[Federal Register Volume 82, Number 151 (Tuesday, August 8, 2017)]
[Notices]
[Pages 37060-37080]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-16668]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[Docket No. 160719634-7697-02]
RIN 0648-XE756
Listing Endangered and Threatened Wildlife and Plants; Notice of
12-Month Finding on a Petition To List the Pacific Bluefin Tuna as
Threatened or Endangered Under the Endangered Species Act
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, NMFS, announce a 12-month finding on a petition to list
the Pacific bluefin tuna (Thunnus orientalis) as a threatened or
endangered species under the Endangered Species Act (ESA) and to
designate critical habitat concurrently with the listing. We have
completed a comprehensive status review of the species in response to
the petition. Based on the best scientific and commercial data
available, including the status review report, and after taking into
account efforts being made to protect the species, we have determined
that listing of the Pacific bluefin tuna is not warranted. We conclude
that the Pacific bluefin tuna is not an endangered species throughout
all or a significant portion of its range, nor likely to become an
endangered species within the foreseeable future throughout all or a
significant portion of its range. We also announce the availability of
a status review report, prepared pursuant to the ESA, for Pacific
bluefin tuna.
DATES: This finding was made on August 8, 2017.
ADDRESSES: The documents informing the 12-month finding are available
by submitting a request to the Assistant Regional Administrator,
Protected Resources Division, West Coast Regional Office, 501 W. Ocean
Blvd., Suite 4200, Long Beach, CA 90802, Attention: Pacific Bluefin
Tuna 12-month Finding. The documents are also available electronically
at http://www.westcoast.fisheries.noaa.gov/.
FOR FURTHER INFORMATION CONTACT: Gary Rule, NMFS West Coast Region at
[email protected], (503) 230-5424; or Marta Nammack, NMFS Office of
Protected Resources at [email protected], (301) 427-8469.
SUPPLEMENTARY INFORMATION:
Background
On June 20, 2016, we received a petition from the Center for
Biological Diversity (CBD), on behalf of 13 other co-petitioners, to
list the Pacific bluefin tuna as threatened or endangered under the ESA
and to designate critical habitat concurrently with its listing. On
October 11, 2016, we published a positive 90-day finding (81 FR 70074)
announcing that the petition presented substantial scientific or
commercial information indicating that the petitioned action may be
warranted. In our 90-day finding, we also announced the initiation of a
status review of the Pacific bluefin tuna and requested information to
inform our decision on whether the species warrants listing as
threatened or endangered under the ESA.
ESA Statutory Provisions
The ESA defines ``species'' to include any subspecies of fish or
wildlife or plants, and any distinct population segment (DPS) of any
vertebrate fish or wildlife which interbreeds when mature (16 U.S.C.
1532(16)). The U.S. Fish and Wildlife Service (FWS) and NMFS have
adopted a joint policy describing what constitutes a DPS under the ESA
(61 FR 4722; February 7, 1996). The joint DPS policy identifies two
criteria for making a determination that a population is a DPS: (1) The
population must be discrete in relation to the remainder of the species
to which it belongs; and (2) the population must be significant to the
species to which it belongs.
Section 3 of the ESA defines an endangered species as any species
which is in danger of extinction throughout all or a significant
portion of its range and a threatened species as one which is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. Thus, we interpret an
``endangered species'' to be one that is presently in danger of
extinction. A ``threatened species,'' on the other hand, is not
presently in danger of extinction, but is likely to become so in the
foreseeable future (that is, at a later time). In other words, the
primary statutory difference between a threatened and endangered
species is the timing of when a species may be in danger of extinction,
either presently (endangered) or in the foreseeable future
(threatened).
We determine whether any species is endangered or threatened as a
result of any one or a combination of the following five factors: The
present or threatened destruction, modification, or curtailment of its
habitat or range; overutilization for commercial, recreational,
scientific, or educational purposes; disease or predation; the
inadequacy of existing regulatory mechanisms; or other natural or
manmade factors affecting its continued existence (ESA section
4(a)(1)(A)-(E)). Section 4(b)(1)(A) of the ESA requires us to make
listing determinations based solely on the best scientific and
commercial data available after conducting a review of the status of
the species and after taking into account efforts being made by any
State or foreign nation or political subdivision thereof to protect the
species.
The petition to list Pacific bluefin tuna identified the risk
classification made by the International Union for Conservation of
Nature (IUCN). The IUCN assessed the status of Pacific bluefin tuna and
categorized the species
[[Page 37061]]
as ``vulnerable'' in 2014, meaning that the species was considered to
be facing a high risk of extinction in the wild (Collette et al.,
2014). Species classifications under IUCN and the ESA are not
equivalent; data standards, criteria used to evaluate species, and
treatment of uncertainty are not necessarily the same. Thus, when a
petition cites such classifications, we will evaluate the source of
information that the classification is based upon in light of the ESA's
standards on extinction risk and threats discussed above.
Status Review
As part of our comprehensive status review of the Pacific bluefin
tuna, we formed a status review team (SRT) comprised of Federal
scientists from NMFS' Southwest Fisheries Science Center (SWFSC) having
scientific expertise in tuna and other highly migratory species biology
and ecology, population estimation and modeling, fisheries management,
conservation biology, and climatology. We asked the SRT to compile and
review the best available scientific and commercial information, and
then to: (1) Conduct a ``distinct population segment'' (DPS) analysis
to determine if there are any DPSs of Pacific bluefin tuna; (2)
identify whether there are any portions of the species' geographic
range that are significant in terms of the species' overall viability;
and (3) evaluate the extinction risk of the population, taking into
account both threats to the population and its biological status. While
the petitioner did not request that we list any particular DPS(s) of
the Pacific bluefin tuna, we decided to evaluate whether any
populations met the criteria of our DPS Policy, in case doing so might
result in a conservation benefit to the species. Generally, however, we
opt to consider the species' rangewide status, rather than considering
whether any DPSs might exist.
In order to complete the status review, the SRT considered a
variety of scientific information from the literature, unpublished
documents, and direct communications with researchers working on
Pacific bluefin tuna, as well as technical information submitted to
NMFS. Information that was not previously peer-reviewed was formally
reviewed by the SRT. Only the best-available science was considered
further. The SRT evaluated all factors highlighted by the petitioners
as well as additional factors that may contribute to Pacific bluefin
tuna vulnerability.
In assessing population (stock) structure and trends in abundance
and productivity, the SRT relied on the International Scientific
Committee for Tuna and Tuna-Like Species' (ISC) recently completed
peer-reviewed stock assessment (ISC 2016). The ISC was established in
1995 for the purpose of enhancing scientific research and cooperation
for conservation and rational utilization of HMS species of the North
Pacific Ocean, and to establish the scientific groundwork for the
conservation and rational utilization of the HMS species in the North
Pacific Ocean. The ISC is currently composed of scientists representing
the following seven countries: Canada, Chinese Taipei, Japan, Republic
of Korea, Mexico, People's Republic of China, and the United States.
The ISC conducts regular stock assessments to assemble fishery
statistics and biological information, estimate population parameters,
summarize stock status, and develop conservation advice. The results
are submitted to Regional Fishery Management Organizations (RFMOs), in
particular the Western and Central Pacific Fisheries Commission (WCPFC)
and the Inter-American Tropical Tuna Commission (IATTC), for review and
are used as a basis of management actions. NMFS believes the ISC stock
assessment (ISC 2016) represents best available science because: (1) It
is the only scientifically based stock assessment of Pacific bluefin
tuna; (2) it was completed by expert scientists of the ISC, including
key contributions from the United States; (3) it was peer reviewed; and
(4) we consider the input parameters to the assessment to represent the
best available data, information, and assumptions.
The SRT analyzed the status of Pacific bluefin tuna in a 3-step
progressive process. First, the SRT evaluated 25 individual threats
(covering the five factors in ESA section 4(a)(1)(A)-(E)). The SRT
evaluated how each threat affects the species and contributes to a
decline or degradation of Pacific bluefin tuna by ranking each threat
in terms of severity (1-4, with ``1'' representing the lowest
contribution, and ``4'' representing the highest contribution). The
threats were evaluated in light of the Pacific bluefin tuna's
vulnerability of and exposure to the threat, and its biological
response.
Following the initial rankings of specific threats, the SRT
identified those threats where the range of rankings across the SRT was
greater than one. For these threats, subsequent discussions ensured
that the interpretation of the threat and its time-frame were clear and
consistent across team members. For example, it was necessary to
clarify that threats were considered only as they related to existing
management measures and not historical management. After clarification,
and a final round of discussion, each team member provided a final set
of severity rankings for each specific threat.
There were three specific threats (Illegal, Unregulated, and
Unreported fishing, International Management, and sea surface
temperature rise) for which the range of severity rankings remained
greater than one after they had been discussed thoroughly. For these
threats the SRT carried out a Structured Expert Decision Making process
(SEDM) to determine the final severity rank. In this SEDM approach,
each team member was asked to apportion 100 plausibility points across
the four levels of severity. Points were totaled and mean scores were
calculated. The severity level with the highest mean was determined to
be the final ranking. As will be further detailed in the Analysis of
Threats and Extinction Risk Analysis sections of this notice, the SRT
also used SEDM in steps 2 and 3 of its analysis.
The purpose of decision structuring is to provide a rational,
thorough, and transparent decision, the basis for which is clear to
both the decision maker(s) and to other observers, and to provide a
means to capture uncertainty in the decision(s). Use of qualitative
risk analysis and structured expert opinion methods allows for a
rigorous decision-making process, the defensible use of expert opinion,
and a well-documented record of how a decision was made. These tools
also accommodate limitations in human understanding and allow for
problem solving in complex situations. Risk analysis and other
structured processes require uncertainty to be dealt with explicitly
and biases controlled for. The information used may be empirical data,
or it may come from subjective rankings or expert opinion expressed in
explicit terms. Even in cases where data are sufficient to allow a
quantitative analysis, the structuring process is important to clearly
link outcomes and decision standards, and thereby reveal the reasoning
behind the decision.
This initial evaluation of individual threats and the potential
demographic risk they pose forms the basis of understanding used during
steps 2 and 3 of the SRT's analysis.
In the second step of its analysis, the SRT used the same ranking
system to evaluate the risk of each of the five factors in ESA section
4(a)(1)(A)-(E) contributing to a decline or degradation of Pacific
bluefin tuna. This involved a consideration of the combination of all
threats that fall under each of the five
[[Page 37062]]
factors. In the final step, the SRT evaluated the overall extinction
risk for Pacific bluefin tuna over two timeframes--25 years and 100
years.
The SRT's draft status review report was subjected to independent
peer review as required by the Office of Management and Budget (OMB)
Final Information Quality Bulletin for Peer Review (M- 05-03; December
16, 2004). The draft status review report was peer reviewed by
independent specialists selected from the academic and scientific
community, with expertise in tuna and/or highly migratory species
biology, conservation, and management. The peer reviewers were asked to
evaluate the adequacy, appropriateness, and application of data used in
the status review report, including the extinction risk analysis. All
peer reviewer comments were addressed prior to dissemination and
finalization of the draft status review report and publication of this
finding.
We subsequently reviewed the status review report, its cited
references, and peer review comments, and believe the status review
report, upon which this 12-month finding is based, provides the best
available scientific and commercial information on the Pacific bluefin
tuna. Much of the information discussed below on Pacific bluefin tuna
biology, distribution, abundance, threats, and extinction risk is
attributable to the status review report. However, in making the 12-
month finding determination, we have independently applied the
statutory provisions of the ESA, including evaluation of the factors
set forth in section 4(a)(1)(A)-(E); our regulations regarding listing
determinations (50 CFR part 424); our Policy Regarding the Recognition
of Distinct Vertebrate Population Segments Under the Endangered Species
Act (DPS Policy, 61 FR 4722; February 7, 1996); and our Final Policy on
Interpretation of the Phrase ``Significant Portion of Its Range'' in
the Endangered Species Act's Definitions of ``Endangered Species'' and
``Threatened Species (SPR Policy, 79 FR 37578; July 1, 2014).
Pacific Bluefin Tuna Description, Life History, and Ecology
Taxonomy and Description of Species
Pacific bluefin tuna (Thunnus orientalis) belong to the family
Scombridae (order Perciformes). They are one of three species of
bluefin tuna; the other two are the southern bluefin tuna (Thunnus
maccoyii) and the Atlantic bluefin tuna (Thunnus thynnus). The three
species can be distinguished based on internal and external morphology
as described by Collette (1999). The three species are also distinct
genetically (Chow and Inoue 1993; Chow and Kishino 1995) and have
limited overlap in their geographic ranges.
