                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


NATURAL RESOURCES DEFENSE             No. 14-16375
COUNCIL, INC.; HUMANE
SOCIETY OF THE UNITED STATES;            D.C. No.
CETACEAN SOCIETY                    3:12-cv-05380-EDL
INTERNATIONAL; OCEAN
FUTURES SOCIETY; JEAN-
MICHEL COUSTEAU; MICHAEL                OPINION
STOCKER,
           Plaintiffs-Appellants,

               v.

PENNY PRITZKER, Secretary,
U.S. Department of Commerce;
NATIONAL MARINE FISHERIES
SERVICE; EILEEN SOBECK,
Assistant Administrator for
Fisheries; KATHRYN D.
SULLIVAN, Administrator of the
National Oceanic and
Atmospheric Administration;
RAY MABUS, Secretary of the
Navy; JONATHAN GREENERT,
Admiral, Chief of Naval
Operations,
           Defendants-Appellees.
2                       NRDC V. PRITZKER

        Appeal from the United States District Court
            for the Northern District of California
      Elizabeth D. Laporte, Magistrate Judge, Presiding

            Argued and Submitted March 17, 2016
                  San Francisco, California

                        Filed July 15, 2016

         Before: John T. Noonan, Ronald M. Gould,
         and Michelle T. Friedland, Circuit Judges.

                     Opinion by Judge Gould


                           SUMMARY*


                       Environmental Law

    The panel reversed the district court’s grant of summary
judgment to federal defendants in a case relating to the proper
scope under the Marine Mammal Protection Act (“MMPA”)
of mitigation measures required to protect marine mammals
when the responsible federal agency, the National Marine
Fisheries Service, sought to approve incidental “take” relating
to military readiness activities, namely, the Navy’s peacetime
use of Surveillance Towed Array Sensor System Low
Frequency Active sonar.




  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                     NRDC V. PRITZKER                        3

    The Fisheries Service most recently authorized incidental
take of marine mammals from Low Frequency Active sonar
use for five years beginning in 2012 in a Final Rule.

    The panel held that the 2012 Final Rule did not establish
means of “effecting the least practicable adverse impact on”
marine mammal species, stock and habitat, as was
specifically required by the MMPA. The panel further held
that the Fisheries Service impermissibly conflated the “least
practicable adverse impact” standard with the “negligible
impact” finding; and concluded that to authorize incidental
take, the Fisheries Service must achieve the “least practicable
adverse impact” standard in addition to finding a negligible
impact.

    The panel held that the Fisheries Service did not give
adequate protection to areas of the world’s oceans flagged by
its own experts as biologically important, based on the
present lack of data sufficient to meet the Fisheries Service’s
designation criteria. The panel remanded for further
proceedings.
4                      NRDC V. PRITZKER

                            COUNSEL

Michael E. Wall (argued), Natural Resources Defense
Council, San Francisco, California; Joel R. Reynolds and
Giulia C.S. Good Stefani, Natural Resources Defense
Council, Santa Monica, California; Sara C. Tallman, Natural
Resources Defense Council, Chicago, Illinois; Barbara J.
Chisholm, Altshuler Berzon LLP, San Francisco, California;
for Plaintiffs-Appellants.

Emily Polachek (argued), Kevin W. McArdle, Ty Bair, J.
David Gunter II, and Andrew C. Mergen, Trial Attorneys;
John C. Cruden, Assistant Attorney General; Environment
and Natural Resources Division, Department of Justice,
Washington, D.C.; for Defendants-Appellees.


                             OPINION

GOULD, Circuit Judge:

    This appeal presents a challenging question relating to the
proper scope under the Marine Mammal Protection Act
(MMPA) of mitigation measures required to protect marine
mammals when the responsible federal agency, the National
Marine Fisheries Service (NMFS), seeks to approve
incidental “take” relating to military readiness activities. The
appeal concerns the Navy’s peacetime use of Surveillance
Towed Array Sensor System Low Frequency Active sonar
(SURTASS LFA or “LFA sonar”).1 Congress has required


    1
     The limitations of government activity under the MMPA that we
review here do not apply in the context of a war in which the Navy must
locate enemy submarines at the risk of civilian casualties or maritime
                         NRDC V. PRITZKER                                  5

that NMFS set limitations on activities that may cause
“take”—i.e. harm to marine mammals— such as military
readiness activities, to reduce their impacts to the least
practicable level.2 The question here is whether NMFS


property destruction if it fails. A maxim made famous by Marcus Tullius
Cicero is that in times of war, the laws fall silent (in Latin “silent enim
leges inter arma”). Cicero in Twenty-Eight Volumes, Volume XIV 16–17
(N.H. Watts trans., Harvard University Press 1972). Here, as in prior
disputes on the Navy’s LFA sonar use, the parties’ disagreement concerns
peacetime use of LFA sonar. See Nat. Res. Def. Council v. Evans, 279 F.
Supp. 2d 1129, 1138 (N.D. Cal. 2003) (“It is true that only peacetime use
of this new sonar system is at issue; the Navy is free to use the system
without restriction in time of war or heightened threat.”). Moreover, in
2003 Congress added a general national defense exception to the MMPA,
under which “[t]he Secretary of Defense, after conferring with the
Secretary of Commerce, the Secretary of the Interior, or both, as
appropriate, may exempt any action or category of actions undertaken by
the Department of Defense or its components from compliance with any
requirement of this chapter, if the Secretary determines that it is necessary
for national defense.” 16 U.S.C. § 1371(f)(1). The exemption cannot last
longer than two years, and the Secretary must report it to the Committees
on Armed Services in both the House of Representatives and the Senate.
16 U.S.C. §§ 1371(f)(2)(B) & (f)(4). We are confident that the mitigation
measures the MMPA requires do not infringe on the Navy’s capacity to
defend the United States during wartime or heightened threats to national
security.
 2
    It has recently been reported that increased numbers of Russian attack
submarines are being deployed to patrol the coastlines of Scandinavia,
Scotland, the Mediterranean Sea and the North Atlantic in what military
officials describe as a significantly increased presence aimed at contesting
American and NATO undersea dominance. Eric Schmitt, Russia Bolsters
its Submarine Fleet, and Tensions with U.S. Rise, N.Y. Times (April 20,
2016), http://www.nytimes.com/2016/04/21/world/europe/russia-bolsters-
submarine-fleet-and-tensions-with-us-rise.html.         This development
underscores the importance of effective military readiness training so that
if LFA sonar is needed in a war, the Navy will be prepared to use it
effectively. The importance of military readiness activities should not be
6                       NRDC V. PRITZKER

correctly authorized the incidental take of marine mammals
in connection with the Navy’s use of LFA sonar for training,
testing, and routine operations. NMFS determined that the
incidental take of a specified number of marine mammals by
use of LFA sonar would have a negligible impact on the
marine mammal species, and Plaintiffs do not appeal that
determination. Plaintiffs appeal only the district court’s
conclusion that NMFS’s mitigation measures satisfied the
MMPA’s least practicable adverse impact standard.3

