Rule2025-22335
Endangered and Threatened Wildlife and Plants; Notice of 12-Month Finding on a Petition To List the Oregon Coast and Southern Oregon and Northern California Coastal Chinook Salmon Evolutionarily Significant Units Under the Endangered Species Act
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
December 9, 2025
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
We, NMFS, have completed a comprehensive status review of the Oregon Coast (OC) and Southern Oregon and Northern California Coastal (SONCC) Chinook salmon (Oncorhynchus tshawytscha) Evolutionarily Significant Units (ESUs) in response to a petition to list these species as threatened or endangered under the Endangered Species Act (ESA) and to designate critical habitat concurrently with the listings. Based on the best scientific and commercial information available, including the status review report, and taking into account efforts being made to protect the species, we have determined that the OC and SONCC Chinook salmon ESUs do not warrant listing.
Full Text
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<title>Federal Register, Volume 90 Issue 234 (Tuesday, December 9, 2025)</title>
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[Federal Register Volume 90, Number 234 (Tuesday, December 9, 2025)]
[Rules and Regulations]
[Pages 56993-57011]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-22335]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Parts 223 and 224
[Docket No. 251204-0176: RTID 0648-XR123]
Endangered and Threatened Wildlife and Plants; Notice of 12-Month
Finding on a Petition To List the Oregon Coast and Southern Oregon and
Northern California Coastal Chinook Salmon Evolutionarily Significant
Units Under the Endangered Species Act
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, NMFS, have completed a comprehensive status review of the
Oregon Coast (OC) and Southern Oregon and Northern California Coastal
(SONCC) Chinook salmon (Oncorhynchus tshawytscha) Evolutionarily
Significant Units (ESUs) in response to a petition to list these
species as threatened or endangered under the Endangered Species Act
(ESA) and to designate critical habitat concurrently with the listings.
Based on the best scientific and commercial information available,
including the status review report, and taking into account efforts
being made to protect the species, we have determined that the OC and
SONCC Chinook salmon ESUs do not warrant listing.
DATES: This finding was made available on December 9, 2025.
ADDRESSES: The petition, status review report, Federal Register
notices, and the list of references can be accessed electronically
online at: <a href="https://www.fisheries.noaa.gov/species/Chinook-salmon-protected#conservation-management">https://www.fisheries.noaa.gov/species/Chinook-salmon-protected#conservation-management</a>. The peer review report is available
online at: https://www.noaa.gov/
[[Page 56994]]
information-technology/biological-status-of-oregon-coast-and-southern-
oregon-northern-california-coastal-Chinook-salmon.
FOR FURTHER INFORMATION CONTACT: Robert Markle, NMFS West Coast Region,
at <a href="/cdn-cgi/l/email-protection#592b363b3c2b2d7734382b32353c1937363838773e362f"><span class="__cf_email__" data-cfemail="d1a3beb3b4a3a5ffbcb0a3babdb491bfbeb0b0ffb6bea7">[email protected]</span></a>, (971) 710-8155; or Heather Austin, NMFS
Office of Protected Resources, at <a href="/cdn-cgi/l/email-protection#50383531243835227e31252324393e103e3f31317e373f26"><span class="__cf_email__" data-cfemail="92faf7f3e6faf7e0bcf3e7e1e6fbfcd2fcfdf3f3bcf5fde4">[email protected]</span></a>, (301) 427-
8422.
SUPPLEMENTARY INFORMATION:
Background
On August 4, 2022, we received a petition from the Native Fish
Society, Center for Biological Diversity, and Umpqua Watersheds to list
the OC and SONCC Chinook salmon ESUs as threatened or endangered under
the ESA or, alternatively, list only spring-run Chinook salmon in both
the OC and SONCC ESUs as threatened or endangered under the ESA. On
January 11, 2023, we published a 90-day finding (88 FR 1548) announcing
that the petition presented substantial scientific and commercial
information indicating the petitioned actions to list the OC and SONCC
Chinook salmon ESUs may be warranted. With respect to the request to
list only the spring-run components of those ESUs, we found that the
petition did not present substantial scientific and commercial
information indicating that the petitioned action was warranted. We
also initiated a status review of the species, as required by section
4(b)(3)(A) of the ESA, and requested information to inform the agency's
decision on whether the species warrant listing as threatened or
endangered under the ESA. We received information from the public in
response to the 90-day finding and incorporated that information into
both the status review report and this 12-month finding. This
information complemented our thorough review of the best available
scientific and commercial data for these species (see Status Review
below).
Listing Determinations Under the ESA
We are responsible for determining whether a species meets the
definition of threatened or endangered under the ESA (16 U.S.C. 1531 et
seq.). To make this determination, we first consider whether a group of
organisms constitutes a species under section 3 of the ESA, then
whether the status of the species qualifies it for listing as either
threatened or endangered. Section 3 of the ESA defines ``species'' to
include ``any subspecies of fish or wildlife or plants, and any
distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature'' (16 U.S.C. 1532(16)). In 1991,
we issued the Policy on Applying the Definition of Species Under the
Endangered Species Act to Pacific Salmon (ESU Policy; 56 FR 58612,
November 20, 1991). Under the ESU Policy, a Pacific salmon population
is a distinct population segment (DPS), and hence a species under the
ESA, if it represents an ESU of the biological species. The ESU Policy
identifies two criteria for making ESU determinations: (1) it must be
substantially reproductively isolated from other conspecific population
units and (2) it must represent an important component in the
evolutionary legacy of the species. The first criterion, reproductive
isolation, need not be absolute, but must be strong enough to permit
evolutionarily important differences to accrue in different population
units. A population would meet the second criterion if it contributes
substantially to the ecological and genetic diversity of the species as
a whole.
We use the ESU Policy exclusively for delineating distinct
population segments of Pacific salmon. A joint NMFS--U.S. Fish and
Wildlife Service (USFWS) (jointly, the Services) policy clarifies the
Services' interpretation of the phrase ``distinct population segment''
for the purposes of listing, delisting, and reclassifying a species
under the ESA (DPS Policy; 61 FR 4722, February 7, 1996). In announcing
this policy, the Services indicated that the ESU Policy was consistent
with the DPS Policy and that NMFS would continue to use the ESU Policy
for Pacific salmon.
Section 3 of the ESA further defines an endangered species as ``any
species which is in danger of extinction throughout all or a
significant portion of its range'' and a threatened species as one
``which is likely to become an endangered species within the
foreseeable future throughout all or a significant portion of its
range'' (16 U.S.C. 1532(6), (20)). Thus, we interpret an ``endangered
species'' to be one that is presently in danger of extinction. A
``threatened species,'' on the other hand, is not presently in danger
of extinction, but is likely to become so in the foreseeable future.
When we consider whether a species qualifies as threatened under
the ESA, we must consider the meaning of the term ``foreseeable
future.'' 50 CFR 424.11(d) provides: ``In determining whether a species
is a threatened species, the Services must analyze whether the species
is likely to become an endangered species within the foreseeable
future. The foreseeable future extends as far into the future as the
Services can make reasonably reliable predictions about the threats to
the species and the species' responses to those threats. The Services
will describe the foreseeable future on a case-by-case basis, using the
best available data and taking into account considerations such as the
species' life-history characteristics, threat-projection timeframes,
and environmental variability. The Services need not identify the
foreseeable future in terms of a specific period of time.''
Section 4(a)(1) of the ESA requires us to determine whether any
species is endangered or threatened as a result of any one or a
combination of the following 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 (16 U.S.C. 1533(a)(1)). Section
4(b)(1)(A) of the ESA requires us to make listing determinations solely
on the basis of the best scientific and commercial data available after
conducting a review of the status of the species and after taking into
account efforts, if any, being made by any state or foreign nation or
political subdivision thereof to protect the species. In evaluating the
efficacy of existing domestic conservation efforts, we rely on the
Services' joint Policy for Evaluation of Conservation Efforts When
Making Listing Decisions (PECE; 68 FR 15100, March 28, 2003) for any
conservation efforts that have yet to be implemented or demonstrate
effectiveness.
Life History of Chinook Salmon
The largest of the Pacific salmon, Chinook salmon (Oncorhynchus
tshawytscha) are in the Salmonidae subfamily, which consists of six
genera of trout and salmon (Nelson et al. 2016). Chinook salmon are
anadromous and semelparous (i.e., individuals die after spawning).
Their life history involves incubation, hatching, and emergence in
freshwater, migration to the ocean, and subsequent return to freshwater
for completion of maturation and spawning. Within this general life
history strategy, however, Chinook salmon display considerable
variation with respect to age at outmigration from freshwater, ocean
distribution and migratory patterns, length of residence in the ocean,
and time of year in which they return to freshwater and spawn. Juvenile
rearing in freshwater can be
[[Page 56995]]
minimal or extended; the majority (~95 percent) of Chinook salmon in
the OC and SONCC ESUs typically migrate to the ocean in their first
year of life (ODFW 2007a, ODFW 2013, ODFW 2014a). This is sometimes
referred to as an ocean-type life history as opposed to fish that
overwinter and migrate to the ocean as yearlings (stream-type life
history).
Duration of ocean residence is highly variable. Some Chinook salmon
rear in the ocean for less than 1 year, returning to freshwater as age-
2 fish and are almost all males (known as ``jacks''). The most common
life history is 2 or 3 years of ocean residence and sexual maturation
at age 3 or 4 (ODFW 2007a, 2013, 2014a). A smaller proportion of fish
rear in the ocean for 4 years and return to freshwater as age-5 fish,
while an even small percentage rear in the ocean for 5 years and return
at age 6.
Chinook salmon may return to their natal river mouth during almost
any month of the year (Healey 1991). Temporal ``runs'' of Chinook
salmon are identified by the time of year in which adult salmon return
to freshwater to spawn. Although the timing of the run is the focus,
distinct runs also differ in the degree of maturation at the time of
river entry and actual time of spawning (Myers et al. 1998). For
example, spring-run Chinook salmon tend to enter freshwater as immature
or ``bright'' fish, migrate farther upriver, and finally spawn in the
late summer and early autumn. In contrast, fall-run Chinook salmon
generally enter freshwater at a more advanced stage of maturity, move
rapidly to their spawning areas on the mainstem or lower tributaries of
the rivers, and spawn within a few days or weeks of freshwater entry
(Myers et al. 1998).
Previous ESA Status Reviews
OC Chinook Salmon ESU
In 1998, we conducted a comprehensive status review of West Coast
Chinook salmon populations in California, Oregon, Washington, and Idaho
(Myers et al. 1998). We convened an expert panel of scientists from
NMFS' Northwest and Southwest Fisheries Science Centers, NMFS'
Northwest and Southwest Regional Offices, and a representative of the
National Biological Survey to (1) identify ESUs of West Coast Chinook
salmon and (2) evaluate their risk of extinction. During this review,
we determined that the OC Chinook salmon ESU is composed of coastal
populations of fall- and spring-run Chinook salmon from the Elk River
north to the mouth of the Columbia River.
This ESU falls within the Coastal Ecoregion which has a strong
maritime influence, with moderate temperatures and high precipitation
levels. Regional rainfall averages 200-240 cm per year, with generally
lower levels to the south of this ESU. Average annual river flows for
most rivers in this region are among the highest found on the West
Coast when adjusted for watershed area. These conditions allow
returning adult fish easy access to the river systems' upper reaches.
Populations within this ESU typically migrate to the ocean in their
first year of life (ocean-type), spend most of their marine life in
coastal waters, and mature at ages 3, 4, and 5. This ESU contains
several large estuary areas: Tillamook Bay, Coos Bay, Winchester Bay,
and Yaquina Bay. Sub-yearling Chinook salmon in these systems utilize
productive estuary areas as rearing habitat before they emigrate to the
ocean.
In contrast to the more southerly ocean distribution pattern shown
by populations from the lower Columbia River and from populations south
of this ESU, populations within the OC Chinook salmon ESU have a
predominantly northerly coastal distribution as evidenced from coded-
wire-tag recoveries from British Columbia and Alaska coastal fisheries.
Myers et al. (1998) also identified a strong genetic separation between
Oregon Coast ESU populations and neighboring populations to the north
and south. Based on the available information, we concluded that OC
Chinook salmon met the ESU criteria because they were (1) substantially
reproductively isolated from populations of Chinook salmon to the north
and south and (2) represented an important component in the
evolutionary legacy of the species.
Myers et al. (1998) concluded that production in this ESU was
mostly dependent on naturally-spawning fish, and spring-run Chinook
salmon in this ESU were in relatively better condition than those in
adjacent ESUs. Long-term trends in abundance of Chinook salmon within
most populations in this ESU were upward (1950-1997).
In spite of a generally positive outlook for this ESU, Myers et al.
(1998) noted that several populations were exhibiting severe (greater
than 9 percent per year) short-term declines in abundance (1987-1996).
In addition, there were several hatchery programs releasing Chinook
salmon throughout the ESU, and many of the fish were from a single
stock (Trask River). Most importantly, there was a lack of clear
information on the degree of straying among these hatchery fish into
naturally-spawning populations. There were also many populations within
the ESU for which there were no abundance data and NMFS was concerned
about the uncertain risk assessment given these data gaps. Finally,
NMFS was concerned that harvest could be a significant source of risk
if exploitation rates were to revert back to historically high rates.
Also, freshwater habitats were generally in poor condition, with
numerous problems such as low summer flows, high temperatures, loss of
riparian cover, and streambed changes (Myers et al. 1998).
Previous assessments of stocks within the OC ESU identified several
stocks at risk or of concern. Of the eight (out of 22 total stocks)
within this ESU considered by Nehlsen et al. (1991), they identified
two stocks at high extinction risk (South Umpqua River and Coquille
River spring-run), one stock at moderate extinction risk (Yachats River
fall-run) and five stocks of ``special concern.'' Nehlsen et al. (1991)
defined a population as ``special concern'' if it met certain criteria
that did not yet put it in a high or moderate risk category but still
warranted attention. Of the 44 stocks within this ESU considered by
Nickelson et al. (1992), they identified 26 as healthy, 2 as depressed
(South Umpqua River and Coquille River spring-run Chinook salmon), 7 as
of ``special concern'' due to hatchery strays, and 9 of unknown status
(4 of which they suggested may not be viable). Of the 18 stocks
evaluated in Huntington et al. (1996), 6 were identified as healthy
Level I (those having adult abundance at least two-thirds as great as
would be found in the absence of human impacts) and 12 healthy Level II
stocks (those with adult abundance between one-third and two-thirds as
great as expected without human impacts).
