Endangered and Threatened Wildlife and Plants; Endangered Species Status for the San Francisco Bay-Delta Distinct Population Segment of the Longfin Smelt, 61029-61049 [2024-16380]
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Federal Register / Vol. 89, No. 146 / Tuesday, July 30, 2024 / Rules and Regulations
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[FR Doc. 2024–16570 Filed 7–29–24; 8:45 am]
BILLING CODE 6560–50–P
DEPARTMENT OF HEALTH AND
HUMAN SERVICES
42 CFR Part 71
[Docket No. CDC–CDC–2023–0051]
RIN 0920–AA82
Control of Communicable Diseases;
Foreign Quarantine: Importation of
Dogs and Cats; Correction
Centers for Disease Control and
Prevention (CDC), Department of Health
and Human Services (HHS).
ACTION: Final rule; correction.
AGENCY:
The Centers for Disease
Control and Prevention (CDC) in the
Department of Health and Human
Services (HHS) announces a technical
correction to the final rule published on
May 13, 2024, regarding the importation
of dogs and cats into the United States.
The final rule contained a technical
error. HHS/CDC is therefore publishing
this amendment to the final rule
correcting an error in amending
instructions to the Office of the Federal
Register.
DATES: Effective on August 1, 2024.
FOR FURTHER INFORMATION CONTACT:
Ashley C. Altenburger, J.D., Division of
Global Migration Health, Centers for
Disease Control and Prevention, 1600
Clifton Road NE, MS–H16–4, Atlanta,
Georgia 30329. Telephone: 1–800–232–
4636.
SUPPLEMENTARY INFORMATION: On May
13, 2024, HHS/CDC published a final
rule (89 FR 41726) that included a
technical error. Therefore, HHS/CDC is
publishing this notice to correct the
technical error that was made in the
final rule.
Section 553(b)(B) of the
Administrative Procedure Act (APA), 5
U.S.C. 553(b)(B), provides that, when an
agency for good cause finds that notice
and public procedure are impracticable,
unnecessary, or contrary to the public
interest, the agency may issue a rule
without providing notice and an
opportunity for public comment. We
have determined that it is unnecessary
to provide prior notice and the
opportunity for public comment
because the technical correction being
made, as discussed below, address only
a minor publication error that does not
substantially change agency actions
taken in the final rule. For the same
reasons we find good cause to make the
correction effective on publication.
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SUMMARY:
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Summary of the Technical Correction
to 42 CFR Part 71—Foreign Quarantine;
Importation of Dogs and Cats
The final rule contains instructions to
the Office of the Federal Register
explaining how § 71.51, Dogs and cats,
should appear once published in the
Code of Federal Regulations. In
amending instruction 3.j. to § 71.51,
appearing at 89 FR 41837, HHS/CDC
included instructions ‘‘adding
paragraphs (h) through (ff).’’ However,
the final rule contained updated
provisions through paragraph (gg) and
should have indicated that HHS/CDC is
‘‘adding paragraphs (h) through (gg).’’
We are therefore making this technical
correction to ensure that paragraph (gg)
is published in the Code of Federal
Regulations as HHS/CDC intended and
as discussed in the final rule.
Correction
For the reasons noted above, in FR
Doc. 2024–09676, beginning on page
41726 in the Federal Register of
Monday, May 13, 2024, the following
correction is made:
§ 71.51
[Corrected]
1. On page 41837, in the third column,
in amendment 3.j. for § 71.51, the
instruction ‘‘Adding paragraphs (h)
through (ff)’’ is corrected to read
‘‘Adding paragraphs (h) through (gg)’’.
■
The effective date for the final
rule published June 27, 2024, at 89 FR
53502, is delayed from August 26, 2024,
to September 16, 2024.
FOR FURTHER INFORMATION CONTACT: Ms.
Jennifer D. Johnson, telephone 703–
717–8226.
SUPPLEMENTARY INFORMATION: On June
27, 2024, DoD published a final rule
amending the Defense Federal
Acquisition Regulation Supplement
(DFARS) to implement section 2881 of
the National Defense Authorization Act
for Fiscal Year 2024 (Pub. L. 118–31).
Section 2881 increased the statutory
limitation on the amount that may be
earned by contractors providing certain
architect and engineering services under
contracts with the Departments of the
Army, Navy, and Air Force. The
effective date of the final rule has been
postponed from August 26, 2024, to
September 16, 2024, to comply with the
Congressional Review Act; the final rule
is a major rule as defined by 5 U.S.C.
804.
DATES:
Jennifer D. Johnson,
Editor/Publisher, Defense Acquisition
Regulations System.
[FR Doc. 2024–16715 Filed 7–29–24; 8:45 am]
BILLING CODE 6001–FR–P
DEPARTMENT OF THE INTERIOR
Elizabeth Gramling,
Executive Secretary, Department of Health
and Human Services.
Fish and Wildlife Service
[FR Doc. 2024–16681 Filed 7–29–24; 8:45 am]
50 CFR Part 17
BILLING CODE 4163–18–P
61029
[Docket No. FWS–R8–ES–2022–0082;
FXES1111090FEDR–245–FF09E21000]
DEPARTMENT OF DEFENSE
RIN 1018–BG07
Defense Acquisition Regulations
System
[Docket DARS–2024–0019]
Endangered and Threatened Wildlife
and Plants; Endangered Species
Status for the San Francisco Bay-Delta
Distinct Population Segment of the
Longfin Smelt
RIN 0750–AM16
AGENCY:
Defense Federal Acquisition
Regulation Supplement: Architect and
Engineering Service Fees (DFARS
Case 2024–D019); Delay of Effective
Date
SUMMARY:
48 CFR Part 236
Defense Acquisition
Regulations System, Department of
Defense (DoD).
ACTION: Final rule; delay of effective
date.
AGENCY:
DoD is postponing the
effective date of the final rule published
in the Federal Register on June 27,
2024. As published, the rule was to be
effective August 26, 2024.
SUMMARY:
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Fish and Wildlife Service,
Interior.
ACTION: Final rule.
We, the U.S. Fish and
Wildlife Service (Service), determine
endangered species status under the
Endangered Species Act of 1973, as
amended (Act), for the San Francisco
Bay-Delta distinct population segment
(DPS) of longfin smelt (Spirinchus
thaleichthys), a fish species of the
Pacific Coast. This rule extends the
protections of the Act to this DPS and
adds it to the List of Endangered and
Threatened Wildlife.
DATES: This rule is effective August 29,
2024.
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Federal Register / Vol. 89, No. 146 / Tuesday, July 30, 2024 / Rules and Regulations
This final rule is available
on the internet at https://
www.regulations.gov. Comments and
materials we received on the proposed
rule are available for public inspection
at https://www.regulations.gov at Docket
No. FWS–R8–ES–2022–0082.
Availability of supporting materials:
Supporting materials we used in
preparing this rule, such as the species
status assessment report, are available at
https://www.regulations.gov at Docket
No. FWS–R8–ES–2022–0082.
FOR FURTHER INFORMATION CONTACT:
Donald Ratcliff, Field Supervisor, U.S.
Fish and Wildlife Service, San
Francisco Bay-Delta Fish and Wildlife
Office, 650 Capitol Mall, Suite 8–300,
Sacramento, CA 95814; telephone 916–
930–5603. Individuals in the United
States who are deaf, deafblind, hard of
hearing, or have a speech disability may
dial 711 (TTY, TDD, or TeleBraille) to
access telecommunications relay
services. Individuals outside the United
States should use the relay services
offered within their country to make
international calls to the point-ofcontact in the United States.
SUPPLEMENTARY INFORMATION:
ADDRESSES:
khammond on DSKJM1Z7X2PROD with RULES
Executive Summary
Why we need to publish a rule. Under
the Act, a species (including a distinct
population segment of a species)
warrants listing if it meets the definition
of an endangered species (in danger of
extinction throughout all or a significant
portion of its range) or a threatened
species (likely to become endangered
within the foreseeable future throughout
all or a significant portion of its range).
If we determine that a species warrants
listing, we must list the entity promptly
and designate the species’ critical
habitat to the maximum extent prudent
and determinable. We have determined
that the San Francisco Bay-Delta
distinct population segment (DPS) of
longfin smelt (hereafter Bay-Delta
longfin smelt) meets the definition of an
endangered species; therefore, we are
listing it as such. Listing a species as an
endangered species can be completed
only by issuing a rule through the
Administrative Procedure Act
rulemaking process (5 U.S.C. 551 et
seq.).
What this document does. This rule
lists the Bay-Delta longfin smelt as an
endangered species under the
Endangered Species Act and adds the
Bay-Delta longfin smelt to the List of
Endangered and Threatened Wildlife in
title 50 of the Code of Federal
Regulations at 50 CFR 17.11(h).
The basis for our action. Under the
Act, we may determine that a species is
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an endangered or threatened species
because of any of five factors: (A) The
present or threatened destruction,
modification, or curtailment of its
habitat or range; (B) overutilization for
commercial, recreational, scientific, or
educational purposes; (C) disease or
predation; (D) the inadequacy of
existing regulatory mechanisms; or (E)
other natural or manmade factors
affecting its continued existence. We
have determined that the Bay-Delta
longfin smelt is endangered due to the
following threats: altered hydrology
(Factor A; largely attributable to water
management, including water
diversions and channel modifications),
nonnative species (Factors C and E), and
the effects of climate change (Factor E;
by exacerbating drought, decreasing
river and stream flows, and increasing
air and water temperatures).
Section 4(a)(3) of the Act requires the
Secretary of the Interior (Secretary), to
the maximum extent prudent and
determinable, to designate critical
habitat concurrent with listing. We will
publish a proposed critical habitat rule
in a future edition of the Federal
Register.
Previous Federal Actions
On October 7, 2022, the proposed rule
to list the Bay-Delta longfin smelt
published in the Federal Register (87
FR 60957). On February 27, 2023, we
published a document in the Federal
Register (88 FR 12304) that announced
a public hearing and reopened the
comment period for the proposed rule.
Please see the proposed listing rule for
a detailed description of previous
Federal actions concerning this species.
On December 22, 2023, San Francisco
Baykeeper (Baykeeper), a nonprofit
corporation, filed a complaint in the
U.S. District Court for the Northern
District of California (San Francisco
Baykeeper v. United States Fish and
Wildlife Service, et al. (Case 4:23–cv–
06601–LB)) challenging the Service’s
failure to complete its statutory
obligations to make a final listing
determination for the Bay-Delta longfin
smelt. On April 5, 2024, the court issued
an order requiring us to submit the final
listing determination to the Office of the
Federal Register by July 22, 2024. This
document satisfies our requirement for
completion of our final listing rule.
Peer Review
A species status assessment (SSA)
team prepared an SSA report for the
Bay-Delta longfin smelt. The SSA team
was composed of Service biologists, in
consultation with other species experts
including those from the California
Department of Fish and Wildlife. The
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SSA report represents a compilation of
the best scientific and commercial data
available concerning the status of the
Bay-Delta longfin smelt, including the
impacts of past, present, and future
factors (both negative and beneficial)
affecting the species.
In accordance with our joint policy on
peer review published in the Federal
Register on July 1, 1994 (59 FR 34270),
and our August 22, 2016, memorandum
updating and clarifying the role of peer
review of listing actions under the Act,
we solicited independent scientific
review of the information contained in
the draft Bay-Delta longfin smelt SSA
report (Service 2021, entire). As
discussed in the proposed rule, we sent
the 2021 SSA report to five independent
peer reviewers and received three
responses. The peer reviews can be
found at https://www.regulations.gov at
Docket No. FWS–R8–ES–2022–0082
under supporting documents. In
preparing the proposed rule, we
incorporated the results of these
reviews, as appropriate, into a revised
draft SSA report (Service 2022, entire)
and made this 2022 version available to
the public on https://
www.regulations.gov at Docket No.
FWS–R8–ES–2022–0082 during the
open comment periods. We have since
incorporated any additional edits as
appropriate based on public comments
received during the public comment
periods into the current SSA report,
which is the foundation for this final
rule (Service 2024, entire). A summary
of the peer review comments and our
responses can be found in the Summary
of Comments and Recommendations,
below.
Summary of Changes From the
Proposed Rule
Since the October 7, 2022, proposed
rule and February 27, 2023, document
reopening the comment period and
announcing a public hearing were
published, we received comments from
the public on the proposed listing rule
and 2022 SSA report. After the second
comment period closed on March 29,
2023, we also received additional
comments on August 16, October 23,
and December 12, 2023, from
representatives of the Coalition for a
Sustainable Delta. The Coalition also
provided comments during the open
comment periods for the proposed rule
to https://www.regulations.gov at Docket
No. FWS–R8–ES–2022–0082 (see
documents FWS–R8–ES–2022–0082–
0009 and –0024).
After reviewing all the information we
received, we updated and revised the
2022 SSA report to incorporate any
grammatical edits, clarifications, and
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formatting changes. We also revised the
count-based population viability
analysis (see Service 2024, appendix B)
based on information received from
comments on the proposed rule and
peer review of the information
associated with publication of the
analysis (Tobias et al. 2023, entire) in a
scientific journal. The revisions to the
analysis were associated with our
methodology of estimating population
growth rates and assisted in accounting
for observation error in our estimates.
Additionally, we also compared
density-dependent model formulations
to confirm sufficiency of our densityindependent model. The changes made
to the SSA report and appendix B did
not significantly change our
determination of status of the Bay-Delta
longfin smelt in this final rule.
Additionally, in the October 7, 2022,
proposed listing rule, we determined
the designation of critical habitat for the
DPS to be not determinable due to a lack
of necessary information to complete
our analysis. We are currently in the
review process of determining critical
habitat for the DPS, and a proposed rule
will be forthcoming (see Critical Habitat,
below).
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Summary of Comments and
Recommendations
In the proposed rule published on
October 7, 2022 (87 FR 60957), and
reopening document published on
February 27, 2023 (88 FR 12304), we
requested that all interested parties
submit written comments on the
proposal by December 6, 2022, and
March 29, 2023, respectively. We also
contacted appropriate Federal and State
agencies, scientific experts and
organizations, and other interested
parties and invited them to comment on
the proposal. A newspaper notice
inviting general public comment was
published in the Sacramento Bee on
October 10, 2022 (McClatchy 2022,
entire). On November 21, 2022, we
received a written request from the
public for a public hearing (Barajas et al.
2022, entire). We held a virtual public
hearing on the proposed listing rule on
March 14, 2023, as described in our
February 27, 2023, Federal Register
document (88 FR 12304 at 12305)
reopening the comment period and
announcing the virtual public hearing.
All substantive information received
during both comment periods or
subsequently has either been
incorporated directly into this final
determination as appropriate or is
addressed below.
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Peer Reviewer Comments
As discussed in Peer Review above,
we received comments from three peer
reviewers on the draft SSA report
(Service 2021, entire). We reviewed all
comments we received from the peer
reviewers for substantive issues and
new information regarding the
information contained in the 2021 SSA
report. The peer review comments
primarily fell into two main categories:
(1) comments that provided grammatical
or editorial corrections or minor
clarifications of fact or that had no
suggestions for changes to the SSA
report but were either just expressing
agreement or opposition and (2)
comments that would affect the
interpretation of available data and
information presented in the SSA
report. Peer review greatly assisted us to
clarify our presentation of the
substantial body of scientific
information on Bay-Delta longfin smelt
in the revised draft SSA report (Service
2022, entire) and the current SSA report
(Service 2024, entire). Peer reviewer
comments are addressed in the
following summary. As discussed
above, because we conducted this peer
review prior to the publication of our
proposed rule, we had already
incorporated all applicable peer review
comments into 2022 version of the SSA
report, which was the foundation for the
proposed rule. Additional comments
received from the public have also been
incorporated into the current version of
the SSA report as necessary (Service
2024, entire) and together they are the
foundation of this final rule.
(1) Comment: One peer reviewer
stated that use of survey indices is not
a good metric for data analysis and
suggested using catch data instead.
Our response: We acknowledge that
survey indices are not absolute census
measures. However, we did compare
existing Bay-Delta longfin smelt catch
data (catch-per-unit-effort (CPUE) values
from Stompe et al. 2020, entire) to the
survey indices used in our analysis and
got very similar results to what is
presented in appendix B of the 2022 and
2024 SSA reports (Service 2022, pp.
110–123, Service 2024, pp. 115–128). As
noted in the introduction of the
technical note, CPUE and the
Interagency Ecological Program (IEP)
estimates both constitute indices of BayDelta longfin smelt abundance. Our use
of abundance indices was not to
determine the exact number of BayDelta smelt individuals but to use the
multiple survey indices to determine
trend information for the Bay-Delta
longfin smelt. We consider the multiple
survey efforts, which use varying
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61031
sampling methods, as an appropriate
measure to determine such trend
information.
(2) Comment: One peer reviewer
mentioned that our analysis included a
‘‘temporal bias’’ in the 20-mm and fall
midwater trawl (FMWT) survey data
(referring to the ‘‘wet’’ period starting
the data series compared to the recent
dry period). The reviewer suggested that
we consider comparing wet periods to
wet periods and dry periods to dry
periods to more appropriately
demonstrate the decline.
Our response: The section of the draft
SSA report referred to by the reviewer
(Service 2021, pp. 124–158) was
intended to be a descriptive discussion
on the statistical analysis of the
abundance indices by the various
survey efforts through time. In the
revised draft SSA report (Service 2022,
pp. 107–192), we revised the section to
focus more on the descriptive statistics
without calculating percent declines to
avoid any possible perception of false
precision within a decades-long data
series. In the population viability
analysis presented in our revised draft
SSA report (Service 2022, appendix B)
and now the updated modeling effort
(the analysis has since published as
Tobias et al., 2023, entire) described in
appendix B of the current SSA report
(Service 2024, appendix B), we interpret
the full-time course of the suite of
available data that includes any
variance between wet or dry years.
(3) Comment: One peer reviewer
suggested that the geographic and depth
bias to FMWT make it ineffective as a
survey for longfin smelt due to the fact
that the FMWT does not sample the
entire estuary or the entire water
column.
Our response: The comment correctly
points out that there are differences in
spatial coverage both geographically and
within the water column amongst the
various survey efforts. However, we did
not rely entirely on the FMWT as the
only information in our analysis. To
avoid any bias from any one survey
effort, we used the information from all
survey efforts in our modeling and
overall analysis. Because none of the
currently existing long-term monitoring
surveys’ sampling designs provides
estuary-wide and full water column
coverage, we consider that our
methodology as identified in appendix
B of the current SSA report (Service
2024) to determine trend information
and extinction risk is a robust technical
analysis as it helps reduce the effects of
inflated variance through inverse
weighting and is based on the best
available scientific information
available.
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(4) Comment: One peer reviewer
disagreed with our description of the
importance of freshwater flow into the
San Francisco Bay estuary and cited an
analysis that indicated that freshwater
flow was not the primary factor
contributing to the decline of Bay-Delta
longfin smelt (Phillis 2019, entire). The
peer reviewer points to information
indicating that freshwater flow into the
estuary did not cause as substantial
population rebound during recent wet
periods as has been observed in prior
decades and that the relationship
between freshwater flow and population
abundance is weakening (Tamburello et
al. 2019, entire). The peer reviewer
further points out that juvenile-to-adult
survival was not significantly affected
by freshwater flow into the estuary
(Nobriga and Rosenfield 2016, entire).
Our response: We acknowledge that
the relationship between increased
freshwater flow and population
abundance has recently been found to
be decreasing. As a result, we have
amended the SSA report to state that
freshwater flow, while a primary driver
of abundances, is not necessarily the
primary driver influencing abundance
of the current population (Service 2024,
pp. 28–43). However, the peer
reviewer’s statement overlooks the
influence of a massively declining adult
population on the abundance of
offspring that can be produced when
favorable freshwater flow conditions
exist. Other factors such as the size of
the current adult breeding population
and food resource limitations also play
a role in the current status of the DPS,
and we made clarifications in the
current SSA report to also point to these
other factors (Service 2024, pp. 35–36).
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Public Comments
Influences on Water Temperature and
Salinity
(5) Comment: We received several
comments contending that the 2022
SSA report and proposed rule
mischaracterize the relationship
between water temperatures and San
Francisco Bay Delta outflow. The
commenters stated that estuary water
temperatures are governed by a
multitude of complex factors related to
prevailing atmospheric conditions and
are not influenced by San Francisco Bay
Delta outflow.
Our response: In the 2022 SSA report
and proposed rule, we acknowledge the
complexity of factors influencing water
temperature in the San Francisco Bay
Delta. We agree with commenters that
estuary water temperatures are governed
by a multitude of complex factors and
that atmospheric forcing is the
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dominant factor in determining water
temperature in the estuary. However,
existing literature suggests increased
inflow can influence San Francisco Bay
Delta temperatures. Some studies have
found evidence that increased San
Francisco Bay Delta inflow can lead to
cooler than predicted temperatures in
the San Francisco Bay Delta over short
timespans (Wagner et al. 2011, p. 551;
Wagner 2012, p. 78). The current SSA
report better clarifies the relationship
between San Francisco Bay Delta
inflow/outflow and water temperatures
(Service 2024, pp. 27–28).
(6) Comment: One commenter
suggested that our conclusions
regarding water temperature conditions
are not accurate. Specifically, the
commenter stated that temperature
conditions in the San Francisco BayDelta never exceed 20 degrees Celsius
(°C) (68 degrees Fahrenheit (°F)) in the
winter-spring in the low-salinity zone,
suggesting that high water temperatures
are not a threat to larval and post-larval
Bay-Delta longfin smelt.
Our response: The commenter’s
statement that water temperatures never
exceed 20 °C (68 °F) in the winter and
spring within the low-salinity zone is
incorrect. Water temperatures in May
within the low-salinity zone have been
found to exceed this temperature
(California Department of Water
Resources 2020, entire). Lab studies
sampling Bay-Delta longfin smelt
collected within the San Francisco Bay
have shown that water temperatures
above 20 °C (68 °F) cause molecular
stress responses (Jeffries et al. 2016,
entire) and that temperatures greater
than 15 °C (59 °F) may impair the
viability of larval Bay-Delta longfin
smelt (Yanagitsuru et al. 2021, entire).
Water temperatures are predicted to
increase in the estuary as a result of
climate change and are likely to be an
important factor in the future condition
of the DPS (Service 2024, pp. 63–71).
Food Limitation
(7) Comment: A commenter stated
that the 2022 SSA report fails to support
the conclusion that food limitation may
act as a stressor on the Bay-Delta longfin
smelt.
Our response: In our discussion of
prey availability and the decline of the
DPS in the 2022 SSA, we presented the
current scientific understanding and our
conclusions are based on the best
scientific information available (Service
2022, pp. 35–36). We acknowledge in
the current SSA report that the prey
species Eurytemora affinis has not been
statistically linked to the survival of
larval longfin smelt (Service 2024, pp.
35–36). We also acknowledge in the
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2024 SSA report that although DPS
abundance was observed to decline
following the overbite clam (P.
amurensis) invasion, no direct statistical
support for a bottom-up longfin-mysid
link has been established (Service 2024,
pp. 35–36). The two primary prey taxa
of the DPS have substantially declined
compared to historical levels when
overbite clam was not present
(Kimmerer and Orsi 1996, p. 412).
Research into the invasion of the
nonnative overbite clam into the
estuary, although not definitive, does
suggest there is a possible link between
the invasion and the subsequent decline
of longfin smelt (Kimmerer 2002, p. 47;
Feyrer et al. 2003, pp. 284–286;
Thomson et al. 2010, p. 1443) with more
recent research finding a significant
positive correlation between available
prey biomass and feeding success of
Bay-Delta longfin smelt in the estuary,
suggesting prey availability could
influence growth and survival (Barros et
al. 2022, p. 1773). The inability to
statistically link declines in prey
directly with declines in the DPS does
not eliminate the likelihood that prey
abundances are somehow linked to
survival, but it suggests that factors
affecting survival are complex and they
may be partly attributable to prey
abundances.
Entrainment
(8) Comment: We received two
comments regarding entrainment rates
of the DPS as a result of water diversion
from the estuary. One commenter
suggested the entrainment rates cited in
the 2022 SSA report were overestimates
because estimates were based on data
that did not cover the full geographic
extent of DPS larvae within the San
Francisco Bay-Delta. The other
commenter stated that the 2022 SSA
report underestimates entrainment in
the studies cited in the 2022 SSA report
because the models excluded juvenile/
adult entrainment, underestimated the
length of time larvae are vulnerable to
entrainment, and failed to account for
indirect mortality.
Our response: The research discussed
in the 2022 SSA report regarding
entrainment has since been published
and is publicly available (Gross et al.
2022, entire; Kimmerer and Gross 2022,
entire). The authors of these papers
acknowledged longfin smelt extend
beyond the geographic extent of the
sampling scheme used in these studies
and took measures to correct for this
bias. The results of these studies suggest
that under current Old and Middle
Rivers (OMR) flow management
strategies, entrainment of Bay-Delta
longfin smelt has not been substantial
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enough to affect DPS population
dynamics. Estimates from these two
studies currently represent the best
commercial and scientific data available
and are discussed in the current SSA
report (Service 2024, pp. 41–43). A pilot
study examining entrainment of larval
smelts is ongoing and aims to answer
some of the current uncertainties. Over
the next few years, life cycle modeling
work by the Service will better quantify
the cumulative impact of entrainment of
multiple life stages on the DPS.
Contribution of Bay Tributaries
(9) Comment: We received multiple
comments expressing concerns
regarding how the 2022 SSA report and
proposed rule addressed portions of the
population that inhabit areas outside of
the sampling footprint of most long-term
surveys, particularly areas in and
around Bay tributaries. Some of these
commenters claim the Service
disregarded this portion of the
population in our determination and
ignored the contribution of San
Francisco Bay-Delta tributaries and
recent restoration efforts of these areas
to the DPS’s current abundance,
pointing to recent research (i.e., Lewis et
al. 2019a and 2019b) as evidence of
population redundancy. The
commenters concluded that because the
Service did not consider the DPS’s use
of these areas in evaluating abundance
of the Bay-Delta longfin smelt, the DPS
is not experiencing population declines
as evidenced by continued inhabitation
of all geographic units in its range, and,
therefore, the DPS is not at substantial
risk of extinction or extirpation in any
portion of its documented range.
Our response: Both the 2022 and 2024
SSA reports frequently acknowledge the
inhabitation of Bay tributaries and
recognize the important role they may
have in reproduction, particularly in
wet years (Service 2022, pp. 12, 19, 24;
Service 2024, pp. 12, 21, 25). However,
substantial contributions of recruits
from these tributaries appear to be
limited to wet years, and typically the
majority of suitable spawning and
rearing habitat is still the estuary’s
major low-salinity zone, which is
usually located between Suisun Bay and
the Delta (Kimmerer et al. 2013, figure
2, p. 7; Lewis et al. 2019a, p. 3; Lewis
et al. 2019b, p. 6). Targeted sampling of
some of these habitats in Bay tributaries
has begun only recently; therefore, no
time series exist on the time scale
required to analyze population trends in
these habitats. As such, there was no
practical method to include data from
these limited studies to inform our
statistical analyses. However, recruits
that hatched in Bay tributaries are
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available to the San Francisco Bay
Study (SFBS) once they enter the larger
Bays, so population contributions from
Bay tributaries should be captured by
SFBS indices.
We agree with commenters that
restoration of the Bay tributaries would
provide valuable benefits to the DPS.
However, these benefits would likely
occur during the spawning and rearing
season of wet years rather than during
the extended summer/fall occupancy of
these habitats as the commenters
suggested. During the summer and fall
when Bay-Delta longfin smelt are
occupying these areas, they appear to be
mostly inhabiting deeper habitat as
evidenced by the higher catch in the
otter trawl surveys compared to the
mid-water trawl surveys (Rosenfield and
Baxter 2007, p. 1586). As such,
restoration of shallower tidal wetlands
in the lower Bay tributaries may not
provide suitable habitat during the
summer and early fall, as temperatures
in these shallow habitats can approach
and exceed the thermal tolerance of
Bay-Delta longfin smelt during these
times.
