[Federal Register Volume 85, Number 24 (Wednesday, February 5, 2020)]
[Notices]
[Pages 6527-6531]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-02174]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[Docket No. 200130-0037; RTID 0648-XG758]


Listing Endangered and Threatened Wildlife and Plants; Notice of 
12-Month Finding on a Petition To List Summer-Run Steelhead in Northern 
California as Endangered 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.

-----------------------------------------------------------------------

SUMMARY: We, NMFS, announce a 12-month finding on a petition to 
delineate Northern California (NC) summer-run steelhead as a distinct 
population segment (DPS) of West Coast steelhead (Oncorhynchus mykiss), 
and to list that DPS as endangered under the Endangered Species Act 
(ESA). We have completed a comprehensive DPS analysis of NC summer-run 
steelhead in response to the petition. Based on the best scientific and 
commercial data available, including the DPS configuration review 
report, we have determined that listing NC summer-run steelhead as an 
endangered DPS is not warranted. We determined that summer-run 
steelhead in the NC steelhead DPS do not meet the criteria to be 
considered a DPS separate from winter-run steelhead. We also announce 
the availability of the DPS configuration review report prepared 
pursuant to the ESA for the NC steelhead DPS.

DATES: This finding was made on February 5, 2020.

ADDRESSES: The documents informing the 12-month finding, including the 
DPS configuration report (Pearse et al. 2019), are available by 
submitting a request to the Assistant Regional Administrator, Protected 
Resources Division, West Coast Regional Office, 501 W Ocean Blvd., 
Suite 4200, Long Beach, CA 90802, Attention: NC Summer-run Steelhead 
12-month Finding. The documents are also available electronically at 
https://www.fisheries.noaa.gov/region/west-coast.

FOR FURTHER INFORMATION CONTACT: Gary Rule, NMFS West Coast Region at 
[email protected], (503) 230-5424; or Heather Austin, NMFS Office of 
Protected Resources at [email protected], (301) 427-8422.

SUPPLEMENTARY INFORMATION: 

Background

    On November 15, 2018, the Secretary of Commerce received a petition 
from the Friends of the Eel River (hereafter, the Petitioner) to list 
NC summer-run steelhead as an endangered DPS under the ESA. Currently, 
NC summer-run steelhead are part of the NC steelhead DPS that combines 
winter-run and summer-run steelhead and is listed as threatened under 
the ESA (71 FR 833; January 5, 2006). The Petitioner is requesting that 
NC summer-run steelhead be considered as a separate DPS and listed as 
endangered. On April 22, 2019, we published a positive 90-day finding 
(84 FR 16632) announcing that the petition presented substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted. In our 90-day finding, we also announced the 
initiation of a status review of the NC summer-run steelhead and 
requested information to inform our decision on whether the species 
warrants listing as threatened or endangered under the ESA.

Listing Species Under the ESA

    We are responsible for determining whether species under our 
jurisdiction are 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 (16 
U.S.C. 1532), and then, if so, consider 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 DPS of any species of vertebrate fish or 
wildlife which interbreeds when mature. On February 7, 1996, NMFS and 
the U.S. Fish and Wildlife Service (USFWS; together, the Services) 
adopted the Policy Regarding the Recognition of Distinct Vertebrate 
Population Segments Under the Endangered Species Act, a policy 
describing what constitutes a DPS of a taxonomic species (DPS Policy; 
61 FR 4722). Under the DPS Policy, we consider the following when 
identifying a DPS: (1) The discreteness of the population segment in 
relation to the remainder of the species or subspecies to which it 
belongs; and (2) the significance of the population segment to the 
species or subspecies to which it belongs.
    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. 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. In other words, the primary statutory 
difference between a threatened and endangered species is the timing of 
when a species may be in danger of extinction, either presently 
(endangered) or in the foreseeable future (threatened).
    Section 4(a)(1) of the ESA also requires us to determine whether 
any species is endangered or threatened as a result of any of the 
following five 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 
(16 U.S.C. 1533(a)(1)(A)-(E)). Section 4(b)(1)(A) of the ESA requires 
us to make listing determinations based solely on the best scientific 
and commercial data available after conducting a review of the status 
of the species and after taking into account efforts being made by any 
state or foreign nation or political subdivision thereof to protect the 
species. In evaluating the efficacy of formalized domestic conservation 
efforts that have yet to be implemented or demonstrate effectiveness, 
we rely on the Services' joint Policy on Evaluation of Conservation 
Efforts When Making Listing Decisions (PECE; 68 FR 15100; March 28, 
2003).