In 1998, this ESU had relatively high abundance and occupied most
of the available habitat. Production in this ESU was mostly dependent
on naturally-spawning fish. Long-term trends in abundance of Chinook
salmon within most populations in this ESU were upward. Informed by the
findings in the 1998 status review of West Coast Chinook salmon, we
previously concluded that the OC Chinook salmon ESU did not warrant
listing under the ESA (63 FR 11482; March 9, 1998).
SONCC Chinook Salmon ESU
Based on the results of the status report on West Coast Chinook
salmon (Myers et al. 1998), we originally identified a Southern Oregon
and California Coastal Chinook salmon ESU and proposed to list it as
threatened (63
[[Page 56996]]
FR 11482, March 9, 1998). After completing an updated status review
(NMFS 1999), we determined that the best available information
supported dividing the previously identified ESU into two ESUs: a SONCC
Chinook salmon ESU and a California Coastal Chinook salmon ESU. A
summary of the updated status review findings for the SONCC Chinook
salmon ESU follows.
In 1999, we completed an analysis of new genetic data collected
from spawned adult Chinook salmon in 1998 and 1999 (West Coast Chinook
Salmon Biological Review Team 1999). We analyzed the new samples along
with data for California and southern Oregon Chinook salmon used in the
NMFS coastwide status review (Myers et al. 1998). The new analysis
revealed two genetic groups composed of samples from the Klamath River
Basin and from coastal rivers. Within the Klamath River Basin, the Blue
Creek population in the lower Klamath River was more similar to
southern Oregon and California coastal Chinook salmon populations than
to populations in the upper Klamath and Trinity rivers. The samples
from coastal rivers formed two sub-clusters: with rivers to the south
of the Klamath River in one sub-cluster and the lower Klamath River
(Blue Creek) and rivers to the north of the Klamath River in the second
sub-cluster.
We also identified ecological differences between the northern and
southern portions of the Southern Oregon and California Coastal Chinook
salmon ESU. Rivers to the north (especially the Rogue River) tended to
be larger than those to the south. River flows in the northern portion
tend to peak in January, while those to the south peak in February
(Myers et al. 1998). Annual precipitation is considerably higher in the
northern portion than in the south. Furthermore, soils in the southern
portion are highly erodible, causing high silt loads that result in
berms which close off the mouths of many of the rivers during summer
low flows. River conditions in most of these coastal basins, especially
in the south, have very limited temporal windows for adult access and
juvenile emigration.
We also considered the presence of spring-run Chinook salmon in the
northern portion of the ESU, the Rogue and Smith rivers, as a further
indicator of geographic and life history differences (although there
may have historically been a spring-run in the Eel River). Finally,
there was some ocean harvest information that indicated differences in
the migration pattern of populations from the northern (Rogue and Smith
rivers) and southern (Eel River) portions of the previously identified
Southern Oregon and California Coastal Chinook salmon ESU (Gall et al.
1989). A review of ocean distribution information collected from 1986
to 1989 (Gall et al. 1989) suggested that there may be geographic and
timing differences in the ocean distribution of Chinook salmon from the
Smith River and southern Oregon relative to the populations south of
the Klamath River.
Based on this information we concluded that SONCC Chinook salmon
met the ESU criteria because they were (1) substantially reproductively
isolated from other populations of Chinook salmon and (2) represented
an important component in the evolutionary legacy of the species.
Escapement is the number of salmon that return to spawn in a stream
or hatchery. At the time of the 1999 status review, total estimated
escapement of fall- and spring-run Chinook salmon in the Oregon portion
of the ESU was close to 100,000 fish. The largest run of fall-run
Chinook salmon in the ESU occurred in the Rogue River, where the Oregon
Department of Fish and Wildlife (ODFW) estimated an average annual
escapement of more than 51,000 fish. In addition, ODFW estimated that
the escapement of fall-run Chinook salmon to the Chetco River in 1995
and 1996 was 8,500 and 3,500 fish, respectively.
Although there were mixed trends in abundance over the long-term,
most short-term trends in abundance of fall-run Chinook salmon were
positive in the smaller coastal streams in the ESU. Spawning ground
surveys from a number of smaller coastal and tributary streams from
Euchre Creek to the Smith River showed declines in abundance from the
late 1970s through the late 1980s, but subsequent peak counts
predominantly began to show increases through the late 1990s (1988-
1998). In addition to adult counts, downstream migrant trapping
generally showed increases in production in fall-run Chinook salmon
juveniles in the 1990s in the Pistol and Winchuck rivers and in Lobster
Creek, a tributary to the lower Rogue River. Short- and long-term
trends in abundance for the Rogue River fall-run Chinook salmon were
declining, but as mentioned above, the overall run size was still
large.
Overall, the 1999 status review update indicated a continuing trend
of declining abundance for spring-run Chinook salmon. The average run
size of spring-run Chinook salmon in the Rogue River was 7,709 (1988-
1992) and the estimated percentage of hatchery fish in the run ranged
from 25 to 30 percent over that time period. The Smith River contained
the only known populations of spring-run Chinook salmon outside of the
Rogue River basin, and those runs were declining in the Middle Fork
Smith River but increasing in the South Fork Smith River.
While the status of spring-run Chinook salmon continued to be an
area of concern, the overall numbers of fall-run Chinook salmon in this
ESU and the recent increases in abundance in many of the smaller
coastal streams were considered indicators of low extinction risk. At
that time, efforts of the co-managers were also underway to improve
monitoring of Chinook salmon in this region. NMFS was concerned about
the high percentages of naturally spawning hatchery fall-run Chinook
salmon in the Chetco River and naturally spawning hatchery spring-run
Chinook salmon in the Rogue River. In addition, NMFS considered the
restricted distribution of spring-run Chinook salmon to the Rogue and
Smith River basins and their significant decline in the Rogue River as
a potentially important threat to the total diversity of fish in this
ESU.
NMFS concluded several ongoing management activities were likely to
improve the conditions for Chinook salmon in the SONCC Chinook salmon
ESU, including harvest reductions in the Klamath Management Zone troll
fishery, the ESA listing of coho salmon, changes in harvest regulations
by the States of Oregon and California to protect natural-origin coho
salmon and steelhead, and changes in timber and land-use practices on
federal public lands resulting from the Northwest Forest Plan (U.S.
Forest Service 1994). Informed by the 1999 status review update and
after considering efforts being made to improve conditions for Chinook
salmon, we determined that the ESU did not warrant listing under the
ESA (64 FR 50394, September 16, 1999).
Updated Status Reviews of OC and SONCC Chinook Salmon ESUs
To help ensure that this review was based on the best available and
most recent scientific information, we solicited information during a
60-day public comment period regarding the ESU structure and extinction
risk of the species, along with any relevant protective efforts (88 FR
1548, January 11, 2023). We also convened an OC and SONCC Status Review
Team (SRT) to review the best available scientific and commercial data
regarding the ESU structure and extinction risk of Chinook salmon in
the areas previously identified as the OC and SONCC Chinook salmon ESUs
and consistent with the scope of the listing petition.
[[Page 56997]]
Specifically, the SRT addressed (1) whether the geographic boundaries
of the previously identified ESUs warrant redelineation or refinement,
(2) the relationship to the defined ESUs of hatchery programs
propagating Chinook salmon, and (3) the level of extinction risk of the
ESUs throughout all or a significant portion of their ranges. The
status review report (SRT 2024) presents the SRT's professional
judgement of the extinction risk facing the OC and SONCC Chinook salmon
ESUs but makes no recommendation as to the listing status of the
species. The status review report (SRT 2024) is available
electronically (see ADDRESSES).
The status review report was subject to independent peer review
pursuant to the Office of Management and Budget Final Information
Quality Bulletin for Peer Review (M-05-03; December 16, 2004). The
status review report was peer reviewed by three independent scientists
selected from the academic and scientific community with expertise in
salmonid biology, conservation, and management and specific knowledge
of Chinook salmon. The SRT asked peer reviewers to evaluate the
adequacy, appropriateness, and application of data used in the status
review report, as well as the findings made in the ``Risk Assessment''
section of the report. The SRT addressed all peer reviewer comments
prior to finalizing the status review report.
We subsequently reviewed the status review report, its cited
references, and peer review comments and conclude the status review
report, upon which this 12-month finding is based, provides the best
available scientific and commercial information on the OC and SONCC
Chinook salmon ESUs. Much of the information discussed below on the ESU
configurations, demographics, threats, and extinction risks is
attributable to the status review report. We have applied the statutory
provisions of the ESA, including evaluation of the factors set forth in
section 4(a)(1)(A)-(E), our regulations regarding listing
determinations, and relevant policies identified herein in making the
listing determination. In the sections below, we provide information
from the report regarding threats to and the status of the OC and SONCC
Chinook salmon ESUs.
Review of ESU Delineations
As mentioned above, NMFS initially identified the OC and SONCC ESUs
in the late 1990s as part of the coastwide status review process
undertaken by the agency. Factors considered in delineating these ESUs
included patterns of juvenile and adult life-history variation,
freshwater ecological provinces, patterns in ocean distribution, and
patterns of genetic variation at individual loci assessed using
molecular methods. The SRT reviewed the analyses that identified the
current ESU configuration (Myers et al. 1998, NMFS 1999) and concurred
with the conclusions of those analyses. In particular, patterns of
genetic variation indicated that the OC and SONCC Chinook salmon ESUs
were substantially reproductively isolated from each other and other
Chinook salmon ESUs, and patterns of life-history, genetic, and
ecological variation indicated that each of these ESUs formed an
important component of the evolutionary legacy of the species.
In the intervening decades, the most marked change in population
information has been the analysis of additional genetic variation,
along with some updates to information on ocean distribution. The SRT
reviewed the available genetic and ecological information obtained
since the original ESU designations. The SRT found an additional five
studies published subsequent to 1998-1999 that included coast wide
samples of Chinook salmon analyzed for genetic variation. The SRT found
that the genetic data collected over the past ~20 years generally
continues to support the OC and SONCC ESU boundaries identified in the
coastwide status review (Myers et al. 1998) and status review update
(West Coast Chinook Salmon Biological Review Team 1999). In particular,
the status reviews differentiated genetic samples from the OC and SONCC
into distinct groups, providing evidence in support of both the
reproductive isolation and evolutionary legacy prongs of the ESU
definition. There are, however, some exceptions that the SRT noted and
discussed.
The SRT noted a study by Kinziger et al. (2013) that presented
updated information related to the boundary between SONCC and the Upper
Klamath-Trinity River (UKTR) Chinook salmon ESU. Previously, we
included all Chinook salmon upstream of the confluence of the Klamath
and Trinity rivers in the UKTR Chinook salmon ESU (63 FR 11482, March
9, 1998). Genetic patterns described by Kinziger et al. (2013) are
consistent with this boundary, with the exception of the sample from
Horse Linto Creek. Horse Linto Creek is a small tributary of the
Trinity River above the confluence of the Trinity River with the
Klamath River, but the Horse Linto Creek sample is more genetically
similar to SONCC samples from streams below the Trinity River
confluence. Despite this discrepancy, the SRT concluded that current
boundary between the SONCC and UKTR ESUs should remain at the
confluence of the Trinity and Klamath rivers. The SRT acknowledged that
genetic samples from Horse Linto Creek (above the confluence) from a
single year were genetically more similar to SONCC than to UKTR.
However, the SRT considered that this small stream could well function
as a transition zone between these two ESUs and might well change its
genetic structure from time to time depending on the composition of the
returns. The SRT therefore did not consider the available information
to be sufficient to change the ESU boundary, but they encouraged
continued collecting of genetic data from that area.
The SRT also noted some uncertainty regarding Chinook salmon in the
Umpqua River. The previous status review (Myers et al. 1998) concluded
that Chinook salmon in the Umpqua River were part of the OC Chinook
salmon ESU, despite some genetic similarity of a Rock Creek Hatchery
(in the Umpqua River Basin) to samples from the SONCC Chinook salmon
ESU. Based on a review of several additional studies, the SRT found
that both hatchery- and natural-origin spring (but not fall) Umpqua
River Chinook salmon are genetically different from other OC
populations. In particular, the Umpqua River spring-run Chinook salmon
appear to be genetically similar to the SONCC (spring and fall). The
Umpqua River spring-run Chinook salmon also are similar to SONCC
Chinook salmon in their ocean distribution patterns and age structure.
The SRT considered that historical releases of out-of-basin spring-run
Chinook salmon from the Rogue and Columbia River basins are a likely
explanation for this pattern, but the SRT also considered the
possibility that spring-run Chinook salmon from the Rogue River might
sometimes naturally stray into the Umpqua River or that there are older
evolutionary connections between spring-run Chinook salmon in the Rogue
and Umpqua Rivers. While acknowledging this uncertainty, the SRT
nonetheless concluded that both natural and hatchery-origin spring-run
Chinook salmon in the Umpqua River are part of the OC ESU, consistent
with the original 1998 review. This conclusion was based on the
integrated nature of the Rock Creek Hatchery broodstock, which
regularly incorporates natural-origin fish returning to the Umpqua
River, and the continuous recorded presence of natural-origin spring-
run Chinook salmon in the Umpqua River since the early 1900s.
[[Page 56998]]
Another factor Myers et al. (1998) used to differentiate Chinook
salmon ESUs is their ocean distribution. Chinook salmon ocean
distribution depends strongly on region of origin and has a genetic
basis (Myers et al. 1998, SRT 2024). We can infer ocean distribution
from coded wire tag recoveries in commercial and recreational ocean
fisheries. Because the vast majority of coded wire tagged Chinook
salmon come from hatchery populations, we must also infer the migratory
routes of natural-origin fish from their corresponding hatchery
populations.
The SRT compared the more recent published analyses of spatial
differences in ocean distribution (Weitkamp 2010, Shelton et al. 2019,
2021) to the information presented in Myers et al. (1998). Two of the
four OC Chinook salmon ESU stocks, the Trask River and Salmon River
fall-run stocks, have a clearly northern distribution. The Umpqua River
spring-run Chinook salmon stock appears to have a more southerly
distribution, with a larger proportion of coded wire tag recoveries in
Oregon and California than other OC stocks. The SRT also noted from the
data that Chinook salmon from the Umpqua River show a younger ocean age
structure more similar to Chinook salmon from SONCC populations than
other OC populations.
The fourth OC Chinook salmon ESU stock, the Elk River fall-run
stock, appears to have an intermediate ocean distribution between
Salmon River fall-run and Umpqua River spring-run stock distributions.
However, a directed fishery near the mouth of the Elk River has a
substantial influence on the coded wire tag recovery data.
