can strongly and directly influence the
biology of ectothermic species (like Arctic grayling). Arctic grayling
in the upper Missouri River have experienced warmer temperatures than
most other populations. Physiological and life-history adaptation to
local temperature regimes are regularly documented in salmonid fishes
(Taylor 1991, pp. 191-193), but experimental evidence for adaptations
to temperature, such as unusually high temperature tolerance or lower
tolerance to colder temperatures, is lacking for Missouri River Arctic
grayling because the appropriate studies have not been conducted. Lohr
et al. (1996, p. 934) studied the upper thermal tolerances of Arctic
grayling from the Big Hole River, but their research design did not
include other populations from different thermal regimes, so it was not
possible to make between-population contrasts under a common set of
conditions. Arctic grayling from the upper Missouri River demonstrate
very high growth rates relative to other populations (Northcote 1995,
p. 157). Experimental evidence obtained by growing fish from
populations under similar conditions would be needed to measure the
relative influence of genetics (local adaptation) versus environment.
We conclude that the occurrence of Arctic grayling in the upper
Missouri River is biogeographically important to the species, that
grayling there have occupied a warmer and more temperate setting that
is distinctly different from the ecological settings relative to the
rest of the species (see Table 2, above), and that they have been on a
different evolutionary trajectory for at least 10,000 years. We
conclude that these differences are significant because they may
provide the species with additional evolutionary resiliency in the
future in light of the changing climate. Consequently, we believe that
Arctic grayling in the upper Missouri River occupy a unique ecological
setting for the species.
Gap in the Range
Arctic grayling in Montana (southern extent is approximately
44[deg]36'23'' N latitude) represent the southern-most extant
population of the species' distribution since the Pleistocene
glaciation. The next-closest native Arctic grayling population outside
the Missouri River basin is found in the Pembina River (approximately
52[deg]55'6.77'' N latitude) in central Alberta, Canada, west of
Edmonton (Blackburn and Johnson 2004, pp. ii, 17; ASRD 2005, p. 6). The
Pembina River drains into Hudson Bay and is thus disconnected from the
Missouri River basin. Loss of the native Arctic grayling of the upper
Missouri River would shift the southern distribution of Arctic grayling
by more than 8[deg] latitude (about 500 miles). Such a dramatic range
constriction would constitute a significant geographic gap in the
species' range and would eliminate a genetically distinct group of
Arctic grayling, which may limit the species' ability to cope with
future environmental change.
Marginal populations, defined as those on the periphery of the
species' range, are believed to have high conservation significance
(Mitikka et al. 2008; Gibson et al. 2009, entire; Haak et al. 2010,
entire; Osborne et al. 2012). Peripheral populations may occur in
suboptimal habitats and thus be subjected to very strong selective
pressures (Fraser 2000, p. 50). Consequently, individuals from these
populations may contain adaptations that may be important to the taxon
in the future. Lomolino and Channell (1998, p. 482) hypothesize that
because peripheral populations should be adapted to a greater variety
of environmental conditions, then they may be better suited to deal
with anthropogenic (human-caused) disturbances than populations in the
central part of a species' range. Arctic grayling in the upper Missouri
River have, for millennia, existed in a climate warmer than that
experienced by the rest of the taxon. If this selective pressure has
resulted in adaptations to cope with increased water temperatures, then
the population segment may contain genetic resources important to the
taxon. For example, if northern populations of Arctic grayling are less
suited to cope with increased water temperatures expected under climate
warming, then Missouri River Arctic grayling might represent an
important population for reintroduction in those northern regions. We
believe that Arctic grayling's occurrence at the southernmost extreme
of the range in the upper Missouri River contributes to the resilience
of the overall taxon because these peripheral populations may possess
increased adaptability relative to the rest of the taxon.
Only Surviving Natural Occurrence of the Taxon That May Be More
Abundant Elsewhere as an Introduced Population Outside of Its
Historical Range
This criterion does not directly apply to the Arctic grayling in
the upper Missouri River because it is not the only surviving natural
occurrence of the taxon; there are native Arctic grayling populations
in Canada, Alaska, and Asia.
Differs Markedly in Its Genetic Characteristics
Differences in genetic characteristics can be measured at the
molecular, genetic, or phenotypic level. Three different types of
molecular markers (allozymes, mtDNA, and microsatellites) demonstrate
that Arctic grayling from the upper Missouri River are genetically
different from those in Canada, Alaska, and Asia (Everett 1986, pp. 79-
80; Redenbach and Taylor 1999, p. 23; Stamford and Taylor 2004, p.
1538; Peterson and Ardren 2009, pp. 1764-1766; USFWS, unpublished
data). These
[[Page 49395]]
data confirm the reproductive isolation among populations that
establishes the discreteness of Missouri River Arctic grayling under
the DPS policy. Here, we speak to whether these data also establish
significance.
Allozymes
Using allozyme data, Everett (1986, entire) found marked genetic
differences among Arctic grayling collected from the Chena River in
Alaska; those descended from fish native to the Athabasca River
drainage in the Northwest Territories, Canada; and native upper
Missouri River drainage populations or populations descended from them
(see Leary 2005, pp. 1-2). The Canadian population had a high frequency
of two unique alleles (forms of a gene), which strongly differentiated
them from all the other samples (Everett 1986, p. 44). With the
exception of one introduced population in an irrigation canal
(Sunnyslope canal) in Montana that is believed to have experienced
extreme genetic bottlenecks, the Chena River (Alaskan) fish were highly
divergent from all the other samples as they possessed an unusually low
frequency of a specific allele (Everett 1986, p. 60; Leary 2005, p. 1),
and contained a unique variant of another allele (Leary 2005, p. 1).
Overall, each of the four native Missouri River populations examined
(Big Hole, Miner, Mussigbrod, and Centennial Valley) exhibited
statistically significant differences in allele frequencies relative to
both the Chena River (Alaska) and Athabasca River (Canada) populations
(Everett 1986, pp. 15, 67).
Combining the data of Everett (1986, entire), Hop and Gharrett
(1989, entire), and Leary (1990, entire) provides information from 21
allozyme loci (genes) from five native upper Missouri River drainage
populations, five native populations in the Yukon River drainage in
Alaska, and the one population descended from the Athabasca River
drainage in Canada (Leary 2005, pp. 1-2). Examination of the genetic
variation in these samples indicated that most of the genetic
divergence is due to differences among drainages (29 percent) and
comparatively little (5 percent) results from differences among
populations within a drainage (Leary 2005, p. 1).
Mitochondrial DNA
Analysis using mtDNA indicates that Arctic grayling in North
America represent at least three evolutionary lineages that are
associated with distinct glacial refugia (Redenbach and Taylor 1999,
entire; Stamford and Taylor 2004, entire). Arctic grayling in the upper
Missouri River basin belong to the so-called North Beringia lineage
(Redenbach and Taylor 1999, pp. 27-28; Samford and Taylor 2004, pp.
1538-1540) because they possess a form of mtDNA that was generally
absent from populations collected from other locations within the
species' range in North America (Redenbach and Taylor 1999, pp. 27-28;
Stamford and Taylor 2004, p. 1538). The notable exceptions were that
some fish from the lower Peace River drainage in British Columbia,
Canada, and all sampled individuals from the Saskatchewan River
drainage Saskatchewan, Canada, also possessed this form of mtDNA
(Stamford and Taylor 2004, p. 1538).
A form of mtDNA common in upper Missouri River Arctic grayling,
which occurs at lower frequencies in other populations, indicates that
Arctic grayling native to the upper Missouri River drainage probably
originated from a glacial refuge in the drainage and subsequently
migrated northwards when the Missouri River temporarily flowed into the
Saskatchewan River and was linked to an Arctic drainage (Cross et al.
1986, pp. 374-375; Pielou 1991, p. 195). When the Missouri River began
to flow southwards because of the advance of the Laurentide ice sheet
(Cross et al. 1986, p. 375; Pileou 1991, p. 10), the Arctic grayling in
the drainage became physically and reproductively isolated from the
rest of the species' range (Leary 2005, p. 2; Campton 2004, p. 6),
which would have included those populations in Saskatchewan.
Alternatively, the Missouri River Arctic grayling could have
potentially colonized Saskatchewan or the Lower Peace River (in British
Columbia) or both post-glacially (Stamford 2001, p. 49) via a gap in
the Cordilleran and Laurentide ice sheets (Pielou 1991, pp. 10-11),
which also might explain the low frequency 'Missouri River'' mtDNA in
Arctic grayling in the Lower Peace River and Upper Yukon River.
We do not interpret the observation that Arctic grayling in Montana
and Saskatchewan, and to lesser extent those from the Lower Peace and
Upper Yukon River systems, share a mtDNA haplotype to mean that these
groups of fish are genetically identical. Rather, we interpret it to
mean that these fish shared a common ancestor tens to hundreds of
thousands of years ago.
Microsatellite DNA
Recent analysis of microsatellite DNA (highly variable portions of
nuclear DNA) showed substantial divergence between Arctic grayling in
Missouri River and Saskatchewan populations (Peterson and Ardren 2009,
entire). This divergence between populations was measured in terms of
allele frequencies, using a metric called Fst (Allendorf and Luikart
2007, pp. 52-54, 198-199). An analogous metric, named Rst, also
measures genetic differentiation between populations based on
microsatellite DNA, but differs from Fst in that it also considers the
size differences between alleles (Hardy et al. 2003, p. 1468). An Fst
or Rst of 0 indicates that populations are the same genetically,
whereas a value of 1 indicates the populations share no genetic
material at the markers being surveyed. Fst values range from 0.13 to
0.31 (average 0.18) between Missouri River and Saskatchewan populations
(Peterson and Ardren 2009, pp. 1758, 1764-1765), whereas Rst values
range from 0.47 to 0.71 (average 0.54) for the same comparisons
(Peterson and Ardren 2009, pp. 1758, 1764-1765). These values indicate
that the two populations differ significantly in allele frequency and
also in the size of those alleles. This outcome indicates that the
observed genetic differences are due to mutational differences, which
suggests the groups may have been separated for millennia (Peterson and
Ardren 2009, pp. 1767-1768).
Analysis of Arctic grayling populations from Alaska, Canada, and
the Missouri River basin using nine of the same microsatellite loci as
Peterson and Ardren (2009, entire) further supports the distinction of
Missouri River Arctic grayling relative to populations elsewhere in
North America (USFWS, unpublished data). This analysis clearly
separated sample fish from 21 populations into two clusters: One
cluster representing populations from the upper Missouri River basin,
and another cluster representing populations from across Canada and
Alaska (USFWS, unpublished data). Divergence in size among these
alleles further supports the distinction between Missouri River Arctic
grayling and those in Canada and Alaska (USFWS, unpublished data). The
interpretation of these data is that the Missouri River populations and
the Canada/Alaska populations are highly genetically distinct at the
microsatellite loci considered.
Phenotypic Characteristics Influenced by Genetics--Meristics
Phenotypic variation can be evaluated by counts of body parts
(i.e., meristic counts of the number of gill rakers, fin rays, and
vertebrae characteristics of a population) that can vary within and
among species. These meristic traits are influenced by both genetics
and the environment (Allendorf and Luikart
[[Page 49396]]
2007, pp. 258-259). When the traits are controlled primarily by genetic
factors, then meristic characteristics can indicate significant genetic
differences among groups. Arctic grayling north of the Brooks Range in
Alaska and in northern Canada had lower lateral line scale counts than
those in southern Alaska and Canada (McCart and Pepper 1971, entire).
These two scale-size phenotypes are thought to correspond to fish from
the North and South Beringia glacial refuges, respectively (Stamford
and Taylor 2004, p. 1545). Arctic grayling from the Centennial Valley
had a phenotype intermediate to the large- and small-scale types
(McCart and Pepper 1971, pp. 749, 754). Arctic grayling populations
from the Missouri River (and one each from Canada and Alaska) could be
correctly assigned to their group 60 percent of the time using a suite
of seven meristic traits (Everett 1986, pp. 32-35). Those native
Missouri River populations that had high genetic similarity also tended
to have similar meristic characteristics (Everett 1986, pp. 80, 83).
Arctic grayling from the Big Hole River showed marked differences
in meristic characteristics relative to two populations from Siberia,
and were correctly assigned to their population of origin 100 percent
of the time (Weiss et al. 2006, pp. 512, 515-516, 518). The populations
that were significantly different in terms of their meristic
characteristics also exhibited differences in molecular genetic markers
(Weiss et al. 2006, p. 518).
