[Federal Register Volume 80, Number 33 (Thursday, February 19, 2015)]
[Rules and Regulations]
[Pages 9125-9150]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-02951]
[[Page 9125]]
Vol. 80
Thursday,
No. 33
February 19, 2015
Part IV
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
-----------------------------------------------------------------------
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Removing the Oregon Chub
From the Federal List of Endangered and Threatened Wildlife; Final Rule
Federal Register / Vol. 80 , No. 33 / Thursday, February 19, 2015 /
Rules and Regulations
[[Page 9126]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R1-ES-2014-0002; FXES11130900000C6-156-FF09E42000]
RIN 1018-BA28
Endangered and Threatened Wildlife and Plants; Removing the
Oregon Chub From the Federal List of Endangered and Threatened Wildlife
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are removing
the Oregon chub (Oregonichthys crameri) from the Federal List of
Endangered and Threatened Wildlife. This determination is based on a
thorough review of the best available scientific and commercial
information, which indicates that the Oregon chub has recovered and no
longer meets the definition of an endangered species or a threatened
species under the Endangered Species Act of 1973, as amended (Act). Our
review of the status of this species shows that the threats to this
species have been eliminated or reduced and populations are stable so
that the species is not currently, and is not likely to again become, a
threatened species within the foreseeable future in all or a
significant portion of its range. This rule also removes the currently
designated critical habitat for the Oregon chub throughout its range.
DATES: This rule is effective on March 23, 2015.
ADDRESSES: This final rule and the post-delisting monitoring plan are
available on the Internet at http://www.regulations.gov at Docket
Number FWS-R1-ES-2014-0002. Comments and materials received, as well as
supporting documentation used in the preparation of this rule, will be
available for public inspection, by appointment, during normal business
hours, at the Service's Oregon Fish and Wildlife Office, 2600 SE 98th
Avenue, Portland, OR 97266.
FOR FURTHER INFORMATION CONTACT: Paul Henson, State Supervisor, Oregon
Fish and Wildlife Office (see ADDRESSES); telephone 503-231-6179; or
facsimile (fax) 503-231-6195. Persons who use a telecommunications
device for the deaf (TDD) may call the Federal Information Relay
Services (FIRS) at 800-877-8339 for assistance.
SUPPLEMENTARY INFORMATION:
Executive Summary
This document contains: (1) A final rule to remove the Oregon chub
from the Federal List of Endangered and Threatened Wildlife, and (2) a
notice of availability of a final post-delisting monitoring plan.
Species addressed--The Oregon chub (Oregonichthys crameri) is
endemic to the Willamette River drainage of western Oregon. Extensive
human activities in the Willamette River Basin (e.g., dams, levees, and
other human development within the floodplain) have substantially
reduced the amount and suitability of habitat for this species.
Improved floodplain management and floodplain restoration by multiple
conservation partners has reduced and mitigated adverse human-related
impacts and resulted in significant improvements to habitat quality and
quantity. As a result, threats to the Oregon chub have been largely
ameliorated.
The status of the species has improved dramatically due to the
discovery of many new populations and successful reintroductions within
the species' historical range. At the time of listing in 1993 (58 FR
53800, October 18, 1993), only nine known populations of Oregon chub
existed, and few estimates existed of the number of individuals within
each population. The locations of these populations represented a small
fraction (estimated as 2 percent based on stream miles) of the species'
formerly extensive distribution within the Willamette River drainage.
In 2013, 77 populations were known to exist throughout the Willamette
River drainage. The risk of extinction is substantially reduced as
threats have been ameliorated and new populations have been discovered
or established.
Purpose of the Regulatory Action--Under the Endangered Species Act
of 1973, we may be petitioned to list, delist, or reclassify a species.
In 2010, we reclassified the Oregon chub from endangered to threatened
(75 FR 21179, April 23, 2010), based on defined criteria in the species
recovery plan. In 2014, we proposed to remove the Oregon chub from the
Federal List of Endangered and Threatened Wildlife (79 FR 7136,
February 6, 2014), based on delisting criteria in the recovery plan and
a five factor threats analysis. Threats to this species have been
largely ameliorated, with the exception of the effects of climate
change, and we do not consider such effects to be a substantial threat
to the species at this time. Therefore, we have determined that the
Oregon chub no longer meets the definition of an endangered or
threatened species under the Act. This final rule removes the Oregon
chub from the Federal List of Endangered and Threatened Wildlife. This
rule also removes the currently designated critical habitat for the
Oregon chub throughout its range.
Basis for the Regulatory Action--Under the Act, a species may be
determined to be an endangered species or threatened species because of
any of five factors: (A) The present or threatened destruction,
modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) the inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. We must consider the same factors in
delisting a species. We may delist a species if the best scientific and
commercial data indicate the species is neither endangered nor
threatened for one or more of the following reasons: (1) The species is
extinct; (2) the species has recovered and is no longer threatened or
endangered; or (3) the original scientific data used at the time the
species was classified were in error.
Threats to the Oregon chub at the time of listing in 1993, included
loss of habitat, water quality, and competition with and predation by
nonnative fishes. We reviewed all available scientific and commercial
information pertaining to the five threat factors in our status review
of the Oregon chub, and the results are summarized below.
We consider the Oregon chub to be ``recovered'' because
all substantial threats to this fish have been ameliorated and the
species is now abundant and well-distributed throughout much of its
presumed historical range.
All remaining potential threats to the species and its
habitat, with the exception of effects related to climate change, have
been ameliorated, and many populations exist on public lands managed
for fish and wildlife conservation.
We do not consider effects related to climate change to be
a substantial threat to the species at this time, and we do not expect
climate change effects to rise to the magnitude or severity such that
the species will be likely to become an endangered species within the
foreseeable future. While we recognize that climate change effects such
as rising air temperatures, reduced snowpack, and increased drought may
have potential effects to the Oregon chub and its habitat, the best
available information does not indicate that such
[[Page 9127]]
effects will significantly impact the Oregon chub or its habitat. We
expect that the Oregon chub's susceptibility to climate change effects
is low given the wide range of temperature tolerances of Oregon chub,
the range and diversity of habitats occupied by the species, and
because effects of climate change will be ameliorated by multiple
storage dams in the Willamette River Basin.
We find that delisting the Oregon chub is warranted and
thus we are removing this taxon from the Federal List of Endangered and
Threatened Wildlife.
We prepared a final post-delisting monitoring plan to
monitor the Oregon chub after delisting to verify that the species
remains secure.
Previous Federal Actions
Please refer to the proposed rule to remove the Oregon chub from
the Federal List of Endangered and Threatened Wildlife (79 FR 7136,
February 6, 2014) for a detailed description of previous Federal
actions concerning this species. This document is our final rule to
remove the Oregon chub from the Federal List of Endangered and
Threatened Wildlife.
Background
This is a final rule to remove the Oregon chub from the Federal
List of Endangered and Threatened Wildlife. It is our intent to discuss
in this final rule only those topics directly relevant to the removal
of the Oregon chub from the Federal List of Endangered and Threatened
Wildlife.
Species Information
The following section contains information updated from that
presented in the proposed rule to remove Oregon chub from the Federal
List of Endangered and Threatened Wildlife, which published in the
Federal Register on February 6, 2014 (79 FR 7136). A thorough
discussion of the species' description, population density, and
abundance is also found in the proposed rule.
Species Description and Life History--The Oregon chub is a small
minnow in the Cyprinid family. Young of the year range in length from 7
to 32 millimeters (mm) (0.3 to 1.3 inches (in)), and adults grow up to
90 mm (3.5 in) in length (Pearsons 1989, p. 17). The Oregon chub
reaches maturity at about 2 years of age (Scheerer and McDonald 2003,
p. 78) and in wild populations can live up to 9 years. Oregon chub
spawn from May through August and are not known to spawn more than once
a year.
The Oregon chub live in slack water off-channel habitats such as
beaver (Castor canadensis) ponds, oxbows, side channels, backwater
sloughs, low-gradient tributaries, and flooded marshes. These habitats
usually have little or no water flow, are dominated by silty and
organic substrate, and contain considerable aquatic vegetation
providing cover for hiding and spawning (Pearsons 1989, p. 27; Markle
et al. 1991, p. 289; Scheerer and McDonald 2000, p. 1). The average
depth of habitat used by the Oregon chub is less than 1.8 meters (m) (6
feet (ft)), and summer water temperatures typically exceed 16 degrees
Celsius (61 degrees Fahrenheit). Adult Oregon chub seek dense
vegetation for cover and frequently travel in the mid-water column in
beaver channels or along the margins of aquatic plant beds. Larval
Oregon chub congregate in shallow near-shore areas in the upper layers
of the water column, whereas juveniles venture farther from shore into
deeper areas of the water column (Pearsons 1989, p. 16). In the winter
months, Oregon chub are found buried in the detritus or concealed in
aquatic vegetation (Pearsons 1989, p. 16). Fish of similar size school
and feed together. In the early spring, Oregon chub are most active in
the warmer, shallow areas of aquatic habitats.
The Oregon chub is an obligatory sight feeder (Davis and Miller
1967, p. 32). It feeds throughout the day and stops feeding after dusk
(Pearsons 1989, p. 23). The Oregon chub feeds mostly on water column
fauna. The diet of Oregon chub adults collected in a May sample
consisted primarily of minute crustaceans including copepods,
cladocerans, and chironomid larvae (Markle et al. 1991, p. 288). The
diet of juvenile Oregon chub also consisted of minute organisms such as
rotifers and cladocerans (Pearsons 1989, p. 2).
Range--The Oregon chub is endemic to the Willamette River drainage
of western Oregon. Historical records show the Oregon chub existed as
far downstream as Oregon City and as far upstream as the town of
Oakridge. Historically a dynamic, alluvial river, the Willamette and
its tributaries created broad floodplains and braided reaches with many
side channels, sloughs, and other similar slack-water habitats that
support the Oregon chub. The Willamette is typical of river systems on
the west side of the Cascade Mountains, with the largest river flows/
floods influenced by heavy rain, or rain-on-snow events during the late
winter and spring. Snowmelt in the spring typically produces an
elongated flow peak in the spring, with decreasing flows throughout
summer.
Extensive human activities in the Willamette River Basin have
substantially reduced the floodplain habitats and altered water
temperatures, as well as the timing, duration, and magnitude of floods
in the basin. In the 1950s and 1960s, the U.S. Army Corps of Engineers
(USACE) constructed 13 large dams on many of the tributaries of the
Willamette River, with the primary purpose of flood risk reduction.
Though the Willamette River mainstem and some tributaries remain
undammed, miles of levees have also been constructed to further
increase agricultural and urban use of these former floodplain areas.
At the time of listing in 1993 (58 FR 53800, October 18, 1993),
only nine known populations of Oregon chub existed, and few estimates
existed of the number of individuals within each population. The
locations of these populations represented a small fraction (estimated
as 2 percent based on stream miles) of the species' formerly extensive
distribution within the Willamette River drainage.
Abundance and Distribution--Since we listed the Oregon chub as
endangered in 1993, the status of the species improved dramatically due
to the discovery of many new populations and successful reintroductions
within the species' historical range (Scheerer 2007, p. 97). Recently,
since we reclassified the Oregon chub to threatened status in 2010 (75
FR 21179, April 23, 2010), a substantial number of new Oregon chub
populations were discovered (34 populations) and established through
introductions (8 populations). In 2013, the Oregon Department of Fish
and Wildlife (ODFW) confirmed the existence of Oregon chub at 77
locations in the Molalla River, Luckiamute River, North and South
Santiam River, McKenzie River, Middle Fork and Coast Fork Willamette
Rivers, and several tributaries to the mainstem Willamette River
downstream of the Coast Fork and Middle Fork Willamette River
confluence (Bangs et al. 2012, pp. 7-9), including 56 naturally
occurring and 21 introduced populations. In 2013, the estimated
abundance of 41 Oregon chub populations was greater than 500 fish each,
and 23 of these populations exhibited a stable or increasing trend over
the last 7 years (Bangs et al. 2013, p. 1). The current status of
Oregon chub populations meets the goals of the species recovery plan
for delisting. The distribution of these sites is shown in Table 1.
[[Page 9128]]
Table 1--Distribution of Oregon Chub Populations Meeting Recovery Criteria for Delisting
[Bangs et al. 2013, pp. 5-8]
----------------------------------------------------------------------------------------------------------------
Number of large
Number of Number of large populations with Total estimated
Recovery subbasin populations populations (>=500 stable/increasing abundance in
adult fish) abundance trend subbasin
----------------------------------------------------------------------------------------------------------------
Santiam..................... 19 13 7 32,714
Mainstem Willamette \1\..... 26 10 6 71,840
Middle Fork Willamette...... 28 17 10 54,285
Coast Fork Willamette \2\... 4 1 0 824
-----------------------------------------------------------------------------------
Total................... 77 41 23 159,663
----------------------------------------------------------------------------------------------------------------
\1\ Includes McKenzie River subbasin.
\2\ The Coast Fork Willamette was identified as a subbasin containing Oregon chub in the recovery plan, but was
not identified as a Recovery Area.
Although certain populations of the Oregon chub remain relatively
stable from year to year, we observed substantial fluctuations in
abundance within populations. For instance, the largest known
population at Ankeny National Wildlife Refuge was 21,790 Oregon chub
individuals in 2010, and increased to 96,810 in 2011. The population
then declined from 82,800 to 47,920 between 2012 and 2013. We observed
similar substantial fluctuations in 2013, at the Dunn Wetland and at
the Hills Creek Pond populations. While substantial, these fluctuations
commonly occur, and appear natural and cyclical. For example, we
estimated the population abundance at the Dexter Reservoir Alcove
``PIT1'' site at 140 in 1995. Although annual estimated abundance
fluctuated, this population reached 1,440 estimated individuals in
2000. The population then declined to 70 individuals in 2004, and then
increased again to reach 1,370 estimated individuals in 2009 (Scheerer
et al. 2005, p. 2).
A major component of recovery efforts for the Oregon chub was
introducing the species into hydrologically isolated habitats that are
free from nonnative fish species. Twenty-one new populations were
established since 1988 (Table 2). In 2013, 14 introduced populations
existed with more than 500 Oregon chub each; 6 of these populations
exhibited a stable or increasing 7-year abundance trend (Bangs et al.
2013, p. 14).
Table 2--Introduced Oregon Chub Populations
[Bangs et al. 2013, pp. 6-8, 15]
[MS--Mainstem Willamette River, S--Santiam River, CF--Coast Fork Willamette River, and MF--Middle Fork
Willamette River]
----------------------------------------------------------------------------------------------------------------
Estimated
Site name Subbasin Year of first Number of fish abundance
introduction introduced (2013)
----------------------------------------------------------------------------------------------------------------
Dunn Wetland............................ MS.................... 1997 573 6,439
Finley Display Pond..................... MS.................... 1998 500 118
Russell Pond............................ MS.................... 2001 500 133
Finley Cheadle Pond..................... MS.................... 2002 530 157
Ankeny Willow Marsh..................... MS.................... 2004 500 47,920
St. Paul Ponds.......................... MS.................... 2008 195 442
Finley-Buford Pond...................... MS.................... 2011 160 1,009
Murphy Pond............................. MS.................... 2011 214 1,079
Ellison Pond............................ MS.................... 2012 110 9
McCrae Reservoir........................ MS.................... 2013 29 29
Foster Pullout Pond..................... S..................... 1999 500 3,412
South Stayton Pond...................... S..................... 2006 439 1,102
North Stayton Pond...................... S..................... 2010 620 3,724
Budeau South Pond....................... S..................... 2010 312 2,810
Budeau North Pond....................... S..................... 2010 310 8,350
Herman Pond............................. CF.................... 2002 400 184
Sprick Pond............................. CF.................... 2008 65 608
Wicopee Pond............................ MF.................... 1992 178 4,375
Fall Creek Spillway Ponds............... MF.................... 1996 500 9,107
Haws Enhancement Pond................... MF.................... 2009 133 788
Hills Creek Pond........................ MF.................... 2010 1,127 14,613
----------------------------------------------------------------------------------------------------------------
Genetic Diversity--The Service's Abernathy Fish Technology Center
conducted a genetic analysis on the Oregon chub in 2010 (DeHaan et al.
2010, 2012, entire). The analysis examined genetic diversity at 10
microsatellite loci within and among 20 natural and 4 introduced
populations. The findings suggest that four genetically distinct groups
of the Oregon chub exist, corresponding to the four subbasins of the
Willamette River. Levels of genetic diversity were high across the
range of the species and equal to, or greater than, other threatened or
endangered species of minnows (i.e., cyprinids). In addition, the
levels of genetic diversity for Oregon chub were similar to the creek
chub Semotilus atromaculatus, a widespread and abundant species of
minnow (DeHaan 2012, pp. 548-549). Despite fluctuations in population
abundance of Oregon chub, genetic diversity remained stable
[[Page 9129]]
over a 7- to 8-year interval (three to four Oregon chub generations).
Two populations of the 24 evaluated had reduced genetic diversity: A
recent bottleneck was observed in the Shetzline population, and the
Geren Island population showed evidence of decreasing diversity,
possibly due to reductions in the population size from 8,660 to 360
fish between 1997 and 2000 (Bangs et al. 2012, p. 109). Currently, both
populations are abundant and exhibit an increasing trend in population
growth over the last 7 years (Bangs et al. 2013, pp. 7-8).
The genetic assessment (DeHaan et al. 2010, p. 18; DeHaan et al.
2012, p. 545) shows that the current Oregon chub translocation
guidelines (ODFW 2006, entire) (which require the donor population from
within same subbasin, and a minimum of 500 Oregon chub introduced) are
effective in establishing genetically viable populations. Levels of
genetic diversity were similar to natural populations in three out of
four of the introduced sites studied. Introduced populations from
multiple sources had increased diversity and showed evidence of
interbreeding. The Dunn wetland population, which had three donor
populations, had the highest genetic diversity of all sites (natural
and introduced). The Wicopee Pond population had relatively low levels
of genetic diversity, which was likely because this population was
founded with only 50 Oregon chub originating from 1 source population.
