HomeMy WebLinkAboutAppendix AAPPENDIX A:
STATUS OF THE SPECIES: BULL TROUT
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Appendix: A
Status of the Species: Bull Trout
Taxonomy
The bull trout (Salvelinus confluentus) is a native char found in the coastal and intermountain
west of North America. Dolly Varden (Salvelinus malma) and bull trout were previously
considered a single species and were thought to have coastal and interior forms. However,
Cavender (1978, entire) described morphometric, meristic and osteological characteristics of the
two forms, and provided evidence of specific distinctions between the two. Despite an overlap
in the geographic range of bull trout and Dolly Varden in the Puget Sound area and along the
British Columbia coast, there is little evidence of introgression (Haas and McPhail 1991,
p. 2191). The Columbia River Basin is considered the region of origin for the bull trout. From
the Columbia, dispersal to other drainage systems was accomplished by marine migration and
headwater stream capture. Behnke (2002, p. 297) postulated dispersion to drainages east of the
continental divide may have occurred through the North and South Saskatchewan Rivers
(Hudson Bay drainage) and the Yukon River system. Marine dispersal may have occurred from
Puget Sound north to the Fraser, Skeena and Taku Rivers of British Columbia.
Species Description
Bull trout have unusually large heads and mouths for salmonids. Their body colors can vary
tremendously depending on their environment, but are often brownish green with lighter (often
ranging from pale yellow to crimson) colored spots running along their dorsa and flanks, with
spots being absent on the dorsal fin, and light colored to white under bellies. They have white
leading edges on their fins, as do other species of char. Bull trout have been measured as large
as 103 centimeters (41 inches) in length, with weights as high as 14.5 kilograms (32 pounds)
(Fishbase 2015, p. 1). Bull trout may be migratory, moving throughout large river systems,
lakes, and even the ocean in coastal populations, or they may be resident, remaining in the same
stream their entire lives (Rieman and McIntyre 1993, p. 2; Brenkman and Corbett 2005, p. 1077).
Migratory bull trout are typically larger than resident bull trout (USFWS 1998, p. 31668).
Legal Status
The coterminous United States population of the bull trout was listed as threatened on November
1, 1999 (USFWS 1999, entire). The threatened bull trout generally occurs in the Klamath River
Basin of south-central Oregon; the Jarbidge River in Nevada; the Willamette River Basin in
Oregon; Pacific Coast drainages of Washington, including Puget Sound; major rivers in Idaho,
Oregon, Washington, and Montana, within the Columbia River Basin; and the St. Mary -Belly
River, east of the Continental Divide in northwestern Montana (Bond 1992, p. 4; Brewin and
Brewin 1997, pp. 209-216; Cavender 1978, pp. 165-166; Leary and Allendorf 1997, pp. 715-
720).
Throughout its range, the bull trout are threatened by the combined effects of habitat
degradation, fragmentation, and alterations associated with dewatering, road construction and
maintenance, mining, grazing, the blockage of migratory corridors by dams or other diversion
structures, poor water quality, entrainment (a process by which aquatic organisms are pulled
through a diversion or other device) into diversion channels, and introduced non-native species
(USFWS 1999, p. 58910). Although all salmonids are likely to be affected by climate change,
bull trout are especially vulnerable given that spawning and rearing are constrained by their
location in upper watersheds and the requirement for cold water temperatures (Battin et al. 2007,
entire; Rieman et al. 2007, entire; Porter and Nelitz. 2009, pages 4-8). Poaching and incidental
mortality of bull trout during other targeted fisheries are additional threats.
Life History
The iteroparous reproductive strategy of bull trout has important repercussions for the
management of this species. Bull trout require passage both upstream and downstream, not only
for repeat spawning but also for foraging. Most fish ladders, however, were designed
specifically for anadromous semelparous salmonids (fishes that spawn once and then die, and
require only one-way passage upstream). Therefore, even dams or other barriers with fish
passage facilities may be a factor in isolating bull trout populations if they do not provide a
downstream passage route. Additionally, in some core areas, bull trout that migrate to marine
waters must pass both upstream and downstream through areas with net fisheries at river mouths.
This can increase the likelihood of mortality to bull trout during these spawning and foraging
migrations.
Growth varies depending upon life -history strategy. Resident adults range from 6 to 12 inches
total length, and migratory adults commonly reach 24 inches or more (Goetz 1989, p. 30; Pratt
1985, pp. 28-34). The largest verified bull trout is a 32 -pound specimen caught in Lake Pend
Oreille, Idaho, in 1949 (Simpson and Wallace 1982, p. 95).
Bull trout typically spawn from August through November during periods of increasing flows
and decreasing water temperatures. Preferred spawning habitat consists of low -gradient stream
reaches with loose, clean gravel (Fraley and Shepard 1989, p. 141). Redds are often constructed
in stream reaches fed by springs or near other sources of cold groundwater (Goetz 1989, pp. 15-
16; Pratt 1992, pp. 6-7; Rieman and McIntyre 1996, p. 133). Depending on water temperature,
incubation is normally 100 to 145 days (Pratt 1992, p. 1). After hatching, fry remain in the
substrate, and time from egg deposition to emergence may surpass 200 days. Fry normally
emerge from early April through May, depending on water temperatures and increasing stream
flows (Pratt 1992, p. 1; Ratliff and Howell 1992, p. 10).
Early life stages of fish, specifically the developing embryo, require the highest inter -gravel
dissolved oxygen (IGDO) levels, and are the most sensitive life stage to reduced oxygen levels.
The oxygen demand of embryos depends on temperature and on stage of development, with the
greatest IGDO required just prior to hatching.
A literature review conducted by the Washington Department of Ecology (WDOE 2002, p. 9)
indicates that adverse effects of lower oxygen concentrations on embryo survival are magnified
as temperatures increase above optimal (for incubation). Normal oxygen levels seen in rivers
used by bull trout during spawning ranged from 8 to 12 mg/L (in the gravel), with corresponding
instream levels of 10 to 11.5 mg/L (Stewart et al. 2007, p. 10). In addition, IGDO
concentrations, water velocities in the water column, and especially the intergravel flow rate, are
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interrelated variables that affect the survival of incubating embryos (ODEQ 1995, Ch 2 pp.
23-24). Due to a long incubation period of 220+ days, bull trout are particularly sensitive to
adequate IGDO levels. An IGDO level below 8 mg/L is likely to result in mortality of eggs,
embryos, and fry.
Population Dymanics
Population Structure
Bull trout exhibit both resident and migratory life history strategies. Both resident and migratory
forms may be found together, and either form may produce offspring exhibiting either resident or
migratory behavior (Rieman and McIntyre 1993, p. 2). Resident bull trout complete their entire
life cycle in the tributary (or nearby) streams in which they spawn and rear. The resident form
tends to be smaller than the migratory form at maturity and also produces fewer eggs (Goetz
1989, p. 15). Migratory bull trout spawn in tributary streams where juvenile fish rear 1 to 4
years before migrating to either a lake (adfluvial form), river (fluvial form) (Fraley and Shepard
1989, p. 138; Goetz 1989, p. 24), or saltwater (anadromous form) to rear as subadults and to live
as adults (Brenkman and Corbett 2005, entire; McPhail and Baxter 1996, p. i; WDFW et al.
1997, p. 16). Bull trout normally reach sexual maturity in 4 to 7 years and may live longer than
12 years. They are iteroparous (they spawn more than once in a lifetime). Repeat- and alternate -
year spawning has been reported, although repeat -spawning frequency and post -spawning
mortality are not well documented (Fraley and Shepard 1989, p. 135; Leathe and Graham 1982,
p. 95; Pratt 1992, p. 8; Rieman and McIntyre 1996, p. 133).
Bull trout are naturally migratory, which allows them to capitalize on temporally abundant food
resources and larger downstream habitats. Resident forms may develop where barriers (either
natural or manmade) occur or where foraging, migrating, or overwintering habitats for migratory
fish are minimized (Brenkman and Corbett 2005, pp. 1075-1076; Goetz et al. 2004, p. 105). For
example, multiple life history forms (e.g., resident and fluvial) and multiple migration patterns
have been noted in the Grande Ronde River (Baxter 2002, pp. 96, 98-106). Parts of this river
system have retained habitat conditions that allow free movement between spawning and rearing
areas and the mainstem Snake River. Such multiple life history strategies help to maintain the
stability and persistence of bull trout populations to environmental changes. Benefits to
migratory bull trout include greater growth in the more productive waters of larger streams,
lakes, and marine waters; greater fecundity resulting in increased reproductive potential; and
dispersing the population across space and time so that spawning streams may be recolonized
should local populations suffer a catastrophic loss (Frissell 1999, pp. 861-863; MBTSG 1998, p.
13; Rieman and McIntyre 1993, pp. 2-3). In the absence of the migratory bull trout life form,
isolated populations cannot be replenished when disturbances make local habitats temporarily
unsuitable. Therefore, the range of the species is diminished, and the potential for a greater
reproductive contribution from larger size fish with higher fecundity is lost (Rieman and
McIntyre 1993, p. 2).
Whitesel et al. (2004, p. 2) noted that although there are multiple resources that contribute to the
subject, Spruell et al. (2003, entire) best summarized genetic information on bull trout population
structure. Spruell et al. (2003, entire) analyzed 1,847 bull trout from 65 sampling locations, four
located in three coastal drainages (Klamath, Queets, and Skagit Rivers), one in the Saskatchewan
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River drainage (Belly River), and 60 scattered throughout the Columbia River Basin. They
concluded that there is a consistent pattern among genetic studies of bull trout, regardless of
whether examining allozymes, mitochondrial DNA, or most recently microsatellite loci.
Typically, the genetic pattern shows relatively little genetic variation within populations, but
substantial divergence among populations. Microsatellite loci analysis supports the existence of
at least three major genetically differentiated groups (or evolutionary lineages) of bull trout
(Spruell et al. 2003, p. 17). They were characterized as:
"Coastal", including the Deschutes River and all of the Columbia River drainage
downstream, as well as most coastal streams in Washington, Oregon, and British
Columbia. A compelling case also exists that the Klamath Basin represents a unique
evolutionary lineage within the coastal group.
ii. "Snake River", which also included the John Day, Umatilla, and Walla Walla rivers.
Despite close proximity of the John Day and Deschutes Rivers, a striking level of
divergence between bull trout in these two systems was observed.
iii. "Upper Columbia River" which includes the entire basin in Montana and northern
Idaho. A tentative assignment was made by Spruell et al. (2003, p. 25) of the
Saskatchewan River drainage populations (east of the continental divide), grouping
them with the upper Columbia River group.
Spruell et al. (2003, p. 17) noted that within the major assemblages, populations were further
subdivided, primarily at the level of major river basins. Taylor et al. (1999, entire) surveyed bull
trout populations, primarily from Canada, and found a major divergence between inland and
coastal populations. Costello et al. (2003, p. 328) suggested the patterns reflected the existence
of two glacial refugia, consistent with the conclusions of Spruell et al. (2003, p. 26) and the
biogeographic analysis of Haas and McPhail (2001, entire). Both Taylor et al. (1999, p. 1166)
and Spruell et al. (2003, p. 2 1 ) concluded that the Deschutes River represented the most
upstream limit of the coastal lineage in the Columbia River Basin.