We disagree with the statement that
the Bay-Delta longfin smelt is not
experiencing population declines as
evidenced by continued inhabitation of
all geographic units in its range. The
complex hydrodynamics of the estuary
results in planktonic larvae and postlarvae with limited mobility to be
widely distributed throughout the
estuary, regardless of whether the
habitat is suitable for any length of time.
Likewise, spawning adults appear to be
primarily oriented to cool water
temperatures, which results in
inhabitation of the ephemerally cool
temperatures of Bay tributaries (Lewis et
al. 2019b, p. 19). Inhabitation and
spawning in these waters beyond the
wettest years likely acts as a population
sink as opposed to a source, as was
observed by lack of recruitment from
these habitats in most years. Lack of
successful recruitment in most years
from these tributaries suggests these
habitats do not provide meaningful
population redundancy.
Outflow-Abundance Relationship
(10) Comment: Some commenters
took issue with our discussion on the
relationship between freshwater flow
and Bay-Delta longfin smelt abundance
and questioned the validity and
predictive power of the outflowabundance relationship pointing to
recent years when observed abundance
indices were below indices predicted by
the relationship.
Our response: The relationship of
freshwater flow and longfin smelt
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production has consistently been
reaffirmed for decades based on the
published literature (Stevens and Miller
1983, pp. 431–432; Jassby et al. 1995, p.
285; Kimmerer 2002, p. 47; Rosenfield
and Baxter 2007, p. 1585; Sommer et al.
2007, p. 274; Kimmerer et al. 2009, p.
381; MacNally et al. 2010, p. 1422;
Thomson et al. 2010, pp. 1439–1440;
Maunder et al. 2015, p. 108; Nobriga
and Rosenfield 2016, p. 53; Kimmerer
and Gross 2022, fig. 2, p. 2735).
Nonetheless, we acknowledge that
freshwater outflow is not a perfect
predictor of Bay-Delta longfin smelt
abundance due to the complexity and
variable nature of habitat within the
estuary and Bay-Delta longfin smelt
population dynamics. The 2022 and
2024 SSA reports acknowledge what
may be step-declines (where
populations decline to a lower
abundance level and do not rebound to
previous levels) or changes in the
intercept of the relationship (Service
2022, pp. 35–37; Service 2024, pp. 35–
37) and acknowledge the decreasing
explanatory power of the flowabundance model (Service 2022, p. 37;
Service 2024, p. 37). The decline of
adult stock and its resulting egg supply
is the most parsimonious reason why
observed indices have been below what
were predicted from data in the
increasingly distant past. The SSA
reports illustrate the point that when
declining spawning stock is considered
in the outflow-abundance model, the
explanatory power of the flowabundance model did not degrade over
time (Service 2022, fig. 3.3, p. 38;
Service 2024, p. 38). Understanding the
biological mechanisms behind the flowabundance relationship is an ongoing
topic of research for the Service and the
broader scientific community in the
estuary.
Low-Salinity Zone Mechanism
(11) Comment: We received a
comment suggesting the expansion of
the low-salinity zone due to increased
freshwater flow should not be
considered a mechanism by which
freshwater flow might influence BayDelta longfin smelt productivity. The
commenter cited Kimmerer et al. (2013)
as evidence that the volume of lowsalinity habitat in the estuary is
unrelated to the DPS’s abundance.
Our response: We agree that current
literature suggests higher outflow
expanding the volume of the lowsalinity zone is inadequate in explaining
the population growth observed during
wet years. In the 2022 SSA report, we
acknowledged that expansion of the
low-salinity zone may be beneficial to
larvae but did not suggest this
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mechanism was a primary driver of the
outflow-abundance relationship
(Service 2022, p. 21). Dr. Kimmerer
provided an additional comment on the
proposed rule suggesting a predominant
mechanism behind the outflowabundance relationship may be a result
of favorable larval transport and
retention in the low-salinity zone and
elevated prey concentrations occurring
during periods of greater freshwater
flow, resulting in higher survival and
abundance. In the 2022 SSA report, we
identified and discussed this
mechanism as well as other postulated
mechanisms that may contribute to the
outflow-abundance relationship
(Service 2022, p. 32). In the proposed
rule summarizing the information from
the 2022 SSA report, we may have
underrepresented the transport and
retention mechanism. We have further
described this mechanism in the 2024
SSA report (Service 2024, pp. 21–22)
and this final rule (see Summary of
Biological Status and Threats below).
(12) Comment: We received a
comment regarding the habitat use of
larval/post-larval Bay-Delta longfin
smelt. The commenter cited Yanagitsuru
et al. (2022), Rahman et al. (2023), and
a presentation to the Estuarine
Ecological Team by Levi Lewis (2023) as
new evidence that the Bay-Delta longfin
smelt larvae are distributed further
downstream and at higher salinities
than previously thought.
Our response: The 2024 SSA report
acknowledges the range of salinities that
larval smelt are known to utilize in the
estuary (Service 2024, p. 34). The lab
studies that the commenter cites are
informative of the physiological salinity
tolerances of larvae but are not
necessarily indicative of habitat use
within the estuary, as such studies
ignore predation, hydrodynamics, and
other relevant physical and ecological
processes. In the wild, larval abundance
has been shown to rapidly decline
above 10 practical salinity unit (PSU)
(Lewis et al. 2019b, p. 30), and peak
recruitment and abundance occur in the
range of 2 to 4 PSU (Hobbs et al. 2010,
p. 564; Grimaldo et al. 2017, p. 8;
Grimaldo et al. 2020, pp. 12–14).
DPS Status
(13) Comment: We received
comments stating that the San Francisco
Bay-Delta longfin smelt does not meet
the criteria of a DPS according to the
Service’s policy because it is not
‘‘markedly separated’’ from the rest of
the longfin smelt population and that
the Bay-Delta population is regularly
mixing with other populations. The
commenter points to research
conducted since our 2012 DPS
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determination regarding dispersal and
connectivity between the Bay-Delta
population and nearby populations
farther north along the California coast.
Our response: Our DPS policy does
not require absolute separation of a DPS
from other members of its species,
because this can rarely be demonstrated
in nature for any population of
organisms (61 FR 4724; February 7,
1996). Our determination that the BayDelta longfin smelt meets the criteria of
a DPS was published in the April 2,
2012, Federal Register (77 FR 19756). In
the 2022 and 2024 SSA reports as well
as our proposed listing rule, we
identified and considered more recent
research and reaffirmed that the BayDelta longfin smelt is a valid DPS (87 FR
60958–60959; October 7, 2022); Service
2022, p. 10; Service 2024, p. 10). Studies
that have examined longfin smelt
genetics have all found evidence that
the Bay-Delta population is distinct
from other northern populations (Israel
and May 2010, p. 230; Sağlam et al.
2021, p. 1793).
We acknowledge that Sağlam et al.
(2021) found evidence of northern
dispersal of some individuals from the
Bay-Delta population, as evidenced by
some shared genetic structure with
smaller populations in Northern
California estuaries and the Columbia
River. However, the study detected no
significant gene flow from any northern
estuaries southward into the Bay-Delta
population, suggesting gene flow is
unidirectional in a northerly fashion.
These findings suggest the Bay-Delta
population is genetically isolated, as it
does not appear to be receiving
immigrants from any northern
populations. Sağlam et al. (2021, pp.
1793, 1802) concluded that the BayDelta population was distinct and is
likely an important source for
maintaining nearby populations.
A recent study published after the
2022 SSA report examined other, much
smaller, longfin smelt populations along
the California coast (Brennan et al. 2022,
entire). The authors determined that
estuaries in proximity of the San
Francisco Bay estuary may not be
permanently inhabited by longfin smelt,
and that the Bay-Delta population may
therefore lack the resilience typically
provided by metapopulations. The
authors also noted that abundance and
distribution of longfin smelt appears to
have declined in other estuaries along
the California coast (Brennan et al. 2022,
p. 12). This information may further
support the hypothesis that reduction of
the Bay-Delta longfin smelt abundance
decreases the DPS’s contribution to
outside populations.
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Population Viability Analysis
(14) Comment: We received
comments expressing numerous
concerns regarding our population
viability analysis (PVA) and its use of
population survey indices rather than
actual abundance estimates for our
determination of the status for the BayDelta longfin smelt. Specifically, the
commenters took issue that the PVA
relies on population indices data, which
they contend do not fully sample the
entire water column or habitat strata
and introduce too much uncertainty on
the size of the population. The
commenters state that, because of these
issues, the Service may have
underestimated the size of the
population and therefore overestimated
the impact of threats facing the DPS;
and the Service cannot use the PVA to
determine time of extinction or base a
listing decision on such uncertain data.
Our response: As we described in the
2022 and 2024 SSA reports (Service
2022, appendix B, pp. 111–123; Service
2024, appendix B, pp. 115–128), exact
population abundance information is
not necessary. A count-based PVA can
be applied to index values, where a
population index represents some
portion of the total population as long
as the proportion of the population that
is observed remains relatively constant
over time (Morris and Doak 2002, p. 51).
General interpretation of the abundance
indices for longfin smelt or any other
species also requires this assumption or
a correction for major deviations or
inconsistencies. In the SSA reports, we
acknowledge the different limitations of
the long-term surveys and utilize them
collectively to reduce potential biases
that may be present in any single
survey. As we state in our description
of the methods used to conduct the PVA
(Service 2022, appendix B, pp. 111–123;
Service 2024, appendix B, pp. 115–128),
we incorporated and applied our
analysis in the PVA using several
datasets that index the abundance of
Bay-Delta longfin smelt, and these data
capture the landscape of the available
information regarding the estimation of
abundance for the DPS.
In our review of the status of the BayDelta longfin smelt, we used all the best
commercial and scientific information
available to make our determination.
The PVA was just one of the many tools
we used in our analysis. We consider
the PVA to be one of many appropriate
tools that provide useful information for
our decision on the listing status of the
DPS. PVAs are best suited to test a range
of possible conditions or demographic
assumptions to provide a range of likely
fates for a population (Morris et al.
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1999, p. 2). We conducted sensitivity
analyses to examine the effects of
different potential starting population
sizes and different minimum viable
population sizes (quasi-extinction
thresholds). The sensitivity analyses
showed that in most demographic
scenarios tested, the population is at a
high risk of quasi-extinction in the near
future (Service 2024, figures 3 & 4, pp.
121 and 122). It is noteworthy that the
count-based PVA presented in appendix
B predicts the time to quasi-extinction
under current environmental conditions
and does not account for the worsening
environmental conditions associated
with increases in drought intensity or
frequency, warming water temperatures,
and sea-level rise that are occurring and
are predicted to continue.
(15) Comment: Some public
commenters noted that the metaanalysis was conducted on multiple
surveys and as a result obscured data
from the San Francisco Bay study ottertrawl (SFBS OT) age-1 survey. The
commenters stated that the mean
population growth rate for the SFBS OT
age-1 survey estimated in the PVA
indicated a trend of increasing
abundance and therefore is inconsistent
with the Service’s finding that the DPS
is currently in danger of extinction.
Our response: In an effort to include
all available data and produce the best
estimates of population growth rates, a
meta-analysis was performed using all
surveys. The meta-analysis presented in
appendix B of the 2022 and 2024 SSA
reports (a method proposed by a
reviewer of the 2021 SSA report)
illustrates how pooling information
from the full suite of available survey
data can help reduce uncertainty in our
overall estimate of the mean population
growth rate. Two important features of
a meta-analysis are that the meta-mean
will be closer to the population mean on
average than any of the individual
surveys (sample means) and the
confidence interval will be narrower,
making it a more precise estimator of
the population mean than the estimates
from the samples.
Based on review and comment of the
meta-analysis (Service 2022, appendix
B, pp. 111–123), we revised our
methods slightly for estimating mean
population growth rates for the DPS. As
a result of this modification, we
obtained different estimates for each
survey than were reported in the 2022
SSA report (Service 2022, appendix B,
p. 120). Results indicate that all of the
abundance indices show long-term
population declines, and all except for
the SFBS age-0 otter trawl are
statistically significant downward
trends (Service 2024, appendix B, table
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2). In both the original and revised
analyses, seven of the eight surveys
examined indicate a negative mean
growth rate. To exclude evidence from
all seven other surveys and base our
decision off the single potentially
positive survey time series would
sacrifice a substantial volume of
available data and bias the results of the
analysis.
(16) Comment: Several commenters
stated that the 2022 SSA report and
proposed rule indicate confirmation
bias by relying on data from the FMWT
survey without acknowledging the
limitations of those data or evaluating
competing data from the SFBS OT age1 survey, which indicates that Bay-Delta
longfin smelt DPS abundance is not
declining. They further state that the
FMWT survey should not be used as the
primary determinant due to its limited
extent in areas surveyed and that it may
underrepresent the abundance of the
DPS due to its sampling methods.
Our response: In the 2022 and 2024
SSA reports, we do not rely on the
FMWT data any more than any other
survey and acknowledge limitations of
all available surveys within the estuary
(Service 2022, pp. 107–109; Service
2024, pp. 108–110). As stated above, we
utilized information from the entire
suite of surveys including the SFBS OT.
As previously discussed, the
commenter’s statement that the SFBS
OT data imply that the DPS is not
declining is not supported by analyses
of those data (Tobias et al. 2023, entire).
In the SSA reports, we acknowledge
that the FMWT does not sample the
entire range of Bay-Delta longfin smelt
during the fall; however, the survey
does sample all of the low-salinity zone
and some of the mesohaline water west
of the low-salinity zone when Bay-Delta
longfin smelt return to the upper estuary
in the fall and early winter (Service
2022, pp. 43–46; Service 2024, pp. 43–
47). Research on the Bay-Delta longfin
smelt has found that a significant
proportion of age-0 (fish younger than 1
year of age) and older individuals
inhabit the low-salinity zone prior to
and during spawning, making FMWT
sampling in this region a reasonable
index for population abundance
(Rosenfield and Baxter 2007, p. 1590).
We also acknowledge that the FMWT
does not specifically target benthic
habitat; however, except for a few
particularly deep sampling stations, fish
within a geographic location can still be
sampled by the FMWT whether they are
in the middle or the bottom of the water
column (Service 2022, p. 44; Service
2024, p. 44). The ability of the FMWT
to track changes in the DPS population
is evidenced by its high correlation with
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SFBS data (Rosenfield and Baxter 2007,
p. 1590). Ultimately, both the FMWT
and SFBS OT surveys use their own
standardized methods that are capable
of indexing changes in relative
abundance.
(17) Comment: One commenter
pointed to the increase of FMWT
abundance indices in the years of 2021–
2022 as evidence of population
resilience and stated that the Service
needs to evaluate this information.
Our response: In our 2022 SSA report,
we included analyses of the 2021
FMWT abundance indices (Service
2022, appendix B, p. 119) and
considered this information in our
proposed rule to list the Bay-Delta
longfin smelt. Because the 2022 index
was calculated after we had concluded
our analyses and published our
proposed rule, we reviewed the 2022
indices in making our final
determination. The Bay-Delta longfin
smelt population has historically had
highly variable population growth and
declines, and such short-term
population changes are not unexpected
based on the trend information over the
full FMWT survey effort (Service 2024,
p. 47). Similar increases in abundance
have occurred in 2000, 2006, 2011,
2013, and 2017; however, all of these
increases resulted in abundance
estimates that are well below those prior
to the declines experienced in the 1980s
when population numbers were several
orders of magnitude greater than those
currently experienced by the DPS.
(18) Comment: Several comments
point to the wide confidence intervals of
estimated growth rates in the countbased PVA and interpret these intervals
as evidence that the Bay-Delta longfin
smelt population may be stable or
increasing.
Our response: The commenters are
correct in their interpretation of the
confidence intervals around the mean
growth rates for individual surveys.
Bay-Delta longfin smelt population
growth rates are highly variable from
year to year depending on prevailing
environmental conditions and spawning
stock size. The wide confidence
intervals are a result of this variation
where in some years the population
grows even though in most years it
declines. To account for this variability
and differences in confidence intervals
of the studies, we developed the metaanalysis to pool estimates of the
population growth rates from the
individual surveys to get a more precise
estimate. Based on the overall
population trend over the length of all
the studies, we determined that the BayDelta longfin smelt population is in
decline.
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(19) Comment: One commenter
provided a technical review of the
analyses presented in the appendices of
the 2022 SSA report and stated the
information presented in appendix B
required additional documentation of
the evaluation of the assumptions,
reconsideration of how the analysis
accounts for sample error, and
comparisons of density-independent
and density-dependent formulations of
the models. In response, the commenter
provided their own meta-analysis
utilizing alternative methods to capture
uncertainty.
Our response: The analysis and text of
appendix B has gone through revisions
since the publication of the 2022 SSA
report and some of the points and
corrections identified by the commenter
have been addressed in our current SSA
report (Service 2024, appendix B).
Regarding the commenter’s alternative
analysis, we could not fully incorporate
it because the methods used are not
sufficiently described for us to fully
evaluate them. However, taking their
reported results at face value, an
increase in confidence limits would
suggest a less stable population growth
rate than was reported in the SSA
report. This scenario would tend to
produce a shorter time to quasiextinction, likely offsetting the small
increase in mean that they also report.
Therefore, we conclude that this
alternative analysis would also support
a conclusion that the DPS is at risk of
quasi-extinction.
Contemporary Versus Pre-Development
Outflow
(20) Comment: We received a
comment that there has been no
statistically significant reduction in
outflow throughout the winter-spring
period, nor on an annual basis when
comparing contemporary to predevelopment conditions. The
commenter also critiqued our use of
Reis et al. (2019) in the SSA report,
stating that the study failed to account
for evapotranspiration that occurred
prior to development in the estuary.
Our response: One study comparing
the pre-development conditions and
contemporary conditions of the Central
Valley and potential changes in the
annual average San Francisco Bay Delta
outflow found that the outflow has not
changed substantially (Fox et al. 2015,
pp. 4267–4271). However, annual
average San Francisco Bay Delta outflow
is not biologically relevant to Bay-Delta
longfin smelt. Contemporary water
operations have resulted in less San
Francisco Bay Delta outflow during the
winter and spring months and increased
outflow during the summer months
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(Hutton et al. 2017a, fig. 5, p. 2507;
Gross et al. 2018, fig. 4, p. 10). Winter
and spring months are when Bay-Delta
longfin smelt in the estuary spawn and
larvae rear in the low-salinity zone, and
reduced outflow in the winter and
spring months has been repeatedly
linked to reduced juvenile Bay-Delta
longfin smelt production (Stevens and
Miller 1983, pp. 431–432; Jassby et al.
1995, p. 285; Kimmerer 2002, p. 47;
Rosenfield and Baxter 2007, p. 1585;
Sommer et al. 2007, p. 274; Kimmerer
et al. 2009, p. 381; MacNally et al. 2010,
p. 1422; Thomson et al. 2010, pp. 1439–
1440; Maunder et al. 2015, p. 108;
Nobriga and Rosenfield 2016, p. 53;
Kimmerer and Gross 2022, fig. 2, p.
2735). The reductions in February,
April, and May outflows have been
primarily attributed to reductions in San
Francisco Bay Delta outflow as a result
of water diversions (Hutton et al. 2017b,
table 3, p. 2523).
We do not agree with the commenter’s
critique of Reis et al. (2019). Differences
in evapotranspiration rates are primarily
a concern when comparing predevelopment and post-development
outflows in the estuary because
extensive wetlands and floodplains predevelopment theoretically increased
evapotranspiration (reducing San
Francisco Bay Delta outflow), but levees
constructed during development largely
disconnected floodplains and resulted
in decreased evapotranspiration. By
1930, almost the entire San Francisco
Bay Delta had been leveed and
reclaimed (Whipple et al. 2012, p. 25).
Reis et al. (2019) examined the years
1930–2018 when no substantial changes
in estuary evapotranspiration occurred.
As a result, the authors were able to
reasonably assess the relative impact of
water operations on San Francisco Bay
Delta outflows.
Underestimate of Threats
(21) Comment: One commenter stated
that the Service understated the risk to
the DPS by not considering specific
current proposals to increase diversions
of freshwater from the San Francisco
Bay estuary and its watershed and that
if realized these projects could result in
changes to outflow in the estuary and
further impact the Bay-Delta longfin
smelt. The commenter points to several
proposed projects including the Delta
Conveyance Project, Sites Reservoir, and
the State Water Resources Control
Board’s voluntary agreement process.
Our response: In the 2022 SSA report
and proposed rule, we identified
reduced freshwater flow and diversion
as one of the primary threats driving the
current and future status of the BayDelta longfin smelt (Service 2022, pp.
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28–30; 71–73). In our analysis of future
conditions, we also acknowledged that
changes in water demand may be more
severe as the information used in our
analysis identified impacts only out to
the year 2030 due to the uncertainty and
difficulty in accurately identifying
changes with the necessary specificity
(Knowles et al. 2018, p. 7638). However,
due to the ongoing refinement of these
proposed projects a specific assessment
of each project was not possible within
the timeframe for completion of our
final rule. These projects, and any
attendant risk or benefits to Bay-Delta
longfin smelt, will be evaluated as they
are implemented through appropriate
regulatory processes, including section
7 consultations and/or section 10
permits, and future recovery planning
and implementation for the Bay-Delta
longfin smelt.
(22) Comment: One commenter stated
that neither the 2022 SSA report nor the
proposed rule evaluated the threat
posed by harmful algal blooms (HABs)
such as the one observed in the summer
of 2022.
Our response: We agree that in our
2022 SSA report and proposed rule, we
did not include HABs as a threat to the
Bay-Delta longfin smelt or a growing
stressor to fish populations in the
estuary. We agree that marine and
brackish water HABs, such as the bloom
that occurred in parts of San Francisco
Bay in 2022, could plausibly affect BayDelta longfin smelt individuals in
localized areas, but the impact of such
blooms on the DPS overall is not well
studied, and the best available
information to date does not support a
conclusion that HABs are a substantial
threat to the status of the DPS. However,
we agree that recent events are
concerning. As emerging threats are
defined and better understood, they will
inform future consultations, permits,
and recovery planning.
I. Final Listing Determination
Background
The longfin smelt is a small fish
species 9–11 centimeters (cm) (3.5–4.3
inches (in)) in length with a relatively
short lifespan of approximately 2 to 3
years. The Bay-Delta longfin smelt DPS
occupies the San Francisco Bay estuary
and areas of the Pacific Ocean out to the
Farallon Islands (see figure 1). A
thorough review of the taxonomy, life
history, and ecology of the Bay-Delta
longfin smelt is presented in the current
SSA report (Service 2024, pp. 6–23).
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San Francisco Bay-Delt~ Estuary
. Range of the San Franbisco Bay-Delta'tongfin Smelt
, r
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Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533)
and the implementing regulations in
title 50 of the Code of Federal
Regulations set forth the procedures for
determining whether a species is an
endangered species or a threatened
species, issuing protective regulations
for threatened species, and designating
critical habitat for endangered and
threatened species. On April 5, 2024,
jointly with the National Marine
Fisheries Service, the Service issued a
final rule that revised the regulations in
50 CFR part 424 regarding how we add,
remove, and reclassify endangered and
threatened species and what criteria we
apply when designating listed species’
critical habitat (89 FR 24300). On the
same day, the Service published a final
rule revising our protections for
endangered species and threatened
species at 50 CFR part 17 (89 FR 23919).
These final rules are now in effect and
are incorporated into the current
regulations. Our analysis for this final
decision applied our current
regulations. Given that we proposed
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listing this species under our prior
regulations (revised in 2019), we have
also undertaken an analysis of whether
our decision would be different if we
had continued to apply the 2019
regulations; we concluded that the
decision would be the same. The
analyses under both the regulations
currently in effect and the 2019
regulations are available on https://
www.regulations.gov.
The Act defines an ‘‘endangered
species’’ as a species that is in danger
of extinction throughout all or a
significant portion of its range, and a
‘‘threatened species’’ as a species that is
likely to become an endangered species
within the foreseeable future throughout
all or a significant portion of its range.
The Act requires that we determine
whether any species is an endangered
species or a threatened species because
of any 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;
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(D) The inadequacy of existing
regulatory mechanisms; or
(E) Other natural or manmade factors
affecting its continued existence.
These factors represent broad
categories of natural or human-caused
actions or conditions that could have an
effect on a species’ continued existence.
In evaluating these actions and
conditions, we look for those that may
have a negative effect on individuals of
the species, as well as other actions or
conditions that may ameliorate any
negative effects or may have positive
effects.
We use the term ‘‘threat’’ to refer in
general to actions or conditions that are
known to or are reasonably likely to
negatively affect individuals of a
species. The term ‘‘threat’’ includes
actions or conditions that have a direct
impact on individuals (direct impacts),
as well as those that affect individuals
through alteration of their habitat or
required resources (stressors). The term
‘‘threat’’ may encompass—either
together or separately—the source of the
action or condition or the action or
condition itself.
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However, the mere identification of
any threat(s) does not necessarily mean
that the species meets the statutory
definition of an ‘‘endangered species’’ or
a ‘‘threatened species.’’ In determining
whether a species meets either
definition, we must evaluate all
identified threats by considering the
species’ expected response and the
effects of the threats—in light of those
actions and conditions that will
ameliorate the threats—on an
individual, population, and species
level. We evaluate each threat and its
expected effects on the species, then
analyze the cumulative effect of all of
the threats on the species as a whole.
We also consider the cumulative effect
of the threats in light of those actions
and conditions that will have positive
effects on the species, such as any
existing regulatory mechanisms or
conservation efforts. The Secretary
determines whether the species meets
the definition of an ‘‘endangered
species’’ or a ‘‘threatened species’’ only
after conducting this cumulative
analysis and describing the expected
effect on the species.
The Act does not define the term
‘‘foreseeable future,’’ which appears in
the statutory definition of ‘‘threatened
species.’’ Our implementing regulations
at 50 CFR 424.11(d) set forth a
framework for evaluating the foreseeable
future on a case-by-case basis, which is
further described in the 2009
Memorandum Opinion on the
foreseeable future from the Department
of the Interior, Office of the Solicitor
(M–37021, January 16, 2009; ‘‘MOpinion,’’ available online at https://
www.fws.gov/library/collections/
national-listing-and-classificationguidance). The foreseeable future
extends as far into the future as the U.S.
Fish and Wildlife Service and National
Marine Fisheries Service (hereafter, the
Services) can make reasonably reliable
predictions about the threats to the
species and the species’ responses to
those threats. We need not identify the
foreseeable future in terms of a specific
period of time. We 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. In other words, the
foreseeable future is the period of time
over which we can make reasonably
reliable predictions. ‘‘Reliable’’ does not
mean ‘‘certain’’; it means sufficient to
provide a reasonable degree of
confidence in the prediction, in light of
the conservation purposes of the Act.
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Analytical Framework
The current SSA report documents
the results of our comprehensive
biological review of the best scientific
and commercial data available regarding
the status of the Bay-Delta longfin smelt,
including an assessment of the potential
threats to the DPS. The SSA report does
not represent our decision on whether
the DPS should be listed as an
endangered or threatened species under
the Act. However, it does provide the
scientific basis that informs our
regulatory decisions, which involve the
further application of standards within
the Act and its implementing
regulations and policies.
To assess the Bay-Delta longfin
smelt’s viability, we used the three
conservation biology principles of
resiliency, redundancy, and
representation (Shaffer and Stein 2000,
pp. 306–310). Briefly, resiliency is the
ability of the species to withstand
environmental and demographic
stochasticity (for example, wet or dry,
warm or cold years); redundancy is the
ability of the species to withstand
catastrophic events (for example,
droughts, large pollution events), and
representation is the ability of the
species to adapt to both near-term and
long-term changes in its physical and
biological environment (for example,
climate conditions, pathogens). In
general, species viability will increase
with increases in resiliency,
redundancy, and representation (Smith
et al. 2018, p. 306). Using these
principles, we identified the DPS’s
ecological requirements for survival and
reproduction at the individual,
population, and DPS levels, and
described the beneficial and risk factors
influencing the DPS’s viability.