[[Page 6528]]

Status Review

    As part of our review of the Petitioner's request to delineate a NC 
summer-run steelhead DPS and list it as endangered under the ESA, we 
formed an expert panel (Panel) consisting of scientists from NMFS 
Southwest Fisheries Science Center (SWFSC) and Northwest Fisheries 
Science Center (NWFSC). We asked the Panel to provide: (1) An analysis 
and review of the petitioners' claim that NC summer-run steelhead 
should be considered a separate DPS; and, if so, (2) a description of 
the demographic risks (i.e., abundance, productivity, spatial 
distribution and diversity) of any new DPSs identified. The first task 
was for the Panel to compile the best available scientific and 
commercial information relevant to evaluating the DPS structure of 
summer-run steelhead in northern California, including information 
presented by the petitioners. Specifically the NMFS West Coast Region 
(WCR) requested the Panel address the criteria in the DPS Policy (61 FR 
4722; February 7, 1996). Completion of the second task depended on the 
Panel's finding and the WCR's concurrence with their finding in the 
first task. If the Panel concluded that summer-run steelhead should be 
considered a separate DPS, and the WCR concurred, the Panel would 
complete the second task and submit their report on both tasks to the 
WCR. If the Panel concluded, and WCR concurred, that there should not 
be a change in the current DPS structure (i.e., the summer-run 
steelhead are part of the NC steelhead DPS), the Panel would finalize 
their DPS structure findings and submit a report to the WCR. Under this 
second scenario, review of the viability of the NC steelhead DPS would 
be assessed in 2020 as part of the coast-wide five-year assessment.
    In order to complete their DPS analysis, the Panel considered a 
variety of scientific information from the literature, unpublished 
documents, and direct communications with researchers working on the 
genetics of steelhead, as well as technical information submitted to 
NMFS. Information that was not previously peer-reviewed was formally 
reviewed by the Panel. Only the best-available science was considered 
further. The Panel evaluated all factors highlighted by the petitioners 
as well as additional factors that may contribute to our understanding 
of the evolutionary significance of run-timing in steelhead.
    Following an evaluation of the two DPS criteria, the Panel arrived 
at a final conclusion regarding the DPS configuration using a voting 
method. Each of the four Panel members were given 10 votes to apportion 
between the two DPS configurations: (1) Summer-run and winter-run 
steelhead should remain together in a single NC steelhead DPS; or (2) 
summer-run and winter-run steelhead in Northern California should be 
separated into two DPSs.
    The Panel's draft report was subjected to independent peer review 
as required by the Office of Management and Budget (OMB) Final 
Information Quality Bulletin for Peer Review (M-05-03; December 16, 
2004). The draft report was peer reviewed by an independent specialist 
selected from the academic and scientific community, with expertise in 
the genetic diversity of salmonids, as well as biology, conservation, 
and management. The peer reviewer was asked to evaluate the adequacy, 
appropriateness, and application of data used in the report. All peer 
reviewer comments were addressed prior to dissemination and 
finalization of the draft report and publication of this finding.
    We subsequently reviewed the report, its cited references, and peer 
review comments, and believe the report, upon which this 12-month 
finding is based, provides the best available scientific and commercial 
information on the NC steelhead DPS. Much of the information discussed 
below is attributable to the report. In making the 12-month finding, we 
have applied the statutory provisions of the ESA; this includes an 
evaluation of the application of the factors set forth in section 
4(a)(1)(A)-(E); our regulations regarding listing determinations (50 
CFR part 424); and the DPS Policy (61 FR 4722; February 7, 1996).