More recently, the U.S. Fish and Wildlife Service (Service) identified additional genetic units
within the coastal and interior lineages (Ardren et al. 2011, p. 18). Based on a recommendation
in the Service's 5 -year review of the species' status (USFWS 2008a, p. 45), the Service
reanalyzed the 27 recovery units identified in the draft bull trout recovery plan (USFWS 2002a,
p. 48) by utilizing, in part, information from previous genetic studies and new information from
additional analysis (Ardren et al. 2011, entire). In this examination, the Service applied relevant
factors from the joint Service and National Marine Fisheries Service Distinct Population
Segment (DPS) policy (USFWS 1996, entire) and subsequently identified six draft recovery
units that contain assemblages of core areas that retain genetic and ecological integrity across the
range of bull trout in the coterminous United States. These six draft recovery units were used to
inform designation of critical habitat for bull trout by providing a context for deciding what
habitats are essential for recovery (USFWS 2010, p. 63898). The six draft recovery units
identified for bull trout in the coterminous United States include: Coastal, Klamath, Mid -
Columbia, Columbia Headwaters, Saint Mary, and Upper Snake. These six draft recovery units
were also identified in the Service's revised recovery plan (USFWS 2015, p. vii) and designated
as final recovery units.
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Population Dynamics
Although bull trout are widely distributed over a large geographic area, they exhibit a patchy
distribution, even in pristine habitats (Rieman and McIntyre 1993, p. 4). Increased habitat
fragmentation reduces the amount of available habitat and increases isolation from other
populations of the same species (Saunders et al. 1991, entire). Burkey (1989, entire) concluded
that when species are isolated by fragmented habitats, low rates of population growth are typical
in local populations and their probability of extinction is directly related to the degree of
isolation and fragmentation. Without sufficient immigration, growth for local populations may
be low and probability of extinction high (Burkey 1989, entire; Burkey 1995, entire).
Metapopulation concepts of conservation biology theory have been suggested relative to the
distribution and characteristics of bull trout, although empirical evidence is relatively scant
(Rieman and McIntyre 1993, p. 15; Dunham and Rieman 1999, entire; Rieman and Dunham
2000, entire). A metapopulation is an interacting network of local populations with varying
frequencies of migration and gene flow among them (Meffe and Carroll 1994, pp. 189-190). For
inland bull trout, metapopulation theory is likely most applicable at the watershed scale where
habitat consists of discrete patches or collections of habitat capable of supporting local
populations; local populations are for the most part independent and represent discrete
reproductive units; and long-term, low -rate dispersal patterns among component populations
influences the persistence of at least some of the local populations (Rieman and Dunham 2000,
entire). Ideally, multiple local populations distributed throughout a watershed provide a
mechanism for spreading risk because the simultaneous loss of all local populations is unlikely.
However, habitat alteration, primarily through the construction of impoundments, dams, and
water diversions has fragmented habitats, eliminated migratory corridors, and in many cases
isolated bull trout in the headwaters of tributaries (Rieman and Clayton 1997, pp. 10-12;
Dunham and Rieman 1999, p. 645; Spruell et al. 1999, pp. 118-120; Rieman and Dunham 2000,
p. 55).
Human -induced factors as well as natural factors affecting bull trout distribution have likely
limited the expression of the metapopulation concept for bull trout to patches of habitat within
the overall distribution of the species (Dunham and Rieman 1999, entire). However, despite the
theoretical fit, the relatively recent and brief time period during which bull trout investigations
have taken place does not provide certainty as to whether a metapopulation dynamic is occurring
(e.g., a balance between local extirpations and recolonizations) across the range of the bull trout
or whether the persistence of bull trout in large or closely interconnected habitat patches
(Dunham and Rieman 1999, entire) is simply reflective of a general deterministic trend towards
extinction of the species where the larger or interconnected patches are relics of historically
wider distribution (Rieman and Dunham 2000, pp. 56-57). Recent research (Whiteley et al.
2003, entire) does, however, provide genetic evidence for the presence of a metapopulation
process for bull trout, at least in the Boise River Basin of Idaho.
Habitat Characteristics
Bull trout have more specific habitat requirements than most other salmonids (Rieman and
McIntyre 1993, p. 4). Habitat components that influence bull trout distribution and abundance
include water temperature, cover, channel form and stability, valley form, spawning and rearing
substrate, and migratory corridors (Fraley and Shepard 1989, entire; Goetz 1989, pp. 23, 25;
Hoelscher and Bjornn 1989, pp. 19, 25; Howell and Buchanan 1992, pp. 30, 32; Pratt 1992,
entire; Rich 1996, p. 17; Rieman and McIntyre 1993, pp. 4-6; Rieman and McIntyre 1995, entire;
Sedell and Everest 1991, entire; Watson and Hillman 1997, entire). Watson and Hillman (1997,
pp. 247-250) concluded that watersheds must have specific physical characteristics to provide
the habitat requirements necessary for bull trout to successfully spawn and rear and that these
specific characteristics are not necessarily present throughout these watersheds. Because bull
trout exhibit a patchy distribution, even in pristine habitats (Rieman and McIntyre 1993, pp. 4-6),
bull trout should not be expected to simultaneously occupy all available habitats.
Migratory corridors link seasonal habitats for all bull trout life histories. The ability to migrate is
important to the persistence of bull trout ( Rieman and McIntyre 1993, p. 2). Migrations
facilitate gene flow among local populations when individuals from different local populations
interbreed or stray to nonnatal streams. Local populations that are extirpated by catastrophic
events may also become reestablished by bull trout migrants. However, it is important to note
that the genetic structuring of bull trout indicates there is limited gene flow among bull trout
populations, which may encourage local adaptation within individual populations, and that
reestablishment of extirpated populations may take a long time (Rieman and McIntyre 1993,
p. 2; Spruell et al. 1999, entire). Migration also allows bull trout to access more abundant or
larger prey, which facilitates growth and reproduction. Additional benefits of migration and its
relationship to foraging are discussed below under "Diet."
Cold water temperatures play an important role in determining bull trout habitat quality, as these
fish are primarily found in colder streams, and spawning habitats are generally characterized by
temperatures that drop below 9 °C in the fall (Fraley and Shepard 1989, p. 137; Pratt 1992, p. 5;
Rieman and McIntyre 1993, p. 2).
Thermal requirements for bull trout appear to differ at different life stages. Spawning areas are
often associated with cold -water springs, groundwater infiltration, and the coldest streams in a
given watershed (Pratt 1992, pp 7-8; Rieman and McIntyre 1993, p. 7). Optimum incubation
temperatures for bull trout eggs range from 2 °C to 6 °C whereas optimum water temperatures
for rearing range from about 6 °C to 10 °C (Buchanan and Gregory 1997, p. 4; Goetz 1989, p.
22). In Granite Creek, Idaho, Bonneau and Scarnecchia (1996, entire) observed that juvenile bull
trout selected the coldest water available in a plunge pool, 8 °C to 9 °C, within a temperature
gradient of 8 °C to 15 °C. In a landscape study relating bull trout distribution to maximum water
temperatures, Dunham et al. (2003, p. 900) found that the probability of juvenile bull trout
occurrence does not become high (i.e., greater than 0.75) until maximum temperatures decline to
11 °C to 12 °C.
Although bull trout are found primarily in cold streams, occasionally these fish are found in
larger, warmer river systems throughout the Columbia River basin (Buchanan and Gregory 1997,
p. 2; Fraley and Shepard 1989, pp. 133, 135; Rieman and McIntyre 1993, pp. 3-4; Rieman and
McIntyre 1995, p. 287). Availability and proximity of cold water patches and food productivity
can influence bull trout ability to survive in warmer rivers (Myrick 2002, pp. 6 and 13).
Z
All life history stages of bull trout are associated with complex forms of cover, including large
woody debris, undercut banks, boulders, and pools (Fraley and Shepard 1989, p. 137; Goetz
1989, p. 19; Hoelscher and Bjornn 1989, p. 38; Pratt 1992, entire; Rich 1996, pp. 4-5; Sedell and
Everest 1991, entire; Sexauer and James 1997, entire; Thomas 1992, pp. 4-6; Watson and
Hillman 1997, p. 238). Maintaining bull trout habitat requires natural stability of stream
channels and maintenance of natural flow patterns (Rieman and McIntyre 1993, pp. 5-6).
Juvenile and adult bull trout frequently inhabit side channels, stream margins, and pools with
suitable cover (Sexauer and James 1997, p. 364). These areas are sensitive to activities that
directly or indirectly affect stream channel stability and alter natural flow patterns. For example,
altered stream flow in the fall may disrupt bull trout during the spawning period, and channel
instability may decrease survival of eggs and young juveniles in the gravel from winter through
spring (Fraley and Shepard 1989, p. 141; Pratt 1992, p. 6; Pratt and Huston 1993, p. 70). Pratt
(1992, p. 6) indicated that increases in fine sediment reduce egg survival and emergence.
Diet
Bull trout are opportunistic feeders, with food habits primarily a function of size and life -history
strategy. Fish growth depends on the quantity and quality of food that is eaten, and as fish grow
their foraging strategy changes as their food changes, in quantity, size, or other characteristics
(Quinn 2005, pp. 195-200). Resident and juvenile migratory bull trout prey on terrestrial and
aquatic insects, macrozooplankton, and small fish (Boag 1987, p. 58; Donald and Alger 1993,
pp. 242-243; Goetz 1989, pp. 33-34). Subadult and adult migratory bull trout feed on various
fish species (Donald and Alger 1993, pp. 241-243; Fraley and Shepard 1989, pp. 135, 138;
Leathe and Graham 1982, pp. 13, 50-56). Bull trout of all sizes other than fry have been found
to eat fish half their length (Beauchamp and VanTassell 2001, p. 204). In nearshore marine areas
of western Washington, bull trout feed on Pacific herring (Clupea pallasi), Pacific sand lance
(Ammodytes hexapterus), and surf smelt (Hypomesus pretiosus) (Goetz et al. 2004, p. 105;
WDFW et al. 1997, p. 23).
Bull trout migration and life history strategies are closely related to their feeding and foraging
strategies. Migration allows bull trout to access optimal foraging areas and exploit a wider
variety of prey resources. For example, in the Skagit River system, anadromous bull trout make
migrations as long as 121 miles between marine foraging areas in Puget Sound and headwater
spawning grounds, foraging on salmon eggs and juvenile salmon along their migration route
(WDFW et al. 1997, p. 25). Anadromous bull trout also use marine waters as migration
corridors to reach seasonal habitats in non -natal watersheds to forage and possibly overwinter
(Brenkman and Corbett 2005, pp. 1078-1079; Goetz et al. 2004, entire).