Pacific bluefin tuna are large predators reaching nearly 3 meters
(m) in length and 500 kilograms (kg) in weight (ISC 2016). They are
pelagic species known to form large schools. As with all tunas and
mackerels, Pacific bluefin tuna are fusiform in shape and possess
numerous adaptations to facilitate efficient swimming. These include
depressions in the body that accommodate the retraction of fins to
reduce drag and a lunate tail that is among the most efficient tail
shapes for generating thrust in sustained swimming (Bernal et al.,
2001).
One of the most unique aspects of Pacific bluefin tuna biology is
their ability to maintain a body temperature that is above ambient
temperature (endothermy). While some other tunas and billfishes are
also endothermic, these adaptations are highly advanced in the bluefin
tunas (Carey et al., 1971; Graham and Dickson 2001) that can elevate
the temperature of their viscera, locomotor muscle and cranial region.
The elevation of their body temperature enables a more efficient energy
usage and allows for the exploitation of a broader habitat range than
would be available otherwise (Bernal, et al., 2001).
Range, Habitat Use, and Migration
The Pacific bluefin tuna is a highly migratory species that is
primarily distributed in sub-tropical and temperate latitudes of the
North Pacific Ocean (NPO) between 20[deg] N. and 50[deg] N., but is
occasionally found in tropical waters and in the southern hemisphere,
in waters around New Zealand (Bayliff 1994).
As members of a pelagic species, Pacific bluefin tuna use a range
of habitats including open-water, coastal seas, and seamounts. Pacific
bluefin tuna occur from the surface to depths of at least 550 m,
although they spend most of their time in the upper 120 m of the water
column (Kitagawa, et al., 2000; 2004; 2007; Boustany et al. 2010). As
with many other pelagic species, Pacific bluefin tuna are often found
along frontal zones where forage fish tend to be concentrated
(Kitagawa, et al., 2009). Off the west coast of the United States,
Pacific bluefin tuna are often more tightly clustered near areas of
high productivity and more dispersed in areas of low productivity
(Boustany, et al., 2010).
Pacific bluefin tuna exhibit large inter-annual variations in
movement (e.g., numbers of migrants, timing of migration and migration
routes); however, general patterns of migration have been established
using catch data and tagging study results (Bayliff 1994; Boustany et
al., 2010; Block et al., 2011; Whitlock et al., 2015). Pacific bluefin
tuna begin their lives in the western Pacific Ocean (WPO). Generally,
age 0-1 fish migrate north along the Japanese and Korean coasts in the
summer and south in the winter (Inagake et al., 2001; Itoh et al.,
2003; Yoon et al., 2012). Depending on ocean conditions, an unknown
portion of young individuals (1-3 years old) from the WPO migrate
eastward across the NPO, spending several years as juveniles in the
eastern Pacific Ocean (EPO) before returning to the WPO (Bayliff 1994;
Inagake et al., 2001; Perle 2011). Their migration rates have not been
quantified and it is unknown what proportion of the population migrates
to the EPO and what factors contribute to the high degree of
variability across years.
While in the EPO, the juveniles make north-south migrations along
the west coast of North America (Kitagawa et al., 2007; Boustany et
al., 2010; Perle, 2011). Pacific bluefin tuna tagged in the California
Current span approximately 10[deg] of latitude between Monterey Bay
(36[deg] N.) and northern Baja California (26[deg] N.) (Boustany et
al., 2010; Block et al., 2011; Whitlock et al., 2015), although some
individuals have been recorded as far north as Washington. This
migration loosely follows the seasonal cycle of sea surface
temperature, such that Pacific bluefin tuna move northward as
temperatures warm in late summer to fall (Block et al., 2011). These
movements also follow shifts in local peaks in primary productivity (as
measured by surface chlorophyll) (Boustany et al., 2010; Block et al.,
2011). In the spring, Pacific bluefin tuna are concentrated off the
southern coast of Baja California; in summer, Pacific bluefin tuna move
northwest into the Southern California Bight; by fall, they are largely
distributed between northern Baja California and northern California.
In winter, Pacific bluefin tuna are generally more dispersed, with some
individuals remaining near the coast, and some moving farther offshore
(Boustany et al., 2010).
After spending up to 5 years in the EPO, individuals return to the
WPO where the only two spawning grounds (a southern area near the
Philippines and Ryukyu Islands, and a northern area in the Sea of
Japan) have been documented. No spawning activity, eggs, or larvae have
been observed in the EPO. The timing of spawning and
[[Page 37063]]
the particular spawning ground used after their return to the WPO has
not been established. Mature adults in the WPO generally migrate
northwards to feeding grounds after spawning, although a small
proportion of fish may move southward or eastward (Itoh 2006). Some of
the mature individuals that migrate south are taken in New Zealand
fisheries (Bayliff 1994, Smith et al., 2001), but the migration pathway
of these individuals is unknown. It is also not known how long they may
remain in the South Pacific.
Reproduction and Growth
Like most pelagic fish, Pacific bluefin tuna are broadcast spawners
and spawn more than once in their lifetime, and they spawn multiple
times in a single spawning season (Okochi, et al., 2016). They are
highly fecund, and the number of eggs they release during each spawning
event is positively and linearly correlated with fish length and weight
(Okochi et al., 2016; Ashida et al., 2015). Estimates of fecundity for
female tuna from the southern spawning area (Philippines and Ryukyu
Islands) indicate that individual fish can produce from 5 to 35 million
eggs per spawning event (Ashida et al., 2015; Shimose et al., 2016;
Chen et al., 2006). Females in the northern spawning ground (Sea of
Japan) produce 780,000-13.89 million eggs per spawning event in fish
116-170 cm fork length (FL) (Okochi, et al., 2016).
Histological studies have shown that approximately 80 percent of
the individuals found in the Sea of Japan from June to August are
reproductively mature (Tanaka, et al., 2006, Okochi et al., 2016). This
percentage does not necessarily represent the whole population as fish
outside the Sea of Japan were not examined.
Spawning in Pacific bluefin tuna occurs in only comparatively warm
waters, so larvae are found within a relatively narrow sea surface
temperature (SST) range (23.5-29.5 [deg]C) compared to juveniles and
adults (Kimura et al., 2010; Tanaka & Suzuki 2016). Larvae are thought
to be transported primarily by the northward flowing Kuroshio Current
and are largely found off coastal Japan, both in the Pacific Ocean and
Sea of Japan (Kimura et al., 2010).
As discussed above, spawning in Pacific bluefin tuna has been
recorded only in two locations: Near the Philippines and Ryukyu
Islands, and in the Sea of Japan (Okochi et al., 2016; Shimose & Farley
2016). These two spawning grounds differ in both timing and the size
composition of individuals. Near the Philippines and Ryukyu Islands,
spawning occurs from April to July and fish are from 6-25 years of age,
though most are older than 9 years of age. In the Sea of Japan,
spawning occurs later (June to August) and fish are 3-26 years old.
Pacific bluefin tuna exhibit rapid growth, reaching 58 cm or more
in length by age 1 and frequently more than 1 m in length by age 3
(Shimose et al., 2009; Shimose and Ishihara 2015). The species tends to
reach its maximum length of around 2.3 m at age 15 (Shimose et al.,
2009; Shimose and Ishihara 2015). The oldest Pacific bluefin tuna
recorded was 26 years old and measured nearly 2.5 m in length (Shimose
et al., 2009).
Feeding habits
Pacific bluefin tuna are opportunistic feeders. Small individuals
(age 0) feed on small squid and zooplankton (Shimose et al., 2013).
Larger individuals (age 1+) have a diverse forage base that is
temporally variable and, in both the EPO and WPO, they feed on a
variety of fishes, cephalopods, and crustaceans (Pinkas et al., 1971;
Shimose et al., 2013; Madigan et al., 2016; O. Snodgrass, NMFS SWFSC,
unpublished data). Diet data indicate they forage in surface waters, on
mesopelagic prey and even on benthic prey. The SWFSC conducted stomach
content analysis of age 1-5 Pacific bluefin tuna caught off the coast
of California from 2008 to 2016 and found that Pacific bluefin tuna are
generalists altering their feeding habits depending on localized prey
abundance (O. Snodgrass, NMFS SWFSC, unpublished data).
Species Finding
Based on the best available scientific and commercial information
summarized above, we find that the Pacific bluefin tuna is currently
considered a taxonomically-distinct species and, therefore, meets the
definition of ``species'' pursuant to section 3 of the ESA. Below, we
evaluate whether the species warrants listing as endangered or
threatened under the ESA throughout all or a significant portion of its
range.
Distinct Population Segment Determination
While we were not petitioned to list a distinct population segment
(DPS) of the Pacific bluefin tuna and are therefore not required to
identify DPSs, we decided, in this case, to evaluate whether any
populations of the species meet the DPS Policy criteria. As described
above, the ESA's definition of ``species'' includes ``any subspecies of
fish or wildlife or plants, and any distinct population segment of any
species of vertebrate fish or wildlife which interbreeds when mature.''
The DPS Policy requires the consideration of two elements: (1) The
discreteness of the population segment in relation to the remainder of
the species to which it belongs; and (2) the significance of the
population segment to the species to which it belongs.
A population segment of a vertebrate species may be considered
discrete if it satisfies either one of the following conditions: (1) It
is markedly separated from other populations of the same taxon as a
consequence of physical, physiological, ecological, or behavioral
factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation; or (2) it is
delimited by international governmental boundaries within which
differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the ESA. If a population
segment is found to be discrete under one or both of the above
conditions, its biological and ecological significance to the taxon to
which it belongs is evaluated. Factors that can be considered in
evaluating significance may include, but are not limited to: (1)
Persistence of the discrete population segment in an ecological setting
unusual or unique for the taxon; (2) evidence that the loss of the
discrete population segment would result in a significant gap in the
range of a taxon; (3) evidence that the discrete population segment
represents the only surviving natural occurrence of a taxon that may be
more abundant elsewhere as an introduced population outside its
historic range; or (4) evidence that the discrete population segment
differs markedly from other populations of the species in its genetic
characteristics.
Pacific bluefin tuna are currently managed as a single stock with a
trans-Pacific range. We considered a number of factors related to
Pacific bluefin tuna movement patterns, geographic range, and life
history that relate to the discreteness criteria. Among the many
characteristics of Pacific bluefin tuna that were discussed as
contributing factors to the determination of ESA discreteness, three
were regarded as carrying the most weight in the identification of
DPSs. The strongest argument for the existence of a DPS was the spatial
specificity of Pacific bluefin tuna spawning. The strongest arguments
against the existence of a DPS included Pacific bluefin tuna migratory
behavior
[[Page 37064]]
and genetic characteristics of the Pacific bluefin tuna.
Based on the current understanding of Pacific bluefin tuna
movements, Pacific bluefin tuna use one of two areas in the WPO to
spawn. There is no evidence to suggest that these represent two
separate populations but rather that, as fish increase in size, they
shift from using the Sea of Japan to using the spawning ground near the
Ryukyu Islands (e.g., Shimose et al., 2016). The spawning areas are
also characterized by physical oceanographic conditions (e.g.,
temperature), rather than a spatially fixed feature (e.g., a seamount
or promontory). This implies that the location of the spawning grounds
may be temporally and spatially fluid, as conditions change over time.
Given these considerations, the existence of two spatially distinct
spawning grounds does not provide compelling evidence that discrete
population segments exist for Pacific bluefin tuna. In addition,
concentrations of adult Pacific bluefin tuna on the spawning grounds
are found only during spawning times and not year-round.
Catch data and conventional and electronic tagging data demonstrate
the highly migratory nature of Pacific bluefin tuna. Results support
broad mixing around the Pacific. While fish cross the Pacific from the
WPO to the EPO, results indicate that they then return to the WPO to
spawn. Furthermore, the limited genetic data currently available (Tseng
et al., 2012; Nomura et al., 2014) do not support the presence of
genetically distinct population segments within the Pacific bluefin
tuna.
Pacific Bluefin Tuna Stock Assessment
The ISC stock assessment presented population dynamics of Pacific
bluefin tuna based on catch per unit effort data from 1952-2015 using a
fully integrated age-structured model. The model included various life-
history parameters including a length/age relationship and natural
mortality estimates from tag-recapture and empirical life-history
studies. Specific details on the modelling methods can be found in the
ISC stock assessment available at http://isc.fra.go.jp/reports/stock_assessments.html.
The 2016 ISC Pacific bluefin tuna stock assessment indicated three
major trends: (1) Spawning stock biomass (SSB) fluctuated from 1952-
2014; (2) SSB declined from 1996 to 2010; and (3) the decline in SSB
has ceased since 2010 yet remains near to its historical low.