Northern California Steelhead

    On June 7, 2000, using the Policy on Applying the Definition of 
Species under the Endangered Species Act to Pacific Salmon (56 FR 
58612; November 20, 1991) (Evolutionarily Significant Unit (ESU) 
Policy), NMFS listed the NC steelhead ESU as a threatened species (65 
FR 36074). In the final listing determination, we concluded that in 
certain situations the ESU consisted of both anadromous and resident 
life forms of O. mykiss. We listed the anadromous portion of the ESU, 
which was under our jurisdiction. A court ruling in 2001 (Alsea Valley 
Alliance v. Evans, 161 F. Supp. 2d 1154 (D. Or. 2001)) determined that 
listing only a subset of a species or ESU/DPS, such as the anadromous 
portion of O. mykiss, was not allowed under the ESA. Because of this 
court ruling, NMFS conducted updated status reviews for all West Coast 
steelhead ESUs that took into account those non-anadromous individuals 
below dams and other major migration barriers that were considered to 
be part of the steelhead ESUs (Good et al., 2005). Subsequently, NMFS 
decided that the joint USFWS-NMFS DPS Policy was more appropriate for 
steelhead listing decisions than the ESU Policy, which was specifically 
designed for Pacific salmon. Using the DPS Policy, NMFS redefined the 
NC steelhead ESU as a steelhead-only DPS and reaffirmed that the NC 
steelhead DPS was a threatened species under the ESA (71 FR 834; 
January 5, 2006). The DPS includes both summer-run and winter-run 
steelhead. Since 2006, NMFS has conducted two status reviews (76 FR 
50447; August 15, 2011 and 81 FR 33468; May 26, 2016) to evaluate 
whether the listing classification of NC steelhead remains accurate or 
should be changed. In both instances, after reviewing the best 
available scientific and commercial data, we concluded that no change 
in ESA-listing status for NC steelhead was warranted.
    The NC steelhead DPS extends from Redwood Creek (Humboldt County) 
in the north, southward to, but not including, the Russian River. 
Within this region, the Eel River is the largest watershed, with 
numerous tributaries that contain significant spawning habitat for 
steelhead. Importantly, the DPS contains populations of both the more 
widespread winter-run life history type and scattered populations with 
the summer-run life history type, the largest of which is in the Middle 
Fork of the Eel River. The timing of river entry varies considerably 
among populations and run-types, both across the species range and 
within California (Busby et al. 1996). For California populations, 
summer-run steelhead typically enter freshwater in the spring or early 
summer (approximately March through June or July); however, these fish 
do not spawn until the following fall, winter, or spring. In contrast, 
winter-run steelhead enter freshwater at any time from the late summer 
through the following spring, and spawn sometime during that same 
period (Shapovalov and Taft 1954; Puckett 1975; Busby et al. 1996).
    Extant and historical summer- and winter-run steelhead populations 
in the Northern California DPS were identified by Bjorkstedt et al. 
(2005). Within the NC steelhead DPS area, winter-run are widely 
distributed across the landscape, but summer-run steelhead have very 
specific habitat requirements for parts of their life history, 
primarily the need for access to large pools with cool water in which 
they remain during the summer holding period (Nakamoto 1994; Nielsen

[[Page 6529]]