Inference Concerning Genetic Differences in Arctic Grayling of the
Missouri River Relative to Other Examples of the Taxon
We believe the differences between Arctic grayling in the Missouri
River and sample populations from Alaska and Canada measured using
allozymes (Everett 1986, entire; Leary 2005, entire), mitochondrial DNA
(Redenbach and Taylor 1999, entire; Stamford and Taylor 2004, entire),
and microsatellite DNA markers (Peterson and Ardren 2009, pp. 1764-
1766; USFWS, unpublished data) represent ``marked genetic differences''
in terms of the extent of differentiation (e.g., Fst,
Rst) and the importance of that genetic legacy to the rest
of the taxon. The presence of morphological characteristics separating
Missouri River Arctic grayling from other populations also likely
indicates genetic differences, although this conclusion is based on a
limited number of populations (Everett 1986, pp. 32-35; Weiss et al.
2006, entire), and we cannot entirely rule out the influence of
environmental variation.
The intent of the DPS policy and the Act is to preserve important
elements of biological and genetic diversity, not necessarily to
preserve the occurrence of unique alleles in particular populations. In
Arctic grayling of the Missouri River, the microsatellite DNA data
indicate that the group is evolving independently from the rest of the
species. The extirpation of this group would mean the loss of the
genetic variation in one of the two most distinct groups identified in
the microsatellite DNA analysis, and the loss of the future
evolutionary potential that goes with it. Thus, the genetic data
support the conclusion that Arctic grayling of the upper Missouri River
represent a unique and irreplaceable biological resource of the type
the Act was intended to preserve. Thus, we conclude that Missouri River
Arctic grayling differ markedly in their genetic characteristics
relative to the rest of the taxon.
Upper Missouri River Arctic grayling satisfy the significance
criteria outlined in the Services' DPS policy because they occur in a
unique ecological setting, are separated from other Arctic grayling
populations by a large gap in their range, and differ markedly in their
genetic characteristics relative to other Arctic grayling populations.
Therefore, we consider the Arctic grayling in the upper Missouri River
basin significant to the taxon to which it belongs under the Service's
DPS policy.
Determination of Distinct Population Segment
We find that a population segment that includes all native ecotypes
of Arctic grayling in the upper Missouri River basin satisfies the
discreteness standard of the DPS policy. The segment is physically
isolated, and genetic data indicate that Arctic grayling in the
Missouri River basin have been separated from other populations for
thousands of years. The population segment occurs in an isolated
geographic area far south of all other Arctic grayling populations
worldwide, and we find that loss of this population segment would
create a significant gap in the species' range. Molecular genetic data
clearly differentiate Missouri River Arctic grayling from other Arctic
grayling populations, including those in Canada and Alaska.
Based on the best scientific and commercial information available,
as described above, we find that, under the Service's DPS policy, upper
Missouri River Arctic grayling are discrete and are significant to the
taxon to which they belong. Because the upper Missouri River population
of Arctic grayling is both discrete and significant, it qualifies as a
DPS under the Act.
As we described above, we are including introduced Arctic grayling
populations that occur in lakes in the upper Missouri River basin as
part of the DPS. The Service has interpreted the Act to provide a
statutory directive to conserve species in their native ecosystems (49
FR 33885; August 27, 1984) and to conserve genetic resources and
biodiversity over a representative portion of a taxon's historical
occurrence (61 FR 4722; February 7, 1996). The introduced Arctic
grayling populations occur within the boundaries of the upper Missouri
River basin and represent moderate to high levels of genetic diversity
from within the basin. The future adaptive capabilities represented by
this genetic diversity have conservation value, particularly given a
changing climate.
We define the historical range of this population segment to
include the major streams, lakes, and tributary streams of the upper
Missouri River (mainstem Missouri, Smith, Sun, Beaverhead, Jefferson,
Big Hole, and Madison Rivers, as well as their key tributaries, as well
as a few small lakes where Arctic grayling are or were believed to be
native (Elk Lake, Red Rock Lakes in the Centennial Valley, Miner Lake,
and Mussigbrod Lake, all in Beaverhead County, Montana)). We define the
current range of the DPS to consist of extant native populations in the
Big Hole River, Miner Lake, Mussigbrod Lake, Madison River-Ennis
Reservoir, and Centennial Valley, as well as all known introduced
populations within the upper Missouri River basin. We refer to this
entity as the Upper Missouri River DPS of Arctic grayling. The
remainder of this finding will thus focus on the population status of
and potential threats to this entity.
Population Status and Trends of Populations in the Upper Missouri River
DPS
The Upper Missouri River DPS of Arctic grayling is comprised of 20
populations, including 2 fluvial populations and 16 adfluvial
populations. Two other populations (Centennial Valley and Madison
River/Ennis Reservoir) appear to exhibit both fluvial and adfluvial
components (Table 3). Arctic grayling from the Centennial Valley (Long
Creek) and Ennis Reservoir/Madison River (mainstem Madison River) have
been documented well past the spawning period through autumn. These
occurrences are more prevalent in Long Creek in the Centennial Valley
than in the Madison
[[Page 49397]]
River population and do not appear to be linked to individual Arctic
grayling seeking thermal refugia during summer (Montana Arctic Grayling
Workgroup (AGW) 1995; p. 1; Cayer 2014a, pers. comm.; MFISH 2014b,
unpublished data). These occurrences include multiple age classes (Age-
1 to Age-3) of Arctic grayling in both Long Creek and the Madison River
and are located in stream reaches that are considerable distances (up
to 15 miles in the Madison River) from adfluvial habitats (Cayer 2014a,
pers. comm.; MFISH 2014b, unpublished data). Eighteen of the 20
populations occur solely on Federal or majority Federal land; the
remaining two (Big Hole River and Ennis Reservoir/Madison River) occur
on primarily private land.
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Estimated abundance of reproductively mature individuals in the two
fluvial populations varies from about one hundred to several thousand
[[Page 49399]]
Arctic grayling (Table 3). Where quantitative data are available,
estimated abundance of mature individuals in adfluvial populations
(including the two populations exhibiting both life histories) varies
from a few hundred to around 25,000 Arctic grayling. Most populations
are currently stable or increasing in abundance, with the exception of
the Ennis Reservoir/Madison River population (Table 3).
Distinct Population Segment Five-Factor Analysis
Since the Arctic grayling in the upper Missouri River basin
qualifies as a DPS, we will now evaluate its status with regard to its
potential for listing as endangered or threatened based on the five
factors enumerated in section 4(a) of the Act. Our evaluation of the
Upper Missouri River DPS of Arctic grayling follows.
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR 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 this finding, information pertaining to the Upper
Missouri River DPS of Arctic grayling in relation to the five factors
provided in section 4(a)(1) of the Act is discussed below. 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 an endangered or threatened species under the
Act.
In making our revised 12-month finding on the petition, we consider
and evaluate the best available scientific and commercial information.
This evaluation includes all factors we previously considered in the
2010 finding and, at the end of this analysis, explains how the
Services' conclusions differ now.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Curtailment of Range and Distribution
The range and distribution of fluvial Arctic grayling in the upper
Missouri River basin was reduced over the past 100 years (Kaya 1992, p.
51), primarily due to historical habitat fragmentation by dams and
irrigation diversions and by habitat degradation or modification from
unregulated land use (Vincent 1962, pp. 97-121). Fluvial Arctic
grayling typically need large expanses of connected habitat to fulfill
their life-history stages (Armstrong 1986, p. 8). For example, fluvial
Arctic grayling in the Big Hole River have been documented migrating
over 60 miles (97 km) between overwintering, spawning, and foraging
habitats (Shepard and Oswald 1989, pp. 18-21, 27). These past
reductions in range and distribution reproductively isolated fluvial
Arctic grayling populations within the basin (Peterson and Ardren 2009,
p. 1770).
Although the range and distribution of fluvial Arctic grayling has
contracted from historical levels, expression of the fluvial life
history is represented, at least in part, in four Arctic grayling
populations within the Upper Missouri River DPS. Whether strictly
fluvial (e.g., Big Hole and Ruby River) or partially fluvial (e.g.,
Centennial Valley (Long Creek) and Ennis Reservoir/Madison River
(mainstem Madison River)), these populations occur in four watersheds
where large reaches of connected habitat remain and still permit the
expression of the fluvial life history, despite the presence of
mainstem dams in three of four watersheds (Kaya 1992, entire; see
Figure 1). Thus, despite historical curtailment of range, the amount of
connected habitat in some systems is adequate to permit the expression
of the fluvial life history.
Of the four Arctic grayling populations still expressing a fluvial
life history, three of four populations (Big Hole River, Centennial
Valley, and Ruby River) are currently increasing in abundance (see
Table 3). In each of these populations, as abundance increases, there
is a corresponding increase in distribution. Natural reproduction is
occurring in all three of these populations. In the Big Hole River and
the Centennial Valley, remote site incubators (RSIs) have been used as
a conservation tool to help facilitate increased abundance and
distribution of Arctic grayling. Thus, observed increases in abundance
and distribution may be partially attributable to the use of RSIs (for
more in-depth discussion on RSI use, see ``Native Arctic Grayling
Genetic Reserves and Translocation,'' below). Given the above
information, it appears that three of four fluvial, or partly fluvial,
populations are viable and have the necessary configuration and amount
of habitat to fulfill their life-history needs. Thus, effects of past
range curtailment on the fluvial component of Arctic grayling in the
upper Missouri River basin are present, but there appears to be
sufficient adequate habitat remaining to support expression of the
fluvial life history.
Adfluvial Arctic grayling populations in the upper Missouri River
basin are present in all lakes originally thought to have had native
populations historically (Miner, Mussigbrod, Upper Red Rock, and Elk
Lakes (present but not included in Table 3, above, because of uncertain
viability)). Thus, there has been no contraction of the range of
adfluvial populations. Given the above information, curtailment of
range and distribution is not precluding the expression of either
fluvial or adfluvial life history. Although curtailment of range and
distribution occurred historically, Arctic grayling populations are
still present in 7 of 10 historically occupied watersheds in the upper
Missouri River basin (see ``Drainage'' column in Table 3). Accordingly,
we have no evidence that curtailment of range and distribution is a
current threat to the DPS. In addition, we have no information
suggesting curtailment of range and distribution will be a threat in
the future.
Dams on Mainstem Rivers
Much of the historical range of the Upper Missouri River DPS of
Arctic
[[Page 49400]]
grayling has been altered by the construction of dams and reservoirs
(Kaya 1990, pp. 51-52; Kaya 1992, p. 57). The construction of large
dams on mainstem river habitats throughout the upper Missouri River
system fragmented river corridors necessary for the expression of
Arctic grayling migratory life histories in some systems. Construction
of dams that obstructed fish passage on the mainstem Missouri River
(Hauser, Holter, Canyon Ferry, and Toston dams), Madison River
(Madison-Ennis, Hebgen dams), Beaverhead River and its tributary Red
Rock River (Clark Canyon, Lima dams), Ruby River (Ruby dam), and Sun
River (Gibson dam) all likely contributed to the historical decline of
fluvial Arctic grayling in the DPS (Vincent 1962, pp. 127-128; Kaya
1992, p. 57). Lack of fish passage at these dams contributed to the
extirpation of fluvial Arctic grayling from some waters by blocking
migratory corridors (Vincent 1962, p. 128), curtailing access to
important spawning and rearing habitats, and impounding water over
former spawning locations (Vincent 1962, p. 128). Most dams within the
upper Missouri River basin were constructed between 1905 and 1960 (Kaya
1990, entire).
Despite the construction of multiple dams throughout the historical
range of Arctic grayling, multiple populations, or portions of
populations, of the fluvial ecotype are still represented in the DPS.
These populations reside in areas where sufficient quantity and quality
of habitat exist and permit the expression of this life history. In
some cases, dams may be providing a benefit, because currently many of
the dams that historically affected fluvial Arctic grayling populations
are now precluding invasion by nonnative fish from downstream sources.
For example, Lima Dam in the Centennial Valley is currently precluding
brown trout invasion from downstream sources (Mogen 2014, pers. comm).
Currently, there are five Arctic grayling populations within the DPS
that occur above mainstem dams (Centennial Valley, Ruby River, Hyalite
Lake, Diversion Lake, and Gibson Reservoir) with at least one nonnative
fish species occurring downstream of these dams (MFISH 2014d,
unpublished data).