These data support introducing greater numbers of individuals and using
multiple sources from within a subbasin.
Recovery and Recovery Plan Implementation
Background--Section 4(f) of the Act (16 U.S.C. 1531 et seq.)
directs us to develop and implement recovery plans for the conservation
and survival of endangered and threatened species unless we determine
that such a plan will not promote the conservation of the species.
Under section 4(f)(1)(B)(ii), recovery plans must, to the maximum
extent practicable, include: ``Objective, measurable criteria which,
when met, would result in a determination, in accordance with the
provisions of [section 4 of the Act], that the species be removed from
the list.'' However, revisions to the list (adding, removing, or
reclassifying a species) must reflect determinations made in accordance
with sections 4(a)(1) and 4(b) of the Act. Section 4(a)(1) requires
that the Secretary determine whether a species is endangered or
threatened (or not) because of one or more of five threat factors.
Section 4(b) of the Act requires that the determination be made
``solely on the basis of the best scientific and commercial data
available.'' Therefore, recovery criteria should help indicate when we
would anticipate that an analysis of the five threat factors under
section 4(a)(1) would result in a determination that the species is no
longer an endangered species or threatened species because of any of
the five statutory factors (see Summary of Factors Affecting the
Species).
While recovery plans provide important guidance to the Service,
States, and other partners on methods of minimizing threats to listed
species and measurable objectives against which to measure progress
towards recovery, they are not regulatory documents and cannot
substitute for the determinations and promulgation of regulations
required under section 4(a)(1) of the Act. A decision to revise the
status of or remove a species from the Federal List of Endangered and
Threatened Wildlife (50 CFR 17.11) is ultimately based on an analysis
of the best scientific and commercial data then available to determine
whether a species is no longer an endangered species or a threatened
species, regardless of whether that information differs from the
recovery plan.
Recovery plans may be revised to address continuing or new threats
to the species, as new, substantive information becomes available. The
recovery plan identifies site-specific management actions that will
achieve recovery of the species, measurable criteria that set a trigger
for review of the species' status, and methods for monitoring recovery
progress. Recovery plans are intended to establish goals for long-term
conservation of listed species and define criteria that are designed to
indicate when the substantial threats facing a species have been
removed or reduced to such an extent that the species may no longer
need the protections of the Act.
There are many paths to accomplishing recovery of a species, and
recovery may be achieved without all criteria being fully met. For
example, one or more criteria may be exceeded while other criteria may
not yet be accomplished. In that instance, we may determine that the
threats are minimized sufficiently and the species is robust enough to
delist. In other cases, recovery opportunities may be discovered that
were not known when the recovery plan was finalized. These
opportunities may be used instead of methods identified in the recovery
plan. Likewise, information on the species may be discovered that was
not known at the time the recovery plan was finalized. The new
information may change the extent to which criteria need to be met for
recognizing recovery of the species. Recovery of a species is a dynamic
process requiring adaptive management that may, or may not, fully
follow the guidance provided in a recovery plan.
Recovery Planning--The Oregon Chub Working Group, which was formed
prior to listing the species, is a proactive force in improving the
conservation status of the Oregon chub. This group of Federal and State
agency biologists, academicians, land managers, and others has met each
year since 1991, to share information on the status of the Oregon chub,
results of new research, and ongoing threats to the species.
Additionally, an interagency conservation agreement was established for
the Oregon chub in 1992 (ODFW et al. 1992). The objectives of the
agreement were to: (1) Establish a task force drawn from participating
agencies to oversee and coordinate Oregon chub conservation and
management actions; (2) protect existing populations; (3) establish new
populations; and (4) foster greater public understanding of the
species, its status, and the factors that influence it (ODFW et al.
1992, pp. 3-5). These objectives are similar to that of the
subsequently developed recovery plan.
The Recovery Plan for the Oregon Chub was approved by the Service
on September 3, 1998 (Service 1998). The recovery plan outlines
recovery criteria to assist in determining when the Oregon chub has
recovered to the point that the protections afforded by the Act are no
longer needed. These delisting criteria are: (1) 20 populations of at
least 500 individuals each are established and maintained; (2) all of
these populations must exhibit a stable or increasing trend for 7
years; (3) at least 4 populations (meeting criteria 1 and 2) must be
located in each of the 3 subbasins (Mainstem Willamette, Middle Fork
Willamette, and Santiam Rivers); and (4) management of these 20
populations must be guaranteed in perpetuity (Service 1998, pp. 27-28).
Recovery Plan Implementation--The status of the Oregon chub has
improved dramatically since it was listed as endangered. The
improvement is due largely to the implementation of actions identified
in the interagency conservation agreement and the Oregon chub recovery
plan. These actions include the establishment of additional populations
via successful introductions within the species' historical range and
the discovery of many new populations as a result of the ODFW's surveys
of the basin (Scheerer 2007, p. 97). Over 20
[[Page 9130]]
years have passed since the species was listed, and it is now abundant
and well-distributed throughout much of its presumed historical range.
Currently, there are 77 Oregon chub populations, of which 41 have more
than 500 adults (Bangs et al. 2013, pp. 5-11). The risk of extinction
is substantially reduced as threats have been ameliorated and new
populations have been discovered or established. The following criteria
for delisting the Oregon chub are met or exceeded as described in the
recovery plan:
Delisting Criterion 1: 20 populations of at least 500 individuals
are established and maintained. This criterion was exceeded; in 2013,
we identified 41 populations with more than 500 adult Oregon chub (see
Table 1, above).
Delisting Criterion 2: All of these populations (20) must exhibit a
stable or increasing trend for 7 years. This criterion was met.
Currently, 23 populations of at least 500 individuals exhibit a stable
or increasing trend for 7 years (see Table 1, above).
Delisting Criterion 3: At least four populations (meeting criteria
1 and 2) must be located in each of the three subbasins (Mainstem
Willamette, Middle Fork, and Santiam Rivers). This criterion was
exceeded in all three subbasins. Six populations in the Mainstem
Willamette River subbasin, 10 populations in the Middle Fork Willamette
River subbasin, and 7 populations in the Santiam River subbasin meet
the first 3 delisting criteria (see Table 1, above).
Delisting Criterion 4: Management of these 20 populations must be
guaranteed in perpetuity. The level of management protection
recommended in the Oregon chub recovery plan (i.e., management
guaranteed into perpetuity) exceeds the requirements of the Act in
evaluating whether a species meets the statutory definition of
endangered or threatened, as adequate protection for the species in the
long term may be provided otherwise. Although we do not have guarantees
that all of the populations will be managed into perpetuity, we have a
high level of confidence that management of the Oregon chub sites will
continue to provide adequate protection for the species in the long
term, as further discussed below. Of the 41 sites with populations of
more than 500 Oregon chub, 28 of the sites are in public or Tribal
ownership, with either active conservation management programs, or
practices where land managers consider the needs of the Oregon chub
when implementing site management activities. Additionally, eight of
the sites with abundant populations of the Oregon chub are on land that
is privately owned, either where landowners have signed conservation
agreements or are enrolled in our Safe Harbor Program. Three additional
sites are on land that is in a permanent easement or ownership by the
McKenzie River Trust, a land trust dedicated to conservation of wetland
and riparian habitat.
Based on our review of the Oregon chub recovery plan, we conclude
that the status of the species has improved due to implementation of
recovery activities and the objectives of the recovery plan have been
met. Our analysis of whether the species has achieved recovery and thus
no longer requires the protections of the Act because it is no longer
an endangered or threatened species is based on the five statutory
threat factors identified in section 4 of the Act, and discussed below
in the Summary of Factors Affecting the Species.
Summary of Comments and Recommendations
In the proposed rule published February 6, 2014 (79 FR 7136), we
requested that all interested parties submit written comments on the
proposal by April 7, 2014. We also contacted appropriate Federal and
State agencies, scientific experts and organizations, and other
interested parties and invited them to comment on the proposal. The
Service hosted a media event with local and national news coverage
announcing the proposed rule on February 4, 2014. We did not receive
any requests for a public hearing.
During the comment period for the proposed rule, we received five
comment letters (three from peer reviewers, one from the ODFW, and one
from the public) directly addressing the proposed removal of the Oregon
chub from the Federal List of Endangered and Threatened Wildlife. All
substantive information provided during the comment period is either
incorporated directly into this final determination or is addressed
below. The following section summarizes issues and information we
consider to be substantive from peer review and public comments, and
provides our responses.
Peer Review
In accordance with our policy, ``Notice of Interagency Cooperative
Policy for Peer Review in Endangered Species Act Activities,'' which
was published on July 1, 1994 (59 FR 34270), we solicited expert
opinion on the proposed rule and the draft post-delisting monitoring
plan from three knowledgeable independent individuals with scientific
expertise that included familiarity with Oregon chub and its habitat,
biological needs, recovery efforts, and threats. We received responses
from all three peer reviewers. Issues and information provided by the
peer reviewers are summarized in the Peer Reviewer Comments section,
and where they overlap with similar issues identified by the public,
they are included in the Public Comments section.
Peer Reviewer Comments
Comment (1): Two peer reviewers suggested that the lower bounds of
the confidence intervals should be used to determine the number of
populations meeting Delisting Criterion #1.
Our response: The species' recovery plan does not define the method
to determine population size for Delisting Criterion #1. The ODFW uses
a single-sample mark-recapture model, also called an adjusted Petersen
estimate, to estimate population abundance (Bangs et al. 2013, p. 5).
This method is supported in the literature (Seber 1973, pp. 59-60,
Ricker 1975, pp. 75-79), and demonstrates reliable estimates for
sampling conditions similar to what ODFW experiences monitoring Oregon
chub. The ODFW also demonstrates the reliability in its population
abundance estimates by providing a 95 percent confidence interval
(Bangs et al. 2013, pp. 9-12). The calculation of the confidence
interval is highly influenced by the sample size; a narrower interval
requires sampling more individuals (Seber 1973, p. 61). Thus, in small
populations, greater sampling effort would be required to demonstrate
if a population met Delisting Criterion #1 if the lower bound was used,
thus exposing more individuals to the risk of trapping or handling
mortality. We do not agree with the reviewer's suggestion to use the
lower bound of the 95 percent confidence interval, as this method
exposes individuals in small populations to greater risk of mortality
than the method used by the ODFW.
Comment (2): One peer reviewer asked why the Coast Fork Willamette
Oregon chub populations were not mentioned under Delisting Criterion
#3.
Our response: Under the recovery plan for Oregon chub, the Coast
Fork Willamette was not included in the Mainstem, Santiam, or Middle
Fork Willamette recovery areas. The recovery plan states: ``Although a
single small population of Oregon chub currently occurs in a fourth
subbasin, the Coast Fork, recovery efforts will not focus on this
subbasin because surveys have not
[[Page 9131]]
revealed any other suitable habitats, and nonnative fish are very
common.'' Although we are encouraged that two additional, small
populations of Oregon chub were discovered and two introduced
populations were established in the Coast Fork subbasin, recovery
criteria were met without the inclusion of the populations in this
subbasin.
Comment (3): One peer reviewer asked that the Service provide a
more current summary of the 2009-2010 Willamette Floodplain Report
(Bangs et al. 2011a, entire). This peer reviewer also suggested that
the delisting rule incorporate 2013 data.
Our response: The Willamette Floodplain Report, with analysis of
data from 2009-2012, is currently in preparation by the ODFW, and is
expected to be available late spring 2015 at the earliest. As such, we
are using the best available information at this time. We agree with
the second part of this comment, and updated the rule to include the
2013 data.
Public Comments
Comment (4): One commenter stated that the Service did not
adequately consider effective population size in the decision to delist
the Oregon chub. The commenter stated that the general rule for short-
term (50) and long-term (500) effective population size is not
appropriate, as an effective population size of 500 individuals does
not sufficiently reduce extinction risk. The commenter stated that
determining a minimum viable population based on effective population
size should include additional factors, such as environmental and
demographic stochasticity, spatial dispersion, overlapping generations,
and synergistic interactions among the risk factors. As an example, the
commenter mentioned that the largest population of Oregon chub in the
Middle Fork Willamette subbasin is in Hills Creek Pond; the population
abundance was estimated at 13,460 individuals in 2012. The commenter
noted that this was the total population size and not the effective
population size, and was too small to assure viability.
Our response: The minimum viable population is the smallest
estimated population size with a high probability of long-term
persistence. Minimum viable population factors in risks associated with
demographic and environmental stochastic events, and the impacts of
inbreeding and limited genetic diversity. The effective population size
is the number of breeding individuals in the population that contribute
genetic material to the next generation, and can be used to determine
the impacts of inbreeding and limited genetic diversity during the
analysis of the minimum viable population. The recovery criteria in the
recovery plan (Service 1998) do not require measuring effective
population sizes for Oregon chub. At the time the recovery plan was
written, the Service used the best available science to set the
recovery criterion abundance threshold at 500 adult fish per
population. This threshold is based on the total adult population size,
not effective population size, and takes into account effects of
limited genetic diversity and inbreeding associated with small
population size and the risk associated with stochastic events.
Jamieson and Allendorf (2012, p. 583) suggested that, at a minimum,
an effective population size of 500 individuals is needed for
conservation of endangered species, including the potential impacts of
stochastic events on conservation genetics. Jamieson and Allendorf
(2012, p. 580) suggested an effective population size of 500
individuals is the total for all populations of a species, and not the
size of individual populations. The total Oregon chub population size
in 2013 was approximately 160,000 adult fish (Bangs et al. 2013, pp. 6-
9).
DeHaan (2012, p. 543) determined effective population size for
three isolated Oregon chub populations as part of a genetic analysis of
the species. While these isolated populations represent a worst-case
scenario for negative genetic effects, the study suggested: (1) There
was no immediate threat from inbreeding or genetic drift, and (2) many
Oregon chub populations have some degree of connectivity to other
populations. This study also determined that genetic diversity remains
high and stable over time, despite fluctuations in individual
population size. Further, the ODFW (Bangs et al. 2013, p. 17)
documented movement of individual Oregon chub between populations,
which provides a mechanism for genetic exchange between populations
that will maintain genetic variation (DeHaan 2012, p. 543). Despite the
recent genetic analysis (DeHaan 2012, p. 543), the best available
information is not sufficient to determine a minimum viable population
size for Oregon chub.
In our decision to delist the Oregon chub, we are required to
analyze the current or foreseeable threats to the species to determine
whether a species meets the definition of endangered or of threatened,
based on the best available scientific information. Our analysis
includes recent genetic data that demonstrate Oregon chub are not
threatened by low genetic diversity. We conclude that the recovery
criterion abundance threshold of 500 adult fish per population is
adequate, and analyzing the effective population size or determining
the minimum viable population is not required in order to assess the
status of the species.
Comment (5): One commenter stated that the Service was not
conservative in the analysis of population size and must err on the
side of caution. The reviewer commented that stochastic events and
small population sizes decreases the population viability and increases
the extinction risk of Oregon chub. The commenter further stated that
the extreme annual variability within individual Oregon chub population
sizes suggests considerable risk of extinction, even in locally
abundant populations. The commenter mentioned that in addition,
population growth is impacted by demographic stochasticity.
Our response: We disagree. The Act does not require that we ``err
on the side of caution'' in determining the status of a species; it
requires that we determine, based on the best available scientific
information, whether a species meets the definition of endangered or of
threatened. The Willamette River floodplain where Oregon chub evolved
has always been highly dynamic. Oregon chub are extremely well adapted
to surviving stochastic events. For instance, Oregon chub habitats have
been known to freeze each winter, experience high magnitude flood flows
in the spring, and reach in excess of 25 degrees Celsius (77 degrees
Fahrenheit) in the summer, yet Oregon chub survive. Oregon chub are now
well-distributed throughout their historical range in a variety of
habitats, which reduces the risk of effects of severe stochastic events
to the species throughout its range. Each habitat is impacted by
stochastic effects in different ways. For example, while populations in
shallow water habitats with high solar exposure may be impacted by
severe hot and dry weather that raises temperatures to unsuitable
levels for chub, populations in habitats that are deep and well-shaded
may benefit by water warmed to the preferred temperature range for the
species. Oregon chub have been documented in new, suitable habitat
created by floodplain processes in the McKenzie River subbasin, and
voluntary movement of Oregon chub was documented between populations in
the Middle Fork Willamette River (Bangs et al. 2012, p. 19) and
McKenzie River subbasins (Bangs et al. 2013, p. 17). These findings
demonstrate the ability
[[Page 9132]]
of Oregon chub to colonize new habitats, resulting in exchange of
genetic material between established populations, thus reducing the
potential effects of stochastic events on small populations.
Further, for each ``stable'' population (as defined in the recovery
plan), we calculate the coefficient of variation for the past 7 years.
If the coefficient of variation is greater than one (in other words, if
the variation is greater than the mean abundance), we consider the
population ``unstable'' and do not consider that population to meet the
recovery criteria. The 20 populations in 2012, and 23 populations in
2013, that met delisting criteria had either a ``stable'' or
``increasing'' abundance trend. This leads us to conclude that the
variability in population abundance is not a factor that will impact
future survival of these populations, provided the abundance criteria
(500 adult fish) is met, because genetic diversity remains high and
stable over time, despite fluctuations in individual population size
(DeHaan 2012, p. 543). Overall, trend analysis conducted since 1996
demonstrates that the Oregon chub populations are stable and that the
concerns raised by the commenter are not affecting Oregon chub recovery
and are not expected into the foreseeable future.
Comment (6): One commenter and one peer reviewer suggested
including a better description of population trends for Oregon chub
populations that are coexisting with nonnative predators. One peer
reviewer also suggested that the Service discuss specific predators
that may impact Oregon chub, instead of combining all nonnatives,
specifically western mosquitofish (Gambusia affinis) and largemouth
bass (Micropterus salmoides). One peer reviewer suggested that the
Service include western mosquitofish as a potential predator on larval
Oregon chub, and that we include this species in the predation
discussion. One commenter recommended that efforts to limit largemouth
bass colonization should be discussed in the final rule to delist
Oregon chub. The peer reviewer asked that the Service explore
alternative management of mosquitoes by using native minnows instead of
nonnative western mosquitofish. One commenter stated that the
inadequacy of existing regulatory mechanisms to prevent spread of
western mosquitofish and largemouth bass into connected watersheds was
not adequately analyzed, and should be discussed. Additionally, one
peer reviewer recommended that the post-delisting monitoring (PDM) plan
focus on specific nonnative species of concern (mosquitofish and
largemouth bass).