    The district court granted summary judgment to
Defendants on the issue of MMPA compliance. It held that
“[e]ven if the impact on the population is negligible under
16 U.S.C. §1371(a)(5)(A)(i)(I), the agency could still impose
mitigation that would further reduce the impact on the
population to the least practicable [level] under
16 U.S.C.§ 1371(a)(5)(A)(i)(II)(aa).” The district court
further held that “[t]he requirement to adopt measures to
ensure the ‘least practicable adverse impact’ on marine
mammals is ‘a stringent standard,’” and that though the
agency has discretion to choose among possible mitigation
measures, it cannot exercise that discretion to vitiate that
stringent standard. We agree with those principles. But,
because we disagree with the district court’s methodology
and with its conclusion that the least practicable adverse
impact standard was satisfied, we reverse.


denied or minimized. But the need for them makes it all the more
important that NMFS craft mitigation measures that comply with the
statutory commands.
    3
    Plaintiffs initially brought claims under not only the MMPA, but also
the Endangered Species Act (ESA) and the National Environmental Policy
Act (NEPA). But rulings on the ESA and NEPA claims were not
appealed, so our sole concern is the application of the MMPA.
                     NRDC V. PRITZKER                          7

                               I

    The Navy’s plans for use of LFA sonar, as approved by
NMFS, have gone through several iterations, resulting in
increased protection for marine mammals. We have every
reason to believe that the Navy has been deliberate and
thoughtful in its plans to follow NMFS guidelines and limit
unnecessary harassment and harm to marine mammals. But
the question is whether NMFS has satisfied the Congressional
mandate that mitigation measures ensure the “least
practicable adverse impact” on marine mammals.

    The MMPA was enacted in response to Congressional
concern that marine mammal species and population stocks
were in danger of extinction or depletion due to human
activity. 16 U.S.C. § 1361(1). The MMPA aims to balance
marine mammal protection with other strong but opposing
interests, such as national security. To prevent marine
mammal species and population stocks from diminishing
“beyond the point at which they cease to be a significant
functioning element in the ecosystem,” the MMPA broadly
prohibits “take” of marine mammals. 16 U.S.C. §§ 1361(2),
1371. “Take” means to harass, hunt, capture, or kill any
marine mammal. 16 U.S.C. § 1362(13).

    There are exceptions to the MMPA take prohibition. The
MMPA allows NMFS to authorize take of “small numbers”
of marine mammals, incidental to a specified activity, for up
to five years.4 16 U.S.C. § 1371(a)(5)(A)(i). NMFS may


 4
   The MMPA delegated authority for oceanic marine mammals to the
Secretary of the department in which the National Oceanic and
Atmospheric Administration (NOAA) operates. 16 U.S.C. § 1362(12).
NOAA is part of the U.S. Department of Commerce. NMFS, a division
8                       NRDC V. PRITZKER

authorize such incidental take if the take meets two
requirements. First, NMFS must find that the total authorized
take during the five-year period “will have a negligible
impact on such species or stock[.]”               16 U.S.C.
§ 1371(a)(5)(A)(i)(I). Second, NMFS must prescribe
regulations setting forth “permissible methods of taking
pursuant to such activity, and other means of effecting the
least practicable adverse impact on such species or stock and
its habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance[.]” 16 U.S.C.
§ 1371(a)(5)(A)(i)(II)(aa). The “least practicable adverse
impact” standard applies both to “permissible methods of
taking pursuant to” the activity causing incidental take and to
“other means” of reducing incidental take. See Evans, 279 F.
Supp. 2d at 1142 (NMFS’s rulemaking must, among other
things, “prescribe methods and means of effecting the ‘least
practicable adverse impact’ on species and stock and their
habitat” (quoting 16 U.S.C. § 1371(a)(5)(A))).

     In connection with peacetime activities such as use of
LFA sonar for training, testing, and routine operations,
Congress struck a balance to permit incidental take of marine
mammals caused by deployment of LFA sonar or other
techniques that might incidentally harm whales and other
marine mammals, so long as the incidental take from the
activity has a negligible impact on the species or stock
involved, and so long as mitigation measures were fashioned
to limit harm to the marine mammals to the “least practicable


of NOAA, is responsible for species of the order Cetacea, whales and
dolphins, and the order Pinnipedia, seals and sea lions, except for
walruses. The U.S. Department of the Interior is responsible for all other
marine mammals including manatees, polar bears, sea otters, and
walruses. Id.
                        NRDC V. PRITZKER                              9

adverse impact.” As the agency with delegated authority to
implement the MMPA, NMFS is bound by these
congressional mandates.

                                  II

    Whales, dolphins, walruses, and other marine mammals
rely on perceptions of underwater sound for vital biological
functions such as catching prey, navigating, and
communicating. The United States Navy operates LFA sonar
vessels around the world for another vital purpose: to protect
the nation from increasingly quiet foreign submarines. The
Navy has determined that LFA sonar is the most effective
way to detect potentially hostile submarines.5 LFA sonar
uses a set of transmitting projectors that are suspended by a
cable from an ocean surveillance ship. The projectors
produce low-frequency sound pulses at an intensity of
approximately 215 decibels (dB), in sequences that last 60
seconds on average. LFA sonar can detect enemy ships day
and night in varied weather conditions over hundreds of
miles.

   LFA sonar, while beneficial to national defense, can harm
many marine mammal species, particularly “low-frequency
hearing specialists” such as baleen whales, but also sperm


  5
    LFA sonar can detect submarines over much larger distances than mid-
frequency active sonar, which the Navy has used since World War II,
because lower frequencies suffer less attenuation in seawater. Kristina
Alexander, Whales and Sonar: Environmental Exemptions for the Navy’s
Mid-Frequency Active Sonar Training, Congressional Research Service,
February 18, 2009, available at https://www.fas.org/sgp/crs/
weapons/RL34403.pdf. In contrast, passive sonar systems merely use
hydrophones to detect, amplify, and identify sounds from other sources.
Id.
10                      NRDC V. PRITZKER

whales and pinnipeds such as seals and walruses. LFA sonar
disrupts the hearing of these animals and can cause physical
injury at sound levels greater than 180 dB. Effects from
exposures below 180 dB can cause short-term disruption or
abandonment of natural behavior patterns. These behavioral
disruptions can cause affected marine mammals to stop
communicating with each other, to flee or avoid an ensonified
area, to cease foraging for food, to separate from their calves,
and to interrupt mating. LFA sonar can also cause heightened
stress responses from marine mammals. Such behavioral
disruptions can force marine mammals to make trade-offs
like delaying migration, delaying reproduction, reducing
growth, or migrating with reduced energy reserves.