In the SONCC Chinook salmon group, commercial and recreational
fisheries recover coded wire tags from the Rogue River spring-run and
fall-run Chinook salmon stocks almost exclusively off the coasts of
Oregon and California. Similarly, fisheries recover coded wire tags
from the Chetco River fall-run stock predominantly off Oregon and
northern California in both the summer and fall. The SRT also noted
that ocean distribution for SONCC Chinook salmon ESU is very similar to
ocean distribution of fall- and spring-run Chinook salmon from the
upper Klamath River.
As a result of all this, the SRT concluded, and we agree, that the
patterns of genetic variation continue to support the originally
defined ESU boundaries. Updated evaluations of adult ocean distribution
were also consistent with the information originally used to identify
the ESUs.
ESU Membership of Hatchery-Origin Chinook Salmon
In 2005, we issued a policy for considering hatchery-origin fish in
ESA listing determinations (Hatchery Listing Policy; 70 FR 37204, June
28, 2005). Under the Hatchery Listing Policy, we consider a hatchery
stock to be part of an ESU if it exhibits a level of genetic divergence
relative to the local natural population(s) that is no more than what
occurs within the ESU (70 FR 37215, June 28, 2005). We recognize that
there are a number of ways to compute and compare genetic divergence
and that it is not possible to sample all fish within the ESU to
precisely determine the range of genetic diversity within an ESU. In
factoring artificial propagation into the extinction risk assessment
for an ESU, we evaluate potential risks to the naturally-spawned
components of the ESU posed by hatchery programs determined not to be
part of the ESU and look at the potential benefits and risks to the
naturally-spawned components of the ESU posed by hatchery programs
determined to be part of the ESU.
Below, we summarize information on the current hatchery practices
and the source broodstocks for the hatcheries. We consider hatchery
programs for Pacific salmon and steelhead to be either ``integrated''
or ``isolated'' based on the genetic management goals and protocols for
propagating a hatchery broodstock. We would consider a hatchery program
to be genetically integrated if a principal goal is to minimize
potential genetic divergence between the hatchery broodstock and a
naturally-spawning population. Genetically integrated programs
systematically include natural-origin fish in the broodstock each year
or generation. We would consider hatchery programs to be genetically
isolated if the principal goal is to produce a reproductively distinct
population primarily, if not exclusively, from adult returns back to
the hatchery. In isolated programs, little or no gene flow should occur
from a naturally spawning population to the hatchery broodstock.
OC Chinook Salmon ESU Hatchery Stocks
Artificial propagation efforts for OC Chinook salmon began in the
late 1890s. By the early 1900s, there were hatcheries and egg-take
stations on most of the larger streams on the Oregon coast, especially
the Yaquina, Alsea, Siuslaw, Umpqua, Coos, and Coquille Rivers (Cobb
1930, Wahle and Smith 1979). In addition to local stocks, there is a
history of hatchery programs using out-of-basin stocks. Prior to the
1960s, a substantial portion of the hatchery fish released in OC river
basins came from the lower Columbia River--mostly from the Bonneville
and Clackamas Hatcheries (Myers et al. 1998). There are several
hatcheries currently producing fall-run and spring-run Chinook salmon
in the OC Chinook salmon ESU. These hatcheries release Chinook salmon
into the Necanicum, Trask, Nestucca, Salmon, Umpqua, Coos, Coquille and
Elk river basins.
ODFW manages the Trask River hatchery fall-run and spring-run
Chinook salmon stocks as segregated stocks (ODFW 2023). In addition to
the Trask River, ODFW releases the fall-run stock into the Necanicum
River. For the years 2014 through 2021, the Trask River hatchery
included an average of 12 percent natural-origin fish in the fall-run
Chinook salmon broodstock annually (ODFW 2024). The hatchery rarely
includes natural-origin fish in the spring-run Chinook salmon
broodstock. Although the Trask River hatchery has largely derived its
fall-run and spring-run stock from adults returning to the Trask River,
historically there were considerable transfers from out-of-basin stocks
including a hatchery stock known as the ``Lower Columbia River/Oregon
Coast Mix'' and fish from the Nestucca, Rogue, and Umpqua Rivers (Myers
et al. 1998).
Within the Nestucca River basin, ODFW operates a hatchery on Cedar
Creek that produces fall-run and spring-run Chinook salmon. Historical
records for Cedar Creek Hatchery (1955-1959) indicate that past
hatchery managers released Chinook salmon from the lower Columbia River
and Oregon coast into Cedar Creek, but the records do not specify the
run timing. Since 1975, ODFW has managed the spring-run program as a
segregated stock, with few if any natural fish incorporated annually
into broodstock. The hatchery began annual releases of fall-run Chinook
salmon in 1975 but suspended the program in 1993. ODFW restarted the
fall-run Chinook salmon program in 1999 using local broodstock and for
the years 2014 through 2021 has annually integrated an average of 21
percent naturally-produced fish in the broodstock (ODFW 2024).
According to ODFW, the goal of the current Salmon River hatchery
program is to have the hatchery fish mimic the characteristics of the
naturally reproducing fall-run Chinook salmon population (ODFW 2023).
In furtherance of this goal, hatchery program staff annually attempt to
incorporate naturally-produced fish at a rate of 50 percent in the
broodstock. ODFW has
[[Page 56999]]
met this broodstock goal in 2 of the last 5 years. Records (although
likely incomplete) do not indicate the release of any non-native fall-
run Chinook salmon into the Salmon River basin.
The Elk River fall-run Chinook salmon hatchery program began in
1968 with the first smolts released in 1969. Records indicate there
have been few transfers of fall-run Chinook salmon from out-of-basin
sources (Myers et al. 1998). ODFW classifies the Elk River fall-run
program as an isolated program but incorporates a small proportion of
natural-origin fish in the broodstock annually (14 percent, 2014-2021).
According to ODFW (2016), no purposeful or inadvertent selection has
been applied to change characteristics of the founding broodstock. ODFW
staff have detected no genetic, phenotypic, or ecological differences
between hatchery and natural-origin Elk River fall-run Chinook salmon.
The Umpqua River spring-run Chinook salmon program at Rock Creek
began in 1950 using local broodstock. The Umpqua River spring-run
Chinook salmon program became an integrated program, and for the years
2014 through 2021 23 percent of the broodstock was of natural origin
(ODFW 2024). Prior to the initiation of the Rock Creek Hatchery
Program, there were transfers of spring-run Chinook salmon from the
Rogue, Trask, and Imnaha rivers (ODFW 1954, Wallis 1963). Prior to
1997, the Umpqua River fall-run Chinook salmon program collected
broodstock from the South Umpqua River. From 1997 until 2000, the
program used broodstock from the lower Umpqua River brood and over 90
percent of the broodstock used by the program were natural-origin
Chinook salmon. In 2000, the program began capturing returning hatchery
fish at Winchester Creek. The goal of the program is to integrate at
least 10 percent natural-origin fish into the broodstock. Myers et al.
(1998) noted that there have been some transfers into the Umpqua River
basin from non-native sources, including the Columbia River and other
Oregon coast tributaries.
ODFW initiated the current Coos River fall-run Chinook salmon
hatchery program in 1982 with local broodstock, though private
aquaculture facilities, as described below, used out-of-basin stocks.
Although the intent of the program is to integrate natural-origin fish
into the broodstock, ODFW (2023) reported that the program has included
few natural-origin fish. ODFW monitoring summaries indicate from 2014
through 2021, ODFW incorporated natural-origin fish in two years and in
low numbers. Private aquaculture facilities have also operated in the
Coos River basin. During the 1980s, private aquaculture facilities
released both fall- and spring-run Chinook salmon that originated
primarily from out-of-basin stocks, including some 23 million fall-run
Chinook salmon from Anadromous, Inc., and Oregon Aqua Foods (Myers et
al. 1998).
Myers et al. (1998) reported that there have been numerous releases
of non-local fish into the Coquille River, primarily from the Coos
River, Bonneville (Lower Columbia River), Chetco, and Elk River
hatcheries. ODFW currently maintains two fall-run Chinook salmon
hatchery programs in the Coquille River basin. ODFW initiated the
primary program in 1983 using Coquille River basin broodstock with a
goal of increasing the harvestable numbers of fish. In 2022, ODFW
started a second program designed to serve as a conservation program
using the same local broodstock. The Coquille River fall-run Chinook
salmon population is considered to be at high risk, and the
conservation hatchery program is an emergency measure to prevent its
extinction (ODFW 2022).
Based on their local origin and the integrated nature of the
programs, we conclude that the fall-run and spring-run Chinook salmon
hatchery stocks from the majority of the hatchery programs meet the
criteria to be considered part of the OC Chinook salmon ESU. The only
exception is the spring-run Chinook salmon stock from the Trask and
Nestucca hatchery programs. The SRT concluded that these stocks are
genetically distinct from most natural-origin fish in these basins. The
genetic distinctness of these stocks is likely due to a combination of
documented out-of-basin introductions and a long history of using only
hatchery-origin fish for broodstock (SRT 2024). Although the SRT
acknowledged limited use of local brood stock for the Coos River fall-
run program, the SRT ultimately considered this part of the OC Chinook
salmon ESU. We therefore conclude that the spring-run hatchery stocks
from the Trask and Nestucca programs are not part of the OC Chinook
salmon ESU.
SONCC Chinook Salmon ESU and Hatchery Stocks
Hatchery programs have been operating in the Rogue River basin
since 1877. ODFW began construction and operation of the Butte Falls
hatchery in 1916. The Butte Falls hatchery program produced salmon and
steelhead for release into the Rogue River basin from the 1940s until
the construction of Lost Creek Dam and the associated Cole Rivers
Hatchery on the upper Rogue in 1978. The Cole Rivers spring-run Chinook
salmon hatchery broodstock originated from Rogue River natural-origin
fish. The purposes of the program are to augment fishing and harvest
opportunities and mitigate the loss of habitat resulting from the
construction of dams on the Rogue and Applegate Rivers (ODFW 2024).
The fall-run Chinook salmon program at the Indian Creek Hatchery in
the Rogue River basin began in 1986 using fish from a hatchery stock
known as ODFW stock 61. Prior to 1989, hatchery fall-run Chinook salmon
releases consisted of Upper Rogue River stock (ODFW stock 052). Since
1991, the hatchery program has collected broodstock of both hatchery
and natural origin from the Lower Rogue River (ODFW stock 61).
The Chetco River fall-run Chinook salmon hatchery program began in
1968 using local Chetco River Chinook salmon broodstock (ODFW stock
96). There were non-native releases of fall-run Chinook salmon from the
Elk, Coquille, and unknown hatchery sources during the 1960s and 1970s,
although the majority of releases appear to be of Chetco River origin
(Myers et al. 1998).
The Rowdy Creek fish hatchery in the Smith River basin produces
fall-run Chinook salmon. According to the Hatchery Genetic Monitoring
Plan (HGMP) (Tolowa Dee-ni' Nation 2018), the Tolowa Dee-ni' Nation
operates the Rowdy Creek hatchery program as an integrated program
incorporating natural-origin fish in the broodstock.
Based on their local origin and the integrated nature of the
programs, we conclude that the Rogue River, Chetco River, and Smith
River hatchery stocks meet the criteria to be considered part of the
SONCC Chinook salmon ESU.
Determination of Species
OC Chinook Salmon ESU
Based on the information above, we conclude that the OC Chinook
salmon ESU constitutes a species under the ESA and includes coastal
populations of fall- and spring-run Chinook salmon from the Elk River
north to the mouth of the Columbia River, as well as the fall- and
spring-run Chinook salmon hatchery stocks in the Necanicum, Salmon,
Umpqua, Coos, Coquille, and Elk rivers and the fall-run hatchery stocks
in the Trask and Nestucca rivers.
SONCC Chinook Salmon ESU
Based on the information above, we conclude that the SONCC Chinook
salmon ESU constitutes a species under the ESA and includes coastal
[[Page 57000]]
populations of fall- and spring-run Chinook salmon from Euchre Creek,
Oregon, through the Lower Klamath River (below the confluence of the
Klamath and Trinity rivers), California (inclusive), as well as the
fall- and spring-run Chinook salmon hatchery stocks in the Rogue River,
Chetco River, and Smith River.
Assessment of Extinction Risk
The SRT synthesized the best scientific and commercial data
available regarding the ESU's status, which includes its life history,
demographic trends, and susceptibility to threats, and evaluated the
extinction risk of each ESU. The SRT included in its assessment an
evaluation of the likely effects of hatchery-origin fish on the
viability of the ESU. The SRT's extinction risk assessment reflects the
SRT's professional scientific judgment, guided by the analysis of the
demographic risks and threats.
Demographic Risk Analysis
The SRT assessed demographic risk using four key viability
criteria: abundance, productivity, spatial structure, and diversity. A
summary of our evaluation follows, with a detailed discussion of the
demographic risk analysis available in SRT (2024). The demographic risk
analysis compared current to historical abundance and evaluated recent
trends in abundance. The SRT calculated average abundance as a 5-year
geometric mean. Salmonid abundance data tend to be skewed by the
presence of outliers (observations considerably higher or lower than
most of the data). For skewed data, the geometric mean is a more stable
statistic than the arithmetic mean. The SRT calculated population
trends over 15-year windows.
OC Chinook Salmon ESU
The OC Chinook salmon ESU consists of 18 fall-run and 2 spring-run
populations (ODFW 2014a). The fall-run Chinook salmon life-history
pattern is numerically more abundant, with populations present in all
major rivers between the Nehalem River in the north and Elk River in
the south. Salmon with early-run (spring- or summer-run) life histories
are present in many of the same rivers, including the Nehalem,
Tillamook, Nestucca, Siletz, Alsea, and Coquille, where they are
considered to be demographically part of the same populations as the
fall runs, with the exception of the Umpqua River where the spring runs
are considered to be separate populations from the fall run (ODFW
2014a). The two spring-run populations occupy the north and south forks
of the Umpqua River.
Recent information on fall-run Chinook salmon abundance (1986-2021)
show that for 14 monitored populations, 13 have spawning abundance in
the thousands to tens of thousands and most have relatively stable
abundances over the past 35 years (SRT 2024). There are several notable
exceptions to this pattern, however, with the Coquille, Tillamook, and
Siuslaw populations at or near their lowest abundance of the time-
series in 2021. Overall, population trends in the most recent 15-year
period (2008-2022) are relatively stable. Population trends are
positive (increasing trend) for half of the fall-run populations and
negative (decreasing trend) for the other half. This relative stability
has occurred despite ocean and freshwater harvest that together capture
between 40 and 50 percent of each cohort on average (see OC Chinook
Salmon ESU and Harvest).