Our response: The best available data show no relationship between
the presence of nonnative fish and Oregon chub population abundance
trends (Bangs et al. 2013, p. 17). Thirteen of the 23 populations that
met delisting criteria with either a stable or increasing abundance
trend in 2013 occur with nonnative fish; 1 of the 2 populations that
had a declining abundance trend occurs with nonnative fish (Bangs et
al. 2013, p. 17). Nonnative fish that are thought to have the potential
to impact Oregon chub populations through predation and competition
include largemouth bass, smallmouth bass (Micropterus dolomieu),
bluegill (Lepomis macrochirus), pumpkinseed sunfish (Lepomis gibbosus),
warmouth (Lepomis gulosus), green sunfish (Lepomis cyanellus), yellow
perch (Perca flavescens), walleye (Sander vitreus), black crappie
(Pomoxis nigromaculatus), white crappie (Pomoxis annularis), common
carp (Cyprinus carpio), brown bullhead (Ameiurus nebulosus), yellow
bullhead (Ameiurus natalis), and western mosquitofish (Markle et al.
1991, p. 91). We agree that western mosquitofish are potential
predators on larval Oregon chub, and we have included an analysis of
their impact in this final rule. While we acknowledge that some of
these fish species may represent a larger threat to individual Oregon
chub populations than others, we maintain that monitoring should
include all nonnative species. We determine in the five factor analysis
(see Factors A, C, and E) that the threats of nonnative fish to the
Oregon chub have been ameliorated; thus, there is no existing or
potential future significant threat that is inadequately addressed
through existing regulatory mechanisms (see Factor D). Additionally, a
regulatory mechanism is in place to prevent the translocation of
nonnative fish. Within the State of Oregon, it is unlawful to
transport, release, or attempt to release any live fish into the waters
of this State (Oregon Administrative Rules (OAR) 635-007-0600). Abiotic
factors such as water flow through connected habitats and variability
in water temperature and depth keep largemouth bass and nonnative
predators from becoming dominant in these habitats. Through the PDM,
the ODFW will continue to monitor Oregon chub populations that are
thriving, despite the presence of nonnative fish, to better understand
the factors that allow this to occur. While we support efforts to limit
the proliferation of nonnative fish in the Willamette River Basin,
creating a management action for nonnative fish or addressing vector
control guidelines is outside the scope of this rule and the PDM plan.
Comment (7): Two peer reviewers and one public commenter discussed
the need to consider the effects of climate change, environmental
stochasticity, human population growth, and resulting changes in water
availability on the viability and vulnerability of Oregon chub
populations and suitable habitats. Primary concerns included effects to
Oregon chub from: Extreme climatic variation (including drought
effects, effects to instream flows, and increased reservoir drawdown);
water temperature increases and reduced cool water refugia; the
potential reduction in habitat size and quality; habitat fragmentation;
and likely increases in populations of predatory and competitor
nonnative fish species.
Our response: The Service reviews the best scientific and
commercial information available when conducting a threats analysis. In
considering what factors might constitute a threat we must look beyond
the mere exposure of the species to the factor to determine whether the
exposure causes actual impacts to the species. The mere identification
of factors that could negatively impact a species is not sufficient to
compel a finding that listing (or maintaining a currently listed
species on the Federal Lists of Endangered or Threatened Wildlife or
Plants) is appropriate. We require evidence that these factors are
operative threats currently acting on the species to the point that the
species meets the definition of endangered or of threatened under the
Act.
The Service acknowledges that environmental changes could occur
over the next several decades due to both climate change effects and
human population growth. However, it is difficult to: (1) Predict with
any certainty how those changes may influence Oregon chub populations
and their habitats in the Willamette Valley, and (2) accurately
describe and assess the net effects when considering the potential
negative consequences together with the potential positive consequences
to Oregon chub populations. Additional information and explanation was
added to this final rule in the section on ``Effects Related to Climate
Change'' (see Factor A).
Comment (8): One commenter stated that if Oregon chub are delisted,
the terms and conditions required under the Service's biological
opinion issued under section 7 of the Act to the USACE and other
Federal agencies on the
[[Page 9133]]
continued operation and maintenance of dams in the Willamette River
Basin will no longer be required, thereby removing key protections for
the Oregon chub. This commenter also expressed a concern that delisting
will eliminate consultation and agency review of actions permitted via
the USACE permit program.
Our response: Since 2002, the USACE has implemented minimum dam
outflow targets that sustain downstream floodplain habitat, which has
reduced the threat of habitat loss for the Oregon chub. These minimum
flow targets will continue to be required into the future, even after
the Oregon chub is delisted, under existing biological opinions from
the Service and National Marine Fisheries Service (NMFS) on the USACE's
Willamette Valley Project (Service 2008b, pp. 40-51; NMFS 2008, pp. 2-
43 to 2-52), because these biological opinions apply to other listed
fish species (Upper Willamette spring chinook salmon (Oncorhynchus
tshawytscha), Upper Willamette winter steelhead (Oncorhynchus mykiss),
and bull trout (Salvelinus confluentus)). The USACE also has a
memorandum of understanding (MOU) with The Nature Conservancy's (TNC)
Sustainable Rivers Project, an ongoing collaboration to promote
ecologically sustainable flows below USACE dams in the Willamette River
Basin (USACE and TNC 2000, 2011; entire). For these reasons, we
anticipate that the USACE will continue to meet these minimum flow
targets after delisting of the Oregon chub. Also, the acquisition of
floodplain habitat for long-term conservation and restoration,
including off-channel locations preferred by the Oregon chub, has
gained momentum in the Willamette River Basin by a variety of Federal,
State, Tribal, local governmental, and nongovernmental agencies, which
provides assurances that Oregon chub habitat will continue to be
managed for the species. Given the MOU between the USACE and TNC
regarding the Sustainable Rivers Project, and the minimum flows
required under two existing biological opinions (NMFS 2008, pp. 2-43 to
2-52; Service 2008b, pp. 40-51) for bull trout, Upper Willamette spring
chinook, Upper Willamette winter steelhead, and their designated
critical habitats, we anticipate that flow management trending towards
natural flow regimes below Willamette Project dams will continue to
create and rejuvenate off-channel habitats to the benefit of the Oregon
chub into the foreseeable future.
The USACE permits in-water work including construction and dredging
in navigable waters under section 404 of the Clean Water Act (CWA; 33
U.S.C. 1251 et seq.). While we acknowledge that consultation under
section 7 of the Act will no longer be required for Oregon chub, the
Service will continue to provide comments to the USACE on individual
section 404 permits in the Willamette Valley through our authorities
under the Fish and Wildlife Coordination Act (16 U.S.C. 661 et seq.).
The USACE routinely sends the Service individual permit applications
for our review, and we provide specific comments and recommendations to
reduce negative effects to fish and wildlife, including unlisted
species. For most section 404 projects, any potential negative impacts
to habitat and species are generally short-term. While in-water work
has the potential to impact individual Oregon chub populations, this
impact for the overall population is considered a low risk because the
species is widely distributed across multiple subbasins with many
abundant populations. In the past 4 years, we have received
approximately 13 such requests to review section 404 permits from the
USACE. Of those 13 projects, we found that 9 were not likely to
adversely affect Oregon chub and 2 projects only required technical
assistance; we completed 1 formal consultation for a river restoration
study that only anticipated short-term effects and long-term benefits.
The last project was an emergency consultation when the USACE had to
take action to maintain water levels in Oregon chub habitat on their
property, as the habitat was affected by atypical, unexpected
operations necessary for dam safety. The USACE worked with the ODFW to
introduce Oregon chub into Hills Creek Pond during the drawdown as a
back-up to the Dexter RV Park Pond ``DEX3'' and the Dexter Reservoir
Alcove ``PIT1'' populations, in case either population failed during
the drawdown.
Comment (9): One commenter stated that there are no regulatory
mechanisms to protect Oregon chub habitat in the floodplain habitats
that have been acquired for long-term conservation and restoration.
Our response: We disagree. One of the factors identified as a
threat to Oregon chub at the time of listing was habitat loss. This
threat has been ameliorated by the actions of multiple conservation
partners over the last 20 years. In 2010, the Bonneville Power
Administration (BPA) and the State of Oregon signed the Willamette
River Basin Memorandum of Agreement Regarding Wildlife Habitat
Protection and Enhancement (BPA and ODFW 2010, entire). The Agreement
established goals for mitigating the effects of the construction,
inundation, and operation of the Willamette River Basin Flood Control
Projects in the Willamette Valley. Under the terms of the Agreement,
the State of Oregon and the BPA agreed to acquire at least an
additional 16,880 acres (ac) (6,831 hectares (ha)) of wildlife
mitigation property to protect 26,537 ac (10,739 ha) (or more) by the
end of 2025. Throughout the Willamette River Basin, floodplain
properties have been, and will continue to be, acquired. All habitat
acquisitions funded by the BPA must include provisions for permanent
protections and enforcement of those protections. The acquisition of
floodplain habitat for long-term conservation and restoration through
these mechanisms provides assurances that Oregon chub habitats will
continue to be managed for the species into the foreseeable future.
Summary of Factors Affecting the Species
This section contains updated information and associated analysis
from that presented in the proposed rule (79 FR 7136, February 6,
2014). Updated information includes data collected during the 2013
field season (Bangs et al. 2013, entire) and additional information
requested by peer and public reviewers.
Section 4 of the Act and its implementing regulations (50 CFR part
424) set forth the procedures for listing species, reclassifying
species, or removing species from listed status. ``Species'' is defined
by the Act as including any species or subspecies of fish or wildlife
or plants, and any distinct vertebrate population segment of fish or
wildlife that interbreeds when mature (16 U.S.C. 1532(16)). A species
may be determined to be an endangered or threatened species due to one
or more of the five factors described in section 4(a)(1) of the Act:
(A) The present or threatened destruction, modification, or curtailment
of its habitat or range; (B) overutilization for commercial,
recreational, scientific, or educational purposes; (C) disease or
predation; (D) the inadequacy of existing regulatory mechanisms; or (E)
other natural or manmade factors affecting its continued existence. We
must consider these same five factors in delisting a species. We may
delist a species according to 50 CFR 424.11(d) if the best available
scientific and commercial data indicate that the species is neither
endangered nor threatened for the following reasons: (1) The species is
extinct; (2) the species has recovered and is no longer endangered or
threatened (as is the case with the Oregon chub); and/or (3) the
[[Page 9134]]
original scientific data used at the time the species was classified
were in error.
A recovered species is one that no longer meets the Act's
definition of endangered or of threatened. Determining whether the
status of a species has improved to the point that it can be delisted
or downlisted requires consideration of whether the species is
endangered or threatened because of the same five categories of threats
specified in section 4(a)(1) of the Act. For species that are already
listed as endangered or threatened, this analysis of threats is an
evaluation of both the substantial threats currently facing the species
and the threats that are reasonably likely to affect the species in the
foreseeable future following the delisting or downlisting and the
removal or reduction of the Act's protections.
A species is an ``endangered species'' for purposes of the Act if
it is in danger of extinction throughout all or a ``significant portion
of its range'' and is a ``threatened species'' if it is likely to
become endangered within the foreseeable future throughout all or a
``significant portion of its range.'' The word ``range'' in the
significant portion of its range phrase refers to the range in which
the species currently exists. For the purposes of this analysis, we
will first evaluate whether the currently listed species, the Oregon
chub, should be considered endangered or threatened throughout all its
range. Then we will consider whether there are any significant portions
of the Oregon chub's range where the species is in danger of extinction
or likely to become so within the foreseeable future.
The Act does not define the term ``foreseeable future.'' For the
purpose of this rule, we define the ``foreseeable future'' to be the
extent to which, given the amount and substance of available data, we
can anticipate events or effects, or reliably extrapolate threat
trends, such that we reasonably believe that reliable predictions can
be made concerning the future as it relates to the status of the Oregon
chub. In considering the foreseeable future as it relates to the status
of the Oregon chub, we considered the factors affecting the Oregon
chub, historical abundance trends, and ongoing conservation efforts.
The following analysis examines all five factors currently
affecting, or that are likely to affect, the Oregon chub within the
foreseeable future.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
When the Oregon chub was listed as endangered in 1993, the species
was known to exist at nine locations, representing only 2 percent of
the species' historical range (Markle 1991, pp. 288-289; Scheerer et
al. 2007, p. 2; 58 FR 53800, October 18, 1993, p. 53800). The decline
in Oregon chub abundance and distribution was attributed to the
extensive channelization, dam construction, and chemical contamination
that occurred in the Willamette River Basin, particularly from the
1940s through the late 20th century (Pearsons 1989, pp. 29-30).
Since listing, concerted efforts by Federal, State, and local
governments and private landowners have greatly reduced the threats to
the Oregon chub. For example, the introduction of the Oregon chub into
secure habitats has created refugial populations in habitats that are
isolated from the threats of habitat loss and invasion by nonnative
fishes. Additionally, as explained below, research has expanded our
understanding of suitable habitat for the Oregon chub, and increased
survey efforts have led to the discovery of many natural populations.
Since 2002, the USACE has implemented minimum dam outflow targets that
sustain downstream floodplain habitat, which has reduced the threat of
habitat loss for the Oregon chub. These minimum flow targets will
continue to be required into the future under existing biological
opinions from the Service and NMFS on the USACE's Willamette River
Basin Project (see description below). The USACE also has a MOU with
TNC regarding the Sustainable Rivers Project, an ongoing collaboration
to promote ecologically sustainable flows below USACE dams in the
Willamette River Basin. For these reasons, we anticipate that the USACE
will continue to meet these minimum flow targets after delisting of the
Oregon chub. Also, the acquisition of floodplain habitat for long-term
conservation and restoration, including off-channel locations preferred
by the Oregon chub, has gained momentum in the Willamette River Basin
by a variety of Federal, State, Tribal, local governmental and
nongovernmental agencies, which provides assurances that Oregon chub
habitat will continue to be managed for the species.
Since 1992, the Oregon chub was introduced and established in 21
secure, isolated habitats (Bangs et al. 2013, p. 15). These populations
contribute to recovery by providing redundancy to the naturally
occurring populations, increasing the abundance of the Oregon chub in
each recovery area, and providing refugial habitat that is less
vulnerable, as compared to connected habitats, to the threats of
habitat loss and invasion by nonnative fishes. The majority of Oregon
chub individuals occur in populations at these introduction sites. In
2013, we estimated 106,408 Oregon chub in the 21 introduced
populations. By contrast, we estimated 53,255 Oregon chub in the 56
naturally occurring populations. Eleven of the introduction sites are
in public ownership by Federal and State agencies that manage these
sites for conservation of the Oregon chub, and we have no information
that suggest these sites would be managed otherwise into the
foreseeable future.
The remaining 10 introduction sites are privately owned. Many of
these introduction sites were created or restored under the Service's
Partners for Fish and Wildlife Program managed by the staff of the
Willamette Valley National Wildlife Refuge Complex. Most of these
landowners have either signed conservation agreements or are
participating in our Safe Harbor Program. In the interest of conserving
the Oregon chub, our Safe Harbor Program participants volunteered to
allow the introduction of the Oregon chub into ponds on their land, and
signed management plans called cooperative agreements, which are
designed to protect the species and its habitat. In exchange, the
landowners received an incidental take permit that extended an
exemption from take prohibitions under section 9 of the Act. If the
Oregon chub is delisted, the species will no longer be protected under
these take prohibitions and the incidental take permit associated with
the safe harbor agreements will no longer be in effect. This means that
landowners will no longer be legally bound to protect the species on
their property. However, we anticipate, based on their past interest
and cooperation in protecting the species, that most or all of these
landowners will continue to manage their land for conservation of the
Oregon chub into the future as described in their cooperative
agreements. We will also seek to extend these agreements beyond their
initial 10-year time period and, in the event the property is later
sold or transferred, we will work with the future landowners to enroll
them in a cooperative agreement.
In 2013, 20 of the 23 populations that met the recovery plan
criteria for delisting were located on State, Federal, Tribal, or other
property managed for long-term conservation; 3 populations were located
on privately owned property. The close knit working relationship with
private landowners is extremely important for the recovery of
[[Page 9135]]
Oregon chub; 40 percent of all Oregon chub populations exist on
privately owned property. We see no reason why the conservation efforts
of landowners would cease after delisting, as all efforts have been
voluntary. There are an additional 9 recently discovered or introduced
populations that exist on public lands with abundances greater than 500
adult Oregon chub, further supporting our determination to delist the
species.
In the 2008 5-year review of the status of the Oregon chub (Service
2008a, p. 26), we identified concerns about the ability to achieve
recovery due to the focus on managing primarily isolated populations
with limited genetic exchange. To reduce threats associated with
habitat isolation, we suggested that future recovery efforts should
integrate habitat that is connected to the floodplain. Successful
efforts to integrate floodplain habitat into Oregon chub recovery were
facilitated in part through consultation with several Federal agencies
under section 7 of the Act. Specifically, in 2008, the Service and the
NMFS completed consultation with the USACE, BPA, and the Bureau of
Reclamation under section 7 of the Act on the continued operation and
maintenance of 13 large flood-control dams in the Willamette River
Basin, collectively known as the Willamette River Basin Project
(Willamette Project). The Service's biological opinion considered the
Willamette Project's effects to the Oregon chub, the bull trout, and
bull trout critical habitat (Service 2008b, entire), while the NMFS'
biological opinion considered effects to threatened salmon and
steelhead (salmonids) and associated critical habitat (NMFS 2008,
entire). The terms and conditions of the Service's biological opinion
required the USACE to fund a floodplain study that would increase our
understanding of the effects of flow management on connected downstream
Oregon chub habitat. The ODFW subsequently pursued opportunities to
study these effects and to integrate floodplain habitat in recovery
efforts, in part, through funding provided by the USACE under the terms
and conditions of the biological opinion.