Some reservoirs created by dams are currently being used by Arctic
grayling as overwintering, rearing and foraging areas. Both adult and
juvenile Arctic grayling use Ennis Reservoir for overwintering,
rearing, and foraging (Byorth and Shepard 1990, entire). In the
Centennial Valley, Arctic grayling have recently been detected in Lima
Reservoir (MFISH 2014e, unpublished data). The movements of Arctic
grayling within and out of Lima Reservoir are unknown; however, Lima
Reservoir is a large reservoir and, as such, is likely used for
overwintering purposes.
Arctic grayling have been documented in stream and river reaches
below some dams, most likely indicating downstream passage of fish over
or through dams. These fish are essentially ``lost'' to the population
residing above the dam, because none of the mainstem river dams in the
upper Missouri River basin provides upstream fish passage. Substantial
losses from a population resulting from downstream entrainment of fish
through dams could cause declines in reproductive potential and
abundance in the reservoir population above the dam (Kimmerer 2008,
entire). However, it is unknown what entrainment rates currently are in
populations residing near dams. Rate of entrainment is likely dependent
on a number of factors, including dam operations, season, water
conditions in the reservoir, initial population size above the dam,
etc. Recent monitoring data and angler reports of Arctic grayling
observed downstream of reservoirs supporting Arctic grayling
populations are sporadic (Horton 2014c, pers. comm.; SSA 2014); thus it
appears the threat of mainstem dams is likely affecting some
individuals, but not affecting populations or the DPS as a whole.
Historically, operational practices at Madison Dam have likely
affected the Arctic grayling population in Ennis Reservoir/Madison
River. A population decline in Arctic grayling appeared to coincide
with a reservoir drawdown in the winter of 1982-1983 (Byorth and
Shepard 1990, pp. 52-53). This drawdown likely affected the forage
base, rearing habitat, and spawning cycle of Arctic grayling in the
reservoir. However, under a new licensing agreement dated September 27,
2000, between the Federal Energy Regulatory Commission and Ennis Dam
operators, such substantial drawdowns in elevation of Ennis Reservoir
are no longer permitted (Clancey 2014, pers. comm.).
Given the above information, mainstem dams were a historical threat
to Arctic grayling populations in the upper Missouri River basin. Dams
still impact individuals, because some Arctic grayling are currently
being entrained and lost from their source population. In Ennis
Reservoir, the new licensing agreement is expected to reduce the
effects of dam operations on the Arctic grayling population. Most
Arctic grayling populations residing above dams are stable or
increasing; thus, it does not appear this impact is acting at the
population or DPS level. We have no information to conclude that
mainstem dams will be a threat in the future at the population or DPS
level.
Water Management in the Upper Missouri River Basin
The predominant use of private lands in the upper Missouri River
basin is irrigated agriculture and ranching. These activities have
historically had significant effects on aquatic habitats, primarily
changes in water availability and alteration of the structure and
function of aquatic habitats. Changes in water availability can affect
Arctic grayling reproduction, survival, and movements among habitat
types (Kaya 1990, entire).
In contrast to most of the Arctic grayling populations in the Upper
Missouri River DPS that occur on Federal land, the fluvial population
of Arctic grayling in the Big Hole River occurs on primarily (~90
percent) private land. Thus, any conservation efforts conducted in the
Big Hole River Valley need support from involved agencies and private
landowners. In 2006, a candidate conservation agreement with assurances
(CCAA; Montana Fish, Wildlife, and Parks et al. 2006, entire) was
developed for Arctic grayling in the Big Hole River. The conservation
goal of this CCAA is to secure and enhance the fluvial population of
Arctic grayling in the upper Big Hole River drainage. Conservation
projects conducted under the CCAA are prioritized and guided by the Big
Hole Arctic Grayling Strategic Habitat Conservation Plan (SHCP) (for
more specific information, see ``Conservation Efforts to Reduce Habitat
Destruction, Modification, or Curtailment of Its Range,'' below).
Since 2006, many conservation and restoration projects have been
completed in the upper Big Hole River under the direction of the CCAA
and SHCP (Table 4). Below, we describe and evaluate the implementation
and effectiveness of these projects relative to the potential stressors
analyzed under Factor A for the Big Hole River population. We also
analyze the effects of potential stressors under Factor A for the other
Arctic grayling populations in the DPS.
[[Page 49401]]
Table 4--Conservation Projects and Results, and Arctic Grayling Response in the Big Hole River Since
Implementation of the Big Hole CCAA in 2006
[All information on conservation projects and conservation results cited from the Big Hole Arctic Grayling
Strategic Habitat Conservation Plan]
----------------------------------------------------------------------------------------------------------------
Conservation projects Arctic grayling
Threat factor Stressor \a\ Conservation result response
----------------------------------------------------------------------------------------------------------------
A..................... Dams/habitat Fish ladders: 41..... Stream miles (%) Number of
fragmentation. Bridges: 7........... accessible to breeding adults has
Grade control grayling \b\: increased from ~100
structures: 2. Tier I- (2007-2011) to 500-
82(98%; pre- 900 \c\ (2013)
CCAA=87%).. (Leary 2014,
Tier II- unpublished data).
61(67%; pre-
CCAA=27%)..
Tier III-
32(20%: pre-
CCAA=6%)..
Dewatering/Thermal PODs: 343 of 504 with Arctic
stress. signed SSPs. Achievement of grayling abundance
Irrigation instream flow \d\ (catch per unit
improvements: 88. goals increased effort) increased
Water measuring from 50% (pre- from 0.2 fish/mile
devices: 67. CCAA) to 78% (2008) to 1.4 fish/
Stock water systems: (post-CCAA). mile (2012) in the
63. Landowner CCAA monitoring
Stream restoration: contributions to reaches of the
26 miles. streamflow mainstem Big Hole
Rock Creek increasing as River (MFWP 2013a,
restoration. of PODs unpublished data).
with signed SSPs
increase [landowner
contribution to
instream flows in
Big Hole River (pre-
2006 = 0 cfs; 2013
= 250 cfs)].
Temperature
reductions in
tributaries (see
Rock Creek example
below).
Pre-restoration Arctic
(2007):. grayling abundance
36 days \d\ (catch per unit
max. temp >70 effort) increased
[deg]F. from 2.9 fish/mile
16 days (2008) to 7.4 fish/
max. temp >77 mile (2012) in the
[deg]F. CCAA monitoring
Post-restoration tributaries (MFWP
(2013):. 2013a, unpublished
0 days max data).
temp. >70 [deg]F. Arctic
grayling
distribution has
increased 4 miles
in Rock Creek
(young-of-year and
Age 1+) and 2 miles
in Big Lake Creek
(Age 1+) since 2006
(SHCP 2013, p. 12).
Entrainment........... Fish screens: 2...... No
Prioritized entrainment
monitoring protocol. documented since
2010.
Observed low
entrainment rates in
unscreened ditches
(73 Arctic grayling/
138 ditch miles).
Riparian habitat loss. Stream restoration: 110 miles
26 miles. (65%) of riparian
Riparian fencing: 108 habitat on enrolled
miles. lands improving.
Stock water systems: 15% increase
63. in sustainable
Grazing mgmt. plans: riparian areas from
21 landowners 32% (2006) to 47%
(85,000 ac.). (2013).
Noxious weed Adaptive
management. management in place
Willow planting to address non-
(72,200 planted). improving areas.
----------------------------------------------------------------------------------------------------------------
\a\ PODs = Points of Diversion, SSPs = Site-specific plans; \b\ Tier I is core spawning, rearing and adult
habitat that is currently occupied by Arctic grayling, Tier II is periphery habitat intermittently used by
Arctic grayling, Tier III is suitable, but currently unoccupied historical habitat; \c\ The estimate of number
of breeding adults in the Big Hole River in 2013 is reported as a range because of uncertainty in the
frequency rate of rare alleles in the analysis; \d\ Abundance estimates from 2013 were lower than those
reported for 2012 likely due to unusually high flows (3X normal) concurrent with fall sampling that likely
decreased capture efficiency, resulting in lower abundance estimates in 2013.
[[Page 49402]]
Habitat Fragmentation/Smaller Seasonal Barriers
Big Hole River: Smaller dams or diversions associated with
irrigation structures historically posed a threat to Arctic grayling
migratory behavior, especially in the Big Hole River drainage. In the
Big Hole River, numerous diversion structures have been identified as
putative fish migration barriers (Petersen and Lamothe 2006, pp. 8, 12-
13, 29) that may limit the ability of Arctic grayling to migrate to
spawning, rearing, or sheltering habitats under certain conditions. As
with the larger dams, these smaller fish passage barriers can reduce
reproduction (access to spawning habitat is blocked), reduce growth
(access to feeding habitat is blocked), and increase mortality (access
to refuge habitat is blocked). Historically, these types of barriers
were numerous and widespread across the Big Hole River drainage.
Currently, habitat fragmentation due to irrigation diversion
structures in the Big Hole is being systematically reduced under the
CCAA for Fluvial Arctic Grayling in the upper Big Hole River
(hereafter, Big Hole CCAA or CCAA; for more specific information, see
``Conservation Efforts to Reduce Habitat Destruction, Modification, or
Curtailment of Its Range'') and Big Hole Arctic Grayling SHCP. Since
2006, 41 fish ladders have been installed in the mainstem Big Hole
River and tributaries (Table 4). Multiple culverts have been replaced
with bridges and several grade control structures have been installed
(Table 4). As a result, no fish barriers now exist in the mainstem
upper Big Hole River. Almost all (98 percent) of tier I habitat and the
majority (68 percent) of tier II habitat is connected and accessible to
Arctic grayling (Table 4): 67 miles of stream have been reconnected in
the Big Hole River system since 2006 (MFWP 2014a, unpublished data).
Other populations: Smaller fish passage barriers also have been
noted to affect Arctic grayling in the Centennial Valley (Unthank 1989,
p. 9). Historically, spawning Arctic grayling migrated from the
Jefferson River system, through the Beaverhead River and Red Rock River
through the Red Rock Lakes and into the upper drainage, and then
returned downstream after spawning (Henshall 1907, p. 5). The
construction of a water control structure (sill) at the outlet of Lower
Red Rock Lake in 1930 (and reconstruction in 1957 (USFWS 2009, p. 74))
created an upstream migration barrier that blocked these migrations
(Unthank 1989, p. 10; Gillin 2001, p. 4-4). However, recent changes in
water management at the Red Rock Lakes National Wildlife Refuge (NWR)
have resulted in year-round fish passage through the control structure
at the outlet of Lower Red Rock Lake (West 2013, pers. comm.).
In Mussigbrod Lake, Arctic grayling occasionally pass downstream
over a diversion structure at the lake outlet, and become trapped in an
isolated pool (Olsen 2014, pers. comm.). During high-snowpack years,
Arctic grayling likely can swim back up to the lake from the pool, but
in low snowpack years, some Arctic grayling perish when the isolated
pool dries up (Olsen 2014, pers. comm.). However, this phenomenon has
occurred periodically in recent history and has had no discernible
impacts on Arctic grayling abundance in Mussigbrod Lake (Olsen 2014,
pers. comm.).
All 16 adfluvial Arctic grayling populations in the upper Missouri
River basin occur on Federal land (U.S. Forest Service) and are not
influenced by irrigation structures because none are present. The
effect of a barrier at the outlet of Mussigbrod Lake is likely
impacting individuals, but not the population because of the robust
population size in Mussigbrod Lake and historical stability of that
population since the outlet structure was created. Based on this
information, we conclude that the threats from habitat fragmentation
have been sufficiently mitigated or minimized and are no longer are
acting as a stressor at the population or DPS level.
Degradation of Riparian Habitat
Riparian corridors are important for maintaining habitat for Arctic
grayling in the upper Missouri River basin, and in general are critical
for the ecological function of aquatic systems (Gregory et al. 1991,
entire). Riparian zones are important for Arctic grayling because of
their effect on water quality and water temperature, and their role in
maintaining natural ecological process responsible for creating and
maintaining necessary physical habitat features (i.e., pools, riffles,
and scour areas) used by the species to meet its life-history
requirements.