Most of the fall-run fish in this ESU are of natural origin. Only
four populations have more than a 5 percent contribution of hatchery-
origin spawners in any 1 year between 2014 and 2020 (SRT 2024). The two
populations with a long history of substantial hatchery production (Elk
and Salmon rivers) both show a trend toward increased natural spawners
since the late 1990s.
The combined number of natural-origin spawners in the Umpqua River
spring-run Chinook salmon populations has been at or below 5,000
individuals in recent years (1986-2022; SRT 2024). Longer time series
are available since 1946 for spring-run fish passing Winchester Dam on
the North Umpqua River and suggest relative stability of spring-run
abundance since about 1960 (note that fisheries and other sources of
mortality occur upstream of Winchester Dam and so abundance at the dam
is not equivalent to spawning escapement). Hatchery-origin individuals
contribute more to the North Umpqua spring-run spawners than any of the
fall-run stocks, but since 2000, the trend is toward more natural-
origin spawners (SRT 2024).
Aggregating across runs, since 1986, OC Chinook salmon ESU spawning
escapements ranged between about 45,000 and 190,000 individuals
annually. While there have been some substantial swings in abundance
over the past 35 years, the trend in aggregate abundance appears to be
roughly flat. In most years, greater than 90 percent of spawners in the
OC Chinook salmon ESU are fall-run salmon, and the vast majority are of
natural origin.
SONCC Chinook Salmon ESU
The SONCC Chinook salmon ESU consists of 8 fall-run and 2 spring-
run populations. Similar to OC Chinook ESU, the fall-run Chinook salmon
life-history pattern is numerically more abundant. Within the SONCC
Chinook salmon ESU, fall-run Chinook salmon occupy the Euchre and
Hunter creeks and the Rogue, Pistol, Chetco, Winchuck, Smith and lower
Klamath rivers (specifically Blue Creek but also other small
tributaries). The Rogue River contains the largest population of
spring-run Chinook salmon with smaller numbers recorded in the Smith
River. ODFW (2007b) also notes that surveys have observed a few spring-
run Chinook salmon in the Applegate, Pistol, Illinois, and Chetco
rivers.
The SRT estimated a 5-year annual abundance of 31,709 natural-
origin fall-run spawners (2016-2020) and 5,454 natural-origin spring-
run spawners (2018-2022) in the Rogue River basin. The SRT estimated
that the 5-year average annual abundance for the remaining 5 fall-run
populations with data (Blue Creek, Chetco River, Pistol River, Winchuck
River, and Hunter River) ranged from 185 (Blue Creek) to 1,899 (Chetco
river) natural-origin spawners (2016-2020). The SRT found anecdotal
evidence indicating that there may be thousands of Chinook salmon
(hatchery- and natural-origin combined) in the Smith River. The Smith
River has had a number of surveys occurring in different parts of the
river between 1980 and 2021, but there are no consistent system-wide
estimates of spawner abundance for this basin. Due to the data
consistency issue, the SRT did not include the Smith River in trend
analyses.
The SRT estimated trends in abundance for fall-run populations for
three 15-year periods: 1986-2001, 1997-2011, and 2007-2021. With the
exception of Blue Creek, trends for fall-run populations were negative
for the two most recent 15-year periods. Blue Creek exhibited a
positive trend in the 1997-2011 time period, negative in the more
recent time period. The SRT noted that although the majority of the
fall-run populations exhibited negative trends in abundance in the two
recent time periods, collectively, fall-run Chinook salmon abundance in
2021 was similar to other troughs in the time-series (e.g., 1990-1991,
2006-2008).
The SRT estimated trends in abundance of spring-run Chinook salmon
in the Rogue River for five 15-year periods: 1948-1962, 1963-1977,
1978-1992, 1993-2007, and 2008-2022. The recent 5-year geometric mean
of
[[Page 57001]]
natural-origin spring-run spawners in the Rogue River was 5,454 (2018-
2022; SRT 2024). This is considerably lower than the pre-1990
abundance, which was typically >15,000 and commonly >30,000. Abundance
of spring-run Chinook salmon in the Rogue River basin was relatively
stable from 1948 to 1962 followed by a substantial negative trend from
the middle of the 1960s through the early 1990s. By the middle of the
1990s trends in abundance began to level off and have been relatively
flat since (SRT 2024).
Available data suggest that the proportion of natural-origin
spawners was high for all fall- and spring-run populations throughout
the time-series (greater than 70 percent). This occurs despite
substantial hatchery production for both fall- and spring-run Chinook
salmon in the Rogue River. For the spring-run population, ODFW (2019)
reported that the percentage of hatchery fish among Chinook salmon
spawning naturally in the Rogue River averaged 5 percent over the 10-
year period from 2008-2017. For the fall-run populations, a lack of
monitoring data for fish by natural- versus hatchery-origin (with the
notable exception of the lower Rogue) makes it difficult to determine
the exact contribution of fall-run hatchery fish to natural spawners in
the Rogue.
Data for the Smith River, a sizable population, were insufficient
to evaluate trends. Several estimates for the Smith River from 2010 to
2021 were between 10,000 and 20,000 fall-run Chinook salmon, suggesting
that it is likely the second largest population in the ESU. If these
numbers are accurate, that would suggest the overall fall-run Chinook
salmon spawner abundance for the SONCC ESU would have been 60,000-
70,000 in 2021.
Analysis of Section 4(a)(1) Factors
As described above, section 4(a)(1) of the ESA and NMFS'
implementing regulations (50 CFR 424.11(c)) state that we must
determine whether a species is endangered or threatened because of any
one or a combination of the following factors: the present or
threatened destruction, modification, or curtailment of its habitat or
range; overutilization for commercial, recreational, scientific, or
educational purposes; disease or predation; the inadequacy of existing
regulatory mechanisms; or other natural or manmade factors affecting
its continued existence. We evaluated whether and the extent to which
each of the foregoing factors contributes to the overall extinction
risk of the OC and SONCC Chinook salmon ESUs. A summary of our
evaluation follows. See SRT (2024) for a detailed discussion of the ESA
section 4(a)(1) factors.
NMFS has discussed the impacts of various factors contributing to
the decline of Pacific salmon and steelhead in previous listing
determinations (e.g., 63 FR 11482, March 9, 1998; 69 FR 33102, June 14,
2004) and supporting documentation (e.g., NMFS 1996, NMFS 1997, NMFS
1998). In each case, we concluded that all of the factors identified in
section 4(a)(1) of the ESA had played a role in the decline of West
Coast Chinook salmon. More recently, we reviewed and provided a
detailed analysis of these factors for the ESA-listed OC and SONCC coho
salmon (Oncorhynchus kisutch) ESUs, which overlap the OC and SONCC
Chinook salmon ESUs (NMFS 2014, 2016, and 2022; Stout et al. 2012).
Because of the similarities in life-history strategies and associated
habitat types for coho and Chinook salmon (SRT 2024), this section
draws largely from NMFS' previous listing determinations and supporting
documentation.
The Present or Threatened Destruction, Modification, or Curtailment of
Its Habitat or Range
The complex life cycle of Chinook salmon gives rise to complex
habitat needs, particularly during the freshwater phase (Bjornn and
Reiser 1991; Spence et al. 1996; Quinn 2018). Spawning gravels must be
of a certain size and free of sediment to allow successful incubation
of the eggs. Eggs require cool, clean, and well-oxygenated waters for
proper development. Juveniles need abundant food sources, including
insects, crustaceans, and other small fish. Juveniles need places to
hide from predators (mostly birds and bigger fish), such as under logs,
root wads and boulders in the stream and beneath overhanging
vegetation. They also need places to seek refuge from periodic high
flows (side channels and off channel areas) and from warm summer water
temperatures (cold water springs and deep pools). Returning adults
generally do not feed in fresh water but instead rely on limited energy
stores to migrate, mature, and spawn. Like juveniles, they also require
cool water and places to rest and hide from predators. During all life
stages salmon require cool water that is free of contaminants. They
also require rearing and migration corridors with adequate passage
conditions (water quality and quantity available at specific times) to
allow access to the various habitats required to complete their life
cycle.
Our previous Federal Register notices and reports (NMFS 1996, 1997,
1998, 2014, 2016; Stout et al 2012), as well as numerous other reports
and assessments (Kostow 1995; National Research Council 1996; Spence et
al 1996; Nicholas et al. 2005; ODFW 2007a, 2007b, 2013, 2014c, 2021),
have reviewed in detail the effects of historical and ongoing land-
management practices that have altered Oregon and California coastal
salmon habitat. A major determinant of trends in salmon abundance is
the condition of the freshwater, estuarine, and ocean habitats on which
salmon depend. While we rarely have sufficient information to predict
the population-scale effects of habitat loss or degradation with
precision, it is clear that habitat availability imposes an upper limit
on the production of salmon, and reduction in habitat area or quality
reduces potential production.
A broad range of historical and ongoing land and water-management
activities and practices have adversely impacted the freshwater and
estuarine habitats used by Chinook salmon, including construction of
dams and other barriers, water diversions, channelization and diking,
agricultural practices, roads, timber harvest, mining, and urban
development. In the 1850s, settlers began developing the flat alluvial
valley bottoms and filling wetlands to increase agricultural
productivity in the OC and SONCC Chinook salmon ESUs' ranges. In the
years that followed, people straightened and disconnected stream
channels from their floodplains, diked, drained and filled wetlands
associated with historically braided river channels and estuaries,
eliminated beaver and their ponds, and negatively modified riparian
habitats (Kostow 1995; Nicholas 1997).
By the mid-1800s, placer mining (mining of stream bed deposits for
minerals, especially gold) became a major industry in the Pacific
Northwest. Mineral and sand and gravel mining can alter riparian
habitats, streambanks, channel morphology, floodplain function, bed
material composition, and instream habitat complexity (NRC 1996).
Mining can also pollute streams by increasing in-stream sediment loads
and by releasing toxic heavy metal and acids (Meehan 1991). The hand
methods used in the early days of placer mining later gave way to
hydraulic mining and dredging. Placer mining in the 1800s destroyed
spawning and rearing habitats either directly or through increased
sedimentation, and in some areas, mine wastes still affect water
quality and riparian function (NMFS 1997). Motorized in-stream placer
mining is another common form of mining that impacted salmon habitats.
California banned motorized in-stream placer
[[Page 57002]]
mining in 2016 and Oregon banned it in 2018.
Timber harvesting and associated road building are widespread
throughout the range of both the OC and SONCC Chinook salmon ESUs. The
immediate effects of these activities were the loss of important
habitat features. Efforts to ``clean'' the stream channel for fish
passage began in the 1940s and continued through the 1970s (Reeves et
al. 1991). The principal consequences of these activities include
changed rates of sediment and nutrient delivery, increased fine
sediment levels, reduced levels of instream large wood, altered levels
of temperature and dissolved oxygen, and altered watershed hydrology
(Meehan 1991). The Forest Ecosystem Management Assessment Team (FEMAT
1993) characterized forest road networks as the most important sources
of accelerated delivery of sediment to fish-bearing streams. While
timber harvest activity has decreased since the peak over 50 years ago,
and timber harvest practices and forest management have improved, the
effects of past timber harvest practices and road building continue and
future timber harvest (particularly on private lands) may pose a threat
to Chinook salmon. The threat from future timber harvest will rely
partly on the states' forest practices and the forest practices for
federal lands (see Inadequacy of Existing Regulatory Mechanisms).
Agricultural activities reduced instream flows through water
diversions and altered stream stability by removing stream-side
vegetation and through the building of dikes and levees that
disconnected streams from their floodplains and resulted in loss of
natural stream sinuosity. Urban development has also led to building of
roads by streams, stream channelization, and loss of instream wood in
some areas. Urban, industrial, and rural developments can also result
in increased peak flows, simplification of downstream channels,
increased channel width to depth ratios, and toxic non-point source
pollution (Booth and Jackson 1997, Booth and Steinemann 2006).
Agricultural land conversion and urban, industrial, and rural
development are also the primary causes of freshwater and estuarine
wetland losses. Wetlands are important rearing habitat for Chinook
salmon.
Roads can contribute to the degradation of salmonid habitat in
several ways. ``Roads can affect salmonid habitat by reducing natural
infiltration and increasing hydro-confinement, leading to altered flow
regimes, [and] peak flows. . . .'' (NMFS 2013). Roads also increase
sediment loads in streams ``due to mass failures of cut and fill slopes
and channelized surface erosion'' (Spence et al. 1996). By increasing
the magnitude and frequency of peak flows, roads can cause excess
scouring of downstream stream beds and banks. Lastly, ``runoff from
roads in urban areas can contain significant concentrations of
substances that are toxic to fish'' (Spence et al. 1996).
Dams affect the way water and sediment move down a river, changing
the amount and timing of flow, the size of substrates downstream of the
dam, and the temperature and chemical characteristics (NMFS 2013 and
2014). And because dams transform the upstream habitat from a river
into a lake, they change the amount and location of available habitat
and significantly alter salmonid interactions with predators and
competitors. Dams can also act as barriers to juvenile salmon migrating
to the ocean, and as obstacles to adult fish returning to their natal
streams to spawn.
NMFS (1998) identified all of the factors described above as
factors contributing to the decline of West Coast Chinook salmon. Below
we summarize the key habitat-related factors that may be currently
limiting the viability of the OC and SONCC Chinook salmon ESUs in
particular.
OC Chinook Salmon ESU and Habitat
Numerous evaluations have identified the loss of stream complexity
as one of the key factors limiting the distribution and abundance of
Chinook and coho salmon (NMFS 1996, 1997, 2016, and 2022; Nicholas
1997; Stout 2012; ODFW 2021). ODFW (2007a) defines stream complexity as
the ability of a stream to provide the typical variety of habitats.
ODFW's Oregon Coast Coho Assessment (Nicholas et al. 2005) identified
stream complexity as either a primary or secondary limiting factor
throughout all basins of the ESU. In addition to stream complexity,
ODFW (2007a) identified water quality, water quantity, hatchery
impacts, spawning gravel and exotic species as factors limiting the
distribution and abundance of salmonids.
The state of Oregon, as well as federal land and natural resource
management agencies, have made great progress towards addressing many
of the habitat limiting factors described above. ODFW recently
completed a 12-year review of the OC coho conservation plan and
included an evaluation of habitat trends (ODFW 2021). In their
evaluation of habitat trends, ODFW observed signs of improvement in
pool frequency and channel shade. ODFW also observed a flat trend in
percent fine sediments and wood volume. The detection of positive
trends and the lack of undesirable trends suggests progress in
arresting further declines in habitat conditions.