Based on the stock assessment model, the 2014 SSB was estimated to
be around 17,000 mt, which represents 143,053 individuals capable of
spawning. Relative to the theoretical, model-derived SSB had there been
no fishing (i.e., the ``unfished'' SSB; 644,466 mt), 17,000 mt
represents approximately 2.6 percent of fish in the spawning year
classes. It is important to note that unfished SSB is a theoretical
number derived from the stock assessment model and does not represent a
``true'' estimate of what the SSB would have been with no fishing. This
is because it is based on the equilibrium assumptions of the model
(e.g., no environmental or density-dependent effects) and it changes
with model structures. That is, in the absence of density-dependent
effects on the population, the estimate may overestimate the population
size that can be supported by the environment and may change with
improved input parameters. When compared to the highest SSB of 160,004
mt estimated by the model in 1959, the SSB in 2014 is 10.6 percent of
the 1952-2014 historical peak.
It is important to note that while the SSB as estimated by the ISC
stock assessment is 2.6 percent of the theoretical, model-derived,
``unfished'' SSB, this value is based on a theoretical unfished
population, and only includes fish of spawning size/age. Based on the
estimated number of individuals at each age class, the number of
individuals capable of spawning in 2014 was 143,053. However, total
population size, including non-spawning capable individuals that have
not yet reached spawning age, is estimated at 1,625,837. This yields an
8 percent ratio of spawning-capable individuals to total population.
From 1952-2014, this ratio has ranged from 28 percent in 1960 to 2.5
percent in 1984, with a mean of 8 percent. The ratio in 2014 indicates
that, relative to population size, there were more spawning-capable
fish than in some years even with a similarly low total population size
(e.g., 1982-84), and the ratio was at the average for the period 1952-
2014.
The 2016 ISC stock assessment was also used to project changes in
SSB through the year 2034. The assessment evaluated 11 scenarios in
which various management strategies were altered from the status quo
(e.g., reduction in landings of smaller vs. larger individuals) and
recruitment scenarios were variable (e.g., low to high recruitment).
None of these 11 scenarios resulted in a projected reduction in SSB
through fishing year 2034.
The stock assessment also indicates that Pacific bluefin tuna is
overfished and that overfishing is occurring. This assessment, however,
is based on the abundance of the species through 2014. As described in
the following section on existing regulatory measures, the first
Pacific bluefin tuna regulations that placed limits on harvest were
implemented in 2012 with additional regulations implemented in 2014 and
2015.
Summary of Factors Affecting Pacific Bluefin Tuna
As described above, section 4(a)(1) of the ESA and NMFS'
implementing regulations (50 CFR 424.11(c)) state that we must
determine whether a species is endangered or threatened because of any
one or a combination of the following factors: The present or
threatened destruction, modification, or curtailment of its habitat or
range; overutilization for commercial, recreational, scientific, or
educational purposes; disease or predation; inadequacy of existing
regulatory mechanisms; or other natural or manmade factors affecting
its continued existence. We evaluated whether and the extent to which
each of the foregoing factors contribute to the overall extinction risk
of Pacific bluefin tuna, with a ``significant'' contribution defined,
for purposes of this evaluation, as increasing the risk to such a
degree that the factor affects the species' demographics (i.e.,
abundance, productivity, spatial structure, diversity) either to the
point where the species is strongly influenced by stochastic or
depensatory processes or is on a trajectory toward this point.
For their extinction risk analysis, the SRT members evaluated
threats and the extinction risk over two time frames. The SRT used 25
years (~3 generations for Pacific bluefin tuna) for the short time
frame and 100 years (~13 generations) for the long time frame. The SRT
concluded that the short time frame was a realistic window to evaluate
current effects of potential threats with a good degree of reliability,
especially when considering the limits of population forecasting models
(e.g., projected population trends in stock assessment models). The SRT
also concluded that 100 years was a more realistic window through which
to evaluate the effects of a threat in the more distant future that, by
nature, may not be able to be evaluated over shorter time periods. For
example, the potential effects of climate change from external forces
are best considered on multi-decadal to centennial timescales, due to
the predominance of natural variability in determining environmental
conditions in the shorter term.
[[Page 37065]]
The following sections briefly summarize our findings and
conclusions regarding threats to the Pacific bluefin tuna and their
impact on the overall extinction risk of the species. More details can
be found in the status review report, which is incorporated here by
reference.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Water Pollution
Given their highly migratory nature, Pacific bluefin tuna may be
exposed to a variety of contaminants and pollutants. Pollutants vary in
terms of their concentrations and composition depending on location,
with higher concentrations typically occurring in coastal waters. There
are two classes of pollutants in the sea that are most prevalent and
that could pose potential risks to Pacific bluefin tuna: Persistent
Organic Pollutants (POPs) and mercury. However, the SRT also considered
Fukushima derived radiation and oil pollution as independent threats.
Persistent organic pollutants are organic compounds that are
resistant to environmental degradation and are most often derived from
pesticides, solvents, pharmaceuticals, or industrial chemicals. Common
POPs in the marine environment include the organochlorine
Dichlorodiphenyltrichloroethane (DDT) and Polychlorinated biphenyls
(PCBs). Because they are not readily broken down and enter the food-
web, POPs tend to bioaccumulate in marine organisms. In fishes, some
POPs have been shown to impair reproductive function (e.g., white
croaker; Cross et al., 1988; Hose et al., 1989).
Specific information on POPs in Pacific bluefin tuna is limited.
Ueno et al. (2002) examined the accumulation of POPs (e.g., PCBs, DDTs,
and chlordanes (CHLs)) in the livers of Pacific bluefin tuna collected
from coastal Japan. They determined, as expected, that the uptake of
these organochlorines was driven by dietary uptake rather than through
exposure to contaminated water (i.e., through the gills). This research
showed that levels of organochlorines were positively and linearly
correlated with body length. Body length normalized values for PCBs,
DDTs, and CHLs were calculated as 530-2,600 ng/g lipid weight, 660-800
ng/g lipid weight, and 87-300 ng/g lipid weight, respectively. More
recently, Chiesa et al. (2016) measured pollutants from Pacific bluefin
tuna in the Western Central Pacific Ocean and found that 100 percent of
the individuals sampled tested positive for five of the six PCBs
assayed. Three POPs (specifically, polybrominated diphenyl ethers) were
detected in 5-60 percent of fish examined. Two organochlorines were
detected in 30-80 percent of samples. Unlike the findings of Ueno et
al. (2002) from coastal Japan, no DDT or its end-products were detected
in Pacific bluefin tuna in the Western Central Pacific Ocean.
While POPs have been detected in the tissues of Pacific bluefin
tuna (see above), much higher levels have been measured in other marine
fish (e.g., pelagic sharks; Lyons et al., 2015). While there is a lack
of direct experimentation on the potential impacts of POPs on Pacific
bluefin tuna, there are currently no studies which indicate that they
exist at levels that are harmful to Pacific bluefin tuna. Based on the
findings in the status review, we conclude that POPs pose no to low
risk of contributing to a decline or degradation of the Pacific bluefin
tuna.
Mercury (Hg) enters the oceans primarily through the atmosphere-
water interface. Initial sources of Hg are both natural and
anthropogenic. One of the main sources of anthropogenic Hg is coal-
fired power-plants. Total Hg emissions to the atmosphere have been
estimated at 6,500-8,200 Mg/yr, of which 4,600-5,300 Mg/yr (50-75
percent) are from natural sources (Driscoll et al., 2013). In water,
elemental Hg is converted to methyl-Hg by bacteria. Once methylated, Hg
is easily absorbed by plankton and thus enters the marine food-web. As
with POPs, Hg bioaccumulates and concentrations increase in higher
trophic level organisms.
As a top predator, Pacific bluefin tuna can potentially accumulate
high levels of Hg. Several studies have examined Hg in Pacific bluefin
tuna and reported a wide range of concentrations that vary based on
geographic location. In the WPO, measured Hg concentrations ranged from
0.66-3.23 [mu]g/g wet mass (Hisamichi et al., 2010; Yamashita et al.,
2005), whereas in the EPO they ranged from 0.31-0.508 [mu]g/g wet mass
(Lares et al., 2012; Coman et al., 2015). The latter study demonstrated
that in the EPO individuals that had recently arrived from the WPO
contained higher Hg concentrations than those that had resided in the
EPO for 1-3 years, including wild-caught individuals being raised in
net pens. By comparison, concentrations of Hg in Atlantic bluefin tuna
have been measured at 0.25-3.15 mg/kg wet mass (Lee et al., 2016).
Notably, Lee et al. (2016) demonstrated that Hg concentrations in
Atlantic bluefin tuna declined 19 percent over an 8-year period from
the 1990s to the early 2000s, a result of reduced anthropogenic Hg
emissions in North America. Tunas are also known to accumulate high
levels of selenium (Se), which is suggested to have a detoxifying
effect on methyl-Hg compounds (reviewed in Ralston et al., 2016).
The petitioners suggest that since some bluefin products are above
1 ppm, the U.S. Food and Drug Administration's (FDA) threshold, there
is cause for concern with regard to bluefin tuna health. The FDA levels
are set at the point at which consumption is not recommended for
children and women of child bearing age and are not linked to fish
health. While methyl Hg compounds have been shown to cause
neurobiological changes in a variety of animals, there have been no
studies on tuna or tuna-like species showing detrimental effects from
methyl Hg. As with the POPs, other marine species have much higher
levels of Hg contamination (Montiero and Lopes 1990; Lyons et al.,
2015). The SRT was unanimous in the determination that Hg contamination
does not pose a direct threat to Pacific bluefin tuna.
We find that water pollution poses no risk of contributing to a
decline or degradation of the Pacific bluefin tuna. While we
acknowledge that bioaccumulation of pollutants in Pacific bluefin tuna
may result in some risk to consumers, the absence of empirical studies
showing that water pollution has direct effects on Pacific bluefin tuna
implies that water pollution is not a high risk for Pacific bluefin
tuna themselves.
Plastic Pollution
Plastics have become a major source of pollution on a global scale
and in all major marine habitats (Law 2017). In 2014, global plastic
production was estimated to be 311 million metric tons (mt) (Plast.
Eur. 2015). Plastics are the most abundant material collected as
floating marine debris or from beaches (Law et al., 2010; Law 2017) and
are known to occur on the seafloor. Impacts on the marine environment
vary with type of plastic debris. Larger plastic debris can cause
entanglement leading to injury or death, while ingestion of smaller
plastic debris has the potential to cause injury to the digestive tract
or accumulation of indigestible material in the gut. Studies have also
shown that chemical pollutants may be adsorbed into plastic debris
which would provide an additional pathway for exposure (e.g., Chua et
al., 2014). Small plastics (microplastics) have been documented as the
primary source of ingested plastic materials among fish species,
particularly opportunistic planktivores
[[Page 37066]]
(e.g., Rochman et al., 2013; 2014; Matsson et al., 2015). Few studies
have examined microplastic ingestion by larger predatory fishes such as
Pacific bluefin tuna and results from these studies are mixed.
Cannon et al. (2016) found no evidence of plastics in the digestive
tracts of skipjack tuna (Katsuwonis pelamis) and blue mackerel (Scomber
australensis) in Tasmania. Choy and Drazen (2013) found no evidence of
plastic ingestion in K. pelamis and yellowfin tuna (Thunnus albacares)
in Hawaiian waters, but found that approximately 33 percent of bigeye
tuna (Thunnus obesus) had anthropogenic plastic debris in their
stomachs. While no specific studies on plastic ingestion in Pacific
bluefin tuna are available, a study of foraging ecology in the EPO
found no plastic in over 500 stomachs examined from 2008-2016 (O.
Snodgrass, NMFS, unpublished data).
We find that plastic ingestion by Pacific bluefin tuna poses no to
low risk of contributing to a decline or degradation of the Pacific
bluefin tuna. This was based in large part upon the absence of
empirical evidence of large amounts of macro- and micro-plastic
directly impacting individual Pacific bluefin tuna health.
Oil and Gas Development
There are numerous examples of oil and gas exploration and
operations posing a threat to marine organisms and habitats. Threats
include seismic activities during exploration and construction and
events such as oil spills or uncontrolled natural gas escape where
released chemicals can have severe and immediate effects on wildlife.
Unfortunately, there is limited information on the direct impacts
of oil and gas exploration and operation on pelagic fishes such as
Pacific bluefin tuna. Studies looking at the impacts of seismic
exploration on fish have mixed results. Wardle et al. (2001) and Popper
et al. (2005) documented low to moderate impacts on behavior or
hearing, whereas McCauley et al. (2003) reported long-term hearing loss
from air-gun exposure. Risk associated with seismic exploration would
likely be less of a concern for highly migratory species that can move
away and do not use sounds to communicate. Reduced catch rates in areas
for a period of time after air guns have been used are considered
evidence for this avoidance behavior in a range of species (Popper and
Hastings 2009).