The SSA process can be categorized
into three sequential stages. During the
first stage, we evaluated the individual
DPS’s life-history needs. The next stage
involved an assessment of the historical
and current condition of the DPS’s
demographics and habitat
characteristics, including an
explanation of how the DPS arrived at
its current condition. The final stage of
the SSA involved making predictions
about the DPS’s responses to positive
and negative environmental and
anthropogenic influences. Throughout
all of these stages, we used the best
available information to characterize
viability as the ability of the DPS to
sustain populations in the wild over
time. We use this information to inform
our regulatory decision.
The following is a summary of the key
results and conclusions from the current
Bay-Delta longfin smelt SSA report
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(Service 2024, entire); the full SSA
report can be found at Docket No. FWS–
R8–ES–2022–0082 on https://
www.regulations.gov.
Summary of Biological Status and
Threats
In this discussion, we review the
biological condition of the DPS and its
resources, and the threats that influence
the DPS’s current and future condition,
in order to assess the DPS’s overall
viability and the risks to that viability.
The needs of the Bay-Delta longfin
smelt can be categorized into three main
resource and biological condition
categories, and include: (1) appropriate
habitat salinity, by life stage; (2)
appropriate habitat temperature
conditions, by life stage; and (3)
adequate food resources and
availability, by life stage. As the BayDelta longfin smelt utilizes both
freshwater and saline water conditions
across its life cycle, its habitat is
extremely variable. These variable
conditions, along with other factors
including the interaction among these
dynamic variables, exert a strong
influence on habitat suitability across
space and time.
Bay-Delta longfin smelt have
temperature tolerances that impact the
volume and seasonality of suitable
habitat. It is logical to presume that the
Bay-Delta DPS, inhabiting as it does the
most southern portion of the species’
range, has historically been (and is) at
the uppermost temperature tolerance
range of the species. Larvae appear to be
adapted to cool water conditions. Larvae
inhabit water temperatures between 8
and 12 °C (46 and 54 °F) (Grimaldo et al.
2017, p. 8). Available research indicates
that temperatures approaching and
exceeding 15 °C (59 °F) impair larval
viability, and hence this benchmark
may be ecologically significant. At later
larval stages, longfin smelt are still
likely restricted to water temperatures
below 20 °C (68 °F) (Jeffries et al. 2016,
p. 1709). In general, age-1 and age-0 fish
inhabit 16–18 °C (61–64 °F) water in
summer and fall. Adults are thought to
be limited by water temperature >22 °C
(>72 °F) during the summer and likely
spend the majority of this time in cooler
Bay habitats and the open ocean (see
Service 2024, p. 25). Fish return to
spawn where water quality conditions
are favorable for egg survival. These
conditions vary in location depending
on Delta outflow, as well as flows from
Bay Area tributaries. Spawning occurs
at or below water temperatures of 13 °C
(55 °F), but has been documented at up
to 16 °C (61 °F) (see Service 2024, p. 25).
Bay-Delta longfin smelt have a
defined salinity tolerance range that
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increases as fish mature. This is
consistent with their anadromous life
history requiring spawning and early
rearing in fresher San Francisco Bay
Delta and Bay tributary waters. Yolk-sac
larvae survive the longest and grow the
largest at 5 and 10 parts per thousand
(ppth) and are able to maintain water
balance equally between 0.4 and 10
ppth, but the same lifestage is unable to
survive at 32 ppth (ocean salinity).
Yolk-sac larvae cannot complete yolk
resorption in freshwater. In field
surveys, peak yolk-sac larval densities
have been found at 2–4 ppth (Grimaldo
et al. 2017, p. 8), which is also
concordant with the early life salinities
that produce highest survival to later
life stages (Hobbs et al. 2010, p. 564).
The California Department of Fish and
Wildlife’s (CDFW) 20-mm surveys have
also shown peak larval distribution near
this same salinity zone (i.e., 2–4 ppth),
although larvae have been detected in
salinities as high as 12 ppth (see Service
2024, pp. 25–26). The 20-mm survey
gets its name from the size at which
Bay-Delta longfin smelt are retained and
readily identifiable at the fish facilities
associated with the State and Federal
pumping facilities.
Available data clearly indicate a very
strong association of Bay-Delta longfin
smelt to turbid water conditions.
Aquatic turbidity provides simultaneous
feeding and predator avoidance
advantages for larval fishes (Utne-Palm
2002, p. 115; Pangle et al. 2012, pp. 10–
11). Turbidity enhances prey avoidance
at detection distances typical of
predatory fish species. Further, the
sediment and algal particles often
backlight relatively translucent
zooplankton, helping larval fishes see
these prey more easily (Utne-Palm 2002,
p. 119). In contrast, larger fishes that
may prey on fish larvae have longer
search and reactive distances so more
sediment and algal particles are in
between these larger fish and their
potential prey (Utne-Palm 2002, pp.
122–123). We assume that these
turbidity mechanisms that apply
broadly to larval fishes also apply to
later life stages of Bay-Delta longfin
smelt. Taken together, recent laboratory
experiments, combined with field
results, provide an assessment of earlylife habitat needs favoring more turbid
conditions (Utne-Palm 2002, entire;
Pangle et al. 2012, entire).
Bay-Delta longfin smelt exhibit high
prey-specificity. During the time that
longfin smelt larvae and small juveniles
are feeding in low-salinity habitats, they
appear to focus on only two prey taxa.
Smaller larvae appear to primarily use
the copepod Eurytemora affinis as prey,
while larger larvae and small juveniles
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appear to require mysids as prey.
Longfin smelt pre-spawning adults in
Suisun Marsh have shown a strong
dietary preference for mysids, while
relying on copepods and amphipods
when mysids are scarce (see Service
2024, pp. 26–27). As longfin smelt
exhibit very little variation in prey use,
they are considered more susceptible to
food web changes than some other
fishes (Feyrer et al. 2003, p. 281). The
current SSA report (Service 2024, p. 27)
discusses some observations from
various studies regarding affects to the
low-salinity zone from invasion by the
overbite clam (Potamocorbula
amurensis) in the 1980s and potential
impacts to the Bay-Delta longfin smelt
as a food limitation stressor (see below,
and also Service 2024, pp. 35–37).
Threats Influencing the Bay-Delta
Longfin Smelt
The threats facing the Bay-Delta DPS
of the longfin smelt include habitat
alteration (Factor A) and changes to
hydrology associated with reduced and
altered freshwater flows (Factor A);
increased water temperatures (Factor A);
reduced food resource availability
(Factor E); predation (Factor C);
entrainment from freshwater diversion
facilities (Factor E); and contaminants
(Factor E). We consider reduced and
altered freshwater flows resulting from
human activities and impacts associated
with current climate change conditions
(increased magnitude and duration of
drought and associated increased
temperatures) as the main threat facing
the Bay-Delta longfin smelt due to the
importance of freshwater flows to
maintaining the life-history functions
and species needs of the DPS. However,
because the Bay-Delta longfin smelt is
an aquatic species and the needs of the
species are closely tied to freshwater
input into the estuary, the impact of
many of the other threats identified
above are influenced by the amount of
freshwater inflow into the system (i.e.,
reduced freshwater inflows reduce food
availability, increase water
temperatures, and increase entrainment
potential).
Reduced and Altered Freshwater Flows
The development of dams and water
delivery infrastructure built throughout
the Sacramento and San Joaquin River
basins for flood protection and water
supply for agriculture and human
consumption has greatly impacted
freshwater flows into the San Francisco
Bay estuary (Service 2024, section
3.1.1). The creation of this water storage
and delivery system, where water is
stored during the wet season and
conveyed to farms and cities during the
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61039
dry season, has resulted in one of the
largest human-altered water systems in
the world (Nichols et al. 1986, p. 569).
Operation of this system has resulted in
a broader, flatter hydrograph with less
seasonal variability, thus changing the
timing, magnitude, and duration of
freshwater flows into the San Francisco
Bay-Delta (Kimmerer 2004, p. 15;
Andrews et al. 2017, p. 72; Gross et al.
2018, p. 8). It is estimated that the
Federal and State water projects
annually reduce an average of about 5
million acre-feet (MAF) of freshwater
into the San Francisco Bay Delta, while
other municipal or private reservoirs or
diverters annually divert an additional 8
MAF of potential freshwater into the
San Francisco Bay Delta (Hutton et al.
2017b, fig. 4, p. 2523). The cumulative
effect of this annual average of about 13
MAF of freshwater supplies has resulted
in a long-term decline in freshwater
inflow into the estuary during the
period of February through June relative
to estimates of what flows would have
been available absent water
development (Gross et al. 2018, fig. 6, p.
12; Reis et al. 2019, fig. 3, p. 12). This
situation has further increased the
frequency of very low outflow years
that, prior to water development, would
have been very rare and associated only
with extreme drought (Reis et al. 2019,
fig. 3, p. 12).
From 1956 to the 1990s, water exports
(water removed from the San Francisco
Bay Delta as a result of State (State
Water Project) and Federal (CVP) water
projects) increased, rising from
approximately 5 percent of the Delta
freshwater inflow to approximately 30
percent of the Delta inflow (Cloern and
Jassby 2012, p. 7). By 2012, an estimated
39 percent of the estuary’s unimpaired
freshwater flow in total was either
consumed upstream or diverted from
the estuary (Cloern and Jassby 2012, p.
8). Water exports continue to the
present day and are expected to
continue in the future.
A reduction in freshwater flows into
the estuary influences and impacts the
location and function of the low-salinity
zone (spawning and rearing habitat for
longfin smelt). Freshwater inflow into
the estuary and other co-linear
indicators of wet versus dry conditions
during the winter and spring have been
statistically associated with recruitment
of larvae to the juvenile life stage of BayDelta longfin smelt (Service 2024,
section 3.1.1). Prior to large-scale water
exports and reduced freshwater flows,
the location of the low-salinity zone (as
represented by the 2 percent bottom
salinity position, known as X2) reached
the ≤55-km (≤34-mi) point in the estuary
(monthly averages from February
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through May) in about half of all years.
More recently the position of X2
reaching at least the 55-km (34-mi) point
occurred only very rarely as a result of
wet year conditions (Gross et al. 2018,
fig. 6, p. 12 and fig. 7, p. 13) (Service
2024, section 3.1.1). In the case of BayDelta longfin smelt, optimal growth and
rearing conditions (food and water
conditions (salinity, turbidity,
circulation patterns)), especially for
early life stage fish, is directly linked to
freshwater inflow to the estuary.
habitats following drought. These
drought conditions have exacerbated the
impact of reduced freshwater flows from
human activities and have been
attributed to accelerating the
establishment of the overbite clam
(Potamocorbula amurensis) (see
Reduced Food Resources and Pelagic
Organism Decline (POD), below) by
making saline water conditions more
available throughout areas typically
associated with more freshwater
(Carlton et al. 1990, pp. 90–91).
Drought Conditions
California’s precipitation patterns can
be extremely variable, and several years
of dry conditions have occurred over
numerous extended periods resulting in
varying levels of drought (California
Department of Water Resources (DWR)
2020, entire). Drought periods can be
characterized as having less freshwater
flow, as well as shorter duration and
lower magnitude of peak flows. The
current trend in drought conditions has
recently increased in frequency,
duration, and magnitude (Swain et al.
2018, pp. 427–433). Prior to the 21st
century, dry and critically dry years
occurred approximately 33 percent of
the time. However, since the year 2000,
the dry and critically dry year frequency
has increased to 43 percent. Based on
soil moisture reconstruction, the period
between 2000 and 2021 was probably
the driest 22-year period on record
(Williams et al. 2022, p. 1). As the
existing impacts from climate change
(i.e., warmer temperatures) increase
evapotranspiration in the watershed, the
aforementioned water supply needs can
exacerbate the magnitude of realized dry
conditions over and above these natural
patterns in precipitation and reduced
San Francisco Bay Delta freshwater
inflow.
Bay-Delta longfin smelt exhibit poor
survival and reproduction during
droughts (Thomson et al. 2010, pp.
1438–1446; Mahardja et al. 2021, pp. 9–
10). The survival of Bay-Delta longfin
smelt through their early life stages is
lower during dry conditions and higher
during wet conditions, as evidenced by
Bay-Delta longfin smelt abundance
indices nearly always declining sharply
during dry periods then rebounding
when wet weather returns (Mahardja et
al. 2021, pp. 9–10). However, such
recovery does not always occur after
each drought cycle, leading to lower
baseline numbers for the DPS (Moyle
2002, p. 237; Sommer et al. 2007, pp.
270–276). In addition, extended dry
years compound the negative impacts to
Bay-Delta longfin smelt as the DPS has
not shown an ability to quickly recover
and reoccupy upstream spawning
Habitat Alteration
Large-scale habitat alteration such as
channelization and dredging of streams
and bays, building of levees and canals,
and draining of wetlands has occurred
since the 1850s. The impacts of such inwater and adjacent upland habitat
alterations greatly affected and
continues to impact the bathymetry of
the estuary by collectively making the
estuary deeper and less
hydrodynamically connected to the
surrounding landscape (Andrews et al.
2017, fig. 5, p. 64). The altered
waterways create more space and
avenues for the incoming tides to bring
more saline water landward.
Specifically, landscape changes since
1850 are estimated to have resulted in
an average landward shift of X2 of over
3 km (2 mi) (Andrews et al. 2017, p. 68).
This change along with reductions in
freshwater input into the estuary (see
Reduced and Altered Freshwater Flows,
above) has caused a winter-spring
upstream (landward) shift of X2 on the
order of 10–20 km (6–12 mi). Taken
together, the landscape changes
discussed above and changes to the
estuary’s flow regime have changed how
mixing processes function, and thus
altered the habitat and food resource
opportunities available for the estuary’s
biota, including the Bay-Delta longfin
smelt.
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Water Temperature Alterations
As described in the Life History and
Biology section of the current SSA
report (Service 2024, section 2.4), BayDelta longfin smelt spawning occurs
within cool-water conditions below 16
°C (61 °F), while larvae and young
juveniles show a preference for
temperatures below 15 °C (59 °F) and 20
°C (68 °F), respectively. The embryonic
through early juvenile life stages are
when Bay-Delta longfin smelt are
believed to be most vulnerable to
warming temperatures because these
early life stages do not possess the
ability to migrate to the cooler waters of
central San Francisco Bay and the
coastal ocean due to limited motility
and increases in potential predation.
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Subadults and adults are thought to be
limited to water temperature below 22
°C (72 °F). Studies and datasets indicate
water temperatures in the San Francisco
Bay Delta commonly exceed 22 °C
(72 °F) during the summer (Vroom et al.
2017, p. 9904; data from California Data
Exchange Center, Central & Northern
California Ocean Observing System, and
U.S. Geological Survey (Blodgett et al.
2011, entire). Age-1 to age-3 individuals
should possess the capacity to move to
cooler waters during such times, making
them less vulnerable than larvae and
age-0 juveniles. However, climate
change is predicted to substantially
increase the number of days that water
temperatures are inhospitable to all life
stages, likely decreasing the duration of
suitable spawning and larval rearing
windows (Service 2024, section 4.2.2).
Reduced Food Resources
As discussed above and in the current
SSA report (Service 2024, section 3.1.2),
the Bay-Delta longfin smelt historically
limited their diet to a relatively small
number of crustacean meso- and
macrozooplankton taxa. Bay-Delta
longfin smelt larvae have diets
dominated by a copepod, Eurytemora
affinis, that is common in the lowsalinity zone during the spring (CDFW,
unpublished data). The two most
common prey taxa for larger longfin
smelt are epibenthic mysids and
amphipods (Burdi 2022, pers. comm.;
CDFW unpub. Diet Study Data). The
copepod E. affinis was also at one time
an important prey item for a now muchdepleted mysid species, Neomysis
mercedis (Knutson and Orsi 1983, p.
478), a prey species of juvenile and
adult Bay-Delta longfin smelt.
Since the 1970s, the Eurytemora
affinis population in the estuary has
been in decline, but beginning in the
late 1980s, the zooplankton community
for the San Francisco Bay estuary
started undergoing about a decade of
rapid change in species composition,
trophic structure, and utility for fish
production (Winder and Jassby 2011,
pp. 683–685; Kratina et al. 2014, p.
1070; Brown et al. 2016, p. 8). This
decline coincided with the rapid
invasion of the estuary by the nonnative
overbite clam (Carlton et al. 1990, pp. 81
and 85, fig. 3) and with an extended
drought in the Central Valley in the
period 1987–1994 (Rosenfield and
Baxter 2007, p. 1589).
The overbite clam is a filter feeder
that is thought to have diverted food
resources from the primary food sources
of, or fed directly on, the nauplii (first
larval stage) of common calanoid
copepods and resulted in their decline.
These native copepods are one of the
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main sources of prey of larval Bay-Delta
longfin smelt (Carlton et al. 1990, pp.
90–91; Kimmerer et al. 1994, p. 87;
Feyrer et al. 2003, pp. 284–286;
Rosenfield and Baxter 2007, p. 1589).
Mysids have experienced an over
tenfold decrease in abundance and
accounted for less than 4 percent of total
zooplankton biomass within the estuary
after 1994 (Winder and Jassby 2011, p.
684). In addition to lower abundance,
the average individual sizes of mysids
in the estuary have decreased over time,
with a species composition shift
towards Hyperacanthomysis
longirostris, an invasive species that
reaches maturity at a smaller mass than
Neomysis species (Hennessy 2011,
entire). Although Bay-Delta longfin
smelt consume these nonnative species,
they are not preferred and the change in
food resources most likely results in an
increased effort for the DPS to meet its
food resource needs.
To further exacerbate the impacts of
the change in food resources, the
decline of the Bay-Delta longfin smelt’s
historical prey base has not been
accompanied by a large change in prey
use by the DPS (Barros et al. 2019, p. 15;
Feyrer et al. 2003, p. 285). This finding
suggests that Bay-Delta longfin smelt
had formed strong predator–prey
interactions with their primary prey, a
hypothesis supported by empirical data
(MacNally et al. 2010, p. 1426). Because
the DPS exhibits very little variation in
prey use despite the reduction in
natural prey availability, they are
considered more susceptible to food
web changes than some other fishes
(Feyrer et al. 2003, p. 281). The decline
in food resources is likely affecting
juvenile and adult longfin smelt growth
and fitness as well as increasing the
effort needed to meet food resource
demands (Kimmerer and Orsi 1996, pp.
418–419; Feyrer et al. 2003, p. 281).
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Predation
In the proposed rule and 2024 SSA
report, we discussed the role predation
may play on individuals and various life
stages of the Bay-Delta longfin smelt
(see the 2024 SSA report and proposed
rule for additional information).
Because little information is available
on the exact predators of the Bay-Delta
longfin smelt or the impact predation
has on the status of the DPS, we do not
consider the impacts from predation to
be a primary driver, but we still include
this consideration as part of the
cumulative impact from all threats for
the DPS, especially during poor habitat
conditions when food is lacking.
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Entrainment
Freshwater diversion occurs
throughout the estuary through intake
structures for agricultural, municipal,
and environmental purposes and in
some cases may lead to entrainment of
Bay-Delta longfin smelt. Entrainment
occurs when the suction caused by
pumping water creates an opportunity
for fish to follow or be captured by the
flow of water and become trapped and
transported by the hydrodynamic
footprint of those diversions. This
entrainment may result in fish,
especially early-life-stage fish, being
killed or removed from the estuary. BayDelta longfin smelt can be entrained in
water exported by the major pumping
facilities in the South Delta (see Water
Project Exports, below) when adults and
commingling age-1 individuals move
upstream into the freshwater portions of
the San Francisco Bay Delta (CDFW
2020a, fig. 13, p. 53). Bay-Delta longfin
smelt larvae and small juveniles that are
either rearing or being tidally dispersed
landward of X2 can also be entrained
(CDFW 2020a, fig. 13, p. 53). During
periods of high freshwater flow into the
estuary, Bay-Delta longfin smelt (adults,
juveniles, and larvae) are much less
likely to be entrained by the major
pumping facilities in the South Delta
because the low-salinity zone is further
downstream (or seaward) of the San
Francisco Bay Delta. However, changes
to the estuary’s landscape (see Habitat
Alteration, above) have caused the tidal
flows to reach further into the Old and
Middle Rivers (Andrews et al. 2017, p.
66), which, as discussed below, may
further impact Bay-Delta longfin smelt
(see Water Project Exports, below).
Below we describe the types of
freshwater diversions and exports and
their impacts on Bay-Delta longfin
smelt.
Water Project Exports: The State of
California through the DWR and the
U.S. Bureau of Reclamation
(Reclamation) operate freshwater
diversion facilities and infrastructure
associated with the SWP and CVP,
respectively, which export fresh water
from the Delta. The operation of these
facilities can exert a strong influence on
regional hydrodynamics (Kimmerer and
Nobriga 2008, fig. 7, p. 12; Hutton et al.
2019, fig. 7, p. 11). That hydrodynamic
influence can result in the entrainment
of fish, sometimes from considerable
distances (Kimmerer 2008, p. 2, fig. 1,
p. 3). Several methods have been
implemented to limit and offset the
entrainment impacts at the SWP and
CVP facilities, including construction of
forebays (areas used to collect fish
before they enter the pumps), fish
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screens, gate systems (used to divert fish
away from pumps), and salvage
operations (active collection and
transport of fish back into the estuary).
In most years, Bay-Delta longfin smelt
have been collected (‘‘salvaged’’) in the
fish facilities that are in front of each
pumping plant. The salvage of fish is an
indicator that individuals are being
entrained by pumping of water at these
facilities and either being killed or
removed from the estuary. The peak of
salvage of age-1 and older Bay-Delta
longfin smelt typically occurred in
January (Grimaldo et al. 2009, fig. 5, p.
1262). These adult and age-1 fish likely
represented individuals searching for
spawning habitats and immature
individuals commingling with the
adults. The peak of salvage of age-0 fish
typically occurred in April or May as
larval fish reach sizes at which they
could be retained on the fish screens of
the CVP and SWP fish collection
facilities. However, it is likely some
larvae began to be entrained once they
started hatching in December or
January, but remained undetected until
about March, with salvage efficiency
increasing in April–May as the fish
grow larger.
It is possible that past entrainment
and loss of Bay-Delta longfin smelt may
have reached levels of concern (CDFW
2020a, fig. 10, p. 47). However, since
2009, the entrainment of longfin smelt
has not been substantial (Service 2024,
fig. 3.4), perhaps partly due to
monitoring and management of flows in
the Old and Middle Rivers (OMR)
between the Sacramento/San Joaquin
River confluence and the export
facilities. When net OMR flow is
positive, San Joaquin River water is
generally moving seaward through the
San Francisco Bay Delta and away from
the pumping facilities. The more net
negative OMR is flowing, the more the
water in the San Francisco Bay Delta is
moving back upstream toward the
pumping plants and the faster that water
is moving south, thereby increasing
entrainment potential. The additional
negative flow causes Sacramento River
water entering the northwest portion of
the San Francisco Bay Delta to be
diverted southward toward the pumping
facilities rather than seaward, which
allows saltier tidal flows to move further
toward the San Francisco Bay Delta.
In order to address and minimize
effects to federally listed fish species
(delta smelt (Hypomesus
transpacificus), chinook salmon
(Sacramento River winter-run and
Central Valley spring-run salmon
(Oncorhynchus tshawytscha), Central
Valley steelhead (Oncorhynchus
mykiss), and green sturgeon (Acipenser
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medirostris)), restrictions to pumping
and other water operations management
strategies have been implemented by the
DWR and Reclamation to limit negative
OMR flows and associated entrainment
through the section 7 process of the Act
(Service 2008, entire; National Oceanic
and Atmospheric Administration,
National Marine Fisheries Service
[NMFS] 2009, entire; Service 2019,
entire; NMFS 2019, entire). In addition,
the DWR has implemented similar
measures for State-listed species
(including longfin smelt) (CDFW 2009b
Incidental Take Permit (ITP), entire;
CDFW 2020b, ITP, entire).
The results of two different analytical
approaches using smelt larval survey
(SLS) data suggest that entrainment of
fish has not exceeded 3 percent since
2009 (Kimmerer and Gross 2022). Gross
et al. (2022) coupled particle tracking
modeling with the SLS data set and
found an upper 95 percent credible
interval of proportional entrainment
was 2.9 percent in the critically dry
winter of 2013 and nearly zero in the
wet winter of 2017. Kimmerer and Gross
(2022) analyzed all of the SLS data in
the period 2009–2020. Similarly, this
approach also found proportional
entrainment was unlikely to have
exceeded 3 percent (range = 0.5 to 2.9
percent) (Kimmerer and Gross 2022,
table 1). We interpret these findings, as
well as previously published
information (CDFW 2020a, entire), to
indicate that the OMR management
strategies in place since 2009 have been
an effective conservation strategy for
limiting the impact of entrainment and
its consequences for the Bay-Delta
longfin smelt. As a result, the best
information currently available
indicates that management actions for
operating water diversion facilities are
assisting in limiting entrainment
impacts for the Bay-Delta longfin smelt.
Contaminants
The San Francisco Bay estuary has
been identified as an impaired water
body due to it containing numerous and
persistent contaminant compounds
(California State Water Resources
Control Board 2018, appendix A). The
list of contaminant compounds
identified within the estuary includes
elemental contaminants or ‘metals’ (e.g.,
mercury and selenium), toxic organic
compounds (dioxins, furans,
polychlorinated biphenyls), and
pesticides (chlordane dieldrin, DDT).
Additional emerging contaminants of
concern include newer pesticides, flame
retardants, nutrients, naturally
occurring toxins, microplastics, and
pharmaceuticals and personal care
products (i.e., plastic microbeads, insect
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repellant, sunscreen, cosmetics, etc.)
(Klosterhaus et al. 2013, pp. 97–98, table
1; Sutton et al. 2017, entire). Ongoing
analysis of water in the San Francisco
Bay Delta suggests that on average 10
new synthetic organic pesticide
chemicals are detected every year
(California Department of Pesticide
Regulation 2020, dataset). Water
sampling in one study of the San
Francisco Bay Delta indicated the
presence of more than 50 chemical
compounds from a single 1-liter (L) (34ounce (oz)) water sample (Moschet et al.
2017, pp. 1557–1560).
The sources of contaminants include
discharge from municipal wastewater
treatment plants, agricultural outfalls,
stormwater runoff, anti-fouling paints
on boat and ship hulls, and direct
human application of pest and aquatic
plant control compounds (Service 2024,
section 3.1.6). Legacy contaminants in
the Bay-Delta (those from historical
loading, such as organochlorine
chemicals (e.g., DDT) from past
agricultural use and mercury from past
mining activity) have been shown to
persist in the environment and continue
to impact ecosystems and can
bioconcentrate through the food web,
posing additional health risks (Connor
et al. 2006, pp. 87–88; MarvinDiPasquale and Cox 2007, p. 2).
Regulation has reduced the use of some
contaminants, only to be replaced by
other more potent alternative watersoluble chemicals such as
neonicotinoids, which have additional
impacts on nontarget species such as
aquatic invertebrates and fish (Buzby et
al. 2020, pp. 15–21).
Field-based toxicity is difficult to
determine, as impacted fish are not
recovered in order to be examined (i.e.,
fish either die from direct exposure and
resulting disease, or are eaten). Risk of
exposure and effect, as determined by
comparison to other species (e.g., delta
smelt and the introduced inland
silverside (Menidia beryllina)),
potentially include direct effects on
development, growth, and reproduction;
impacts resulting from impairments to
bioenergetic demands; and impaired
locomotion, reducing feeding success,
which can lead to increased
susceptibility to predation, disease, and
entrainment (Brander et al. 2012, p.