The floodplain study required by the Willamette Project biological
opinion began in 2009 (Bangs et al. 2010a, p. 1). Under this study, the
ODFW sampled fish assemblages and monitored habitat conditions (i.e.,
bathymetry, pond volume, percent vegetation, water temperature) in
several off-channel habitats in the Middle Fork Willamette River
downstream of Dexter Dam in Lowell, Oregon, to Jasper, Oregon (Bangs et
al. 2010a, pp. 2-4). The ODFW chose the Dexter to Jasper reach of the
Middle Fork Willamette River as a study area because several off-
channel habitats in this reach were known to be occupied by the Oregon
chub, and the majority of the adjacent land is in public ownership and
accessible.
The ODFW sampled most of the hydrologically connected, off-channel
habitat in this reach and discovered that the Oregon chub also occupied
sites previously thought to be unsuitable. These sites contain greater
habitat complexity than sites where Oregon chub were previously known
to occur. Although these habitats have features such as beaver dams and
shallow, inundated benches that were known to provide suitable habitat
for Oregon chub, the recently discovered sites also include channels
that have frequent connectivity to the adjacent river channel (Bangs
2013, pers. comm.). Frequently connected sites such as these were
thought to be unsuitable because these sites were accessible to
nonnative fishes that prey upon or compete with the Oregon chub for
resources.
The discovery of Oregon chub in these connected sites facilitated a
better understanding of the diversity of habitats occupied by Oregon
chub, and prompted the ODFW to shift their basin-wide sampling efforts
from primarily focusing on isolated habitats or habitats with
infrequent river connection to sampling frequently connected, off-
channel habitats. They sampled similar habitat in other recovery
subbasins and found that Oregon chub also occupied many of these
frequently connected habitats. Between 2009 and 2013, the ODFW
discovered 34 additional Oregon chub populations throughout the 3
recovery subbasins (Bangs et al. 2013, pp. 6-8). In 2013, 14 of the 23
populations that met the delisting criteria were in naturally occurring
sloughs, beaver pools, and pond habitats. Fifty-six of the 77 habitats
containing Oregon chub were naturally occurring; 21 populations were
introduced. In addition, 50 Oregon chub populations are located in
habitat that experiences some level of connectivity to the adjacent
river channel. The Service has determined that the minimum aquatic area
necessary to support a population of at least 500 adult Oregon chub is
500 square meters (m\2\) (5,400 square feet (ft\2\)) (74 FR 10412,
March 10, 2009, p. 10417). Out of the 77 populations, only a single
location, Dougren Island Slough, has an aquatic area smaller than 500
m\2\ (5,400 ft\2\); the site is 400 m\2\ (4,300 ft\2\) and supported
1,700 adult Oregon chub in 2013.
Several anthropogenic and natural environmental factors, discussed
below, may continue to have effects on Oregon chub and its habitat in
the foreseeable future. Many of these factors are included in this
discussion because the Service previously identified them as threats to
the continued existence of the species in the listing and downlisting
rules. Additionally, new factors affecting the species are discussed.
Activities Related to the Willamette Project
The Oregon chub occupies 45 connected habitats that are downstream
of Willamette Project dams or adjacent to reservoirs; these habitats
are influenced by Willamette Project operations. The Willamette Project
biological opinions were signed in 2008, and continue until 2023 (NMFS
2008, p. 1-11; Service 2008b, p. 85). In addition to normal operations
of the Willamette Project, several actions required under the terms and
conditions of the biological opinions may affect Oregon chub
populations and habitat in the future.
Temperature and flow augmentation--The USACE is implementing a
number of structural and operational changes to alter flows and water
temperatures downstream of Willamette Project dams to increase survival
of federally listed salmon and steelhead (salmonids). These operational
and structural changes have resulted in downstream water temperatures
closer to that which existed prior to the construction of the dams
(i.e., river temperatures downstream of the reservoirs are now warmer
in early summer, and cooler in the late summer and early fall). The
USACE also operates to meet mainstem and tributary flow objectives
identified in the Willamette Project biological opinion to benefit
listed salmonids; these flows also benefit the Oregon chub by
sustaining floodplain habitat downstream. In addition, the USACE works
with partners in the Willamette River Basin as part of TNC's
Sustainable Rivers Project to implement a set of environmental flow
objectives designed to improve channel morphology in a manner that will
create and sustain new, and improve existing, fish habitat (Gregory et
al. 2007, p. 11).
The effects of water flow augmentation and temperature
normalization on fish communities in off-channel habitat are largely
unknown. The ODFW has a monitoring program in place (Bangs et al.
2011a, entire) to detect any negative effects on Oregon chub and its
habitat. With the delisting of Oregon chub, this monitoring
[[Page 9136]]
program, which is detailed in our PDM plan, will continue for several
years post-delisting (Service and ODFW 2013, entire). The PDM plan
identifies thresholds and responses for detecting and reacting to
significant changes in Oregon chub protected habitat, distribution, and
persistence. If declines are detected that exceed the thresholds, the
Service, in combination with other PDM participants, will investigate
causes of these declines and determine if the Oregon chub warrants
expanded monitoring, additional research, additional habitat
protection, or relisting as an endangered or threatened species under
the Act. Additional discussion about temperature and instream flows is
presented in the ``Effects of Climate Change'' section (also in Factor
A).
Reservoir drawdowns--As required in the NMFS biological opinion for
the Willamette Project, the USACE is implementing an annual complete
reservoir drawdown of Fall Creek Reservoir on the Middle Fork
Willamette River. The biological objectives of the reservoir drawdown
are to improve fish passage efficiency and survival of juvenile Chinook
salmon migrating out of Fall Creek Reservoir, and to reduce nonnative
fish populations inhabiting the Fall Creek Reservoir. This is expected
to result in reduced nonnative predation and competition with juvenile
Chinook salmon rearing in the reservoir. While reservoir drawdown
benefits Chinook salmon, there are potential negative effects to the
Oregon chub from sedimentation of Oregon chub habitats.
Willamette River Basin flood control dams inhibit the transport of
sediment downstream, causing sedimentation to occur in the reservoirs.
During a complete reservoir drawdown, released reservoir water scours
the reservoir bed and transports sediment downstream. During the
initial Fall Creek Reservoir drawdowns, a massive volume of silt, sand,
and debris was flushed, causing sediment deposition to occur in off-
channel habitats downstream of the dam. Sampling for Oregon chub
populations in the Fall Creek drainage occurred after the first
drawdown and three previously undocumented Oregon chub populations were
found. The extent to which these populations were affected is unknown
because Oregon chub were discovered at these sites after the
sedimentation occurred and we cannot determine the area of habitat or
number of Oregon chub that existed prior to the sedimentation. Fewer
than five Oregon chub were found in each of these three sites after the
sedimentation occurred. These sites experienced the accumulation of
fine sediments, perhaps beyond typical historical levels, which reduced
the amount of habitat available to Oregon chub (Bangs 2013, pers.
comm.). However, little sedimentation was observed in the few Oregon
chub habitats that occur farther downstream of the confluence of Fall
Creek and the Middle Fork Willamette River. Most of the abundant
populations of Oregon chub in off-channel habitats of the Middle Fork
Willamette River were not affected because they occur upstream of these
impacts.
Although partial drawdowns of Willamette Project reservoirs are
likely to occur in the near future, they are unlikely to result in
large volumes of sediment moving downstream because the water level
will remain above the sediment bed and little sediment will be moved.
Complete reservoir drawdowns to the extent seen at Fall Creek are not
currently planned at other reservoirs. The effects of a complete
reservoir drawdown would vary by location; it is difficult to predict
what habitat changes may occur downstream. However, any future proposal
to implement this scale of drawdown will include extensive coordination
and planning among the Service, ODFW, USACE, and other land managers.
Additionally, in cooperation with the USACE, we developed monitoring
guidance and recommended responses in the event a drawdown is planned
(Service and ODFW 2013, pp. 18-19). We do not anticipate that potential
negative impacts from reservoir drawdowns will affect the overall
status of Oregon chub. Additional discussion about reservoir drawdown
is presented in the ``Effects of Climate Change'' section (also in
Factor A).
Another concern related to drawdowns is that nonnative predatory
fishes are common in reservoir habitats. During a drawdown, these fish
are likely transported downstream, where they may invade off-channel
habitats. The risks to the Oregon chub associated with nonnative fishes
are discussed under Factors C and E, below.
Reservoir water level fluctuations--Fluctuating water levels in
Lookout Point Reservoir on the Middle Fork Willamette River may limit
the breeding success of the Oregon chub population in Hospital Pond,
which provides habitat for the species in a pool connected to the
reservoir by a culvert (Service 2008b, p. 160). Between 2001 and 2003,
the USACE, which manages Lookout Point Reservoir as part of the
Willamette Project, implemented a series of actions to protect the
population of Oregon chub in Hospital Pond. The goal was to allow the
USACE to manage the water level in Lookout Point Reservoir
independently of the water elevation in Hospital Pond. In order to
achieve this, they installed a gate on Hospital Pond's outlet culvert
and lined the porous berm between the pond and reservoir (Service 2002,
pp. 1-11). They also excavated additional areas to create more suitable
spawning habitat in the pond (Service 2003, pp. 1-3).
Despite these actions, water elevation in Hospital Pond continues
to be influenced by reservoir water levels. Hospital Pond currently
supports a large, stable population of the Oregon chub; however, future
Willamette Project operations may result in reservoir elevations that
are below the levels necessary to inundate the spawning habitat in
Hospital Pond (Service 2008b, p. 160). This reduction in spawning
habitat may result in limited breeding success for the Oregon chub in
Hospital Pond into the foreseeable future. However, the Hospital Pond
population is not critical to meeting recovery criteria because
additional surveys in the Middle Fork Willamette River subbasin have
found that the subbasin has the highest number of Oregon chub
populations (29 populations) across the range of the species.
Currently, 17 of the Oregon chub sites in this subbasin have abundant
(greater than 500 individuals) populations of the Oregon chub. This
redundancy of large populations provides additional security to the
species in the event that single populations decline.
Inability to meet minimum flow targets--During low water or drought
years, the USACE may not be able to meet the seasonal minimum water
flow targets established in the Willamette Project biological opinions.
Analysis performed by the USACE determined that from 1936 to 1999, low
flow and drought conditions occurred 9 percent and 16 percent of the
years, respectively (USACE 2007, pp. 2-45). If this occurs in the
future, it may have negative effects on Oregon chub habitat downstream
through a temporary reduction in pond volume and increased water
temperatures. Under the floodplain study, the ODFW mapped the
bathymetry (habitat depth) and installed equipment to measure pond
elevation, area, volume, and temperature in Oregon chub sites that are
influenced by Willamette Project flows. This information was used to
determine the effect that low flows may have on the extent of habitat
area available to Oregon chub. The USACE has considered these data in
managing flows and has a notification process in
[[Page 9137]]
place to coordinate with the Service and the ODFW during low water
periods before flows are reduced to levels below the minimum flow
targets. To date, except for during malfunctions and emergency
operations explained below, flows below minimum targets have been of
short duration and have not resulted in observable adverse effects to
Oregon chub populations (Bangs 2013, pers. comm.). Further, when
minimum targets cannot be met, the Service, ODFW, NMFS, and USACE
coordinate on a regular basis to discuss reduced flow releases in
advance; this coordination allows the Service to weigh in on the
magnitude of reductions and mitigate any reductions in flows that may
affect Oregon chub populations. This coordination will continue into
the future, as required by the two biological opinions, for other
listed fish species (Service 2008b, pp. 38-40; NMFS 2008, pp. 2-39 to
2-43).
Willamette Project malfunctions and emergency operations resulting
in the USACE not meeting minimum flow targets or necessitating
restrictions on reservoir pool elevations have affected Oregon chub
habitats. These incidents have been infrequent, but resulted in short-
term negative effects on a few Oregon chub populations. For instance,
in 2009, two of the three spillway gates at the USACE Big Cliff dam on
the North Santiam River failed (Bangs et al. 2010b, p. 16). While
repairing the gates, the outflow from Big Cliff Dam was reduced to
below the minimum summer flow target. Record high air temperatures
coincided with the low flow levels. Monitoring during this event
detected that three Oregon chub sites downstream were nearly desiccated
and fish mortalities were observed. Screened pumps were used to
increase the volume of water in the ponds and to reduce water
temperatures. The effects of this incident on Oregon chub populations
were short-term, and the numbers of Oregon chub in these three
populations have either increased or are exhibiting a stable trend
(Bangs et al. 2013, pp. 6-8).
The minimum flow targets protect not only the Oregon chub, but many
other native aquatic species, including listed salmonids. If the Oregon
chub is delisted, these minimum flow targets will continue to be
required under existing biological opinions from the Service and the
NMFS on the Willamette Project for listed bull trout, Chinook salmon,
and steelhead. Moreover, the USACE was proactive in implementing
recommended flows before the Willamette Project biological opinions
were completed (USACE 2007, pp. 3-19). Therefore, we anticipate that
the USACE will continue to meet these minimum flow targets after
delisting of the Oregon chub, except under infrequent, extreme
conditions such as drought.
In 2010, the USACE determined that the condition and reliability of
the spillway gates at 13 Willamette Project dams represented an
unacceptable risk to public safety (Bangs et al. 2011b, p. 16). To
mitigate this risk, the USACE proposed implementing pool elevation
restrictions at Willamette Project reservoirs to lower than normal
levels to support maintenance and repair of the spillway gates. The
imposed restrictions affected one population (Dexter Reservoir Alcove
``PIT1'' site) of Oregon chub by reducing the pond below levels
critical for Oregon chub survival. The Dexter Reservoir Alcove ``PIT1''
site had filled with sediment over the years and in consultation with
the USACE, we determined that removing some of this sediment was the
best measure to prevent desiccation of the pond. Prior to removing
sediment, the ODFW captured and relocated a total of 1,127 Oregon chub
to Hills Creek Pond, a site with perennial flow located on USACE
property at Hills Creek Dam. This site is within the historical range
of Oregon chub, but at the time was not occupied by the species. The
pond site is adjacent to the Middle Fork Willamette River and has
historically been managed by USACE staff for wildlife habitat
enhancement. The spillway gate repairs were completed, the pool
elevation restriction for Dexter Reservoir was lifted in 2011, and the
reservoir has returned to normal operations. The Oregon chub population
abundance in Dexter Reservoir Alcove ``PIT1'' site and Dexter RV Park
Pond ``DEX3'' are both currently stable and contribute towards meeting
recovery criteria for delisting (Bangs et al. 2013, p. 8). The
translocation of Oregon chub into Hills Creek Pond created a large,
secure population that is now the largest Oregon chub population within
the Middle Fork Willamette River subbasin with an estimated abundance
of 14,610 Oregon chub (Bangs et al. 2013, p. 8). Additional discussion
about minimum flow requirements is presented in the ``Effects of
Climate Change'' section (also in Factor A).
Siltation Resulting From Timber Harvest
As previously noted, Oregon chub habitats are generally associated
with low gradient floodplain habitats not generally subject to timber
harvest activities. However, there are a small number of Oregon chub
populations that exist within, or adjacent to, forested landscapes that
were, or could be, subject to adverse effects of timber harvest. These
adverse effects include siltation (deposition of fine sediment) of
stream habitats from ground-disturbing activities involved with
standard logging practices. State and private lands in Oregon are
subject to water quality as well as fish and wildlife protective
measures under the Oregon Forest Practices Act, whereas Federal lands
are subject to land and resource management plans that also provide
protective guidelines for water quality and fish and wildlife
protections. While siltation resulting from timber harvest has not been
identified as a significant threat to Oregon chub, there is at least
one instance where siltation from timber harvest may have contributed
to a decrease in habitat suitability and availability that resulted in
a drop in chub abundance.
In the 1990s, timber harvest occurred on private lands upstream of
East Fork Minnow Creek. Flood events in the watershed in 1996, 1997,
and 1998 caused accelerated siltation into East Fork Minnow Creek Pond,
a pond downstream that is occupied by Oregon chub, and over half of the
habitat was lost (Scheerer 2009, pers. comm.). The Oregon chub
population in East Fork Minnow Creek Pond declined dramatically
following these events (Scheerer 2009, pers. comm.). In 2010, the
Oregon Department of Transportation excavated accumulated sediment in
the pond and created a pool that will provide a buffer from the effects
of future siltation. The population subsequently rebounded and it now
meets the delisting criterion for a stable or increasing trend over 7
years.
In 2012, timber harvest on private land occurred upstream of an
Oregon chub site on the William L. Finley National Wildlife Refuge
(Finley NWR) known as Gray Creek Swamp. Due to concerns about potential
sedimentation to Oregon chub habitat in Gray Creek Swamp, we negotiated
with the landowner who agreed to increase the width of the no-cut
riparian buffer along the streams within the harvest area to reduce the
risk of siltation in Oregon chub habitat downstream. Siltation of this
Oregon chub habitat following harvest has not been observed, but the
site will continue to be monitored by the ODFW during the 9-year post-
delisting monitoring period.
The potential for adverse effects to Oregon chub habitat from
timber harvest was also identified at three other sites: Dexter
Reservoir Alcove ``PIT1'' site, Buckhead Creek, and Wicopee Pond
(Scheerer 2008, pers. comm.). However, we did not observe levels of
siltation at
[[Page 9138]]
these sites that resulted in habitat loss, and all of the Oregon chub
populations within each of the five sites located downstream of harvest
activities met the delisting criteria in 2013. Additionally, the U.S.
Forest Service (USFS) manages several Oregon chub sites within the
Willamette National Forest. As noted above, forests managed by the USFS
operate under land and resource management plans that include
management practices protective of fish (USFS 1990, pp. IV-61-64), and
we anticipate these resource management plans will continue to guide
forest management into the future.