et al. 1994). Puckett (1975) identified potential natural migrational 
barriers in the Middle Fork Eel River and Van Duzen River that provided 
some degree of separation between summer-run and winter-run steelhead 
spawning habitat, and recommended against removing migration barriers 
because it would likely result in increased mixing of the two run 
types. In the Mad River, a natural barrier apparently separating 
summer- and winter-run steelhead was identified by Knutson (1975) near 
Bug Creek. Roelofs (1983) suggested that summer-run spawning habitat is 
often characterized by limited accessibility, ``ruggedness,'' and 
intermittent flow. Thus, a combination of factors influencing river 
geomorphology and hydrology (e.g., precipitation, stream gradient, 
geology, etc.) likely limit the distribution of summer-run steelhead, 
but may be highly variable among years such that complete reproductive 
isolation is unlikely even in the presence of a strongly flow-dependent 
migration barrier.
    In the most recent five-year status review (NMFS 2016a; Williams et 
al. 2016), data on summer-run steelhead populations were available for 
Redwood Creek, Mad River, Van Duzen River, Middle Fork Eel River, and 
Mattole River. Additional potential populations for which little 
information was available included Larabee Creek, North Fork Eel River, 
and South Fork Eel River (Williams et al. 2016). Although both life-
history types were likely to have been negatively impacted by the 
recent drought in California, Williams et al. (2016) concluded that 
there was ``no strong evidence to indicate conditions for winter-run 
populations in the DPS have worsened appreciably since the last status 
review (Williams et al. 2011).'' However, they also noted that 
``Summer-run populations continue to be of significant concern. The 
Middle Fork Eel River population has remained remarkably stable for 
nearly five decades and is closer to its viability target than any 
other population in the DPS. Although the time series is short, the Van 
Duzen River and Mad River appear to be supporting populations numbering 
in the low hundreds. However, the Redwood Creek and Mattole River 
populations appear small, and little is known about other populations 
including various tributaries of the Eel River (i.e., Larabee Creek, 
North Fork Eel, and South Fork Eel)'' (Williams et al. 2016). 
Furthermore, Spence et al. (2008) defined representation and redundancy 
criteria to specifically account for persistence of major life-history 
types in assessing viability, and considered it ``highly likely that, 
at a minimum, the representation and redundancy criteria are not being 
met for summer-run steelhead.''

Distinct Population Segment Determination

    The Petitioner requested we delineate and list a NC summer-run 
steelhead DPS. As described above, the ESA's definition of ``species'' 
includes ``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.'' The DPS Policy requires the 
consideration of two elements when deciding whether a population is a 
DPS: (1) The discreteness of the population segment in relation to the 
remainder of the species to which it belongs; and (2) the significance 
of the population segment to the species to which it belongs.
    A population segment of a vertebrate species may be considered 
discrete if it satisfies either one of the following conditions: (1) It 
is markedly separated from other populations of the same taxon as a 
consequence of physical, physiological, ecological, or behavioral 
factors (and quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation); or (2) it is 
delimited by international governmental boundaries within which 
differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the ESA. If a population 
segment is found to be discrete under one or both of the above 
conditions, its biological and ecological significance to the taxon to 
which it belongs is evaluated. Factors that can be considered in 
evaluating significance may include, but are not limited to: (1) 
Persistence of the discrete population segment in an ecological setting 
unusual or unique for the taxon; (2) evidence that the loss of the 
discrete population segment would result in a significant gap in the 
range of a taxon; (3) evidence that the discrete population segment 
represents the only surviving natural occurrence of a taxon that may be 
more abundant elsewhere as an introduced population outside its 
historic range; or (4) evidence that the discrete population segment 
differs markedly from other populations of the species in its genetic 
characteristics.