Big Hole: Arctic grayling abundance in the upper Big Hole River is
positively related to the presence of overhanging vegetation, primarily
willows (Salix spp.), that is associated with pool habitat (Lamothe and
Magee 2004, pp. 21-22). Removal of willows and riparian clearing
concurrent with livestock and water management along the upper Big Hole
River has led to a shift in channel form (i.e., braided channels
becoming a single wide channel), increased erosion rates, reduced
cover, increased water temperatures, and reduced recruitment of large
wood debris into the active stream channel (Confluence Consulting et
al. 2003, pp. 24-26). These factors combine to reduce the suitability
of the habitat for species like Arctic grayling (Hubert 1985, entire).
Currently, restoration of riparian areas in the upper Big Hole
River system is a priority under the CCAA (for more specific
information, see ``Conservation Efforts to Reduce Habitat Destruction,
Modification, or Curtailment of Its Range,'' below). Since 2006,
efforts to restore and conserve riparian habitats have been numerous
and multi-faceted (see Table 4). About 170 miles (274 km) of riparian
habitat are currently enrolled in the Big Hole CCAA, out of a total of
about 340 miles (547 km) of total riparian habitat in the CCAA
Management Area. Of the enrolled riparian habitat, 65 percent (110
miles (177 km)) is improving in condition, as rated by a standardized
riparian protocol (NRCS 2004, entire). Further, 47 percent of enrolled
riparian habitat (80 miles (129 km)) is functioning at a sustainable
level, which is a 15 percent increase in 5 years (MTFWP et al. 2006, p.
92; see Table 4). A sustainable rating indicates that the stream can
access its flood plain, transport its sediment load, build banks, store
water, and dissipate flood energy in conjunction with a healthy
riparian zone (NRCS 2004, p. 7). Riparian habitats are reassessed every
5 years and are scored on 10 stability and sustainability metrics (for
example, stream incisement), with any reach scoring at 80 percent or
above rated as sustainable (NRCS 2004, entire). In addition, adaptive
management within the CCAA framework will allow for reevaluation of
conservation measures being implemented in non-improving habitat.
Other populations: In the Centennial Valley, historical livestock
grazing both within the Red Rock Lakes NWR and on adjacent private
lands negatively affected the condition of riparian habitats on
tributaries to the Red Rock Lakes (Mogen 1996, pp. 75-77; Gillin 2001,
pp. 3-12, 3-14). In general, degraded riparian habitat limits the
creation and maintenance of aquatic habitats, especially pools, which
are preferred habitats for adult Arctic grayling (Lamothe and Magee
2004, pp. 21-22; Hughes 1992, entire), although many spawning adult
Arctic grayling in Red Rock Creek outmigrate soon after spawning and
likely do not use available pool habitat (Jordan 2014, pers. comm.).
Loss of riparian vegetation
[[Page 49403]]
increases bank erosion, which can lead to siltation of spawning
gravels, which may in turn harm Arctic grayling by reducing the extent
of suitable spawning habitat and reducing survival of Arctic grayling
embryos already present in the stream gravels.
Recently, the Red Rock Lakes NWR acquired land on Red Rock Creek,
upstream of the refuge boundary (West 2014a, pers. comm.). Much of this
parcel was riparian habitat that was historically heavily grazed; thus,
the refuge implemented a rest-rotation grazing system where more
durable lands are grazed while more sensitive lands (e.g., riparian
areas) are rested for up to 4 years. On average, grazing intensities on
the refuge have decreased from 20,000 Animal Unit Months (AUMs, number
of cow/calf pairs multiplied by the number of months grazed) to about
5,000 AUMs. As a result of these changes, riparian habitat within the
refuge has dramatically improved (West 2014b, pers. comm.) and is
expected to continue improving under the new grazing regime. Concurrent
with riparian improvement within Red Rock Lakes NWR, the number of
adult Arctic grayling migrating up Red Rock Creek to spawn has
increased from fewer than 500 to more than 2,000 (Patterson 2014,
unpublished data). Given the riparian improvements within Red Rock
Lakes NWR, and that the refuge represents the vast majority of current
Arctic grayling habitat in the Centennial Valley, the effects of
degraded riparian habitat do not appear to be acting on the core of the
Centennial Valley population at the individual or population level.
Most of the riparian habitat surrounding high-elevation lakes on
Federal land where the remaining populations are found is intact and of
high quality (MFISH 2014a, unpublished data; MFWP 2014e, unpublished
data; USFS 2014, p. 2), because these habitats are in remote locations
or wilderness areas with little anthropogenic disturbance. Given that
riparian degradation is being systematically addressed in the Big Hole
River and Centennial Valley on the National Refuge land where the
majority of Arctic grayling reside, we conclude that riparian
degradation is not a current threat to the DPS. Riparian habitat is
expected to remain intact on Federal land because of existing
regulatory mechanisms (see in Factor D discussion, below). Riparian
habitat in the Big Hole River is expected to continue improving because
of the proven track record of conservation evidenced by the current
upward trend in riparian habitat quality. As more site-specific plans
are signed under the Big Hole CCAA, more riparian improvement is
expected because conservation measures will be similar between
currently implemented and future site-specific plans. Given that
riparian habitat is intact or improving for populations of Arctic
grayling occurring on Federal land and the Big Hole population, and
these populations account for 19 of 20 populations in the DPS, we
conclude riparian habitat degradation is not a current rangewide threat
and is not expected to become a threat in the future.
Dewatering From Irrigation and Consequent Increased Water Temperatures
Demand for irrigation water in the semi-arid upper Missouri River
basin historically dewatered many rivers formerly or currently occupied
by Arctic grayling. The primary effects of this dewatering were: (1)
Increased water temperatures, and (2) reduced habitat capacity. In
ectothermic species like salmonid fishes, water temperature sets basic
constraints on species' distribution and physiological performance,
such as activity and growth (Coutant 1999, pp. 32-52). Increased water
temperatures can reduce the growth and survival of Arctic grayling
(physiological stressor). Reduced habitat capacity can concentrate
fishes and thereby increase competition and predation (ecological
stressor). Below we discuss the potential effects of increased water
temperature on the Upper Missouri River DPS of Arctic grayling. For
discussion of the potential effects of reduced habitat capacity, see
Cumulative Effects from Factors A through E, below.
Big Hole: In the Big Hole River system, surface-water (flood)
irrigation has altered the natural hydrologic function of the river
(Shepard and Oswald 1989, p. 29; Byorth 1993, p. 14; 1995, pp. 8-10;
Magee et al. 2005, pp. 13-15). An inverse relationship between flow
volume and water temperature (i.e., lower flows can lead to higher
water temperatures) is apparent in the Big Hole River (Flynn et al.
2008, pp. 44, 46, but see Sladek 2013, p. 31). Summer water
temperatures exceeding 21 [deg]C (70 [deg]F) are considered to be
physiologically stressful for cold-water fish species, such as Arctic
grayling (Hubert et al. 1985, pp. 7, 9). Summer water temperatures
consistently exceed 21 [deg]C (70 [deg]F) in the mainstem of Big Hole
River (Cayer and McCullough 2012, p. 7; (Cayer and McCullough 2013, p.
6) and have exceeded the upper incipient lethal temperature (UILT; the
temperature that is survivable for periods longer than 1 week by 50
percent of a ``test population'' in an experimental setting) for Arctic
grayling (e.g., 25 [deg]C or 77 [deg]F) (Lohr et al. 1996). As a
result, thermal fish kills have been documented in the Big Hole River
(Lohr et al. 1996, p. 934) in the past. The most recent fish kill in
the Big Hole River that we are aware of occurred in 1994, and included
eight fish species, including Arctic grayling (Lohr et al. 1996, p.
934).
Arctic grayling in the Big Hole River use tributaries as a thermal
refuge when summer water temperatures in the mainstem become stressful
(Vatland et al. 2009, p. 11). Summer water temperatures within most
tributaries are cooler than those observed in some reaches of the
mainstem Big Hole River (Vatland et al. 2009, entire; MFWP 2014b,
unpublished data).
Since 2006, water conservation and restoration projects associated
with the Big Hole Arctic grayling CCAA (for more specific information,
see ``Conservation Efforts to Reduce Habitat Destruction, Modification,
or Curtailment of Its Range,'' below) have been implemented to increase
instream flows and reduce water temperatures in the Big Hole River and
tributaries. Varying flow targets for different management segments of
the Big Hole River were outlined in the CCAA, based on the wetted
perimeter method, a biologically based method for determining instream
flow requirements to provide necessary resources for all life stages of
Arctic grayling. Over 300 irrigation diversions are operated under flow
agreements within finalized site-specific plans (Table 4). The 10
remaining site-specific plans representing the remainder of points of
diversion are expected to be signed in August 2014. Although we are
aware of the future potential of more points of diversion being managed
under signed site plans to contribute to Arctic grayling conservation,
we do not consider these anticipated future efforts to contribute to
Arctic grayling conservation currently, and have not considered them as
part of this status review or our listing determination for this DPS.
Multiple other projects designed to decrease dewatering and thermal
stress have been implemented since 2006 (Table 4). The collective
result of these efforts are increasing streamflows, increased access to
cold-water refugia via fish ladders, and marked temperature reductions,
particularly in some tributaries (Table 4).
Specific flow targets were developed for the different Management
Segments in the CCAA Management Area (see MFWP et al. 2006, pp. 7, 9,
13, for more information on CCAA Management
[[Page 49404]]
Segments). The goal for increasing instream flow was to achieve flow
targets 75 percent of days in each Management Segment during years of
average or greater snowpack. This goal was based on a comparison
between minimum flow targets and historical streamflows recorded in
Management Segments C and D. Achieving flow targets 75 percent of days
in each Management Segment was intended to be a general goal because
many other factors influence instream flows in the Big Hole River that
are outside the control of landowners (e.g., snowpack, precipitation).
Before implementation of the CCAA (2000-2005), average flow targets
were met among all Management Segments 50 percent of the time, and
since implementation of the CCAA (2006-2012), they have been met 78
percent of the time (SHCP 2013, p. 12). Thus, the targets are being
met.
Consistently since 2006, one management area, known as Management
Segment C, has exhibited the lowest instream flows among all Management
Segments. In part, instream flows in Management Segment C are
influenced by several large diversions immediately upstream of the flow
measuring device at the downstream boundary of Management Segment C
(Robert 2014, pers. comm.). Some of this diverted water is returned to
the Big Hole River downstream of the flow measuring device (Robert
2014, pers. comm.). As such, instream flows in Management Segment C
represent the ``worst case'' scenario among all Management Segments.
The Montana Department of Natural Resources and Conservation conducted
an analysis of this ``worst case'' scenario, to explore how instream
flows in Management Segment C have changed since the inception of the
Big Hole CCAA. Given that natural factors such as summer precipitation
and annual snowpack influence instream flows in the Big Hole River, the
analysis of instream flows in Management Segment C included comparisons
among several years of similar (but below average) snow pack and
similar summer precipitation, both before and after CCAA implementation
(Table 5).
Table 5--Comparison of Number of Days Varying Flow Targets Were Achieved
Among Similar Years of Below Average Snowpack in the Big Hole River CCAA
Management Segment C, Pre- and Post CCAA. All Information in This Table
Cited From Roberts 2014, Unpublished Data
------------------------------------------------------------------------
Pre-CCAA Post-CCAA
-----------------------------------
1988 2003 2012 2013
------------------------------------------------------------------------
Peak snowpack (percent of average).. \a\73 108 81 \a\75
May-Aug. precipitation (in.)........ 4.14 3.85 4.74 5.14
July-Aug. temps (degrees F; -1.3 8.0 1.4 1.9
departure from normal).............
Signed SSPs......................... 0 0 12 15
Landowner contributions (cfs)....... 0 0 252 260
Days <160 \b\ cfs................... 50 8 11 40
Days <60 \b\ cfs.................... 123 123 87 69
Days <20 cfs........................ 79 68 0 28
Days <10 cfs........................ 65 7 0 1
Mean discharge (cfs; July-Sept.).... 8.4 19.7 45 39
Mean discharge (cfs; Aug.).......... 1.1 14.2 33.7 21
-----------------------------------
Total Days 60 years) with no observed declines in abundance.
Predation by Birds and Mammals
In general, the incidence and effect of predation by birds and
mammals on Arctic grayling is not well understood because few detailed
studies have been completed (Northcote 1995, p. 163). Black bear (Ursus
americanus), mink (Neovison vison), and river otter (Lontra canadensis)
are present in southwestern Montana, but direct evidence of predatory
activity by these species is often lacking (Kruse 1959, p. 348). Osprey
(Pandion haliaetus) can capture Arctic grayling during the summer
(Kruse 1959, p. 348). In the Big Hole River, Byorth and Magee (1998, p.