Status and Distribution
Distribution and Demography
The historical range of bull trout includes major river basins in the Pacific Northwest at about 41
to 60 degrees North latitude, from the southern limits in the McCloud River in northern
California and the Jarbidge River in Nevada to the headwaters of the Yukon River in the
Northwest Territories, Canada (Cavender 1978, pp. 165-166; Bond 1992, p. 2). To the west, the
bull trout's range includes Puget Sound, various coastal rivers of British Columbia, Canada, and
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southeast Alaska (Bond 1992, p. 2). Bull trout occur in portions of the Columbia River and
tributaries within the basin, including its headwaters in Montana and Canada. Bull trout also
occur in the Klamath River basin of south-central Oregon. East of the Continental Divide, bull
trout are found in the headwaters of the Saskatchewan River in Alberta and Montana and in the
MacKenzie River system in Alberta and British Columbia, Canada (Cavender 1978, pp. 165-
166; Brewin et al. 1997, entire).
Each of the following recovery units (below) is necessary to maintain the bull trout's
distribution, as well as its genetic and phenotypic diversity, all of which are important to ensure
the species' resilience to changing environmental conditions. No new local populations have
been identified and no local populations have been lost since listing.
Coastal Recovery Unit
The Coastal Recovery Unit is located within western Oregon and Washington. Major
geographic regions include the Olympic Peninsula, Puget Sound, and Lower Columbia River
basins. The Olympic Peninsula and Puget Sound geographic regions also include their
associated marine waters (Puget Sound, Hood Canal, Strait of Juan de Fuca, and Pacific Coast),
which are critical in supporting the anadromousl life history form, unique to the Coastal
Recovery Unit. The Coastal Recovery Unit is also the only unit that overlaps with the
distribution of Dolly Varden (Salvelinus malma) (Ardren et al. 2011), another native char species
that looks very similar to the bull trout (Haas and McPhail 1991). The two species have likely
had some level of historic introgression in this part of their range (Redenbach and Taylor 2002).
The Lower Columbia River major geographic region includes the lower mainstem Columbia
River, an important migratory waterway essential for providing habitat and population
connectivity within this region. In the Coastal Recovery Unit, there are 21 existing bull trout
core areas which have been designated, including the recently reintroduced Clackamas River
population, and 4 core areas have been identified that could be re-established. Core areas within
the recovery unit are distributed among these three major geographic regions (Puget Sound also
includes one core area that is actually part of the lower Fraser River system in British Columbia,
Canada) (USFWS 2015a, p. A-1).
The current demographic status of bull trout in the Coastal Recovery Unit is variable across the
unit. Populations in the Puget Sound region generally tend to have better demographic status,
followed by the Olympic Peninsula, and finally the Lower Columbia River region. However,
population strongholds do exist across the three regions. The Lower Skagit River and Upper
Skagit River core areas in the Puget Sound region likely contain two of the most abundant bull
trout populations with some of the most intact habitat within this recovery unit. The Lower
Deschutes River core area in the Lower Columbia River region also contains a very abundant
bull trout population and has been used as a donor stock for re-establishing the Clackamas River
population (USFWS 2015a, p. A-6).
` Anadromous: Life history pattern of spawning and rearing in fresh water and migrating to salt water areas to
mature.
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PuLyet Sound Region
In the Puget Sound region, bull trout populations are concentrated along the eastern side
of Puget Sound with most core areas concentrated in central and northern Puget Sound.
Although the Chilliwack River core area is considered part of this region, it is
technically connected to the Fraser River system and is transboundary with British
Columbia making its distribution unique within the region. Most core areas support a
mix of anadromous and fluvial life history forms, with at least two core areas containing
a natural adfluvial life history (Chilliwack River core area [Chilliwack Lake] and
Chester Morse Lake core area). Overall demographic status of core areas generally
improves as you move from south Puget Sound to north Puget Sound. Although
comprehensive trend data are lacking, the current condition of core areas within this
region are likely stable overall, although some at depressed abundances. Two core areas
(Puyallup River and Stillaguamish River) contain local populations at either very low
abundances (Upper Puyallup and Mowich Rivers) or that have likely become locally
extirpated (Upper Deer Creek, South Fork Canyon Creek, and Greenwater River).
Connectivity among and within core areas of this region is generally intact. Most core
areas in this region still have significant amounts of headwater habitat within protected
and relatively pristine areas (e.g., North Cascades National Park, Mount Rainier
National Park, Skagit Valley Provincial Park, Manning Provincial Park, and various
wilderness or recreation areas) (USFWS 2015a, p. A-7).
41Mpic Peninsula Reg on
In the Olympic Peninsula region, distribution of core areas is somewhat disjunct, with
only one located on the west side of Hood Canal on the eastern side of the peninsula,
two along the Strait of Juan de Fuca on the northern side of the peninsula, and three
along the Pacific Coast on the western side of the peninsula. Most core areas support a
mix of anadromous and fluvial life history forms, with at least one core area also
supporting a natural adfluvial life history (Quinault River core area [Quinault Lake]).
Demographic status of core areas is poorest in Hood Canal and Strait of Juan de Fuca,
while core areas along the Pacific Coast of Washington likely have the best
demographic status in this region. The connectivity between core areas in these disjunct
regions is believed to be naturally low due to the geographic distance between them.
Internal connectivity is currently poor within the Skokomish River core area (Hood
Canal) and is being restored in the Elwha River core area (Strait of Juan de Fuca). Most
core areas in this region still have their headwater habitats within relatively protected
areas (Olympic National Park and wilderness areas) (USFWS 2015a, p. A-7).
Lower Columbia River Rion
In the Lower Columbia River region, the majority of core areas are distributed along the
Cascade Crest on the Oregon side of the Columbia River. Only two of the seven core
areas in this region are in Washington. Most core areas in the region historically
supported a fluvial life history form, but many are now adfluvial due to reservoir
G�
construction. However, there is at least one core area supporting a natural adfluvial life
history (Odell Lake) and one supporting a natural, isolated, resident life history (Klickitat
River [West Fork Klickitat]). Status is highly variable across this region, with one
relative stronghold (Lower Deschutes core area) existing on the Oregon side of the
Columbia River. The Lower Columbia River region also contains three watersheds
(North Santiam River, Upper Deschutes River, and White Salmon River) that could
potentially become re-established core areas within the Coastal Recovery Unit. Although
the South Santiam River has been identified as a historic core area, there remains
uncertainty as to whether or not historical observations of bull trout represented a self-
sustaining population. Current habitat conditions in the South Santiam River are thought
to be unable to support bull trout spawning and rearing. Adult abundances within the
majority of core areas in this region are relatively low, generally 300 or fewer
individuals.
Most core populations in this region are not only isolated from one another due to dams
or natural barriers, but they are internally fragmented as a result of manmade barriers.
Local populations are often disconnected from one another or from potential foraging
habitat. In the Coastal Recovery Unit, adult abundance may be lowest in the Hood River
and Odell Lake core areas, which each contain fewer than 100 adults. Bull trout were
reintroduced in the Middle Fork Willamette River in 1990 above Hills Creek Reservoir.
Successful reproduction was first documented in 2006, and has occurred each year since
(USFWS 2015a, p. A-8). Natural reproducing populations of bull trout are present in the
McKenzie River basin (USFWS 2008d, pp. 65-67). Bull trout were more recently
reintroduced into the Clackamas River basin in the summer of 2011 after an extensive
feasibility analysis (Shively et al. 2007, Hudson et al. 2015). Bull trout from the Lower
Deschutes core area are being utilized for this reintroduction effort (USFWS 2015a, p.
A-8).
Klamath Recovery Unit
Bull trout in the Klamath Recovery Unit have been isolated from other bull trout populations for
the past 10,000 years and are recognized as evolutionarily and genetically distinct (Minckley et
al. 1986; Leary et al. 1993; Whitesel et al. 2004; USFWS 2008a; Ardren et al. 2011). As such,
there is no opportunity for bull trout in another recovery unit to naturally re- colonize the
Klamath Recovery Unit if it were to become extirpated. The Klamath Recovery Unit lies at the
southern edge of the species range and occurs in an and portion of the range of bull trout.
Bull trout were once widespread within the Klamath River basin (Gilbert 1897; Dambacher et al.
1992; Ziller 1992; USFWS 2002b), but habitat degradation and fragmentation, past and present
land use practices, agricultural water diversions, and past fisheries management practices have
greatly reduced their distribution. Bull trout abundance also has been severely reduced, and the
remaining populations are highly fragmented and vulnerable to natural or manmade factors that
place them at a high risk of extirpation (USFWS 2002b). The presence of nonnative brook trout
(Salvelinus fontinalis), which compete and hybridize with bull trout, is a particular threat to bull
trout persistence throughout the Klamath Recovery Unit (USFWS 2015b, pp. B-3-4).
10
Upper Klamath Lake Core Area
The Upper Klamath Lake core area comprises two bull trout local populations (Sun
Creek and Threemile Creek). These local populations likely face an increased risk of
extirpation because they are isolated and not interconnected with each other. Extirpation
of other local populations in the Upper Klamath Lake core area has occurred in recent
times (I 970s). Populations in this core area are genetically distinct from those in the
other two core areas in the Klamath Recovery Unit (USFWS 2008b), and in comparison,
genetic variation within this core area is lowest. The two local populations have been
isolated by habitat fragmentation and have experienced population bottlenecks. As such,
currently unoccupied habitat is needed to restore connectivity between the two local
populations and to establish additional populations. This unoccupied habitat includes
canals, which now provide the only means of connectivity as migratory corridors.
Providing full volitional connectivity for bull trout, however, also introduces the risk of
invasion by brook trout, which are abundant in this core area.
Bull trout in the Upper Klamath Lake core area formerly occupied Annie Creek,
Sevenmile Creek, Cherry Creek, and Fort Creek, but are now extirpated from these
locations. The last remaining local populations, Sun Creek and Threemile Creek, have
received focused attention. Brook trout have been removed from bull trout occupied
reaches, and these reaches have been intentionally isolated to prevent brook trout
reinvasion. As such, over the past few generations these populations have become stable
and have increased in distribution and abundance. In 1996, the Threemile Creek
population had approximately 50 fish that occupied a 1.4 -km (0.9 -mile) reach (USFWS
2002b). In 2012, a mark-resight population estimate was completed in Threemile Creek,
which indicated an abundance of 577 (95 percent confidence interval = 475 to 679) age -
1+ fish (ODFW 2012). In addition, the length of the distribution of bull trout in
Threemile Creek had increased to 2.7 km (1.7 miles) by 2012 (USFWS unpublished
data). Between 1989 and 2010, bull trout abundance in Sun Creek increased
approximately tenfold (from approximately 133 to 1,606 age -1+ fish) and distribution
increased from approximately 1.9 km (1.2 miles) to 11.2 km (7.0 miles) (Buktenica et al.
2013) (USFWS 2015b, p. B-5).