Similar to ODFW's 12-year review for OC coho salmon, NMFS (2022)
observed improvements in habitat conditions. NMFS (2022) noted the
restoration of thousands of acres of off channel habitat in estuarine
and freshwater areas, restoration of fish passage and access to
tributary habitats, and the continued implementation of existing
management plans and regulations that reduce impacts to freshwater
habitats. ODFW's analysis of habitat trends and NMFS' assessment for
the OC Coho salmon ESU are directly relevant to the OC Chinook salmon
ESU.
The SRT used a risk matrix to evaluate if the present or threatened
destruction, modification, or curtailment of the OC Chinook salmon
ESU's habitat or range is currently contributing to a risk of
extinction or is likely to contribute to a risk of extinction in the
foreseeable future. There has been a long history of land-use practices
leading to habitat degradation, but freshwater habitat has been
improving slowly over the past several decades due to stricter land-use
regulations compared to the early 20th century. The existing regulatory
frameworks and continued conservation efforts are generally expected to
support a positive trend in salmon habitat recovery for the foreseeable
future. The SRT concluded, and we agree, it is unlikely that this
factor contributes significantly to a risk of extinction. Although past
resource management practices negatively impacted the species habitat
and range, we find that habitat destruction and modification is not a
factor limiting the rangewide viability of the OC Chinook salmon ESU
now or in the foreseeable future.
SONCC Chinook Salmon ESU and Habitat
A wide variety of past and present activities have impacted
salmonid habitat within the SONCC Chinook salmon ESU. The primary
factors that may be limiting the productivity of the habitat to some
degree are water quality, water quantity, habitat complexity, and
access to off channel habitats. The water quality problems include
excess temperatures, flow modification, sedimentation, and bacterial
contamination. The causes for these problems are various and include
the legacy and ongoing effects of land and resource management, urban,
rural, industrial, and agricultural developments, and dams.
[[Page 57003]]
Since the last status review the state of California's Fisheries
Restoration Grants Program (FRGP) and Oregon's Watershed Enhancement
Board (OWEB) have funded numerous habitat restoration projects in the
SONCC Chinook salmon ESU (CalFish 2024, OWEB 2024). The types of
projects include riparian habitat improvement, instream habitat
improvement, and fish passage improvement. In the past 23 years (2000
through 2023), the FRGP funded 48 habitat restoration projects in river
basins that support SONCC Chinook salmon. In the past 22 years (2000 to
2022), OWEB funded 63 habitat restoration projects in basins that
support SONCC Chinook salmon. In addition to the actions funded through
these programs, several dams have been removed in the Rogue River
basin. Savage Rapids and Gold Ray dams on the upper Rogue River have
been removed. Elk Creek dam, Jackson Street dam on Bear Creek, and
Lovelace and Santilla Fish Farm dams on Slate Creek have also been
removed.
The Rogue River basin contains two dams operated by the U.S. Army
Corps of Engineers (USACE). In 1977, the USACE completed construction
of the William Jess Dam on the mainstream Rogue River at river mile
157. Because the dam does not have fish passage it blocks access to
approximately 25 percent of the primary spring-run Chinook salmon
spawning habitat in the basin (Kostow 1995, ODFW 2007b). The USACE
completed construction on the Applegate Dam on the upper Applegate
River in 1979. The USACE manages the water stored in the reservoirs
created by the William Jess and Applegate dams for multiple purposes,
one of which is to increase the amount of downstream habitat for
juvenile salmonids. This operational strategy has successfully enhanced
habitat for juvenile Chinook salmon in the Rogue River as evidenced by
the increase in flow during the summer rearing period (ODFW 2007b).
USACE operation of Applegate Dam affects flow in the Applegate River
during autumn to aid the upstream migration of adult Chinook salmon.
The operational strategy has been successful in enhancing the available
spawning habitat of fall-run Chinook salmon in the Applegate River
(ODFW 2013). Prior to construction of Applegate Dam, 90 percent of
fall-run Chinook salmon spawning in the Applegate River occurred in the
lower 13 miles of the river. After dam construction and due largely to
reservoir operation, spawning shifted upstream with an average of 33
percent of spawners found above that same point (ODFW 2013).
Dams can also alter natural sediment transport processes and
decrease the recruitment of coarse materials (e.g., spawning gravels)
into downstream habitats (Spence et al. 1996, ODFW 2000). ODFW (2007b,
2013, and 2024) has documented a reduction in spawning gravel linked to
the dams in both the Rogue and Applegate rivers. The USACE has funded
efforts to supplement instream gravel below the Lost Creek dam, and
ODFW expects those efforts to begin in 2025 (ODFW 2024).
The recent removal of four dams (Iron Gate, Copco 1, Copco 2, and
J.C. Boyle) on the upper Klamath River will improve downstream habitat
conditions and water quality in the lower Klamath River basin. However,
water diversions in the Upper Klamath River, the Trinity River, and the
Scott and Shasta Rivers decrease the total volume of water that
otherwise would have naturally flowed down the Lower Klamath River
reach (NMFS 2014). These diversions decrease the quantity of mainstem
flows on the Klamath River mostly during the spring and summer months,
when juvenile access to cooler tributaries and cooler mainstem water
temperatures is essential. Generally, spring and summer flows are lower
than historical conditions, while fall and winter flows in the Lower
Klamath are generally similar to those in the past.
Spring-run Chinook salmon continue to be limited in distribution
with the majority of the spawning in the mainstem Rogue River below
Lost Creek dam. The dam limits access to approximately one-third of
historical spring-run Chinook spawning habitat (ODFW 2007b). The
effects of the Lost Creek dam on gravel recruitment will be a recurring
problem, and it is not clear if gravel augmentation plans below Lost
Creek dam will successfully address the problem.
The SRT evaluated if the present or threatened destruction,
modification, or curtailment of the SONCC Chinook salmon ESU's habitat
or range is currently contributing to a risk of extinction or is likely
to contribute to a risk of extinction in the foreseeable future. In
evaluating habitat threats, the SRT concluded that current threats
(timber harvest, mining, dams and diversions, channelization, diking,
roads) presented low-to-moderate risks to the ESU. While there are some
concerns with habitat in the upper Rogue River mainly impacting spring-
run fish, the SRT concluded, and we agree, that it is unlikely that
this factor contributes significantly to a risk of rangewide extinction
now or in the foreseeable future. Factors leading to this conclusion
are dam removal on the Klamath River and the fish habitat management
strategies implemented at the dams in the Rogue River basin.
Additionally, the SRT noted that while there is a long history of land-
use practices leading to habitat degradation, freshwater habitat has
likely been improving slowly over the past several decades due to
habitat restoration projects and stricter land-use regulations compared
to the early 20th century. We anticipate the benefits of these efforts
will continue.
Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Tribal, commercial, and recreational salmon fisheries in the ocean
and fresh water harvest fish from the OC and SONCC Chinook salmon ESUs.
State and federal agencies use harvest restrictions to reduce impacts,
with the intent of ensuring enough adult fish return to spawn and
maintain healthy run sizes. However, ocean fisheries are inherently
mixed-stock, creating the potential for ocean harvest to
disproportionately affect weaker stocks. Across the West Coast, salmon
fisheries are managed to limit fishery impacts on certain low abundance
or protected stocks; this weak-stock management can result in
constraints on fisheries for abundant stocks that would not otherwise
be necessary (Pacific Fishery Management Council (PFMC) 2022).
OC Chinook Salmon ESU and Harvest
For OC stocks, the SRT examined two data sets: The Pacific Salmon
Commission Chinook Technical Committee's (CTC) Exploitation Rate
Analysis (ERA) and ODFW's terminal harvest rate estimates. The CTC's
ERA contains estimates of total exploitation rate (ocean and
freshwater) for Chinook salmon fisheries and stocks harvested within
the Pacific Salmon Treaty area (CTC 2023). The two southernmost stock
aggregates in the ERA (North Oregon Coast and Mid-Oregon Coast groups)
represent fall-run Chinook salmon arising from the OC Chinook salmon
ESU. In the North Oregon Coast aggregate, the ERA includes fall-run
Chinook salmon in the Nehalem, Salmon, Siletz, and Siuslaw rivers. In
the Mid-Oregon Coast aggregate, the ERA includes fall-run Chinook
salmon in the South Umpqua, Coquille, and Elk rivers. The ERA does not
estimate exploitation rates for spring-run Chinook salmon from the OC
Chinook salmon ESU.
The SRT analyzed the ERA data for fisheries mortality from 1979
through 2020 (SRT 2024). Despite substantial
[[Page 57004]]
inter-annual variation in exploitation rates of the North Oregon
stocks, there has been a modest decline in fisheries related mortality
since the early 1980s. Exploitation rates for the North Oregon stocks
have varied between 30 to 85 percent and averaged 52 percent over this
time period. There has also been a lot of inter-annual variation in the
Mid-Oregon stocks, but there appears to be a modest decline in
exploitation since the early 1980s. Exploitation rates for the Mid-
Oregon stocks have varied between 14 and 71 percent and averaged 43
percent over the same time period.
In addition to the CTC model, the SRT examined ODFW's terminal
harvest estimates for 12 coastal river basins (bay and freshwater
fisheries). ODFW's harvest rate estimates represent the number of fish
harvested as a proportion of the total run returning to each basin in a
given year. Among the 12 rivers, terminal exploitation rates vary from
60 percent (Tillamook) to 20 percent (Nehalem and Floras). Broadly
speaking, there appears to be an increasing trend in terminal
exploitation rates for the Nestucca, Siletz, Siuslaw, Umpqua, and Coos
stocks over the past several decades (1986-2021). We did not detect a
trend in terminal exploitation rates for the other river basins.
The Pacific Salmon Commission does not manage harvest of OC spring-
run Chinook salmon in the Pacific Salmon Treaty area. ODFW monitors
terminal harvest of spring-run Chinook salmon in the Umpqua River, but
not in ocean fisheries. Terminal harvest rates for Umpqua River spring-
run Chinook salmon has averaged 25 percent (2004-2019).
Several members of the SRT expressed concern over what they
considered to be high total exploitation rates (i.e., combined ocean
and terminal exploitation rates of 50 percent or more) of fall-run
Chinook salmon stocks. Whether or not exploitation rates greater than
50 percent are sustainable depends on the productivity of the stock.
Harvest rates above 50 percent can be sustainable if the stocks are
productive. The PFMC working group on Sacramento River Chinook salmon
has recently calculated exploitation rates corresponding to maximum
sustainable yield for 14 stocks of fall-run OC Chinook salmon and 2
stocks of spring-run OC Chinook salmon (PFMC Sacramento River Fall-run
Chinook Work Group (SRWG) unpublished) based on the published estimates
of spawner-recruit parameters for those stocks (Table A-II:11 in ODFW
2014b). The maximum sustainable yield is the largest long-term average
catch that can be taken from a stock under prevailing environmental and
fishery conditions. For all but one of the stocks (Elk River),
exploitation rates corresponding to maximum sustainable yield are
greater than 50 percent.
Based on the findings in PFMC SRWG (unpublished), we find that
current harvest rates are generally within the range of those expected
to produce maximum sustainable yield and overutilization is not
currently limiting the viability of the OC Chinook salmon ESU nor is it
likely to limit the viability in the foreseeable future.
SONCC Chinook Salmon ESU and Harvest
The PFMC manages ocean fisheries affecting the SONCC Chinook salmon
ESU under the Pacific Coast Salmon Fishery Management Plan (Salmon
FMP). The PFMC conducts annual stock assessments and fishery
evaluations under the Salmon FMP (PFMC 2022). These stock assessments
draw conclusions about the status of the stock (e.g., whether the stock
is overfished or approaching an overfished condition or whether
overfishing is occurring) in relation to the fishery management terms
defined under the Magnuson-Stevens Fishery Conservation and Management
Act (MSA) and/or NMFS' National Standards Guidelines, such as minimum
stock size threshold (MSST) and maximum fishing mortality threshold
(MFMT). The PFMC considers a stock to be overfished when the 3-year
geometric mean of escapement falls below MSST. The MFMT is the level of
annual fishing mortality above which overfishing is occurring. These
stock assessments, which provide information for determining the
sustainability of a fishery, are based on different criteria than those
under the ESA, which relate directly to the likelihood of extinction of
the species. In other words, an overfished status under MSA does not
necessarily correlate with a species' extinction risk. For example,
harvesting a salmonid stock at levels that make it subject to
overfishing and/or contribute to an overfished condition may not
necessarily pose a risk of extinction such that the species would
qualify for listing as an endangered or threatened species.
The Salmon FMP defines a Southern Oregon and Northern California
Chinook salmon stock complex that consists of natural and hatchery
stocks of spring- and fall-run Chinook salmon south of the Elk River,
Oregon, to (and including) the Klamath River, plus Umpqua River spring-
run Chinook salmon (PFMC 2024). The Salmon FMP defines three stocks
that overlap with the SONCC Chinook salmon ESU: Klamath River fall-run,
Smith River, and Southern Oregon Coast Chinook salmon. The Klamath
River fall-run Chinook salmon stock only partially overlaps with the
SONCC Chinook salmon ESU, since the stock consists of a small lower
Klamath River portion (part of the SONCC Chinook salmon ESU) and a
larger portion from the Upper Klamath/Trinity River Chinook salmon ESU.
The Salmon FMP does not include escapement goals or fishery impacts on
the Smith River. The Southern Oregon stock consists of spring- and
fall-run Chinook salmon south of the Elk River. The Salmon FMP includes
escapement goals for Rogue River fall-run Chinook salmon to track the
status of the Southern Oregon stock with respect to abundance. However,
the Salmon FMP does not include goals for fishery impacts on the stock.
The Salmon FMP defines an MFMT for Southern Oregon Coast Chinook
salmon of 78 percent, a species-specific proxy value derived from
twenty stock-recruitment data sets (covering brood years as early as
1946 and no later than 2000, though it varies widely by stock) for
stocks ranging from northern Washington to the Sacramento River basin.
In 2014, the Salmon Technical Team (STT 2014) and the Scientific and
Statistical Committee (SSC 2014) of the PFMC recommended adoption of a
stock-specific MFMT of 54 percent based on an analysis of Rogue River
fall-run Chinook salmon (Confer and Falcy 2014). The PFMC did not adopt
the recommendation, choosing instead to continue to use the proxy value
of 78 percent.