926) attributed the loss of Arctic grayling from artificial enclosures
used in a competition experiment to predation by minks, belted
kingfisher (Ceryle alcyon), osprey, and great blue heron (Ardea
herodia). In addition, American white pelican (Pelecanus
erythrorhynchos) are seasonally present in the Big Hole River, and they
also may feed on Arctic grayling. The aforementioned mammals and birds
can be effective fish predators; however, Arctic grayling evolved with
these native predator species and have developed life-history and
reproductive strategies to mitigate for predation losses. We have no
data demonstrating any of these species historically or currently
consume Arctic grayling at levels sufficient to exert a measureable,
population-level impact on native Arctic grayling in the upper Missouri
River system. We expect the current situation to continue, so we
conclude that predation by birds and mammals does not constitute a
threat to Missouri River Arctic grayling now or in the future.
Summary of Factor C
Based on the information available at this time, we conclude
disease does not represent a past or current threat to the Upper
Missouri River DPS of Arctic grayling. We have no basis for concluding
that disease may become a future threat.
Predation and competition can influence the distribution,
abundance, and diversity of species in ecological communities.
Predation by and competition with nonnative species can negatively
affect native species, particularly those that are stressed or
occurring at low densities due to unfavorable environmental conditions.
Historically, the impact of predation and competition from nonnatives
was likely greater because many of the habitats used by Arctic grayling
were degraded. Thus, predation and competition likely played a role
historically in decreasing the abundance and distribution of Arctic
grayling. Currently, habitat conditions have improved markedly for
those Arctic grayling populations on Federal land (18 of 20
populations) and for the Big Hole River population on primarily private
land. Predation and competition with nonnative species are still
occurring in these systems, although the extent and magnitude of these
effects appears to be mediated by habitat quality. Abundance of Arctic
grayling and nonnative brown trout are increasing in the Big Hole
River. Before suppression efforts began, Yellowstone cutthroat hybrids
and Arctic grayling spawners were both at 40 year highs in Red Rock
Creek in the Centennial Valley. We acknowledge nonnative trout
densities are high in the Madison River and may be contributing to the
decline of that Arctic grayling population; however, most other
adfluvial populations appear to have stable abundance of Arctic
grayling and nonnatives. Thus, based on our review we have no
information that predation or competition represents a threat at the
DPS level on the Upper Missouri River DPS of Arctic grayling. Further,
Arctic grayling experts project only a small effect of predicted
nonnative trout densities on Arctic grayling recruitment in the future.
Thus, we have no information that predation or competition from
nonnative trout represents a future threat at the population or species
level.
Little is known about the effect of predation on Arctic grayling by
birds and mammals. Such predation likely does occur, but we are not
aware of any situation where an increase in fish-eating birds or
mammals has coincided with the decline of Arctic grayling.
Consequently, the available information does not support a conclusion
that predation by birds or mammals represents a substantial past,
present, or future threat to native Arctic grayling in the upper
Missouri River.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Section 4(b)(1)(A) of the Act requires the Service to take into
account ``those efforts, if any, being made by any State or foreign
nation, or any political subdivision of a State or foreign nation, to
protect such species . . .'' We consider relevant Federal, State, and
Tribal laws, and regulations when evaluating the status of the species.
Regulatory mechanisms, if they exist, may preclude the need for listing
if we determine that such mechanisms adequately address the threats to
the species such that listing is not warranted. Only existing
ordinances, regulations, and laws, that have a direct connection to a
law, are enforceable and permitted are discussed in this section. All
other measures are discussed under the specific relevant factor.
U.S. Federal Laws and Regulations
No Federal laws in the United States specifically address the
Arctic grayling, but several, in their implementation, may affect the
species' habitat.
National Environmental Policy Act
All Federal agencies are required to adhere to the National
Environmental Policy Act (NEPA) of 1970 (42 U.S.C. 4321 et seq.) for
projects they fund, authorize, or carry out. The Council on
Environmental Quality's regulations for implementing NEPA (40 CFR parts
1500-1518) state that, when preparing environmental impact statements,
agencies shall include a discussion on the environmental impacts of the
various project alternatives, any adverse environmental effects which
cannot be avoided, and any irreversible or irretrievable commitments of
resources involved (40 CFR part 1502). The NEPA itself is a disclosure
law, and does not require subsequent minimization or mitigation
measures by the Federal agency involved. Although Federal agencies may
include conservation measures for Arctic grayling as a result of the
NEPA process, any such measures are typically voluntary in nature and
are not required by NEPA.
[[Page 49415]]
Federal Land Policy and Management Act
The Federal Land Policy and Management Act (FLPMA) of 1976 (43
U.S.C. 1701 et seq.), as amended, states that the public lands shall be
managed in a manner that will protect the quality of scientific,
scenic, historical, ecological, environmental, air and atmospheric,
water resource, and archeological values. This statute protects lands
within the range of the Arctic grayling managed by the Bureau of Land
Management (BLM).
The BLM considers the fluvial Arctic grayling a sensitive species
requiring special management consideration for planning and
environmental analysis (BLM 2009a, entire, BLM 2009b, entire). The BLM
has recently developed a resource management plan (RMP) for the Dillon
Field Office Area that provides guidance for the management of over
900,000 acres of public land administered by BLM in southwest Montana
(BLM 2006a, p. 2). The Dillon RMP area thus includes the geographic
area that contains the Big Hole, Miner, Mussigbrod, Madison River, and
Centennial Valley populations of Arctic grayling. A RMP planning area
encompasses all private, State, and Federal lands within a designated
geographic area (BLM 2006a, p. 2), but the actual implementation of the
RMP focuses on lands administered by the BLM that typically represent
only a fraction of the total land area within that planning area (BLM
2006b, entire). Restoring Arctic grayling habitat and ensuring the
long-term persistence of both fluvial and adfluvial ecotypes are among
the RMP's goals (BLM 2006a, pp. 30-31). However, there is little actual
overlap between the specific parcels of BLM land managed by the Dillon
RMP and the current distribution of Arctic grayling (BLM 2006b,
entire).
The BLM also has a RMP for the Butte Field Office Area, which
includes more than 300,000 acres in south-central Montana (BLM 2008,
entire), including portions of the Big Hole River in Deerlodge and
Silver Bow counties (BLM 2008, p. 8; 2009c, entire). The Butte RMP
considers conservation and management strategies and agreements for
Arctic grayling in its planning process and includes a goal to
opportunistically enhance or restore habitat for Arctic grayling (BLM
2008, pp. 10, 30, 36). However, the Butte RMP does not mandate specific
actions to improve habitat for Arctic grayling in the Big Hole River
and little overlap exists between BLM-managed lands and Arctic grayling
occupancy in this planning area.
National Forest Management Act
Under the U.S. Forest Service (USFS) National Forest Management Act
(NFMA) of 1976, as amended (16 U.S.C. 1600 et seq.), the USFS strives
to provide for a diversity of plant and animal communities when
managing national forest lands. Individual national forests may
identify species of concern that are significant to each forest's
biodiversity. The USFS considers fluvial Arctic grayling a sensitive
species (USFS 2004, entire) for which population viability is a
concern. However, this designation provides no special regulatory
protections.
Most of the upper Missouri River grayling populations occur on
National Forest land; all 16 adfluvial populations and the fluvial Ruby
River population (majority on National Forest) occur on USFS-managed
lands. These populations occur across four different National Forests;
consequently the riparian habitats surrounding the lakes and
tributaries are managed according to the standards and guidelines
outlined in each National Forest Plan. All Forest Plans do not contain
the same standards and guidelines; however, each Plan has standards and
guidelines for protecting riparian areas around perennial water
sources. In the Beaverhead-Deerlodge and Helena National Forest Plans,
the Inland Native Fish Strategy (INFS) standards and guidelines have
been incorporated. The INFS, in part, defines widths of riparian buffer
zones adequate to protect streams and lakes from non-channelized
sediment inputs and contribute to other riparian functions, such as
stream shading and bank stability. These protections have been
incorporated into the Beaverhead-Deerlodge and Helena National Forest
Plans through amendments and are currently preserving intact riparian
areas around most, if not all, adfluvial Arctic grayling habitats.
Exceptions to the riparian protections outlined in INFS are
occasionally granted; however, these exceptions require an analysis of
potential effects and review by a USFS fish biologist.
On the Gallatin National Forest, standards and guidelines in the
Forest Plan include using ``best management practices (BMPs)'' to
protect water sources and riparian areas. Similar to INFS, BMPs outline
buffer strips along watercourses where disturbance and activity is
minimized to protect riparian areas and water quality. On the Lewis and
Clark National Forest, standards and guidelines are in place to leave
timbered buffer strips adjacent to waterbodies to protect riparian
areas. Grayling habitat on the Gallatin and Lewis and Clark National
Forests consists of seven high-elevation mountain lakes.
The NFMA and INFS are adequately protecting riparian habitat on
National Forest land, given the intact nature of most riparian areas
surrounding the high-elevation lake populations and the Ruby River.
National Park Service (NPS) Organic Act
The NPS Organic Act of 1916 (16 U.S.C. 1 et seq.), as amended,
states that the NPS ``shall promote and regulate the use of the Federal
areas known as national parks, monuments, and reservations . . . to
conserve the scenery and the national 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.'' Arctic grayling are native to the
western part of Yellowstone National Park and habitats are managed
accordingly for the species under the Native Species Management Plan
(NPS 2010, entire). One adfluvial Arctic grayling population, Grebe
Lake, currently occurs in Yellowstone National Park. The Grebe Lake
population is one of the larger adfluvial populations (see Table 3,
above) in the DPS. The habitat in Grebe Lake and the tributaries is
managed for conservation (NPS 2010, p. 44). Further, it is expected
that these habitats will be managed for conservation in the future,
based on provisions in the Organic Act and guidance outlined in the
Native Species Management Plan.
National Wildlife Refuge System Improvement Act of 1997
The National Wildlife Refuge Systems Improvement Act (NWRSIA) of
1997 (Pub. L. 105-57) amends the National Wildlife Refuge System
Administration Act of 1966 (16 U.S.C. 668dd et seq.). The NWRSIA
directs the Service to manage the Refuge System's lands and waters for
conservation. The NWRSIA also requires monitoring of the status and
trends of refuge fish, wildlife, and plants. The NWRSIA requires
development of a comprehensive conservation plan (CCP) for each refuge
and management of each refuge consistent with its plan.
The Service has developed a final CCP to provide a foundation for
the management and use of Red Rock Lakes NWR (USFWS 2009, entire) in
the Centennial Valley. Since the development of the CCP, Refuge staff
have conducted numerous habitat conservation/restoration projects to
benefit Arctic grayling, including:
[[Page 49416]]
Removal of an earthen dam whose reservoir inundated several hundred
meters of historical Arctic grayling spawning habitat in Elk Springs
Creek, and subsequent reintroductions and tracking of young-of-year
Arctic grayling in Elk Springs Creek (West 2014a, pers. comm.). However
to date, the reintroductions in Elk Springs Creek have not established
a spawning run. Other conservation projects conducted on the Refuge
include the acquisition of new land and decreases in grazing
intensities from 20,000 AUMs to about 5,000 AUMs. The Refuge has
implemented a rest-rotation grazing system where more durable lands are
grazed while more sensitive lands (e.g., riparian areas) are rested for
up to 4 years (West 2014a, pers. comm.). Some active riparian
restoration has also occurred, including a project to reconnect Red
Rock Creek to a historical channel and replacement of four culverts to
allow for natural tributary migration across alluvial fans (West 2014a,
pers. comm.). The Refuge is also actively engaged in supporting ongoing
graduate research efforts to explore potential limiting factors for
Arctic grayling in the Centennial Valley.
Other conservation projects under the CCP have been focused on
potential nonnative species effects on Arctic grayling, namely a 5-year
project removing hybrid cutthroat trout captured during their upstream
spawning run and a study of dietary overlap between Arctic grayling and
Yellowstone cutthroat trout (West 2014a, pers. comm.). The Refuge also
operates a sill dam (previous upstream fish barrier) to provide
upstream fish passage and operates one irrigation ditch only when
snowpack is average or above and timing is such that young Arctic
grayling are not present near the diversion (West 2014a, pers. comm.).