Considerations for Criterion 1: Discreteness of the Population Segment

    We considered whether NC summer-run steelhead are markedly 
separated from other populations of NC steelhead as a consequence of 
physical, physiological, ecological, or behavioral factors. 
Quantitative measures of genetic or morphological discontinuity were 
also considered. Northern California summer-run and winter-run 
steelhead are physically distinguishable only for a short, albeit 
important, part of their life-cycle, i.e., during adult freshwater 
migration following return from the ocean and summer holding in 
freshwater. Adult summer-run steelhead enter freshwater between April 
and October, arriving in sexually immature condition and holding in 
deep, cold pools for as long as six-eight months before moving into 
natal streams to spawn. In contrast, adult winter-run steelhead enter 
freshwater and migrate into natal streams between December and April, 
arriving in reproductive condition and spawning shortly thereafter. No 
consistent differences have been documented over the rest of their life 
history, including during the juvenile rearing, smolting, and sub-adult 
marine phases. Furthermore, while the redds and juveniles of the 
summer-run and winter-run steelhead may be somewhat spatially and/or 
temporally partitioned, the extent of this partitioning is highly 
variable among specific spawning tributaries as well as among years. 
The degree of this separation is dependent on changes in geomorphology, 
rainfall patterns, temperatures, and other climate variables, leading 
to incomplete and fluctuating separation at all stages of their life-
cycle, as well as mating between life-history types when conditions 
limit their separation. Importantly, the high variability in the 
natural hydrograph of the Middle Fork Eel River and other coastal 
rivers that support Northern California summer-run steelhead is unlike 
the hydrographs in the snow melt-driven streams of the interior 
Columbia or Sacramento rivers, which may separate early- and late-
migrating adults in a more predictable manner. This suggests that there 
will be a larger amount of variation among years in the degree to which 
a particular natural flow barrier temporally separates migrating adult 
steelhead in coastal watersheds.
    The Petitioner presented new genetic evidence to suggest that the 
summer-run steelhead populations may qualify as a separate DPS from the 
winter-run populations. The Petitioner contends that the findings from 
recently published articles on the evolutionary basis of premature 
migration in Pacific salmon (Prince et al. 2017; Thompson et al. 2018) 
indicate that summer-run steelhead in the NC steelhead DPS

[[Page 6530]]