    The MMPA classifies such forms of harassment in two
categories: “Level A” harassment and “Level B” harassment.
With respect to “military readiness activit[ies],”6 such as the
Navy’s use of LFA sonar, the MMPA defines Level A


  6
    The MMPA uses the definition of “military readiness activity” in Pub.
L. 107-314 § 315(f)(1). See 16 U.S.C. § 1371(a)(5)(A)(ii). The term
“includes (A) all training and operations of the Armed Forces that relate
to combat; and (B) the adequate and realistic testing of military
equipment, vehicles, weapons, and sensors for proper operation and
suitability for combat use.” Pub. L. 107-314 § 315(f)(1). Military
readiness activities are also the subject of 2003 amendments to the
MMPA, which specify that NMFS “shall include consideration of
personnel safety, practicability of implementation, and impact on the
effectiveness of the military readiness activity” in making a “least
practicable adverse impact” determination.            National Defense
Authorization Act for Fiscal Year 2004, H.R. Cong. Rep. 108-354,
reprinted in 2003 U.S.C.C.A.N. 1407 (Nov. 7, 2003); see 16 U.S.C.
§ 1371(a)(5)(A)(ii). These changes define considerations relevant to
determining the practicability of mitigation measures, but they do not
eliminate the requirement that the “adverse impact on such species or
stock” must be mitigated to the greatest extent practicable.
                     NRDC V. PRITZKER                         11

harassment as “any act that injures or has the significant
potential to injure a marine mammal or marine mammal stock
in the wild.” 16 U.S.C. § 1362(18)(B), (C). Level A
harassment happens when marine mammals are exposed to
sound pulses of 180 dB or greater. Level B harassment, less
severe, includes “any act that disturbs or is likely to disturb a
marine mammal or marine mammal stock in the wild by
causing disruption of natural behavioral patterns, including,
but not limited to, migration, surfacing, nursing, breeding,
feeding, or sheltering, to a point where such behavioral
patterns are abandoned or significantly altered.” 16 U.S.C.
§ 1362(18)(B), (D). Level B harassment is caused by sound
levels below 180 dB. Sound intensities of 165 dB subject
marine mammals to a 50% risk of Level B harassment. And
sound intensities as low as 120 dB can still cause “increasing
probability of avoidance and other behavioral effects.” Stated
another way, Level A harassment involves activities that
directly injure or are likely to injure marine mammals. By
contrast, Level B harassment involves activities that interfere
with normal behavioral patterns of the marine mammals, with
the risk of indirect harm that creates.

    NMFS most recently authorized incidental take of marine
mammals from LFA sonar use for five years beginning in
2012. See Taking and Importing Marine Mammals: Taking
Marine Mammals Incidental to U.S. Navy Operations of
Surveillance Towed Array Sensor System Low Frequency
Active Sonar, 77 Fed. Reg. 50290 (Aug. 20, 2012) (2012
“Final Rule”). This authorization, and the accompanying
mitigation measures, apply to the Navy’s routine training and
testing and use of LFA sonar during military operations in
areas of the Pacific, Atlantic, and Indian Oceans and the
Mediterranean Sea between 2012–2017. 77 Fed. Reg. at
50291. They do not constrict the Navy’s operations during a
12                      NRDC V. PRITZKER

war or active military engagement. The 2012 Final Rule
provides guidelines for incidental take regulations for LFA
sonar use on a maximum of four Navy vessels in 70–75% of
the world’s oceans, covering the Pacific, Atlantic, and Indian
Oceans, and the Mediterranean Sea. Id. at 50303. Each LFA
sonar vessel may perform up to 240 days per year of active
sonar operations. Id. at 50292. The 2012 Final Rule allows
the Navy to incidentally take, through Level A harassment,
up to six baleen whales, 25 toothed whales, and 25 pinnipeds
annually. Id. at 50313, 50317. The Navy may also take,
through Level B harassment, up to 12% of the entire stock of
every affected marine mammal species every year. Id. at
50316–17.

     The 2012 Final Rule contains three mitigation measures
intended to minimize the impact of this incidental take on
marine mammal species, stock, and habitat. First, there is a
requirement that the Navy shut down or delay LFA sonar use
if it detects a marine mammal near a sonar vessel. This
requirement instructs the Navy to use a combination of
human lookouts and a dedicated marine mammal detection
system (called the “High Frequency Marine Mammal
Monitoring” system) to detect nearby marine mammals. If a
marine mammal is detected within two kilometers of an LFA
sonar vessel, the Navy must delay or suspend sonar
transmissions. The intensity of an LFA sonar pulse drops
from 215 dB at the source to 175 dB at two kilometers.7
Consequently, NMFS expects this two-kilometer shutdown
zone to almost completely prevent Level A harassment,


 7
   Decibels measure sound intensity on a logarithmic scale. For example,
a sound measuring 180 dB is approximately ten times more intense than
a 170 dB sound. Nat. Res. Def. Council v. Evans, 232 F. Supp. 2d 1003,
1014 (N.D. Cal. 2002).
                     NRDC V. PRITZKER                       13

including physical injury, which occurs only at intensities of
180 dB or greater.

    Second, the Final Rule prohibits the Navy from creating
LFA sonar pulses of 180 dB or greater within a “coastal
exclusion zone” extending 22 km, or about 12 nautical miles
(nm), of any coastline. Continental shelf waters are
recognized as biologically important to marine mammals, and
the district court previously ordered NMFS to protect these
waters even in areas without site-specific data. Evans, 279 F.
Supp. 2d at 1164.

   Third, the Final Rule prohibits the Navy from creating
LFA sonar pulses of 180 dB or greater within a kilometer of
several designated “offshore biologically important areas”
(OBIAs). OBIAs are marine protected areas providing
marine mammals with relatively low-noise environments, as
LFA sonar pulses moving in from the periphery of an OBIA
gradually dissipate.

                             III

    The key provisions of the Administrative Procedure Act
(APA) require the court to hold unlawful and set aside a final
order of an agency if the order is “arbitrary, capricious, an
abuse of discretion, or otherwise not in accordance with law.”
See 5 U.S.C. § 706(2)(A). The Supreme Court has made
clear that the federal courts should give deference to federal
agency decisions in several ways. Motor Vehicle Mfrs. Ass’n
of U.S., Inc. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29,
43 (1983). First, we generally only set aside a final agency
action if the agency decision is “arbitrary and capricious,” or
“not in accordance with law.” The general rule elaborating
14                       NRDC V. PRITZKER

the meaning of “arbitrary and capricious” was stated in State
Farm as follows:

         Normally, an agency rule would be arbitrary
         and capricious if the agency has relied on
         factors which Congress has not intended it to
         consider, entirely failed to consider an
         important aspect of the problem, offered an
         explanation for its decision that runs counter
         to the evidence before the agency, or is so
         implausible that it could not be ascribed to a
         difference in view or the product of agency
         expertise.