2854; Connon et al. 2009, p. 12;
Hasenbein et al. 2014, p. 696; Jeffries et
al. 2015a, p. 17407; Jeffries et al. 2015b,
p. 55; Cole et al. 2016, p. 219;
DeCourten and Brander 2017, p. 2).
Pelagic Organism Decline (POD)
Between the years 2002 through 2004,
abundance indices for multiple fish
species within the San Francisco Bay
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estuary declined abruptly in what is
known as the pelagic organism decline,
or POD. Specifically, the POD referred
to a drop in survey catches of four fish
species (Bay-Delta longfin smelt, delta
smelt, striped bass (Morone saxatilis),
and threadfin shad (Dorosoma
petenense)) (Sommer et al. 2007, p.
273). The POD event is generally
recognized as a population step-decline
for numerous fish species in the estuary.
The coincident declines of multiple
species suggested a possible common
cause, but a single mechanism for
decline that applied to all four fish has
not been identified (MacNally et al.
2010, p. 1426; Thomson et al. 2010, pp.
1442–1443). As a result, researchers
have focused on multiple causes, from
habitat changes, reductions in
freshwater inflow, water diversions,
food resource changes, competition,
predation, and contaminants, as
contributing to the POD (Sommer et al.
2007, pp. 271–276; MacNally et al.
2010, p. 1418; Fong et al. 2016, pp. 20–
21). As outlined above, all of these
factors have been identified as threats
impacting the Bay-Delta longfin smelt to
varying degrees. Although the POD
event is not a threat in itself, but is
instead most likely a result of multiple
threats, the subsequently smaller DPS
population is more susceptible to poor
habitat conditions and has a reduced
capability of rebounding from lower
abundance years.
Bay-Delta Longfin Smelt Current
Condition
Current Abundance
Several long-term survey efforts have
been established for monitoring San
Francisco Bay estuary fish populations
including the Bay-Delta longfin smelt.
These established survey efforts include
the 20-mm survey, the SFBS, and the
FMWT. The 20-mm survey has been
conducted since 1995, and although it
does not produce an abundance index
for Bay-Delta longfin smelt, we adapted
the methods for the delta smelt
abundance index for the Bay-Delta
longfin smelt. Our methods and
information on how we adapted the
study information are outlined in the
current SSA report (Service 2024,
appendix B). The SFBS has sampled
low-salinity to fully marine waters of
the estuary using standardized sampling
methods since 1980. However, sampling
was more sporadic in the 1990s and
again in several recent years. The SFBS
samples near bottom as well as
midwater to surface-oriented fishes
(Feyrer et al. 2015, Fig. 5, p. 3614) and
provides separate abundance indices for
ages 0, 1, and 2+ Bay-Delta longfin
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smelt. The longest of these survey
efforts is the FMWT, which was
initiated in 1967 and has surveyed
pelagic waters from the Delta into San
Pablo Bay monthly from September
through December each year. The
FMWT captures mostly juvenile and
adult fish 50–150 mm (2–6 in) in length
and has been used to monitor the
abundance of sampled fish species since
the late 1970s (Stevens and Miller 1983,
pp. 431–432). In the case of Bay-Delta
longfin smelt, the FMWT samples adults
and juveniles, most likely those
returning from more marine
environments to low-salinity and
freshwater areas associated with
spawning. Similar abundance estimates
are reflected in the 20-mm survey,
SFBS, and other modeling efforts
(Service 2024, section 3.2.1).
Collectively, these survey efforts
encompass abundance estimates of all
life stages of the Bay-Delta longfin smelt
in the estuary.
Figure 2 identifies FMWT abundance
information for Bay-Delta longfin smelt
since its inception in 1967 with
61043
emphasis on the years 2000 to 2020. The
FMWT time series is an index of fish
numbers returning to spawn in the San
Francisco Bay Delta, which is an
indicator of abundance patterns as
observed over this relatively longer time
interval presented to give a simplified
visual presentation of overall
population trend during the last several
decades. A more detailed analysis of
overall trends and attendant risk is
discussed, below.
Bay-Delta Longtin Smelt Abundance Indices Through Time
3000
Ill
u 2500
C
m
u 2000
C
::::J
..a
1500
~
1000
<
~
LL
1i!l!lll
3IOO
201()
2020
Yillilr
500
0
2005
2010
2015
Year
Figure 2. San Francisco Bay-Delta longfin smelt abundance indices for the period 2000-2020 from the
fall midwater trawl survey. (Inset displays time series since 1967; source: adapted from California
Department of Fish and Wildlife 2021.)
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All the best available field surveys for
documenting long-term abundance
trends indicate Bay-Delta longfin smelt
numbers have substantially declined
over time, with current relative
abundance reflecting small fractions of
the species’ historical relative
abundance and representing a decline of
three to four orders of magnitude over
the course of available historical
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abundance records. Even considering
the small periodic increases in numbers
in occasional years in the most recent
survey results (past 20 years), the
general trend over time has been lower
highs and lower lows in abundance for
the DPS. This finding supports the
conclusion that abundance of all life
stages has declined substantially over
the course of several decades and that
the overall decline has continued in
recent years (Service 2024, section 3.2).
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A meta-analysis of annual population
growth rates derived from the
monitoring data showed that the DPS
has a negative population growth rate
(Service 2024, section 3.2.2). Figure 3
displays quasi-extinction risk
projections (including confidence
intervals) over time for the Bay-Delta
longfin smelt from our risk assessment
(Tobias et al. 2023, fig. 4, p. 7; Service
2024, appendix B).
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Population Trends and Risk of QuasiExtinction
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C?
.... .......- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2020 2025 2030 2035 2040 2045 2050 2055 2060 2065
Figure 3. Quasi-extinction risk projections {including confidence intervals} over time for the San Francisco
Bay-Delta longfin smelt. {Mean probability of quasi-extinction {solid line}, with bootstrapped 95 percent
confidence bands {dashed lines}. The wide, horizontal line {gray line} highlights a 20 percent probability of
quasi-extinction.}
Reduced and altered freshwater flows
into the estuary greatly impact the
physical and ecological processes
important to Bay-Delta longfin smelt
spawning and larval rearing habitat.
Reductions in freshwater flow reduce
the number of young that survive to
later reproduce. Reduced freshwater
flows also require the DPS to move
farther inland to find appropriate lowsalinity conditions for spawning and
rearing. Although management actions
to limit the impact of water diversions
at export facilities have been
implemented, this movement farther
inland makes the DPS’s larvae and
young more vulnerable to entrainment
as a result of water diversion from water
export facilities.
The amount of freshwater input into
the estuary is dependent on natural wet/
dry precipitation patterns. These
patterns have been influenced by the
effects of current climate change
conditions, which have resulted in more
frequent, prolonged, and intense
drought conditions (reduced flows) and
increased water temperatures (poor
habitat conditions). Freshwater flows
into the estuary have also been greatly
influenced by human-caused alteration
of rivers and streams leading into the
estuary as well as diversion and export
of freshwater from the estuary. These
human-caused impacts of water
management have exacerbated the
impacts of environmental variability of
natural wet/dry precipitation patterns.
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In addition to altered habitat
conditions for the Bay-Delta longfin
smelt, the available food resources for
the DPS have also been severely
impacted. A rapid change to the
zooplankton community in the estuary
beginning in the late 1980s along with
the introduction of the nonnative
species such as the overbite clam and
others has greatly reduced the natural
prey base for the DPS and replaced it
with a smaller nonnative mysid.
Because the fish in the DPS continue to
exhibit very little variation in prey use
despite the reduction in natural prey
availability, they are considered more
susceptible to food web changes than
some other fishes. The decline in food
resources is likely affecting juvenile and
adult longfin smelt growth and fitness
as well as increasing the effort needed
to meet food resource demands.
After the review of the threats of
predation, entrainment, and
contaminants, we have determined that
they are not primary driving factors
currently influencing the Bay-Delta
longfin smelt. However, these threats
are likely still contributing cumulatively
to the overall impacts acting on the DPS.
We note that, by using the SSA
framework to guide our analysis of the
scientific information documented in
the SSA report, we have analyzed the
cumulative effects of identified threats
and conservation actions on the species.
To assess the current and future
condition of the species, we evaluate the
effects of all the relevant factors that
may be influencing the species,
including threats and conservation
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efforts. Because the SSA framework
considers not just the presence of the
factors, but to what degree they
collectively influence risk to the entire
species, our assessment integrates the
cumulative effects of the factors and
replaces a standalone cumulative-effects
analysis.
Resiliency, Redundancy, and
Representation for the Bay-Delta
Longfin Smelt
In the current SSA report for the BayDelta longfin smelt (Service 2024,
chapter 3), we evaluated the Bay-Delta
longfin smelt’s resiliency, redundancy,
and representation under our SSA
framework (Service 2016, entire).
Resiliency describes the ability of a
species to withstand stochastic
disturbance. Because the Bay-Delta
longfin smelt is a single, intermixed
population, we did not identify multiple
resiliency units but looked at the
population as a whole. As discussed
above, the Bay-Delta longfin smelt is
subject to multiple interacting threats,
including saltwater intrusion and
reduced freshwater flows, that are
altering and degrading habitat
conditions. The resulting impact of
these threats limits the extent, duration,
and availability of appropriate habitat
conditions needed for spawning,
rearing, and ultimate recruitment of
individuals into the population. These
threats include anthropogenic actions
(such as freshwater management,
freshwater diversion, and physical
alterations to the bathymetry of the
estuary) or poor or altered
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Effects of Threats Impacting the BayDelta Longfin Smelt
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environmental conditions (such as
increased frequency and magnitude of
drought resulting from current climate
change conditions). Disruptions to the
estuary’s food web associated with
reductions in freshwater flow or
introductions of nonnative species are
also limiting resiliency for the DPS.
Redundancy is the ability of a species
to withstand catastrophic events. The
Bay-Delta longfin smelt is a single
intermixed population and occurs in
areas within the San Francisco Bay
estuary as dictated by the extremely
modified and altered habitat and
resource conditions. The San Francisco
Bay estuary is also subject to extreme
environmental variability as a result of
climate change conditions resulting in
increased temperatures and frequency,
magnitude, and duration of drought. As
a result of these changes, the ability of
the system and organisms within the
estuary to withstand catastrophic events
and rebound during periods of more
favorable conditions is greatly reduced.
Large-scale estuary-wide ecosystem
population collapses of fish and native
zooplankton have occurred in the
estuary. Although no single cause for
the collapses has been identified, both
native and nonnative fish populations
have not recovered. The result has been
step-declines of the Bay-Delta longfin
smelt population size since the mid1980s, thereby reducing the redundancy
of the DPS.
Representation describes the ability of
a species to adapt to changing
environmental conditions over time.
This definition includes the ability of a
species to adapt to both near-term and
long-term changes in its physical and
biological environments. The Bay-Delta
longfin smelt population occurs in the
San Francisco Bay estuary and is a
single, genetically indistinguishable
population. The Bay-Delta longfin smelt
represents the southern extent of the
species as a whole and most likely is a
source for populations along the coast
north of San Francisco Bay, but the
number of individuals contributing to
populations further north has
substantially declined. Due to ocean
currents and the species’ poor
swimming capability, populations north
of the San Francisco Bay are unlikely to
have the ability to move south and assist
in reestablishing a population in the San
Francisco Bay-Delta once they have
been extirpated from the San Francisco
Bay-Delta. The DPS’s ability to adapt
behaviorally to environmental changes
(to have adaptive capacity) is also
limited. This limitation is exemplified
by the DPS’s behavioral tendency of not
adapting to food resource changes. As
discussed, food resources for the DPS
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have changed significantly yet the DPS’s
behavior has not shifted to adapt to
those changes.
In our evaluation of the current
condition of the Bay-Delta longfin smelt,
we evaluated several population
viability analyses (PVAs) that
quantitatively derive probabilities of
extinction over time based on the DPS’s
historical and current abundance
estimates (Service 2024; appendix B).
The PVAs used information from the
existing suite of surveys, including the
FMWT, the 20-mm survey, and the
SFBS (Service 2024, figure 3.11). The
PVAs modeled extinction probability
based on a continuation of existing
threats currently facing the DPS under
varying levels of population
recruitment. Population growth rates
were further synthesized by conducting
a meta-analysis on the growth rates of
the different surveys. The results of the
count-based PVA meta-analysis
identified that the probability of quasiextinction for the Bay-Delta longfin
smelt is estimated at 33 percent over 20
years and reaches 50 percent in 30 years
(Service 2024, appendix B).
As a result of our review of the best
scientific and commercial data available
on the Bay-Delta longfin smelt, we have
determined that the DPS’s resiliency is
low. Numerous decades of declining
abundance indices for the Bay-Delta
longfin smelt document the inability of
the DPS to rebound during more
favorable environmental conditions and
respond to the threats it is facing in the
contemporary San Francisco Bay
estuary. The Bay-Delta longfin smelt
also has extremely limited redundancy
because it effectively represents a single,
small population inhabiting the San
Francisco Bay-Delta and nearshore
ocean environment, and because it
continues to be impacted by large-scale
stochastic events and is subject to
catastrophic events. We have
determined that the representation of
the Bay-Delta longfin smelt is limited as
well, reflecting that same declining
abundance trend and no discernible and
quantifiable compensatory adaptation to
current ecological conditions. Based on
our evaluation of the current resiliency,
redundancy, and representation for the
Bay-Delta longfin smelt, we conclude
the current ability of the DPS to
maintain populations in the wild is low.
Future Conditions
As part of the SSA, we also developed
future-condition scenarios to capture
the range of uncertainties regarding
future threats and the projected
responses by the Bay-Delta longfin
smelt. To assess the future condition of
the Bay-Delta longfin smelt, we used
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published information related to the
varying environmental conditions of the
San Francisco Estuary, including future
climate change information and
projected increases in water demand,
and how these changes may impact how
well the estuary can support the BayDelta longfin smelt into the future. In
our analyses, we considered two
plausible future scenarios based on
representative concentration pathways
(RCP) 4.5 and 8.5 as the bookends for
our analysis. The scenarios assessed
climate change information
(temperature increases, changes in
precipitation patterns, sea-level rise)
through 2100, as published information
was available. The information
identified that declines in Bay-Delta
longfin smelt population abundance
will continue into the future under both
the RCP 4.5 and 8.5 scenarios. Because
we determined that the current
condition of the Bay-Delta longfin smelt
was consistent with an endangered
species (see Determination of the BayDelta Longfin Smelt’s Status, below), we
are not presenting the results of the
future scenarios in this final rule. Please
refer to the current SSA report (Service
2024, chapter 4) for the full analysis of
future scenarios.
Conservation Efforts and Regulatory
Mechanisms
Numerous efforts have been initiated
regarding conservation and regulation of
the San Francisco Bay estuary and its
resources, including managing water
flows into and export from the estuary,
improving water quality, conducting
habitat restoration, and implementing
measures or regulations to protect native
fish. This effort includes establishment
of multiagency collaborations such as
the Interagency Ecological Program
(IEP), which focuses on coordinating
and prioritizing science needs and
research to meet responsibilities under
State and Federal regulatory
requirements (IEP 2014, entire).
The State of California listed the
longfin smelt in the San Francisco Bay
estuary and along the California Coast as
a threatened species under the
California Endangered Species Act in
2009 (CDFW 2009a, entire; California
Natural Diversity Database 2022, entire)
and has issued restrictions and
requirements for the export of water for
the State Water Project (see
Entrainment, Water Project Exports,
above). Several other fish species (delta
smelt, several salmonid species) are
listed under both the Act and the
California Endangered Species Act, and
the Service and NMFS have also issued
biological opinions regarding the effects
to these species and their habitats for
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delivery and export of water from the
estuary (see Entrainment, Water Project
Exports, above). The State Water Board
is responsible for issuing water quality
standards and monitors contaminants
within the estuary (see Contaminants,
above). However, despite efforts such as
those identified above, the current
condition of the estuary and continued
threats facing the estuary and Bay-Delta
longfin smelt, such as reduced
freshwater inflow, severe declines in
population size, and disruptions to the
DPS’s food resources, have not been
ameliorated.
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Determination of the Bay-Delta Longfin
Smelt’s Status
Section 4 of the Act (16 U.S.C. 1533)
and its implementing regulations (50
CFR part 424) set forth the procedures
for determining whether a species meets
the definition of an endangered species
or a threatened species. The Act defines
an ‘‘endangered species’’ as a species in
danger of extinction throughout all or a
significant portion of its range and a
‘‘threatened species’’ as a species likely
to become an endangered species within
the foreseeable future throughout all or
a significant portion of its range. The
Act requires that we determine whether
a species meets the definition of
endangered species or threatened
species because of any 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.
Status Throughout All of Its Range
The Bay-Delta longfin smelt’s current
abundance and density throughout the
San Francisco Bay estuary have
substantially declined. Currently, the
DPS exists in very low abundance
despite periods when appropriate
habitat conditions, which typically
would allow for population rebounds,
are available. The best scientific and
commercial information available and
our analysis of that information revealed
that several threats are causing or
contributing to this decline and
currently pose a meaningful risk to the
viability of the DPS. These threats have
put the Bay-Delta longfin smelt largely
into a state of chronic population
decline due to habitat loss (reduction in
freshwater flows into the estuary),
which is exacerbated by limited food
resources and the impacts associated
with climate change, thereby limiting its
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resiliency and ability to withstand
catastrophic events (reduced
redundancy). This decline in numbers
of the Bay-Delta longfin smelt is also a
reflection of the DPS’s ability to adapt
to the ecosystem changes.
As a result of the DPS’s poor
performance in adapting to the suite of
stressors acting upon it, we consider the
Bay-Delta longfin smelt’s adaptive
capacity and, therefore, its current
representation to be low. The Bay-Delta
longfin smelt’s continued reduced
population size makes the DPS
vulnerable to varying habitat conditions
from year to year due to both
anthropogenic and environmental
conditions that are being influenced by
the effects of climate change.
Historically, with a larger population
size, the DPS was more resilient to such
stochastic and catastrophic events due
to its ability to rebound in abundance
when habitat conditions and resources
would allow. The habitat changes,
limitations to food resources, and
resulting small population size now
limit the DPS’s ability to maintain its
current population.
After evaluating threats to the DPS
and assessing the cumulative effect of
the threats under the section 4(a)(1)
factors, we find that the threats facing
the San Francisco Bay-Delta DPS of the
longfin smelt are current and ongoing
and include habitat degradation and
loss from reduced freshwater flow into
the estuary (Factor A), increased
intrusion of saltwater into spawning
habitat areas (Factor A), alteration of
food resources and availability (Factor
E), nonnative species competition and
food resource effects (Factor E), and the
effects associated with climate change
such as increased temperatures and
frequency, magnitude, and duration of
drought (Factor E). Because these threats
are ongoing and currently impacting the
DPS, and have already been shown to
have caused a significant decline in the
DPS’s current resiliency, redundancy,
and representation, the DPS meets the
Act’s definition of endangered status.
Thus, after assessing the best
scientific and commercial information
available, we determine that the San
Francisco Bay-Delta DPS of the longfin
smelt is in danger of extinction
throughout all of its range.
Status Throughout a Significant Portion
of Its Range
Under the Act and our implementing
regulations, a species may warrant
listing if it is in danger of extinction or
likely to become so in the foreseeable
future throughout all or a significant
portion of its range. We have
determined that the San Francisco Bay-
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Delta DPS of the longfin smelt is in
danger of extinction throughout all of its
range and accordingly did not undertake
an analysis of any significant portions of
its range. Because the San Francisco
Bay-Delta DPS of the longfin smelt
warrants listing as endangered
throughout all of its range, our
determination does not conflict with the
decision in Center for Biological
Diversity v. Everson, 435 F. Supp. 3d 69
(D.D.C. 2020), because that decision
related to significant portion of the
range analyses for species that warrant
listing as threatened, not endangered,
throughout all of their range.
Determination of Status
Our review of the best scientific and
commercial information available
indicates that the San Francisco BayDelta DPS of the longfin smelt meets the
definition of an endangered species.
Therefore, we are listing the San
Francisco Bay-Delta DPS of the longfin
smelt as an endangered species in
accordance with sections 3(6) and
4(a)(1) of the Act and our February 7,
1996, policy regarding distinct
population segments (61 FR 4722).
Available Conservation Measures
Conservation measures provided to
species listed as endangered or
threatened species under the Act
include recognition as a listed species,
planning and implementation of
recovery actions, requirements for
Federal protection, and prohibitions
against certain practices. Recognition
through listing results in public
awareness, and conservation by Federal,
State, Tribal, and local agencies, foreign
governments, private organizations, and
individuals. The Act encourages
cooperation with the States and other
countries and calls for recovery actions
to be carried out for listed species. The
protection required by Federal agencies,
including the Service, and the
prohibitions against certain activities
are discussed, in part, below.
The primary purpose of the Act is the
conservation of endangered and
threatened species and the ecosystems
upon which they depend. The ultimate
goal of such conservation efforts is the
recovery of these listed species, so that
they no longer need the protective
measures of the Act. Section 4(f) of the
Act calls for the Service to develop and
implement recovery plans for the
conservation of endangered and
threatened species. The goal of this
process is to restore listed species to a
point where they are secure, selfsustaining, and functioning components
of their ecosystems.
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The recovery planning process begins
with development of a recovery outline
made available to the public soon after
a final listing determination. The
recovery outline guides the immediate
implementation of urgent recovery
actions while a recovery plan is being
developed. Recovery teams (composed
of species experts, Federal and State
agencies, nongovernmental
organizations, and stakeholders) may be
established to develop and implement
recovery plans. The recovery planning
process involves the identification of
actions that are necessary to halt and
reverse the species’ decline by
addressing the threats to its survival and
recovery. The recovery plan identifies
recovery criteria for review of when a
species may be ready for reclassification
from endangered to threatened
(‘‘downlisting’’) or removal from
protected status (‘‘delisting’’), and
methods for monitoring recovery
progress. Recovery plans also establish
a framework for agencies to coordinate
their recovery efforts and provide
estimates of the cost of implementing
recovery tasks. Revisions of the plan
may be done to address continuing or
new threats to the species, as new
substantive information becomes
available. The recovery outline, draft
recovery plan, final recovery plan, and
any revisions will be available on our
website as they are completed (https://
www.fws.gov/program/endangeredspecies), or from our San Francisco BayDelta Fish and Wildlife Office (see FOR
FURTHER INFORMATION CONTACT).
Implementation of recovery actions
generally requires the participation of a
broad range of partners, including other
Federal agencies, States, Tribes,
nongovernmental organizations,
businesses, and private landowners.
Examples of recovery actions include
habitat restoration (e.g., restoration of
native vegetation), research, captive
propagation and reintroduction, and
outreach and education. The recovery of
many listed species cannot be
accomplished solely on Federal lands
because their range may occur primarily
or solely on non-Federal lands. To
achieve recovery of these species
requires cooperative conservation efforts
on private, State, and Tribal lands.
Once this species is listed, funding for
recovery actions will be available from
a variety of sources, including Federal
budgets, State programs, and cost-share
grants for non-Federal landowners, the
academic community, and
nongovernmental organizations. In
addition, pursuant to section 6 of the
Act, the State of California will be
eligible for Federal funds to implement
management actions that promote the
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protection or recovery of the San
Francisco Bay-Delta DPS of the longfin
smelt. Information on our grant
programs that are available to aid
species recovery can be found at:
https://www.fws.gov/service/financialassistance.
Please let us know if you are
interested in participating in recovery
efforts for the San Francisco Bay-Delta
DPS of the longfin smelt. Additionally,
we invite you to submit any new
information on this species whenever it
becomes available and any information
you may have for recovery planning
purposes (see FOR FURTHER INFORMATION
CONTACT).
Section 7 of the Act is titled
Interagency Cooperation and mandates
all Federal action agencies to use their
existing authorities to further the
conservation purposes of the Act and to
ensure that their actions are not likely
to jeopardize the continued existence of
listed species or adversely modify
critical habitat. Regulations
implementing section 7 are codified at
50 CFR part 402.
Section 7(a)(2) states that each Federal
action agency shall, in consultation with
the Secretary, ensure that any action
they authorize, fund, or carry out is not
likely to jeopardize the continued
existence of a listed species or result in
the destruction or adverse modification
of designated critical habitat. Each
Federal agency shall review its action at
the earliest possible time to determine
whether it may affect listed species or
critical habitat. If a determination is
made that the action may affect listed
species or critical habitat, formal
consultation is required (50 CFR
402.14(a)), unless the Service concurs in
writing that the action is not likely to
adversely affect listed species or critical
habitat. At the end of a formal
consultation, the Service issues a
biological opinion, containing its
determination of whether the Federal
action is likely to result in jeopardy or
adverse modification.
Examples of discretionary actions for
the San Francisco Bay-Delta DPS of the
longfin smelt that may be subject to
consultation procedures under section 7
are land management or other
landscape-altering activities on Federal
lands administered by the Service,
National Park Service, Department of
Defense, Reclamation, U.S. Army Corps
of Engineers, or U.S. Department of
Agriculture, as well as actions on State,
Tribal, local, or private lands that
require a Federal permit (such as a
permit from the U.S. Army Corps of
Engineers under section 404 of the
Clean Water Act (33 U.S.C. 1251 et seq.)
or a permit from the Service under
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61047
section 10 of the Act) or that involve
some other Federal action (such as
funding from the Federal Highway
Administration, Federal Aviation
Administration, or the Federal
Emergency Management Agency).
Federal actions not affecting listed
species or critical habitat—and actions
on State, Tribal, local, or private lands
that are not federally funded,
authorized, or carried out by a Federal
agency—do not require section 7
consultation. Federal agencies should
coordinate with the local Service Field
Office (see FOR FURTHER INFORMATION
CONTACT) with any specific questions on
section 7 consultation and conference
requirements.
The Act and its implementing
regulations set forth a series of general
prohibitions and exceptions that apply
to endangered wildlife. The prohibitions
of section 9(a)(1) of the Act, and the
Service’s implementing regulations
codified at 50 CFR 17.21, make it illegal
for any person subject to the jurisdiction
of the United States to commit, to
attempt to commit, to solicit another to
commit or to cause to be committed any
of the following acts with regard to any
endangered wildlife: (1) import into, or
export from, the United States; (2) take
(which includes harass, harm, pursue,
hunt, shoot, wound, kill, trap, capture,
or collect) within the United States,
within the territorial sea of the United
States, or on the high seas; (3) possess,
sell, deliver, carry, transport, or ship, by
any means whatsoever, any such
wildlife that has been taken illegally; (4)
deliver, receive, carry, transport, or ship
in interstate or foreign commerce, by
any means whatsoever and in the course
of commercial activity; or (5) sell or
offer for sale in interstate or foreign
commerce. Certain exceptions to these
prohibitions apply to employees or
agents of the Service, the National
Marine Fisheries Service, other Federal
land management agencies, and State
conservation agencies.
We may issue permits to carry out
otherwise prohibited activities
involving endangered wildlife under
certain circumstances. Regulations
governing permits for endangered
wildlife are codified at 50 CFR 17.22,
and general Service permitting
regulations are codified at 50 CFR part
13. With regard to endangered wildlife,
a permit may be issued: for scientific
purposes, for enhancing the propagation
or survival of the species. The statute
also contains certain exemptions from
the prohibitions, which are found in
sections 9 and 10 of the Act.
It is the policy of the Services, as
published in the Federal Register on
July 1, 1994 (59 FR 34272), to identify,
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to the extent known at the time a
species is listed, specific activities that
will not be considered likely to result in
violation of section 9 of the Act. To the
extent possible, activities that will be
considered likely to result in violation
will also be identified in as specific a
manner as possible. The intent of this
policy is to increase public awareness of
the effect of a listing on proposed and
ongoing activities within the range of
the species.