The effects of seismic exploration on larval Pacific bluefin tuna,
however, could be greater than on older individuals due in part to the
reduced capacity of larvae to move away from affected areas. Davies et
al. (1989) stated that fish eggs and larvae can be killed at sound
levels of 226-234 decibel (dB), which are typically found at 0.6-3.0 m
from an air gun such as those used during seismic exploration. Visual
damage to larvae can occur at 216 dB, levels found approximately 5 m
from the air gun. Less obvious impacts such as disruptions to
developing organs are harder to gauge and are little explored in the
scientific literature; however, severe physical damage or mortality
appears to be limited to larvae within a few meters of an air gun
discharge (Dalen et al., 1987; Patin & Cascio 1999).
The most relevant study, for the purposes of the SRT, is an
evaluation of the impacts of oil pollution on the larval stage of
Atlantic bluefin tuna. Oil released from the 2010 Deepwater Horizon oil
spill in the Gulf of Mexico covered approximately 10 percent of the
spawning habitat, prompting concerns about larval survival (Muhling et
al., 2012). Modeled western Atlantic bluefin tuna recruitment for 2010
was low compared to historical values, but it is not yet clear whether
this was primarily due to oil-induced mortality, or unfavorable
oceanographic conditions (Domingues et al., 2016). Results from
laboratory studies showed that exposure to oil resulted in significant
defects in heart development in larval Atlantic bluefin tuna (Incardona
et al., 2014) with a likely reduction in fitness. A similar response
would be expected in Pacific bluefin tuna. Consequently, an oil spill
in or around the spawning grounds has the potential to impact larval
survival of Pacific bluefin tuna. Previous spills near the spawning
grounds have mostly been from ships (e.g., Varlamov et al., 1999; Chiau
2005), and have resulted in much smaller, more coastally confined
releases into the marine environment than from the Deepwater Horizon
incident. However, offshore oil exploration has increased in the region
in recent years, potentially increasing the risks of a large-scale
spill. Despite these considerations, the overall risks to Pacific
bluefin tuna associated with an oil spill were considered to be low for
a number of reasons: (1) Large oil spills are rare events; (2) Pacific
bluefin tuna larvae are spread over two spawning grounds with little
oceanographic connectivity between them, reducing risk to the
population as a whole; and (3) the population is broadly dispersed
overall.
Oil and gas infrastructure may have beneficial impacts on the
marine environment by providing habitat for a range of species and de
facto no fishing zones. California has been a prime area of research
into the effects of decommissioned oil platforms. Claisse et al. (2014)
showed that offshore oil platforms have the highest measured fish
production of any habitat in the world, exceeding even coral reefs and
estuaries. Caselle et al. (2002) showed that even remnant oil field
debris (e.g., defunct pipe lines, piers, and associated structures)
harbored diverse fish communities. This pattern is not unique to
California. For example, Fabi et al. (2004) showed that fish diversity
and richness increased within the first year after installation of two
gas platforms in the Adriatic Sea, and that biomass of fishes on these
platforms was substantial. Consequently, oil platforms may provide
forage and refuge for Pacific bluefin tuna.
In summary, we consider oil and gas development to pose no to low
risk of contributing to a decline or degradation of the Pacific bluefin
tuna.
Wind Energy Development
Concerns about climate impacts linked to the use of petroleum
products has led to an increase in renewable energy programs over the
past two decades. Offshore and coastal wind energy generating stations
have been among the fastest growing renewable energy sectors,
particularly in shallow coastal areas, which generally have consistent
wind patterns and reduced infrastructure costs due to shallow depths
and proximity to land.
Impacts of wind energy generating stations on marine fauna have
been well studied (see K[ouml]ppel, 2017 for examples). There have been
some studies predicting negative effects on marine life, particularly
birds and benthic organisms, but few empirical studies have
demonstrated direct impacts to fishes. Wilson et al. (2010) reviewed
numerous papers discussing the impacts of wind energy infrastructure
and concluded that while they are not environmentally benign, the
impacts are minor and can often be ameliorated by proper placement.
Studies on wind energy development and its impact on fishes has
largely focused on demersal species assemblages. Similar to oil and gas
platforms, wind energy platforms have been shown to have a positive
effect on demersal fish communities in that they tend to harbor high
diversity and biomass of fish populations (e.g., Wilhelmsson et al.,
2006). Following construction of ``wind farms,'' one particular concern
has been the effects of noise created by the operating mechanisms on
fish. Wahlberg and Westerberg (2005) concluded that wind
[[Page 37067]]
farm noise does not have any destructive effects on the hearing ability
of fish, even within a few meters. The major impact of the noise is
largely restricted to masking communication between fish species which
use sounds (Wahlberg and Westerberg, 2005). Given that Pacific bluefin
tuna are not known to use sounds for communication, the impact of noise
would be minimal if any. Additionally, wind farms are likely to serve
as de facto fish aggregating devices and may prove beneficial at
attracting prey and thus Pacific bluefin tuna as well. Also, given the
highly migratory nature of Pacific bluefin tuna and their broad range,
wind farms would not take up a large portion of their range and could
be avoided.
We find that wind energy development poses no to low risk of
contributing to a decline or degradation of the Pacific bluefin tuna.
This was based largely on the ability of Pacific bluefin tuna to avoid
wind farms and the absence of empirical evidence showing harm directly
to Pacific bluefin tuna.
Large-Scale Aquaculture
Operation of coastal aquaculture facilities can degrade local water
quality, mostly through uneaten fish feed and feces, leading to
nutrient pollution. The severity of these issues depends on the species
being farmed, food composition and uptake efficiency, fish density in
net pens, and the location and design of pens (Naylor et al., 2005).
There are several offshore culture facilities throughout the world,
most being within 25 kilometers (km) of shore.
The petition by CBD highlights a proposed offshore aquaculture
facility in California as a potential threat to Pacific bluefin tuna.
The proposed Rose Canyon aquaculture project would construct a facility
to raise yellowtail jack approximately 7 km from the San Diego coast.
The high capacity of the proposed project (reaching up to 5,000 mt
annually after 8 years of operation) has raised concerns about
resulting impacts to the surrounding marine environment. As the
proposed aquaculture facility would act as a point source of
pollutants, the potential impacts to widely distributed pelagic species
such as Pacific bluefin tuna will depend on oceanographic dispersal of
these pollutants within the Southern California Bight (SCB) and
surrounding regions.
Data from current meters and Acoustic Doppler Current Profilers
(ADCPs) near Point Loma have recorded seasonally reversing, and highly
variable, alongshore flows (Hendricks 1977; Carson et al., 2010).
However, cross-shelf currents were much weaker. Similarly, Lahet and
Stramski (2010) showed that river plumes in the San Diego area
identified by satellite ocean color imagery moved variably north or
south along the coast until dispersing, but were not advected offshore.
Recent studies using high-resolution simulations of a regional oceanic
modeling system have also shown limited connectivity between the
nearshore region off San Diego and the open SCB (Dong et al., 2009;
Mitari et al., 2009). This suggests that pollutants resulting from the
proposed Rose Canyon aquaculture facility would likely be dispersed
along the southern California and northern Baja California coasts
rather than offshore. Pacific bluefin tuna are distributed throughout
much of the California Current ecosystem, and are often caught more
than 100 km from shore (Holbeck et al., 2017). Tagging studies have
also shown very broad habitat use of Pacific bluefin tuna offshore of
Baja California and California (Boustany et al., 2010). It should be
noted that any aquaculture facilities in the United States are
subjected to rigorous environmental reviews and standards prior to
being permitted.
We find that habitat degradation from large-scale aquaculture poses
no to low risk of contributing to population decline or degradation in
Pacific bluefin tuna over both time-scales largely due to the very
small proportion of their habitat which would be impacted as well as
the absence of empirical evidence showing harm directly to Pacific
bluefin tuna.
Prey Depletion
As highly migratory, fast-swimming top predators, tunas have
relatively high energy requirements (Olson and Boggs 1986; Korsmeyer
and Dewar 2001; Whitlock et al., 2013; Golet et al., 2015). They
fulfill these needs by feeding on a wide range of vertebrate and
invertebrate prey, the relative contribution of which varies by
species, region, and time period. Pacific bluefin tuna in the
California Current ecosystem have been shown to prey on forage fish
such as anchovy, as well as squid and crustaceans (Pinkas et al., 1971;
Snodgrass et al., unpublished data). As commercial fisheries also
target some of these species, substantial removals could conceivably
reduce the prey base for predators such as Pacific bluefin tuna.
Previous studies have used trophic ecosystem models to show that high
rates of fishing on forage species could adversely impact other
portions of the ecosystem, including higher-order predators (Smith et
al., 2011; Pikitch et al., 2012).
Biomass of the two main forage fish in the California Current,
sardine and anchovy, has been low in recent years (Lindegren et al.,
2013; Lluch-Cota 2013). This likely represents part of the natural
cycle of these species, which appear to undergo frequent ``boom and
bust'' cycles, even in the absence of industrial-scale fishing
(Schwartzlose et al., 1999; McClatchie et al., 2017). Pacific bluefin
tuna appear to be generalists and consequently are less impacted by
these shifts in abundance than specialists. Pinkas et al. (1971) found
that Pacific bluefin tuna diets in the late 1960s were mostly anchovy
(>80 percent), coinciding with a period of relatively high anchovy
biomass. In contrast, more recent data from the 2000s show a much
higher dominance of squid and crustaceans in Pacific bluefin tuna
diets, with high interannual variability (Snodgrass et al., unpublished
data). Neither study recorded a substantial contribution of sardine to
Pacific bluefin tuna diets, but both diet studies (Pinkas et al.,
Snodgrass et al., unpublished data) were conducted during years in
which sardine biomass was comparatively low.
This ability to switch between prey species may be one reason why
Hilborn et al. (2017) found little evidence that forage fish population
fluctuations drive biomass of higher order consumers, including tunas.
This disconnect is clear for Pacific bluefin tuna. For example, in the
1980s, Pacific bluefin tuna biomass and recruitment were both very low,
but forage fish abundances in both the California Current and Kuroshio-
Oyashio ecosystems were high (Lindegren et al., 2013; Yatsu et al.,
2014). Hilborn et al. (2017) considered that a major weakness of
previous trophic studies was a lack of consideration of this strongly
fluctuating nature of forage fish populations through time. Predators
have thus likely adapted to high variability in abundance of forage
fish and other prey species by being generalists.
However, although Pacific bluefin tuna have a broad and varied prey
base in the California Current, the physiological effects of switching
between dominant prey types are not well known. Some species are more
energy-rich than others, and may have lower metabolic costs to catch
and digest (Olson & Boggs 1986; Whitlock et al., 2013). Fluctuations in
the energy content and size spectra of a prey species may also be
important, as was found for the closely-related Atlantic bluefin tuna
(Golet et al., 2015). It is
[[Page 37068]]
therefore not yet clear how periods of strong reliance on anchovy vs.
invertebrates, for example, may impact the condition and fitness of
Pacific bluefin tuna.
We find that prey depletion poses a very low threat to Pacific
bluefin tuna over the 25-year time frame, primarily because it is clear
that they are generally adapted to natural fluctuations of forage fish
biomass through prey switching. We also find that prey depletion may
pose a low to moderate threat over the 100-year timeframe, albeit with
low certainty. This was mainly because climate change is expected to
alter ecosystem structure and function to produce potentially novel
conditions, over an evolutionarily short time period. If this results
in a less favorable prey base for Pacific bluefin tuna, in either the
California Current or other foraging areas, impacts on the population
may be more deleterious than they have been in the past.
B. Overutilization for Commercial, Recreational, Scientific or
Educational Purposes
Potential threats to the Pacific bluefin tuna from overutilization
for commercial, recreational, scientific or educational purposes also
includes illegal, unregulated and unreported fishing. Each of these
potential threats is discussed in the following sections.
Commercial Fishing
Commercial fishing for Pacific bluefin tuna has occurred in the
western Pacific since at least the late 1800s. Records from Japan
indicate that several methods were used prior to 1952 when catch
records began to be taken in earnest and included longline, pole and
line, drift net, and set net fisheries. Estimates of global landings
prior to 1952 peaked around 47,635 mt (36,217 mt in the WPO and 11,418
mt in the EPO) in 1935 (Muto et al., 2008). After 1935, landings
dropped in response to a shift in maritime activities caused by World
War II. Fishing activities expanded across the North Pacific Ocean
after the conclusion of the war, and landings increased consistently
for the next decade prior to becoming more variable (Muto et al.,
2008).