The NWRSIA is adequately protecting habitat for Arctic grayling on
the Refuge because riparian habitats are improving and the Centennial
Valley population is increasing in both abundance and distribution. The
proven track record of completed conservation projects on the refuge
and currently expanding Arctic grayling population indicate that the
continued implementation of the CCP during the next 15 years (which is
the life of the CCP) will continue to improve habitat conditions on the
refuge.
Federal Power Act (FPA)
The Federal Power Act of 1920 (16 U.S.C. 791 et seq., as amended)
provides the legal authority for the Federal Energy Regulatory
Commission (FERC), as an independent agency, to regulate hydropower
projects. In deciding whether to issue a license, FERC is required to
give equal consideration to mitigation of damage to, and enhancement
of, fish and wildlife (16 U.S.C. 797(e)). A number of FERC-licensed
dams exist in the Missouri River basin in current (i.e., Ennis Dam on
the Madison River) and historical Arctic grayling habitat (e.g., Hebgen
Dam on the Madison River; Hauser, Holter, and Toston dams on the
mainstem Missouri River; and Clark Canyon Dam on the Beaverhead River).
The FERC license expiration dates for these dams range from 2024
(Toston) to 2059 (Clark Canyon) (FERC 2010, entire). None of these
structures provides upstream passage of fish, and such dams are
believed to be one of the primary factors that led to the historical
decline of Arctic grayling in the Missouri River basin (see discussion
under Factor A, above). However, recent monitoring data indicate
multiple stable Arctic grayling populations occurring above mainstem
dams, with the exception of the Ennis Reservoir/Madison River
population. The drawdowns in reservoir water level believed to have
historically affected the Ennis Reservoir/Madison River Arctic grayling
population are not permitted under a new licensing agreement between
the Federal Energy Regulatory Commission and Madison Dam operators, as
we described previously in this finding (Clancey 2014, pers. comm.).
This change in water management in Ennis Reservoir will ensure adequate
rearing and foraging habitat for this population. The fluvial ecotype
is still represented in the DPS and both strictly fluvial Arctic
grayling populations appear to be stable or increasing. Thus, we
conclude the Federal Power Act is currently adequate to protect the
Upper Missouri River DPS of Arctic grayling at the population and DPS
level.
Clean Water Act
The Clean Water Act (CWA) of 1972 (33 U.S.C. 1251 et seq.)
establishes the basic structure for regulating discharges of pollutants
into the waters of the United States and regulating quality standards
for surface waters. The CWA's general goal is to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters'' (33 U.S.C. 1251(a)). The CWA requires States to adopt
standards for the protection of surface water quality and establishment
of total maximum daily load (TMDL) guidelines for rivers. The Big Hole
River has approved TMDL plans for its various reaches (MDEQ 2009a,
entire; 2009b, entire); thus, complete implementation of this plan
should improve water quality (by reducing water temperatures, and
reducing sediment and nutrient inputs) in the Big Hole River in the
future. As of September 2013, there was no significant TMDL plan
development activity in the Madison River or Red Rock watershed in the
Centennial Valley (see MDEQ 2014). Currently, TMDL documents have been
approved for the Ruby River. All planning areas containing other
adfluvial Arctic grayling populations in the upper Missouri River basin
have approved TMDLs, including the Gallatin, Lake Helena, and Sun
watersheds (see MDEQ 2014).
Currently, water temperatures in the Big Hole River exceed levels
outlined in the TMDL. However, reductions in water temperature within
tributaries have been demonstrated (see discussion under Factor A and
Table 4). Given that most Arctic grayling populations within the upper
Missouri River basin are stable or increasing and habitats are largely
being managed in a manner that benefits the species, we have no
evidence that the CWA is inadequately protecting Arctic grayling at the
population or DPS level.
State Laws
Montana Environmental Policy Act
The legislature of Montana enacted the Montana Environmental Policy
Act (MEPA) as a policy statement to encourage productive and enjoyable
harmony between humans and their environment, to protect the right to
use and enjoy private property free of undue government regulation, to
promote efforts that will prevent or eliminate damage to the
environment and biosphere and stimulate the health and welfare of
humans, to enrich the understanding of the ecological systems and
natural resources important to the State, and to establish an
environmental quality council (MCA 75-1-102). Part 1 of the MEPA
establishes and declares Montana's environmental policy. Part 1 has no
legal requirements, but the policy and purpose provide guidance in
interpreting and applying statutes. Part 2 requires State agencies to
carry out the policies in Part 1 through the use of systematic,
interdisciplinary analysis of State actions that have an impact on the
human environment. This is accomplished through the use of a
deliberative, written environmental review. In practice, MEPA provides
a basis for the adequate review of State actions in order to ensure
that environmental concerns are fully considered (MCA 75-1-102).
Similar to NEPA, the MEPA is largely a disclosure
[[Page 49417]]
law and a decision-making tool that does not specifically require
subsequent minimization or mitigation measures.
Laws Affecting Physical Aquatic Habitats
A number of Montana State laws have a permitting process applicable
to projects that may affect stream beds, river banks, or floodplains.
These include the Montana Stream Protection Act (SPA), the Streamside
Management Zone Law (SMZL), and the Montana Natural Streambed and Land
Preservation Act (Montana Department of Natural Resources (MDNRC) 2001,
pp. 7.1-7.2). The SPA requires that a permit be obtained for any
project that may affect the natural and existing shape and form of any
stream or its banks or tributaries (MDNRC 2001, p. 7.1). The Montana
Natural Streambed and Land Preservation Act (i.e., MNSLPA or 310
permit) requires private, nongovernmental entities to obtain a permit
for any activity that physically alters or modifies the bed or banks of
a perennially flowing stream (MDNRC 2001, p. 7.1). The SPA and MNSLPA
laws do not mandate any special recognition for species of concern, but
in practice, biologists that review projects permitted under these laws
usually stipulate restrictions to avoid harming such species (Horton
2010, pers. comm.). The SMZL regulates forest practices near streams
(MDNRC 2001, p. 7.2). The Montana Pollutant Discharge Elimination
System (MPDES) Stormwater Permit applies to all discharges to surface
water or groundwater, including those related to construction,
dewatering, suction dredges, and placer mining, as well as to
construction that will disturb more than 1 acre within 100 ft (30.5 m)
of streams, rivers, or lakes (MDNRC 2001, p. 7.2).
Review of applications by MFWP, MTDEQ, or MDNRC is required prior
to issuance of permits under the above regulatory mechanisms (MDNRC
2001, pp. 7.1-7.2). These regulatory mechanisms are expected to limit
impacts to aquatic habitats in general. Given that most Arctic grayling
populations are stable or increasing in abundance in the presence of
these regulatory mechanisms, we have no basis for concluding that these
regulatory mechanisms are inadequate to protect the Arctic grayling and
their habitat now or in the future.
Montana Water Use Act
The purpose of the Montana Water Use Act (Title 85: Chapter 2,
Montana Codes Annotated) is to provide water for existing and future
beneficial use and to maintain minimum flows and water quality in
Montana's streams. The Missouri River system is generally believed to
be overappropriated, and water for additional consumptive uses is only
available for a few months during very wet years (MDNRC 1997, p. 12).
However, the upper Missouri River basin and Madison River basin have
been closed to new water appropriations because of water availability
problems, overappropriation, and a concern for protecting existing
water rights (MDNRC 2009, p. 45). In addition, recent compacts (a legal
agreement between Montana, a Federal agency, or an Indian tribe
determining the quantification of federally or tribally claimed water
rights) have been signed that close appropriations in specific waters
in or adjacent to Arctic grayling habitats. For example, the USFWS-Red
Rock Lakes-Montana Compact includes a closure of appropriations for
consumptive use in the drainage basins upstream of the most downstream
point on the Red Rock Lakes NWR and the Red Rock Lakes Wilderness Area
(MDNRC 2009, pp. 18, 47). The NPS-Montana Compact specifies that
certain waters will be closed to new appropriations when the total
appropriations reach a specified level, and it applies to Big Hole
National Battlefield and adjacent waters (North Fork of the Big Hole
River and its tributaries including Ruby and Trail Creeks), and the
portion of Yellowstone National Park that is in Montana (MDNRC 2009, p.
48).
The State of Montana is currently engaged in a Statewide effort to
adjudicate (finalize) water rights claimed before July 1, 1973. The
final product of adjudication in a river basin is a final decree. To
reach completion, a decree progresses through several stages: (1)
Examination, (2) temporary preliminary decree, (3) preliminary decree,
(4) public notice, (5) hearings, and (6) final decree (MDNRC 2009, pp.
9-14). As of February 2014, the Centennial Valley has a preliminary
decree, and the Big Hole and Madison Rivers have preliminary temporary
decrees (MDNRC 2014, entire). We anticipate the final adjudication of
all the river basins in Montana that currently contain native Arctic
grayling will be completed in the next 5 years, but we do not know if
this process will eliminate the overallocation of water rights. We note
that the overallocation of water in some systems within the upper
Missouri river basin is of general concern to Arctic grayling because
of the species' need for adequate quantity and quality of water for all
life stages. However, we have no information indicating that
overallocation of water in the upper Missouri River basin is a current
threat at the individual or DPS level because most populations are
stable or increasing at this time. Therefore, we conclude that the
Montana Water Use Act is adequate to protect the Arctic grayling and
its habitat.
Angling Regulations
Arctic grayling is considered a game fish (MFWP 2010, p. 16), but
is subject to special catch-and-release regulations in streams and
rivers within its native range, as was described under Factor B, above
(MFWP 2014d, p. 51). Catch-and-release regulations also are in effect
for Ennis Reservoir on the Madison River and Red Rock Creek in the
Centennial Valley (MFWP 2014d, p. 63). Arctic grayling in other
adfluvial populations are subject to more liberal regulations; anglers
can keep up to 5 per day and have up to 10 in possession in accordance
with standard daily and possession limits for that angling management
district (MFWP 2014d, p. 51). We have no evidence to indicate that
current fishing regulations are inadequate to protect native Arctic
grayling in the Missouri River basin (see discussion under Factor B,
above).
Summary of Factor D
Current Federal and State regulatory mechanisms are adequate to
protect Arctic grayling of the upper Missouri River. We conclude this
because the majority of populations are on Federal land where
regulatory mechanisms are in place to preserve intact habitats and are
expected to remain in place. In the Big Hole River, fluvial Arctic
grayling generally occupy waters adjacent to private lands (MFWP et al.
2006, p. 13; Lamothe et al. 2007, p. 4), so Federal regulations may
have limited ability to protect that population. However, some Federal
regulations (e.g., CWA, FPA, NMFA, NWRSIA, NPS Organic Act) in concert
with other existing conservation efforts (e.g., Big Hole CCAA) are
adequate to sustain and improve habitat conditions for Arctic grayling.
Arctic grayling in the Big Hole River appear to be responding
positively to these improvements. In addition, we did not identify
other threats to the DPS that would require regulatory protections.
For the reasons described above, we conclude that existing
regulatory mechanisms are adequate to protect the Upper Missouri River
DPS of Arctic grayling. We do not anticipate any changes to the
existing regulatory mechanisms; thus we conclude that existing
regulatory mechanisms will remain adequate in the future.
[[Page 49418]]
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Drought
Drought is a natural occurrence in the interior western United
States (see National Drought Mitigation Center 2010). The duration and
severity of drought in Montana appears to have increased during the
last 50 years, and precipitation has tended to be lower than average in
the last 20 years (National Climatic Data Center 2010). Drought can
affect fish populations by reducing stream flow volumes. This leads to
dewatering and high temperatures that can limit connectivity among
spawning, rearing, and sheltering habitats. Drought can also reduce the
volume of thermally suitable habitat and increase the frequency of
water temperatures above the physiological limits for optimum growth
and survival in Arctic grayling. In addition, drought can interact with
human-caused stressors (e.g., irrigation withdrawals, riparian habitat
degradation) to further reduce stream flows and increase water
temperatures.
Reduced stream flows and elevated water temperatures during drought
have been most apparent in the Big Hole River system (Magee and Lamothe
2003, pp. 10-14; Magee et al. 2005, pp. 23-25; Rens and Magee 2007, pp.
11-12, 14). In the Big Hole River, evidence for the detrimental effects
of drought on Arctic grayling populations is primarily inferential;
observed declines in fluvial Arctic grayling and nonnative trout
abundances in the Big Hole River coincide with periods of drought
(Magee and Lamothe 2003, pp. 22-23, 28) and fish kills (Byorth 1995,
pp. 10-11, 31).