The PFMC assumes that age-specific harvest rates (the age of fish
caught by the fishery) of the Southern Oregon Chinook salmon stock are
equal to those estimated for the Klamath River Fall-run Chinook salmon
stock, but river harvest rates and age structure, and thus total
exploitation rates of southern Oregon Chinook salmon, are not tracked
by the PFMC (PFMC 2024). For the years 2013 through 2022, estimated
age-4 ocean harvest rates on the Klamath River Fall-run Chinook salmon
stock ranged from 4 to 38 percent (mean 22 percent). ODFW (unpublished
data) reports 2012-2021 terminal harvest rates on Rogue Fall-run
Chinook salmon of 4 to 28 percent with mean 12 percent and 2009-2018
river harvest rates of Rogue Spring-run Chinook salmon of 1 to 14
percent with mean 8 percent. In order to combine the ocean and terminal
harvest rates into a total exploitation rate we would need information
on maturation schedules (the probability of spawning if alive at a
given age). Because such information is not
[[Page 57005]]
available, we were unable to estimate the total exploitation rates for
Rogue River fall-run Chinook salmon. However, it seems unlikely that
exploitation rates would exceed the recommended MFMT of 54 percent, let
alone the MFMT of 78 percent defined in the Salmon FMP (PFMC 2024).
Terminal harvest rate estimates were higher on the Chetco River
(range of 8 to 37 percent with mean 18 percent) and Winchuck River (0
to 36 percent with mean 9 percent) during the same 10-year time period
(2012-2021). However, the mean terminal harvest rates for these stocks
are still likely to equate to total exploitation rates that are less
than the Rogue River Fall-run Chinook salmon MFMT, although this cannot
be determined with confidence without information on age structure and
maturation rates.
Given the available, albeit limited information for total
exploitation rate of stocks in the SONCC Chinook salmon ESU and the
fact that Rogue River Fall-run Chinook salmon have rarely fallen below
the MSST defined in the Salmon FMP, we found that overutilization is
not limiting the viability of the SONCC Chinook salmon ESU now nor is
it likely to limit the viability in the foreseeable future.
Disease
Chinook salmon are exposed to numerous bacterial, protozoan, viral,
and parasitic organisms in spawning and rearing areas, hatcheries,
migratory routes, and the marine environment. Increased physiological
stress and physical injury in migrating salmonids may increase their
susceptibility to pathogens (Matthews et al. 1986, Maule et al. 1988).
The presence of adequate water quantity and quality during late summer
is a critical factor in controlling disease epidemics for salmonids. As
water quantity and quality diminish, and freshwater habitat becomes
more degraded, many previously infected salmonid populations may
experience large mortalities because added physiological stress can
trigger the onset of disease. These factors (common in various rivers
and streams) may increase anadromous salmonid susceptibility and
exposure to disease (Holt et al. 1975, Wood and WDFW 1979).
OC Chinook Salmon ESU and Disease
Common diseases that affect Chinook salmon on the Oregon coast
include amoebic gill disease, bacterial cold-water disease, bacterial
kidney disease, columnaris, furunculosis, ich, and trichodiniasis. In
the Oregon Coastal Conservation and Management Plan (2014), ODFW
identified population-level factors that may be limiting the viability
of coastal Chinook salmon. ODFW (2014c) did not consider disease to be
a limiting factor for the OC Chinook salmon ESU. The SRT similarly
concluded that disease poses a low risk to the OC Chinook salmon ESU.
We conclude that disease poses a low risk to the viability of the OC
Chinook salmon.
SONCC Chinook Salmon ESU and Disease
ODFW (2007a, 2013) considered disease to be a primary factor that
affects the abundance of Chinook salmon in the Rogue River basin. ODFW
documented extensive mortalities of adult Chinook salmon in the
mainstem Rogue River in 1977, 1981, 1987, 1992, and 1994. Estimates of
mortality rates during those years ranged between 28 percent and 70
percent of the spring-run Chinook salmon that entered the Rogue River
(ODFW 2000). Columnaris was the disease most frequently identified in
dead and dying fall-run Chinook salmon sampled in the Rogue River
during the late 1970s and early 1980s (Amandi et al. 1982). Mortality
rates of juvenile Chinook salmon infected with F. columnare increase as
water temperature increases between 54 [deg]F and 70 [deg]F (Becker and
Fujihara 1978). Summertime water temperatures in the Rogue River can
approach the upper end of this range.
To minimize losses of adult and juvenile Chinook salmon to disease,
ODFW identified targets for maximum water temperature at the U.S.
Geological Survey gage near Agness, Oregon, and requested releases of
reservoir storage from Lost Creek Lake in order to meet water
temperature targets in downstream areas. Since 1995, the USACE has
directed the reservoir water release strategy toward using reservoir
storage to prevent, or to delay as long as possible, disease outbreaks.
The strategy appears to be working; no large disease outbreaks have
been documented in the Rogue River during the current multi-year
drought, nor during the recent ``heat dome'' event that occurred in
2021 (ODFW 2024).
The Klamath River has a history of myxosporean parasite infections,
including C. shasta and Parvicapsula minibicornis, which can
significantly impact survival of juvenile Chinook salmon. The highest
rates of infection in the Klamath River have been documented downstream
of Iron Gate Dam and are less likely to occur downstream of the Trinity
River confluence within the SONCC Chinook salmon ESU (Stocking and
Bartholomew 2007, Bartholomew and Foott 2010). Furthermore, the removal
of four dams (Iron Gate, Copco 1, Copco 2, and J.C. Boyle) on the upper
Klamath River should reduce the impacts of parasite infections
downstream (NMFS 2021).
Strategic water releases, dam removals, and other factors combined
have reduced the risk of disease for the SONCC Chinook Salmon ESU. The
SRT concluded that disease poses a low risk to the SONCC Chinook Salmon
ESU. We found no evidence to indicate otherwise, and conclude that
disease poses a low risk to the viability of the species.
Predation
A variety of species prey on juvenile and adult Chinook salmon.
Below we summarize the effects of predation separately for marine and
freshwater habitats.
Marine Predation
The Marine Mammal Protection Act (MMPA) of 1972 stopped the decline
of many marine mammal populations and led to the recovery of several in
the northeastern Pacific Ocean, such as populations of harbor seals,
Steller sea lions, and California sea lions. Studies indicate that
pinnipeds (seals and sea lions) prey on a wide variety of fish species,
and salmonids appear to be a minor part of their diet. Riemer and Brown
(1996) collected Steller sea lion scat (fecal) samples from the Rogue
Reef and Orford Reef breeding sites (Oregon) and identified salmonids
in 19.3 percent of samples. Riemer and Brown (1996) collected
California sea lion samples at the Cascade Head haul-out area near
Lincoln City, Oregon, and identified salmonids in 24.3 percent of
samples in February and 7.9 percent in October. Riemer et al. (2001)
collected scat samples from harbor seals in the Alsea and Rogue rivers
and found the frequency of occurrence of salmonids to range from 4.3 to
14.8 percent. Orr et al. (2004) found that harbor seals in the lower
Umpqua River consumed prey from over 35 taxa and found salmonid remains
in only 6 percent of samples. Lastly, Hillemeier (1999) assessed
pinniped predation rates within the Klamath River estuary during
August, September, and October 1997 and estimated that seals and sea
lions consumed a total of 8,809 adult fall-run Chinook salmon during
the study period (8.8 percent of the estimated fall-run Chinook salmon
run).
Fish-eating killer whales (Orcinus orca) consume a wide variety of
fish and squid, but salmon are their primary prey (Ford et al. 1998,
2000, Ford and Ellis 2006, Ford et al. 2016, Hanson et al. 2021). Scale
and tissue sampling from
[[Page 57006]]
May to September in inland waters of Washington and British Columbia,
Canada, indicate that fish-eating killer whale diets consist of a high
percentage of Chinook salmon (monthly proportions as high as 90
percent; Hanson et al. 2010). Ford et al. (2016) found that most of the
salmon consumed by the whales were Chinook salmon (nearly 80 percent).
Harbor seals, sea lions, and killer whales (including populations
in British Columbia and Alaska that feed on north-migrating salmon like
OC Chinook) have all increased at least three-fold over the past 50
years, and some studies suggest these increases have resulted in
proportional increases in predation pressures on salmon (SRT 2023).
Although the diets of seals and sea lions are diverse and salmon may be
a minor part of their diet, the overall increase in abundance of these
species, as well as resident killer whales, may have implications for
the long-term status of depleted, and in some cases ESA-listed,
salmonid populations. Chasco et al. (2017) estimated that, while
production of wild and hatchery Chinook salmon increased between 1975
and 2015 and harvest levels decreased, the increased consumption by sea
lions, harbor seals, and killer whales more than offset the first two.
Based on the model results, for stocks that have a longer and more
northerly migration route, such as those from the OC Chinook salmon
ESU, predation impacts have increased over time, exceeding harvest in
recent years (Chasco et al. 2017). The longer migration routes expose
these stocks to more predation by marine mammals.
Freshwater Predation
Kostow (1995) and ODFW (2014c) noted that a substantial smallmouth
bass population in the lower mainstem Umpqua River is of particular
concern. ODFW (2022) estimated that smallmouth bass were illegally
introduced into the Coquille River sometime prior to 2011. Since then,
the population of smallmouth bass has grown substantially and become
one of the primary factors limiting viability of the Coquille River
Chinook salmon population. ``Although wild fall-run Chinook [salmon] in
the Coquille suffered from poor ocean conditions, predation by
smallmouth bass is the primary reason these fish have not rebounded to
the same extent as in other coastal rivers'' (ODFW 2022). ODFW is
actively trying to remove smallmouth bass from the Coquille River to
reduce predation on juvenile wild fall-run Chinook salmon.
Umpqua pikeminnow were illegally introduced into the Rogue River in
the 1970s. Pikeminnow consume juvenile Chinook salmon and steelhead and
compete with native fishes for food and space. The estimated impact of
pikeminnow on the abundance of juvenile Chinook salmon in the Rogue
River basin is difficult to ascertain. Beamesderfer et al. (1996)
estimated that northern pikeminnow consumed about 16 million (8
percent) of the estimated 200 million juvenile salmonids emigrating
annually in the Columbia River Basin. The mainstem dams on the Columbia
River exacerbate predation opportunities. Umpqua pikeminnow predation
rates in the Rogue River are likely lower due to flow and temperature
management implemented at the William Jess and Applegate dams.
``Decreased water temperatures, resulting from reservoir releases
during summer, have likely limited the upstream distribution of Umpqua
pikeminnows in the Rogue River'' (ODFW 2013).
In addition, hatchery-produced coho salmon and steelhead consume
the fry of natural-origin spring-run Chinook salmon. Surveys from 1979
through 1981 estimated that the total annual number of spring-run
Chinook salmon fry consumed by hatchery coho salmon and steelhead was
between 163,000 and 275,000, representing 3-7 percent of Rogue River
spring-run Chinook salmon fry production during those years (ODFW
2007b). In addition to preying on natural-origin fish, large numbers of
hatchery fish can attract predators and increase predation rates on
natural-origin fish (Nickelson 2003, Weber and Fausch 2003, Nowak et
al. 2004). Hatchery programs attempt to limit predation impacts on
natural-origin salmonids through control of hatchery release numbers
and by minimizing spatial and temporal overlap with natural-origin
salmonid juveniles.
In summary, although the abundance of some marine mammals has
increased since the 1970s and the numbers of salmon have decreased, we
found no data to establish a cause-and-effect relationship. Anadromous
salmonids have historically coexisted with both marine and freshwater
predators. Studies focused on pinniped predation of OC and SONCC
salmonids suggest salmonids are a minor component of their diet. While
longer-ranging ESUs like OC Chinook are at greater risk of killer whale
predation, the available information led the SRT to conclude predation
is a low risk for both ESUs. Although introduced species appear to be a
leading cause for the decline of the Coquille River Chinook salmon
population, we found no evidence to indicate that freshwater predation
is a rangewide concern for the viability of the OC Chinook salmon ESU.
Similarly, the introduction of Umpqua pikeminnow into the Rogue River
basin does not appear to be a factor limiting the viability of either
spring-run or fall-run Chinook salmon populations in the SONCC Chinook
salmon ESU. Based on the available evidence and consistent with the
findings of the SRT, we conclude that predation poses a low risk to the
rangewide viability of the OC and SONCC Chinook salmon ESUs.
Inadequacy of Existing Regulatory Mechanisms
A variety of Federal, state, tribal, and local laws, regulations,
treaties and measures affect the abundance and survival of the OC and
SONCC Chinook salmon ESUs and the quality of their habitat. NMFS (1998)
found that the serious depletion of Chinook salmon and other anadromous
salmonids, coupled with the poor health and low abundance of many
distinct populations of Chinook salmon, was an indication that existing
regulatory mechanisms had largely failed to prevent the depletion. The
SRT reviewed existing regulatory mechanisms as part of the status
review. The SRT noted several Federal, state, and local regulatory
programs that have been successfully implemented to substantially
reduce historical risks to the OC and SONCC Chinook salmon ESUs. For
example, the U.S. Forest Service and Bureau of Land Management have
consulted with NMFS on land management plan amendments that include
adequate protection of riparian and stream habitat complexity for
salmon and steelhead (NMFS 2022). The states of Oregon and California
have amended or are in the process of amending their forest practices
and road management plans to address NMFS' concerns related to listed
OC and SONCC coho salmon. We expect that efforts designed to benefit
coho salmon will also benefit the co-occurring Chinook salmon.
Changes in regulations governing Chinook salmon fisheries have
significantly reduced the risks for Chinook salmon identified in the
coastwide status review (Myers et al. 1998) and status review update
(West Coast Chinook Salmon Biological Review Team 1999). For ocean
salmon fisheries on the West Coast, NOAA Fisheries works with the PFMC
to establish annual harvest levels in federal waters from 3 to 200
miles off the coasts of Washington, Oregon, and California. In
addition, adult salmon returning to Washington and Oregon migrate
through both U.S. and Canadian waters and are harvested by fishermen
[[Page 57007]]
from both countries. The U.S. and Canadian governments work with
tribes, states, and sport and commercial fishing groups to provide for
shared conservation and harvest objectives. These proceedings are
guided by the 1985 Pacific Salmon Treaty that is implemented through
the Pacific Salmon Commission.
The SRT concluded, and we agree, that the inadequacy of existing
regulatory mechanisms poses a low risk to the rangewide viability of
the OC and SONCC Chinook salmon ESUs. In the range of OC and SONCC
Chinook salmon, the regulation of some activities and land uses will
alter past harmful practices, resulting in habitat improvements.
Similarly, existing regulations governing Chinook salmon harvest have
improved the OC and SONCC ESUs likelihood of persistence.