While future siltation of habitats occupied by Oregon chub from
timber harvest activities clearly is possible, the frequency is
anticipated to be very low, as will be the potential number of affected
populations. Given this fact, and the protections afforded by the
Oregon Forest Practices Act and Federal land management plans, we do
not believe siltation from timber harvest represents a substantial
population-level threat to Oregon chub now or in the foreseeable
future.
Floods and Seasonal High-Water Events
The Oregon chub is a low-elevation, floodplain-dependent species
that evolved under dynamic environmental conditions created by seasonal
flooding and droughts. As a result, the species' life history reflects
these dynamic conditions. While floods and seasonal high-water events
constitute a potential stressor to individuals or specific Oregon chub
populations, these events create and maintain off-channel habitats
necessary for the long-term persistence of the species, and they
function to transport the Oregon chub to colonize these new sites.
For example, in 2007, a flood event in the Santiam River caused
channel avulsion (a shift in the stream channel that results in the
rapid abandonment of a river channel and formation of a new river
channel) at an Oregon chub site, reducing the extent of habitat
available at this location and likely negatively affecting this
population. Yet in another example, between 2000 and 2003, new off-
channel habitat formed in the McKenzie River due to flooding and, after
aquatic vegetation became established, the site was subsequently
colonized by the Oregon chub (Bangs 2013, pers. comm.). Although we
cannot predict the magnitude or the extent to which current Oregon chub
habitats may be affected by flooding and seasonal high water events,
the number and distribution of large populations, in combination with
habitat heterogeneity, increases the species' resilience in recovering
from periodic disturbance, as the species would have historically.
Additional discussion about increased flood events is presented in the
``Effects of Climate Change'' section (also in Factor A).
Water Quality Issues
The analysis of threats in the final rule to list the Oregon chub
as an endangered species and the recovery plan for the species
discussed numerous potential threats to water quality in Oregon chub
habitats. However, in the 20 years since the Oregon chub was listed,
only a few of these concerns, discussed below, have materialized, and
even then, these were localized and of short duration.
In the spring of 2011, the ODFW noted the complete die-off of the
introduced Oregon chub population in Cheadle Pond on the Finley NWR.
They assessed the water quality (temperature, pH, and dissolved oxygen)
and discovered that the pH level was abnormally high (mean pH: 9.6,
range: 8.4-10.2). The pH level in Oregon chub habitats typically ranges
between 7.42 and 8.66. The cause of the increased pH level was unknown
and had not been observed previously at this site. The ODFW
subsequently conducted an in-situ 7-day bioassay using 30 adult Oregon
chub from the Gray Creek Swamp population. All of the Oregon chub
survived the trial and were released into Cheadle Pond following the
bioassay. We have not observed, and do not anticipate based on this one
event, similar incidents in other Oregon chub habitats.
Nutrient enrichment may have caused the extirpation of the Oregon
chub population at Oakridge Slough in the Middle Fork Willamette River
subbasin. The slough is downstream from the Oakridge Sewage Treatment
Plant, and increased nitrogen and phosphorus concentrations were
detected in the slough prior to a decline in the population. While the
nutrient concentrations are not believed to be directly harmful to the
species, the elevated nutrient levels may have contributed to habitat
conditions that were unsuitable for Oregon chub (i.e., an increase in
growth of algae, which then decomposed and led to low oxygen conditions
below what the Oregon chub requires to survive) (Buck 2003, p. 12).
Several Oregon chub sites are located adjacent to agricultural
land. Runoff from farm fields may contain pesticides or fertilizers
that could adversely affect the water quality in Oregon chub habitats.
However, many of these sites have protective vegetated buffers between
crops and the aquatic habitat. To date, we have not observed declines
in Oregon chub populations that can be attributed to agricultural
practices, and several Oregon chub habitats located adjacent to
farmland have supported abundant populations of Oregon chub for many
years.
Several Oregon chub sites are located adjacent to private
forestland (as previously discussed above under ``Siltation Resulting
from Timber Harvest''). Additionally, the USFS manages several Oregon
chub sites within the Willamette National Forest. Forests managed by
the USFS operate under land and resource management plans that include
management practices protective of fish (USFS 1990, pp. IV-61-64), and
we anticipate these resource management plans will continue to guide
forest management into the foreseeable future. On private forestland,
the use of chemicals is regulated by the Oregon Department of Forestry,
and operators are required to comply with product labels and additional
protective measures to protect waters of the State, including leaving
untreated vegetated buffers and limiting aerial applications near areas
of standing open water larger than one-quarter acre (Oregon Revised
Statutes (ORS) 527.765 and OAR 629-620-0000 through 629-620-0800).
Although we have no information regarding landowners' compliance with
these rules on forestland in the vicinity of Oregon chub habitats, we
have not observed harmful effects to Oregon chub populations due to
chemical exposure related to forestry operations.
During our analysis of the factors affecting the Oregon chub, we
determined that spills via sewage discharge, hazardous cargo from
trucks, railways and pipelines, which were identified as threats when
the species was first listed, no longer pose a significant threat to
the species. At the time of listing, of the nine Oregon chub
populations known to exist, seven of these locations were directly
adjacent to major transportation corridors where threats to water
quality had the potential to impact Oregon chub. Currently, Oregon chub
have been documented in 77 populations widely distributed throughout
the Willamette River Basin; 20 of these locations are adjacent to
transportation corridors. In addition, two populations are adjacent to
sewage treatment plants. Despite the proximity to potential threats to
water quality, in the 20 years since the Oregon chub was listed, only a
few of these concerns have materialized, and even then, these were
localized and of short duration. The current distribution of the Oregon
chub in many abundant
[[Page 9139]]
populations located across multiple subbasins reduces the risk that the
above factors will affect a large portion of Oregon chub and its
habitat. In summary, we conclude that none of the existing or potential
water quality-related threats, either alone or in combination with
others, constitutes a substantial threat to the Oregon chub now or in
the foreseeable future. Additional discussion about temperature and
dissolved oxygen levels is presented in the ``Effects of Climate
Change'' section (also in Factor A).
Aggradation
Aggradation is an alluvial process where sediment deposition
(deposition of all sizes of sediments, both coarse and fine) is more
rapid than the capacity of a river to transport sediment downstream. We
observed aggradation at the Geren Island North Channel in the North
Santiam River. Natural movement of the river channel changed sediment
deposition in the upstream end of this location, which had the
potential to block water flow into the site. The City of Salem, which
manages the site, excavated a portion of the channel to allow free-
flowing water to enter Oregon chub habitat. To date, we have not
observed a decline in the Geren Island population. With the exception
of this site and habitats in Fall Creek, which we discussed previously,
no other Oregon chub habitats are negatively impacted by aggradation.
We consider the potential negative impacts to the overall status of
Oregon chub from aggradation to be very low now and in the foreseeable
future.
Succession
Succession resulting from the manipulation of river flows was
identified as a potential threat to Oregon chub habitat in the
downlisting rule (75 FR 21179, April 23, 2010). Succession is a
natural, long-term ecological process that ponds go through as they
mature. As vegetation dies back seasonally, it deposits on the
substrate of the pond, causing a reduction in water depth over time.
Eventually, plant communities shift from aquatic to amphibious wetland
plants, and the open-water ponds are replaced by seasonal wetland and
marsh habitat. Historically, seasonal high flows and alluvial
floodplain processes created off-channel habitat, and rejuvenated
existing habitats by flushing out sediment and diversifying the aquatic
plant community. These processes no longer function as they did
historically because flows are regulated under the USACE's Willamette
Project. The Willamette Project dams were constructed in the 1940s
through the 1960s. Oregon chub populations have persisted under managed
flow conditions for more than 60 years. In addition, under the
Service's Willamette Project biological opinion (Service 2008b, pp. 40-
51) and the NMFS Willamette Project biological opinion (NMFS 2008, pp.
2-43 to 2-52), minimum flow levels established for listed salmonids
will continue to protect Oregon chub habitat. Other non-regulatory
efforts are working to restore floodplain function and sediment
transport, such as TNC's Willamette Sustainable Rivers Project. In this
project, TNC has developed an MOU with the USACE to release stored
water in high-flow pulses to restore natural processes in managed
portions of the Middle Fork, McKenzie, and Santiam Rivers. Given the
MOU between the USACE and TNC regarding the Sustainable Rivers Project,
and the minimum flows required under existing biological opinions from
the Service and NMFS, we anticipate flow management trending towards
natural flow regimes below Willamette Project dams will continue to
create and rejuvenate off-channel habitats and benefit Oregon chub into
the future.
We are not aware of any particular sites that are vulnerable to
succession in the near future; however, the sites that remain
hydrologically isolated during high flows are cut off from these
natural processes, and succession may continue resulting in a reduction
of open water habitat. For instance, succession occurred at Herman
Pond, an isolated Oregon chub site in the Coast Fork Willamette Basin,
which led to a reduction in habitat area and a decline in population
abundance. In 2005, the site was excavated to remove successional
vegetation. This activity was successful in increasing open water
habitat and led to an increase in Oregon chub abundance at this
location. Given the wide distribution and number of Oregon chub
habitats under different land ownership, we are uncertain whether
manual modification of chub habitats to reverse the effects of
succession will occur in the future following delisting. However, given
that we are not aware of any particular sites vulnerable to succession
in the foreseeable future, we determined that there is very little
potential negative impact, if any, to the overall status of Oregon chub
from succession.
Irrigation Withdrawals
A few Oregon chub sites may be influenced by irrigation water
withdrawals. In recent years, at Elijah Bristow Berry Slough in the
Middle Fork Willamette River subbasin, a drop in summer water level and
a significant decline in Oregon chub abundance coincided with increased
irrigation use by a farm located upstream. However, this was an
isolated event that we have not observed at other sites. Many Oregon
chub populations occur on publicly owned lands or on areas managed for
conservation, where direct water withdrawals do not occur. In addition,
water levels at habitats adjacent to mainstem river channels are highly
dependent on river flow, and are less likely to be negatively impacted
by irrigation withdrawals due to the amount of hyporheic (subsurface)
flow into these habitats from the adjacent river. Based on the wide
distribution of Oregon chub, we consider the potential negative impact
to the overall status of Oregon chub from irrigation withdrawals to be
very low.
Effects Related to Climate Change
Our analyses under the Act include consideration of observed or
likely environmental changes resulting from ongoing and projected
changes in climate. As defined by the Intergovernmental Panel on
Climate Change (IPCC), the term ``climate'' refers to the mean and
variability of different types of weather conditions over time, with 30
years being a typical period for such measurements, although shorter or
longer periods also may be used (IPCC 2013a, p. 1450). The term
``climate change'' thus refers to a change in the mean or the
variability of relevant properties, which persists for an extended
period, typically decades or longer, due to natural conditions (e.g.,
solar cycles) or human-caused changes in the composition of atmosphere
or in land use (IPCC 2013a, p. 1,450).
Scientific measurements spanning several decades demonstrate that
changes in climate are occurring. In particular, warming of the climate
system is unequivocal, and many of the observed changes in the last 60
years are unprecedented over decades to millennia (IPCC 2013b, p. 4).
The current rate of climate change may be as fast as any extended
warming period over the past 65 million years and is projected to
accelerate in the next 30 to 80 years (National Research Council 2013,
p. 5). Thus, rapid climate change is adding to other sources of
extinction pressures, such as land use and invasive species, which will
likely place extinction rates in this era among just a handful of the
severe biodiversity crises observed in Earth's geological record
(American Association for the Advancement of Sciences (AAAS) 2014, p.
17).
[[Page 9140]]
Examples of various other observed and projected changes in climate
and associated effects and risks, and the basis for them, are provided
for global and regional scales in recent reports issued by the IPCC
(2013c, 2014), and similar types of information for the United States
and regions within it can be found in the National Climate Assessment
(Melillo et al. 2014, entire).
Results of scientific analyses presented by the IPCC show that most
of the observed increase in global average temperature since the mid-
20th century cannot be explained by natural variability in climate and
is ``extremely likely'' (defined by the IPCC as 95 to 100 percent
likelihood) due to the observed increase in greenhouse gas (GHG)
concentrations in the atmosphere as a result of human activities,
particularly carbon dioxide emissions from fossil fuel use (IPCC 2013b,
p. 17 and related citations).
Scientists use a variety of climate models, which include
consideration of natural processes and variability, as well as various
scenarios of potential levels and timing of GHG emissions, to evaluate
the causes of changes already observed and to project future changes in
temperature and other climate conditions. Model results yield very
similar projections of average global warming until about 2030, and
thereafter the magnitude and rate of warming vary through the end of
the century depending on the assumptions about population levels,
emissions of GHGs, and other factors that influence climate change.
Thus, absent extremely rapid stabilization of GHGs at a global level,
there is strong scientific support for projections that warming will
continue through the 21st century, and that the magnitude and rate of
change will be influenced substantially by human actions regarding GHG
emissions (IPCC 2013b, 2014; entire).
Global climate projections are informative, and, in some cases, the
only or the best scientific information available for us to use.
However, projected changes in climate and related impacts can vary
substantially across and within different regions of the world (e.g.,
IPCC 2013c, 2014; entire) and within the United States (Melillo et al.
2014, entire). Therefore, we use ``downscaled'' projections when they
are available and have been developed through appropriate scientific
procedures, because such projections provide higher resolution
information that is more relevant to spatial scales used for analyses
of a given species (see Glick et al. 2011, pp. 58-61, for a discussion
of downscaling).
Various changes in climate may have direct or indirect effects on
species. These may be positive, neutral, or negative, and they may
change over time, depending on the species and other relevant
considerations, such as interactions of climate with other variables
such as habitat fragmentation (for examples, see Franco et al. 2006;
Forister et al. 2010; Galbraith et al. 2010; Chen et al. 2011). In
addition to considering individual species, scientists are evaluating
potential climate change-related impacts to, and responses of,
ecological systems, habitat conditions, and groups of species (e.g.,
Deutsch et al. 2008; Berg et al. 2010; Euskirchen et al. 2009;
McKechnie and Wolf 2010; Sinervo et al. 2010; Beaumont et al. 2011;
McKelvey et al. 2011; Rogers and Schindler 2011).
Climate change effects present substantial uncertainty regarding
the future environmental conditions in the Willamette River Basin and
may place an added stress on the Oregon chub and its habitats. The IPCC
has concluded that recent warming is already strongly affecting aquatic
biological systems, as evidenced by increased runoff and earlier spring
peak discharge in many glacier- and snow-fed rivers (IPCC 2007, p. 8).
Projections for climate change effects in North America include
decreased snowpack, more winter flooding, and reduced summer flows
(IPCC 2007, p. 14), which may increase periods of drought (Oregon
Climate Change Research Institute (OCCRI) 2010a, p. 112).
Observed changes in temperature in the Pacific Northwest (PNW)
already show an increase of 1.5 degrees Celsius over the past century
due to human activities (OCCRI 2010b, p. 6). Global climate models
project temperature increases for the PNW of approximately 2 to 4
degrees Celsius (3 to 10 degrees Fahrenheit) by 2080 (OCCRI 2010b, p.
7). Projections for climate change effects in the Willamette Valley in
the next century also include warmer air temperatures that will lead to
lower soil moisture and increased evaporation from streams and lakes
(Climate Leadership Initiative (CLI) and National Center for
Conservation Science and Policy (NCCSP) 2009, p. 9; OCCRI 2010a, p.
71). The frequency of short-term (3- and 6-month) droughts in the
Willamette Valley will likely increase due to decreased summer
rainfall, which may result in reduced summer baseflows and exacerbate
water temperature increases. However, long-term droughts (12 and 24
months) are not projected to substantially change across most of the
Willamette Basin (OCCRI 2010a, p. 112).
The 29,700-km\2\ (11,467-mi\2\) Willamette River Basin is a large
complex river basin, influenced by two mountain ranges: the Cascades
and the Coast Range (Chang and Jung 2010, pp. 187-190). The rain-
dominated Coast Range occupies about 20 percent of the basin; the
Cascade Range occupies more than 50 percent, and includes the rain-
dominated Western Cascades and the snow-dominated High Cascades. The
Willamette Valley region lies between these two ranges. Thus, the basin
has complex terrain and geology, and a wide range of elevations that
influence the timing and magnitude of runoff. Given this physical
variability, the effects of climate change will not uniformly affect
all areas or subbasins of the Willamette River (Chang and Jung 2010,
pp. 194-204).
The hydrology of the Willamette River Basin is largely influenced
by winter rainfall and spring snowmelt, with 77 percent of the flow
occurring between November and April (Chang and Jung 2010, p. 190).
Overall, the Willamette Basin is considered water abundant in Oregon.
In addition to rainfall, the basin is influenced by spring snowmelt and
spring-fed tributaries at higher elevations (e.g., High Cascades
region), and shallow groundwater aquifers in low-elevation areas in the
valley that recharge during the rainy season (OCCRI 2010a, p. 97-104).
The Willamette River and its tributaries are highly altered with
multiple large reservoirs and other human influences such as dams,
levees, and floodplain development. Multiple, large USACE dams,
constructed in the 1950s and 1960s for flood reduction, altered
seasonal discharge and temperatures, reduced peak flood flows, and
augmented summer low flows (OCCRI 2010a, p. 77). Climate change effects
that may affect Oregon chub include increased winter flooding,
increased temperatures, reduced summer baseflows, and increased
negative interactions with nonnative fishes. Each of these is discussed
below.
Increased Winter Floods--Effects of climate change predicted for
the PNW may include increased winter flood events (OCCRI 2010a, pp. 87-
88). These events, which are often associated with an increased
proportion of annual precipitation falling as rain instead of snow and
reduced snowpack, may better mimic natural riverine processes (such as
channel migration, scour, etc.) to create and maintain riverine
habitats on which Oregon chub depend. Oregon chub evolved in a dynamic,
alluvial river with broad floodplains and braided reaches with many
side channels, sloughs, and other similar slack-water habitats. Large
floods
[[Page 9141]]
commonly rearranged these side-channel habitats, creating new habitats
in some locations, and filling in other areas. The construction and
operation of the USACE's Willamette Project, a system of 13 flood
control dams, has reduced flooding and associated habitat forming
processes in the Willamette River Basin, thereby simplifying mid- to
low-elevation, aquatic habitats considerably. During previous flood
events, the Willamette Project dams have been able to capture and
reduce the magnitude of the flow to keep flood waters from impacting
downstream communities; the magnitude of these flows were still high
enough to alter the stream and floodplain habitat. Increased flows
associated with climate change may contribute to the creation and
maintenance of off-channel floodplain habitats upon which Oregon chub
depend (e.g., side channels, oxbows, etc.), thereby increasing the
amount of suitable habitat for the species. For these reasons, it is
possible that increases in winter floods associated with climate change
may benefit Oregon chub through the creation and maintenance of their
habitats.