should be considered a separate DPS. After careful consideration of the 
new evidence presented, and the best available genetic data, the Panel 
concluded that summer-run and winter-run steelhead should remain 
together in a single Northern California steelhead DPS.
    Hess et al. (2016), Prince et al. (2017) and Thompson et al. (2018) 
have studied the relationship between genetic material from a portion 
of the genome that includes the Greb1L gene (otherwise referred to as 
the Greb1L region of the genome) and run-timing in Chinook salmon and 
steelhead. The authors characterized the Greb1L region as two alleles 
(different forms) and three genotypes (different combinations of the 
alleles): Individuals with two early run-timing alleles (early run 
homozygotes), individuals with two late run-timing alleles (late run 
homozygotes), and individuals with one allele for the early and one for 
the late run-timing (heterozygotes).
    To understand whether variation in the Greb1L-region is a useful 
basis to support separation of summer-run and winter-run NC steelhead 
into two DPSs, we must first understand the distribution of individuals 
present in this geographic area representing different genotypic 
categories under consideration. Data collected by the SWFSC clearly 
show that many O. mykiss collections in California contain individuals 
with all three Greb1L-region genotypes present at a given place and 
time (Pearse et al. 2019). Furthermore, Greb1L-region variation is 
distributed broadly among populations, including the widespread 
occurrence of heterozygotes and the presence of both summer and winter 
homozygotes in many populations without documented expression of the 
summer run-timing. This demonstrates that this genetic variation is not 
uniquely partitioned into summer-run and winter-run steelhead DPSs, but 
is broadly distributed across a range of interconnected populations 
with variable phenotypes (observable characteristics). This conclusion 
is further supported within the NC steelhead DPS by analyses provided 
as part of a public comment, showing the distribution of Greb1L-region 
variants throughout the Eel River system (S. Kannry, public comment).
    Notably, Prince et al. (2017) did not observe the overlapping 
distribution of the Greb1L-region genotypes because they intentionally 
selected sample locations to represent the most divergent examples of 
these life-history types, including the summer-run samples from the 
Middle Fork Eel River and winter-run from the upper mainstem Eel River 
(Van Arsdale Fisheries Station). Prince et al. (2017) intentionally 
excluded samples from locations with less clearly defined summer-run or 
winter-run phenotypes because they represented intermediate phenotypes 
(e.g., ``fall-run'' steelhead in the South Fork of the Trinity River). 
As a result, the Prince et al. (2017) data were not informative with 
respect to questions involving the temporal or geographic distribution 
of genetic variation in the Greb1L region, the relative frequency, 
dominance, or relative fitness of Greb1L-region genotypes in different 
locations, or the extent of gene flow between summer-run and winter-run 
steelhead.
    In addition to the above examples, data from the Van Arsdale 
Fisheries Station indicates considerable overlap in the return timing 
of the Greb1L-region genotypes. The data show a nearly complete overlap 
in the return timing of individuals with the heterozygous and winter-
run Greb1L-region genotypes. The data also document that some 
individuals with the homozygous summer-run genotypes were apparently 
migrating during the typical winter-run migration period (Pearse et al. 
2019). Furthermore, this information indicates that matings between 
parents of with alternate Greb1L-region genotypes must occur, resulting 
in full-sibling families with a mix of Greb1L-region genotypes.
    Thus, designation of separate summer-run and winter-run DPSs would 
both ignore the contribution of Greb1L-heterozygous individuals to 
these populations and potentially create situations in which full-
siblings of these matings would be divided into different species under 
the ESA. More simply, ignoring the contribution of Greb1L-heterozygous 
individuals could create a situation in which a single redd would 
produce fish assigned to different DPSs.
    While our understanding of the specific genetic basis of run-timing 
is improved by the data presented in Prince et al. (2017), these new 
genetic data do not substantially change our understanding of the 
biology of summer-run and winter-run steelhead, as run timing has been 
recognized as a proxy for the underlying genetic variation (Dizon et 
al. 1992; Waples 2006). It was understood that there was a genetic 
basis for these traits long before biologists could say exactly what 
that basis was (Clemento 2006; Pearse 2016). In addition, it is likely 
that there are additional genes that contribute to run timing 
expression (Abad[iacute]a-Cardoso et al. 2013), and that different 
parts of the species' genetic material contain adaptive genetic 
variation associated with other, unknown, traits important to local 
adaptation within the NC steelhead DPS. Thus, despite the finding that 
variation in the Greb1L region is strongly associated with run-timing 
in steelhead, our understanding of the evolutionary dynamics of this 
and other genetic variation is not fundamentally altered by this 
knowledge. The available data on genetic variation continue to support 
a model in which summer-run steelhead evolved from existing genetic 
variation, in populations dominated by winter-run steelhead, where and 
when the ecological conditions capable of supporting the summer-run 
life history exist (Arciniega et al. 2016).
    Overall, while summer-run and winter-run steelhead are nominally 
recognizable as distinct life-history types, they occupy dynamic and 
partially overlapping habitats incompletely separated by waterfalls, 
dams, or other barriers to migration. It is also clear that there is 
variable but active and ongoing gene flow between these life-history 
types over ecological and evolutionary timescales. The lack of physical 
barriers separating summer-run and winter-run within the range of the 
NC steelhead DPS and the fact that they are indistinguishable for much 
of their life-cycle further suggest that they cannot be managed 
separately, just as all juvenile O. mykiss below barriers to anadromy 
are de facto considered to be steelhead due to their ``similarity of 
appearance'' (Hey et al. 2005; NMFS 2006). Based on all of the above 
information, we conclude that the summer-run population of steelhead is 
not discrete from the winter-run population in the NC steelhead DPS. 
Thus, splitting these summer-run and winter-run groups would create a 
similar situation to the one that was rejected by the Alsea decision 
(Alsea Valley Alliance v. Evans, No. 99-6265-HO, Sept. 10, 2001), which 
ruled against listing below the species level under the ESA. This 
interpretation is also consistent with that of an earlier NMFS review 
of a petition to list summer steelhead in Deer Creek, Washington, that 
concluded that they should not be considered a separate species under 
the ESA (59 FR 59981; November 21, 1994).

Considerations for Criterion 2: Significance of the Population Segment

    Although the Panel found, and we concurred, that NC summer-run 
steelhead do not qualify as a ``discrete'' population, the Panel 
elected to examine the second DPS criterion.
    The success of the species O. mykiss both in its native range and 
globally is due at least in part to the resilience it