463 U.S. at 43.

    Further, if the agency itself did not provide reasons to
satisfy the above standard, we will not use our own line of
reasoning to bolster the agency decision on grounds that it did
not include in its reasoning. See, e.g., SEC v. Chenery Corp.,
332 U.S. 194, 196 (1947).8




  8
     This case comes before us on summary judgment, not a decision at
trial. We review a district court’s grant of summary judgment de novo.
Szajer v. City of Los Angeles, 632 F.3d 607, 610 (9th Cir. 2011). We view
in the light most favorable to Plaintiffs evidence of harm to marine
mammals caused by LFA sonar and evidence of whether required
mitigation measures achieve the “least practicable adverse effect” on the
marine mammals, and we must determine “whether there are any genuine
issues of material fact and whether the district court correctly applied the
relevant substantive law.” Id. (quoting Universal Health Servs., Inc. v.
Thompson, 363 F.3d 1013, 1019 (9th Cir. 2004)).
                     NRDC V. PRITZKER                       15

                              IV

    The conflict in this case is about whether the mitigation
measures set forth in NMFS’s 2012 Final Rule achieve the
required “least practicable adverse impact” on marine
mammal species, stock, and habitat.              16 U.S.C.
§ 1371(a)(5)(A)(i)(II)(aa). In Evans, 279 F. Supp. 2d at 1159,
which applied the “least practicable adverse impact” standard
on summary judgment to LFA sonar operations authorized by
NMFS’s 2002 Final Rule, the district court held: “In
requiring the agency to adopt measures to ensure the ‘least
practicable adverse impact’ on marine mammals, Congress
imposed a stringent standard. Although the agency has some
discretion to choose among possible mitigation measures, it
cannot exercise that discretion to vitiate this stringent
standard.” We agree with this formulation.

    Defendants on appeal advance several arguments for why
NMFS was not required to comply with this stringent
standard in authorizing the Final Rule. First, they contend
that once NMFS makes a negligible impact finding, it “must
allow the activity,” and the “only question at that point is
what mitigation measures will be required for the proposed
activity to go forward.” We disagree. To ascertain the
meaning of the “least practicable adverse impact” standard,
we look to the statutory text, and we must “presume that [the]
legislature says in a statute what it means and means in a
statute what it says there.” BedRoc Ltd., LLC v. United
States, 541 U.S. 176, 183 (2004) (alteration in original)
(quoting Conn. Nat’l Bank v. Germain, 503 U.S. 249, 253–54
(1992)). It is clear from the statute’s text—which sets forth
a two-part requirement for authorization of incidental take,
see 16 U.S.C. § 1371(a)(5)(A)(i)—that mitigation sufficient
to achieve the “least practicable adverse impact” is not a mere
16                    NRDC V. PRITZKER

secondary issue, but rather an independent, threshold
statutory requirement. As with a “negligible impact” finding,
it is central to whether NMFS can authorize incidental take in
the first place. Congress’s mandate that NMFS must find
negligible impact “and” set forth regulations to minimize
adverse impact in order to authorize incidental take makes the
independent nature of these requirements clear. 16 U.S.C.
§ 1371(a)(5)(A)(i)(I) (emphasis added). Defendants’ contrary
reading of the statute is “at odds with one of the most basic
interpretive canons, that ‘[a] statute should be construed so
that effect is given to all its provisions, so that no part will be
inoperative or superfluous, void or insignificant[.]’” Corley
v. United States, 556 U.S. 303, 314 (2009) (alteration in
original) (quoting Hibbs v. Winn, 542 U.S. 88, 101 (2004)).

    Defendants next contend that the mitigation requirement
is superfluous; in their words, the agency “cannot mitigate
adverse population-level impacts to any degree less than
zero.” This argument is based on a misreading of the
agency’s own implementing regulations. These regulations
define “negligible impact” as “an impact resulting from the
specified activity that cannot be reasonably expected to, and
is not reasonably likely to, adversely affect the species or
stock through effects on annual rates of recruitment or
survival.” 50 C.F.R. § 216.103. The inquiry as to “negligible
impact” is thus focused on population-level effects—i.e. on
“annual rates of recruitment or survival.” Defendants seek to
import that population-level focus to the “least practicable
adverse impact” standard, but the regulations do not even
define that standard, let alone limit its focus to population-
level effects. Instead, the MMPA itself simply requires
NMFS to prescribe regulations setting forth “means of
effecting the least practicable adverse impact on such species
or stock and its habitat,” both of which could be adversely
                     NRDC V. PRITZKER                       17

affected by activities that do not necessarily affect annual
rates of recruitment or survival.                 16 U.S.C.
§ 1371(a)(5)(A)(i)(II)(aa). The statute is properly read to
mean that even if population levels are not threatened
significantly, still the agency must adopt mitigation measures
aimed at protecting marine mammals to the greatest extent
practicable in light of military readiness needs.

    We conclude that NMFS is required to prescribe
regulations to achieve the “least practicable adverse impact”
before it can authorize incidental take. While NMFS’s
finding that LFA sonar operations will have a “negligible
impact” on marine mammal populations is a required element
for approval of incidental take, it is not a substitute for an
analysis of whether the proposed mitigation measures in the
2012 Final Rule reduce the impact of incidental take on
marine mammals to the lowest level practicable. Compliance
with the “negligible impact” requirement does not mean there
was compliance with the “least practicable adverse impact”
standard during rulemaking. Moreover, NMFS did not in
agency proceedings contend that its finding of negligible
impact on populations meant it satisfied the “least practicable
adverse impact” standard for mitigation. NMFS makes that
argument only in its briefing on appeal, “underscor[ing] the
absence of an adequate explanation in the administrative
record itself.” Humane Soc. of U.S. v. Locke, 626 F.3d 1040,
1050 (9th Cir. 2010); see also Chenery, 332 U.S. at 196; State
Farm, 463 U.S. at 50 (explaining that “post hoc
rationalizations for agency action” are no substitute for “the
basis articulated by the agency itself”).