Temperature and Dissolved Oxygen Effects--The Oregon chub is
tolerant of a wide range of temperatures and thus less vulnerable to
temperature effects of climate change than other listed fish species in
the Willamette River Basin (e.g., bull trout, spring chinook salmon,
and winter steelhead). Oregon chub do not require cool temperatures for
spawning or other life-history needs and appear tolerant of low
dissolved oxygen (DO) levels. DO levels and temperature are related
because at higher temperatures, water has a reduced ability to store
oxygen. While the upper lethal temperature limit of Oregon chub has not
been determined, the best available data based on field observations
suggest this limit is approximately 31 to 35 degrees Celsius (88 to 95
degrees Fahrenheit) for adult Oregon chub, and that tolerance may be
associated with low DO levels (Scheerer and Apke 1997, p. 25; Bangs et
al. 2009, p. 17). Temperature and DO tolerances for juvenile Oregon
chub appear to be higher than that of adults (Scheerer and Apke 1997,
p. 25; Bangs et al. 2009, p. 17). The observed maximum summer
temperature range of occupied Oregon chub habitat is from 23 to 39
degrees Celsius (73 to 102 degrees Fahrenheit) (Bangs 2014, pers.
comm.). Despite a proportion of these habitats experience temperatures
in excess of 35 degrees Celsius (95 degrees Fahrenheit) (which may
result in the loss of some individuals within that population), an
entire population has not been lost due to temperature increases and
associated low DO levels.
While global climate models project a temperature increase for the
PNW of approximately 2 to 4 degrees Celsius (3.6 to 7.2 degrees
Fahrenheit) by 2080 (OCCRI 2010b, p. 7), climate models primarily
predict air temperature changes, which have led many to believe that
water temperatures will also correspondingly rise (Arismendi et al.
2012, p. 1). However, water temperatures did not follow expected
warming trends or experience the same magnitude of increased
temperature as air temperature when analyzing stream temperature data
from the Pacific continental United States (Arismendi et al. 2012, p.
4). In many cases, water temperatures were found to have more cooling
trends than warming trends since 1987, and less variability, especially
in highly human-influenced rivers (Arismendi et al. 2012, pp. 4-5).
Such is the case in the Willamette River; the presence of the 13 USACE
flood control dams in the Willamette Valley allows for some
amelioration of extreme climate variation, such as temperature extremes
and drought. These large dams may be able to adaptively operate in the
future to partially offset some of the potential increases in water
temperature and flow reductions below the dams, if determined
appropriate.
Releases of water below the USACE's Willamette Project dams
generally target water temperatures ranging from 12 to 18 degrees
Celsius (54 to 64 degrees Fahrenheit), depending on the season. These
releases decrease downstream summer river temperatures by 6 to 10
degrees Celsius (10.8 to 18 degrees Fahrenheit) from historic
temperatures (Rounds 2010, p. 43) and augment summer low flows (OCCRI
2010a, p. 77). The USACE is working to better mimic historical
temperature conditions through water releases at several dams, which
primarily target temperature benefits to federally listed salmonids
that remain protected under the Act. These salmonid species require
much cooler waters than Oregon chub. For example, juvenile salmonids
generally prefer temperatures from 11.7 to 14.7 degrees Celsius (53.1
to 58.5 degrees Fahrenheit), and spawning temperatures for these
species are typically below 13.0 degrees Celsius (55.4 degrees
Fahrenheit) (Richter and Kolmes 2005, pp. 27-28). The needs of these
listed salmonids will continue to influence future management
decisions. Thus, dam releases targeting these cooler temperature
requirements will be protective of Oregon chub habitats downstream of
these dams.
Potential reductions in summer baseflows may increase water
temperatures (OCCRI 2010a, p. 114). Increased frequency of short-term
droughts (3 to 6 months) may reduce the USACE's ability to meet all of
the minimum instream flow volumes, especially during late summer and
early fall. Many populations (40 out of 77 populations, and 10 of the
23 populations that meet recovery criteria) exist in riverine habitats
influenced by releases from the USACE's dams.
While increased frequency of short-term drought may reduce the
USACE's ability to meet required instream flows for listed salmonids,
we do not anticipate these reductions will result in temperature
increases that constitute a substantial threat to Oregon chub now or
into the foreseeable future. These dams currently maintain cooler
summer temperatures and higher summer baseflows below the dams than
existed prior to dam construction, and thereby provide a buffer from
increased temperatures. Further, the USACE is required to coordinate
with the Service, ODFW, and NMFS when minimum instream flows cannot be
met, which allows the Service to weigh in on the magnitude of
reductions and mitigate negative effects to Oregon chub populations if
necessary. For these reasons, we determine potential instream flow
reductions, and any associated temperature increases and reduced DO
levels due to increased short-term droughts do not constitute a
substantial threat to Oregon chub in habitats below the dams.
Other populations exist outside the influence of the dam releases.
Eighteen populations exist in ``up-slope'' habitats that are not
directly influenced rivers (6 of these populations met all recovery
criteria in 2013); 14 populations occur on or adjacent to undammed
rivers (3 met recovery criteria); 5 are adjacent to USACE reservoirs (4
met recovery criteria). The potential effects to each of these habitat
categories are discussed below.
The 18 ``upslope'' populations were introductions into isolated
ponds, as discussed above. Predicted reductions in summer rainfall and
increased evaporation may reduce the volume or depth of these ponds in
late summer, increase water temperature, and correspondingly decrease
DO levels in these habitats. However, these introduction sites were
selected because the habitat is expected to remain stable during
extreme climatic events such as droughts or floods. Each of these
habitats was chosen for its ability to remain wetted during drought and
provide a diversity of habitats
[[Page 9142]]
throughout a range of pool elevations. For example, some sites rely on
ground water springs or modern water control structures to maintain
pond elevations throughout summer.
While it is possible that climate change may impact some aquatic
habitats to the extent they no longer can support Oregon chub, the
probability of that occurring is low given the wide tolerances of this
species to water temperatures and corresponding DO levels. The
diversity of isolated Oregon chub habitats spread across multiple
watersheds provides further buffers against population level impacts
from climate change. For these reasons, we determine that temperature
effects due to climate change to these ``up-slope'' habitats do not
constitute a substantial threat to Oregon chub now or into the
foreseeable future.
Fourteen Oregon chub populations occur on or adjacent to undammed
rivers: 13 of these populations are naturally occurring and on or
adjacent to rain-dominated, undammed tributaries to the Willamette
River (e.g., Marys, Molalla, and Luckiamute Rivers, and Muddy Creek);
and 1 population occurs in a spring-fed pond upstream of a USACE dam
and thus is unlikely to experience substantial temperature increases or
other negative impacts from climate change. For the 13 populations,
potential reductions in summer baseflows and associated increases in
water temperature are the most likely negative impacts to these
populations from climate change effects (including short-term
droughts). However, uncertainty in the extent and magnitude of summer
baseflow reductions remains high despite modeling efforts (Chang and
Jung 2010, pp. 198-202; see following discussion). Given this
uncertainty regarding summer baseflow reductions, we cannot predict to
what level summer baseflows may drop (and thereby increase water
temperatures) and negatively impact these habitats.
We anticipate few of these habitats will be negatively affected to
such an extent Oregon chub cannot exist given the high tolerance of
Oregon chub to temperature and associated reduced DO levels, the fact
that ground water connections to these habitats may remain, and these
habitats are distributed across several watersheds with differing
influences (Chang and Jung 2010, p. 204). For these reasons, we
determine that temperature effects due to climate change in these rain-
dominated, undammed tributary habitats do not constitute a substantial
threat to Oregon chub now or into the foreseeable future.
The remaining five populations occupy habitats adjacent to USACE
reservoirs in the Middle Fork Willamette River: Two populations at
Lookout Point Reservoir, two at Dexter Reservoir, and one at Fall Creek
Reservoir. Reductions in snow, increases in rain, increased frequency
of short-term droughts, instream flow requirements, and related
increased water demand for agricultural and municipal uses during
droughts may put additional stresses on water supply in the Willamette
Basin. These stresses may reduce the USACE's ability to maintain
reservoir levels year-round, especially during the late summer and
early fall. These reservoir-associated populations are most likely to
experience temperature increases, reduced DO levels, and reduction in
habitat from loss of connection with the reservoirs, which may occur in
the future during predicted short-term droughts. However, we have
direct experience with this situation: in 2010, the USACE drew these
reservoirs down through the summer of 2011 for dam-safety repairs.
The ODFW monitored these populations closely during and after
reservoirs returned to normal levels (Bangs et al. 2012, p. 18). No
populations were lost due to these reduced reservoir levels, despite
reduced habitat and high summer temperatures. While some populations
experienced a decline the following year, one population increased.
Those populations that experienced a decline due to lowered reservoir
levels recovered to previous abundance levels (Bangs et al. 2012, p.
10).
In summary, the Oregon chub is tolerant of a wide range of
temperatures and not dependent on cool waters to complete its life
history. Oregon chub populations are dispersed across a wide range of
diverse habitats, each influenced by site specific factors. The
predicted increases in water temperature and associated reductions in
DO levels from climate change effects are not anticipated to exceed the
tolerances for Oregon chub throughout its range. Also, coordination
between the Service and the USACE is required when minimum instream
flow requirements will not be met. For these reasons, we determine that
temperature increases associated with climate change effects are not a
threat to Oregon chub across its range.
Oregon chub are tolerant of a wide range of temperatures and
associated decreases in DO, and are thus less vulnerable to temperature
effects of climate change than other listed fish species in the
Willamette Valley. Information specific to Oregon chub regarding its
ability to make behavioral or physiological responses to temperature
changes is not available. However, given their observed temperature
tolerance (up to 31 to 35 degrees Celsius, 88 to 95 degrees Fahrenheit)
relative to potential climate increases in water temperature, the
coordination of instream flows and reservoir management with the USACE,
and the multiple populations across a range of ecological settings and
tributaries in the Willamette Basin, we conclude that temperature
effects from climate change do not constitute a substantial threat to
Oregon chub now, or in the foreseeable future.
Reduction in Summer Baseflows--Climate change effects with the most
potential to negatively affect Oregon chub are reduced summer
baseflows, which may reduce habitat availability within existing
habitats and exacerbate increases in water temperature and declines in
DO. Chang and Jung (2010, entire) examined future runoff projections in
the Willamette River Basin under eight global climate models and two
emissions scenarios. Some consistent trends exist between different
models with regards to summer flow conditions: the 7-day low flow
minimum decreased in most subbasins of the Willamette River Basin, and
the Western Cascade basins (medium elevation) showed greater declines
than those in the Willamette Valley (low elevation) and the High
Cascades (high elevation) (Chang and Jung 2010, pp. 198-202). However,
the range of predicted changes was much more variable in the Willamette
Valley and Western Cascades where the majority of Oregon chub
populations exist. Further, the predicted changes for both summer
runoff and the 7-day low flow minimum were very different depending on
the emissions scenario used in the model, and the predicted changes
varied by subbasin (Chang and Jung 2010, pp. 201-202).
Given the uncertainty in climate change predictions with differing
models and future emission scenarios, we cannot specify the amount of
reductions in summer baseflows for each subbasin and extrapolate how
those reductions will affect habitat availability, temperatures, and DO
(alone or in concert) in individual Oregon chub habitats. Such fine-
scale models are not available. Despite modeled projections of changes
in temperature, precipitation, and runoff at the global, regional, and
basin scale, we cannot: (1) Predict with any certainty how those
changes may influence Oregon chub populations and their
[[Page 9143]]
individual habitats in the Willamette Valley; and (2) accurately
describe and assess the net effects when considering the potential
negative consequences together with the potential positive effects to
Oregon chub populations.
Oregon chub habitats are often located in side-channel and off-
channel areas that are highly influenced by site-specific conditions,
including, but not limited to factors such as above- and below-ground
water connections between the habitat and the river system or aquifer,
and total volume and depth of the habitat. For example, lower baseflows
that seasonally disconnect above-ground flow to a side-channel habitat
may or may not result in reduced habitat availability and increased
temperatures, depending on whether cooler, below-ground water
connection to the side channel is maintained.
Oregon chub habitats exist throughout the Willamette River Basin in
a variety of subbasins at a variety of elevations, with varying geology
and topography, and with differing climatic influences. Modeling
conducted by Chang and Jung (2010, pp. 198-204) suggests that the
interactions between climate change and land surface hydrology are
complex. Because of these varying factors, each subbasin will respond
differently to the effects of climate change. Thus, not all Oregon chub
populations in the Willamette River Basin will be similarly affected by
climate change effects. Because of the variety of habitats within a
single subbasin, it is unlikely that all habitats within a single
subbasin will experience negative effects to the extent that habitat no
longer supports Oregon chub. Further, potential reductions in summer
baseflows in portions of the Willamette Basin will likely be moderated
by the continuing operations of the USACE's large storage dams that
capture a portion of the flood flows from winter and spring
precipitation events (including snowmelt) and gradually release these
flows over the summer. Thus, for many existing Oregon chub populations,
we do not anticipate substantial reductions in summer baseflows. If
such reductions are necessary, our coordination with the USACE, as
described earlier in this document, will allow the Service to minimize
and mitigate impacts to Oregon chub.
For Oregon chub habitats outside of the influence of USACE dam
releases, insufficient information exists to determine the magnitude of
future reductions in summer baseflows and associated changes in
temperature and DO levels. Substantial reductions, if they occur, may
result in the reduction of available habitat or in some instances the
loss of individual populations. However, we do not anticipate such
negative effects across the range of Oregon chub. Based on the existing
information collected on Oregon chub since its listing, we anticipate
Oregon chub will continue to exist because of its demonstrated
resiliency in the past in the face of continual change: Oregon chub
have survived despite significant landscape changes across the
Willamette River Basin, including the effects of many dams and
floodplain development. Studies to date have shown this species is
highly adaptable, and able to quickly colonize new habitats. The
effects of climate change will continue to progress into the future
gradually. We anticipate that not all Oregon chub populations as they
exist today will still exist 40 to 50 years from now, but that Oregon
chub will exist in abundant and stable populations throughout the
Willamette River Basin, colonizing new side channels and habitats as
hydrology and floodplains adjust to a changed climate. Thus, we
determine that reductions in summer baseflows and any associated
increases in temperatures and declines in DO levels do not constitute a
substantial threat to Oregon chub now, nor will they be in the
foreseeable future.
Competition and Predation by Nonnative Fish Species--Climate change
effects may locally alter Oregon chub habitats to the advantage of
nonnative species known to compete with and prey on Oregon chub via
increasing water temperature and reducing connectivity to river systems
during low flow conditions (e.g., summer baseflows). However, the best
available data show no relationship between the presence of nonnative
fish and Oregon chub population abundance trends (Bangs et al. 2013, p.
17). Thirteen of the 23 populations that met delisting criteria with
either a stable or increasing abundance trend in 2013 occur with
nonnative fish; 1 of the 2 populations that had a declining abundance
trend occurs with nonnative fish (Bangs et al. 2013, p. 17). The
primary driver affecting the abundance and dominance of nonnative fish
in suitable Oregon chub habitats appears to be connectivity of these
off-channel habitats to the larger river system. To date, these
nonnative competitors and predators have not completely overtaken
suitable Oregon chub habitats that remain seasonally connected to these
river systems because annual flood flows disrupt and flush the
nonnative species out of these suitable habitats, whereas Oregon chub
have developed behaviors that allow them to remain as they evolved with
these high flows. In summary, we do not anticipate climate change
effects on the abundance and distribution of nonnative fish in the
Willamette Basin will increase competition and predation. We determine
that this competition and predation does not constitute a substantial
threat to Oregon chub now, nor will they be in the foreseeable future.
Summary for Climate Change Effects--The Willamette River Basin is a
geologically complex system, as well as a highly altered and managed
system with multiple large reservoirs and other human influences.
Although effects of climate change are almost certain to impact aquatic
habitats in the Willamette River Basin (CLI and NCCSP 2009, p. 1),
researchers have great uncertainty about the specific effects of
climate change, including which models and emission scenarios are the
best representation of the future. Thus, despite modeled projections of
changes in temperature, precipitation, and runoff, we cannot: (1)
Predict with any certainty how those changes may influence individual
Oregon chub populations and their habitats in the Willamette Basin; and
(2) accurately describe and assess the net effects when considering the
potential negative consequences together with the potential positive
effects to Oregon chub populations.
The effects of climate change have potentially both positive and
negative impacts to Oregon chub habitats; there is a wide diversity of
habitats occupied by Oregon chub that are individually influenced by
the site-specific factors and suitable habitats for Oregon chub are
found throughout the Willamette Basin. Oregon chub as a species has
proven itself highly adaptable and resilient to change. We cannot
project with any certainty whether the effects of climate change will
provide more benefits or threats to Oregon chub. However, the best
available information suggests that Oregon chub and their habitats are
not highly vulnerable to the potential effects of climate change across
their range and we do not anticipate that climate change will have
population level effects to Oregon chub.
The Service developed a strategic plan to address the threat of
climate change to vulnerable species and ecosystems. Goals of this plan
include maintaining ecosystem integrity by protecting and restoring key
ecological processes such as nutrient cycling, natural disturbance
cycles, and predator-prey relationships (Service 2010, p. 23). The
Oregon chub recovery
[[Page 9144]]
program worked to establish conditions that allow populations of Oregon
chub to be resilient to changing environmental conditions and to
persist as viable populations into the future. Our recovery program for
the species focused on maintaining large populations distributed within
the species' entire historical range in a variety of ecological
settings (e.g., across a range of elevations). This approach is
consistent with the general principles of conservation biology. In
their review of minimum population viability literature, Traill et al.