As discussed above, certain activities
that are prohibited under section 9 may
be permitted under section 10 of the
Act. In addition, to the extent currently
known, the following activities will not
be considered likely to result in
violation of section 9 of the Act: (1) take
of the longfin smelt outside the range of
the DPS as identified in figure 1 above;
(2) take as a result of recreational fishing
as permitted by the State of California;
or (3) recreational boating on openwater areas of the San Francisco BayDelta Estuary.
This list is intended to be illustrative
and not exhaustive; additional activities
that will not be considered likely to
result in violation of section 9 of the Act
may be identified during coordination
with the local field office, and in some
instances (e.g., with new information),
the Service may conclude that one or
more activities identified here will be
considered likely to result in violation
of section 9.
To the extent currently known, the
following is a list of examples of
activities that will be considered likely
to result in violation of section 9 of the
Act in addition to what is already clear
from the descriptions of the prohibitions
found at 50 CFR 17.21: (1) handling or
collecting individuals of the DPS; (2)
destruction/alteration of the Bay-Delta
longfin smelt’s habitat by discharge of
fill material, dredging, draining,
ditching, or stream channelization or
diversion; (3) unauthorized diversion or
alteration of surface flow into the San
Francisco Bay-Delta estuary by removal
of freshwater from rivers, streams,
wetlands, and other aquatic features; (4)
introduction of contaminants that may
degrade water quality of the San
Francisco Bay-Delta estuary; or (5)
introduction of nonnative species that
compete with or prey upon the BayDelta longfin smelt or alter food
resources for the DPS.
This list is intended to be illustrative
and not exhaustive; additional activities
that will be considered likely to result
in violation of section 9 of the Act may
be identified during coordination with
the local field office, and in some
instances (e.g., with new or site-specific
information), the Service may conclude
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that one or more activities identified
here will not be considered likely to
result in violation of section 9.
Questions regarding whether specific
activities would constitute violation of
section 9 of the Act should be directed
to the San Francisco Bay-Delta Fish and
Wildlife Office (see FOR FURTHER
INFORMATION CONTACT).
II. Critical Habitat
Section 4(a)(3) of the Act and
implementing regulations (50 CFR
424.12) require that we designate
critical habitat at the time a species is
determined to be an endangered or
threatened species, to the maximum
extent prudent and determinable. In the
October 7, 2022, proposed listing rule
(87 FR 60957 at 60970), we determined
that designation of critical habitat was
prudent but not determinable because
specific information needed to analyze
the impacts of designation was lacking.
Since the publication of the proposed
listing rule, we have obtained the
necessary information and are in the
process of developing a proposed
critical habitat designation for the BayDelta longfin smelt. We plan to publish
a proposed critical habitat rule in the
near future and complete a final
designation as required by sections
4(a)(3) and 4(b)(6)(C)(ii) of the Act.
Required Determinations
National Environmental Policy Act (42
U.S.C. 4321 et seq.)
It is our position that, outside the
jurisdiction of the U.S. Court of Appeals
for the Tenth Circuit, we do not need to
prepare environmental analyses
pursuant to the National Environmental
Policy Act (42 U.S.C. 4321 et seq.) in
connection with regulations adopted
pursuant to section 4(a) of the Act. We
published a notice outlining our reasons
for this determination in the Federal
Register on October 25, 1983 (48 FR
49244). This position was upheld by the
U.S. Court of Appeals for the Ninth
Circuit (Douglas County v. Babbitt, 48
F.3d 1495 (9th Cir. 1995), cert. denied
516 U.S. 1042 (1996)).
Government-to-Government
Relationship With Tribes
In accordance with the President’s
memorandum of April 29, 1994
(Government-to-Government Relations
with Native American Tribal
Governments; 59 FR 22951, May 4,
1994), Executive Order 13175
(Consultation and Coordination with
Indian Tribal Governments), the
President’s memorandum of November
30, 2022 (Uniform Standards for Tribal
Consultation; 87 FR 74479, December 5,
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2022), and the Department of the
Interior’s manual at 512 DM 2, we
readily acknowledge our responsibility
to communicate meaningfully with
federally recognized Tribes and Alaska
Native Corporations on a governmentto-government basis. In accordance with
Secretaries’ Order 3206 of June 5, 1997
(American Indian Tribal Rights, FederalTribal Trust Responsibilities, and the
Endangered Species Act), we readily
acknowledge our responsibilities to
work directly with Tribes in developing
programs for healthy ecosystems, to
acknowledge that Tribal lands are not
subject to the same controls as Federal
public lands, to remain sensitive to
Indian culture, and to make information
available to Tribes. No Tribal lands were
identified within the range of the BayDelta longfin smelt, and we did not
receive any information during our
development of the SSA report for the
DPS or the two open public comment
periods. We will continue to reach out
and coordinate with Tribal entities
during the development of our recovery
planning and critical habitat designation
processes for the Bay-Delta longfin
smelt.
References Cited
A complete list of references cited in
this rulemaking is available on the
internet at https://www.regulations.gov
and upon request from the San
Francisco Bay-Delta Fish and Wildlife
Office (see FOR FURTHER INFORMATION
CONTACT).
Authors
The primary authors of this rule are
the staff members of the Fish and
Wildlife Service’s Species Assessment
Team and the San Francisco Bay-Delta
Fish and Wildlife Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species,
Exports, Imports, Plants, Reporting and
recordkeeping requirements,
Transportation, Wildlife.
Signing Authority
Martha Williams, Director of the U.S.
Fish and Wildlife Service, approved this
action on June 14, 2024, for publication.
On July 22, 2024, Martha Williams
authorized the undersigned to sign the
document electronically and submit it
to the Office of the Federal Register for
publication as an official document of
the U.S. Fish and Wildlife Service.
Regulation Promulgation
Accordingly, we amend part 17,
subchapter B of chapter I, title 50 of the
Code of Federal Regulations, as set forth
below:
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PART 17—ENDANGERED AND
THREATENED WILDLIFE AND PLANTS
in alphabetical order under FISHES to
read as follows:
2. Amend § 17.11 in paragraph (h), in
the List of Endangered and Threatened
Wildlife, by adding an entry for ‘‘Smelt,
longfin [San Francisco Bay-Delta DPS]’’
§ 17.11 Endangered and threatened
wildlife.
■
1. The authority citation for part 17
continues to read as follows:
■
Common
name
Authority: 16 U.S.C. 1361–1407; 1531–
1544; and 4201–4245, unless otherwise
noted.
Scientific
name
*
*
*
Smelt, longfin [San Francisco Bay-Delta DPS].
Where listed
*
*
*
*
U.S.A. (CA) ....................
*
*
*
*
(h) * * *
*
*
E
*
*
*
[FR Doc. 2024–16380 Filed 7–29–24; 8:45 am]
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*
*
*
*
89 FR [INSERT FIRST PAGE OF FEDERAL
REGISTER PUBLICATION], 7/30/2024.
Madonna Baucum,
Regulations and Policy Chief, Division of
Policy, Economics, Risk Management, and
Analytics of the Joint Administrative
Operations, U.S. Fish and Wildlife Service.
VerDate Sep<11>2014
*
Listing citations and
applicable rules
Status
*
FISHES
*
*
Spirinchus thaleichthys ..
*
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Agencies
[Federal Register Volume 89, Number 146 (Tuesday, July 30, 2024)]
[Rules and Regulations]
[Pages 61029-61049]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-16380]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2022-0082; FXES1111090FEDR-245-FF09E21000]
RIN 1018-BG07
Endangered and Threatened Wildlife and Plants; Endangered Species
Status for the San Francisco Bay-Delta Distinct Population Segment of
the Longfin Smelt
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
endangered species status under the Endangered Species Act of 1973, as
amended (Act), for the San Francisco Bay-Delta distinct population
segment (DPS) of longfin smelt (Spirinchus thaleichthys), a fish
species of the Pacific Coast. This rule extends the protections of the
Act to this DPS and adds it to the List of Endangered and Threatened
Wildlife.
DATES: This rule is effective August 29, 2024.
[[Page 61030]]
ADDRESSES: This final rule is available on the internet at https://www.regulations.gov. Comments and materials we received on the proposed
rule are available for public inspection at https://www.regulations.gov
at Docket No. FWS-R8-ES-2022-0082.
Availability of supporting materials: Supporting materials we used
in preparing this rule, such as the species status assessment report,
are available at https://www.regulations.gov at Docket No. FWS-R8-ES-
2022-0082.
FOR FURTHER INFORMATION CONTACT: Donald Ratcliff, Field Supervisor,
U.S. Fish and Wildlife Service, San Francisco Bay-Delta Fish and
Wildlife Office, 650 Capitol Mall, Suite 8-300, Sacramento, CA 95814;
telephone 916-930-5603. Individuals in the United States who are deaf,
deafblind, hard of hearing, or have a speech disability may dial 711
(TTY, TDD, or TeleBraille) to access telecommunications relay services.
Individuals outside the United States should use the relay services
offered within their country to make international calls to the point-
of-contact in the United States.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species (including
a distinct population segment of a species) warrants listing if it
meets the definition of an endangered species (in danger of extinction
throughout all or a significant portion of its range) or a threatened
species (likely to become endangered within the foreseeable future
throughout all or a significant portion of its range). If we determine
that a species warrants listing, we must list the entity promptly and
designate the species' critical habitat to the maximum extent prudent
and determinable. We have determined that the San Francisco Bay-Delta
distinct population segment (DPS) of longfin smelt (hereafter Bay-Delta
longfin smelt) meets the definition of an endangered species;
therefore, we are listing it as such. Listing a species as an
endangered species can be completed only by issuing a rule through the
Administrative Procedure Act rulemaking process (5 U.S.C. 551 et seq.).
What this document does. This rule lists the Bay-Delta longfin
smelt as an endangered species under the Endangered Species Act and
adds the Bay-Delta longfin smelt to the List of Endangered and
Threatened Wildlife in title 50 of the Code of Federal Regulations at
50 CFR 17.11(h).
The basis for our action. Under the Act, we may determine that a
species is an endangered or threatened species because of any of five
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or manmade factors affecting its
continued existence. We have determined that the Bay-Delta longfin
smelt is endangered due to the following threats: altered hydrology
(Factor A; largely attributable to water management, including water
diversions and channel modifications), nonnative species (Factors C and
E), and the effects of climate change (Factor E; by exacerbating
drought, decreasing river and stream flows, and increasing air and
water temperatures).
Section 4(a)(3) of the Act requires the Secretary of the Interior
(Secretary), to the maximum extent prudent and determinable, to
designate critical habitat concurrent with listing. We will publish a
proposed critical habitat rule in a future edition of the Federal
Register.
Previous Federal Actions
On October 7, 2022, the proposed rule to list the Bay-Delta longfin
smelt published in the Federal Register (87 FR 60957). On February 27,
2023, we published a document in the Federal Register (88 FR 12304)
that announced a public hearing and reopened the comment period for the
proposed rule. Please see the proposed listing rule for a detailed
description of previous Federal actions concerning this species.
On December 22, 2023, San Francisco Baykeeper (Baykeeper), a
nonprofit corporation, filed a complaint in the U.S. District Court for
the Northern District of California (San Francisco Baykeeper v. United
States Fish and Wildlife Service, et al. (Case 4:23-cv-06601-LB))
challenging the Service's failure to complete its statutory obligations
to make a final listing determination for the Bay-Delta longfin smelt.
On April 5, 2024, the court issued an order requiring us to submit the
final listing determination to the Office of the Federal Register by
July 22, 2024. This document satisfies our requirement for completion
of our final listing rule.
Peer Review
A species status assessment (SSA) team prepared an SSA report for
the Bay-Delta longfin smelt. The SSA team was composed of Service
biologists, in consultation with other species experts including those
from the California Department of Fish and Wildlife. The SSA report
represents a compilation of the best scientific and commercial data
available concerning the status of the Bay-Delta longfin smelt,
including the impacts of past, present, and future factors (both
negative and beneficial) affecting the species.
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), and our August 22,
2016, memorandum updating and clarifying the role of peer review of
listing actions under the Act, we solicited independent scientific
review of the information contained in the draft Bay-Delta longfin
smelt SSA report (Service 2021, entire). As discussed in the proposed
rule, we sent the 2021 SSA report to five independent peer reviewers
and received three responses. The peer reviews can be found at https://www.regulations.gov at Docket No. FWS-R8-ES-2022-0082 under supporting
documents. In preparing the proposed rule, we incorporated the results
of these reviews, as appropriate, into a revised draft SSA report
(Service 2022, entire) and made this 2022 version available to the
public on https://www.regulations.gov at Docket No. FWS-R8-ES-2022-0082
during the open comment periods. We have since incorporated any
additional edits as appropriate based on public comments received
during the public comment periods into the current SSA report, which is
the foundation for this final rule (Service 2024, entire). A summary of
the peer review comments and our responses can be found in the Summary
of Comments and Recommendations, below.
Summary of Changes From the Proposed Rule
Since the October 7, 2022, proposed rule and February 27, 2023,
document reopening the comment period and announcing a public hearing
were published, we received comments from the public on the proposed
listing rule and 2022 SSA report. After the second comment period
closed on March 29, 2023, we also received additional comments on
August 16, October 23, and December 12, 2023, from representatives of
the Coalition for a Sustainable Delta. The Coalition also provided
comments during the open comment periods for the proposed rule to
https://www.regulations.gov at Docket No. FWS-R8-ES-2022-0082 (see
documents FWS-R8-ES-2022-0082-0009 and -0024).
After reviewing all the information we received, we updated and
revised the 2022 SSA report to incorporate any grammatical edits,
clarifications, and
[[Page 61031]]
formatting changes. We also revised the count-based population
viability analysis (see Service 2024, appendix B) based on information
received from comments on the proposed rule and peer review of the
information associated with publication of the analysis (Tobias et al.
2023, entire) in a scientific journal. The revisions to the analysis
were associated with our methodology of estimating population growth
rates and assisted in accounting for observation error in our
estimates. Additionally, we also compared density-dependent model
formulations to confirm sufficiency of our density-independent model.
The changes made to the SSA report and appendix B did not significantly
change our determination of status of the Bay-Delta longfin smelt in
this final rule.
Additionally, in the October 7, 2022, proposed listing rule, we
determined the designation of critical habitat for the DPS to be not
determinable due to a lack of necessary information to complete our
analysis. We are currently in the review process of determining
critical habitat for the DPS, and a proposed rule will be forthcoming
(see Critical Habitat, below).
Summary of Comments and Recommendations
In the proposed rule published on October 7, 2022 (87 FR 60957),
and reopening document published on February 27, 2023 (88 FR 12304), we
requested that all interested parties submit written comments on the
proposal by December 6, 2022, and March 29, 2023, respectively. We also
contacted appropriate Federal and State agencies, scientific experts
and organizations, and other interested parties and invited them to
comment on the proposal. A newspaper notice inviting general public
comment was published in the Sacramento Bee on October 10, 2022
(McClatchy 2022, entire). On November 21, 2022, we received a written
request from the public for a public hearing (Barajas et al. 2022,
entire). We held a virtual public hearing on the proposed listing rule
on March 14, 2023, as described in our February 27, 2023, Federal
Register document (88 FR 12304 at 12305) reopening the comment period
and announcing the virtual public hearing. All substantive information
received during both comment periods or subsequently has either been
incorporated directly into this final determination as appropriate or
is addressed below.
Peer Reviewer Comments
As discussed in Peer Review above, we received comments from three
peer reviewers on the draft SSA report (Service 2021, entire). We
reviewed all comments we received from the peer reviewers for
substantive issues and new information regarding the information
contained in the 2021 SSA report. The peer review comments primarily
fell into two main categories: (1) comments that provided grammatical
or editorial corrections or minor clarifications of fact or that had no
suggestions for changes to the SSA report but were either just
expressing agreement or opposition and (2) comments that would affect
the interpretation of available data and information presented in the
SSA report. Peer review greatly assisted us to clarify our presentation
of the substantial body of scientific information on Bay-Delta longfin
smelt in the revised draft SSA report (Service 2022, entire) and the
current SSA report (Service 2024, entire). Peer reviewer comments are
addressed in the following summary. As discussed above, because we
conducted this peer review prior to the publication of our proposed
rule, we had already incorporated all applicable peer review comments
into 2022 version of the SSA report, which was the foundation for the
proposed rule. Additional comments received from the public have also
been incorporated into the current version of the SSA report as
necessary (Service 2024, entire) and together they are the foundation
of this final rule.
(1) Comment: One peer reviewer stated that use of survey indices is
not a good metric for data analysis and suggested using catch data
instead.
Our response: We acknowledge that survey indices are not absolute
census measures. However, we did compare existing Bay-Delta longfin
smelt catch data (catch-per-unit-effort (CPUE) values from Stompe et
al. 2020, entire) to the survey indices used in our analysis and got
very similar results to what is presented in appendix B of the 2022 and
2024 SSA reports (Service 2022, pp. 110-123, Service 2024, pp. 115-
128). As noted in the introduction of the technical note, CPUE and the
Interagency Ecological Program (IEP) estimates both constitute indices
of Bay-Delta longfin smelt abundance. Our use of abundance indices was
not to determine the exact number of Bay-Delta smelt individuals but to
use the multiple survey indices to determine trend information for the
Bay-Delta longfin smelt. We consider the multiple survey efforts, which
use varying sampling methods, as an appropriate measure to determine
such trend information.
(2) Comment: One peer reviewer mentioned that our analysis included
a ``temporal bias'' in the 20-mm and fall midwater trawl (FMWT) survey
data (referring to the ``wet'' period starting the data series compared
to the recent dry period). The reviewer suggested that we consider
comparing wet periods to wet periods and dry periods to dry periods to
more appropriately demonstrate the decline.
Our response: The section of the draft SSA report referred to by
the reviewer (Service 2021, pp. 124-158) was intended to be a
descriptive discussion on the statistical analysis of the abundance
indices by the various survey efforts through time. In the revised
draft SSA report (Service 2022, pp. 107-192), we revised the section to
focus more on the descriptive statistics without calculating percent
declines to avoid any possible perception of false precision within a
decades-long data series. In the population viability analysis
presented in our revised draft SSA report (Service 2022, appendix B)
and now the updated modeling effort (the analysis has since published
as Tobias et al., 2023, entire) described in appendix B of the current
SSA report (Service 2024, appendix B), we interpret the full-time
course of the suite of available data that includes any variance
between wet or dry years.
(3) Comment: One peer reviewer suggested that the geographic and
depth bias to FMWT make it ineffective as a survey for longfin smelt
due to the fact that the FMWT does not sample the entire estuary or the
entire water column.
Our response: The comment correctly points out that there are
differences in spatial coverage both geographically and within the
water column amongst the various survey efforts. However, we did not
rely entirely on the FMWT as the only information in our analysis. To
avoid any bias from any one survey effort, we used the information from
all survey efforts in our modeling and overall analysis. Because none
of the currently existing long-term monitoring surveys' sampling
designs provides estuary-wide and full water column coverage, we
consider that our methodology as identified in appendix B of the
current SSA report (Service 2024) to determine trend information and
extinction risk is a robust technical analysis as it helps reduce the
effects of inflated variance through inverse weighting and is based on
the best available scientific information available.
[[Page 61032]]
(4) Comment: One peer reviewer disagreed with our description of
the importance of freshwater flow into the San Francisco Bay estuary
and cited an analysis that indicated that freshwater flow was not the
primary factor contributing to the decline of Bay-Delta longfin smelt
(Phillis 2019, entire). The peer reviewer points to information
indicating that freshwater flow into the estuary did not cause as
substantial population rebound during recent wet periods as has been
observed in prior decades and that the relationship between freshwater
flow and population abundance is weakening (Tamburello et al. 2019,
entire). The peer reviewer further points out that juvenile-to-adult
survival was not significantly affected by freshwater flow into the
estuary (Nobriga and Rosenfield 2016, entire).
Our response: We acknowledge that the relationship between
increased freshwater flow and population abundance has recently been
found to be decreasing. As a result, we have amended the SSA report to
state that freshwater flow, while a primary driver of abundances, is
not necessarily the primary driver influencing abundance of the current
population (Service 2024, pp. 28-43). However, the peer reviewer's
statement overlooks the influence of a massively declining adult
population on the abundance of offspring that can be produced when
favorable freshwater flow conditions exist. Other factors such as the
size of the current adult breeding population and food resource
limitations also play a role in the current status of the DPS, and we
made clarifications in the current SSA report to also point to these
other factors (Service 2024, pp. 35-36).
Public Comments
Influences on Water Temperature and Salinity
(5) Comment: We received several comments contending that the 2022
SSA report and proposed rule mischaracterize the relationship between
water temperatures and San Francisco Bay Delta outflow. The commenters
stated that estuary water temperatures are governed by a multitude of
complex factors related to prevailing atmospheric conditions and are
not influenced by San Francisco Bay Delta outflow.
Our response: In the 2022 SSA report and proposed rule, we
acknowledge the complexity of factors influencing water temperature in
the San Francisco Bay Delta. We agree with commenters that estuary
water temperatures are governed by a multitude of complex factors and
that atmospheric forcing is the dominant factor in determining water
temperature in the estuary. However, existing literature suggests
increased inflow can influence San Francisco Bay Delta temperatures.
Some studies have found evidence that increased San Francisco Bay Delta
inflow can lead to cooler than predicted temperatures in the San
Francisco Bay Delta over short timespans (Wagner et al. 2011, p. 551;
Wagner 2012, p. 78). The current SSA report better clarifies the
relationship between San Francisco Bay Delta inflow/outflow and water
temperatures (Service 2024, pp. 27-28).
(6) Comment: One commenter suggested that our conclusions regarding
water temperature conditions are not accurate. Specifically, the
commenter stated that temperature conditions in the San Francisco Bay-
Delta never exceed 20 degrees Celsius ([deg]C) (68 degrees Fahrenheit
([deg]F)) in the winter-spring in the low-salinity zone, suggesting
that high water temperatures are not a threat to larval and post-larval
Bay-Delta longfin smelt.
Our response: The commenter's statement that water temperatures
never exceed 20 [deg]C (68 [deg]F) in the winter and spring within the
low-salinity zone is incorrect. Water temperatures in May within the
low-salinity zone have been found to exceed this temperature
(California Department of Water Resources 2020, entire). Lab studies
sampling Bay-Delta longfin smelt collected within the San Francisco Bay
have shown that water temperatures above 20 [deg]C (68 [deg]F) cause
molecular stress responses (Jeffries et al. 2016, entire) and that
temperatures greater than 15 [deg]C (59 [deg]F) may impair the
viability of larval Bay-Delta longfin smelt (Yanagitsuru et al. 2021,
entire). Water temperatures are predicted to increase in the estuary as
a result of climate change and are likely to be an important factor in
the future condition of the DPS (Service 2024, pp. 63-71).
Food Limitation
(7) Comment: A commenter stated that the 2022 SSA report fails to
support the conclusion that food limitation may act as a stressor on
the Bay-Delta longfin smelt.
Our response: In our discussion of prey availability and the
decline of the DPS in the 2022 SSA, we presented the current scientific
understanding and our conclusions are based on the best scientific
information available (Service 2022, pp. 35-36). We acknowledge in the
current SSA report that the prey species Eurytemora affinis has not
been statistically linked to the survival of larval longfin smelt
(Service 2024, pp. 35-36). We also acknowledge in the 2024 SSA report
that although DPS abundance was observed to decline following the
overbite clam (P. amurensis) invasion, no direct statistical support
for a bottom-up longfin-mysid link has been established (Service 2024,
pp. 35-36). The two primary prey taxa of the DPS have substantially
declined compared to historical levels when overbite clam was not
present (Kimmerer and Orsi 1996, p. 412). Research into the invasion of
the nonnative overbite clam into the estuary, although not definitive,
does suggest there is a possible link between the invasion and the
subsequent decline of longfin smelt (Kimmerer 2002, p. 47; Feyrer et
al. 2003, pp. 284-286; Thomson et al. 2010, p. 1443) with more recent
research finding a significant positive correlation between available
prey biomass and feeding success of Bay-Delta longfin smelt in the
estuary, suggesting prey availability could influence growth and
survival (Barros et al. 2022, p. 1773). The inability to statistically
link declines in prey directly with declines in the DPS does not
eliminate the likelihood that prey abundances are somehow linked to
survival, but it suggests that factors affecting survival are complex
and they may be partly attributable to prey abundances.
Entrainment
(8) Comment: We received two comments regarding entrainment rates
of the DPS as a result of water diversion from the estuary. One
commenter suggested the entrainment rates cited in the 2022 SSA report
were overestimates because estimates were based on data that did not
cover the full geographic extent of DPS larvae within the San Francisco
Bay-Delta. The other commenter stated that the 2022 SSA report
underestimates entrainment in the studies cited in the 2022 SSA report
because the models excluded juvenile/adult entrainment, underestimated
the length of time larvae are vulnerable to entrainment, and failed to
account for indirect mortality.
Our response: The research discussed in the 2022 SSA report
regarding entrainment has since been published and is publicly
available (Gross et al. 2022, entire; Kimmerer and Gross 2022, entire).
The authors of these papers acknowledged longfin smelt extend beyond
the geographic extent of the sampling scheme used in these studies and
took measures to correct for this bias. The results of these studies
suggest that under current Old and Middle Rivers (OMR) flow management
strategies, entrainment of Bay-Delta longfin smelt has not been
substantial
[[Page 61033]]
enough to affect DPS population dynamics. Estimates from these two
studies currently represent the best commercial and scientific data
available and are discussed in the current SSA report (Service 2024,
pp. 41-43). A pilot study examining entrainment of larval smelts is
ongoing and aims to answer some of the current uncertainties. Over the
next few years, life cycle modeling work by the Service will better
quantify the cumulative impact of entrainment of multiple life stages
on the DPS.
Contribution of Bay Tributaries
(9) Comment: We received multiple comments expressing concerns
regarding how the 2022 SSA report and proposed rule addressed portions
of the population that inhabit areas outside of the sampling footprint
of most long-term surveys, particularly areas in and around Bay
tributaries. Some of these commenters claim the Service disregarded
this portion of the population in our determination and ignored the
contribution of San Francisco Bay-Delta tributaries and recent
restoration efforts of these areas to the DPS's current abundance,
pointing to recent research (i.e., Lewis et al. 2019a and 2019b) as
evidence of population redundancy. The commenters concluded that
because the Service did not consider the DPS's use of these areas in
evaluating abundance of the Bay-Delta longfin smelt, the DPS is not
experiencing population declines as evidenced by continued inhabitation
of all geographic units in its range, and, therefore, the DPS is not at
substantial risk of extinction or extirpation in any portion of its
documented range.
Our response: Both the 2022 and 2024 SSA reports frequently
acknowledge the inhabitation of Bay tributaries and recognize the
important role they may have in reproduction, particularly in wet years
(Service 2022, pp. 12, 19, 24; Service 2024, pp. 12, 21, 25). However,
substantial contributions of recruits from these tributaries appear to
be limited to wet years, and typically the majority of suitable
spawning and rearing habitat is still the estuary's major low-salinity
zone, which is usually located between Suisun Bay and the Delta
(Kimmerer et al. 2013, figure 2, p. 7; Lewis et al. 2019a, p. 3; Lewis
et al. 2019b, p. 6). Targeted sampling of some of these habitats in Bay
tributaries has begun only recently; therefore, no time series exist on
the time scale required to analyze population trends in these habitats.
As such, there was no practical method to include data from these
limited studies to inform our statistical analyses. However, recruits
that hatched in Bay tributaries are available to the San Francisco Bay
Study (SFBS) once they enter the larger Bays, so population
contributions from Bay tributaries should be captured by SFBS indices.