There are currently five major contributors to the Pacific bluefin
tuna fisheries: Japan, Korea, Mexico, Taiwan, and the United States.
Each operates in nearshore coastal waters in the Pacific Ocean while a
few also operate in distant offshore waters. In modern fisheries,
Pacific bluefin tuna are taken by a wide range of fishing gears (e.g.,
longline, purse seine, set net, troll, pole-and-line, drift nets, and
hand line fisheries), which target different size classes (see below).
Among these fisheries, purse seine fisheries are currently the primary
contributor to landings, with the Japanese fleet being responsible for
the majority of the catch. Much of the global purse-seine catch
supports commercial grow-out facilities where fish aged approximately
1-3 are kept in floating pens for fattening prior to sale.
Estimates of landings indicate that annual catches of Pacific
bluefin tuna by country have fluctuated dramatically from 1952-2015.
During this period reported catches from the five major contributors to
the ISC peaked at 40,144 mt in 1956 and reached a low of 8,627 mt in
1990, with an average of 21,955 mt. Japanese fisheries are responsible
for the majority of landings, followed by Mexico, the United States,
Korea and Taiwan. In 2014, the United States reported commercial
landings of 408 mt, Taiwan reported 525 mt, Korea reported 1,311 mt,
Mexico reported 4,862 mt, and Japan reported 9,573 mt. These represent
2.4 percent, 3 percent, 7.7 percent, 28.4 percent, and 56 percent of
the total landings, respectively. Landings in the southern hemisphere
are small and concentrated around New Zealand.
The commercial Japanese Pacific bluefin tuna fisheries are
comprised of both distant-water and coastal longline vessels, coastal
trolling vessels, coastal pole-and-line vessels, coastal set net
vessels, coastal hand line vessels, and purse seiners. Each fishery
targets specific age classes of Pacific bluefin tuna: Coastal trolling
and pole and line target fish less than 1 year old, coastal set net and
coastal hand-line target ages 1-5, purse seiners target ages 0-10, and
the distant-water and coastal longline vessels target ages 5-20. The
distant water longline fisheries have operated for the longest time
while the coastal longline fisheries did not begin in earnest until the
mid-1960s. Between 1952 and 2015, total annual catches by Japanese
fisheries have fluctuated between a maximum of approximately 34,000 mt
in 1956 and a minimum of approximately 6,000 mt in 2012, and they have
averaged 15,653 mt.
The Japanese troll fleet harvests small, age-0 Pacific bluefin tuna
for its commercial aquaculture grow-out facilities. From 2005-2015, the
harvest of Pacific bluefin tuna for grow-out by the troll fishery has
averaged 14 percent of Japan's total landings (approximately 8.5
percent of global landings) by weight.
Nearly all commercial Pacific bluefin tuna catches by U.S. flagged
vessels on the west coast of the United States are landed in
California. Historically, the commercial fisheries for Pacific bluefin
tuna focused their efforts on the fishing grounds off Baja California,
Mexico, until the 1980s. Following the creation of Mexico's EEZ, the
U.S. purse seine fisheries largely ceased their efforts in Mexico and
became more opportunistic (Aires-da-Silva et al., 2007). Since 1980,
commercial landings of Pacific bluefin tuna have fluctuated
dramatically, averaging 859.2 mt with two peaks in 1986 (4,731.4 mt)
and 1996 (4,687.6 mt). The low catch rates are not caused by the
absence of Pacific bluefin tuna, but rather the absence of a dedicated
fishery, low market price, and the inability to fish in the Mexican
EEZ. In 2014, commercial landings of Pacific bluefin tuna in the United
States were 408 mt, representing 2.4 percent of the total global
landings.
Mexico's harvest of Pacific bluefin tuna is dominated by its purse
seine fisheries, which dramatically increased in size following the
creation of Mexico's EEZ. While most of the purse seine fisheries
target yellowfin tuna (the dominant species in the catch) in tropical
waters, Pacific bluefin tuna are caught by purse seine near Baja
California. Since 1952, reported landings in Mexico have ranged from 1-
9,927 mt with an average of 1,766.7 mt (ISC catch database http://isc.fra.go.jp/fisheries_statistics/index.html). Since grow-out
facilities began in Mexico in 1997, the purse seine fishery for Pacific
bluefin tuna almost exclusively supports these facilities. These
facilities take in age 1-3 Pacific bluefin tuna and ``fatten'' them in
floating pens for export and represent virtually all of Mexico's
reported capture of Pacific bluefin tuna. From 2005-2015, Mexico's
harvest for its grow-out facilities has averaged 26.8 percent of the
global landings.
The Korean take of Pacific bluefin tuna is dominated by its
offshore purse seine fishery with a small contribution by the coastal
troll fisheries. The fisheries generally operate off Jeju Island with
occasional forays into the Yellow Sea (Yoon et al., 2014). The purse
seine fisheries did not fully develop until the mid-1990s, and landings
were below 500 mt prior to this. Landings gradually increased and
peaked at 2,601 mt in 2003, but have declined since then, with 676 mt
landed in 2015. Since 1952, the average reported Korean landings of
Pacific bluefin tuna has been 535 mt (data not reported from 1952-
1971).
Historically, the Taiwanese fisheries have used a wide array of
gears, but since the early 1990s the fisheries are largely comprised of
small-scale longline vessels. These vessels are targeting fish on the
spawning grounds
[[Page 37069]]
near the Ryukyu Islands. The highest reported catch was in 1990 at
3,000 mt; however, landings declined to less than 1,000 mt in 2008 and
to their lowest level of about 200 mt in 2012. Landings have since
increased and the preliminary estimate of Pacific bluefin tuna landings
in 2015 was 542 mt. Since 1952, Taiwanese landings of Pacific bluefin
tuna have averaged 658 mt.
We acknowledge the Petitioner's concern that a large proportion of
Pacific bluefin tuna caught are between 0 and 2 years of age. The
petition states that 97.6 percent of fish are caught before they have a
chance to reproduce, and argues that this is a worrisome example of
growth overfishing. The interpretation of the severity of this
statement requires acknowledging several factors that are used to
evaluate the production (amount of ``new'' fish capable of being
produced by the current stock). Importantly, the estimate of production
includes considering factors such as recruitment, growth of individuals
(thus moving from one age class to the next and potentially reaching
sexual maturity), catch, and natural mortality. Excluding all other
parameters except catch results in erroneous interpretations of the
severity of a high proportion of immature fish being landed on an
annual basis. If all year classes are taken into account, the
percentage of fish in the entire population (not just in the age 0 age
class) that are harvested before reaching maturity is closer to 82
percent. While we acknowledge that this is not an ideal harvest target,
it is a more accurate representation of the catch of immature fish.
Growth overfishing occurs when the average size of harvested
individuals is smaller than the size that would produce the maximum
yield per recruit. The effect of growth overfishing is that total yield
(i.e., population size) is less than it would be if all fish were
allowed to grow to a larger size. Reductions in yield per recruit due
to growth overfishing can be ameliorated by reducing fishing mortality
(i.e., reduced landings) and/or increasing the average size of
harvested fish, both of which have been recommended by the relevant
Regional Fisheries Management Organizations (RFMOs) and adopted for the
purse seine fisheries in the western and central Pacific Ocean.
We consider commercial fishing to pose the greatest risk to
contribute to the decline or degradation of the Pacific bluefin tuna.
Threat scores given by the BRT members for commercial fishing ranged
from moderate to high (severity score of 2 to 3 with a mean of 2.29).
While we acknowledge that past trends in commercial landings have been
the largest contributor to the decline in the Pacific bluefin tuna, we
find the population size in the terminal year of the ISC stock
assessment (2014; >1,625,000 individuals and >143,000 spawning-capable
individuals) as sufficient to prevent extinction in the foreseeable
future. This is due to the fact that the population size is large
enough to prevent small population effects (e.g., Allee effects) from
having negative consequences. We also note that none of the scenarios
evaluated in the ISC stock projections showed declining trends. This
likely indicates that the proposed reductions in landings in the ISC
stock assessment that were adopted by the relevant RFMOs and have been
implemented by participating countries are likely to prevent future
declines. Therefore, we consider commercial fishing to pose a moderate
to high risk to contribute to the degradation of Pacific bluefin tuna.
Recreational Fishing
Recreational fishing for Pacific bluefin tuna occurs to some extent
in most areas where Pacific bluefin tuna occur relatively close to
shore. The majority of recreational effort appears to be in the United
States, although this may be an artifact of a lack of record keeping
outside of the United States. From the mid-1980s onward, the majority
of U.S. Pacific bluefin tuna landings have been from recreational
fisheries. Along the west coast of the United States, the recreational
fishing fleet for highly migratory species such as Pacific bluefin tuna
is comprised of commercial passenger fishing vessels (CPFVs) and
privately owned vessels operating from ports in southern California.
The vast majority of recreational fishing vessels operate from
ports in southern California from Los Angeles south to the U.S./Mexico
border, with a large proportion operating out of San Diego. Much of the
catch actually occurs in Mexican waters. The recreational catch for
Pacific bluefin tuna is dominated by hook and line fishing with a very
small contribution from spear fishing. The landings for Pacific bluefin
tuna are highly variable. This variability is linked to changes in the
number of young fish that move from the western Pacific (Bayliff 1994),
and potentially regional oceanographic variability, and is not taken to
reflect changes in overall Pacific-wide abundance.
In addition to variability in immigration to the EPO, regulatory
measures impact the number of fish caught. As mentioned, most U.S.
fishing effort occurs in Mexican waters. In July 2014, Mexico banned
the capture of Pacific bluefin tuna in its EEZ for the remainder of the
year, reducing the catch by the U.S. recreational fleet. In 2015, while
this ban was lifted, the United States instituted a two fish per angler
per day bag limit and a 6 fish per multi-day fishing trip bag limit on
Pacific bluefin tuna, lowered from 10 fish per angler per day and 30
fish total for multi-day trips (80 FR 44887; July 28, 2015). It is
difficult to quantify the effects of the reduced bag limit at the
current time as there are only two years of landings data following the
reduction (2015-16). This is further complicated by an absence of an
index of availability of Pacific bluefin tuna to the recreational
fishery. Anecdotal evidence in the form of informal crew and fisher
interviews suggests that Pacific bluefin tuna have been in high
abundance since 2012. CPFV landings in 2014-16 declined following an
exceptionally productive year in 2013. Whether this was an effect of
the reduced bag limit or an artifact of Pacific bluefin tuna
availability is uncertain. While the petition raises the concern that
the two fish per day per angler bag limit is insufficient as the
fishery is ``open access'' (an angler may fish as many days as they
wish), it is important to note that the number of anglers participating
in CPFV trips has not increased dramatically since the late 1990s. It
should also be noted that the average number of Pacific bluefin tuna
caught per angler on an annual basis has never exceeded 1.4 (2013),
thus the two fish per day per angler bag limit will effectively prevent
a major expansion of the Pacific bluefin tuna recreational landings.
Since 1980, the peak of the U.S. recreational fishery was in 2013
when 63,702 individual fish were reported in CPFV log books, with an
estimated weight of 809 tons. This was more than the total U.S.
commercial catch in 2013 (10.1 mt), keeping in mind that commercial
vessels cannot go into Mexican waters. The average recreational catch
is far lower (264 mt average from 2006-2015). The peak recreational
CPFV landings in the United States in 2013 represented 7 percent of the
total global catch of Pacific bluefin tuna in that same year, whereas
in 2015 it represented 3.2 percent of total global catch.
Private vessel landings are more difficult to quantify as they rely
on voluntary interviews with fishers at only a few of the many landing
ports. In 2015, the estimated landings by private vessels was 6,195
individual Pacific bluefin tuna, which represented approximately 30
percent of all U.S.
[[Page 37070]]
recreational landings. Note, that these values are not included in the
estimates above and represent additional landings.
At 3.2 percent of the total global landings, we consider the U.S.
recreational fishery to be a minor overall contributor to the global
catch of Pacific bluefin tuna, and recent measures have been
implemented to reduce landings. Given that recreational landings have
been reduced through increased management, we consider recreational
fishing as posing no or a low risk of contributing to population
decline or degradation in Pacific bluefin tuna.