(2009, p. 3) found that maintenance of large populations across a range
of ecological settings increases the likelihood of species persistence
under the pressures of environmental variation, and facilitates the
retention of important adaptive traits through the maintenance of
genetic diversity. Maintaining multiple populations across a range of
ecological settings, as described in the recovery plan, increases the
likelihood that many abundant populations will persist under the
stresses of a changing climate.
Summary of Factor A
Many of the factors discussed above were previously identified as
threats to the continued existence of the Oregon chub. These factors
include activities associated with the operation of the Willamette
Project dams, sedimentation from timber harvest, floods or high-water
events, water quality-related impacts, succession, and the effects of
climate change. Modifications to the Willamette Project dam operations
have provided flows that create and sustain off-channel habitat used by
the Oregon chub, and we anticipate these flow targets will continue
into the future due to requirements under biological opinions from the
Service and NMFS, and the Sustainable Rivers Project collaboration
between the USACE and TNC. Sedimentation from timber harvest is not
currently indicated in the decline of any Oregon chub populations, and
we expect that riparian buffers protected from timber harvest under
State and Federal regulations will provide habitat protection in future
timber harvest operations. Flooding and high-water events are largely
unpredictable. However, Oregon chub evolved within a dynamic
environment and the current distribution of Oregon chub in many
abundant populations within subbasins and across multiple subbasins
reduces the risk that these events will negatively affect a large
proportion of Oregon chub and its habitat. Declines in water quality
related to factors such as chemical contamination, nutrient enrichment,
siltation, and hazardous material spills have the potential to affect
individual populations, but few observations of negative effects due to
water quality issues have materialized over the past 20 years that we
have been monitoring Oregon chub populations. Succession was a factor
at one Oregon chub site and may occur in the future, particularly at
sites that are isolated from the floodplain. However, succession is a
slow process that can be addressed through ongoing monitoring and
habitat management, and is not currently a cause for concern at any of
the known Oregon chub sites.
Other factors that may affect the Oregon chub and its habitat
include actions required under the terms and conditions of the
Willamette Project biological opinions, aggradation, and irrigation
withdrawals. Actions required under the Willamette Project biological
opinions began in 2008, but the effects to Oregon chub habitat from
these actions are not well understood as the focus of most of these
actions is recovery of listed salmonids. Research into the effects of
these actions on off-channel habitats started in 2009 and will continue
for the next few years. This research may lead to an improved
understanding of the habitat characteristics that support abundant
populations of Oregon chub in connected habitats and flow management
recommendations specific to maintaining Oregon chub habitat.
Aggradation from natural causes has been identified at one Oregon chub
site, and aggradation from a complete drawdown of Fall Creek Reservoir
resulted in large deposits of sediment in three previously unknown
Oregon chub habitats. Other than these events, aggradation has not been
observed at Oregon chub sites. Irrigation withdrawal was observed to
negatively affect the volume of water available in one Oregon chub
habitat in the Middle Fork River subbasin, but is not considered a
widespread concern throughout the range of Oregon chub.
In summary, the factors discussed under Factor A continue to occur
across the subbasins occupied by Oregon chub, but only a few
populations have exhibited declines as a result of any of the factors
or combination of factors. The threat of habitat loss has been reduced
by changes in flow management and by introducing the species into
secure, isolated habitats that are not influenced by floodplain
processes. We also better understand the diversity of connected
habitats used by Oregon chub and, as a result, discovered many abundant
populations in these habitats across multiple subbasins. Therefore,
based on the best available information and because we expect that
current management practices will continue into the foreseeable future,
we conclude that the present or threatened destruction, modification,
or curtailment of its habitat or range does not constitute a
substantial threat to Oregon chub now and is not expected to in the
foreseeable future.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Overutilization for commercial, recreational, scientific, or
educational purposes was not a factor in listing, nor is it currently
known to be a threat to the Oregon chub.
C. Disease or Predation
Predation by Nonnative Fishes and Amphibians
In the final rule to downlist the Oregon chub (75 FR 21179, April
23, 2010), we identified predation by, and competition with, nonnative
fishes as primary threats to Oregon chub (competition with nonnative
fishes is addressed below under Factor E). The Willamette River Basin
contains 31 native fish species and 29 nonnative species (Hulse et al.
2002, p. 44). The large-scale alteration of the Willamette River
Basin's hydrologic system (i.e., construction of dams and the resultant
changes in flood frequency and intensity) created conditions that favor
nonnative, predatory fishes, and reservoirs throughout the basin have
become sources of continual nonnative fish invasions in the reaches
downstream (Li et al. 1987, p. 198). Significant declines in Oregon
chub abundance due to the presence of nonnative fishes were documented.
For instance, after floods in 1996, nonnative fish were first collected
from several sites containing Oregon chub in the Santiam River
drainage; the two largest populations of Oregon chub (Geren Island
North Pond and Santiam Easement) subsequently declined sharply in
abundance (Scheerer 2002, p. 1076).
Nonnative fish, which prey upon Oregon chub, were also introduced
into Oregon chub habitats. For example, illegal planting of largemouth
bass at East Ferrin Pond in the Middle Fork Willamette River drainage
coincided with the collapse of an Oregon chub population that had once
totaled more than 7,000 fish. A regulatory mechanism is in place to
prevent the translocation of nonnative fish. Within the State of
Oregon, it is unlawful to transport, release, or attempt to release any
live
[[Page 9145]]
fish into the waters of this State (OAR 635-007-0600). Although similar
illegal introductions may still occur in the future, they have
historically been infrequent in habitats known to be occupied by Oregon
chub.
Predatory, nonnative centrarchids (bass and sunfish), western
mosquitofish (Gambusia affinis), and bullhead catfish (Ameiurus spp.)
are common in the off-channel habitats preferred by Oregon chub
(Scheerer 2002, p. 1,075). The Oregon chub is most abundant at sites
where nonnative fishes are absent (Scheerer 2007, p. 96). However, ODFW
biologists recently found many abundant Oregon chub populations that
coexist with nonnative fish in hydrologically connected habitats (Bangs
et al. 2011a, pp. 21-24). One of the primary objectives of the
floodplain study funded under the Willamette Project biological opinion
(Service 2008b, pp. 180-182; see previous discussion under Factor A) is
to examine the relationship between the environmental conditions at
hydrologically connected sites and the fish community, with a focus on
Oregon chub and nonnative fish. The results to date indicate that
spatial and seasonal differences in temperature within these off-
channel habitats may provide areas that are suitable for Oregon chub
but not suitable for nonnatives. In other words, Oregon chub may be
able to coexist with nonnative fish because the habitat provides a
diverse range of temperatures that partitions habitats among the
species (Bangs et al. 2011a, pp. 9-10 and 16-17). Currently, 41 percent
of all known Oregon chub habitats and 50 percent of the habitats
supporting abundant populations (more than 500 Oregon chub) contain
nonnative fishes. Research conducted under the study will continue to:
(1) Improve our understanding of the effects of nonnative fishes on
Oregon chub in these connected habitats; and (2) document the habitat
conditions that allow these species to coexist. Sampling results to
date indicate that Oregon chub coexist with nonnatives more frequently
than previously known. Additional discussion about predation by
nonnative fish is presented in the ``Effects of Climate Change''
section (discussed under Factor A).
Bullfrogs (Rana catesbeiana) were identified as a threat to Oregon
chub in the recovery plan (Service 1998, p. 13) because they may
compete with Oregon chub for food resources (e.g., invertebrates).
However, bullfrogs are prevalent in most of the habitats occupied by
Oregon chub and their presence is not correlated with a decline in
Oregon chub abundance (Bangs 2013, pers. comm.).
The Oregon chub is not known to be threatened by disease.
Summary of Factor C
Although the habitat conditions that allow Oregon chub to coexist
with nonnative fish are not yet well understood, we documented several
abundant Oregon chub populations in multiple subbasins that coexist
with nonnative, predatory fish. These Oregon chub populations exist in
habitat that is connected to the active floodplain. Ongoing research
conducted under the floodplain study funded by the USACE will continue
to improve our understanding of the interactions between Oregon chub
and nonnative fishes.
While the presence of nonnative fishes in isolated sites may be
associated with higher rates of predation on Oregon chub, the species
has been introduced into 21 isolated habitats that are protected from
the risk of invasion by nonnative fishes due to the habitat distance
from the floodplain or other fish barriers. As discussed elsewhere in
this document, these introductions act as refugial habitats, and the
guidelines used to select sites ensure that these locations remain
stable during extreme climactic events, such as droughts or floods.
During major flooding in the Willamette River Basin in 1996, these
sites remained isolated from neighboring water bodies. In addition, the
introduction sites are less vulnerable to the threats of habitat loss
compared to connected habitats, and the translocation guidelines
ensured that the Oregon chub in these isolated populations are
genetically diverse. Introduced populations at these sites have been
highly successful, and the majority of Oregon chub individuals occur in
populations at these sites. Therefore, based on the best available
information, we conclude that disease and predation do not constitute
substantial threats to Oregon chub now, nor are they expected to in the
foreseeable future.
D. The Inadequacy of Existing Regulatory Mechanisms
In evaluating the inadequacy of existing regulatory mechanisms, we
first identify threats under one or more of the other four factors that
are affecting the species to the extent it meets the definition of an
endangered or a threatened species under the Act. We then identify and
evaluate the adequacy of existing regulatory mechanisms that may
prevent or reduce those threats. The Oregon chub, however, is no longer
facing substantial threats to its long-term survival due to the other
four factors; thus the inadequacy of existing regulatory mechanisms is
also no longer a threat to the species' continued existence. Therefore,
our discussion of this factor focuses on regulatory mechanisms not
previously discussed that may provide benefits to Oregon chub.
Wetlands and waterways in Oregon are protected by both Federal and
State laws. The Environmental Protection Agency (EPA) administrates the
Clean Water Act (CWA; 33 U.S.C. 1251 et seq.)), which regulates
discharges of pollutants into waters of the United States and regulates
water quality standards. The EPA sets standards for pollution control
programs and water quality standards for all contaminants in surface
waters. Many of the water quality criteria are set for human health
standards or salmon and steelhead life stage needs, which exceed
biological requirements for Oregon chub. For example, the upper
temperature tolerance of Oregon chub is significantly higher than the
maximum allowable temperatures set by EPA criteria for salmon and
steelhead spawning and rearing.
While we acknowledge that there are Oregon chub in reaches in the
Willamette River that are on the section 303(d) list of impaired and
threatened waters under the CWA, Oregon chub populations have continued
to expand throughout the Willamette River Basin in spite of these
section 303(d) waters. Further, we do not foresee future water quality
declines (i.e., temperature, dissolved oxygen, biological criteria)
that are a threat to the continued existence of Oregon chub and require
its continued listing under the Act. The Service has consulted with the
EPA on existing Oregon water quality standards and the Service's
biological opinion concluded that the Oregon water quality standards
are not likely to jeopardize the continued existence of Oregon chub
(Service 2004, pp. 76-77). While the courts remanded the 2004
biological opinion back to the Service, and we continue to work with
the EPA to complete this consultation, the remand was based on thermal
requirements for bull trout, not Oregon chub.
Under section 404 of the CWA, the USACE regulates the discharge of
dredged material and fill material into waters of the United States,
including navigable waters and wetlands that may contain Oregon chub.
Oregon's Removal-Fill Law (ORS 196.795-990) requires people who plan to
remove or fill material in waters of the State to obtain a permit from
the Oregon
[[Page 9146]]
Department of State Lands (DSL). Projects impacting waters often
require both a State removal-fill permit, issued by the DSL, and a
Federal permit issued by the USACE. A permit is required only if 50
cubic yards (1,350 cubic feet) or more of fill or removal will occur.
The removal-fill law does not regulate the draining of wetlands.
Projects permitted under these programs must avoid and minimize impacts
to wetlands or waterways, or propose mitigation to replace the
functions and values lost as a result of the project (Oregon Department
of State Lands 2013, p. 64). Some actions, however, such as
construction and maintenance of irrigation-diversion structures and
other activities associated with ongoing farming operations in existing
cropped wetlands, are exempt from CWA requirements. Additionally,
projects authorized under a nationwide USACE permit program receive
minimal public and agency review unless the action may affect a listed
species, in which case, consultation under section 7 of the Act is
required. Individual permits are subject to a more rigorous review, as
well as nationwide permit activities with more than minimal impacts.
Under section 303(c) of the CWA, States are required to adopt water
quality standards to restore and maintain the chemical, physical, and
biological integrity of the nation's waters. Oregon adopted revised
water quality standards for toxic pollutants in 2004. These standards
are intended to protect native aquatic species, and are regulated by
the Oregon Department of Environmental Quality. The State implements
the standards through listing of waters that exceed criteria on the
section 303(d) list of the CWA, calculating the Total Maximum Daily
Loads (the maximum amount of pollutants that may enter a stream), and
issuing or reissuing permits (i.e., National Pollutant Discharge
Elimination System). In 2012, we completed consultation under section 7
of the Act on the EPA's proposed approval of the State of Oregon's
water quality criteria for toxic pollutants (Service 2012, entire).
Although some Oregon chub sites may be affected by point-source
discharges (i.e., wastewater treatment facilities and stormwater
discharge from a manufacturing plant) and non-point-source discharges
(i.e., runoff of agricultural and forestry pesticides and fertilizers)
of toxic chemicals, we determined in our consultation with the EPA that
the Oregon chub's exposure to these chemicals at the criteria levels
and the resulting effects would not jeopardize the species' continued
existence, adversely modify or destroy Oregon chub critical habitat, or
reach levels preventing Oregon chub from attaining the abundance and
distribution criteria for delisting identified in the recovery plan
(Service 2012, pp. 351-352).
The Oregon chub is designated as ``Sensitive-Critical'' by the
ODFW. Although this designation is a nonregulatory tool, it helps focus
wildlife management and research activities, with the goal of
preventing species from declining to the point of qualifying as
``threatened'' or ``endangered'' under the Oregon Endangered Species
Act (ORS 496.171, 496.172, 496.176, 496.182, and 496.192). ODFW's
``Sensitive-Critical'' designation encourages, but does not require,
the implementation of conservation actions for the species; however,
other State agencies, such as the DSL and the Oregon Water Resources
Department, refer to the Sensitive Species List when making regulatory
decisions.
The ODFW's Sensitive Species List is reviewed and updated every 5
years. Each taxonomic group of animals is reviewed by the ODFW
biologists and scientific experts from other agencies, universities,
and private organizations. The scientists consider new and historic
information on species distribution, population trends, and biological
needs; changes in threats; gaps in knowledge and data; recent
conservation actions; and State and Federal programs or regulations.
The scientists may propose to remove, add, or re-classify species based
on this information. The draft list is then peer-reviewed by State,
Federal, university, and consulting biologists. The ODFW is currently
updating the Sensitive Species List and plans to retain the
``Sensitive-Critical'' designation for Oregon chub for the duration of
the post-delisting monitoring plan timeframe.
Summary of Factor D
Although existing regulatory mechanisms offer limited protection to
Oregon chub, we have no indication that other factors, which these
mechanisms are designed to address, are likely to occur at such a
magnitude as to negatively impact large numbers of Oregon chub or a
substantial area of habitat. Therefore, based on the best available
information, we conclude that the inadequacy of existing regulatory
mechanisms does not constitute a substantial threat to Oregon chub now,
nor is it projected to in the future.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
Interspecific Competition With Nonnative Fishes
Along with the adverse impacts of direct predation described under
Factor C (above), nonnative fishes compete with Oregon chub for food
resources, such as aquatic invertebrates. Competition with nonnative
fishes may contribute to the decline in populations or exclusion of
Oregon chub from suitable habitats. Observed feeding strategies and
diet of nonnative fishes, particularly juvenile centrarchids and adult
western mosquitofish, overlap with those described for Oregon chub (Li
et al. 1987, pp. 197-198). At South Stayton Pond, a hydrologically
isolated site in the Santiam River Basin, we observed a population of
6,200 Oregon chub decline to 2,200 in one season after invasion by
western mosquitofish, a nonnative fish that competes with adults and
potentially predates on larval Oregon chub. The source of this invasion
is unknown, but it is likely that the western mosquitofish were
illegally introduced into the pond. The population remained above 1,000
for the past 4 years (Bangs 2014, pers. comm.), demonstrating the
ability of nonnative fish to competitively suppress Oregon chub
populations. Other populations of the Oregon chub are possibly
suppressed by competition with nonnative fishes. However, the current
abundance of Oregon chub and its distribution throughout floodplain
habitats in the Santiam, McKenzie, and Middle Fork Willamette Rivers
indicates that competition by nonnative fish is not affecting Oregon
chub populations to the degree that overall status declines are
observed. Additional discussion about competition by nonnative fish is
presented in the ``Effects of Climate Change'' section (see Factor A).
Isolated Populations
Twenty-eight populations of the Oregon chub are currently isolated;
21 of these sites are introduced sites where isolation was intentional
in order to provide refugia from the threat of nonnative fishes. Other
sites are isolated due to the reduced frequency and magnitude of flood
events and the presence of migration barriers such as beaver dams.
Managing species in isolation may have genetic consequences. Burkey
(1989, p. 78) 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.
[[Page 9147]]
Without sufficient immigration, growth of local populations may be low
and probability of extinction high (Burkey 1989, p. 78). The genetic
analyses performed on Oregon chub (DeHaan et al. 2010, pp. 14-19; 2012,
pp. 548-549) found high levels of genetic variation at most locations.
Also, the genetic analyses found that our guidelines for establishing
introduction sites are effective, and introductions stocked from
multiple donor sources have higher variability than those from single
donor sources. In addition, 50 of the 77 Oregon chub populations are
located in habitat that experiences some level of connectivity to the
adjacent river channel; 34 of these populations were discovered since
we downlisted the Oregon chub to threatened status in 2010.