Svcan River Core Area
The Sycan River core area is comprised of one local population, Long Creek. Long
Creek likely faces greater risk of extirpation because it is the only remaining local
population due to extirpation of all other historic local populations. Bull trout previously
occupied Calahan Creek, Coyote Creek, and the Sycan River, but are now extirpated
from these locations (Light et al. 1996). This core area's local population is genetically
distinct from those in the other two core areas (USFWS 2008b). This core area also is
essential for recovery because bull trout in this core area exhibit both resident and fluvial
life histories, which are important for representing diverse life history expression in the
Klamath Recovery Unit. Migratory bull trout are able to grow larger than their resident
2 Resident: Life history pattern of residing in tributary streams for the fish's entire life without migrating.
11
counterparts, resulting in greater fecundity and higher reproductive potential (Rieman and
McIntyre 1993). Migratory life history forms also have been shown to be important for
population persistence and resilience (Dunham et al. 2008).
The last remaining population (Long Creek) has received focused attention in an effort to
ensure it is not also extirpated. In 2006, two weirs were removed from Long Creek,
which increased the amount of occupied foraging, migratory, and overwintering (FMO)
habitat by 3.2 km (2.0 miles). Bull trout currently occupy approximately 3.5 km (2.2
miles) of spawning/rearing habitat, including a portion of an unnamed tributary to upper
Long Creek, and seasonally use 25.9 km (16.1 miles) of FMO habitat. Brook trout also
inhabit Long Creek and have been the focus of periodic removal efforts. No recent
statistically rigorous population estimate has been completed for Long Creek; however,
the 2002 Draft Bull Trout Recovery Plan reported a population estimate of 842
individuals (USFWS 2002b). Currently unoccupied habitat is needed to establish
additional local populations, although brook trout are widespread in this core area and
their management will need to be considered in future recovery efforts. In 2014, the
Klamath Falls Fish and Wildlife Office of the Service established an agreement with the
U.S. Geological Survey to undertake a structured decision making process to assist with
recovery planning of bull trout populations in the Sycan River core area (USFWS 2015b,
p. B-6).
Wiper SRrane River Care Area
The Upper Sprague River core area comprises five bull trout local populations, placing
the core area at an intermediate risk of extinction. The five local populations include
Boulder Creek, Dixon Creek, Deming Creek, Leonard Creek, and Brownsworth Creek.
These local populations may face a higher risk of extirpation because not all are
interconnected. Bull trout local populations in this core area are genetically distinct from
those in the other two Klamath Recovery Unit core areas (USFWS 2008b). Migratory
bull trout have occasionally been observed in the North Fork Sprague River (USFWS
2002b). Therefore, this core area also is essential for recovery in that bull trout here
exhibit a resident life history and likely a fluvial life history, which are important for
conserving diverse life history expression in the Klamath Recovery Unit as discussed
above for the Sycan River core area.
The Upper Sprague River core area population of bull trout has experienced a decline
from historic levels, although less is known about historic occupancy in this core area.
Bull trout are reported to have historically occupied the South Fork Sprague River, but
are now extirpated from this location (Buchanan et al. 1997). The remaining five
populations have received focused attention. Although brown trout (Salmo trutta) co-
occur with bull trout and exist in adjacent habitats, brook trout do not overlap with
existing bull trout populations. Efforts have been made to increase connectivity of
existing bull trout populations by replacing culverts that create barriers. Thus, over the
past few generations, these populations have likely been stable and increased in
distribution. Population abundance has been estimated recently for Boulder Creek (372 +
62 percent; Hartill and Jacobs 2007), Dixon Creek (20 + 60 percent; Hartill and Jacobs
2007), Deming Creek (1,316 + 342; Moore 2006), and Leonard Creek (363 + 37 percent;
12
Hartill and Jacobs 2007). No statistically rigorous population estimate has been
completed for the Brownsworth Creek local population; however, the 2002 Draft Bull
Trout Recovery Plan reported a population estimate of 964 individuals (USFWS 2002b).
Additional local populations need to be established in currently unoccupied habitat within
the Upper Sprague River core area, although brook trout are widespread in this core area
and will need to be considered in future recovery efforts (USFWS 2015b, p. B-7).
Mid -Columbia Recovery Unit
The Mid -Columbia Recovery Unit (RU) comprises 24 bull trout core areas, as well as 2
historically occupied core areas and 1 research needs area. The Mid -Columbia RU is recognized
as an area where bull trout have co -evolved with salmon, steelhead, lamprey, and other fish
populations. Reduced fish numbers due to historic overfishing and land management changes
have caused changes in nutrient abundance for resident migratory fish like the bull trout. The
recovery unit is located within eastern Washington, eastern Oregon, and portions of central
Idaho. Major drainages include the Methow River, Wenatchee River, Yakima River, John Day
River, Umatilla River, Walla Walla River, Grande Ronde River, Imnaha River, Clearwater
River, and smaller drainages along the Snake River and Columbia River (USFWS 2015c, p.
C-1).
The Mid -Columbia RU can be divided into four geographic regions the Lower Mid -Columbia,
which includes all core areas that flow into the Columbia River below its confluence with the 1)
Snake River; 2) the Upper Mid -Columbia, which includes all core areas that flow into the
Columbia River above its confluence with the Snake River; 3) the Lower Snake, which includes
all core areas that flow into the Snake River between its confluence with the Columbia River and
Hells Canyon Dam; and 4) the Mid -Snake, which includes all core areas in the Mid -Columbia
RU that flow into the Snake River above Hells Canyon Dam. These geographic regions are
composed of neighboring core areas that share similar bull trout genetic, geographic
(hydrographic), and/or habitat characteristics. Conserving bull trout in geographic regions
allows for the maintenance of broad representation of genetic diversity, provides neighboring
core areas with potential source populations in the event of local extirpations, and provides a
broad array of options among neighboring core areas to contribute recovery under uncertain
environmental change USFWS 2015c, pp. C-1-2).
The current demographic status of bull trout in the Mid -Columbia Recovery Unit is highly
variable at both the RU and geographic region scale. Some core areas, such as the Umatilla,
Asotin, and Powder Rivers, contain populations so depressed they are likely suffering from the
deleterious effects of small population size. Conversely, strongholds do exist within the
recovery unit, predominantly in the Lower Snake geographic area. Populations in the Imnaha,
Little Minam, Clearwater, and Wenaha Rivers are likely some of the most abundant. These
populations are all completely or partially within the bounds of protected wilderness areas and
have some of the most intact habitat in the recovery unit. Status in some core areas is relatively
unknown, but all indications in these core areas suggest population trends are declining,
particularly in the core areas of the John Day Basin (USFWS 2015c, p. C-5).
13
Lower Mid -Columbia Region
In the Lower Mid -Columbia Region, core areas are distributed along the western portion
of the Blue Mountains in Oregon and Washington. Only one of the six core areas is
located completely in Washington. Demographic status is highly variable throughout the
region. Status is the poorest in the Umatilla and Middle Fork John Day Core Areas.
However, the Walla Walla River core area contains nearly pristine habitats in the
headwater spawning areas and supports the most abundant populations in the region.
Most core areas support both a resident and fluvial life history; however, recent evidence
suggests a significant decline in the resident and fluvial life history in the Umatilla River
and John Day core areas respectively. Connectivity between the core areas of the Lower
Mid -Columbia Region is unlikely given conditions in the connecting FMO habitats.
Connection between the Umatilla, Walla Walla and Touchet core areas is uncommon but
has been documented, and connectivity is possible between core areas in the John Day
Basin. Connectivity between the John Day core areas and Umatilla/Walla Walla/Touchet
core areas is unlikely (USFWS 2015c, pp. C-5-6).
Unser Mid -Columbia Region
In the Upper Mid -Columbia Region, core areas are distributed along the eastern side of
the Cascade Mountains in Central Washington. This area contains four core areas
(Yakima, Wenatchee, Entiat, and Methow), the Lake Chelan historic core area, and the
Chelan River, Okanogan River, and Columbia River FMO areas. The core area
populations are generally considered migratory, though they currently express both
migratory (fluvial and adfluvial) and resident forms. Residents are located both above
and below natural barriers (i.e., Early Winters Creek above a natural falls; and Ahtanum
in the Yakima likely due to long lack of connectivity from irrigation withdrawal). In
terms of uniqueness and connectivity, the genetics baseline, radio -telemetry, and PIT tag
studies identified unique local populations in all core areas. Movement patterns within
the core areas; between the lower river, lakes, and other core areas; and between the
Chelan, Okanogan, and Columbia River FMO occurs regularly for some of the
Wenatchee, Entiat, and Methow core area populations. This type of connectivity has
been displayed by one or more fish, typically in non -spawning movements within FMO.
More recently, connectivity has been observed between the Entiat and Yakima core areas
by a juvenile bull trout tagged in the Entiat moving in to the Yakima at Prosser Dam and
returning at an adult size back to the Entiat. Genetics baselines identify unique
populations in all four core areas (USFWS 2015c, p. C-6).
The demographic status is variable in the Upper -Mid Columbia region and ranges from
good to very poor. The Service's 2008 5 -year Review and Conservation Status
Assessment described the Methow and Yakima Rivers at risk, with a rapidly declining
trend. The Entiat River was listed at risk with a stable trend, and the Wenatchee River as
having a potential risk, and with a stable trend. Currently, the Entiat River is considered
to be declining rapidly due to much reduced redd counts. The Wenatchee River is able to
exhibit all freshwater life histories with connectivity to Lake Wenatchee, the Wenatchee
River and all its local populations, and to the Columbia River and/or other core areas in
the region. In the Yakima core area some populations exhibit life history forms different
14
from what they were historically. Migration between local populations and to and from
spawning habitat is generally prevented or impeded by headwater storage dams on
irrigation reservoirs, connectivity between tributaries and reservoirs, and within lower
portions of spawning and rearing habitat and the mainstem Yakima River due to changed
flow patterns, low instream flows, high water temperatures, and other habitat
impediments. Currently, the connectivity in the Yakima Core area is truncated to the
degree that not all populations are able to contribute gene flow to a functional
metapopulation (USFWS 2015c, pp. C-6-7)
Lower Snake Rezion
Demographic status is variable within the Lower Snake Region. Although trend data are
lacking, several core areas in the Grande Ronde Basin and the Imnaha core area are
thought to be stable. The upper Grande Ronde Core Area is the exception where
population abundance is considered depressed. Wenaha, Little Minam, and Imnaha
Rivers are strongholds (as mentioned above), as are most core areas in the Clearwater
River basin. Most core areas contain populations that express both a resident and fluvial
life history strategy. There is potential that some bull trout in the upper Wallowa River
are adfluvial. There is potential for connectivity between core areas in the Grande Ronde
basin, however conditions in FMO are limiting (USFWS 2015c, p. C-7).
Middle Snake Region
In the Middle Snake Region, core areas are distributed along both sides of the Snake
River above Hells Canyon Dam. The Powder River and Pine Creek basins are in Oregon
and Indian Creek and Wildhorse Creek are on the Idaho side of the Snake River.