We agree with commenters that restoration of the Bay tributaries
would provide valuable benefits to the DPS. However, these benefits
would likely occur during the spawning and rearing season of wet years
rather than during the extended summer/fall occupancy of these habitats
as the commenters suggested. During the summer and fall when Bay-Delta
longfin smelt are occupying these areas, they appear to be mostly
inhabiting deeper habitat as evidenced by the higher catch in the otter
trawl surveys compared to the mid-water trawl surveys (Rosenfield and
Baxter 2007, p. 1586). As such, restoration of shallower tidal wetlands
in the lower Bay tributaries may not provide suitable habitat during
the summer and early fall, as temperatures in these shallow habitats
can approach and exceed the thermal tolerance of Bay-Delta longfin
smelt during these times.
We disagree with the statement that the Bay-Delta longfin smelt is
not experiencing population declines as evidenced by continued
inhabitation of all geographic units in its range. The complex
hydrodynamics of the estuary results in planktonic larvae and post-
larvae with limited mobility to be widely distributed throughout the
estuary, regardless of whether the habitat is suitable for any length
of time. Likewise, spawning adults appear to be primarily oriented to
cool water temperatures, which results in inhabitation of the
ephemerally cool temperatures of Bay tributaries (Lewis et al. 2019b,
p. 19). Inhabitation and spawning in these waters beyond the wettest
years likely acts as a population sink as opposed to a source, as was
observed by lack of recruitment from these habitats in most years. Lack
of successful recruitment in most years from these tributaries suggests
these habitats do not provide meaningful population redundancy.
Outflow-Abundance Relationship
(10) Comment: Some commenters took issue with our discussion on the
relationship between freshwater flow and Bay-Delta longfin smelt
abundance and questioned the validity and predictive power of the
outflow-abundance relationship pointing to recent years when observed
abundance indices were below indices predicted by the relationship.
Our response: The relationship of freshwater flow and longfin smelt
production has consistently been reaffirmed for decades based on the
published literature (Stevens and Miller 1983, pp. 431-432; Jassby et
al. 1995, p. 285; Kimmerer 2002, p. 47; Rosenfield and Baxter 2007, p.
1585; Sommer et al. 2007, p. 274; Kimmerer et al. 2009, p. 381;
MacNally et al. 2010, p. 1422; Thomson et al. 2010, pp. 1439-1440;
Maunder et al. 2015, p. 108; Nobriga and Rosenfield 2016, p. 53;
Kimmerer and Gross 2022, fig. 2, p. 2735). Nonetheless, we acknowledge
that freshwater outflow is not a perfect predictor of Bay-Delta longfin
smelt abundance due to the complexity and variable nature of habitat
within the estuary and Bay-Delta longfin smelt population dynamics. The
2022 and 2024 SSA reports acknowledge what may be step-declines (where
populations decline to a lower abundance level and do not rebound to
previous levels) or changes in the intercept of the relationship
(Service 2022, pp. 35-37; Service 2024, pp. 35-37) and acknowledge the
decreasing explanatory power of the flow-abundance model (Service 2022,
p. 37; Service 2024, p. 37). The decline of adult stock and its
resulting egg supply is the most parsimonious reason why observed
indices have been below what were predicted from data in the
increasingly distant past. The SSA reports illustrate the point that
when declining spawning stock is considered in the outflow-abundance
model, the explanatory power of the flow-abundance model did not
degrade over time (Service 2022, fig. 3.3, p. 38; Service 2024, p. 38).
Understanding the biological mechanisms behind the flow-abundance
relationship is an ongoing topic of research for the Service and the
broader scientific community in the estuary.
Low-Salinity Zone Mechanism
(11) Comment: We received a comment suggesting the expansion of the
low-salinity zone due to increased freshwater flow should not be
considered a mechanism by which freshwater flow might influence Bay-
Delta longfin smelt productivity. The commenter cited Kimmerer et al.
(2013) as evidence that the volume of low-salinity habitat in the
estuary is unrelated to the DPS's abundance.
Our response: We agree that current literature suggests higher
outflow expanding the volume of the low-salinity zone is inadequate in
explaining the population growth observed during wet years. In the 2022
SSA report, we acknowledged that expansion of the low-salinity zone may
be beneficial to larvae but did not suggest this
[[Page 61034]]
mechanism was a primary driver of the outflow-abundance relationship
(Service 2022, p. 21). Dr. Kimmerer provided an additional comment on
the proposed rule suggesting a predominant mechanism behind the
outflow-abundance relationship may be a result of favorable larval
transport and retention in the low-salinity zone and elevated prey
concentrations occurring during periods of greater freshwater flow,
resulting in higher survival and abundance. In the 2022 SSA report, we
identified and discussed this mechanism as well as other postulated
mechanisms that may contribute to the outflow-abundance relationship
(Service 2022, p. 32). In the proposed rule summarizing the information
from the 2022 SSA report, we may have underrepresented the transport
and retention mechanism. We have further described this mechanism in
the 2024 SSA report (Service 2024, pp. 21-22) and this final rule (see
Summary of Biological Status and Threats below).
(12) Comment: We received a comment regarding the habitat use of
larval/post-larval Bay-Delta longfin smelt. The commenter cited
Yanagitsuru et al. (2022), Rahman et al. (2023), and a presentation to
the Estuarine Ecological Team by Levi Lewis (2023) as new evidence that
the Bay-Delta longfin smelt larvae are distributed further downstream
and at higher salinities than previously thought.
Our response: The 2024 SSA report acknowledges the range of
salinities that larval smelt are known to utilize in the estuary
(Service 2024, p. 34). The lab studies that the commenter cites are
informative of the physiological salinity tolerances of larvae but are
not necessarily indicative of habitat use within the estuary, as such
studies ignore predation, hydrodynamics, and other relevant physical
and ecological processes. In the wild, larval abundance has been shown
to rapidly decline above 10 practical salinity unit (PSU) (Lewis et al.
2019b, p. 30), and peak recruitment and abundance occur in the range of
2 to 4 PSU (Hobbs et al. 2010, p. 564; Grimaldo et al. 2017, p. 8;
Grimaldo et al. 2020, pp. 12-14).
DPS Status
(13) Comment: We received comments stating that the San Francisco
Bay-Delta longfin smelt does not meet the criteria of a DPS according
to the Service's policy because it is not ``markedly separated'' from
the rest of the longfin smelt population and that the Bay-Delta
population is regularly mixing with other populations. The commenter
points to research conducted since our 2012 DPS determination regarding
dispersal and connectivity between the Bay-Delta population and nearby
populations farther north along the California coast.
Our response: Our DPS policy does not require absolute separation
of a DPS from other members of its species, because this can rarely be
demonstrated in nature for any population of organisms (61 FR 4724;
February 7, 1996). Our determination that the Bay-Delta longfin smelt
meets the criteria of a DPS was published in the April 2, 2012, Federal
Register (77 FR 19756). In the 2022 and 2024 SSA reports as well as our
proposed listing rule, we identified and considered more recent
research and reaffirmed that the Bay-Delta longfin smelt is a valid DPS
(87 FR 60958-60959; October 7, 2022); Service 2022, p. 10; Service
2024, p. 10). Studies that have examined longfin smelt genetics have
all found evidence that the Bay-Delta population is distinct from other
northern populations (Israel and May 2010, p. 230; Sa[gbreve]lam et al.
2021, p. 1793).
We acknowledge that Sa[gbreve]lam et al. (2021) found evidence of
northern dispersal of some individuals from the Bay-Delta population,
as evidenced by some shared genetic structure with smaller populations
in Northern California estuaries and the Columbia River. However, the
study detected no significant gene flow from any northern estuaries
southward into the Bay-Delta population, suggesting gene flow is
unidirectional in a northerly fashion. These findings suggest the Bay-
Delta population is genetically isolated, as it does not appear to be
receiving immigrants from any northern populations. Sa[gbreve]lam et
al. (2021, pp. 1793, 1802) concluded that the Bay-Delta population was
distinct and is likely an important source for maintaining nearby
populations.
A recent study published after the 2022 SSA report examined other,
much smaller, longfin smelt populations along the California coast
(Brennan et al. 2022, entire). The authors determined that estuaries in
proximity of the San Francisco Bay estuary may not be permanently
inhabited by longfin smelt, and that the Bay-Delta population may
therefore lack the resilience typically provided by metapopulations.
The authors also noted that abundance and distribution of longfin smelt
appears to have declined in other estuaries along the California coast
(Brennan et al. 2022, p. 12). This information may further support the
hypothesis that reduction of the Bay-Delta longfin smelt abundance
decreases the DPS's contribution to outside populations.
Population Viability Analysis
(14) Comment: We received comments expressing numerous concerns
regarding our population viability analysis (PVA) and its use of
population survey indices rather than actual abundance estimates for
our determination of the status for the Bay-Delta longfin smelt.
Specifically, the commenters took issue that the PVA relies on
population indices data, which they contend do not fully sample the
entire water column or habitat strata and introduce too much
uncertainty on the size of the population. The commenters state that,
because of these issues, the Service may have underestimated the size
of the population and therefore overestimated the impact of threats
facing the DPS; and the Service cannot use the PVA to determine time of
extinction or base a listing decision on such uncertain data.
Our response: As we described in the 2022 and 2024 SSA reports
(Service 2022, appendix B, pp. 111-123; Service 2024, appendix B, pp.
115-128), exact population abundance information is not necessary. A
count-based PVA can be applied to index values, where a population
index represents some portion of the total population as long as the
proportion of the population that is observed remains relatively
constant over time (Morris and Doak 2002, p. 51). General
interpretation of the abundance indices for longfin smelt or any other
species also requires this assumption or a correction for major
deviations or inconsistencies. In the SSA reports, we acknowledge the
different limitations of the long-term surveys and utilize them
collectively to reduce potential biases that may be present in any
single survey. As we state in our description of the methods used to
conduct the PVA (Service 2022, appendix B, pp. 111-123; Service 2024,
appendix B, pp. 115-128), we incorporated and applied our analysis in
the PVA using several datasets that index the abundance of Bay-Delta
longfin smelt, and these data capture the landscape of the available
information regarding the estimation of abundance for the DPS.
In our review of the status of the Bay-Delta longfin smelt, we used
all the best commercial and scientific information available to make
our determination. The PVA was just one of the many tools we used in
our analysis. We consider the PVA to be one of many appropriate tools
that provide useful information for our decision on the listing status
of the DPS. PVAs are best suited to test a range of possible conditions
or demographic assumptions to provide a range of likely fates for a
population (Morris et al.
[[Page 61035]]
1999, p. 2). We conducted sensitivity analyses to examine the effects
of different potential starting population sizes and different minimum
viable population sizes (quasi-extinction thresholds). The sensitivity
analyses showed that in most demographic scenarios tested, the
population is at a high risk of quasi-extinction in the near future
(Service 2024, figures 3 & 4, pp. 121 and 122). It is noteworthy that
the count-based PVA presented in appendix B predicts the time to quasi-
extinction under current environmental conditions and does not account
for the worsening environmental conditions associated with increases in
drought intensity or frequency, warming water temperatures, and sea-
level rise that are occurring and are predicted to continue.
(15) Comment: Some public commenters noted that the meta-analysis
was conducted on multiple surveys and as a result obscured data from
the San Francisco Bay study otter-trawl (SFBS OT) age-1 survey. The
commenters stated that the mean population growth rate for the SFBS OT
age-1 survey estimated in the PVA indicated a trend of increasing
abundance and therefore is inconsistent with the Service's finding that
the DPS is currently in danger of extinction.
Our response: In an effort to include all available data and
produce the best estimates of population growth rates, a meta-analysis
was performed using all surveys. The meta-analysis presented in
appendix B of the 2022 and 2024 SSA reports (a method proposed by a
reviewer of the 2021 SSA report) illustrates how pooling information
from the full suite of available survey data can help reduce
uncertainty in our overall estimate of the mean population growth rate.
Two important features of a meta-analysis are that the meta-mean will
be closer to the population mean on average than any of the individual
surveys (sample means) and the confidence interval will be narrower,
making it a more precise estimator of the population mean than the
estimates from the samples.
Based on review and comment of the meta-analysis (Service 2022,
appendix B, pp. 111-123), we revised our methods slightly for
estimating mean population growth rates for the DPS. As a result of
this modification, we obtained different estimates for each survey than
were reported in the 2022 SSA report (Service 2022, appendix B, p.
120). Results indicate that all of the abundance indices show long-term
population declines, and all except for the SFBS age-0 otter trawl are
statistically significant downward trends (Service 2024, appendix B,
table 2). In both the original and revised analyses, seven of the eight
surveys examined indicate a negative mean growth rate. To exclude
evidence from all seven other surveys and base our decision off the
single potentially positive survey time series would sacrifice a
substantial volume of available data and bias the results of the
analysis.
(16) Comment: Several commenters stated that the 2022 SSA report
and proposed rule indicate confirmation bias by relying on data from
the FMWT survey without acknowledging the limitations of those data or
evaluating competing data from the SFBS OT age-1 survey, which
indicates that Bay-Delta longfin smelt DPS abundance is not declining.
They further state that the FMWT survey should not be used as the
primary determinant due to its limited extent in areas surveyed and
that it may underrepresent the abundance of the DPS due to its sampling
methods.
Our response: In the 2022 and 2024 SSA reports, we do not rely on
the FMWT data any more than any other survey and acknowledge
limitations of all available surveys within the estuary (Service 2022,
pp. 107-109; Service 2024, pp. 108-110). As stated above, we utilized
information from the entire suite of surveys including the SFBS OT. As
previously discussed, the commenter's statement that the SFBS OT data
imply that the DPS is not declining is not supported by analyses of
those data (Tobias et al. 2023, entire).
In the SSA reports, we acknowledge that the FMWT does not sample
the entire range of Bay-Delta longfin smelt during the fall; however,
the survey does sample all of the low-salinity zone and some of the
mesohaline water west of the low-salinity zone when Bay-Delta longfin
smelt return to the upper estuary in the fall and early winter (Service
2022, pp. 43-46; Service 2024, pp. 43-47). Research on the Bay-Delta
longfin smelt has found that a significant proportion of age-0 (fish
younger than 1 year of age) and older individuals inhabit the low-
salinity zone prior to and during spawning, making FMWT sampling in
this region a reasonable index for population abundance (Rosenfield and
Baxter 2007, p. 1590). We also acknowledge that the FMWT does not
specifically target benthic habitat; however, except for a few
particularly deep sampling stations, fish within a geographic location
can still be sampled by the FMWT whether they are in the middle or the
bottom of the water column (Service 2022, p. 44; Service 2024, p. 44).
The ability of the FMWT to track changes in the DPS population is
evidenced by its high correlation with SFBS data (Rosenfield and Baxter
2007, p. 1590). Ultimately, both the FMWT and SFBS OT surveys use their
own standardized methods that are capable of indexing changes in
relative abundance.
(17) Comment: One commenter pointed to the increase of FMWT
abundance indices in the years of 2021-2022 as evidence of population
resilience and stated that the Service needs to evaluate this
information.
Our response: In our 2022 SSA report, we included analyses of the
2021 FMWT abundance indices (Service 2022, appendix B, p. 119) and
considered this information in our proposed rule to list the Bay-Delta
longfin smelt. Because the 2022 index was calculated after we had
concluded our analyses and published our proposed rule, we reviewed the
2022 indices in making our final determination. The Bay-Delta longfin
smelt population has historically had highly variable population growth
and declines, and such short-term population changes are not unexpected
based on the trend information over the full FMWT survey effort
(Service 2024, p. 47). Similar increases in abundance have occurred in
2000, 2006, 2011, 2013, and 2017; however, all of these increases
resulted in abundance estimates that are well below those prior to the
declines experienced in the 1980s when population numbers were several
orders of magnitude greater than those currently experienced by the
DPS.
(18) Comment: Several comments point to the wide confidence
intervals of estimated growth rates in the count-based PVA and
interpret these intervals as evidence that the Bay-Delta longfin smelt
population may be stable or increasing.
Our response: The commenters are correct in their interpretation of
the confidence intervals around the mean growth rates for individual
surveys. Bay-Delta longfin smelt population growth rates are highly
variable from year to year depending on prevailing environmental
conditions and spawning stock size. The wide confidence intervals are a
result of this variation where in some years the population grows even
though in most years it declines. To account for this variability and
differences in confidence intervals of the studies, we developed the
meta-analysis to pool estimates of the population growth rates from the
individual surveys to get a more precise estimate. Based on the overall
population trend over the length of all the studies, we determined that
the Bay-Delta longfin smelt population is in decline.
[[Page 61036]]
(19) Comment: One commenter provided a technical review of the
analyses presented in the appendices of the 2022 SSA report and stated
the information presented in appendix B required additional
documentation of the evaluation of the assumptions, reconsideration of
how the analysis accounts for sample error, and comparisons of density-
independent and density-dependent formulations of the models. In
response, the commenter provided their own meta-analysis utilizing
alternative methods to capture uncertainty.
Our response: The analysis and text of appendix B has gone through
revisions since the publication of the 2022 SSA report and some of the
points and corrections identified by the commenter have been addressed
in our current SSA report (Service 2024, appendix B). Regarding the
commenter's alternative analysis, we could not fully incorporate it
because the methods used are not sufficiently described for us to fully
evaluate them. However, taking their reported results at face value, an
increase in confidence limits would suggest a less stable population
growth rate than was reported in the SSA report. This scenario would
tend to produce a shorter time to quasi-extinction, likely offsetting
the small increase in mean that they also report. Therefore, we
conclude that this alternative analysis would also support a conclusion
that the DPS is at risk of quasi-extinction.
Contemporary Versus Pre-Development Outflow
(20) Comment: We received a comment that there has been no
statistically significant reduction in outflow throughout the winter-
spring period, nor on an annual basis when comparing contemporary to
pre-development conditions. The commenter also critiqued our use of
Reis et al. (2019) in the SSA report, stating that the study failed to
account for evapotranspiration that occurred prior to development in
the estuary.
Our response: One study comparing the pre-development conditions
and contemporary conditions of the Central Valley and potential changes
in the annual average San Francisco Bay Delta outflow found that the
outflow has not changed substantially (Fox et al. 2015, pp. 4267-4271).
However, annual average San Francisco Bay Delta outflow is not
biologically relevant to Bay-Delta longfin smelt. Contemporary water
operations have resulted in less San Francisco Bay Delta outflow during
the winter and spring months and increased outflow during the summer
months (Hutton et al. 2017a, fig. 5, p. 2507; Gross et al. 2018, fig.
4, p. 10). Winter and spring months are when Bay-Delta longfin smelt in
the estuary spawn and larvae rear in the low-salinity zone, and reduced
outflow in the winter and spring months has been repeatedly linked to
reduced juvenile Bay-Delta longfin smelt production (Stevens and Miller
1983, pp. 431-432; Jassby et al. 1995, p. 285; Kimmerer 2002, p. 47;
Rosenfield and Baxter 2007, p. 1585; Sommer et al. 2007, p. 274;
Kimmerer et al. 2009, p. 381; MacNally et al. 2010, p. 1422; Thomson et
al. 2010, pp. 1439-1440; Maunder et al. 2015, p. 108; Nobriga and
Rosenfield 2016, p. 53; Kimmerer and Gross 2022, fig. 2, p. 2735). The
reductions in February, April, and May outflows have been primarily
attributed to reductions in San Francisco Bay Delta outflow as a result
of water diversions (Hutton et al. 2017b, table 3, p. 2523).
We do not agree with the commenter's critique of Reis et al.
(2019). Differences in evapotranspiration rates are primarily a concern
when comparing pre-development and post-development outflows in the
estuary because extensive wetlands and floodplains pre-development
theoretically increased evapotranspiration (reducing San Francisco Bay
Delta outflow), but levees constructed during development largely
disconnected floodplains and resulted in decreased evapotranspiration.
By 1930, almost the entire San Francisco Bay Delta had been leveed and
reclaimed (Whipple et al. 2012, p. 25). Reis et al. (2019) examined the
years 1930-2018 when no substantial changes in estuary
evapotranspiration occurred. As a result, the authors were able to
reasonably assess the relative impact of water operations on San
Francisco Bay Delta outflows.
Underestimate of Threats
(21) Comment: One commenter stated that the Service understated the
risk to the DPS by not considering specific current proposals to
increase diversions of freshwater from the San Francisco Bay estuary
and its watershed and that if realized these projects could result in
changes to outflow in the estuary and further impact the Bay-Delta
longfin smelt. The commenter points to several proposed projects
including the Delta Conveyance Project, Sites Reservoir, and the State
Water Resources Control Board's voluntary agreement process.
Our response: In the 2022 SSA report and proposed rule, we
identified reduced freshwater flow and diversion as one of the primary
threats driving the current and future status of the Bay-Delta longfin
smelt (Service 2022, pp. 28-30; 71-73). In our analysis of future
conditions, we also acknowledged that changes in water demand may be
more severe as the information used in our analysis identified impacts
only out to the year 2030 due to the uncertainty and difficulty in
accurately identifying changes with the necessary specificity (Knowles
et al. 2018, p. 7638). However, due to the ongoing refinement of these
proposed projects a specific assessment of each project was not
possible within the timeframe for completion of our final rule. These
projects, and any attendant risk or benefits to Bay-Delta longfin
smelt, will be evaluated as they are implemented through appropriate
regulatory processes, including section 7 consultations and/or section
10 permits, and future recovery planning and implementation for the
Bay-Delta longfin smelt.
(22) Comment: One commenter stated that neither the 2022 SSA report
nor the proposed rule evaluated the threat posed by harmful algal
blooms (HABs) such as the one observed in the summer of 2022.
Our response: We agree that in our 2022 SSA report and proposed
rule, we did not include HABs as a threat to the Bay-Delta longfin
smelt or a growing stressor to fish populations in the estuary. We
agree that marine and brackish water HABs, such as the bloom that
occurred in parts of San Francisco Bay in 2022, could plausibly affect
Bay-Delta longfin smelt individuals in localized areas, but the impact
of such blooms on the DPS overall is not well studied, and the best
available information to date does not support a conclusion that HABs
are a substantial threat to the status of the DPS. However, we agree
that recent events are concerning. As emerging threats are defined and
better understood, they will inform future consultations, permits, and
recovery planning.
I. Final Listing Determination
Background
The longfin smelt is a small fish species 9-11 centimeters (cm)
(3.5-4.3 inches (in)) in length with a relatively short lifespan of
approximately 2 to 3 years. The Bay-Delta longfin smelt DPS occupies
the San Francisco Bay estuary and areas of the Pacific Ocean out to the
Farallon Islands (see figure 1). A thorough review of the taxonomy,
life history, and ecology of the Bay-Delta longfin smelt is presented
in the current SSA report (Service 2024, pp. 6-23).
[[Page 61037]]
[GRAPHIC] [TIFF OMITTED] TR30JY24.000
Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species. On April 5, 2024, jointly with the National Marine
Fisheries Service, the Service issued a final rule that revised the
regulations in 50 CFR part 424 regarding how we add, remove, and
reclassify endangered and threatened species and what criteria we apply
when designating listed species' critical habitat (89 FR 24300). On the
same day, the Service published a final rule revising our protections
for endangered species and threatened species at 50 CFR part 17 (89 FR
23919). These final rules are now in effect and are incorporated into
the current regulations. Our analysis for this final decision applied
our current regulations. Given that we proposed listing this species
under our prior regulations (revised in 2019), we have also undertaken
an analysis of whether our decision would be different if we had
continued to apply the 2019 regulations; we concluded that the decision
would be the same. The analyses under both the regulations currently in
effect and the 2019 regulations are available on https://www.regulations.gov.
The Act defines an ``endangered species'' as a species that is in
danger of extinction throughout all or a significant portion of its
range, and a ``threatened species'' as a species that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether any species is an endangered species or a threatened
species because of any 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.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself.
[[Page 61038]]
However, the mere identification of any threat(s) does not
necessarily mean that the species meets the statutory definition of an
``endangered species'' or a ``threatened species.'' In determining
whether a species meets either definition, we must evaluate all
identified threats by considering the species' expected response and
the effects of the threats--in light of those actions and conditions
that will ameliorate the threats--on an individual, population, and
species level. We evaluate each threat and its expected effects on the
species, then analyze the cumulative effect of all of the threats on
the species as a whole. We also consider the cumulative effect of the
threats in light of those actions and conditions that will have
positive effects on the species, such as any existing regulatory
mechanisms or conservation efforts. The Secretary determines whether
the species meets the definition of an ``endangered species'' or a
``threatened species'' only after conducting this cumulative analysis
and describing the expected effect on the species.
The Act does not define the term ``foreseeable future,'' which
appears in the statutory definition of ``threatened species.'' Our
implementing regulations at 50 CFR 424.11(d) set forth a framework for
evaluating the foreseeable future on a case-by-case basis, which is
further described in the 2009 Memorandum Opinion on the foreseeable
future from the Department of the Interior, Office of the Solicitor (M-
37021, January 16, 2009; ``M-Opinion,'' available online at https://www.fws.gov/library/collections/national-listing-and-classification-guidance). The foreseeable future extends as far into the future as the
U.S. Fish and Wildlife Service and National Marine Fisheries Service
(hereafter, the Services) can make reasonably reliable predictions
about the threats to the species and the species' responses to those
threats. We need not identify the foreseeable future in terms of a
specific period of time. We 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. In other words, the foreseeable future is the period of
time over which we can make reasonably reliable predictions.
``Reliable'' does not mean ``certain''; it means sufficient to provide
a reasonable degree of confidence in the prediction, in light of the
conservation purposes of the Act.
Analytical Framework
The current SSA report documents the results of our comprehensive
biological review of the best scientific and commercial data available
regarding the status of the Bay-Delta longfin smelt, including an
assessment of the potential threats to the DPS. The SSA report does not
represent our decision on whether the DPS should be listed as an
endangered or threatened species under the Act. However, it does
provide the scientific basis that informs our regulatory decisions,
which involve the further application of standards within the Act and
its implementing regulations and policies.
To assess the Bay-Delta longfin smelt's viability, we used the
three conservation biology principles of resiliency, redundancy, and
representation (Shaffer and Stein 2000, pp. 306-310). Briefly,
resiliency is the ability of the species to withstand environmental and
demographic stochasticity (for example, wet or dry, warm or cold
years); redundancy is the ability of the species to withstand
catastrophic events (for example, droughts, large pollution events),
and representation is the ability of the species to adapt to both near-
term and long-term changes in its physical and biological environment
(for example, climate conditions, pathogens). In general, species
viability will increase with increases in resiliency, redundancy, and
representation (Smith et al. 2018, p. 306). Using these principles, we
identified the DPS's ecological requirements for survival and
reproduction at the individual, population, and DPS levels, and
described the beneficial and risk factors influencing the DPS's
viability.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated the individual DPS's life-history
needs. The next stage involved an assessment of the historical and
current condition of the DPS's demographics and habitat
characteristics, including an explanation of how the DPS arrived at its
current condition. The final stage of the SSA involved making
predictions about the DPS's responses to positive and negative
environmental and anthropogenic influences. Throughout all of these
stages, we used the best available information to characterize
viability as the ability of the DPS to sustain populations in the wild
over time. We use this information to inform our regulatory decision.
The following is a summary of the key results and conclusions from
the current Bay-Delta longfin smelt SSA report (Service 2024, entire);
the full SSA report can be found at Docket No. FWS-R8-ES-2022-0082 on
https://www.regulations.gov.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of the DPS
and its resources, and the threats that influence the DPS's current and
future condition, in order to assess the DPS's overall viability and
the risks to that viability.
The needs of the Bay-Delta longfin smelt can be categorized into
three main resource and biological condition categories, and include:
(1) appropriate habitat salinity, by life stage; (2) appropriate
habitat temperature conditions, by life stage; and (3) adequate food
resources and availability, by life stage. As the Bay-Delta longfin
smelt utilizes both freshwater and saline water conditions across its
life cycle, its habitat is extremely variable. These variable
conditions, along with other factors including the interaction among
these dynamic variables, exert a strong influence on habitat
suitability across space and time.