Furthermore, the ODFW documented Oregon chub in new habitat created by
floodplain processes in the McKenzie River subbasin, and documented
voluntary movement of Oregon chub between populations in the Middle
Fork Willamette River (Bangs et al. 2012, p. 19) and McKenzie River
subbasins (Bangs et al. 2013, p. 17). These findings demonstrate the
ability of Oregon chub to colonize new habitats and exchange genetic
material between established populations. Manual transport of Oregon
chub between populations has not been proposed, and we think it
unnecessary at this time for the maintenance of populations. Although a
recent genetic analysis found that Oregon chub in isolated habitats
have levels of genetic diversity equal to or greater than other
cyprinids, additional Oregon chub may need to be introduced into these
isolated populations in the future to maintain genetic diversity in the
event a population shows a significant decline.
In the final rule to reclassify Oregon chub to threatened (75 FR
21179, April 23, 2010), we expressed concern about genetic isolation
due to the lack of habitat connectivity between Oregon chub
populations. As stated above, we discovered that many of the habitats
occupied by the Oregon chub connect to the adjacent river channel more
frequently and for longer duration than previously understood, which
provides opportunities for genetic dispersal.
Summary of Factor E
Interspecific competition with nonnative fishes and isolation from
genetic exchange may affect Oregon chub populations in the future.
However, we observed population declines related to competition with
nonnative fishes in only one Oregon chub population, South Stayton
Pond, a small habitat area with limited resources. Although this
decline was substantial (abundance of 6,200 chub declined to 2,200 chub
in one season), the population since stabilized and persists with about
1,000 Oregon chub (Bangs et al. 2013, p. 6). We documented numerous
additional abundant Oregon chub populations in habitats that are
connected to the floodplain, which facilitates potential genetic
exchange among populations. This has ameliorated the risk of a
reduction in genetic diversity. The impacts associated with the effects
of climate change will be somewhat ameliorated by the multiple storage
dams in the Willamette River Basin, the wide range of temperature
tolerances of Oregon chub, and the diversity of habitats occupied by
the species. To the extent the effects of climate change manifest on
the landscape, these impacts are, and will continue to be, reduced by
the distribution of many abundant populations in diverse habitats
across multiple subbasins. Therefore, based on the best available
information, we conclude that other natural or manmade factors do not
constitute a substantial threat to Oregon chub now, nor will they in
the foreseeable future.
Cumulative Impacts
Some of the factors discussed in this five-factor analysis could
work in concert with one another or synergistically to create
cumulative impacts to Oregon chub populations. For example, effects
from flow, dam operations, and temperature changes downstream of
Willamette Project dams may coincide with an increase in nonnative fish
species that prey upon and compete with Oregon chub. Although the
types, magnitude, extent, or permutations of cumulative impacts are
difficult to assess, the current status of Oregon chub indicates that
no such synergies drive population declines now or have the potential
to in the future, and the post-delisting monitoring plan is designed to
detect such declines if they occur. As discussed below, the agencies
and nongovernmental organizations that manage multiple populations
agreed to cooperate on the implementation of the post-delisting
monitoring plan, which will guide the monitoring and, should population
declines occur, necessary research and conservation actions. The best
scientific and commercial data available indicate that Oregon chub is
genetically diverse, abundant, and well-distributed throughout its
historical range and that the factors are not currently, or anticipated
to, cumulatively cause declines in Oregon chub populations or its
habitat.
Overall Summary of Factors Affecting Oregon Chub
The primary factors that threatened Oregon chub were loss of
habitat, predation and competition by nonnative fishes, and the
inadequacy of existing regulatory mechanisms. The threats that led to
the species' listing under the Act have been removed or ameliorated by
the actions of multiple conservation partners over the last 20 years.
The introduction of Oregon chub into several secure habitats has
provided populations that are isolated from the threats of habitat loss
and invasion by nonnative fishes. The discovery of many natural
populations, including a number of populations that are connected to
the active floodplain and coexist with nonnative fishes, has increased
our understanding of population persistence in spite of the presence of
predators in the species' environment. The implementation of minimum
instream flows and ongoing flushing flows from Willamette Project dams
that sustain floodplain habitat downstream reduced the risk of habitat
loss due to altered flows. The acquisition of floodplain habitat for
long-term conservation and restoration provided assurance that
management of floodplain habitat for the species will continue into the
foreseeable future.
Many factors still exist that may affect Oregon chub populations;
however, most of these factors were isolated incidents, and the
magnitude of their effects were not observed on a wide scale across the
distribution of Oregon chub populations. The abundance and distribution
of known Oregon chub populations has increased each year since the
downlisting to threatened, and has exceeded the goals of our recovery
criteria for delisting. When the species was listed in 1993, only nine
populations of Oregon chub within a small, restricted range were known
to occur. Oregon chub populations now exist in 77 diverse habitats
across multiple subbasins. Listing the species under the Act resulted
in the implementation of focused recovery actions that led to
protected, abundant, and well-distributed Oregon chub populations
across several Willamette River Basin tributaries. We expect
conservation efforts will continue to support persistent recovered
Oregon chub populations post-delisting and into the future, as
described above. Based on this assessment of factors potentially
impacting the species, we consider Oregon chub to face no
[[Page 9148]]
substantial threats, now or into the foreseeable future.
Determination
An assessment of the need for a species' protection under the Act
is based on whether a species is in danger of extinction or likely to
become so because of any of five factors: (A) The present or threatened
destruction, modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) the inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. As required by section 4(a)(1) of
the Act, we conducted a review of the status of this species and
assessed the five factors to evaluate whether the Oregon chub is
endangered or threatened throughout all of its range. We examined the
best scientific and commercial information available regarding the
past, present, and future threats faced by Oregon chub and its habitat.
We reviewed the information available in our files and other available
published and unpublished information, and we consulted with recognized
experts and other Federal, State, and Tribal agencies.
In considering what factors might constitute threats, we must look
beyond the mere exposure of the species to the factor to determine
whether the exposure causes actual impacts to the species. If there is
exposure to a factor, but no response, or only a positive response,
that factor is not a threat. If there is exposure and the species
responds negatively, the factor may be a threat and we then attempt to
determine how significant the threat is. If the threat is significant,
it may drive, or contribute to, the risk of extinction of the species
such that the species warrants listing as endangered or threatened as
those terms are defined by the Act. This determination does not
necessarily require empirical proof of a threat. The combination of
exposure and some corroborating evidence of how the species is likely
impacted could suffice. The mere identification of factors that could
impact a species negatively is not sufficient to compel a finding that
listing is appropriate; we require evidence that these factors are
operative threats that act on the species to the point that the species
meets the definition of an endangered species or threatened species
under the Act.
We find that Oregon chub populations are well-distributed among
several subbasins and that many large, stable, or increasing
populations exist that show no evidence of decline over the last 7 or
more years. During our analysis, we did not identify any factors that
are likely to reach a magnitude that threatens the continued existence
of the species; significant impacts at the time of listing that could
have resulted in the extirpation of all or parts of populations have
been eliminated or reduced since listing, and we do not expect any of
these conditions to substantially change post-delisting and into the
foreseeable future. We conclude that the previously recognized impacts
to Oregon chub from the present or threatened destruction,
modification, or curtailment of its habitat or range (specifically,
operation of the USACE's Willamette Project dams, sedimentation from
timber harvest and floods, water quality issues, succession, and
effects of climate change (Factor A); predation by nonnative species
(Factor C); and interspecific competition with nonnative species, and
isolation from genetic exchange (Factor E)), do not rise to a level of
significance such that the species is in danger of extinction
throughout all of its range now or in the foreseeable future.
Significant Portion of the Range Analysis
Having determined that the Oregon chub throughout all its range, is
not endangered or threatened throughout all of its range, we next
consider whether there are any significant portions of its range in
which the Oregon chub is in danger of extinction or likely to become
so. Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
throughout all or a significant portion of its range. The Act defines
``endangered species'' as any species which is ``in danger of
extinction throughout all or a significant portion of its range,'' and
``threatened species'' as any species which is ``likely to become an
endangered species within the foreseeable future throughout all or a
significant portion of its range.'' We published a final policy
interpreting the phrase ``Significant Portion of its Range'' (SPR) (79
FR 37578; July 1, 2014). The final policy states that (1) if a species
is found to be endangered or threatened throughout a significant
portion of its range, the entire species is listed as endangered or
threatened, respectively, and the Act's protections apply to all
individuals of the species wherever found; (2) a portion of the range
of a species is ``significant'' if the species is not currently
endangered or threatened throughout all of its range, but the portion's
contribution to the viability of the species is so important that,
without the members in that portion, the species would be in danger of
extinction, or likely to become so in the foreseeable future,
throughout all of its range; (3) the range of a species is considered
to be the general geographical area within which that species can be
found at the time the Service or NMFS makes any particular status
determination; and (4) if a vertebrate species is endangered or
threatened throughout an SPR, and the population in that significant
portion is a valid Distinct Population Segment (DPS), we will list the
DPS rather than the entire taxonomic species or subspecies.
The procedure for analyzing whether any portion is an SPR is
similar, regardless of the type of status determination we are making.
The first step in our analysis of the status of a species is to
determine its status throughout all of its range. If we determine that
the species is in danger of extinction, or likely to become so in the
foreseeable future, throughout all of its range, we list the species as
an endangered species (or threatened species) and no SPR analysis will
be required. If the species is neither in danger of extinction nor
likely to become so throughout all of its range, we next determine
whether the species is in danger of extinction or likely to become so
throughout a significant portion of its range. If it is, we list the
species as an endangered species or threatened species, respectively;
if it is not, we conclude that listing the species is not warranted.
When we conduct an SPR analysis, we first identify any portions of
the species' range that warrant further consideration. The range of a
species can theoretically be divided into portions in an infinite
number of ways. However, there is no purpose in analyzing portions of
the range that have no reasonable potential to be significant or in
analyzing portions of the range in which there is no reasonable
potential for the species to be endangered or threatened. To identify
only those portions that warrant further consideration, we determine
whether substantial information indicates that: (1) The portions may be
``significant'' and (2) the species may be in danger of extinction
there or likely to become so within the foreseeable future. Depending
on the biology of the species, its range, and the threats it faces, it
might be more efficient for us to address the significance question
first or the status question first. Thus, if we determine that a
portion of the range is not ``significant,'' we do not need to
determine whether the species is
[[Page 9149]]
endangered or threatened there; if we determine that the species is not
endangered or threatened in a portion of its range, we do not need to
determine if that portion is ``significant.'' In practice, a key part
of the determination that a species is in danger of extinction in a
significant portion of its range is whether the threats are
geographically concentrated in some way. If the threats to the species
are affecting it uniformly throughout its range, no portion is likely
to have a greater risk of extinction, and thus would not warrant
further consideration. Moreover, if any concentration of threats apply
only to portions of the range that clearly do not meet the biologically
based definition of ``significant'' (i.e., the loss of that portion
clearly would not be expected to increase the vulnerability to
extinction of the entire species), those portions would not warrant
further consideration.
We considered whether any portions of Oregon chub range might be
both significant and in danger of extinction, or likely to become so in
the foreseeable future. One way to identify portions would be to
identify natural divisions within the range that might be of biological
or conservation importance. The geographic range of Oregon chub can
readily be divided into four subbasins (Santiam, Mainstem Willamette,
Middle Fork Willamette, and Coast Fork Willamette Rivers). Although
some of the factors we evaluated in the Summary of Factors Affecting
the Species section, above, occur in specific habitat types (i.e.,
hydrologically connected sites versus isolated sites) within these
subbasins, the factors affecting Oregon chub generally occur at
similarly low levels throughout its range. Because the low level of
potential threats to the species is essentially uniform throughout its
range and the populations of the species within the subbasins are not
in danger of extinction or likely to become so within the foreseeable
future due to lack of significant threats, no portion of the range
warrants further consideration to determine if it is significant. Based
on our review of the best available information concerning the
distribution of the species and the potential threats, we have
determined that the Oregon chub does not warrant further consideration
to determine if there is a significant portion of the range that is
endangered or threatened.
Summary
We carefully assessed the best scientific and commercial data
available and determined that the Oregon chub is no longer in danger of
extinction throughout all or a significant portion of its range, nor is
it likely to become so within the foreseeable future. We conclude
Oregon chub no longer requires the protection of the Act, and,
therefore, we are removing it from the Federal List of Endangered and
Threatened Wildlife.
Future Conservation Measures
Section 4(g)(1) of the Act requires us, in cooperation with the
States, to implement a monitoring program for not less than 5 years for
all species that have been recovered and delisted. The purpose of this
post-delisting monitoring (PDM) is to verify that a species remains
secure from risk of extinction after the protections of the Act are
removed, by developing a program that detects the failure of any
delisted species to sustain itself. If, at any time during the
monitoring period, data indicate that protective status under the Act
should be reinstated, we can initiate listing procedures, including, if
appropriate, emergency listing under section 4(b)(7) of the Act.
Post-Delisting Monitoring Plan Overview
The Service developed a final PDM plan in cooperation with the
ODFW. In addition, the USACE, USFS, Oregon Parks and Recreation
Department, McKenzie River Trust, and Willamette Valley National
Wildlife Refuge Complex agreed to cooperate with us in the
implementation of the PDM plan. The PDM plan is designed to verify that
the Oregon chub remains secure from the risk of extinction after
removal from the Federal List of Endangered and Threatened Wildlife by
detecting changes in its status and habitat throughout its known range.
The final PDM plan consists of: (1) A summary of the species' status at
the time of delisting; (2) an outline of the roles of PDM cooperators;
(3) a description of monitoring methods; (4) an outline of the
frequency and duration of monitoring; (5) an outline of data
compilation and reporting procedures; and (6) a definition of
thresholds or triggers for potential monitoring outcomes and
conclusions of the PDM effort.
The final PDM plan will monitor Oregon chub populations following
the same sampling protocol used by the ODFW prior to delisting.
Monitoring will consist of three components: Oregon chub distribution
and abundance, potential adverse changes to Oregon chub habitat due to
environmental or anthropogenic factors, and the distribution of
nonnative fishes in Oregon chub habitats. The PDM period consists of
three 3-year cycles (9 years total), which will begin in 2015. Both
Willamette Project biological opinions continue until 2023, and flow
and temperature augmentation will be implemented during this period
(Service 2008b, pp. 68-72; NMFS 2008, pp. 2-43 to 2-52, 2-125 to 2-
128). Monitoring through this time period will allow us to address any
possible negative effects to Oregon chub associated with changes to
flow and temperatures. As funding allows, we will collect data on
roughly three generations of Oregon chub in each of the three
subbasins, which will allow time to observe fluctuations in population
abundance that may be attributed to residual stressors. Sites included
in the floodplain study will be sampled annually over the next 9 years,
enabling the Service and PDM partners to recommend flow and temperature
regimes that are beneficial to native fishes in to the future. Sites
outside the floodplain study will be sampled only once during each 3-
year cycle, thus reducing annual sampling costs from current levels.
The final PDM plan identifies measurable management thresholds and
responses for detecting and reacting to significant changes in Oregon
chub protected habitat, distribution, and persistence. If monitoring
detects declines equaling or exceeding these thresholds, the Service in
combination with other PDM participants will investigate causes of
these declines, including considerations of habitat changes,
substantial human persecution, stochastic events, or any other
significant evidence. Such investigation will determine if Oregon chub
warrants expanded monitoring, additional research, additional habitat
protection, or relisting as an endangered or a threatened species under
the Act. If relisting Oregon chub is warranted, emergency procedures to
relist the species may be followed, if necessary, in accordance with
section 4(b)(7) of the Act.
We will post the final PDM plan and any future revisions on our
national Web site (http://endangered.fws.gov) and on the Oregon Fish
and Wildlife Office's Web site (http://www.fws.gov/oregonfwo/).
Effects of the Rule
This final rule revises 50 CFR 17.11(h) by removing Oregon chub
from the Federal List of Endangered and Threatened Wildlife. As such,
as of the effective date of this rule (see DATES), the prohibitions and
conservation measures provided by the Act, particularly through
sections 7 and 9, no longer apply to this species (including
[[Page 9150]]
those contained in the existing conservation agreement, all safe harbor
agreements, and all biological opinions for this species). There are no
habitat conservation plans related to Oregon chub. Removal of Oregon
chub from the Federal List of Endangered and Threatened Wildlife
relieves Federal agencies from the need to consult with us under
section 7 of the Act to ensure that any action they authorize, fund, or
carry out is not likely to jeopardize the continued existence of this
species. This final rule also revises 50 CFR 17.95(e) by removing the
designated critical habitat for Oregon chub throughout its range.
Required Determinations
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)
This rule does not contain any new collections of information that
require approval by the Office of Management and Budget (OMB) under the
Paperwork Reduction Act. This rule will not impose recordkeeping or
reporting requirements on State or local governments, individuals,
businesses, or organizations. An agency may not conduct or sponsor, and
a person is not required to respond to, a collection of information
unless it displays a currently valid OMB control number.
National Environmental Policy Act
We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), need not be
prepared in connection with regulations pursuant to section 4(a) of the
Act. We published a notice outlining our reasons for this determination
in the Federal Register on October 25, 1983 (48 FR 49244).
References Cited
A complete list of all references cited in this final rule is
available at http://www.regulations.gov at Docket No. FWS-R1-ES-2014-
0002, or upon request from the Oregon Fish and Wildlife Office (see
ADDRESSES).
Authors
The primary authors of this rule are staff members of the Service's
Oregon Fish and Wildlife Office with assistance from ODFW staff (see
ADDRESSES and FOR FURTHER INFORMATION CONTACT).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as follows:
PART 17--[AMENDED]
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless
otherwise noted.
Sec. 17.11 [Amended]
0
2. Amend Sec. 17.11(h) by removing the entry for ``Chub, Oregon''
under FISHES in the List of Endangered and Threatened Wildlife.
Sec. 17.95 [Amended]
0
3. Amend Sec. 17.95(e) by removing the entry for ``Oregon Chub
(Oregonichthys crameri)''.
Dated: December 16, 2014.
Stephen Guertin,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2015-02951 Filed 2-18-15; 8:45 am]
BILLING CODE 4310-55-P