Demographic status of the core areas is poorest in the Powder River Core Area where
populations are highly fragmented and severely depressed. The East Pine Creek
population in the Pine-Indian-Wildhorse Creeks core area is likely the most abundant
within the region. Populations in both core areas primarily express a resident life history
strategy; however, some evidence suggests a migratory life history still exists in the Pine-
Indian-Wildhorse Creeks core area. Connectivity is severely impaired in the Middle
Snake Region. Dams, diversions and temperature barriers prevent movement among
populations and between core areas. Brownlee Dam isolates bull trout in Wildhorse
Creek from other populations (USFWS 2015c, p. C-7).
Columbia Headwaters Recovery Unit
The Columbia Headwaters Recovery Unit (CHRU) includes western Montana, northern Idaho,
and the northeastern corner of Washington. Major drainages include the Clark Fork River basin
and its Flathead River contribution, the Kootenai River basin, and the Coeur d'Alene Lake basin.
In this implementation plan for the CHRU we have slightly reorganized the structure from the
2002 Draft Recovery Plan, based on latest available science and fish passage improvements that
have rejoined previously fragmented habitats. We now identify 35 bull trout core areas
(compared to 47 in 2002) for this recovery unit. Fifteen of the 35 are referred to as "complex"
core areas as they represent large interconnected habitats, each containing multiple spawning
15
streams considered to host separate and largely genetically identifiable local populations. The 15
complex core areas contain the majority of individual bull trout and the bulk of the designated
critical habitat (USFWS 2010).
However, somewhat unique to this recovery unit is the additional presence of 20 smaller core
areas, each represented by a single local population. These "simple" core areas are found in
remote glaciated headwater basins, often in Glacier National Park or federally -designated
wilderness areas, but occasionally also in headwater valley bottoms. Many simple core areas are
upstream of waterfalls or other natural barriers to fish migration. In these simple core areas bull
trout have apparently persisted for thousands of years despite small populations and isolated
existence. As such, simple core areas meet the criteria for core area designation and continue to
be valued for their uniqueness, despite limitations of size and scope. Collectively, the 20 simple
core areas contain less than 3 percent of the total bull trout core area habitat in the CHRU, but
represent significant genetic and life history diversity (Meeuwig et al. 2010). Throughout this
recovery unit implementation plan, we often separate our analyses to distinguish between
complex and simple core areas, both in respect to threats as well as recovery actions (USFWS
2015d, pp. D-1-2).
In order to effectively manage the recovery unit implementation plan (RUIP) structure in this
large and diverse landscape, the core areas have been separated into the following five natural
geographic assemblages.
Unger Clark Fork Geovraghic ReL►ion
Starting at the Clark Fork River headwaters, the Upper Clark Fork Geographic Region
comprises seven complex core areas, each of which occupies one or more major
watersheds contributing to the Clark Fork basin (i.e., Upper Clark Fork River, Rock
Creek, Blackfoot River, Clearwater River and Lakes, Bitterroot River, West Fork
Bitterroot River, and Middle Clark Fork River core areas) (USFWS 2015d, p. D-2).
Lower Clark Fork Geographic Region
The seven headwater core areas flow into the Lower Clark Fork Geographic Region,
which comprises two complex core areas, Lake Pend Oreille and Priest Lake. Because of
the systematic and jurisdictional complexity (three States and a Tribal entity) and the
current degree of migratory fragmentation caused by five mainstem dams, the threats and
recovery actions in the Lake Pend Oreille (LPO) core area are very complex and are
described in three parts. LPO -A is upstream of Cabinet Gorge Dam, almost entirely in
Montana, and includes the mainstem Clark Fork River upstream to the confluence of the
Flathead River as well as the portions of the lower Flathead River (e.g., Jocko River) on
the Flathead Indian Reservation. LPO -B is the Pend Oreille lake basin proper and its
tributaries, extending between Albeni Falls Dam downstream from the outlet of Lake
Pend Oreille and Cabinet Gorge Dam just upstream of the lake; almost entirely in Idaho.
LPO -C is the lower basin (i.e., lower Pend Oreille River), downstream of Albeni Falls
Dam to Boundary Dam (1 mile upstream from the Canadian border) and bisected by Box
Canyon Dam; including portions of Idaho, eastern Washington, and the Kalispel
Reservation (USFWS 2015d, p. D-2).
16
Historically, and for current purposes of bull trout recovery, migratory connectivity
among these separate fragments into a single entity remains a primary objective.
Flathead Geo,�raphic Region.
The Flathead Geographic Region includes a major portion of northwestern Montana
upstream of Kerr Dam on the outlet of Flathead Lake. The complex core area of Flathead
Lake is the hub of this area, but other complex core areas isolated by dams are Hungry
Horse Reservoir (formerly South Fork Flathead River) and Swan Lake. Within the
glaciated basins of the Flathead River headwaters are 19 simple core areas, many of
which lie in Glacier National Park or the Bob Marshall and Great Bear Wilderness areas
and some of which are isolated by natural barriers or other features (USFWS 2015d,
p. D-2).
Kootenai Geographic Region
To the northwest of the Flathead, in an entirely separate watershed, lies the Kootenai
Geographic Region. The Kootenai is a uniquely patterned river system that originates in
southeastern British Columbia, Canada. It dips, in a horseshoe configuration, into
northwest Montana and north Idaho before turning north again to re-enter British
Columbia and eventually join the Columbia River headwaters in British Columbia. The
Kootenai Geographic Region contains two complex core areas (Lake Koocanusa and the
Kootenai River) bisected since the 1970's by Libby Dam, and also a single naturally
isolated simple core area (Bull Lake). Bull trout in both of the complex core areas retain
strong migratory connections to populations in British Columbia (USFWS 2015d, p.
D-3).
Coeur d'Alene Geo ra hic Region
Finally, the Coeur d'Alene Geographic Region consists of a single, large complex core
area centered on Coeur d'Alene Lake. It is grouped into the CHRU for purposes of
physical and ecological similarity (adfluvial bull trout life history and nonanadromous
linkage) rather than due to watershed connectivity with the rest of the CHRU, as it flows
into the mid -Columbia River far downstream of the Clark Fork and Kootenai systems
(USFWS 2015d, p. D-3).
Upper Snake Recovery Unit
The Upper Snake Recovery Unit includes portions of central Idaho, northern Nevada, and
eastern Oregon. Major drainages include the Salmon River, Malheur River, Jarbidge River,
Little Lost River, Boise River, Payette River, and the Weiser River. The Upper Snake Recovery
Unit contains 22 bull trout core areas within 7 geographic regions or major watersheds: Salmon
River (10 core areas, 123 local populations), Boise River (2 core areas, 29 local populations),
Payette River (5 core areas, 25 local populations), Little Lost River (1 core area, 10 local
populations), Malheur River (2 core areas, 8 local populations), Jarbidge River (I core area, 6
local populations), and Weiser River (I core area, 5 local populations). The Upper Snake
Recovery Unit includes a total of 206 local populations, with almost 60 percent being present in
the Salmon River watershed (USFWS 2015e, p. E-1).
17
Three major bull trout life history expressions are present in the Upper Snake Recovery Unit,
adfluvial3, fluvial4, and resident populations. Large areas of intact habitat exist primarily in the
Salmon drainage, as this is the only drainage in the Upper Snake Recovery Unit that still flows
directly into the Snake River; most other drainages no longer have direct connectivity due to
irrigation uses or instream barriers. Bull trout in the Salmon basin share a genetic past with bull
trout elsewhere in the Upper Snake Recovery Unit. Historically, the Upper Snake Recovery Unit
is believed to have largely supported the fluvial life history form; however, many core areas are
now isolated or have become fragmented watersheds, resulting in replacement of the fluvial life
history with resident or adfluvial forms. The Weiser River, Squaw Creek, Pahsimeroi River, and
North Fork Payette River core areas contain only resident populations of bull trout (USFWS
2015e, pp. E-1-2).
Salmon River
The Salmon River basin represents one of the few basins that are still free-flowing down
to the Snake River. The core areas in the Salmon River basin do not have any major
dams and a large extent (approximately 89 percent) is federally managed, with large
portions of the Middle Fork Salmon River and Middle Fork Salmon River - Chamberlain
core areas occurring within the Frank Church River of No Return Wilderness. Most core
areas in the Salmon River basin contain large populations with many occupied stream
segments. The Salmon River basin contains 10 of the 22 core areas in the Upper Snake
Recovery Unit and contains the majority of the occupied habitat. Over 70 percent of
occupied habitat in the Upper Snake Recovery Unit occurs in the Salmon River basin as
well as 123 of the 206 local populations. Connectivity between core areas in the Salmon
River basin is intact; therefore it is possible for fish in the mainstem Salmon to migrate to
almost any Salmon River core area or even the Snake River.
Connectivity within Salmon River basin core areas is mostly intact except for the
Pahsimeroi River and portions of the Lemhi River. The Upper Salmon River, Lake
Creek, and Opal Lake core areas contain adfluvial populations of bull trout, while most of
the remaining core areas contain fluvial populations; only the Pahsimeroi contains strictly
resident populations. Most core areas appear to have increasing or stable trends but trends
are not known in the Pahsimeroi, Lake Creek, or Opal Lake core areas. The Idaho
Department of Fish and Game reported trend data from 7 of the 10 core areas. This trend
data indicated that populations were stable or increasing in the Upper Salmon River,
Lemhi River, Middle Salmon River -Chamberlain, Little Lost River, and the South Fork
Salmon River (IDFG 2005, 2008). Trends were stable or decreasing in the Little -Lower
Salmon River, Middle Fork Salmon River, and the Middle Salmon River -Panther (IDFG
2005, 2008).
3 Adfluvial: Life history pattern of spawning and rearing in tributary streams and migrating to lakes or reservoirs to
mature.
4 Fluvial: Life history pattern of spawning and rearing in tributary streams and migrating to larger rivers to mature.
Rnicv River
In the Boise River basin, two large dams are impassable barriers to upstream fish
movement: Anderson Ranch Dam on the South Fork Boise River, and Arrowrock Dam
on the mainstem Boise River. Fish in Anderson Ranch Reservoir have access to the
South Fork Boise River upstream of the dam. Fish in Arrowrock Reservoir have access
to the North Fork Boise River, Middle Fork Boise River, and lower South Fork Boise
River. The Boise River basin contains 2 of the 22 core areas in the Upper Snake
Recovery Unit. The core areas in the Boise River basin account for roughly 12 percent of
occupied habitat in the Upper Snake Recovery Unit and contain 29 of the 206 local
populations. Approximately 90 percent of both Arrowrock and Anderson Ranch core
areas are federally owned; most lands are managed by the U.S. Forest Service, with some
portions occurring in designated wilderness areas. Both the Arrowrock core area and the
Anderson Ranch core area are isolated from other core areas. Both core areas contain
fluvial bull trout that exhibit adfluvial characteristics and numerous resident populations.
The Idaho Department of Fish and Game in 2014 determined that the Anderson Ranch
core area had an increasing trend while trends in the Arrowrock core area is unknown
(USFWS 2015e).