   Having determined that NMFS was required to
promulgate regulations to effect the “least practicable adverse
impact,” we turn to examining what that standard requires
18                      NRDC V. PRITZKER

and whether the 2012 Final Rule complied with it. In seeking
the meaning of “least practicable adverse impact,” we
naturally start with the language of the statute. United States
v. Am. Trucking Ass’ns, 310 U.S. 534, 543 (1940) (“There is,
of course, no more persuasive evidence of the purpose of a
statute than the words by which the legislature undertook to
give expression to its wishes.”). “Practicable” normally
means that something is capable of being done, or practical
an d effect ive.           Pr act i cabl e, OED Onl i ne,
http://www.oed.com/view/Entry/149217; Practicable,
Merriam-Webster, http://www.merriam-webster.com/
dictionary/practicable. In context, a mitigation measure that
is practicable in reducing the impact of military readiness
activities on marine mammals must be both effective in
reducing impact, but also not so restrictive of military activity
as to unduly interfere with the government’s legitimate needs
for military readiness activities.9

    NMFS in its Final Rule did not appear to disagree with
this formulation of the “least practicable adverse impact”
standard. In discussing its evaluation of the standard, it
stated:

         We have reviewed the Navy’s proposed
         SURTASS LFA sonar activities and the
         proposed mitigation measures in the Navy’s
         application to determine whether the resulting
         activities and mitigation measures would


  9
    The need to focus on what is practicable can be illustrated with a
simple example. Ruling out 99% of the world’s oceans from LFA sonar
use would obviously provide more protection to marine mammals. But it
would not be practicable because it would so restrict military options for
readiness training, that it would render such training ineffective.
                        NRDC V. PRITZKER                             19

         effect the least practicable adverse impact on
         marine mammals which includes a careful
         balancing of the likely degree to which the
         measure is expected to minimize adverse
         impacts to marine mammals with the likely
         effect of that measure on personnel safety,
         practicality of implementation, and impact of
         the effectiveness of the military readiness
         activity (i.e., minimizing adverse impacts to
         the lowest level practicable with mitigation
         measures).

77 Fed. Reg. at 50294.

     This formulation makes sense so far as it is stated
literally, but the problem arises that the Final Rule does not
meaningfully discuss how the mitigation measures meet that
“stringent standard.” Evans, 279 F. Supp. 2d at 1159. See
77 Fed. Reg. at 50295, 50303. Similarly, the Final Rule
states that “[o]ur responsibility under 16 U.S.C.
1371(a)(5)(A) and our implementing regulations is to
prescribe the means of effecting the least practicable adverse
impact, which involves consideration of impacts on military
readiness training and operations,” but nowhere in
rulemaking is that consideration provided. Merely reciting
the statutory language is not enough to satisfy the statute’s
explicit requirement.10 An agency acts contrary to the law
when it gives mere lip service or verbal commendation of a
standard but then fails to abide the standard in its reasoning



  10
     Defendants’ brief contends that NMFS did perform the required
analysis, but the segment of the Final Rule they cite discusses only the
“negligible impact” standard.
20                   NRDC V. PRITZKER

and decision. See Conner v. Burford, 848 F.2d 1441, 1453
(9th Cir. 1988).

    NMFS was required to analyze whether its proposed
mitigation measures reduce the effects of LFA sonar to the
“least practicable adverse impact.”               16 U.S.C.
§ 1371(a)(5)(A)(i)(I)–(II). The agency failed to do so. The
Final Rule gave only cursory attention to the requirement that
the impact to marine mammals caused by the Navy’s military
readiness activities be reduced to the least level practicable.
Then, the agency in its briefing to us conflated the least
practicable adverse impact standard with the separate
obligation that the Final Rule have a negligible impact on
marine mammal species and stock. NMFS should have
considered whether additional mitigation measures were
necessary to achieve the least practicable adverse impact on
marine mammals, and also whether these mitigation measures
would be practicable in light of the Navy’s need for effective
military readiness training.

                              V

    Reviewing the evidence before the agency, we conclude
that the “least practicable adverse impact” standard for
mitigation measures was not satisfied. The facts before
NMFS do not support its unexplained conclusion that the
Final Rule’s mitigation measures achieve the “least
practicable adverse impact” on marine mammal species,
stock, and habitat. 16 U.S.C. § 1371(a)(5)(A)(i)(II)(aa).

    We consider the practical impacts of mitigation measures
adopted by NMFS and the likely practical impact of
mitigation measures that were not adopted. Plaintiffs, while
acknowledging that the three chosen mitigation measures
                     NRDC V. PRITZKER                       21

reduce incidental take to some extent, contend that the
measures are not sufficient to effect the least practicable
adverse impact on marine mammal species, stock, and
habitat, as the MMPA requires. Plaintiffs do not challenge
the shutdown protocol and the coastal exclusion zone, two of
the three mitigation measures discussed in Part II above.
They do, however, contend that these measures taken as a
whole are inadequate to make up for deficiencies in the third
mitigation measure, the designation of OBIAs.

    The parties’ dispute over OBIA designation dates to the
beginning of the Navy’s LFA sonar program. In the two
previous iterations of LFA sonar rulemaking, many of the
same Plaintiffs in this case challenged NMFS’s OBIA
designations as underinclusive. Plaintiffs first challenged the
2002 Final Rule’s designation of only three OBIAs. Evans,
279 F. Supp. 2d at 1162. The district court concluded that
NMFS acted arbitrarily and capriciously in refusing to
designate more OBIAs despite knowing of potentially
sensitive areas, and that NMFS improperly shifted the burden
to members of the public to prove that more OBIAs were
necessary. Id. at 1163. Five years later, the 2007 Final Rule
prescribed 10 OBIAs, which Plaintiffs again challenged, and
which the district court again concluded were inadequate to
meet the MMPA’s least practicable adverse impact standard.
Nat. Res. Def. Council v. Gutierrez, No. C-07-04771 EDL,
2008 WL 360852 at *10 (N.D. Cal. Feb. 6, 2008).

    For its 2012 rulemaking, the most recent in the series,
NMFS flagged 73 candidate OBIAs by consulting prior
designated OBIAs, the World Database on Protected Areas,
the First and Second Editions of Marine Protected Areas for
Whales, Dolphins, and Porpoises by Dr. Erich Hoyt, and
senior NMFS scientists identified as “subject matter experts.”
22                   NRDC V. PRITZKER

77 Fed. Reg. at 50300. Four subject matter experts, all senior
NMFS scientists, raised concerns about OBIA selection to
NMFS’s Office of Protected Resources in a 2010 White
Paper titled Identifying Areas of Biological Importance to
Cetaceans in Data-Poor Regions. The White Paper authors
were concerned that identifying OBIAs based only on known
data would be difficult because in many instances, “relevant
cetacean data are lacking for the appropriate region or spatial
scale.” The White Paper recommended against equating
data-poor regions with “zero population density” or “no
biological importance.” Stated another way, the White Paper
cautioned that NMFS should not assume that no or minimal
data meant there were no or minimal cetacean populations in
those areas.

     The subject matter experts concluded that “proven
ecological principles” suggest a precautionary approach that
protects three types of areas as OBIAs: (1) continental shelf
waters and waters within 100 km of the continental slope;
(2) 100 km around all islands and seamounts that rise within
500 meters of the ocean surface; and (3) regions of high
primary productivity, known to correspond to higher sperm
whale presence, as explained in a 2009 monograph that the
White Paper cites. Michael A. Huston & Steve Wolverton,
The Global Distribution of Net Primary Production:
Resolving the Paradox, 79 Ecological Monographs 343
(2009). Separate from the White Paper, but consistent with
its recommendations, the Marine Mammal Commission urged
that it was “not possible” to “ensure adequate protection of
marine mammals” “if candidate areas are rejected simply
                        NRDC V. PRITZKER                             23

because of insufficient information.”11 Again, no data does
not mean no cetaceans.