Illegal, Unreported, or Unregulated Fishing
Illegal, Unreported or Unregulated (IUU) fishing, as defined in 50
CFR 300.201, means:
(1) In the case of parties to an international fishery management
agreement to which the United States is a party, fishing activities
that violate conservation and management measures required under an
international fishery management agreement to which the United States
is a party, including but not limited to catch limits or quotas,
capacity restrictions, bycatch reduction requirements, shark
conservation measures, and data reporting;
(2) In the case of non-parties to an international fishery
management agreement to which the United States is a party, fishing
activities that would undermine the conservation of the resources
managed under that agreement;
(3) Overfishing of fish stocks shared by the United States, for
which there are no applicable international conservation or management
measures, or in areas with no applicable international fishery
management organization or agreement, that has adverse impacts on such
stocks;
(4) Fishing activity that has a significant adverse impact on
seamounts, hydrothermal vents, cold water corals and other vulnerable
marine ecosystems located beyond any national jurisdiction, for which
there are no applicable conservation or management measures or in areas
with no applicable international fishery management organization or
agreement; or
(5) Fishing activities by foreign flagged vessels in U.S. waters
without authorization of the United States.
While there is likely some level of IUU fishing for Pacific bluefin
tuna in the Pacific, no reports of substantial IUU fishing have
emerged, thus the amount cannot be determined. However, improvements to
catch document schemes in several countries have been proposed/
implemented in an effort to combat IUU harvest, and the most recent
advice from the relevant RFMOs requires improvements to reporting. The
SRT members had a range of opinions on the effects of IUU fishing on
population decline or degradation for Pacific bluefin tuna, ranging
from no impact to moderate impact. The SRT therefore performed a SEDM
analysis to arrive at the conclusion that the magnitude of potential
IUU fishing losses for Pacific bluefin tuna were likely low relative to
existing commercial catches and thus not likely to increase
substantially in the future; however, the certainty around this
determination is low.
Given the absence of estimates of IUU fishing losses for Pacific
bluefin tuna, we have a low level of certainty for this threat.
However, with the continued improvements in catch documentation and the
assumption of low IUU take relative to the commercial harvest, we
determined that IUU fishing represented a low to moderate risk of
contributing to population decline or degradation in Pacific bluefin
tuna.
Scientific and Educational Use
Pacific bluefin tuna are used in scientific research for a range of
studies such as migration patterns, stable isotope analysis, and
feeding preference. The amount of lethal use of Pacific bluefin tuna in
scientific and educational pursuits is negligible, as most tissues used
in research (e.g. otoliths, muscle samples) are sourced from fish
already landed by fishers. We therefore find no evidence that
scientific or educational use poses a risk to contribute to the decline
or degradation of Pacific bluefin tuna.
C. Disease and Predation
Disease
Studies of disease in Pacific bluefin tuna are largely absent from
the literature. Most studies involve the identification of parasites
normally associated with cage culture. Parasites are often associated
with mortalities and reduced production among farmed marine fishes
(Hayward et al., 2007). Epizootic levels of parasites with short,
direct, one-host life cycles, such as monogeneans, can be reached very
quickly in cultured fish because of the confinement and proximity of
these fish (Thoney and Hargis 1991). Among wild marine fishes,
parasites are usually considered benign, though they can be associated
with reduced fecundity of their hosts (Jones 2005; Hayward et al.,
2007).
Munday et al. (2003) provided a summary of metazoan infections
(myxosporeans, Kudoa sp., monogeneans, blood flukes, larval cestodes,
nematodes, copepods) in tuna species. Many metazoans infect Thunnus
spp., but not many are known to cause mortalities; most studies to date
have focused on the health and/or economic importance of these
diseases. For example, postmortem liquefaction of muscle due to
myxosporean infections occurs in albacore, yellowfin tuna, and bigeye
tuna (Thunnus obesus), and in poorly identified Thunnus spp. Lesions
caused by Kudoa sp. have been found in yellowfin tuna and southern
bluefin tuna (Langdon 1990; Kent et al., 2001). Munday et al. (2003)
report that southern bluefin tuna have been found to be infected with
an unidentified, capsalid monogenean that causes respiratory stress but
does not lead to mortality.
Young Pacific bluefin tuna are often infected with red sea bream
iridoviral, but the disease never appears in Pacific bluefin tuna more
than 1 year of age, and occurrence is restricted to periods of water
temperatures greater than 24 [deg]C (Munday et al., 2003). Mortality
rates rarely reach greater than 10 percent for young fish. The fish
either die during the acute phase of the disease, or they become
emaciated and die later.
There is no evidence of transmission of parasites or other
pathogens from captive Pacific bluefin tuna in tuna ranches. This is
likely due to the fact that wild Pacific bluefin tuna are not likely to
be in close enough proximity to pens used to house Pacific bluefin
tuna.
We find that disease poses no to low risk of contributing to
population decline or degradation in Pacific bluefin tuna. This was
based largely on the absence of empirical evidence of abnormal levels
of natural disease outbreaks in Pacific bluefin tuna, the absence of
observations of wild Pacific bluefin tuna swimming in close enough
proximity to ``farms'' such that disease transmission is possible, and
the absence of empirical evidence showing disease transmission from
``farms'' to wild Pacific bluefin tuna.
Predation
As large predators, Pacific bluefin tuna are not heavily preyed
upon naturally after their first few years. Predators of adult Pacific
bluefin tuna may include marine mammals such as killer whales (Orcinus
orca) or shark species such as white (Carcharodon carcharias) and mako
sharks (Isurus spp.) (Nortarbartolo di Sciara 1987; Collette and Klein-
MacPhee 2002; de
[[Page 37071]]
Stephanis 2004; Fromentin and Powers 2005). Juvenile Pacific bluefin
tuna may be preyed upon by larger opportunistic predators and, to a
lesser degree, seabirds.
We find that natural predation poses no to low risk of contributing
to population decline or degradation in Pacific bluefin tuna. This was
based primarily on the limited diversity of predators and absence of
empirical evidence showing abnormal decline/degradation of Pacific
bluefin tuna by predation.
D. The Inadequacy of Existing Regulatory Mechanisms
The current management and regulatory schemes for Pacific bluefin
tuna are intrinsically linked to the patterns of utilization discussed
in the previous section ``Overutilization for Commercial, Recreational,
Scientific or Educational Purposes.'' The evaluation in this section
focuses on the adequacy or inadequacy of the current management and
regulatory schemes to address the threats identified in the section on
``Overutilization for Commercial, Recreational, Scientific or
Educational Purposes.''
Pacific bluefin tuna fisheries are managed under the authorities of
the Magnuson-Stevens Fishery Conservation and Management Act (MSA), the
Tuna Conventions Act of 1950 (TCA), and the Western and Central Pacific
Fisheries Convention Implementation Act (WCPFCIA). The TCA and WCPFCIA
authorize the Secretary of Commerce to implement the conservation and
management measures of the Inter-American Tropical Tuna Commission
(IATTC) and Western and Central Pacific Fisheries Commission (WCPFC),
respectively.
International Fisheries Management
Pacific bluefin tuna is managed as a single Pacific-wide stock
under two RFMOs: The IATTC and the WCPFC. Both RFMOs are responsible
for establishing conservation and management measures based on the
scientific information, such as stock status, obtained from the ISC.
The IATTC has scientific staff that, in addition to conducting
scientific studies and stock assessments, also provides science-based
management advice. After reviewing the Pacific bluefin tuna stock
assessment prepared by the ISC, the IATTC develops resolutions. Mexico
and the United States are the two IATTC member countries that currently
fish for, and have historically fished for, Pacific bluefin tuna in the
EPO. Thus, the IATTC resolutions adopted were intended to apply to
these two countries.
The WCPFC has a Northern Committee (WCPFC-NC), which consists of a
subset of the WCPFC members and cooperating non-members, that meets
annually in advance of the WCPFC meeting to discuss management of
designated ``northern stocks'' (currently North Pacific albacore,
Pacific bluefin tuna, and North Pacific swordfish). After reviewing the
stock assessments prepared by the ISC, the WCPFC-NC develops the
conservation and management measures for northern stocks and makes
recommendations to the full Commission for the adoption of measures.
Because Pacific bluefin tuna is a ``northern stock'' in the WCPFC
Convention Area, without the recommendation of the Northern Committee,
those measures would not be adopted by the WCPFC. The WCPFC's
Scientific Committee also has a role in providing advice to the WCPFC
with respect to Pacific bluefin tuna; to date its role has been largely
limited to reviewing and endorsing the stock assessments prepared by
the ISC.
The IATTC and WCPFC first adopted conservation and management
measures for Pacific bluefin tuna in 2009, and the measures have been
revised five times. The conservation and management measures include
harvest limits, size limits, and stock status monitoring plans. In
recent years, coordination among both RFMOs has improved in an effort
to harmonize conservation and management measures to rebuild the
depleted stock. The most relevant resolutions as they relate to recent
Pacific bluefin tuna management are detailed below.
In 2012, the IATTC adopted Resolution C-12-09, which set commercial
catch limits on Pacific bluefin tuna in the EPO for the first time.
This resolution limited catch by all IATTC members to 5,600 mt in 2012
and to 10,000 mt in 2012 and 2013 combined, notwithstanding an
allowance of up to 500 mt annually for any member with a historical
catch record of Pacific bluefin tuna in the eastern Pacific Ocean
(i.e., the United States and Mexico). Resolution C-13-02 applied to
2014 only and, similar to C-12-09, limited catch to 5,000 mt with an
allowance of up to 500 mt annually for the United States. Following the
advice from the IATTC scientific staff, Resolution C-14-06 further
reduced the catch limit by approximately 34 percent--6,000 mt for
Mexico and 600 mt for the United States for 2015 and 2016 combined. The
IATTC most recently adopted Resolution C-16-08. In accordance with the
recommendations of the IATTC's scientific staff, this resolution
maintains the same catch limits that were applicable to 2015 and 2016--
6,600 mt in the eastern Pacific Ocean during 2017 and 2018 combined.
The final rule implementing Resolution C-16-08 was published on April
21, 2017, and had an effective date of May 22, 2017. The most recent
regulations represent roughly a 33 percent reduction compared to the
average landings from 2010-2014 (5,142 mt). Resolution C-16-08 also
outlined next steps in developing a framework for managing the stock in
the long-term. This framework included an initial goal of rebuilding
the SSB to the median point estimate for 1952-2014 by 2024 with at
least 60 percent probability, and further specifies that the IATTC will
adopt a second rebuilding target in 2018 to be achieved by 2030. The
second Joint IATTC-WCPFC Northern Committee Working Group meeting on
Pacific bluefin tuna, that will be held August 28-September 1, 2017,
will discuss the development of a rebuilding strategy (second
rebuilding target and timeline, etc.) and long-term precautionary
management framework (e.g. management objectives, limit and target
reference points, and harvest control rules).
The conservation and management measures adopted by the WCPFC have
become increasingly restrictive since the initial 2009 measure. In
2009, total fishing effort north of 20[deg] N. was limited to the 2002-
2004 annual average level. At this time, an interim management
objective--to ensure that the current level of fishing mortality rate
was not increased in the western Pacific Ocean--was also established.
In 2010, Conservation and Management Measure (referred to as CMM) 2010-
04 established catch restrictions in addition to the effort limits
described above for 2011 and 2012. A similar measure, CMM 2012-06, was
adopted for 2013. In 2014 (CMM 2013-09) all catch of Pacific bluefin
tuna less than 30 kilograms (kg) was reduced by 15 percent below the
2002-2004 annual average. In 2015 (CMM 2014-04) the harvest of Pacific
bluefin tuna less than 30 kilograms was reduced to 50 percent of the
2002-2004 annual average. The CMM 2014-04 also limits all catches of
Pacific bluefin tuna greater than 30 kg to no more than the 2002-2004
annual average level. The measure was amended in 2015 (CMM 2015-04) to
include a requirement to adopt an ``emergency rule'' where additional
actions would be triggered if recruitment in 2016 was extremely poor.
However, this emergency rule was not
[[Page 37072]]
agreed to at the 2016 Northern Committee annual meeting. It is expected
that it will be discussed again at the Northern Committee meeting in
August 2017. Lastly, the measure was amended in 2016 (CMM 2016-04) to
allow countries to transfer some of their catch limit for Pacific
bluefin tuna less than 30 kg to their limit on fish larger than 30 kg
(i.e., increase catch of larger fish and decrease catch of smaller
fish); the reverse is not allowed. Unlike the IATTC resolutions for
Pacific bluefin tuna, the current WCPFC Pacific bluefin tuna measure
does not have an expiration date, although it may be amended or
removed. Both the IATTC and WCPFC measures require reporting to promote
compliance with the provisions of the measures.
In summary, the WCPFC adopted harvest limits for Pacific bluefin
tuna in 2010 and further reduced those limits in 2012, 2014, and 2016.