Other Natural or Manmade Factors Affecting Its Continued Existence
Environmental Variation
Scientists predict the rising temperatures and associated ecosystem
changes caused by environmental variation to impact Pacific salmon by a
variety of mechanisms throughout their life cycle (Crozier et al. 2008,
2019, Isaak et al. 2022, Crozier and Siegel 2023). These impacts are
complex and vary among species, ESUs, and habitats. For U.S. West Coast
salmon and steelhead, expected changes to freshwater habitats include
increased air and stream temperatures and changes in seasonal (but not
necessarily annual mean) rainfall patterns, with larger and more
extreme storms and droughts. These increased temperatures will result
in more winter precipitation falling as rain than snow at intermediate
elevations, which alters both seasonal streamflow and water
temperatures. Within the range of the OC and SONCC ESUs, experts
predict stream temperatures to rise, winter flows to increase, and
summer flows to decrease compared to current patterns (ODFW 2021). In
marine habitats, we expect the food webs that support salmon to change
in response to factors including increased temperatures, acidification,
and the strength and timing of wind-driven upwelling, although how
these changes will affect salmon growth and survival is difficult to
predict.
Crozier et al. (2019) undertook a comprehensive climate
vulnerability assessment for Pacific salmon and steelhead along the
U.S. West Coast, focusing on ESUs that have received or are candidates
for protection under the ESA. Crozier et al. (2019) reported that
Chinook salmon populations ocean-type life histories (like OC and
SONCC) produced relatively low vulnerability scores during the early
life history and juvenile freshwater stages, due to limited rearing in
freshwater in summer, when thermal impacts, hydrologic regime shifts,
and low-flow impacts are expected to be highest. The OC and SONCC
Chinook salmon ESUs were not included in the Crozier et al. (2019)
assessment, so the SRT evaluated vulnerability to changing
environmental conditions using results for ESUs that had similar life
histories, geographic ranges, and human land use activities. For early
life history, estuary, and adult freshwater stages, the SRT used listed
Chinook salmon ESUs that had overlapping adult river entry timing
(spring and fall runs), fall spawn timing, limited freshwater residency
and extended estuarine residency, and predicted low-moderate
sensitivity for these attributes (early life history, estuary, and
adult freshwater stages) for the OC and SONCC Chinook salmon ESUs. For
the marine stage, OC Chinook salmon marine distributions extend from
local waters to SE Alaska and scored as a low-moderate sensitivity. In
contrast, the SONCC Chinook salmon marine distribution is largely
restricted to the California current and scored as moderate-high
sensitivity. The SRT ranked the cumulative life cycle effects for the
OC ESU as low-moderate vulnerability and for the SONCC ESU as moderate-
high. The estimated overall vulnerability rank is a measure of how
susceptible a particular ESU is to the impacts of environmental
variation and was estimated as moderate for OC and high for the SONCC
Chinook salmon ESUs.
However, the SRT also noted that there remains considerable
uncertainty about the localized effects of environmental variation on
these ESUs, and that predicted future stream temperatures in many of
the coastal streams should remain within suitable ranges for salmon.
For the OC and SONCC Chinook salmon ESUs, the predicted effects of
increasing temperatures may be greater for the rivers that are already
relatively warm during the summer, such as the Umpqua, Rogue, and
Coquille rivers, and less so for others, such as northern rivers of the
Oregon coast and the Smith River in California. The SRT (2024)
predicted portions of the spawning and rearing areas in some rivers,
including the Umpqua, Rogue, Nehalem, and Coquille to have average
August temperatures above 20[deg] C, a point at which salmon are
stressed physiologically and subject to greater disease pressures
(Richter and Kolmes 2005). However, these predictions are based on
average stream temperatures for relatively large river reaches and do
not account for potential small-scale thermal refuges that salmon may
use currently and in the foreseeable future. Isaak et al. (2022)
highlighted that Chinook salmon in the South Fork Umpqua River as
likely to be particularly vulnerable to warming temperatures, since it
already experiences near-lethal temperatures in some years and is
expected to become 1-3 [deg]F warmer by the end of century. Isaak et
al. (2022) concluded that other populations of OC and SONCC Chinook
salmon may be less impacted by warming temperatures due to a relatively
short juvenile freshwater life history. They also noted that the
regulation of water temperature by Lost Creek Dam is expected to
mitigate climate effects related to temperate and flow for portions of
the Upper Rogue River.
In marine habitats, the effects of sea level rise are largely
restricted to estuarine environments, but changes in sea surface
temperature, upwelling, currents, and ocean acidification, all of which
influence salmon productivity, are expected in estuarine and ocean
habitats. Crozier et al. (2019) reported that high levels of projected
changes in sea surface temperature and ocean acidification will be
compounded by regional variations in sea level rise, flooding, and
changes in upwelling. Crozier et al. (2019) noted that while coastal
areas may benefit from oceanic buffering effects that can reduce
extreme climate impacts, the complexity of marine food webs and
inconsistencies in projections for ocean currents and upwelling add
considerable uncertainty to predicting the full biological consequences
on salmon growth and survival. Prolonged periods of poor ocean survival
observed during warm decades suggest that rising ocean temperatures
could lead to negative impacts for salmon populations (Crozier et al.
2019).
Based on the SRT findings, we conclude that the effects of future
predicted environmental variation may pose a moderate risk to OC and
SONCC salmon ESUs. The SRT was particularly concerned that rising
stream temperatures and lower summer flows would be detrimental to the
spring-run life history, since adults spend some or all of the summer
in freshwater systems that are predicted to be exposed to higher
temperatures, and the spring runs are already at low abundance in most
of these rivers. Populations characterized by late-summer/early-fall
[[Page 57008]]
smolt outmigration may also be more vulnerable to temperature increases
than those with early-summer outmigration. The team also noted,
however, that there remains considerable uncertainty about the
localized effects of environmental variation to these populations, and
that predicted future stream temperatures in many of the coastal
streams remain within the healthy range for salmon.
Hatcheries
Hatcheries are another factor identified as a threat in the
coastwide Chinook salmon status review (Myers et al. 1998) and status
review update (West Coast Chinook Salmon Biological Review Team 1999).
Research on the risks and benefits of hatcheries to natural salmon
populations has been the subject of numerous reviews (e.g., Hard et al.
1992, Hatchery Scientific Review Group (HSRG) 2004, Mobrand et al.
2005, Araki et al. 2008, Naish et al. 2008, Kostow 2009, Anderson et
al. 2020). In general, hatchery programs can potentially provide
demographic benefits to salmon and steelhead, such as increases in
abundance during periods of low natural abundance (e.g., Berejikian et
al. 2009, Janowitz-Koch et al. 2019, Koch et al. 2022). Hatcheries may
also help preserve genetic resources until limiting factors can be
addressed (e.g., Flagg et al. 1995, Kalinowski et al. 2012). However,
these reviews have also concluded that long-term use of artificial
propagation poses risks to natural productivity and diversity. Hatchery
programs can affect natural-origin populations of salmon and steelhead
in a variety of ways, including competition (for spawning sites and
food) and predation effects, disease effects, genetic effects (e.g.,
domestication selection or introgression due to stock transfers), and
facility effects (e.g., water withdrawals, effluent discharge). The
magnitude and type of risk depend on the status of affected populations
and on specific practices in the hatchery program.
With the exception of the Elk and Salmon rivers, the fall-run
spawning populations in both ESUs consist primarily of natural-origin
spawners (SRT 2024). The situation with the spring-run populations is
more complex. Spring-run hatchery stocks released in the northern
portion of the OC Chinook salmon ESU likely originated from outside of
the ESU and pose genetic risks to native spring-run Chinook salmon that
spawn in the same rivers. In the southern portion of the OC Chinook
salmon ESU, the small South Fork Umpqua River spring-run population has
little hatchery influence, while the larger North Fork spring-run
spawning population typically consists of ~50 percent hatchery-origin
fish.
In the SONCC Chinook salmon ESU, ODFW operates the Cole Rivers
Hatchery on the Rogue River to mitigate the effects of Lost Creek Dam
and to provide fishing opportunities for spring-run Chinook salmon
(ODFW 2007b, 2016). ODFW founded the program from the local naturally
spawning population and reportedly uses ~27 percent natural-origin fish
in the broodstock annually (ODFW 2016, p. 31). ODFW estimates the
proportion of hatchery fish on the spawning grounds to be very low--
only 1.5 percent for the years 2016 and 2017 (ODFW 2007b). Based on the
local origin of the broodstock, the proportions of natural-origin fish
compared to hatchery-origin fish on the spawning grounds and in
broodstock, and the hatchery's potential as an important reservoir for
the run-type, the Cole River Hatchery program may be providing a net
conservation benefit to the SONCC Chinook salmon ESU.
Consistent with the above discussion, the SRT concluded, and we
agree, that hatcheries pose a low risk to the rangewide viability of
the OC and SONCC Chinook salmon ESUs.
Rangewide Risk of Extinction
The SRT's determination of rangewide extinction risk to the OC and
SONCC Chinook salmon ESUs used the categories of high, moderate, and
low risk of extinction. The risk levels are defined as:
(1) High risk: A species or ESU with a high risk of extinction is
at or near a level of abundance, productivity, diversity, and/or
spatial structure that places its continued existence in question. The
demographics of a species or ESU at such a high level of risk may be
highly uncertain and strongly influenced by stochastic and/or
depensatory processes. Similarly, a species or ESU may be at high risk
of extinction if it faces clear and present threats (e.g., confinement
to a small geographic area; imminent destruction, modification, or
curtailment of its habitat; disease epidemic) that are likely to create
such imminent demographic risks.
(2) Moderate risk: A species or ESU is at moderate risk of
extinction if it exhibits a trajectory indicating that it is more
likely than not to reach a high level of extinction risk in the
foreseeable future. A species or ESU may be at moderate risk of
extinction due to projected threats and/or declining trends in
abundance, productivity, spatial structure, or diversity. The
appropriate time horizon for evaluating whether a species or DPS is
more likely than not to become at high risk in the future depends on
various case- and species-specific factors. For example, the time
horizon may reflect certain life-history characteristics (e.g., long
generation time or late age-at-maturity) and may also reflect the
timeframe or rate over which identified threats are likely to impact
the biological status of the species or ESU (e.g., rate of disease
spread). The appropriate time horizon is not limited to the period that
status can be quantitatively modeled or predicted within predetermined
limits of statistical confidence.
(3) Low risk: A species or ESU is at low risk if it is not at
moderate or high risk of extinction.
The SRT considered the foreseeable future to extend over a time
period of 30 to 80 years. The shorter end of this time period
corresponds to approximately 10 Chinook salmon generations, which the
SRT concluded was a reasonable value over which to consider current
demographic trends. The most common age at spawning for the OC and
SONCC Chinook salmon ESUs is 3 to 4 years of age (ODFW 2007a, 2013,
2014a). The longer end of this range corresponds approximately to the
timeframe over which scientific studies of the impacts of environmental
variation on salmon freshwater and ocean habitat are available. For
example, the SRT cited and utilized analyses of predicted future stream
temperatures (Isaak et al. 2017 and 2022) that ranged from
approximately 40 to 80 years in the future.
OC Chinook Salmon ESU
The SRT concluded, and we concur, that the OC Chinook salmon ESU is
at low risk of extinction. The primary factors leading to this
conclusion include relatively high total abundance, with multiple
populations having natural-origin spawning abundance of >10,000
spawners in typical years, and total-ESU abundance commonly >100,000
spawners. The high total exploitation rates (often exceeding 50 percent
for most populations), although a source of some concern, are also
evidence of relatively high productivity, because the populations are
(generally) maintaining their abundance despite higher harvest rates.
An analysis of the spatial structure and diversity factors also
indicate low risk. The ESU consists of numerous, well-distributed
spawning populations, indicating that there is low risk associated with
spatial structure. The presence of spring- and summer-run fish
distributed throughout many of the basins indicates that the ESU as a
whole contains considerable life-history
[[Page 57009]]
diversity. There is some concern over the potential effects of the
long-term, segregated hatchery programs in the Trask and Nestucca
rivers. However, because there is relatively limited hatchery
production rangewide (when compared to natural production), we conclude
that hatcheries pose a low risk to the rangewide diversity of the ESU.
In our evaluation of the factors identified in section 4(a)(1) of
the ESA, we find that the factors do not contribute to rangewide
extinction risk now or in the foreseeable future. There is a long
history of land-use practices leading to habitat degradation, but
freshwater habitat appears to be improving due to restoration efforts
and stricter land-use regulations compared to the 20th century (see OC
Chinook salmon and Habitat and Inadequacy of Existing Regulatory
Mechanisms). The SRT identified predation by nonnative small-mouth bass
as a factor limiting the viability of the Coquille River population,
but otherwise predation by nonnative species poses a low risk to the
ESU rangewide. Although ODFW (2014a) identified predation by marine
mammals as a matter of public interest, we found no evidence to
indicate that it poses a risk to the viability of the species. Although
some SRT members were concerned about exploitation rates that
occasionally exceed 50 percent for some populations, we find that
fishery management has responded to changes in status of individual
populations and reduced exploitation rates as necessary, particularly
for terminal fisheries.
The SRT concluded, and we concur, that the predicted effects of
environmental variation will likely have a negative effect on the OC
Chinook salmon ESU. The SRT was particularly concerned that rising
stream temperatures and lower summer flows would be detrimental to the
spring-run life history, since adults spend some or all of the summer
in freshwater systems that are predicted to be exposed to higher
temperatures, and the spring runs are already at low abundance in most
of these rivers. Populations characterized by late-summer/early-fall
smolt outmigration may also be more vulnerable than those with early-
summer outmigration. The SRT also considered environmental variation
effects on marine ecosystems and concluded that the OC Chinook salmon
ESU is predicted to have a moderate sensitivity to marine climate
effects but noted the complexity of ocean food webs and their response
to changing conditions, as well as the indirect nature of impacts
through prey availability and predator distribution, make direct
predictions of salmon survival difficult. However, the SRT noted that
the ESU consists of 16 major populations and additional smaller ones
that are distributed among multiple coastal streams, many of which are
predicted to remain at appropriate temperatures for salmon even in the
face of environmental variation. Thus, although the SRT concluded that
portions of the ESU will be negatively impacted by changing
environmental conditions, the ESU as a whole is likely buffered against
these predicted changes for the foreseeable future.
Considering the analysis of the viability of the ESU and the
factors identified in section 4(a)(1) of the ESA, we find that the OC
Chinook salmon ESU is at a low risk of extinction rangewide, now and in
the foreseeable future.