    None of the subject matter experts who wrote the White
Paper was involved in drafting the Final Rule. The White
Paper appears to have played no role in the drafting of the
Final Rule until less than two months before the Final Rule
was finalized, when one of the rule drafters told the Navy that
she had “unearthed” the subject matter experts’ “guidelines
for selecting OBIAs in data-poor areas.” Even still, NMFS
only responded to the White Paper in the Final Rule
preamble’s response-to-comments section, which referred to
the White Paper’s authors as “several other commenters”
rather than as NMFS subject matter experts specifically
convened to provide their expertise to the selection process.
77 Fed. Reg. at 50303.

    NMFS’s chosen OBIA designation criteria differ
significantly from the White Paper’s recommendations. The
agency employed a multiple-step designation process that
required for designation presence of one or more of the
following attributes: high densities of animals, known
breeding/calving grounds, foraging grounds, migration routes,
or small distinct populations with limited distributions.
NMFS evaluated these criteria based on what it termed the
“best available information.” This designation method



  11
      The Marine Mammal Commission is “a federal entity possessing
expertise on issues relating to the protection of marine mammals.”
Humane Soc., 626 F.3d at 1051. The Commission is required under the
MMPA to, among other things, produce reports and recommendations on
the condition of marine mammals and the status of policies arranging for
their protection and to consult with NMFS. 16 U.S.C. § 1402.
24                   NRDC V. PRITZKER

resulted in NMFS cutting nearly 70% of the candidate
OBIAs. 77 Fed. Reg. at 50299–300.

    NMFS’s stated reason for cutting so many potential
OBIAs was that there were insufficient data proving at least
one of the chosen criteria above, even though such data do
not exist for most of the world’s oceans. NMFS also cut
some areas that its subject matter experts had nominated for
protection based on their judgment, regional expertise, or
non-peer-reviewed literature, stating that those areas
“require[d] more justification.” As the district court observed
in its review of the 2007 Final Rule’s OBIA selection, the
current list of OBIAs once again shows what the Marine
Mammal Commission deemed a “bias toward U.S. waters.”
Only one OBIA was designated in each of the Caribbean Sea,
Mediterranean Sea, Antarctic Convergence Zone, Southeast
Atlantic, northwest Pacific, and southeast Pacific, and no area
was designated on the Pacific Coast of South America. By
contrast, NMFS designated four OBIAs each in the northwest
Atlantic and the Northeast Pacific.

    Plaintiffs contend that the resulting list of 22 OBIAs was
an arbitrary and capricious policy choice. Defendants
respond that NMFS considered the White Paper’s
recommendations for data-poor regions but properly chose a
different approach, to which this court must defer. First,
Defendants contend that NMFS was under no obligation to
follow the White Paper’s guidelines, because the White Paper
itself acknowledged the existence of a policy choice between
a “precautionary” approach that “minimize[s] the chances of
overlooking biologically important areas,” or a “pure”
approach that “minimize[s] the chances of nominating sites
that are of marginal biological importance and, therefore
risk[s] overlooking biologically important areas.” Defendants
                     NRDC V. PRITZKER                        25

contend that NMFS’s resulting policy choice is entitled to
deference, in essence that NMFS’s explaining its decision not
to adopt the White Paper’s recommendations is all that the
APA requires.

    The district court agreed with Defendants. First, the
district court found that the White Paper acknowledged that
the “precautionary” approach that it advanced “risked
designating OBIAs in areas of ‘marginal biological
importance’ that did not meet NMFS’s criteria.” The district
court concluded that because the White Paper refrained from
choosing between the “precautionary” and “pure”
approaches, it was inappropriate for the district court to
substitute its judgment for that of the agency. The district
court was satisfied that “NMFS chose the pure approach and
explained its decision in the record, including reference to the
White Paper and reasons for choosing a different approach.”
Second, the district court found it probative that the White
Paper did not recommend specific OBIAs, but only provided
guidelines for inferring biological significance.

    Although review under the APA is deferential, here we
evaluate the agency’s choices in the context not just of the
APA, but also of the MMPA’s least practicable adverse
impact requirement, which sets a “stringent standard.”
Evans, 279 F. Supp. 2d at 1159. We conclude that NMFS
erred because the measures adopted do not result in the “least
practicable adverse impact” on marine mammal species,
stock, and habitat.

    OBIAs are a central component of the Final Rule’s
mitigation measures. The White Paper recommended a
“precautionary” approach toward OBIA designation. The
subject matter experts made clear that given the state of the
26                   NRDC V. PRITZKER

science, particularly the many data-poor areas of the world’s
oceans, NMFS faced a choice whether to protect areas likely
to have biological importance based on “proven ecological
principles,” or instead to “minimize the chances of
nominating sites that are of marginal biological importance
and, therefore, risk overlooking biologically important areas.”
These competing options would either risk overprotection, or
risk underprotection. NMFS chose the latter option without
evaluating whether its choice satisfied the least practicable
adverse impact standard. It should have considered whether
the precautionary approach would give more protection to
marine mammals, and then whether that protection would
impede military training to a degree making that mitigation
not practicable.

    For areas of potentially high biological importance,
NMFS’s protocol made non-designation the default, and
required specific data to overturn that conclusion. This
default is directly adverse to the subject matter experts’
recommended principle that shelf and slope areas should be
protected absent “specific data to the contrary.” NMFS
identified no science to support its conclusion that protecting
data-poor areas of potential importance as OBIAs would not
reduce adverse impacts on marine mammal species and
habitat. In fact, Defendants themselves, as well as the district
court, seem to agree with Plaintiffs that the Final Rule chose
to forego some protections that would have further reduced
the impact on marine mammals. For example, Defendants
accept that there may be alternative OBIA criteria or
mitigation measures that NMFS could have reasonably
selected, but argue that the agency’s choice should still be
given deference. Yet the MMPA requires the “least
practicable adverse impact,” and the agency has offered no
explanation why it meets that standard—in fact, as explained
                        NRDC V. PRITZKER                             27

above, it instead argues that it does not have to meet that
standard.