The IATTC adopted harvest limits for Pacific bluefin tuna in 2012 and
further reduced those limits in 2014 and 2016. Additionally, both RFMOs
addressed concerns about monitoring harvest by adopting monitoring and
reporting plans in 2010. Furthermore, the ISC stock assessment predicts
that under all scenarios the current harvest limits will allow for
rebuilding the abundance of Pacific bluefin tuna to targets by 2030.
After thorough discussion, the SRT members had a range of opinions
on the effects of international management on population decline or
degradation for Pacific bluefin tuna, ranging from no impact to high
impact. The SRT therefore used SEDM to arrive at the conclusion that
inadequacy of international management poses a low risk of contributing
to population decline or degradation in Pacific bluefin tuna over the
short time period (25 years) and a moderate risk over the long time
period (100 years).
Domestic Fisheries Management
Domestic fisheries are managed under the MSA. The MSA provides
regional fishery management councils with authority to prepare Fishery
Management Plans (FMPs) for the conservation and management of
fisheries in the U.S. EEZ. The MSA was reauthorized and amended in 1996
by the Sustainable Fisheries Act (SFA) and again in 2006 by the
Magnuson-Stevens Fishery Conservation and Management Reauthorization
Act (MSRA). Among other modifications, the SFA added requirements that
FMPs include measures to rebuild overfished stocks.
The Pacific Fishery Management Council (Pacific Council) has
purview over the U.S. West Coast fisheries, which catch the large
majority of Pacific bluefin tuna caught by U.S. vessels. The Pacific
Council makes recommendations on the implementation of the FMP for U.S.
West Coast Fisheries for highly migratory species (HMS FMP) for
consideration by NMFS. Additionally, the Pacific Council makes
recommendations to NMFS on issues expected to be considered by the
IATTC and WCPFC. During its November 2016 meeting, the Pacific Council,
in response to a petition that NMFS received by the Center for
Biological Diversity, recommended a review of domestic status
determination criteria for Pacific bluefin tuna at upcoming meetings in
March, June, and September 2017. The domestic status determination
criteria, also commonly referred to as reference points, are targets
for fishing effort and abundance of the population. At the March 2017
meeting, NMFS provided a report to the Pacific Council that included
domestic status determination criteria for Pacific bluefin tuna.
The Pacific Council, in response to NMFS' 2013 determination that
the Pacific bluefin tuna stock was overfished and subject to
overfishing (78 FR 41033; July 9, 2013), recommended reducing the bag
and possession limits for Pacific bluefin tuna in the recreational
fishery. The Pacific Council recommended reducing the daily bag limit
from 10 to 2 fish and the possession limit from 30 to 6 fish. Based on
analyses conducted at the SWFSC, this was projected to reduce landings
by 10.4 percent in U.S. waters and 19.4 percent in U.S. and Mexican
waters combined (Stohs, 2016). We published a final rule in 2015
implementing the bag limit of two fish per day and possession limit of
six fish per trip (80 FR 44887, July 28, 2015).
NMFS coordinates closely with the California Department of Fish and
Wildlife (CDFW) to monitor the Pacific bluefin tuna fishery. The State
of California requires that fish landed in California have a
corresponding receipt, which indicates quantity landed. Together, NMFS
and CDFW monitor landings to ensure catch limits agreed to by the IATTC
are not exceeded.
In summary, NMFS initially set limits for commercial and
recreational harvest limits in 2010 and further reduced those limits in
2012, 2014, and 2016. The CDFW monitors and reports commercial and
recreation harvest to NMFS. When U.S. commercial catch limits are met,
NMFS closes the fishery. Furthermore, the ISC stock assessment predicts
that the current harvest limits will allow for stable or increasing
Pacific bluefin tuna SSB. We expect the current harvest limits to be
effective at reducing the impact of domestic commercial and
recreational fisheries, and we will continue to monitor the
effectiveness of those regulations. We find that U.S. domestic
management of commercial and recreational fishing poses no or low risk
of contributing to population decline or degradation in Pacific bluefin
tuna.
E. Other Natural or Man-Made Factors Affecting Its Continued Existence
The other factors affecting the continued existence of Pacific
bluefin tuna that we analyzed are climate change, radiation
contamination from Fukushima, and the risks of low abundance levels
inherent in small populations.
Climate Change
Over the next several decades climate change models predict changes
to many atmospheric and oceanographic conditions. The SRT considered
these predictions in light of the best available information. The SRT
felt that there were three physical factors resulting from climate
change predictions that would have the most impact on Pacific bluefin
tuna: Rising sea surface temperatures (SST), increased ocean
acidification, and decreases in dissolved oxygen.
Rising Sea Surface Temperatures
Rising SST may affect Pacific bluefin tuna spawning and larval
development, prey availability, and trans-pacific migration habits.
Pacific bluefin tuna spawning has only been recorded in two locations:
Near the Philippines and Ryukyu Islands in spring, and in the Sea of
Japan during summer (Okochi et al., 2016; Shimose & Farley 2016).
Spawning in Pacific bluefin tuna occurs in comparatively warm waters,
and so larvae are found within a relatively narrow temperature range
(23.5-29.5 [deg]C) compared to adults (Kimura et al., 2010; Tanaka &
Suzuki 2016).
Currently, SSTs within the theoretically suitable range for larvae
are present near the Ryukyu Islands between April and June, and in the
Sea of Japan during July and August (Caiyun & Ge 2006; Seo et al.,
2014; Tanaka & Suzuki 2016). Warming of 1.5-3 [deg]C in the region may
shift suitable times to earlier in the year and/or places for spawning
northwards. Under the most pessimistic (``business as usual'')
CO2 emission and concentration scenarios, SSTs in the North
Pacific are likely to increase substantially by the end of the 21st
century (Hazen et al., 2013; Woodworth-Jefcoats et al., 2016). However,
there is considerable spatial
[[Page 37073]]
heterogeneity in these projections. The southern Pacific bluefin tuna
spawning area is projected to warm 1.5-2 [deg]C by the end of the 21st
century, with particularly weak warming in the Kuroshio Current region.
In contrast, the Sea of Japan may warm by more than 3 [deg]C compared
to recent historical conditions (Seo et al., 2014; Scott et al., 2016;
Woodworth-Jefcoats et al., 2016).
The precise mechanisms by which warming waters will affect Pacific
bluefin tuna larvae are not entirely clear. Kimura et al. (2010)
assumed that the lethal temperature for larvae was 29.5 [deg]C.
However, Muhling et al. (2010) and Tilley et al. (2016) both reported
larvae of the closely-related Atlantic bluefin tuna in the Gulf of
Mexico at SSTs of between 29.5 and 30.0 [deg]C. In addition, tropical
tuna larvae can tolerate water temperatures of well above 30 [deg]C
(Sanchez-Velasco et al., 1999; Wexler et al., 2011; Muhling et al.,
2017). Pacific bluefin tuna larvae may have fundamentally different
physiology from that of these other species, or it is possible that the
observed upper temperature limit for Pacific bluefin tuna larvae in the
field is more a product of the time and place of spawning, rather than
an upper physiological limit.
Similar to other tuna species, larval Pacific bluefin tuna appear
to have highly specialized and selective diets (Uotani et al., 1990;
Llopiz & Hobday 2015). Smaller larvae rely primarily on copepod
nauplii, before moving to cladocerans, copepods such as Farranula and
Corycaeus spp. and other zooplankton. In the Sea of Japan region, the
occurrence of potentially favorable prey organisms for larval Pacific
bluefin tuna appears to be associated with stable post-bloom conditions
during summer (Chiba & Saino, 2003). This suggests a potential
phenological match to Pacific bluefin tuna spawning. Environmentally-
driven changes in the evolution of this zooplankton community, or the
timing of spawning, could thus affect the temporal match between larvae
and their prey. Woodworth-Jefcoats et al. (2016) project a 10-20
percent decrease in overall zooplankton density in the western Pacific
Ocean, but how this may relate to larval Pacific bluefin tuna prey
availability is not yet known.
Climate change may affect the foraging habitats of Pacific bluefin
tuna. Adult and older juvenile (>1 year) Pacific bluefin tuna disperse
from the spawning grounds in the western Pacific and older juveniles
can make extensive migrations, using much of the temperate North
Pacific. An unknown proportion of 1-2 year old fish migrate to foraging
grounds in the eastern North Pacific (California Current LME) and
typically remain and forage in this region for several years (Bayliff
et al., 1991; Bayliff 1994; Rooker et al., 2001; Kitagawa et al., 2007;
Boustany et al., 2010; Block et al., 2011; Madigan et al., 2013;
Whitlock et al., 2015).
Sea surface temperatures in the California Current are expected to
increase up to 1.5-2 [deg]C by the end of the 21st century (Hazen et
al., 2013; Woodworth-Jefcoats et al., 2016). Pacific bluefin tuna
tagged in the California Current demonstrate a seasonal north-south
migration between Baja California (10[deg] N.) and near the California-
Oregon border (42[deg] N.) (Boustany et al., 2010; Block et al., 2011;
Whitlock et al., 2015), although some fish travel as far north as
Washington State. The seasonal migration follows local peaks in
productivity (as measured by surface chlorophyll), such that fish move
northward from Baja California after the local productivity peak in
late spring to summer (Boustany et al., 2010; Block et al., 2011).
Uniform warming in this region could impact Pacific bluefin tuna
distribution by moving their optimal temperature range (and thermal
tolerance) northward. However, it is unlikely that rising temperatures
will be a limiting factor for Pacific bluefin tuna, as appropriate
thermal habitat will likely remain available.
The high productivity and biodiversity of the California Current is
driven largely by seasonal coastal upwelling. Although there is
considerable uncertainty on how climate change will impact coastal
upwelling, basic principles indicate a potential for upwelling
intensification (Bakun 1990). Bakun's hypothesis suggested that the
rate of heating over land would be enhanced relative to that over the
ocean, resulting in a stronger cross-shore pressure gradient and a
proportional increase in alongshore winds and resultant upwelling
(Bakun et al., 2015; Bograd et al., 2017). A recent publication
(Sydeman et al., 2014) described a meta-analysis of historical studies
on the Bakun hypothesis and found general support for upwelling
intensification, but with significant spatial (latitudinal) and
temporal (intraseasonal) variability between and within the eastern
boundary current systems. In the California Current, a majority of
analyses indicated increased upwelling intensity during the summer
(peak) months, though this signal was most pronounced in the northern
California Current (Sydeman et al., 2014).
To date, global climate models have generally been too coarse to
adequately resolve coastal upwelling processes (Stock et al., 2010),
although recent studies analyzing ensemble model output have found
general support for projected increases in coastal upwelling in the
northern portions of the eastern boundary current systems (Wang et al.,
2015; Rykaczewski et al., 2015). Using an ensemble of more than 20
global climate models from the IPPC's Fifth Assessment Report,
Rykaczewski et al. (2015) found evidence of a small projected increase
in upwelling intensity in the California Current north of 40[deg] N.
latitude and a decrease in upwelling intensity to the south of this
range by the end of the 21st century under RCP 8.5. Pacific bluefin
tuna are more commonly found to the south of the 40[deg] N. latitude
mark. Perhaps more importantly, Rykaczewski et al. (2015) described
projected changes in the phenology of coastal upwelling, with an
earlier transition to positive upwelling within the peak upwelling
domain. Overall, these results suggest a poleward displacement of peak
upwelling and potential lengthening of the upwelling season in the
California Current, even if upwelling intensity may decrease. The
phenological changes in coastal upwelling may be most important, as
these may lead to spatial and temporal mismatches between Pacific
bluefin tuna and their preferred prey (Cushing 1990; Edwards and
Richardson 2004; Bakun et al., 2015). However, the bluefin tuna's
highly migratory nature and plasticity in migratory patterns may help
to mitigate shifts in phenology.
The information directly relating to food web alterations that may
impact Pacific bluefin tuna is scarce. While changes to upwelling
dynamics in foraging areas have been examined, it is still relatively
speculative, and literature on the potential impacts of the projected
changes is limited. Given their trophic position as an apex predator,
and the fact that Pacific bluefin tuna are opportunistic feeders that
can change their preferred diet from year to year, alterations to the
food web may have less impact on Pacific bluefin tuna than on other
organisms that are reliant on specific food sources.
Climate change may affect the Pacific bluefin tuna's migratory
pathways. Pacific bluefin tuna undergo trans-Pacific migrations, in
both directions, between the western Pacific spawning grounds and
eastern Pacific foraging grounds (Boustany et al., 2010; Block et al.,
2011). For both migrations, Pacific bluefin tuna remain within a
relatively narrow latitudinal band (30-40[deg] N.) within the North
Pacific Transition Zone (NPTZ), which is characterized by generally
temperate conditions. This
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region, marking the boundary between the oligotrophic subtropical and
more productive subarctic gyres, is demarcated by the seasonally-
migrating Transition Zone Chlorophyll Front (TZCF; Polovina et al.,
2001; Bograd et al., 2004). Climate-driven changes in the position of
the TZCF, and in the thermal environment and productivity within this
region, could impact the migratory phase of the Pacific bluefin tuna
life cycle.