Although the response of stream and river habitats to drought is
expected to be most pronounced because of the strong seasonality of
flows in those habitats, effects in lake environments can occur. For
example, both the Upper and Lower Red Rock Lakes are very shallow
(Mogen 1996, p. 7). Increased frequency or duration of drought could
lead to increased warming in shallower lakes, such as Upper Red Rock
Lake. However, the Centennial Valley has many springs sources that
could, at least in part, mitigate for increases in water temperature
due to increased drought frequency and magnitude. Other potential
effects from drought could include a reduction in overall lake depth,
which could in turn affect summer or overwintering habitat. Adfluvial
populations in high mountain lakes would likely not be affected
significantly by drought because air (and thus water) temperatures in
these habitats are relatively cool due to the greater distance from sea
level at high elevations (~ a 3.6 [deg]F (6.5 [deg]C) decrease in air
temperature for every 3,200 ft. (1 kilometer) above sea level; Physics
2014). In addition, most of these habitats are relatively large bodies
of water volumetrically, thus are resistant to warming, given the high
specific heat of water (USGS 2014). Further, intact riparian areas in
these habitats buffer against water temperature increases in
tributaries by blocking incoming solar radiation (Sridhar et al. 2004,
entire; Cassie 2006, p. 1393).
Given the climate of the intermountain West, we conclude that
drought has been and will continue to be a natural occurrence. We
assume that negative effects of drought on Arctic grayling populations,
such as reduced connectivity among habitats or increased water
temperatures at or above physiological thresholds for growth and
survival, are more frequent in stream and river environments and in
very shallow lakes relative to larger, deeper lakes. As discussed under
Factor A, the implementation of the Big Hole Arctic grayling CCAA is
likely to minimize some of the effects of drought in the Big Hole
River, by reducing the likelihood that human-influenced actions or
outcomes (irrigation withdrawals, destruction of riparian habitats, and
fish passage barriers) will interact with the natural effects of
drought (reduced stream flows and increased water temperatures). We
expect the impact of drought may act at the individual level, but not
at the population or DPS level because most grayling populations reside
in drought-resistant habitats in high mountain lakes. Some populations
will likely be affected by drought, but implemented conservation
measures (Big Hole River population) and natural spring sources
(Centennial Valley) are expected to minimize the impact. Overall, we
conclude that drought has been a past threat when many historical
habitats were degraded, but is not a current threat because of the
intact nature of most habitats occupied by Arctic grayling in the upper
Missouri River basin. Drought is expected to increase in both duration
and severity in the future; however, resiliency currently being
incorporated into riparian and aquatic habitats through conservation
projects will likely buffer the effects of drought. Thus, drought is
not expected to pose a threat to the DPS in the future.
Stochastic (Random) Threats, Genetic Diversity and Small Population
Size
A principle of conservation biology is that the presence of larger
and more productive (resilient) populations can reduce overall
extinction risk. To minimize extinction risk due to stochastic (random)
threats, life-history diversity should be maintained, populations
should not all share common catastrophic risks, and both widespread and
spatially close populations are needed (Fausch et al. 2006, p. 23;
Allendorf et al. 1997, entire).
The Upper Missouri River DPS of Arctic grayling exists largely as a
collection of isolated populations (Peterson and Ardren 2009, entire),
with little to no gene flow among populations. While the inability of
fish to move between populations limits genetic exchange and
demographic support (Hilderbrand 2003, p. 257), large population sizes
coupled with adequate number of breeding individuals minimize the
effects of isolation. For example, Grebe Lake, a large population,
receives no genetic infusion from any other population in the upper
Missouri River basin, yet has a very large estimated effective
population size (see Table 3, above). Loss of genetic diversity from
genetic drift is not a concern for this population, despite it being
reproductively isolated.
Abundance among the 20 Arctic grayling populations varies widely
(see Table 3, above). Individually, small populations like Ruby River
need to maintain enough adults to minimize loss of variability through
genetic drift and inbreeding (Rieman and McIntyre 1993, pp. 10-11). The
point estimates of the effective number of breeders observed in all
populations (where data are available) are above the level at which
inbreeding is an immediate concern (Leary 2014, pers. comm.). The Ruby
River population exhibits a low effective number of breeders, but
contains the second highest genetic diversity among all populations
(Leary 2014, unpublished data). Thus, inbreeding depression is probably
not a concern for this population in the near future (Leary 2014, pers.
comm.).
Effective population size estimates for other Arctic grayling
populations vary from 162 to 1,497 (see Table 3, above). There has been
considerable debate about what effective population size is adequate to
conserve genetic diversity and long-term adaptive potential (see
Jamieson and Allendorf 2012 for review, p. 579). However, loss of
genetic diversity is typically not an immediate threat even in isolated
populations with an Ne >100 (Palstra and Ruzzante 2008, p.
3441), but rather is a symptom of deterministic processes acting on the
population (Jamieson and Allendorf
[[Page 49419]]
2012, p. 580). In other words, loss of genetic diversity due to small
effective population size typically does not drive species to
extinction (Jamieson and Allendorf 2012, entire); other processes, such
as habitat degradation, have a more immediate and greater impact on
species persistence (Jamieson and Allendorf 2012). We acknowledge that
loss of genetic diversity can occur in small populations; however, in
this case, it appears that there are adequate numbers of breeding
adults to minimize loss of genetic diversity. Thus, we conclude that
loss of genetic diversity is not a threat at the DPS level.
Conservation of life-history diversity is important to the
persistence of species confronted by habitat change and environmental
perturbations (Beechie et al. 2006, entire). Therefore, the
reintroductions of fluvial Arctic grayling into the upper Ruby River
that have occurred provide redundancy of the fluvial ecotype. The
number of breeding individuals in the Ruby River population has
increased over the last 3 years (Leary 2014, unpublished data). Thus,
there is now a viable replicate of the fluvial ecotype.
Populations of Arctic grayling in the Upper Missouri River DPS are
for the most part widely separated from one another, occupying 7 of 10
historically occupied watersheds (see Table 3, above). Thus, risk of
extirpation by a rare, high-magnitude environmental disturbance (i.e.,
catastrophe) is relatively low. In addition, multiple spawning
locations exist for 11 of the 20 populations in the Upper Missouri
River DPS. The 11 populations with access to multiple spawning
tributaries include all the largest populations in terms of abundance,
except Mussigbrod Lake (see Table 3). Abundance and number of breeding
individuals is adequate in most populations to sustain moderate to high
levels of genetic diversity currently observed. Based on this
information, we conclude that stochastic processes are not a threat to
the Upper Missouri River DPS of Arctic grayling and are not expected to
be in the future.
Summary of Factor E
Overall, we conclude that the Upper Missouri River DPS of Arctic
grayling has faced historical threats from drought, loss of genetic
diversity, and small population size. However, the DPS currently exists
as multiple, isolated populations across a representative portion of
its historical range. While reproductive isolation can lead to
detrimental genetic effects, the current size of most Arctic grayling
populations, trends in effective population size, and number of
breeders suggest these effects will be minimal. Redundancies within and
among populations are present: Multiple spawning tributaries,
geographic separation, life-history replication. Given this
information, we conclude the redundant nature of multiple resilient
populations across a representative portion of the species' historical
range minimizes the impacts of drought, low abundance, reduced genetic
diversity, and lack of a fluvial ecotype replicate. Thus, these are not
current threats, and are not expected to be threats in the future.
Cumulative Effects From Factors A Through E
We limit our discussion of cumulative effects from Factors A
through E to interactions involving climate change. Our rationale for
this is that climate change has the highest level of uncertainty among
other factors considered, and likely has the most potential to affect
Arctic grayling populations when interacting with other factors.
Climate Change and Nonnative Species Interactions
Changes in water temperature due to climate change may influence
the distribution of nonnative trout species (Rahel and Olden 2008, p.
524) and the outcome of competitive interactions between those species
and Arctic grayling. Brown trout are generally considered to be more
tolerant of warm water than many salmonid species common in western
North America (Coutant 1999, pp. 52-53; Selong et al. 2001, p. 1032),
and higher water temperatures may favor brown trout where they compete
against salmonids with lower thermal tolerances (Rahel and Olden 2008,
p. 524). Recently, observed increases in the abundance and distribution
of brown trout in the upper reaches of the Big Hole River (MFWP 2013,
unpublished data) may be consistent with the hypothesis that stream
warming is facilitating encroachment. However, the effect of increased
abundance and distribution of brown trout on Arctic grayling in the Big
Hole River is unknown.
Currently, brown trout are at relatively low densities (<20 fish/
mile) in the upper Big Hole River, where Arctic grayling densities are
highest (MFWP 2013e, unpublished data). At densities of 100 brown trout
per mile (a plausible future scenario), Arctic grayling experts
predicted a 5 percent reduction in Arctic grayling recruitment in the
Big Hole River, due to competition and predation (SSA 2014, p. 2).
Given that natural mortality of salmonid fry is typically high (>90
percent) (Kruse 1959, pp. 329, 333; Bradford 1995, p. 1330), the
predicted reductions in Arctic grayling recruitment by current and
future densities of brown trout in the Big Hole River will likely not
impact Arctic grayling at the population level. Thus, the potential
cumulative effect of climate change and nonnative species interactions
is not a current or future threat for the Upper Missouri River DPS of
Arctic grayling.
Climate Change and Dewatering
Synergistic interactions are possible between effects of climate
change and effects of other potential stressors such as dewatering.
Increases in temperature and changes in precipitation are likely to
affect the availability of water in the West. However, it is difficult
to project how climate change will affect water availability because
increased air and water temperatures may be accompanied and tempered by
more frequent precipitation events. Uncertainty about how different
temperature and precipitation scenarios could affect water availability
make projecting possible synergistic effects of climate change on the
Arctic grayling too speculative at this time.
Summary
Recent genetic analyses have concluded that many of the introduced
populations of Arctic grayling in the upper Missouri River basin
contain moderate to high levels of genetic diversity and that these
populations were created from local sources within the basin. These
introduced populations currently occur within the confines of the upper
Missouri River basin and occupy high quality habitats on Federal land,
the same places the Service would look to for long-term conservation of
the species, if needed. As such, these populations and their future
adaptive potential have conservation value and are included in the
Upper Missouri River DPS of Arctic grayling.
Currently, we recognize 20 populations of Arctic grayling in the
Upper Missouri River DPS, 18 of which occur on Federal land. Adequate
regulatory mechanisms exist to ensure the conservation of habitat on
Federal land for these populations. Historical habitat degradation on
private land has affected the Big Hole River population; however,
habitat conditions have been improving since the implementation of the
Big Hole CCAA in 2006. Conservation actions associated with the Big
Hole CCAA and SHCP have reduced water temperatures in tributaries,
increased instream flows in
[[Page 49420]]
tributaries and the mainstem Big Hole River, connected almost all core
habitat for Arctic grayling, and improved riparian health. Arctic
grayling have responded favorably to these improvements because
abundance and distribution have increased throughout the upper Big Hole
River, and number of breeding adults has increased by a factor of at
least 5 since 2006. The Service is encouraged by the successful track
record of conservation actions implemented under the Big Hole CCAA and
SHCP over the past 7 years.
Riparian restoration efforts in the Big Hole River and Centennial
Valley are ongoing and will continue to be key in mitigating the
anticipated effects of drought and climate change. Increased shading of
tributaries and decreased width-to-depth ratios in stream channels can
effectively minimize effects from increasing air temperatures and
drought. In addition, these changes to habitat can alter predation and
competition potential where both nonnative species and Arctic grayling
coexist, as they have for over 100 years in some populations.
We acknowledge the uncertainty regarding the current status of the
Ennis Reservoir/Madison River population and probable declining trend
in abundance. The factors influencing the current demographics of this
population are unclear. However, we are encouraged by the recent FERC
relicensing agreement precluding reservoir drawdowns that likely
affected this population and its habitat in the past.
In conclusion, we find viable populations of both ecotypes present
in the DPS, the majority of which occur on Federal land and are
protected by Federal land management measures. Numbers of breeding
adults are currently increasing in both strictly fluvial populations
and in the Centennial Valley. High-quality habitat is present for most
populations or is improving where it is not optimal (e.g., Big Hole
River). Health of riparian areas is trending upward and will be key to
minimizing effects of climate change and drought. All Arctic grayling
populations are genetically diverse, are of Montana-origin, and occur
in 7 of 10 historically occupied watersheds.