SONCC Chinook Salmon ESU
The SRT concluded, and we concur, that the SONCC Chinook salmon ESU
is at low risk of extinction rangewide. Factors supporting this
conclusion include overall high abundance, which has been commonly
>50,000 natural spawners for the ESU as a whole (not including the
Smith River), most of which consist of natural-origin fish. The ESU
also appears to have high productivity, as indicated by the fact that
the ESU has maintained high abundance levels in the presence of
relatively high total exploitation rates. The ESU consists of numerous,
well-distributed spawning populations, indicating that there is low
risk associated with spatial structure. Although there are concerns
about the status of the spring-run component of the ESU (discussed
below), the spring-run life history nonetheless comprises several
thousand spawners annually in the Rogue River, as well as a much
smaller number of spring-run Chinook salmon spawners in the Smith
River. The fall-run component is spatially spread across multiple
populations, most of which typically have natural spawning abundance in
the thousands.
In our evaluation of the factors identified in section 4(a)(1) of
the ESA, we find that the factors do not contribute substantially to
rangewide extinction risk now or in the foreseeable future. Although
habitat loss and the ongoing effects of land management activities
continue to be a concern, freshwater habitat appears to be improving
due to habitat restoration activities and stricter land-use regulations
compared to the 20th century (see SONCC Chinook salmon and Habitat and
Inadequacy of Existing Regulatory Mechanisms). Since the previous
status review a number of actions have been taken to restore or improve
fish passage, riparian conditions, and instream habitat in the coastal
basins of southern Oregon and northern California (OWEB 2024, CalFish
2024). As a result, habitat utilization has improved for Chinook salmon
since the late 1990s. Although some members of the SRT were concerned
about harvest rates, overall abundance remains high, and we found no
evidence to indicate that overutilization is limiting the viability of
the SONCC Chinook salmon ESU now or in the foreseeable future.
The SRT concluded, and we concur, that the predicted effects of
environmental variation will likely have a negative effect on the SONCC
Chinook salmon ESU, particularly for the spring-run life history whose
habitat may be differentially vulnerable to high temperatures, lower
summer flows, and the effects of increasing wildfires and associated
disturbances. Populations characterized by late-summer/early-fall smolt
outmigration may also be more vulnerable than those with early-summer
outmigration. The SRT also considered the effect of environmental
variation on marine ecosystems and ranked SONCC ESU with a moderate
sensitivity score in their marine stage, but the team also noted the
complexity of ocean food webs and their response to changing
environmental conditions, as well as the indirect nature of impacts
through prey availability and predator distribution, which makes direct
predictions of salmon survival difficult. The SRT noted that the ESU
consists of at least eight major populations and additional smaller
ones that are distributed among multiple coastal streams, many of which
are predicted to remain at appropriate temperatures for salmon even in
the face of future environmental variation. Thus, although the SRT
concluded that portions of the ESU will be negatively impacted by
changing environmental conditions, the ESU as a whole is likely
buffered against these predicted changes for the foreseeable future.
Considering the analysis of the viability of the ESU and the
factors identified in section 4(a)(1) of the ESA, we find that the
SONCC Chinook salmon ESU is at a low risk of extinction rangewide, now
and in the foreseeable future.
Significant Portion of Its Range Analysis
As noted in the introduction above, the definitions in section 3 of
the ESA of both ``threatened species'' and ``endangered species''
contain the term ``significant portion of its range'' (SPR),
[[Page 57010]]
which we interpret to refer to an area smaller than the entire range of
the species. As indicated by these definitions, we can list a species
based on their status in all of their range or based on their status in
a SPR. The range of a species is considered to be the general
geographical area within which that species can be found. A species'
range includes those areas used throughout all or part of the species'
life cycle, even if they are not used regularly (e.g., seasonal
habitats) (79 FR 37578, 37583, July 1, 2014).
In construing the statutory definitions of threatened and
endangered species, we are required to give some independent meaning to
the SPR phrase to avoid rendering it superfluous to the ``throughout
all'' language (See Defenders of Wildlife v. Norton, 258 F.3d 1136 (9th
Cir. 2001)). Under the 2014 policy regarding the interpretation of the
phrase ``significant portion of its range'' (SPR Policy; 79 FR 37578,
July 1, 2014), which was issued jointly by NMFS and USFWS, if we find
that a species is facing low extinction risk throughout its range
(i.e., not warranted for listing), we must consider whether the species
may have a higher risk of extinction in a SPR (79 FR 37578, July 1,
2014). In addition, if we find that a species is threatened rangewide,
we must also consider whether the species may be endangered in an SPR,
which would result in the higher-level listing of the species as
endangered (See CBD v. Everson, 435 F. Supp. 3d 69 (D.D.C. 2020)).
Having concluded that the OC Chinook salmon and SONCC Chinook
salmon ESUs are at low risk of extinction now and in the foreseeable
future throughout all of their respective ranges, we requested the SRT
conduct an assessment to determine whether the ESUs may be at greater
risk of extinction now or in the foreseeable future in any identified
SPR. The SRT's SPR analysis consisted of identifying and evaluating
portions, also described as strata, of each ESU that are potentially at
moderate or high risk of extinction and are important to the overall
ESU's long-term viability, yet not so important as to be determinative
of its overall current or foreseeable status. In other words, the goal
of the SPR evaluation was to determine if there are biologically
important portions of the ESU that are currently at high or moderate
risk but that are not so important that their status would lead to the
entire ESU being currently at high or moderate risk.
Because a species' range can theoretically be divided into an
infinite number of portions, the SRT first discussed and identified
several sub-ESU strata that had a reasonable likelihood of being at
moderate or high risk of extinction and a reasonable likelihood of
being biologically significant to the species. Unless a portion met
both of these conditions, the SRT did not consider it further in the
analysis as they could not form the basis for a proposed listing. In
evaluating whether a portion was biologically significant, the SRT
considered whether the species within that portion was important to the
ESU's long-term viability but not so important that their status would
drive current or foreseeable ESU-wide extinction risk. After
considering multiple possibilities, the SRT settled on a more detailed
evaluation of two types of strata based on geography or adult run-
timing.
OC Chinook Salmon ESU
In the geographic SPR analysis, the SRT divided the OC Chinook
salmon ESU into four geographic strata: North Coast, Mid-Coast, Umpqua,
and Mid-South Coast. The North Coast stratum is composed of populations
of Chinook salmon from the Necanicum River south to the Nestucca River
(inclusive). The Mid-Coast stratum is composed of populations of
Chinook salmon from the Salmon River south to the Siuslaw River
(inclusive). The Umpqua stratum is composed of the Chinook salmon
populations in the Umpqua River basin. The Mid-South Coast stratum is
composed of populations of Chinook salmon from the Tenmile basin south
to the Elk River. In Oregon's Coastal Multi-Species Conservation and
Management Plan, ODFW divides the OC Chinook salmon ESU into these same
four geographic strata (ODFW 2014a).
The SRT evaluated the extinction risk for each stratum. The SRT
concluded, with varying degrees of confidence, that all four strata
were most likely to be at low risk of extinction. The SRT was less
confident that the Mid-South Coast stratum was at low risk based on
concerns that the southern populations included generally lower and
recently declining abundance, especially a sharp recent decline of the
Coquille River population (2007-2021). The SRT noted that the Mid-South
Coast stratum contains four populations other than the Coquille
population with a combined total of several thousand spawners, and,
despite recent trends, the populations have largely been stable over
the last 35 years leading to the low-risk conclusion. The SRT also
noted that each of the four strata had at least one, and usually
several, populations that the SRT considered to be abundant,
productive, and at low risk of extinction. We evaluated the SRT's
findings and concluded that the findings are well-supported and that
all four strata are a low risk of extinction now and in the foreseeable
future, so we did not assess the geographic strata further.
The SRT also considered whether the variation in adult run-timing
might form the basis for identifying alternative portions. In many
river systems along the West Coast, spring- and fall-run Chinook salmon
utilize spatially different freshwater habitats, particularly during
the adult freshwater migration and spawning portions of the life cycle.
While there is evidence of some spatial segregation between the spring-
and fall-run timing components in the Umpqua River basin (ODFW 2014a)
and Siletz River basin (Davis et al. 2017), the relatively small size
of other OC basins limits the amount of habitat available and minimizes
the likelihood of spatial separation of run times (Myers et al. 1998).
For OC basins utilized by spring-run Chinook salmon, spring-run-only
habitat constitutes 4 percent of the available spawning and rearing
habitat. In other words, 96 percent of the spring-run geography is
shared with the fall-run fish. Given the substantial overlap in spring-
and fall-run habitat, we have determined the spring-run stratum does
not qualify as a valid portion of the OC Chinook salmon range.
Consistent with the ESA, the 2014 SPR Policy defines ``range'' in
geographic terms, and the selection of portions for consideration
should be premised at least in part on a geographically oriented
rationale. Although run timing might provide an appropriate basis for
delineating portions under certain circumstances, here, the spring-run
component lacks sufficient spatial segregation from the fall run to be
considered a valid portion for the purposes of SPR analysis under the
ESA. Additionally, the SRT concluded that the spring-run component of
the OC Chinook salmon ESU was not biologically significant to the long-
term viability of the ESU. Factors leading to this conclusion included
the lack of spring-run specific habitat in most of the river systems in
the ESU and the lack of strong evidence that the spring run was ever
historically a substantial component of the ESU. Therefore, we
determined the spring-run component does not qualify as a valid portion
of the OC Chinook salmon range.
The fall-run component is the most numerous and widespread portion
of the ESU. The status of the fall-run component is determinative of
the rangewide status of the ESU and also considered to be at low
extinction risk.
[[Page 57011]]
Therefore, the fall-run component is not a valid SPR.
We did not identify any other valid portions that were both
significant and at a higher extinction risk than the ESU rangewide, now
or in the foreseeable future. Based on the above, we conclude that
Chinook salmon in the OC ESU are not presently in danger of extinction
nor are they likely to become endangered in the foreseeable future.
SONCC Chinook Salmon ESU
The SRT identified two geographic strata within the SONCC Chinook
salmon ESU: a Rogue River stratum and a coastal river system (Hunter,
Pistol, Chetco, Winchuck, Smith, and Lower Klamath rivers) stratum. For
the Rogue River stratum, the SRT concluded that it was at low risk
based on consistently high overall abundance, including thousands of
spring-run spawners and fall-run populations spatially distributed
across multiple populations despite significant harvest pressure. For
the coastal stratum, the SRT narrowly concluded that it is at moderate
risk based on relatively small sizes and small number of coastal
populations and a lack of consistent monitoring for the important Smith
River population. However, the relatively small size of SONCC coastal
basins limits the amount of available habitat, so small number and
sizes of coastal populations do not necessarily mean the coastal
populations are at a higher risk of extinction. Though the coastal
populations are smaller than the Rogue River, recent abundances for the
combined Hunter, Pistol, Chetco, Winchuck, and Blue River populations
total a few thousand spawners annually. Furthermore, estimates for the
Smith River from 2010 to 2021 were between 10,000 and 20,000 fall-run
Chinook salmon, suggesting that it is likely the second-largest
population in the SONCC ESU. The lack of adequate monitoring for the
Smith River was also a primary concern that led the team to conclude
the coastal stratum was at moderate risk, which indicates that the
uncertainty from the lack of monitoring shifted the team towards a
higher risk category for this geographic area. However, the absence of
monitoring or data does not directly cause a species to decline or face
extinction and does not in and of itself support a positive listing
determination. While monitoring data are limited, the available data do
suggest the Smith River contains a sizeable fall run as noted above.
Additionally, the threats to these populations are similar to the
threats facing the entire ESU, so the stratum does not face an elevated
extinction risk. Based on the coastal population sizes (including the
Smith River), spatial distribution, and similar threats across the ESU,
we determined that the SONCC coastal stratum is at low risk of
extinction now and in the foreseeable future.
We have determined the spring-run stratum does not qualify as a
valid portion of the SONCC Chinook salmon range because, consistent
with the ESA and the 2014 SPR Policy (79 FR 37578, 37583 July 1, 2014),
the selection of portions for consideration should be premised at least
in part on a geographically oriented rationale. Here, the spring-run
component lacks sufficient spatial segregation from the fall run to be
considered a valid portion of the ESU's range for the purposes of SPR
analysis under the ESA. While there is evidence of spatial segregation
between the spring- and fall-run timing components in the Rogue River,
the relatively small size of other SONCC basins limits the amount of
habitat available and minimizes the likelihood of spatial separation of
run times. A review of spawning and rearing habitat utilized by spring-
run Chinook salmon, mainly found in the Rogue River and Smith River
basins, found only 6 percent of the habitat was used solely by spring-
run Chinook salmon. In other words, 94 percent of spring-run geography
is shared with fall-run fish. Therefore, the spring-run component does
not qualify as a valid portion of the SONCC Chinook range.
Spring-run Chinook salmon was narrowly voted by the SRT to have a
higher risk than the ESU rangewide, but given that spring-run
populations do not reflect a sufficiently unique geographic area from
fall-run populations, the spring-run portion cannot be considered a
SPR. The fall-run component is the most numerous and widespread portion
of the ESU. The status of the fall-run component is determinative of
the rangewide status of the ESU and also considered to be at low
extinction risk. Therefore, the fall-run component of the SONCC ESU is
not a valid SPR.
We did not identify any other valid portions that were both
significant and at a higher level of extinction risk than the ESU
rangewide, now or in the foreseeable future. Based on the above, we
conclude that SONCC Chinook salmon ESU is at low risk of extinction
throughout its range and is not presently in danger of extinction nor
is it likely to become endangered in the foreseeable future.
Final Determination
Section 4(b)(1) of the ESA requires that we make listing
determinations based solely on the best scientific and commercial data
available after conducting a review of the status of the species and
taking into account those efforts, if any, being made by any State or
foreign nation, or political subdivisions thereof, to protect and
conserve the species. We have independently reviewed the best available
scientific and commercial information, including references cited in
the petition, public comments submitted on the 90-day finding (88 FR
1548, January 11, 2023), and the status review report, and we have
consulted with species experts and individuals familiar with Chinook
salmon.
Our determination set forth here is based on a synthesis and
integration of the foregoing information. Based on our consideration of
the best available scientific and commercial information, as summarized
here and in the status review report, we conclude that Chinook salmon
in the OC and SONCC ESUs, inclusive of all run types, are not presently
in danger of extinction nor are they likely to become endangered in the
foreseeable future throughout all or a significant portion of their
range. Consequently, the OC and SONCC ESUs do not warrant listing under
the ESA.
This is a final action, and, therefore, we are not soliciting
public comments.
References
A complete list of all references cited herein is available upon
request (See FOR FURTHER INFORMATION CONTACT).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: December 4, 2025.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2025-22335 Filed 12-8-25; 8:45 am]
BILLING CODE 3510-22-P
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