[[Page 6531]]

gets from being able to express a diverse array of life-history 
strategies. These strategies can include adult steelhead run-timing 
variation and others such as variation in juvenile migratory behavior 
(Hayes et al. 2011; Moore et al. 2014), variation in adult age-at-
return, within-season variance in spawn timing (Abad[iacute]a-Cardoso 
et al. 2013), variation in the half-pounder life history (steelhead 
that return from the ocean after only two to four months of saltwater 
residence, are generally sexually immature, and migrate back to 
saltwater the following spring: Roelofs 1983; Hayes et al. 2016), and 
variation in non-anadromous life histories (freshwater adfluvial and 
resident life histories; Hayes et al. 2011). This diversity allows 
different individuals in the species to maximize their fitness by 
taking advantage of the habitat conditions present in a particular 
place and time. Given the importance of inter-annual variation in this 
geographic area and its effect on the ability of streams in the NC 
steelhead DPS geographic range to support salmonids (Power et al. 
2015), this diversity clearly adds resilience to the NC steelhead DPS 
and supports its continued survival. Life-history variants that do best 
in one year may not have the highest fitness in a different year, but 
collectively they can maintain a viable population size and high 
genetic diversity (i.e., the portfolio effect: Schindler et al. 2015; 
Moore et al. 2014; Brennan et al. 2019). The contribution of the many 
diverse life-history forms is critical to the resilience of O. mykiss.
    With respect to the significance of the summer-run steelhead to the 
Northern California steelhead DPS, this life-history diversity is 
already recognized by its explicit inclusion in the recovery and 
viability documents developed for salmon and steelhead in this area 
(Spence et al. 2008; NMFS 2016b; Williams et al. 2016). The recovery 
plans were based on viability criteria, which in turn were based on the 
viable salmonid population (VSP) concept (McElhany et al. 2000). The 
VSP concept recognizes that life-history diversity is: (1) A key 
parameter; and (2) hierarchical in nature (from populations on up to 
species). These summer-run populations have been explicitly identified 
as having viability criteria based on their shorter-term demographic 
independence and the need to maintain the appropriate building blocks 
for recovery (i.e., population units capable of persisting in relative 
isolation of other units). Having summer-run populations as substrata 
within diversity strata (and essential for viability) provides the 
umbrella under which longer-term evolutionary processes are maintained. 
However, it is also important to keep in mind that all of the other 
life history variations described above in the species O. mykiss are 
likely to be of equal if not greater significance to the resilience of 
the species as the variation in adult migration timing associated with 
the Greb1L region. Thus, there is no clear basis for deciding that 
adult migratory timing variation should be prioritized more highly than 
the other, similarly important and diverse characteristics of this 
highly variable species, or that separating any of these life history 
variations into separate management units would provide a benefit given 
their interdependent and dynamic relationships.

NC Steelhead DPS Conclusions

    We conclude that summer-run and winter-run steelhead should remain 
together in a single Northern California steelhead DPS. The best 
available data indicate that summer-run steelhead cannot be listed as a 
separate DPS from winter-run steelhead, as the two groups maintain an 
ongoing and interconnected genetic legacy. Retention of both life-
history types in a single DPS, however, does not indicate a lack of 
recognition that summer-run steelhead are an important component of the 
DPS, or suggest that measures should not be taken to protect and 
improve habitat, including access to upstream habitats through dam 
removals, fish passage programs, reduced water diversions, etc. Rather, 
it is an acknowledgment that the run-types are fundamental parts of the 
listed unit as a whole and should not be separated from each other. As 
noted above, this is explicitly addressed in the NMFS status reviews 
and recovery plans through recognition of the need to focus protection 
on and consider populations of both of these run-types in assessing 
recovery status (NMFS 2016a, NMFS 2016b; Spence et al. 2008).

Final Determination

    Section 4(b)(1) of the ESA requires that NMFS 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 the information 
contained in the petition, public comments submitted on the 90-day 
finding (84 FR 16632; April 22, 2019), and the DPS configuration review 
report, and other published and unpublished information, and we have 
consulted with species experts and individuals familiar with the NC 
steelhead DPS.
    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 NC summer-run 
steelhead do not constitute a DPS. Accordingly, NC summer-run steelhead 
does not meet the definition of a species, and thus, NC summer-run 
steelhead does not warrant listing as a separate DPS.
    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: January 30, 2020.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.
[FR Doc. 2020-02174 Filed 2-4-20; 8:45 am]
BILLING CODE 3510-22-P