Bay-Delta longfin smelt have temperature tolerances that impact the
volume and seasonality of suitable habitat. It is logical to presume
that the Bay-Delta DPS, inhabiting as it does the most southern portion
of the species' range, has historically been (and is) at the uppermost
temperature tolerance range of the species. Larvae appear to be adapted
to cool water conditions. Larvae inhabit water temperatures between 8
and 12 [deg]C (46 and 54 [deg]F) (Grimaldo et al. 2017, p. 8).
Available research indicates that temperatures approaching and
exceeding 15 [deg]C (59 [deg]F) impair larval viability, and hence this
benchmark may be ecologically significant. At later larval stages,
longfin smelt are still likely restricted to water temperatures below
20 [deg]C (68 [deg]F) (Jeffries et al. 2016, p. 1709). In general, age-
1 and age-0 fish inhabit 16-18 [deg]C (61-64 [deg]F) water in summer
and fall. Adults are thought to be limited by water temperature >22
[deg]C (>72 [deg]F) during the summer and likely spend the majority of
this time in cooler Bay habitats and the open ocean (see Service 2024,
p. 25). Fish return to spawn where water quality conditions are
favorable for egg survival. These conditions vary in location depending
on Delta outflow, as well as flows from Bay Area tributaries. Spawning
occurs at or below water temperatures of 13 [deg]C (55 [deg]F), but has
been documented at up to 16 [deg]C (61 [deg]F) (see Service 2024, p.
25).
Bay-Delta longfin smelt have a defined salinity tolerance range
that
[[Page 61039]]
increases as fish mature. This is consistent with their anadromous life
history requiring spawning and early rearing in fresher San Francisco
Bay Delta and Bay tributary waters. Yolk-sac larvae survive the longest
and grow the largest at 5 and 10 parts per thousand (ppth) and are able
to maintain water balance equally between 0.4 and 10 ppth, but the same
lifestage is unable to survive at 32 ppth (ocean salinity). Yolk-sac
larvae cannot complete yolk resorption in freshwater. In field surveys,
peak yolk-sac larval densities have been found at 2-4 ppth (Grimaldo et
al. 2017, p. 8), which is also concordant with the early life
salinities that produce highest survival to later life stages (Hobbs et
al. 2010, p. 564). The California Department of Fish and Wildlife's
(CDFW) 20-mm surveys have also shown peak larval distribution near this
same salinity zone (i.e., 2-4 ppth), although larvae have been detected
in salinities as high as 12 ppth (see Service 2024, pp. 25-26). The 20-
mm survey gets its name from the size at which Bay-Delta longfin smelt
are retained and readily identifiable at the fish facilities associated
with the State and Federal pumping facilities.
Available data clearly indicate a very strong association of Bay-
Delta longfin smelt to turbid water conditions. Aquatic turbidity
provides simultaneous feeding and predator avoidance advantages for
larval fishes (Utne-Palm 2002, p. 115; Pangle et al. 2012, pp. 10-11).
Turbidity enhances prey avoidance at detection distances typical of
predatory fish species. Further, the sediment and algal particles often
backlight relatively translucent zooplankton, helping larval fishes see
these prey more easily (Utne-Palm 2002, p. 119). In contrast, larger
fishes that may prey on fish larvae have longer search and reactive
distances so more sediment and algal particles are in between these
larger fish and their potential prey (Utne-Palm 2002, pp. 122-123). We
assume that these turbidity mechanisms that apply broadly to larval
fishes also apply to later life stages of Bay-Delta longfin smelt.
Taken together, recent laboratory experiments, combined with field
results, provide an assessment of early-life habitat needs favoring
more turbid conditions (Utne-Palm 2002, entire; Pangle et al. 2012,
entire).
Bay-Delta longfin smelt exhibit high prey-specificity. During the
time that longfin smelt larvae and small juveniles are feeding in low-
salinity habitats, they appear to focus on only two prey taxa. Smaller
larvae appear to primarily use the copepod Eurytemora affinis as prey,
while larger larvae and small juveniles appear to require mysids as
prey. Longfin smelt pre-spawning adults in Suisun Marsh have shown a
strong dietary preference for mysids, while relying on copepods and
amphipods when mysids are scarce (see Service 2024, pp. 26-27). As
longfin smelt exhibit very little variation in prey use, they are
considered more susceptible to food web changes than some other fishes
(Feyrer et al. 2003, p. 281). The current SSA report (Service 2024, p.
27) discusses some observations from various studies regarding affects
to the low-salinity zone from invasion by the overbite clam
(Potamocorbula amurensis) in the 1980s and potential impacts to the
Bay-Delta longfin smelt as a food limitation stressor (see below, and
also Service 2024, pp. 35-37).
Threats Influencing the Bay-Delta Longfin Smelt
The threats facing the Bay-Delta DPS of the longfin smelt include
habitat alteration (Factor A) and changes to hydrology associated with
reduced and altered freshwater flows (Factor A); increased water
temperatures (Factor A); reduced food resource availability (Factor E);
predation (Factor C); entrainment from freshwater diversion facilities
(Factor E); and contaminants (Factor E). We consider reduced and
altered freshwater flows resulting from human activities and impacts
associated with current climate change conditions (increased magnitude
and duration of drought and associated increased temperatures) as the
main threat facing the Bay-Delta longfin smelt due to the importance of
freshwater flows to maintaining the life-history functions and species
needs of the DPS. However, because the Bay-Delta longfin smelt is an
aquatic species and the needs of the species are closely tied to
freshwater input into the estuary, the impact of many of the other
threats identified above are influenced by the amount of freshwater
inflow into the system (i.e., reduced freshwater inflows reduce food
availability, increase water temperatures, and increase entrainment
potential).
Reduced and Altered Freshwater Flows
The development of dams and water delivery infrastructure built
throughout the Sacramento and San Joaquin River basins for flood
protection and water supply for agriculture and human consumption has
greatly impacted freshwater flows into the San Francisco Bay estuary
(Service 2024, section 3.1.1). The creation of this water storage and
delivery system, where water is stored during the wet season and
conveyed to farms and cities during the dry season, has resulted in one
of the largest human-altered water systems in the world (Nichols et al.
1986, p. 569). Operation of this system has resulted in a broader,
flatter hydrograph with less seasonal variability, thus changing the
timing, magnitude, and duration of freshwater flows into the San
Francisco Bay-Delta (Kimmerer 2004, p. 15; Andrews et al. 2017, p. 72;
Gross et al. 2018, p. 8). It is estimated that the Federal and State
water projects annually reduce an average of about 5 million acre-feet
(MAF) of freshwater into the San Francisco Bay Delta, while other
municipal or private reservoirs or diverters annually divert an
additional 8 MAF of potential freshwater into the San Francisco Bay
Delta (Hutton et al. 2017b, fig. 4, p. 2523). The cumulative effect of
this annual average of about 13 MAF of freshwater supplies has resulted
in a long-term decline in freshwater inflow into the estuary during the
period of February through June relative to estimates of what flows
would have been available absent water development (Gross et al. 2018,
fig. 6, p. 12; Reis et al. 2019, fig. 3, p. 12). This situation has
further increased the frequency of very low outflow years that, prior
to water development, would have been very rare and associated only
with extreme drought (Reis et al. 2019, fig. 3, p. 12).
From 1956 to the 1990s, water exports (water removed from the San
Francisco Bay Delta as a result of State (State Water Project) and
Federal (CVP) water projects) increased, rising from approximately 5
percent of the Delta freshwater inflow to approximately 30 percent of
the Delta inflow (Cloern and Jassby 2012, p. 7). By 2012, an estimated
39 percent of the estuary's unimpaired freshwater flow in total was
either consumed upstream or diverted from the estuary (Cloern and
Jassby 2012, p. 8). Water exports continue to the present day and are
expected to continue in the future.
A reduction in freshwater flows into the estuary influences and
impacts the location and function of the low-salinity zone (spawning
and rearing habitat for longfin smelt). Freshwater inflow into the
estuary and other co-linear indicators of wet versus dry conditions
during the winter and spring have been statistically associated with
recruitment of larvae to the juvenile life stage of Bay-Delta longfin
smelt (Service 2024, section 3.1.1). Prior to large-scale water exports
and reduced freshwater flows, the location of the low-salinity zone (as
represented by the 2 percent bottom salinity position, known as X2)
reached the <=55-km (<=34-mi) point in the estuary (monthly averages
from February
[[Page 61040]]
through May) in about half of all years. More recently the position of
X2 reaching at least the 55-km (34-mi) point occurred only very rarely
as a result of wet year conditions (Gross et al. 2018, fig. 6, p. 12
and fig. 7, p. 13) (Service 2024, section 3.1.1). In the case of Bay-
Delta longfin smelt, optimal growth and rearing conditions (food and
water conditions (salinity, turbidity, circulation patterns)),
especially for early life stage fish, is directly linked to freshwater
inflow to the estuary.
Drought Conditions
California's precipitation patterns can be extremely variable, and
several years of dry conditions have occurred over numerous extended
periods resulting in varying levels of drought (California Department
of Water Resources (DWR) 2020, entire). Drought periods can be
characterized as having less freshwater flow, as well as shorter
duration and lower magnitude of peak flows. The current trend in
drought conditions has recently increased in frequency, duration, and
magnitude (Swain et al. 2018, pp. 427-433). Prior to the 21st century,
dry and critically dry years occurred approximately 33 percent of the
time. However, since the year 2000, the dry and critically dry year
frequency has increased to 43 percent. Based on soil moisture
reconstruction, the period between 2000 and 2021 was probably the
driest 22-year period on record (Williams et al. 2022, p. 1). As the
existing impacts from climate change (i.e., warmer temperatures)
increase evapotranspiration in the watershed, the aforementioned water
supply needs can exacerbate the magnitude of realized dry conditions
over and above these natural patterns in precipitation and reduced San
Francisco Bay Delta freshwater inflow.
Bay-Delta longfin smelt exhibit poor survival and reproduction
during droughts (Thomson et al. 2010, pp. 1438-1446; Mahardja et al.
2021, pp. 9-10). The survival of Bay-Delta longfin smelt through their
early life stages is lower during dry conditions and higher during wet
conditions, as evidenced by Bay-Delta longfin smelt abundance indices
nearly always declining sharply during dry periods then rebounding when
wet weather returns (Mahardja et al. 2021, pp. 9-10). However, such
recovery does not always occur after each drought cycle, leading to
lower baseline numbers for the DPS (Moyle 2002, p. 237; Sommer et al.
2007, pp. 270-276). In addition, extended dry years compound the
negative impacts to Bay-Delta longfin smelt as the DPS has not shown an
ability to quickly recover and reoccupy upstream spawning habitats
following drought. These drought conditions have exacerbated the impact
of reduced freshwater flows from human activities and have been
attributed to accelerating the establishment of the overbite clam
(Potamocorbula amurensis) (see Reduced Food Resources and Pelagic
Organism Decline (POD), below) by making saline water conditions more
available throughout areas typically associated with more freshwater
(Carlton et al. 1990, pp. 90-91).
Habitat Alteration
Large-scale habitat alteration such as channelization and dredging
of streams and bays, building of levees and canals, and draining of
wetlands has occurred since the 1850s. The impacts of such in-water and
adjacent upland habitat alterations greatly affected and continues to
impact the bathymetry of the estuary by collectively making the estuary
deeper and less hydrodynamically connected to the surrounding landscape
(Andrews et al. 2017, fig. 5, p. 64). The altered waterways create more
space and avenues for the incoming tides to bring more saline water
landward. Specifically, landscape changes since 1850 are estimated to
have resulted in an average landward shift of X2 of over 3 km (2 mi)
(Andrews et al. 2017, p. 68). This change along with reductions in
freshwater input into the estuary (see Reduced and Altered Freshwater
Flows, above) has caused a winter-spring upstream (landward) shift of
X2 on the order of 10-20 km (6-12 mi). Taken together, the landscape
changes discussed above and changes to the estuary's flow regime have
changed how mixing processes function, and thus altered the habitat and
food resource opportunities available for the estuary's biota,
including the Bay-Delta longfin smelt.
Water Temperature Alterations
As described in the Life History and Biology section of the current
SSA report (Service 2024, section 2.4), Bay-Delta longfin smelt
spawning occurs within cool-water conditions below 16 [deg]C (61
[deg]F), while larvae and young juveniles show a preference for
temperatures below 15 [deg]C (59 [deg]F) and 20 [deg]C (68 [deg]F),
respectively. The embryonic through early juvenile life stages are when
Bay-Delta longfin smelt are believed to be most vulnerable to warming
temperatures because these early life stages do not possess the ability
to migrate to the cooler waters of central San Francisco Bay and the
coastal ocean due to limited motility and increases in potential
predation. Subadults and adults are thought to be limited to water
temperature below 22 [deg]C (72 [deg]F). Studies and datasets indicate
water temperatures in the San Francisco Bay Delta commonly exceed 22
[deg]C (72 [deg]F) during the summer (Vroom et al. 2017, p. 9904; data
from California Data Exchange Center, Central & Northern California
Ocean Observing System, and U.S. Geological Survey (Blodgett et al.
2011, entire). Age-1 to age-3 individuals should possess the capacity
to move to cooler waters during such times, making them less vulnerable
than larvae and age-0 juveniles. However, climate change is predicted
to substantially increase the number of days that water temperatures
are inhospitable to all life stages, likely decreasing the duration of
suitable spawning and larval rearing windows (Service 2024, section
4.2.2).
Reduced Food Resources
As discussed above and in the current SSA report (Service 2024,
section 3.1.2), the Bay-Delta longfin smelt historically limited their
diet to a relatively small number of crustacean meso- and
macrozooplankton taxa. Bay-Delta longfin smelt larvae have diets
dominated by a copepod, Eurytemora affinis, that is common in the low-
salinity zone during the spring (CDFW, unpublished data). The two most
common prey taxa for larger longfin smelt are epibenthic mysids and
amphipods (Burdi 2022, pers. comm.; CDFW unpub. Diet Study Data). The
copepod E. affinis was also at one time an important prey item for a
now much-depleted mysid species, Neomysis mercedis (Knutson and Orsi
1983, p. 478), a prey species of juvenile and adult Bay-Delta longfin
smelt.
Since the 1970s, the Eurytemora affinis population in the estuary
has been in decline, but beginning in the late 1980s, the zooplankton
community for the San Francisco Bay estuary started undergoing about a
decade of rapid change in species composition, trophic structure, and
utility for fish production (Winder and Jassby 2011, pp. 683-685;
Kratina et al. 2014, p. 1070; Brown et al. 2016, p. 8). This decline
coincided with the rapid invasion of the estuary by the nonnative
overbite clam (Carlton et al. 1990, pp. 81 and 85, fig. 3) and with an
extended drought in the Central Valley in the period 1987-1994
(Rosenfield and Baxter 2007, p. 1589).
The overbite clam is a filter feeder that is thought to have
diverted food resources from the primary food sources of, or fed
directly on, the nauplii (first larval stage) of common calanoid
copepods and resulted in their decline. These native copepods are one
of the
[[Page 61041]]
main sources of prey of larval Bay-Delta longfin smelt (Carlton et al.
1990, pp. 90-91; Kimmerer et al. 1994, p. 87; Feyrer et al. 2003, pp.
284-286; Rosenfield and Baxter 2007, p. 1589). Mysids have experienced
an over tenfold decrease in abundance and accounted for less than 4
percent of total zooplankton biomass within the estuary after 1994
(Winder and Jassby 2011, p. 684). In addition to lower abundance, the
average individual sizes of mysids in the estuary have decreased over
time, with a species composition shift towards Hyperacanthomysis
longirostris, an invasive species that reaches maturity at a smaller
mass than Neomysis species (Hennessy 2011, entire). Although Bay-Delta
longfin smelt consume these nonnative species, they are not preferred
and the change in food resources most likely results in an increased
effort for the DPS to meet its food resource needs.
To further exacerbate the impacts of the change in food resources,
the decline of the Bay-Delta longfin smelt's historical prey base has
not been accompanied by a large change in prey use by the DPS (Barros
et al. 2019, p. 15; Feyrer et al. 2003, p. 285). This finding suggests
that Bay-Delta longfin smelt had formed strong predator-prey
interactions with their primary prey, a hypothesis supported by
empirical data (MacNally et al. 2010, p. 1426). Because the DPS
exhibits very little variation in prey use despite the reduction in
natural prey availability, they are considered more susceptible to food
web changes than some other fishes (Feyrer et al. 2003, p. 281). The
decline in food resources is likely affecting juvenile and adult
longfin smelt growth and fitness as well as increasing the effort
needed to meet food resource demands (Kimmerer and Orsi 1996, pp. 418-
419; Feyrer et al. 2003, p. 281).
Predation
In the proposed rule and 2024 SSA report, we discussed the role
predation may play on individuals and various life stages of the Bay-
Delta longfin smelt (see the 2024 SSA report and proposed rule for
additional information). Because little information is available on the
exact predators of the Bay-Delta longfin smelt or the impact predation
has on the status of the DPS, we do not consider the impacts from
predation to be a primary driver, but we still include this
consideration as part of the cumulative impact from all threats for the
DPS, especially during poor habitat conditions when food is lacking.
Entrainment
Freshwater diversion occurs throughout the estuary through intake
structures for agricultural, municipal, and environmental purposes and
in some cases may lead to entrainment of Bay-Delta longfin smelt.
Entrainment occurs when the suction caused by pumping water creates an
opportunity for fish to follow or be captured by the flow of water and
become trapped and transported by the hydrodynamic footprint of those
diversions. This entrainment may result in fish, especially early-life-
stage fish, being killed or removed from the estuary. Bay-Delta longfin
smelt can be entrained in water exported by the major pumping
facilities in the South Delta (see Water Project Exports, below) when
adults and commingling age-1 individuals move upstream into the
freshwater portions of the San Francisco Bay Delta (CDFW 2020a, fig.
13, p. 53). Bay-Delta longfin smelt larvae and small juveniles that are
either rearing or being tidally dispersed landward of X2 can also be
entrained (CDFW 2020a, fig. 13, p. 53). During periods of high
freshwater flow into the estuary, Bay-Delta longfin smelt (adults,
juveniles, and larvae) are much less likely to be entrained by the
major pumping facilities in the South Delta because the low-salinity
zone is further downstream (or seaward) of the San Francisco Bay Delta.
However, changes to the estuary's landscape (see Habitat Alteration,
above) have caused the tidal flows to reach further into the Old and
Middle Rivers (Andrews et al. 2017, p. 66), which, as discussed below,
may further impact Bay-Delta longfin smelt (see Water Project Exports,
below). Below we describe the types of freshwater diversions and
exports and their impacts on Bay-Delta longfin smelt.
Water Project Exports: The State of California through the DWR and
the U.S. Bureau of Reclamation (Reclamation) operate freshwater
diversion facilities and infrastructure associated with the SWP and
CVP, respectively, which export fresh water from the Delta. The
operation of these facilities can exert a strong influence on regional
hydrodynamics (Kimmerer and Nobriga 2008, fig. 7, p. 12; Hutton et al.
2019, fig. 7, p. 11). That hydrodynamic influence can result in the
entrainment of fish, sometimes from considerable distances (Kimmerer
2008, p. 2, fig. 1, p. 3). Several methods have been implemented to
limit and offset the entrainment impacts at the SWP and CVP facilities,
including construction of forebays (areas used to collect fish before
they enter the pumps), fish screens, gate systems (used to divert fish
away from pumps), and salvage operations (active collection and
transport of fish back into the estuary). In most years, Bay-Delta
longfin smelt have been collected (``salvaged'') in the fish facilities
that are in front of each pumping plant. The salvage of fish is an
indicator that individuals are being entrained by pumping of water at
these facilities and either being killed or removed from the estuary.
The peak of salvage of age-1 and older Bay-Delta longfin smelt
typically occurred in January (Grimaldo et al. 2009, fig. 5, p. 1262).
These adult and age-1 fish likely represented individuals searching for
spawning habitats and immature individuals commingling with the adults.
The peak of salvage of age-0 fish typically occurred in April or May as
larval fish reach sizes at which they could be retained on the fish
screens of the CVP and SWP fish collection facilities. However, it is
likely some larvae began to be entrained once they started hatching in
December or January, but remained undetected until about March, with
salvage efficiency increasing in April-May as the fish grow larger.
It is possible that past entrainment and loss of Bay-Delta longfin
smelt may have reached levels of concern (CDFW 2020a, fig. 10, p. 47).
However, since 2009, the entrainment of longfin smelt has not been
substantial (Service 2024, fig. 3.4), perhaps partly due to monitoring
and management of flows in the Old and Middle Rivers (OMR) between the
Sacramento/San Joaquin River confluence and the export facilities. When
net OMR flow is positive, San Joaquin River water is generally moving
seaward through the San Francisco Bay Delta and away from the pumping
facilities. The more net negative OMR is flowing, the more the water in
the San Francisco Bay Delta is moving back upstream toward the pumping
plants and the faster that water is moving south, thereby increasing
entrainment potential. The additional negative flow causes Sacramento
River water entering the northwest portion of the San Francisco Bay
Delta to be diverted southward toward the pumping facilities rather
than seaward, which allows saltier tidal flows to move further toward
the San Francisco Bay Delta.
In order to address and minimize effects to federally listed fish
species (delta smelt (Hypomesus transpacificus), chinook salmon
(Sacramento River winter-run and Central Valley spring-run salmon
(Oncorhynchus tshawytscha), Central Valley steelhead (Oncorhynchus
mykiss), and green sturgeon (Acipenser
[[Page 61042]]
medirostris)), restrictions to pumping and other water operations
management strategies have been implemented by the DWR and Reclamation
to limit negative OMR flows and associated entrainment through the
section 7 process of the Act (Service 2008, entire; National Oceanic
and Atmospheric Administration, National Marine Fisheries Service
[NMFS] 2009, entire; Service 2019, entire; NMFS 2019, entire). In
addition, the DWR has implemented similar measures for State-listed
species (including longfin smelt) (CDFW 2009b Incidental Take Permit
(ITP), entire; CDFW 2020b, ITP, entire).
The results of two different analytical approaches using smelt
larval survey (SLS) data suggest that entrainment of fish has not
exceeded 3 percent since 2009 (Kimmerer and Gross 2022). Gross et al.
(2022) coupled particle tracking modeling with the SLS data set and
found an upper 95 percent credible interval of proportional entrainment
was 2.9 percent in the critically dry winter of 2013 and nearly zero in
the wet winter of 2017. Kimmerer and Gross (2022) analyzed all of the
SLS data in the period 2009-2020. Similarly, this approach also found
proportional entrainment was unlikely to have exceeded 3 percent (range
= 0.5 to 2.9 percent) (Kimmerer and Gross 2022, table 1). We interpret
these findings, as well as previously published information (CDFW
2020a, entire), to indicate that the OMR management strategies in place
since 2009 have been an effective conservation strategy for limiting
the impact of entrainment and its consequences for the Bay-Delta
longfin smelt. As a result, the best information currently available
indicates that management actions for operating water diversion
facilities are assisting in limiting entrainment impacts for the Bay-
Delta longfin smelt.
Contaminants
The San Francisco Bay estuary has been identified as an impaired
water body due to it containing numerous and persistent contaminant
compounds (California State Water Resources Control Board 2018,
appendix A). The list of contaminant compounds identified within the
estuary includes elemental contaminants or `metals' (e.g., mercury and
selenium), toxic organic compounds (dioxins, furans, polychlorinated
biphenyls), and pesticides (chlordane dieldrin, DDT). Additional
emerging contaminants of concern include newer pesticides, flame
retardants, nutrients, naturally occurring toxins, microplastics, and
pharmaceuticals and personal care products (i.e., plastic microbeads,
insect repellant, sunscreen, cosmetics, etc.) (Klosterhaus et al. 2013,
pp. 97-98, table 1; Sutton et al. 2017, entire). Ongoing analysis of
water in the San Francisco Bay Delta suggests that on average 10 new
synthetic organic pesticide chemicals are detected every year
(California Department of Pesticide Regulation 2020, dataset). Water
sampling in one study of the San Francisco Bay Delta indicated the
presence of more than 50 chemical compounds from a single 1-liter (L)
(34-ounce (oz)) water sample (Moschet et al. 2017, pp. 1557-1560).
The sources of contaminants include discharge from municipal
wastewater treatment plants, agricultural outfalls, stormwater runoff,
anti-fouling paints on boat and ship hulls, and direct human
application of pest and aquatic plant control compounds (Service 2024,
section 3.1.6). Legacy contaminants in the Bay-Delta (those from
historical loading, such as organochlorine chemicals (e.g., DDT) from
past agricultural use and mercury from past mining activity) have been
shown to persist in the environment and continue to impact ecosystems
and can bioconcentrate through the food web, posing additional health
risks (Connor et al. 2006, pp. 87-88; Marvin-DiPasquale and Cox 2007,
p. 2). Regulation has reduced the use of some contaminants, only to be
replaced by other more potent alternative water-soluble chemicals such
as neonicotinoids, which have additional impacts on nontarget species
such as aquatic invertebrates and fish (Buzby et al. 2020, pp. 15-21).
Field-based toxicity is difficult to determine, as impacted fish
are not recovered in order to be examined (i.e., fish either die from
direct exposure and resulting disease, or are eaten). Risk of exposure
and effect, as determined by comparison to other species (e.g., delta
smelt and the introduced inland silverside (Menidia beryllina)),
potentially include direct effects on development, growth, and
reproduction; impacts resulting from impairments to bioenergetic
demands; and impaired locomotion, reducing feeding success, which can
lead to increased susceptibility to predation, disease, and entrainment
(Brander et al. 2012, p. 2854; Connon et al. 2009, p. 12; Hasenbein et
al. 2014, p. 696; Jeffries et al. 2015a, p. 17407; Jeffries et al.
2015b, p. 55; Cole et al. 2016, p. 219; DeCourten and Brander 2017, p.
2).
Pelagic Organism Decline (POD)
Between the years 2002 through 2004, abundance indices for multiple
fish species within the San Francisco Bay estuary declined abruptly in
what is known as the pelagic organism decline, or POD. Specifically,
the POD referred to a drop in survey catches of four fish species (Bay-
Delta longfin smelt, delta smelt, striped bass (Morone saxatilis), and
threadfin shad (Dorosoma petenense)) (Sommer et al. 2007, p. 273). The
POD event is generally recognized as a population step-decline for
numerous fish species in the estuary. The coincident declines of
multiple species suggested a possible common cause, but a single
mechanism for decline that applied to all four fish has not been
identified (MacNally et al. 2010, p. 1426; Thomson et al. 2010, pp.
1442-1443). As a result, researchers have focused on multiple causes,
from habitat changes, reductions in freshwater inflow, water
diversions, food resource changes, competition, predation, and
contaminants, as contributing to the POD (Sommer et al. 2007, pp. 271-
276; MacNally et al. 2010, p. 1418; Fong et al. 2016, pp. 20-21). As
outlined above, all of these factors have been identified as threats
impacting the Bay-Delta longfin smelt to varying degrees. Although the
POD event is not a threat in itself, but is instead most likely a
result of multiple threats, the subsequently smaller DPS population is
more susceptible to poor habitat conditions and has a reduced
capability of rebounding from lower abundance years.