In 2010, we identified multiple threats as acting on the Upper
Missouri River DPS of Arctic grayling. At that time, we determined that
habitat-related threats included habitat fragmentation, dewatering,
thermal stress, entrainment, riparian habitat loss, and effects from
climate change. Since 2010, we have 4 additional years of monitoring
data and have gained new insight. It is now apparent that these threats
are being effectively mitigated on private land (Big Hole River) by
conservation actions under the Big Hole CCAA and do not appear to be
present or acting at a level to warrant concern on most of the
adfluvial populations. Almost all (98 percent) of Arctic grayling core
habitat in the Big Hole River is now connected. Recent riparian
restoration activities have appreciably reduced water temperatures and
improved riparian habitat in tributaries to the Big Hole River and are
expected to buffer the effects of climate change. Entrainment of Arctic
grayling into irrigation canals in the Big Hole system is low, with no
documented entrainment occurring since 2010. Habitats on Federal land
are largely intact and these populations are not subject to many of the
stressors historically identified for other populations because no
irrigation diversions are present, habitats are primarily high-
elevation lakes that have cool water temperatures, and riparian areas
are largely intact.
In 2010, another threat identified as acting on the Upper Missouri
River DPS of Arctic grayling was the presence of nonnative trout. We
considered nonnative trout a threat at that time because we were aware
of several instances where Arctic grayling declines had occurred
following nonnative trout introductions. Currently, we have a better
understanding of the interactions between nonnative trout and Arctic
grayling. Our review of these interactions and case histories suggests
that habitat degradation, concurrent with nonnative trout
introductions, likely contributed to historical declines in Arctic
grayling in those instances. Further, it appears the effect of
nonnative trout on Arctic grayling are likely habitat-mediated;
nonnative trout affect Arctic grayling disproportionately when habitat
conditions are degraded, but both Arctic grayling and nonnatives can
coexist at viable levels when habitat conditions are improved. The
primary evidence supporting this assertion is the increasing abundance
and distribution of both Arctic grayling and nonnatives in the Big Hole
River (brown trout) and Centennial Valley (Yellowstone cutthroat trout
before suppression began). Another line of evidence to support this
assertion is observed spatial segregation between nonnatives and Arctic
grayling in the core Arctic grayling areas in the Big Hole River,
especially spawning and rearing areas (SSA 2014). In addition, Arctic
grayling in adfluvial habitats have maintained stable or increasing
population levels in the presence of brook, rainbow, and Yellowstone
cutthroat trout for over 100 years in many instances in the upper
Missouri River basin, where habitat degradation has not occurred or
been extensive.
In 2010, we stated that existing regulatory mechanisms were
inadequate to protect the Upper Missouri River DPS of Arctic grayling.
The primary reason for this assertion was that Arctic grayling
populations were reported as declining; thus existing regulatory
mechanisms were believed to be inadequate because they had failed to
halt or reverse this decline. Currently, we have updated information
indicating that 19 of 20 populations of Arctic grayling are either
stable or increasing. Existing regulatory mechanisms have precluded
riparian habitat destruction on Federal lands or mandated restoration
of impaired areas and are expected to provide similar protections in
the future. Given the updated information, we now believe these
regulatory mechanisms are adequate.
In 2010, we identified reduced genetic diversity, low abundance,
random events, drought, and lack of a fluvial replicate as threats to
the Upper Missouri River DPS of Arctic grayling. Updated genetic
information that was not available in 2010 indicates moderate to high
levels of genetic diversity within most Arctic grayling populations in
the DPS. Further, abundance estimates derived from this updated genetic
information indicate higher Arctic grayling abundances than previously
thought. Adequate redundancy exists within the DPS to minimize the
effects of random events and drought; lake habitats occupied by most
Arctic grayling populations are drought-resistant. Lastly, a viable
fluvial replicate now exists (Ruby River), with 5 years of natural
reproduction documented and an increasing number of breeding adults.
Finding
As required by the Act, we considered the five factors in assessing
whether the Upper Missouri River DPS of Arctic grayling is endangered
or threatened throughout all of its range. We examined the best
scientific and commercial information available regarding the present
and future threats faced by the Upper Missouri River DPS of Arctic
grayling. We reviewed the petition, information available in our files
and other available published and unpublished information, including
information submitted by the public, and we consulted with recognized
Arctic grayling experts and other Federal and State agencies. Habitat-
related threats previously identified,
[[Page 49421]]
including habitat fragmentation, dewatering, thermal stress,
entrainment, riparian habitat loss, and effects from climate change,
have been sufficiently ameliorated and the information indicates that
19 of 20 populations of Arctic grayling are either stable or
increasing. On the basis of the best scientific and commercial
information available and the analysis provided above, we find that the
magnitude and imminence of threats do not indicate that the Upper
Missouri River DPS of Arctic grayling 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 Upper Missouri River DPS throughout its range as a
threatened or an endangered species is not warranted at this time.
Significant Portion of the Range
Under the Act and our implementing regulations, a species may
warrant listing if it is an endangered or a threatened species
throughout all or a significant portion of its range. 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 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.'' On July 1, 2014, we published a final policy
interpreting the phrase ``Significant Portion of its Range'' (SPR) (79
FR 37578). The final policy states that (1) if a species is found to be
an endangered or a threatened species throughout a significant portion
of its range, the entire species is listed as an endangered or a
threatened species, respectively, and the Act's protections apply to
all individuals of the species wherever found; (2) a portion of the
range of a species is ``significant'' if the species is not currently
an endangered or a threatened species throughout all of its range, but
the portion's contribution to the viability of the species is so
important that, without the members in that portion, the species would
be in danger of extinction, or likely to become so in the foreseeable
future, throughout all of its range; (3) the range of a species is
considered to be the general geographical area within which that
species can be found at the time FWS or NMFS makes any particular
status determination; and (4) if a vertebrate species is an endangered
or a threatened species throughout an SPR, and the population in that
significant portion is a valid DPS, we will list the DPS rather than
the entire taxonomic species or subspecies.
The SPR policy is applied to all status determinations, including
analyses for the purposes of making listing, delisting, and
reclassification determinations. The procedure for analyzing whether
any portion is an SPR is similar, regardless of the type of status
determination we are making. The first step in our analysis of the
status of a species is to determine its status throughout all of its
range. If we determine that the species is in danger of extinction, or
likely to become so in the foreseeable future, throughout all of its
range, we list the species as an endangered (or threatened) species and
no SPR analysis will be required. If the species is neither an
endangered nor a threatened species throughout all of its range, we
determine whether the species is an endangered or a threatened species
throughout a significant portion of its range. If it is, we list the
species as an endangered or a threatened species, respectively; if it
is not, we conclude that listing the species is not warranted.
When we conduct an SPR analysis, we first identify any portions of
the species' range 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 either
an endangered or a threatened species. 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 in those
portions or likely to become so within the foreseeable future. We
emphasize that answering these questions in the affirmative is not a
determination that the species is an endangered or a threatened species
throughout a significant portion of its range--rather, it is a step in
determining whether a more detailed analysis of the issue is required.
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 affecting it uniformly throughout its range, no portion is likely
to warrant further consideration. Moreover, if any concentration of
threats apply only to portions of the range that clearly do not meet
the biologically based definition of ``significant'' (i.e., the loss of
that portion clearly would not be expected to increase the
vulnerability to extinction of the entire species), those portions will
not warrant further consideration.
If we identify any portions that may be both (1) significant and
(2) endangered or threatened, we engage in a more detailed analysis to
determine whether these standards are indeed met. The identification of
an SPR does not create a presumption, prejudgment, or other
determination as to whether the species in that identified SPR is an
endangered or a threatened species. We must go through a separate
analysis to determine whether the species is an endangered or a
threatened species in the SPR. To determine whether a species is an
endangered or a threatened species throughout an SPR, we will use the
same standards and methodology that we use to determine if a species is
an endangered or a threatened species throughout its range.
Depending on the biology of the species, its range, and the threats
it faces, it may be more efficient to address the ``significant''
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 an endangered or a threatened species
there; if we determine that the species is not an endangered or a
threatened species in a portion of its range, we do not need to
determine if that portion is ``significant.''
We evaluated the current range of the Upper Missouri River DPS of
Arctic grayling to determine if there is any apparent geographic
concentration of potential threats. We examined potential threats from
curtailment of range, dams, habitat fragmentation, dewatering and
thermal stress, entrainment, riparian habitat loss, sediment,
exploitation, disease and competition/predation, drought, climate
change, stochastic events, reduced genetic diversity, low abundance,
and lack of a fluvial ecotype replicate. The type and magnitude of
stressors acting on the Arctic grayling populations in the DPS are
varied.
Currently, nineteen of the twenty Arctic grayling populations in
the DPS are stable or increasing in abundance. Given this trend, we
conclude that there is no concentration of threats acting on these
nineteen populations because these populations are able to maintain
viability, despite some stressors acting at the individual level on
some of these populations. However, we acknowledge the probable
declining population trend in the Ennis Reservoir/Madison River
population. It is unclear what factor or
[[Page 49422]]
combination of factors is contributing to this decline. Nonnative trout
abundance is highest in the Madison River, relative to all other
systems occupied by nonnative trout and Arctic grayling, and this
factor may be contributing to the decline of Arctic grayling in Ennis
Reservoir/Madison River.
Given the probable decline of Arctic grayling in Ennis Reservoir/
Madison River, we analyzed the potential significance of this
population to the overall Upper Missouri River DPS of Arctic grayling.
To do this analysis, we evaluated whether the Ennis Reservoir/Madison
River population's contribution to the viability of the DPS is so
important that, without the members in this portion, the DPS would be
in danger of extinction, or likely to become so in the foreseeable
future, throughout all of its range. The Ennis Reservoir/Madison River
population occupies a small portion of the range within the DPS and
represents only 1 of 20 populations in the overall DPS. We conclude
that the DPS would still be viable if the Ennis Reservoir/Madison River
population were extirpated because adequate redundancy (3 other fluvial
or partially fluvial and 16 other adfluvial populations) of Arctic
grayling populations would still exist. In addition, representation of
resilient populations would remain in the Madison drainage (Grebe Lake
population) and rangewide in 7 of 10 historically occupied watersheds
in the Upper Missouri River basin. Further, resiliency of the DPS would
not be compromised by the loss of the Ennis Reservoir/Madison River
population because all remaining Arctic grayling populations are
widespread and viable. Therefore, in the hypothetical absence of the
Ennis Reservoir/Madison River population, the remainder of the Upper
Missouri River DPS of Arctic grayling would not meet the definition of
threatened or endangered under the Act. For the reasons stated above,
the Ennis Reservoir/Madison River population does not meet the
definition of ``significant'' for the purposes of this SPR analysis.
In conclusion, we find no concentration of stressors acting on
nineteen of twenty Arctic grayling populations in the DPS. The Ennis
Reservoir/Madison River population does appear to have a stressor or
combination of stressors acting at the population level. However,
further analysis indicates that the Ennis Reservoir/Madison River does
not meet the definition of ``significant'' in our SPR policy because
adequate redundancy, representation, and resiliency would still exist
within the DPS if the Ennis Reservoir/Madison River population were
extirpated. Thus, the remainder of the Upper Missouri River DPS of
Arctic grayling would not meet the definition of threatened or
endangered. Therefore, we find that there is not a significant portion
of the range of the Upper Missouri River DPS of Arctic grayling that
warrants listing.
Our review of the best available scientific and commercial
information indicates that the Upper Missouri River DPS of Arctic
grayling is not in danger of extinction (endangered), nor likely to
become endangered within the foreseeable future (threatened),
throughout all or a significant portion of its range. Therefore, we
find that listing the Upper Missouri River DPS of Arctic grayling as an
endangered or threatened species under the Act is not warranted at this
time.
We request that you submit any new information concerning the
status of, or threats to, the Upper Missouri River DPS of Arctic
grayling to our Montana Ecological Services Office (see ADDRESSES)
whenever it becomes available. New information will help us monitor the
Upper Missouri River DPS of Arctic grayling and encourage its
conservation. If an emergency situation develops for the Upper Missouri
River DPS of Arctic grayling, we will act to provide immediate
protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Montana Ecological
Services Office (see ADDRESSES).
Authors
The primary authors of this document are the staff members of the
Montana Ecological Services Office.
Authority
The authority for this section is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 6, 2014.
David Cottingham,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2014-19353 Filed 8-19-14; 4:15 pm]
BILLING CODE 4310-55-P