    Nor did NMFS consider more protected areas only to
conclude that more protection was not practicable. Although
Defendants argue that national security would be threatened
without the long-range detection capacity that LFA sonar
provides, NMFS’s decision to cut the list of potential OBIAs
did not rely on practical considerations that particular
additional OBIAs would impede military readiness training,
aside from one decision regarding the Southern California
Bight, which Plaintiffs did not challenge. Otherwise, military
practicability played no role in NMFS’s decision; in fact,
NMFS deemed it “immaterial.” Similarly, although counsel
for Defendants claimed at oral argument that the Final Rule
intended to balance the equities between military readiness
and conservation, we hold that such balancing must be made
explicit in rulemaking.12

    We owe “[o]ur highest deference” to the agency’s
“technical analyses and judgments within its area of
expertise.” League of Wilderness Defs. Blue Mountains
Biodiversity Proj. v. Allen, 615 F.3d 1122, 1131 (9th Cir.
2010). But we do not “rubber-stamp . . . administrative
decisions that [we] deem inconsistent with a statutory
mandate or that frustrate the congressional policy underlying
a statute.” Ocean Advocates v. U.S. Army Corps of

   12
       In rulemaking, it is not enough to assert without meaningful
discussion that more protective mitigation measures are impracticable.
See Conservation Council for Haw. v. Nat’l Marine Fisheries Serv., 97 F.
Supp. 3d 1210, 1230 (D. Haw. 2015) (ruling that to meet the least
practicable adverse impact standard, “something more than a refusal to
consider mitigation measures and an unexplained assertion that further
mitigation is not practical is needed”).
28                  NRDC V. PRITZKER

Engineers, 402 F.3d 846, 859 (9th Cir. 2005) (alterations in
original) (citation omitted). The agency decision here
conflicts with the statutory mandate requiring mitigation at
levels that yield the least practicable adverse impact. An
agency conclusion that is in “direct conflict with the
conclusion of its own experts,”—here, the agency’s drastic
reduction of OBIAs by eliminating candidate OBIAs in data-
poor waters against the recommendations of its subject matter
experts—is arbitrary and capricious. W. Watersheds Proj. v.
Kraayenbrink, 632 F.3d 472, 492 (9th Cir. 2011).

    Defendants also urge us to defer to the agency’s chosen
OBIA selection criteria, which differed from the White
Paper’s, on the ground that we should not second-guess an
agency’s reasonable treatment of scientific data. Defendants
rely on this court’s decision in San Luis & Delta-Mendota
Water Authority v. Jewell, 747 F.3d 581 (9th Cir. 2014), in
which we stated that we will “reject an agency’s choice of a
scientific model ‘only when the model bears no rational
relationship to the characteristics of the data to which it is
applied.’” Id. at 621 (first quoting Nat’l Wildlife Fed’n v.
EPA, 286 F.3d 554, 565 (D.C. Cir. 2002); then quoting
Appalachian Power Co. v. EPA, 135 F.3d 791, 802 (D.C. Cir.
1998)). In San Luis, experts differed on which of two
methods was best suited to assess the effect of certain water
projects on the endangered delta smelt. Id. The U.S. Fish
and Wildlife Service (FWS) chose the more conservative
method, and the court found that the choice was supported by
the record and within FWS’s discretion. Id. at 610. But here,
NMFS did not choose between competing methods designed
to answer the same question; it made a policy choice not to
protect areas—composing most of the world’s oceans—for
which little scientific data exist.
                       NRDC V. PRITZKER                             29

     This policy choice is underprotective compared to the
alternative proposed by the agency’s subject matter experts.
Although NMFS considered the White Paper’s discussion of
data-poor regions, the record does not show that NMFS
critiqued the White Paper’s scientific analysis or concluded
that its proposed guidelines were unsound.13 NMFS instead
offered two reasons for refusing to designate additional
OBIAs based on the White Paper’s principles.

    First, NMFS said that areas identified using the White
Paper’s ecological principles did “not meet the criteria we
established” for designating such areas. 77 Fed. Reg. at
50303–04. But this distinction is tautological. The White
Paper’s criteria were different than those NMFS ultimately
chose, but the difference itself does not explain why NMFS’s
criteria were equally or more capable of meeting the statutory
standard, particularly in areas where site-specific data do not
exist.

    Defendants contend that NMFS need not consider
mitigation measures that are not supported by the best
available information because federal regulations provide that
the Final Rule and its mitigation measures are to be based on
the “best available information.” 50 C.F.R. § 216.105(c).
Moreover, Defendants contend, “[t]he determination of what
constitutes the ‘best scientific data available’ belongs to the
agency’s ‘special expertise.’” San Luis, 747 F.3d at 602 (first
quoting 50 C.F.R. § 402.14(g)(8); then quoting Balt. Gas &
Elec. Co. v. Nat. Res. Def. Council, 462 U.S. 87, 103 (1983)).
Defendants make a case that NMFS used the best available
science in deciding if a potential OBIA met its screening

  13
     NMFS said the White Paper was not “unearthed” until July 9, 2012,
less than two months before NMFS published its Final Rule on August 20.
30                   NRDC V. PRITZKER

criteria. But the screening criteria themselves required a
definitive showing of biological significance even though
NMFS’s own experts concluded that “[t]he task of identifying
OBIAs for cetaceans is particularly difficult for regions in
which data on cetacean distribution or population density are
limited or lacking entirely, which includes the majority of the
world’s oceans.”

    This selection of screening criteria, in our view, was a
policy choice, not a scientific determination. We review it
according to the standard voiced by the Supreme Court in
State Farm, and hold that NMFS “failed to consider an
important aspect of the problem,” namely the underprotection
that accompanies making conclusive data an indispensable
component of OBIA designation. 463 U.S. at 43. This
systematic underprotection of marine mammals cannot be
consistent with the requirement that mitigation measures
result in the “least practicable adverse impact” on marine
mammals.

    Second, in response to the White Paper’s conclusion that
it is “not acceptable to proceed in the decision making
process as if the ‘no data’ scenario were equivalent to . . . ‘no
biological importance,’” NMFS reasoned that OBIAs are but
one component of a “suite” of mitigation measures. 77 Fed.
Reg. at 50304. However, the other two mitigation measures,
the shutdown zone and coastal exclusion zone, apply
regardless of whether an area is considered potentially
biologically important or not. Relative to these mitigation
measures, the only heightened protection possible under the
agency’s plan is designation as an OBIA. Defendants
repeatedly emphasize that NMFS’s decision not to designate
an area as an OBIA did not mean that the agency assumed the
area was biologically unimportant. But this is exactly how
                     NRDC V. PRITZKER                         31

NMFS treated data-poor areas when it categorically barred
their designation as OBIAs.

    Furthermore, the MMPA’s mitigation requirement applies
to marine mammal “species or stock and its habitat,” and
NMFS must “pay[] particular attention to rookeries, mating
grounds, and areas of similar significance[.]” 16 U.S.C.
§ 1371(a)(5)(A)(i)(II)(aa) (emphasis added). This statutory
guidance means that protecting marine mammal habitat from
the effects of LFA sonar is of paramount importance under
the MMPA. Defendants’ reference to their “suite” of
mitigation measures does not repair the underinclusive OBIA
designation protocol, particularly in light of the subject matter
experts’ conclusion that “the other forms of mitigation [are]
considerably less effective than specifying OBIAs.” The
result is that a meaningful proportion of the world’s marine
mammal habitat is underprotected.