Payette River
The Payette River basin contains three major dams that are impassable barriers to fish:
Deadwood Dam on the Deadwood River, Cascade Dam on the North Fork Payette River,
and Black Canyon Reservoir on the Payette River. Only the Upper South Fork Payette
River and the Middle Fork Payette River still have connectivity, the remaining core areas
are isolated from each other due to dams. Both fluvial and adfluvial life history
expression are still present in the Payette River basin but only resident populations are
present in the Squaw Creek and North Fork Payette River core areas. The Payette River
basin contains 5 of the 22 core areas and 25 of the 206 local populations in the recovery
unit. Less than 9 percent of occupied habitat in the recovery unit is in this basin.
Approximately 60 percent of the lands in the core areas are federally owned and the
majority is managed by the U.S. Forest Service. Trend data are lacking and the current
condition of the various core areas is unknown, but there is concern due to the current
isolation of three (North Fork Payette River, Squaw Creek, Deadwood River) of the five
core areas; the presence of only resident local populations in two (North Fork Payette
River, Squaw Creek) of the five core areas; and the relatively low numbers present in the
North Fork core area (USFWS 2015e, p. E-8).
Jarhidke Diver
The Jarbidge River core area contains two major fish barriers along the Bruneau River:
the Buckaroo diversion and C. J. Strike Reservoir. Bull trout are not known to migrate
down to the Snake River. There is one core area in the basin, with populations in the
Jarbidge River; this watershed does not contain any barriers. Approximately 89 percent
of the Jarbidge core area is federally owned. Most lands are managed by either the Forest
Service or Bureau of Land Management. A large portion of the core area is within the
Bruneau-Jarbidge Wilderness area. A tracking study has documented bull trout
19
population connectivity among many of the local populations, in particular between West
Fork Jarbidge River and Pine Creek. Movement between the East and West Fork
Jarbidge River has also been documented; therefore both resident and fluvial populations
are present. The core area contains six local populations and 3 percent of the occupied
habitat in the recovery unit. Trend data are lacking within this core area (USFWS 2015e,
p. E-9).
Little Lost River
The Little Lost River basin is unique in that the watershed is within a naturally occurring
hydrologic sink and has no connectivity with other drainages. A small fluvial population
of bull trout may still exist, but it appears that most populations are predominantly
resident populations. There is one core area in the Little Lost basin, and approximately
89 percent of it is federally owned by either the U.S. Forest Service or Bureau of Land
Management. The core area contains 10 local populations and less than 3 percent of the
occupied habitat in the recovery unit. The current trend condition of this core area is
likely stable, with most bull trout residing in Upper Sawmill Canyon (IDFG 2014).
Malheur River
The Malheur River basin contains major dams that are impassable to fish. The largest are
Warm Springs Dam, impounding Warm Springs Reservoir on the mainstem Malheur
River, and Agency Valley Dam, impounding Beulah Reservoir on the North Fork
Malheur River. The dams result in two core areas that are isolated from each other and
from other core areas. Local populations in the two core areas are limited to habitat in
the upper watersheds. The Malheur River basin contains 2 of the 22 core areas and 8 of
the 206 local populations in the recovery unit. Fluvial and resident populations are
present in both core areas while adfluvial populations are present in the North Fork
Malheur River. This basin contains less than 3 percent of the occupied habitat in the
recovery unit, and approximately 60 percent of lands in the two core areas are federally
owned. Trend data indicates that populations are declining in both core areas (USFWS
2015e, p. E-9).
Weiser River
The Weiser River basin contains local populations that are limited to habitat in the upper
watersheds. The Weiser River basin contains only a single core area that consists of 5 of
the 206 local populations in the recovery unit. Local populations occur in only three
stream complexes in the upper watershed: 1) Upper Hornet Creek, 2) East Fork Weiser
River, and 3) Upper Little Weiser River. These local populations include only resident
life histories. This basin contains less than 2 percent of the occupied habitat in the
recovery unit, and approximately 44 percent of lands are federally owned. Trend data
from the Idaho Department of Fish and Game indicate that the populations in the Weiser
core area are increasing (IDFG 2014) but it is considered vulnerable because local
populations are isolated and likely do not express migratory life histories (USFWS
2015e, p.E-10).
20
St. Mary Recovery Unit
The Saint Mary Recovery Unit is located in northwest Montana east of the Continental Divide
and includes the U.S. portions of the Saint Mary River basin, from its headwaters to the
international boundary with Canada at the 49th parallel. The watershed and the bull trout
population are linked to downstream aquatic resources in southern Alberta, Canada; the U.S.
portion includes headwater spawning and rearing (SR) habitat in the tributaries and a portion of
the FMO habitat in the mainstem of the Saint Mary River and Saint Mary lakes (Mogen and
Kaeding 2001).
The Saint Mary Recovery Unit comprises four core areas; only one (Saint Mary River) is a
complex core area with five described local bull trout populations (Divide, Boulder, Kennedy,
Otatso, and Lee Creeks). Roughly half of the linear extent of available FMO habitat in the
mainstem Saint Mary system (between Saint Mary Falls at the upstream end and the downstream
Canadian border) is comprised of Saint Mary and Lower Saint Mary Lakes, with the remainder
in the Saint Mary River. The other three core areas (Slide Lakes, Cracker Lake, and Red Eagle
Lake) are simple core areas. Slide Lakes and Cracker Lake occur upstream of seasonal or
permanent barriers and are comprised of genetically isolated single local bull trout populations,
wholly within Glacier National Park, Montana. In the case of Red Eagle Lake, physical isolation
does not occur, but consistent with other lakes in the adjacent Columbia Headwaters Recovery
Unit, there is likely some degree of spatial separation from downstream Saint Mary Lake. As
noted, the extent of isolation has been identified as a research need (USFWS 2015f, p. F-1).
Bull trout in the Saint Mary River complex core area are documented to exhibit primarily the
migratory fluvial life history form (Mogen and Kaeding 2005a, 2005b), but there is doubtless
some occupancy (though less well documented) of Saint Mary Lakes, suggesting a partly
adfluvial adaptation. Since lake trout and northern pike are both native to the Saint Mary River
system (headwaters of the South Saskatchewan River drainage draining to Hudson Bay), the
conventional wisdom is that these large piscivores historically outcompeted bull trout in the
lacustrine environment (Donald and Alger 1993, Martinez et al. 2009), resulting in a primarily
fluvial niche and existence for bull trout in this system. This is an untested hypothesis and
additional research into this aspect is needed (USFWS 2015f, p. F-3).
Bull trout populations in the simple core areas of the three headwater lake systems (Slide,
Cracker, and Red Eagle Lakes) are, by definition, adfluvial; there are also resident life history
components in portions of the Saint Mary River system such as Lower Otatso Creek (Mogen and
Kaeding 2005a), further exemplifying the overall life history diversity typical of bull trout.
Mogen and Kaeding (200 1) reported that bull trout continue to inhabit nearly all suitable habitats
accessible to them in the Saint Mary River basin in the United States. The possible exception is
portions of Divide Creek, which appears to be intermittently occupied despite a lack of
permanent migratory barriers, possibly due to low population size and erratic year class
production (USFWS 2015f, p. F-3).
It should be noted that bull trout are found in minor portions of two additional U.S. watersheds
(Belly and Waterton rivers) that were once included in the original draft recovery plan (USFWS
2002) but are no longer considered core areas in the final recovery plan (USFWS 2015) and are
not addressed in that document. In Alberta, Canada, the Saint Mary River bull trout population
21
is considered at "high risk," while the Belly River is rated as "at risk" (ACA 2009). In the Belly
River drainage, which enters the South Saskatchewan system downstream of the Saint Mary
River in Alberta, some bull trout spawning is known to occur on either side of the international
boundary. These waters are in the drainage immediately west of the Saint Mary River
headwaters. However, the U.S. range of this population constitutes only a minor headwater
migratory SR segment of an otherwise wholly Canadian population, extending less than 1 mile
(0.6 km) into backcountry waters of Glacier National Park. The Belly River population is
otherwise totally dependent on management within Canadian jurisdiction, with no natural
migratory connection to the Saint Mary (USFWS 2015f, p. F-3).
Current status of bull trout in the Saint Mary River core area (U.S.) is considered strong (Mogen
2013). Migratory bull trout redd counts are conducted annually in the two major SR streams,
Boulder and Kennedy creeks. Boulder Creek redd counts have ranged from 33 to 66 in the past
decade, with the last 4 counts all 53 or higher. Kennedy Creek redd counts are less robust,
ranging from 5 to 25 over the last decade, with a 2014 count of 20 (USFWS 2015f, p. F-3).
Generally, the demographic status of the Saint Mary River core area is believed to be good, with
the exception of the Divide Creek local population. In this local population, there is evidence
that a combination of ongoing habitat manipulation (Smillie and Ellerbroek 1991,F-5 NPS 1992)
resulting in occasional historical passage issues, combined with low and erratic recruitment
(DeHaan et al. 2011) has caused concern for the continuing existence of the local population.
While less is known about the demographic status of the three simple cores where redd counts
are not conducted, all three appear to be self-sustaining and fluctuating within known historical
population demographic bounds. Of the three simple core areas, demographic status in Slide
Lakes and Cracker Lake appear to be functioning appropriately, but the demographic status in
Red Eagle Lake is less well documented and believed to be less robust (USFWS 2015f, p. F-3).
Reasons for Listing
Bull trout distribution, abundance, and habitat quality have declined rangewide (Bond 1992, pp.
2-3; Schill 1992, p. 42; Thomas 1992, entire; Ziller 1992, entire; Rieman and McIntyre 1993, p.
1; Newton and Pribyl 1994, pp. 4-5; McPhail and Baxter 1996, p. 1). Several local extirpations
have been documented, beginning in the 1950s (Rode 1990, pp. 26-32; Ratliff and Howell 1992,
entire; Donald and Alger 1993, entire; Goetz 1994, p. 1; Newton and Pribyl 1994, pp. 8-9; Light
et al. 1996, pp. 6-7; Buchanan et al. 1997, p. 15; WDFW 1998, pp. 2-3). Bull trout were
extirpated from the southernmost portion of their historic range, the McCloud River in
California, around 1975 (Rode 1990, p. 32). Bull trout have been functionally extirpated (i.e.,
few individuals may occur there but do not constitute a viable population) in the Coeur d'Alene
River basin in Idaho and in the Lake Chelan and Okanogan River basins in Washington (USFWS
1998, pp. 31651-31652).
These declines result from the combined effects of habitat degradation and fragmentation, the
blockage of migratory corridors; poor water quality, angler harvest and poaching, entrainment
(process by which aquatic organisms are pulled through a diversion or other device) into
diversion channels and dams, and introduced nonnative species. Specific land and water
management activities that depress bull trout populations and degrade habitat include the effects
22
of dams and other diversion structures, forest management practices, livestock grazing,
agriculture, agricultural diversions, road construction and maintenance, mining, and urban and
rural development (Beschta et al. 1987, entire; Chamberlain et al. 1991, entire; Furniss et al.