Bay-Delta Longfin Smelt Current Condition
Current Abundance
Several long-term survey efforts have been established for
monitoring San Francisco Bay estuary fish populations including the
Bay-Delta longfin smelt. These established survey efforts include the
20-mm survey, the SFBS, and the FMWT. The 20-mm survey has been
conducted since 1995, and although it does not produce an abundance
index for Bay-Delta longfin smelt, we adapted the methods for the delta
smelt abundance index for the Bay-Delta longfin smelt. Our methods and
information on how we adapted the study information are outlined in the
current SSA report (Service 2024, appendix B). The SFBS has sampled
low-salinity to fully marine waters of the estuary using standardized
sampling methods since 1980. However, sampling was more sporadic in the
1990s and again in several recent years. The SFBS samples near bottom
as well as midwater to surface-oriented fishes (Feyrer et al. 2015,
Fig. 5, p. 3614) and provides separate abundance indices for ages 0, 1,
and 2+ Bay-Delta longfin
[[Page 61043]]
smelt. The longest of these survey efforts is the FMWT, which was
initiated in 1967 and has surveyed pelagic waters from the Delta into
San Pablo Bay monthly from September through December each year. The
FMWT captures mostly juvenile and adult fish 50-150 mm (2-6 in) in
length and has been used to monitor the abundance of sampled fish
species since the late 1970s (Stevens and Miller 1983, pp. 431-432). In
the case of Bay-Delta longfin smelt, the FMWT samples adults and
juveniles, most likely those returning from more marine environments to
low-salinity and freshwater areas associated with spawning. Similar
abundance estimates are reflected in the 20-mm survey, SFBS, and other
modeling efforts (Service 2024, section 3.2.1). Collectively, these
survey efforts encompass abundance estimates of all life stages of the
Bay-Delta longfin smelt in the estuary.
Figure 2 identifies FMWT abundance information for Bay-Delta
longfin smelt since its inception in 1967 with emphasis on the years
2000 to 2020. The FMWT time series is an index of fish numbers
returning to spawn in the San Francisco Bay Delta, which is an
indicator of abundance patterns as observed over this relatively longer
time interval presented to give a simplified visual presentation of
overall population trend during the last several decades. A more
detailed analysis of overall trends and attendant risk is discussed,
below.
[GRAPHIC] [TIFF OMITTED] TR30JY24.001
Population Trends and Risk of Quasi-Extinction
All the best available field surveys for documenting long-term
abundance trends indicate Bay-Delta longfin smelt numbers have
substantially declined over time, with current relative abundance
reflecting small fractions of the species' historical relative
abundance and representing a decline of three to four orders of
magnitude over the course of available historical abundance records.
Even considering the small periodic increases in numbers in occasional
years in the most recent survey results (past 20 years), the general
trend over time has been lower highs and lower lows in abundance for
the DPS. This finding supports the conclusion that abundance of all
life stages has declined substantially over the course of several
decades and that the overall decline has continued in recent years
(Service 2024, section 3.2). A meta-analysis of annual population
growth rates derived from the monitoring data showed that the DPS has a
negative population growth rate (Service 2024, section 3.2.2). Figure 3
displays quasi-extinction risk projections (including confidence
intervals) over time for the Bay-Delta longfin smelt from our risk
assessment (Tobias et al. 2023, fig. 4, p. 7; Service 2024, appendix
B).
[[Page 61044]]
[GRAPHIC] [TIFF OMITTED] TR30JY24.002
Effects of Threats Impacting the Bay-Delta Longfin Smelt
Reduced and altered freshwater flows into the estuary greatly
impact the physical and ecological processes important to Bay-Delta
longfin smelt spawning and larval rearing habitat. Reductions in
freshwater flow reduce the number of young that survive to later
reproduce. Reduced freshwater flows also require the DPS to move
farther inland to find appropriate low-salinity conditions for spawning
and rearing. Although management actions to limit the impact of water
diversions at export facilities have been implemented, this movement
farther inland makes the DPS's larvae and young more vulnerable to
entrainment as a result of water diversion from water export
facilities.
The amount of freshwater input into the estuary is dependent on
natural wet/dry precipitation patterns. These patterns have been
influenced by the effects of current climate change conditions, which
have resulted in more frequent, prolonged, and intense drought
conditions (reduced flows) and increased water temperatures (poor
habitat conditions). Freshwater flows into the estuary have also been
greatly influenced by human-caused alteration of rivers and streams
leading into the estuary as well as diversion and export of freshwater
from the estuary. These human-caused impacts of water management have
exacerbated the impacts of environmental variability of natural wet/dry
precipitation patterns.
In addition to altered habitat conditions for the Bay-Delta longfin
smelt, the available food resources for the DPS have also been severely
impacted. A rapid change to the zooplankton community in the estuary
beginning in the late 1980s along with the introduction of the
nonnative species such as the overbite clam and others has greatly
reduced the natural prey base for the DPS and replaced it with a
smaller nonnative mysid. Because the fish in the DPS continue to
exhibit very little variation in prey use despite the reduction in
natural prey availability, they are considered more susceptible to food
web changes than some other fishes. The decline in food resources is
likely affecting juvenile and adult longfin smelt growth and fitness as
well as increasing the effort needed to meet food resource demands.
After the review of the threats of predation, entrainment, and
contaminants, we have determined that they are not primary driving
factors currently influencing the Bay-Delta longfin smelt. However,
these threats are likely still contributing cumulatively to the overall
impacts acting on the DPS.
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have
analyzed the cumulative effects of identified threats and conservation
actions on the species. To assess the current and future condition of
the species, we evaluate the effects of all the relevant factors that
may be influencing the species, including threats and conservation
efforts. Because the SSA framework considers not just the presence of
the factors, but to what degree they collectively influence risk to the
entire species, our assessment integrates the cumulative effects of the
factors and replaces a standalone cumulative-effects analysis.
Resiliency, Redundancy, and Representation for the Bay-Delta Longfin
Smelt
In the current SSA report for the Bay-Delta longfin smelt (Service
2024, chapter 3), we evaluated the Bay-Delta longfin smelt's
resiliency, redundancy, and representation under our SSA framework
(Service 2016, entire).
Resiliency describes the ability of a species to withstand
stochastic disturbance. Because the Bay-Delta longfin smelt is a
single, intermixed population, we did not identify multiple resiliency
units but looked at the population as a whole. As discussed above, the
Bay-Delta longfin smelt is subject to multiple interacting threats,
including saltwater intrusion and reduced freshwater flows, that are
altering and degrading habitat conditions. The resulting impact of
these threats limits the extent, duration, and availability of
appropriate habitat conditions needed for spawning, rearing, and
ultimate recruitment of individuals into the population. These threats
include anthropogenic actions (such as freshwater management,
freshwater diversion, and physical alterations to the bathymetry of the
estuary) or poor or altered
[[Page 61045]]
environmental conditions (such as increased frequency and magnitude of
drought resulting from current climate change conditions). Disruptions
to the estuary's food web associated with reductions in freshwater flow
or introductions of nonnative species are also limiting resiliency for
the DPS.
Redundancy is the ability of a species to withstand catastrophic
events. The Bay-Delta longfin smelt is a single intermixed population
and occurs in areas within the San Francisco Bay estuary as dictated by
the extremely modified and altered habitat and resource conditions. The
San Francisco Bay estuary is also subject to extreme environmental
variability as a result of climate change conditions resulting in
increased temperatures and frequency, magnitude, and duration of
drought. As a result of these changes, the ability of the system and
organisms within the estuary to withstand catastrophic events and
rebound during periods of more favorable conditions is greatly reduced.
Large-scale estuary-wide ecosystem population collapses of fish and
native zooplankton have occurred in the estuary. Although no single
cause for the collapses has been identified, both native and nonnative
fish populations have not recovered. The result has been step-declines
of the Bay-Delta longfin smelt population size since the mid-1980s,
thereby reducing the redundancy of the DPS.
Representation describes the ability of a species to adapt to
changing environmental conditions over time. This definition includes
the ability of a species to adapt to both near-term and long-term
changes in its physical and biological environments. The Bay-Delta
longfin smelt population occurs in the San Francisco Bay estuary and is
a single, genetically indistinguishable population. The Bay-Delta
longfin smelt represents the southern extent of the species as a whole
and most likely is a source for populations along the coast north of
San Francisco Bay, but the number of individuals contributing to
populations further north has substantially declined. Due to ocean
currents and the species' poor swimming capability, populations north
of the San Francisco Bay are unlikely to have the ability to move south
and assist in reestablishing a population in the San Francisco Bay-
Delta once they have been extirpated from the San Francisco Bay-Delta.
The DPS's ability to adapt behaviorally to environmental changes (to
have adaptive capacity) is also limited. This limitation is exemplified
by the DPS's behavioral tendency of not adapting to food resource
changes. As discussed, food resources for the DPS have changed
significantly yet the DPS's behavior has not shifted to adapt to those
changes.
In our evaluation of the current condition of the Bay-Delta longfin
smelt, we evaluated several population viability analyses (PVAs) that
quantitatively derive probabilities of extinction over time based on
the DPS's historical and current abundance estimates (Service 2024;
appendix B). The PVAs used information from the existing suite of
surveys, including the FMWT, the 20-mm survey, and the SFBS (Service
2024, figure 3.11). The PVAs modeled extinction probability based on a
continuation of existing threats currently facing the DPS under varying
levels of population recruitment. Population growth rates were further
synthesized by conducting a meta-analysis on the growth rates of the
different surveys. The results of the count-based PVA meta-analysis
identified that the probability of quasi-extinction for the Bay-Delta
longfin smelt is estimated at 33 percent over 20 years and reaches 50
percent in 30 years (Service 2024, appendix B).
As a result of our review of the best scientific and commercial
data available on the Bay-Delta longfin smelt, we have determined that
the DPS's resiliency is low. Numerous decades of declining abundance
indices for the Bay-Delta longfin smelt document the inability of the
DPS to rebound during more favorable environmental conditions and
respond to the threats it is facing in the contemporary San Francisco
Bay estuary. The Bay-Delta longfin smelt also has extremely limited
redundancy because it effectively represents a single, small population
inhabiting the San Francisco Bay-Delta and nearshore ocean environment,
and because it continues to be impacted by large-scale stochastic
events and is subject to catastrophic events. We have determined that
the representation of the Bay-Delta longfin smelt is limited as well,
reflecting that same declining abundance trend and no discernible and
quantifiable compensatory adaptation to current ecological conditions.
Based on our evaluation of the current resiliency, redundancy, and
representation for the Bay-Delta longfin smelt, we conclude the current
ability of the DPS to maintain populations in the wild is low.
Future Conditions
As part of the SSA, we also developed future-condition scenarios to
capture the range of uncertainties regarding future threats and the
projected responses by the Bay-Delta longfin smelt. To assess the
future condition of the Bay-Delta longfin smelt, we used published
information related to the varying environmental conditions of the San
Francisco Estuary, including future climate change information and
projected increases in water demand, and how these changes may impact
how well the estuary can support the Bay-Delta longfin smelt into the
future. In our analyses, we considered two plausible future scenarios
based on representative concentration pathways (RCP) 4.5 and 8.5 as the
bookends for our analysis. The scenarios assessed climate change
information (temperature increases, changes in precipitation patterns,
sea-level rise) through 2100, as published information was available.
The information identified that declines in Bay-Delta longfin smelt
population abundance will continue into the future under both the RCP
4.5 and 8.5 scenarios. Because we determined that the current condition
of the Bay-Delta longfin smelt was consistent with an endangered
species (see Determination of the Bay-Delta Longfin Smelt's Status,
below), we are not presenting the results of the future scenarios in
this final rule. Please refer to the current SSA report (Service 2024,
chapter 4) for the full analysis of future scenarios.
Conservation Efforts and Regulatory Mechanisms
Numerous efforts have been initiated regarding conservation and
regulation of the San Francisco Bay estuary and its resources,
including managing water flows into and export from the estuary,
improving water quality, conducting habitat restoration, and
implementing measures or regulations to protect native fish. This
effort includes establishment of multiagency collaborations such as the
Interagency Ecological Program (IEP), which focuses on coordinating and
prioritizing science needs and research to meet responsibilities under
State and Federal regulatory requirements (IEP 2014, entire).
The State of California listed the longfin smelt in the San
Francisco Bay estuary and along the California Coast as a threatened
species under the California Endangered Species Act in 2009 (CDFW
2009a, entire; California Natural Diversity Database 2022, entire) and
has issued restrictions and requirements for the export of water for
the State Water Project (see Entrainment, Water Project Exports,
above). Several other fish species (delta smelt, several salmonid
species) are listed under both the Act and the California Endangered
Species Act, and the Service and NMFS have also issued biological
opinions regarding the effects to these species and their habitats for
[[Page 61046]]
delivery and export of water from the estuary (see Entrainment, Water
Project Exports, above). The State Water Board is responsible for
issuing water quality standards and monitors contaminants within the
estuary (see Contaminants, above). However, despite efforts such as
those identified above, the current condition of the estuary and
continued threats facing the estuary and Bay-Delta longfin smelt, such
as reduced freshwater inflow, severe declines in population size, and
disruptions to the DPS's food resources, have not been ameliorated.
Determination of the Bay-Delta Longfin Smelt's Status
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an endangered species or a
threatened species. The Act defines an ``endangered species'' as a
species in danger of extinction throughout all or a significant portion
of its range and a ``threatened species'' as a species likely to become
an endangered species within the foreseeable future throughout all or a
significant portion of its range. The Act requires that we determine
whether a species meets the definition of endangered species or
threatened species because of any 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.
Status Throughout All of Its Range
The Bay-Delta longfin smelt's current abundance and density
throughout the San Francisco Bay estuary have substantially declined.
Currently, the DPS exists in very low abundance despite periods when
appropriate habitat conditions, which typically would allow for
population rebounds, are available. The best scientific and commercial
information available and our analysis of that information revealed
that several threats are causing or contributing to this decline and
currently pose a meaningful risk to the viability of the DPS. These
threats have put the Bay-Delta longfin smelt largely into a state of
chronic population decline due to habitat loss (reduction in freshwater
flows into the estuary), which is exacerbated by limited food resources
and the impacts associated with climate change, thereby limiting its
resiliency and ability to withstand catastrophic events (reduced
redundancy). This decline in numbers of the Bay-Delta longfin smelt is
also a reflection of the DPS's ability to adapt to the ecosystem
changes.
As a result of the DPS's poor performance in adapting to the suite
of stressors acting upon it, we consider the Bay-Delta longfin smelt's
adaptive capacity and, therefore, its current representation to be low.
The Bay-Delta longfin smelt's continued reduced population size makes
the DPS vulnerable to varying habitat conditions from year to year due
to both anthropogenic and environmental conditions that are being
influenced by the effects of climate change. Historically, with a
larger population size, the DPS was more resilient to such stochastic
and catastrophic events due to its ability to rebound in abundance when
habitat conditions and resources would allow. The habitat changes,
limitations to food resources, and resulting small population size now
limit the DPS's ability to maintain its current population.
After evaluating threats to the DPS and assessing the cumulative
effect of the threats under the section 4(a)(1) factors, we find that
the threats facing the San Francisco Bay-Delta DPS of the longfin smelt
are current and ongoing and include habitat degradation and loss from
reduced freshwater flow into the estuary (Factor A), increased
intrusion of saltwater into spawning habitat areas (Factor A),
alteration of food resources and availability (Factor E), nonnative
species competition and food resource effects (Factor E), and the
effects associated with climate change such as increased temperatures
and frequency, magnitude, and duration of drought (Factor E). Because
these threats are ongoing and currently impacting the DPS, and have
already been shown to have caused a significant decline in the DPS's
current resiliency, redundancy, and representation, the DPS meets the
Act's definition of endangered status.
Thus, after assessing the best scientific and commercial
information available, we determine that the San Francisco Bay-Delta
DPS of the longfin smelt is in danger of extinction throughout all of
its range.
Status Throughout a Significant Portion of Its Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. We have determined that the San Francisco Bay-Delta DPS of
the longfin smelt is in danger of extinction throughout all of its
range and accordingly did not undertake an analysis of any significant
portions of its range. Because the San Francisco Bay-Delta DPS of the
longfin smelt warrants listing as endangered throughout all of its
range, our determination does not conflict with the decision in Center
for Biological Diversity v. Everson, 435 F. Supp. 3d 69 (D.D.C. 2020),
because that decision related to significant portion of the range
analyses for species that warrant listing as threatened, not
endangered, throughout all of their range.
Determination of Status
Our review of the best scientific and commercial information
available indicates that the San Francisco Bay-Delta DPS of the longfin
smelt meets the definition of an endangered species. Therefore, we are
listing the San Francisco Bay-Delta DPS of the longfin smelt as an
endangered species in accordance with sections 3(6) and 4(a)(1) of the
Act and our February 7, 1996, policy regarding distinct population
segments (61 FR 4722).
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition as a listed
species, planning and implementation of recovery actions, requirements
for Federal protection, and prohibitions against certain practices.
Recognition through listing results in public awareness, and
conservation by Federal, State, Tribal, and local agencies, foreign
governments, private organizations, and individuals. The Act encourages
cooperation with the States and other countries and calls for recovery
actions to be carried out for listed species. The protection required
by Federal agencies, including the Service, and the prohibitions
against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Section 4(f) of the Act calls for the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The goal of this process is to restore listed
species to a point where they are secure, self-sustaining, and
functioning components of their ecosystems.
[[Page 61047]]
The recovery planning process begins with development of a recovery
outline made available to the public soon after a final listing
determination. The recovery outline guides the immediate implementation
of urgent recovery actions while a recovery plan is being developed.
Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) may be
established to develop and implement recovery plans. The recovery
planning process involves the identification of actions that are
necessary to halt and reverse the species' decline by addressing the
threats to its survival and recovery. The recovery plan identifies
recovery criteria for review of when a species may be ready for
reclassification from endangered to threatened (``downlisting'') or
removal from protected status (``delisting''), and methods for
monitoring recovery progress. Recovery plans also establish a framework
for agencies to coordinate their recovery efforts and provide estimates
of the cost of implementing recovery tasks. Revisions of the plan may
be done to address continuing or new threats to the species, as new
substantive information becomes available. The recovery outline, draft
recovery plan, final recovery plan, and any revisions will be available
on our website as they are completed (https://www.fws.gov/program/endangered-species), or from our San Francisco Bay-Delta Fish and
Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
Once this species is listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost-share grants for non-Federal landowners, the
academic community, and nongovernmental organizations. In addition,
pursuant to section 6 of the Act, the State of California will be
eligible for Federal funds to implement management actions that promote
the protection or recovery of the San Francisco Bay-Delta DPS of the
longfin smelt. Information on our grant programs that are available to
aid species recovery can be found at: https://www.fws.gov/service/financial-assistance.
Please let us know if you are interested in participating in
recovery efforts for the San Francisco Bay-Delta DPS of the longfin
smelt. Additionally, we invite you to submit any new information on
this species whenever it becomes available and any information you may
have for recovery planning purposes (see FOR FURTHER INFORMATION
CONTACT).
Section 7 of the Act is titled Interagency Cooperation and mandates
all Federal action agencies to use their existing authorities to
further the conservation purposes of the Act and to ensure that their
actions are not likely to jeopardize the continued existence of listed
species or adversely modify critical habitat. Regulations implementing
section 7 are codified at 50 CFR part 402.
Section 7(a)(2) states that each Federal action agency shall, in
consultation with the Secretary, ensure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse
modification of designated critical habitat. Each Federal agency shall
review its action at the earliest possible time to determine whether it
may affect listed species or critical habitat. If a determination is
made that the action may affect listed species or critical habitat,
formal consultation is required (50 CFR 402.14(a)), unless the Service
concurs in writing that the action is not likely to adversely affect
listed species or critical habitat. At the end of a formal
consultation, the Service issues a biological opinion, containing its
determination of whether the Federal action is likely to result in
jeopardy or adverse modification.
Examples of discretionary actions for the San Francisco Bay-Delta
DPS of the longfin smelt that may be subject to consultation procedures
under section 7 are land management or other landscape-altering
activities on Federal lands administered by the Service, National Park
Service, Department of Defense, Reclamation, U.S. Army Corps of
Engineers, or U.S. Department of Agriculture, as well as actions on
State, Tribal, local, or private lands that require a Federal permit
(such as a permit from the U.S. Army Corps of Engineers under section
404 of the Clean Water Act (33 U.S.C. 1251 et seq.) or a permit from
the Service under section 10 of the Act) or that involve some other
Federal action (such as funding from the Federal Highway
Administration, Federal Aviation Administration, or the Federal
Emergency Management Agency). Federal actions not affecting listed
species or critical habitat--and actions on State, Tribal, local, or
private lands that are not federally funded, authorized, or carried out
by a Federal agency--do not require section 7 consultation. Federal
agencies should coordinate with the local Service Field Office (see FOR
FURTHER INFORMATION CONTACT) with any specific questions on section 7
consultation and conference requirements.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to endangered wildlife.
The prohibitions of section 9(a)(1) of the Act, and the Service's
implementing regulations codified at 50 CFR 17.21, make it illegal for
any person subject to the jurisdiction of the United States to commit,
to attempt to commit, to solicit another to commit or to cause to be
committed any of the following acts with regard to any endangered
wildlife: (1) import into, or export from, the United States; (2) take
(which includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect) within the United States, within the territorial
sea of the United States, or on the high seas; (3) possess, sell,
deliver, carry, transport, or ship, by any means whatsoever, any such
wildlife that has been taken illegally; (4) deliver, receive, carry,
transport, or ship in interstate or foreign commerce, by any means
whatsoever and in the course of commercial activity; or (5) sell or
offer for sale in interstate or foreign commerce. Certain exceptions to
these prohibitions apply to employees or agents of the Service, the
National Marine Fisheries Service, other Federal land management
agencies, and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits for endangered wildlife are codified at 50 CFR 17.22,
and general Service permitting regulations are codified at 50 CFR part
13. With regard to endangered wildlife, a permit may be issued: for
scientific purposes, for enhancing the propagation or survival of the
species. The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
It is the policy of the Services, as published in the Federal
Register on July 1, 1994 (59 FR 34272), to identify,
[[Page 61048]]
to the extent known at the time a species is listed, specific
activities that will not be considered likely to result in violation of
section 9 of the Act. To the extent possible, activities that will be
considered likely to result in violation will also be identified in as
specific a manner as possible. The intent of this policy is to increase
public awareness of the effect of a listing on proposed and ongoing
activities within the range of the species.
As discussed above, certain activities that are prohibited under
section 9 may be permitted under section 10 of the Act. In addition, to
the extent currently known, the following activities will not be
considered likely to result in violation of section 9 of the Act: (1)
take of the longfin smelt outside the range of the DPS as identified in
figure 1 above; (2) take as a result of recreational fishing as
permitted by the State of California; or (3) recreational boating on
open-water areas of the San Francisco Bay-Delta Estuary.
This list is intended to be illustrative and not exhaustive;
additional activities that will not be considered likely to result in
violation of section 9 of the Act may be identified during coordination
with the local field office, and in some instances (e.g., with new
information), the Service may conclude that one or more activities
identified here will be considered likely to result in violation of
section 9.
To the extent currently known, the following is a list of examples
of activities that will be considered likely to result in violation of
section 9 of the Act in addition to what is already clear from the
descriptions of the prohibitions found at 50 CFR 17.21: (1) handling or
collecting individuals of the DPS; (2) destruction/alteration of the
Bay-Delta longfin smelt's habitat by discharge of fill material,
dredging, draining, ditching, or stream channelization or diversion;
(3) unauthorized diversion or alteration of surface flow into the San
Francisco Bay-Delta estuary by removal of freshwater from rivers,
streams, wetlands, and other aquatic features; (4) introduction of
contaminants that may degrade water quality of the San Francisco Bay-
Delta estuary; or (5) introduction of nonnative species that compete
with or prey upon the Bay-Delta longfin smelt or alter food resources
for the DPS.
This list is intended to be illustrative and not exhaustive;
additional activities that will be considered likely to result in
violation of section 9 of the Act may be identified during coordination
with the local field office, and in some instances (e.g., with new or
site-specific information), the Service may conclude that one or more
activities identified here will not be considered likely to result in
violation of section 9.
Questions regarding whether specific activities would constitute
violation of section 9 of the Act should be directed to the San
Francisco Bay-Delta Fish and Wildlife Office (see FOR FURTHER
INFORMATION CONTACT).
II. Critical Habitat
Section 4(a)(3) of the Act and implementing regulations (50 CFR
424.12) require that we designate critical habitat at the time a
species is determined to be an endangered or threatened species, to the
maximum extent prudent and determinable. In the October 7, 2022,
proposed listing rule (87 FR 60957 at 60970), we determined that
designation of critical habitat was prudent but not determinable
because specific information needed to analyze the impacts of
designation was lacking. Since the publication of the proposed listing
rule, we have obtained the necessary information and are in the process
of developing a proposed critical habitat designation for the Bay-Delta
longfin smelt. We plan to publish a proposed critical habitat rule in
the near future and complete a final designation as required by
sections 4(a)(3) and 4(b)(6)(C)(ii) of the Act.
Required Determinations
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
It is our position that, outside the jurisdiction of the U.S. Court
of Appeals for the Tenth Circuit, we do not need to prepare
environmental analyses pursuant to the National Environmental Policy
Act (42 U.S.C. 4321 et seq.) in connection with regulations adopted
pursuant to section 4(a) of the Act. We published a notice outlining
our reasons for this determination in the Federal Register on October
25, 1983 (48 FR 49244). This position was upheld by the U.S. Court of
Appeals for the Ninth Circuit (Douglas County v. Babbitt, 48 F.3d 1495
(9th Cir. 1995), cert. denied 516 U.S. 1042 (1996)).
Government-to-Government Relationship With Tribes
In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951, May 4, 1994), Executive Order 13175
(Consultation and Coordination with Indian Tribal Governments), the
President's memorandum of November 30, 2022 (Uniform Standards for
Tribal Consultation; 87 FR 74479, December 5, 2022), and the Department
of the Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with federally recognized
Tribes and Alaska Native Corporations on a government-to-government
basis. In accordance with Secretaries' Order 3206 of June 5, 1997
(American Indian Tribal Rights, Federal-Tribal Trust Responsibilities,
and the Endangered Species Act), we readily acknowledge our
responsibilities to work directly with Tribes in developing programs
for healthy ecosystems, to acknowledge that Tribal lands are not
subject to the same controls as Federal public lands, to remain
sensitive to Indian culture, and to make information available to
Tribes. No Tribal lands were identified within the range of the Bay-
Delta longfin smelt, and we did not receive any information during our
development of the SSA report for the DPS or the two open public
comment periods. We will continue to reach out and coordinate with
Tribal entities during the development of our recovery planning and
critical habitat designation processes for the Bay-Delta longfin smelt.
References Cited
A complete list of references cited in this rulemaking is available
on the internet at https://www.regulations.gov and upon request from
the San Francisco Bay-Delta Fish and Wildlife Office (see FOR FURTHER
INFORMATION CONTACT).
Authors
The primary authors of this rule are the staff members of the Fish
and Wildlife Service's Species Assessment Team and the San Francisco
Bay-Delta Fish and Wildlife Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Plants,
Reporting and recordkeeping requirements, Transportation, Wildlife.
Signing Authority
Martha Williams, Director of the U.S. Fish and Wildlife Service,
approved this action on June 14, 2024, for publication. On July 22,
2024, Martha Williams authorized the undersigned to sign the document
electronically and submit it to the Office of the Federal Register for
publication as an official document of the U.S. Fish and Wildlife
Service.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as set forth below:
[[Page 61049]]
PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245,
unless otherwise noted.
0
2. Amend Sec. 17.11 in paragraph (h), in the List of Endangered and
Threatened Wildlife, by adding an entry for ``Smelt, longfin [San
Francisco Bay-Delta DPS]'' in alphabetical order under FISHES to read
as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
----------------------------------------------------------------------------------------------------------------
Listing citations and
Common name Scientific name Where listed Status applicable rules
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Fishes
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Smelt, longfin [San Francisco Spirinchus U.S.A. (CA)....... E 89 FR [INSERT FIRST
Bay-Delta DPS]. thaleichthys. PAGE OF FEDERAL
REGISTER PUBLICATION],
7/30/2024.
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Madonna Baucum,
Regulations and Policy Chief, Division of Policy, Economics, Risk
Management, and Analytics of the Joint Administrative Operations, U.S.
Fish and Wildlife Service.
[FR Doc. 2024-16380 Filed 7-29-24; 8:45 am]
BILLING CODE 4333-15-P