    Relying on the other two mitigation measures—shutdown
upon detection of a marine mammal and a coastal exclusion
zone—in all areas of the ocean not designated as OBIAs
ignores that OBIAs are one of only two mitigation measures
capable of measurably reducing Level B harassment. The
shutdown zone around LFA sonar vessels is not large enough
to protect marine mammals from Level B effects between 165
and 175 dB. As a result, unless an area is designated as an
OBIA or lies within 22 km of the coast, there is minimal
mitigation of Level B harassment. Although Defendants
emphasize that OBIAs are not the core component of the
Final Rule’s “suite” of mitigation measures, the record does
32                       NRDC V. PRITZKER

not show that the other mitigation measures achieve the least
practicable adverse impact.14

     14
       To illustrate the underprotection given by NMFS’s designation
criteria, we note elimination in the 2012 Final Rule of two OBIAs that the
district court in Gutierrez faulted NMFS for refusing to include in the
2007 Final Rule: the Papahanaumokuakea Marine National Monument
(formerly named the Northwestern Hawaiian Islands Marine National
Monument) and the Galapagos Islands off the coast of Ecuador.
Gutierrez, 2008 WL 360852 at *24. The district court here did not
analyze the exclusion of Papahanaumokuakea, other than repeating
Defendants’ determination that “[m]arine animals present in the
operational [national monument] area are more than adequately protected
by the Navy’s three-part mitigation monitoring (visual, passive acoustic,
and active acoustic), delay/shutdown protocols for LFA transmissions, and
geographic restrictions,” and that the monument “is the habitat for the
endangered Hawaiian monk seal, which is not [a low-frequency] hearing
specialist. For this reason, the area did not qualify as an [OBIA].” But the
government’s management plan for Papahanaumokuakea says that “[t]he
waters of the Monument are also home to more than 20 cetacean species,
six of them federally recognized as endangered under the ESA . . . and
“depleted” under the Marine Mammal Protection Act . . . but
comparatively little is known about the distributions and ecologies of these
whales and dolphins . . . . Recent research . . . reveals that the Monument
also hosts many more humpback whales than originally thought.”
Papahanaumokuakea Marine National Monument Management Plan,
December 2008, http://sanctuaries.noaa.gov/management/mpr/mpr-
papahanaumokuakeamp-2008.pdf. For Papahanaumokuakea, NMFS
faced the familiar choice of how to handle uncertainty, and chose
underprotection without adequately explaining the decision, or how the
least practicable adverse impact standard for mitigation was met.

     The treatment of the Galapagos Islands is also illustrative. Like the
2012 Final Rule, the previous 2007 Final Rule did not designate this area
as an OBIA. The district court in Gutierrez noted with disapproval that
according to the government’s own website, the Galapagos Islands consist
of “‘highly productive coastal waters’ that create ‘important feeding zones
for marine mammals . . . . Dolphins, orcas, and blue and humpback
whales are some of the 24 species of cetacean known to visit this refuge
for feeding and mating.’” Gutierrez, 2008 WL 360852 at *7. The district
                         NRDC V. PRITZKER                                33

                                    VI

     Defendants contend, and the district court was persuaded,
that NMFS’s plans to engage in “adaptive management” will
in time allow the Final Rule to achieve the least practicable
adverse impact standard. For example, the Final Rule allows
NMFS and the Navy to specify additional OBIAs or other
forms of mitigation in annual letters of authorization (LOAs),
based on new information. Responding to the problem of
data-poor oceanic regions, the Final Rule notes:
“Recognizing that many areas throughout the world’s oceans
currently have few data to support an OBIA designation at
this time, we and the Navy will continue to conduct literature
reviews under the adaptive management provision of this
regulation.” 77 Fed. Reg. at 50303. Moreover, “information
regarding data poor areas is likely to evolve over the five year
course of the final rule and beyond, and NMFS will consider
new information to continue identifying OBIAs for [LFA
sonar] operations.” Id. at 50304. Similarly, although the
Final Rule did not designate any OBIAs for sperm whales, it
promised to consider designating such OBIAs “through the
adaptive management process.” Id. at 50309.



court concluded that “the limited and skewed selection of OBIAs
demonstrates the arbitrariness of the decision not to designate more
OBIAs, including outside the United States.” Id. In this round of
litigation, the district court reversed course and cited with approval
NMFS’s stated reason for excluding the Galapagos Islands: “Even though
blue whales are reported to be present, there is no scientific evidence that
these whales occur in these waters in densities higher than any other
similar location. Therefore, this area was not recommended as an
[OBIA].” The district court concluded without analysis that “[o]n balance,
Defendants did not act arbitrarily or capriciously.” We disagree and hold
that Defendants arbitrarily gave insignificant weight to the district court’s
prior ruling.
34                   NRDC V. PRITZKER

    Despite these nods to the future, the Final Rule does not
require that any specific mitigation measure be taken as a
result of adaptive management activities. The mere
possibility of changing the rules to accommodate new
information does not satisfy the MMPA’s strict requirements
for mitigating the effects of incidental take. The district court
observed that “the duty to adopt in advance measures to
ensure the least practicable adverse impact cannot be met
simply by deferring to potential unknown future measures.”
See also Greater Yellowstone Coal., Inc. v. Servheen,
665 F.3d 1015, 1029 (9th Cir. 2011) (“Just as it is not enough
simply to invoke ‘scientific uncertainty’ to justify an agency
action, it is not enough to invoke ‘adaptive management’ as
an answer to scientific uncertainty.”). We agree with these
principles and conclude that “adaptive management” is not an
answer to the failure to adopt mitigation measures effecting
the least practicable adverse impact on those marine mammal
species, stocks, and habitats.

                              VII

    The 2012 Final Rule does not establish means of
“effecting the least practicable adverse impact on” marine
mammal species, stock, and habitat, as is specifically required
by the MMPA. NMFS impermissibly conflated the “least
practicable adverse impact” standard with the required
“negligible impact” finding. The statute’s text makes clear
that to authorize incidental take, NMFS must achieve the
“least practicable adverse impact” standard in addition to
finding a negligible impact. NMFS also did not give
adequate protection to areas of the world’s oceans flagged by
its own experts as biologically important, based on the
present lack of data sufficient to meet NMFS’s designation
criteria, even though NMFS’s own experts acknowledged that
                 NRDC V. PRITZKER                 35

“[f]or much of the world’s oceans, data on cetacean
distribution or density do not exist.”

    The district court’s grant of summary judgment to
Defendants is REVERSED and the matter is REMANDED
to the district court for further proceedings.