1991, entire; Meehan 1991, entire; Nehlsen et al. 1991, entire; Sedell and Everest 1991, entire;
Craig and Wissmar 1993pp, 18-19; Henjum et al. 1994, pp. 5-6; McIntosh et al. 1994, entire;
Wissmar et al. 1994, entire; MBTSG 1995a, p. 1; MBTSG 1995b. pp. i -ii; MBTSG 1995c, pp. i-
ii; MBTSG 1995d, p. 22; MBTSG 1995e, p. i; MBTSG 1996a, p. i -ii; MBTSG 1996b, p. i;
MBTSG 1996c, p. i; MBTSG 1996d, p. i; MBTSG 1996e, p. i; MBTSG 1996f, p. 11; Light et al.
1996, pp. 6-7; USDA and USDI 1995, p. 2).
Emerging Threats
Climate Chance
Climate change was not addressed as a known threat when bull trout was listed. The
2015 bull trout recovery plan and RUIPs summarize the threat of climate change and
acknowledges that some extant bull trout core area habitats will likely change (and may
be lost) over time due to anthropogenic climate change effects, and use of best available
information will ensure future conservation efforts that offer the greatest long-term
benefit to sustain bull trout and their required coldwater habitats (USFWS 2015, p. vii,
and pp. 17-20, USFWS 2015a -f).
Global climate change and the related warming of global climate have been well
documented (IPCC 2007, entire; ISAB 2007, entire; Combes 2003, entire). Evidence of
global climate change/warming includes widespread increases in average air and ocean
temperatures and accelerated melting of glaciers, and rising sea level. Given the
increasing certainty that climate change is occurring and is accelerating (IPCC 2007,
p. 253; Battin et al. 2007, p. 6720), we can no longer assume that climate conditions in
the future will resemble those in the past.
Patterns consistent with changes in climate have already been observed in the range of
many species and in a wide range of environmental trends (ISAB 2007, entire; Hari et al.
2006, entire; Rieman et al. 2007, entire). In the northern hemisphere, the duration of ice
cover over lakes and rivers has decreased by almost 20 days since the mid -1800's
(Magnuson et al. 2000, p. 1743). The range of many species has shifted poleward and
elevationally upward. For cold -water associated salmonids in mountainous regions,
where their upper distribution is often limited by impassable barriers, an upward thermal
shift in suitable habitat can result in a reduction in range, which in turn can lead to a
population decline (Hari et al. 2006, entire).
In the Pacific Northwest, most models project warmer air temperatures and increases in
winter precipitation and decreases in summer precipitation. Warmer temperatures will
lead to more precipitation falling as rain rather than snow. As the seasonal amount of
snow pack diminishes, the timing and volume of stream flow are likely to change and
peak river flows are likely to increase in affected areas. Higher air temperatures are also
23
likely to increase water temperatures (ISAB 2007, pp. 15-17). For example, stream
gauge data from western Washington over the past 5 to 25 years indicate a marked
increasing trend in water temperatures in most major rivers.
Climate change has the potential to profoundly alter the aquatic ecosystems upon which
the bull trout depends via alterations in water yield, peak flows, and stream temperature,
and an increase in the frequency and magnitude of catastrophic wildfires in adjacent
terrestrial habitats (Bisson et al. 2003, pp 216-217).
All life stages of the bull trout rely on cold water. Increasing air temperatures are likely
to impact the availability of suitable cold water habitat. For example, ground water
temperature is generally correlated with mean annual air temperature, and has been
shown to strongly influence the distribution of other chars. Ground water temperature is
linked to bull trout selection of spawning sites, and has been shown to influence the
survival of embryos and early juvenile rearing of bull trout (Baxter 1997, p. 82).
Increases in air temperature are likely to be reflected in increases in both surface and
groundwater temperatures.
Climate change is likely to affect the frequency and magnitude of fires, especially in
warmer drier areas such as are found on the eastside of the Cascade Mountains. Bisson et
al. (2003, pp. 216-217) note that the forest that naturally occurred in a particular area may
or may not be the forest that will be responding to the fire regimes of an altered climate.
In several studies related to the effect of large fires on bull trout populations, bull trout
appear to have adapted to past fire disturbances through mechanisms such as dispersal
and plasticity. However, as stated earlier, the future may well be different than the past
and extreme fire events may have a dramatic effect on bull trout and other aquatic
species, especially in the context of continued habitat loss, simplification and
fragmentation of aquatic systems, and the introduction and expansion of exotic species
(Bisson et al. 2003, pp. 218-219).
Migratory bull trout can be found in lakes, large rivers and marine waters. Effects of
climate change on lakes are likely to impact migratory adfluvial bull trout that seasonally
rely upon lakes for their greater availability of prey and access to tributaries. Climate -
warming impacts to lakes will likely lead to longer periods of thermal stratification and
coldwater fish such as adfluvial bull trout will be restricted to these bottom layers for
greater periods of time. Deeper thermoclines resulting from climate change may further
reduce the area of suitable temperatures in the bottom layers and intensify competition
for food (Shuter and Meisner 1992. p. 11).
Bull trout require very cold water for spawning and incubation. Suitable spawning
habitat is often found in accessible higher elevation tributaries and headwaters of rivers.
However, impacts on hydrology associated with climate change are related to shifts in
timing, magnitude and distribution of peak flows that are also likely to be most
pronounced in these high elevation stream basins (Battin et al. 2007, p. 6720). The
increased magnitude of winter peak flows in high elevation areas is likely to impact the
location, timing, and success of spawning and incubation for the bull trout and Pacific
24
salmon species. Although lower elevation river reaches are not expected to experience as
severe an impact from alterations in stream hydrology, they are unlikely to provide
suitably cold temperatures for bull trout spawning, incubation and juvenile rearing.
As climate change progresses and stream temperatures warm, thermal refugia will be
critical to the persistence of many bull trout populations. Thermal refugia are important
for providing bull trout with patches of suitable habitat during migration through or to
make feeding forays into areas with greater than optimal temperatures.
There is still a great deal of uncertainty associated with predictions relative to the timing,
location, and magnitude of future climate change. It is also likely that the intensity of
effects will vary by region (ISAB 2007, p 7) although the scale of that variation may
exceed that of States. For example, several studies indicate that climate change has the
potential to impact ecosystems in nearly all streams throughout the State of Washington
(ISAB 2007, p. 13; Battin et al. 2007, p. 6722; Rieman et al. 2007, pp. 1558-1561). In
streams and rivers with temperatures approaching or at the upper limit of allowable water
temperatures, there is little if any likelihood that bull trout will be able to adapt to or
avoid the effects of climate change/warming. There is little doubt that climate change is
and will be an important factor affecting bull trout distribution. As its distribution
contracts, patch size decreases and connectivity is truncated, bull trout populations that
may be currently connected may face increasing isolation, which could accelerate the rate
of local extinction beyond that resulting from changes in stream temperature alone
(Rieman et al. 2007, pp. 1559-1560). Due to variations in land form and geographic
location across the range of the bull trout, it appears that some populations face higher
risks than others. Bull trout in areas with currently degraded water temperatures and/or at
the southern edge of its range may already be at risk of adverse impacts from current as
well as future climate change.
The ability to assign the effects of gradual global climate change to bull trout or to a
specific location on the ground is beyond our technical capabilities at this time.
Conservation
Conservation Needs
The 2015 recovery plan for bull trout established the primary strategy for recovery of bull
trout in the coterminous United States: 1) conserve bull trout so that they are
geographically widespread across representative habitats and demographically stable in
six recovery units; 2) effectively manage and ameliorate the primary threats in each of six
recovery units at the core area scale such that bull trout are not likely to become
endangered in the foreseeable future; 3) build upon the numerous and ongoing
conservation actions implemented on behalf of bull trout since their listing in 1999, and
improve our understanding of how various threat factors potentially affect the species; 4)
use that information to work cooperatively with our partners to design, fund, prioritize,
25
and implement effective conservation actions in those areas that offer the greatest long-
term benefit to sustain bull trout and where recovery can be achieved; and 5) apply
adaptive management principles to implementing the bull trout recovery program to
account for new information (USFWS 2015, p. v.).
Information presented in prior draft recovery plans published in 2002 and 2004 (USFWS
2002a, 2004) have served to identify recovery actions across the range of the species and
to provide a framework for implementing numerous recovery actions by our partner
agencies, local working groups, and others with an interest in bull trout conservation.
The 2015 recovery plan (USFWS 2015) integrates new information collected since the
1999 listing regarding bull trout life history, distribution, demographics, conservation
successes, etc., and integrates and updates previous bull trout recovery planning efforts
across the range of the single DPS listed under the Endangered Species Act of 1973, as
amended (16 U.S.C. 1531 et seq.) (Act).
The Service has developed a recovery approach that: 1) focuses on the identification of
and effective management of known and remaining threat factors to bull trout in each
core area; 2) acknowledges that some extant bull trout core area habitats will likely
change (and may be lost) over time; and 3) identifies and focuses recovery actions in
those areas where success is likely to meet our goal of ensuring the certainty of
conservation of genetic diversity, life history features, and broad geographical
representation of remaining bull trout populations so that the protections of the Act are no
longer necessary (USFWS 2015, p. 45-46).
To implement the recovery strategy, the 2015 recovery plan establishes categories of
recovery actions for each of the six Recovery Units (USFWS 2015, p. 50-51):
1. Protect, restore, and maintain suitable habitat conditions for bull trout.
2. Minimize demographic threats to bull trout by restoring connectivity or
populations where appropriate to promote diverse life history strategies and
conserve genetic diversity.
3. Prevent and reduce negative effects of nonnative fishes and other nonnative taxa
on bull trout.
4. Work with partners to conduct research and monitoring to implement and
evaluate bull trout recovery activities, consistent with an adaptive management
approach using feedback from implemented, site-specific recovery tasks, and
considering the effects of climate change.
Bull trout recovery is based on a geographical hierarchical approach. Bull trout are listed
as a single DPS within the five -state area of the coterminous United States. The single
DPS is subdivided into six biologically -based recover units: 1) Coastal Recovery Unit;
2) Klamath Recovery Unit; 3) Mid -Columbia Recovery Unit; 4) Upper Snake Recovery
Unit; 5) Columbia Headwaters Recovery Unit; and 6) Saint Mary Recovery Unit
(USFWS 2015, p. 23). A viable recovery unit should demonstrate that the three primary
principles of biodiversity have been met: representation (conserving the genetic makeup
26
of the species); resiliency (ensuring that each population is sufficiently large to withstand
stochastic events); and redundancy (ensuring a sufficient number of populations to
withstand catastrophic events) (USFWS 2015, p. 33).
Each of the six recovery units contain multiple bull trout core areas, 116 total, which are
non -overlapping watershed -based polygons, and each core area includes one or more
local populations. Currently there are 109 occupied core areas, which comprise 611 local
populations (USFWS 2015, p. 3). There are also six core areas where bull trout
historically occurred but are now extirpated, and one research needs area where bull trout
were known to occur historically, but their current presence and use of the area are
uncertain (USFWS 2015, p. 3). Core areas can be further described as complex or simple
(USFWS 2015, p. 3-4). Complex core areas contain multiple local bull trout populations,
are found in large watersheds, have multiple life history forms, and have migratory
connectivity between spawning and rearing habitat and FMO habitats. Simple core areas
are those that contain one bull trout local population. Simple core areas are small in
scope, isolated from other core areas by natural barriers, and may contain unique genetic
or life history adaptations.
A local population is a group of bull trout that spawn within a particular stream or portion
of a stream system (USFWS 2015, p. 73). A local population is considered to be the
smallest group of fish that is known to represent an interacting reproductive unit. For
most waters where specific information is lacking, a local population may be represented
by a single headwater tributary or complex of headwater tributaries. Gene flow may
occur between local populations (e.g., those within a core population), but is assumed to
be infrequent compared with that among individuals within a local population.
Recovery Units and Local Populations
The final recovery plan (USFWS 2015) designates six bull trout recovery units as described
above. These units replace the 5 interim recovery units previously identified (USFWS 1999).
The Service will address the conservation of these final recovery units in our section 7(a)(2)
analysis for proposed Federal actions. The recovery plan (USFWS 2015), identified threats and
factors affecting the bull trout within these units. A detailed description of recovery
implementation for each recovery unit is provided in separate recovery unit implementation
plans (RUIPs)(USFWS 2015a -f), which identify conservation actions and recommendations
needed for each core area, forage/ migration/ overwinter areas, historical core areas, and research
needs areas. Each of the following recovery units (below) is necessary to maintain the bull
trout's distribution, as well as its genetic and phenotypic diversity, all of which are important to
ensure the species' resilience to changing environmental conditions.
Coastal Recovery Unit
The coastal recovery unit implementation plan describes the threats to bull trout and the site-
specific management actions necessary for recovery of the species within the unit (USFWS
2015a). The Coastal Recovery Unit is located within western Oregon and Washington. The
Coastal Recovery Unit is divided into three regions: Puget Sound, Olympic Peninsula, and the
Lower Columbia River Regions. This recovery unit contains 20 core areas comprising 84 local
27
populations and a single potential local population in the historic Clackamas River core area
where bull trout had been extirpated and were reintroduced in 2011, and identified four
historically occupied core areas that could be re-established (USFWS 2015, pg. 47; USFWS
2015a, p. A-2). Core areas within Puget Sound and the Olympic Peninsula currently support the
only anadromous local populations of bull trout. This recovery unit also contains ten shared
FMO habitats which are outside core areas and allows for the continued natural population
dynamics in which the core areas have evolved (USFWS 2015a, p. A-5). There are four core
areas within the Coastal Recovery Unit that have been identified as current population
strongholds: Lower Skagit, Upper Skagit, Quinault River, and Lower Deschutes River (USFWS
2015, p.79). These are the most stable and abundant bull trout populations in the recovery unit.
The current condition of the bull trout in this recovery unit is attributed to the adverse effects of
climate change, loss of functioning estuarine and nearshore marine habitats, development and
related impacts (e.g., flood control, floodplain disconnection, bank armoring, channel
straightening, loss of instream habitat complexity), agriculture (e.g., diking, water control
structures, draining of wetlands, channelization, and the removal of riparian vegetation, livestock
grazing), fish passage (e.g., dams, culverts, instream flows) residential development,
urbanization, forest management practices (e.g., timber harvest and associated road building
activities), connectivity impairment, mining, and the introduction of non-native species.
Conservation measures or recovery actions implemented include relicensing of major
hydropower facilities that have provided upstream and downstream fish passage or complete
removal of dams, land acquisition to conserve bull trout habitat, floodplain restoration, culvert
removal, riparian revegetation, levee setbacks, road removal, and projects to protect and restore
important nearshore marine habitats.
Klamath Recovery Unit
The Klamath recovery unit implementation plan describes the threats to bull trout and the site-
specific management actions necessary for recovery of the species within the unit (USFWS
2015b). The Klamath Recovery Unit is located in southern Oregon and northwestern California.
The Klamath Recovery Unit is the most significantly imperiled recovery unit, having
experienced considerable extirpation and geographic contraction of local populations and
declining demographic condition, and natural re -colonization is constrained by dispersal barriers
and presence of nonnative brook trout (USFWS 2015, p. 39). This recovery unit currently
contains three core areas and eight local populations (USFWS 2015, p. 47; USFWS 2015b, p.
B-1). Nine historic local populations of bull trout have become extirpated (USFWS 2015b, p.
B-1). All three core areas have been isolated from other bull trout populations for the past
10,000 years (USFWS 2015b, p. B-3. The current condition of the bull trout in this recovery unit
is attributed to the adverse effects of climate change, habitat degradation and fragmentation, past
and present land use practices, agricultural water diversions, nonnative species, and past fisheries
management practices. Conservation measures or recovery actions implemented include
removal of nonnative fish (e.g., brook trout, brown trout, and hybrids), acquiring water rights for
instream flows, replacing diversion structures, installing fish screens, constructing bypass
channels, installing riparian fencing, culver replacement, and habitat restoration.
Mid -Columbia Recovery Unit
The Mid -Columbia recovery unit implementation plan describes the threats to bull trout and the
site-specific management actions necessary for recovery of the species within the unit (USFWS
2015c). The Mid -Columbia Recovery Unit is located within eastern Washington, eastern Oregon,
and portions of central Idaho. The Mid -Columbia Recovery Unit is divided into four geographic
regions: Lower Mid -Columbia, Upper Mid -Columbia, Lower Snake, and Mid -Snake Geographic
Regions. This recovery unit contains 24 occupied core areas comprising 142 local populations,
two historically occupied core areas, one research needs area, and seven FMO habitats (USFWS
2015, pg. 47; USFWS 2015c, p. C-1-4). The current condition of the bull trout in this recovery
unit is attributed to the adverse effects of climate change, agricultural practices (e.g. irrigation,
water withdrawals, livestock grazing), fish passage (e.g. dams, culverts), nonnative species,
forest management practices, and mining. Conservation measures or recovery actions
implemented include road removal, channel restoration, mine reclamation, improved grazing
management, removal of fish barriers, and instream flow requirements.
Columbia Headwaters Recovery Unit
The Columbia headwaters recovery unit implementation plan describes the threats to bull trout
and the site-specific management actions necessary for recovery of the species within the unit
(USFWS 2015d, entire). The Columbia Headwaters Recovery Unit is located in western
Montana, northern Idaho, and the northeastern corner of Washington. The Columbia
Headwaters Recovery Unit is divided into five geographic regions: Upper Clark Fork, Lower
Clark Fork, Flathead, Kootenai, and Coeur d'Alene Geographic Regions (USFWS 2015d, pp.
D-2 — D-4). This recovery unit contains 35 bull trout core areas; 15 of which are complex core
areas as they represent larger interconnected habitats and 20 simple core areas as they are
isolated headwater lakes with single local populations. The 20 simple core areas are each
represented by a single local population, many of which may have persisted for thousands of
years despite small populations and isolated existence (USFWS 2015d, p. D-1). Fish passage
improvements within the recovery unit have reconnected some previously fragmented habitats
(USFWS 2015d, p. D-1), while others remain fragmented. Unlike the other recovery units in
Washington, Idaho and Oregon, the Columbia Headwaters Recovery Unit does not have any
anadromous fish overlap. Therefore, bull trout within the Columbia Headwaters Recovery Unit
do not benefit from the recovery actions for salmon (USFWS 2015d, p. D-41). The current
condition of the bull trout in this recovery unit is attributed to the adverse effects of climate
change, mostly historical mining and contamination by heavy metals, expanding populations of
nonnative fish predators and competitors, modified instream flows, migratory barriers (e.g.,
dams), habitat fragmentation, forest practices (e.g., logging, roads), agriculture practices (e.g.
irrigation, livestock grazing), and residential development. Conservation measures or recovery
actions implemented include habitat improvement, fish passage, and removal of nonnative
species.
Upper Snake Recovery Unit
The Upper Snake recovery unit implementation plan describes the threats to bull trout and the
site-specific management actions necessary for recovery of the species within the unit (USFWS
2015e, entire). The Upper Snake Recovery Unit is located in central Idaho, northern Nevada,
wt
and eastern Oregon. The Upper Snake Recovery Unit is divided into seven geographic regions:
Salmon River, Boise River, Payette River, Little Lost River, Malheur River, Jarbidge River, and
Weiser River. This recovery unit contains 22 core areas and 207 local populations (USFWS
2015, p. 47), with almost 60 percent being present in the Salmon River Region. The current
condition of the bull trout in this recovery unit is attributed to the adverse effects of climate
change, dams, mining, forest management practices, nonnative species, and agriculture (e.g.,
water diversions, grazing). Conservation measures or recovery actions implemented include
instream habitat restoration, instream flow requirements, screening of irrigation diversions, and
riparian restoration.
St. Mary Recovery Unit
The St. Mary recovery unit implementation plan describes the threats to bull trout and the site-
specific management actions necessary for recovery of the species within the unit (USFWS
2015f). The Saint Mary Recovery Unit is located in Montana but is heavily linked to
downstream resources in southern Alberta, Canada. Most of the Saskatchewan River watershed
which the St. Mary flows into is located in Canada. The United States portion includes
headwater spawning and rearing habitat and the upper reaches of FMO habitat. This recovery
unit contains four core areas, and seven local populations (USFWS 2015f, p. F-1) in the U.S.
Headwaters. The current condition of the bull trout in this recovery unit is attributed primarily to
the outdated design and operations of the Saint Mary Diversion operated by the Bureau of
Reclamation (e.g., entrainment, fish passage, instream flows), and, to a lesser extent habitat
impacts from development and nonnative species.
Tribal Conservation Activities
Many Tribes throughout the range of the bull trout are participating on bull trout conservation
working groups or recovery teams in their geographic areas of interest. Some tribes are also
implementing projects which focus on bull trout or that address anadromous fish but benefit bull
trout (e.g., habitat surveys, passage at dams and diversions, habitat improvement, and movement
studies).
92
LITERATURE CITED
[ACA] Alberta Sustainable Resource Development and Alberta Conservation Association. 2009.
Status of the bull trout (Salvelinus confluentus) in Alberta: Update 2009. Alberta
Sustainable Resource Development. Wildlife Status Report No. 39 (Update 2009).
Edmonton, Alberta.
Ardren, W. R., P. W. DeHaan, C. T. Smith, E. B. Taylor, R. Leary, C. C. Kozfkay, L. Godfrey,
M. Diggs, W. Fredenberg, and J. Chan. 2011. Genetic structure, evolutionary history,
and conservation units of bull trout in the coterminous United States. Transactions of the
American Fisheries Society 140:506-525. 22 pp.
Battin, J., M.W. Wiley, M.H. Ruckelshaus, R.N. Palmer, E. Korb, K.K. Bartz, and H. Imaki.
2007. Projected impacts of climate change on salmon habitat restoration. Proceedings of
the National Academy of Sciences of the United States of America 104(16):6720-6725. 6
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