Under RCP 8.5, SSTs in the NPTZ are expected to increase by 2-3
[deg]C by the end of the 21st century (Woodworth-Jefcoats et al.,
2016), with the highest increases on the western side. The increased
temperatures within the NPTZ are part of the broader projected changes
in the central North Pacific Ocean, including an expansion of the
oligotrophic Subtropical Gyre, a northward displacement of the
transition zone, and an overall decline in productivity (Polovina et
al., 2011). The impacts of these changes on species that make extensive
use of the NPTZ could be substantial, resulting in a gain or loss of
core habitat, distributional shifts, and regional changes in
biodiversity (Hazen et al., 2013). Using habitat models based on a
multi-species biologging dataset, and a global climate model run under
``business-as-usual'' forcing (the A2 CO2 emission scenario
from the IPCC's fourth assessment report), Hazen et al. (2013) found a
substantial loss of core habitat for a number of highly migratory
species, and small gains in viable habitat for other species, including
Pacific bluefin tuna. Although the net change in total potential
Pacific bluefin tuna core habitat was positive, the projected physical
changes in the bluefin tuna's migratory pathway could negatively impact
them. The northward displacement of the NPTZ and TZCF could lead to
longer migrations requiring greater energy expenditure. The generally
lower productivity of the region could also diminish the abundance or
quality of the Pacific bluefin tuna prey base.
A recent study of projected climate change in the North Pacific
that used an ensemble of 11 climate models, including measures of
primary and secondary production, found that increasing temperatures
could alter the spatial distribution of tuna and billfish species
across the North Pacific (Woodworth-Jefcoats et al., 2016). As with
Hazen et al. (2013), this study found species richness increasing to
the north following the northward displacement of the NPTZ. They also
estimated a 2-5 percent per decade decline in overall carrying capacity
for commercially important tuna and billfish species, driven by warming
waters and a basin-scale decline in zooplankton densities (Woodworth-
Jefcoats et al., 2016). While there is still substantial uncertainty
inherent in these climate models, we can say with some confidence that
the central North Pacific, which encompasses a key conduit between
Pacific bluefin tuna spawning and foraging habitat, is likely to become
warmer and less productive through the 21st century.
Increasing Ocean Acidification and Decreasing Dissolved Oxygen
As CO2 uptake by the oceans increases, ocean pH will
continue to decrease (Feely et al., 2009), with declines of between 0.2
and 0.4 expected in the western North Pacific by 2100 under the
Intergovernmental Panel on Climate Change's Representative
Concentration Pathway (RCP) 8.5 (Ciais et al., 2013). RCP 8.5 is a high
emission scenario, which assumes that radiative forcing due to
greenhouse gas emissions will continue to increase strongly throughout
the 21st century (Riahi et al., 2011). Rearing experiments on larval
yellowfin tuna suggest that ocean acidification may result in longer
hatch times, sub-lethal organ damage, and decreased growth and survival
(Bromhead et al., 2014; Frommel et al., 2016). Other studies on coral
reef fish larvae show that acidification can impair sensory abilities
of larvae, and in combination with warming temperatures, can negatively
affect metabolic scope (Munday et al., 2009a,b; Dixson et al., 2010;
Simpson et al., 2011). Surface ocean pH on Pacific bluefin tuna
spawning grounds is currently higher than that in the broader North
Pacific (8.1-8.2) (Feely et al., 2009). How this may affect the ability
of Pacific bluefin tuna larvae (in particular) to adapt to ocean
acidification is unknown. Recent studies have shown that future
adaptation to rising CO2 and acidification could be
facilitated by individual genetic variability (Schunter et al., 2017).
In addition, transgenerational plasticity may allow surprisingly rapid
adaptation across generations (Rummer & Munday 2017). However, these
studies examined small coral reef fish species, so results may not
transfer to larger, highly migratory species such as Pacific bluefin
tuna. As well as incurring direct effects on Pacific bluefin tuna,
ocean acidification is also likely to change the prey base available to
all life stages of this species. Different organisms vary substantially
in their sensitivity to the combined effects of acidification and
warming (Byrne 2011). A shift in the prey assemblage towards organisms
more tolerant to acidification is therefore likely in the future.
Current projections estimate a future decline in dissolved oxygen
of 3-6 percent by 2100 under RCP 8.5 (Bindoff et al., 2013; Ciais et
al., 2013). This may be most relevant for spawning-sized adult Pacific
bluefin tuna, which may be subject to greater metabolic stress on
spawning grounds. While some studies exist on the effects of
temperature on metabolic rates, cardiac function and specific dynamic
action in juvenile Pacific bluefin tuna (e.g. Blank et al., 2004; 2007;
Clark et al., 2008; 2010; 2013; Whitlock et al., 2015), there are no
published studies on larger adults, or on larvae. While future warming
and decreases in dissolved oxygen may reduce the suitability of some
parts of the Pacific bluefin tuna range (e.g. Muhling et al., 2016),
likely biological responses to this are not yet known.
Another factor to include in considerations of climate change
impacts is biogeochemical changes. Driven by upper ocean warming,
changes in source waters, enhanced stratification, and reduced mixing,
the dissolved oxygen content of mid-depth oceanic waters is expected to
decline (Keeling et al., 2010). This effect is especially important in
the eastern Pacific, where the Oxygen Minimum Zone (OMZ) shoals to
depths well within the vertical habitat of Pacific bluefin tuna and
other highly migratory species and, in particular, their prey (Stramma
et al., 2010; Moffit et al., 2015). The observed trend of declining
oxygen levels in the Southern California Bight (Bograd et al., 2008;
McClatchie et al., 2010; Bograd et al., 2015), combined with an
increase in the frequency and severity of hypoxic events along the U.S.
West Coast (Chan et al., 2008; Keller et al., 2010; Booth et al.,
2012), suggests that declining oxygen content could drive ecosystem
change. Specifically, the vertical compression of viable habitat for
some benthic and pelagic species could alter the available prey base
for Pacific bluefin tuna. Given that Pacific bluefin tuna are
opportunistic feeders, they could have resilience to these climate-
driven changes in their prey base.
The effects of increasing hypoxia on marine fauna in the California
Current may be magnified by ocean acidification. Ekstrom et al. (2015)
predicted the West Coast is highly vulnerable to ecological impacts of
ocean acidification due to reduction in aragonite saturation state
exacerbated by coastal upwelling of ``corrosive,'' lower pH waters
(Feely et al., 2008). The most
[[Page 37075]]
acute impacts would be on calcifying organisms (some marine
invertebrates and pteropods), which are not generally part of the adult
Pacific bluefin tuna diet. While direct impacts of ocean acidification
on Pacific bluefin tuna may be minimal within their eastern Pacific
foraging grounds, some common Pacific bluefin tuna prey do rely on
calcifying organisms (Fabry et al., 2008).
Climate Change Conclusions
We find that ocean acidification and changes in dissolved oxygen
content due to climate change pose a very low risk to the decline or
degradation of the Pacific bluefin tuna on the short-term time scale
(25 years), and low to moderate threat on the long-time scale (100
years). The reasoning behind this decision for acidification centered
primarily on the disconnect between Pacific bluefin tuna and the lower
trophic level prey which would be directly affected by acidification as
well as by the lack of information on direct impacts on acidification
on pelagic fish. Conclusions by the SRT members on the rising SST due
to climate change required SEDM, as the range of values assigned by
each SRT member was large. Following the SEDM, the SRT concluded that
SST rise poses a low risk of contributing to population decline or
degradation in PBF over the short (25 year) and long (100 year) time
frames. This decision was reached primarily due to the highly migratory
nature of Pacific bluefin tuna; despite likely latitudinal shifts in
preferred habitat, it would take little effort for Pacific bluefin tuna
to shift their movements along with the changing conditions.
Fukushima Associated Radiation
On 11 March, 2011, the T[omacr]hoku megathrust earthquake at
magnitude 9.1 produced a devastating tsunami that hit the Pacific coast
of Japan. As a result of the earthquake, the Fukushima Daiichi Nuclear
Power Plant was compromised, releasing radionuclides directly into the
adjacent sea. The result was a 1- to 2-week pulse of emissions of the
caesium radioisotopes Caesium-134 and Caesium-137. These isotopes were
biochemically available to organisms in direct contact with the
contaminated water (Oozeki et al., 2017).
Madigan et al. (2012) reported on the presence of Caesium-134 and
Caesium-137 in Pacific bluefin tuna caught in California in ratios that
strongly suggested uptake as a result of the Fukushima Daiichi
accident. The results indicated that highly migratory species can be
vectors for the trans-Pacific movement of radionuclides. Importantly,
the study highlighted that while the radiocaesium present in the
Pacific bluefin tuna analyzed was directly traceable to the Fukushima
accident, the concentrations were 30 times lower than background levels
of naturally occurring radioisotopes such as potassium-40. In addition,
Madigan et al. (2012) estimated the dose to human consumers of fish
from Fukushima derived Caesium-137 was at 0.5 percent of the dose from
Polonium-210, a natural decay product of Uranium-238, which is
ubiquitously present and in constant concentrations globally.
Fisher et al. (2013) further evaluated the dosage and associated
risks to marine organisms and humans (by consumption of contaminated
seafood) of the caesium radioisotopes associated with the Fukushima
Daiichi accident. They confirmed that dosage of radioisotopes from
consuming seafood were dominated by naturally occurring radionuclides
and that those stemming directly from Fukushima derived radiocaesium
were three to four orders of magnitude below doses from these natural
radionuclides. Doses to marine organisms were two orders of magnitude
lower than the lowest benchmark protection level for ecosystem health
(ICRP 2008). The study concluded that even on the date at which the
highest exposure levels may have been reached, dosages were very
unlikely to have exceeded reference levels. This indicates that the
amount of Fukushima derived radionuclides is not cause for concern with
regard to the potential harm to the organisms themselves.
We find that Fukushima associated radiation poses no risk of
contributing to population decline or degradation in Pacific bluefin
tuna. This was based largely on the absence of empirical evidence
showing negative effects of Fukushima derived radiation on Pacific
bluefin tuna.
Small Population Concerns
Small populations face a number of inherent risks. These risks are
tied to survival and reproduction (e.g. Allee or other depensation
effects) via three mechanisms: Ecological (e.g., mate limitation,
cooperative defense, cooperative feeding, and environmental
conditioning), genetic (e.g., inbreeding and genetic drift), and
demographic stochasticity (i.e., individual variability in survival and
recruitment) (Berec et al., 2007). The actual number at which
populations would be considered critically low and at risk varies
depending on the species and the risk being considered. While the
Pacific bluefin tuna is estimated to contain at least 1.6 million
individuals, of which more than 140,000 are reproductively capable, the
SRT deemed it prudent to examine the factors above that are
traditionally used to evaluate the impacts of relatively low population
numbers. In the paragraphs that follow we discuss how small population
size can affect reproduction, demographic stochasticity, genetics, and
how it can be affected by stochastic and catastrophic events, and Allee
effects.
In small populations, individuals may have difficulty finding a
mate. However, the probability of finding a mate depends largely on
density on the spawning grounds rather than absolute abundance. Pacific
bluefin tuna are a schooling species and individual Pacific bluefin
tuna are not randomly distributed throughout their range. They also
exhibit regular seasonal migration patterns that include aggregating at
two separate spawning grounds (Kitigawa et al., 2010). This schooling
and aggregation behavior serves to increase their local density and the
probability of individuals finding a mate. This mating strategy could
reduce the effects of small population size on finding mates over other
strategies that do not concentrate individuals. It is unknown whether
spawning behavior is triggered by environmental conditions or densities
of tuna. If density of adults triggers spawning, then reproduction
could be affected by high levels of depletion. However, the abundance
of Pacific bluefin tuna has reached similar lows in the past and
rebounded. The number of adult Pacific bluefin tuna is currently
estimated to be 2.6 percent of its unfished SSB. The number of adult
Pacific bluefin tuna reached a similar low in 1984 of 1.8 percent and
rebounded in the 1990s to 9.6 percent, the second highest level since
1952.
Another concern with small populations is demographic
stochasticity. Demographic stochasticity refers to the variability of
annual population change arising from random birth and death events at
the individual level. When populations are very small (e.g., <100
individuals), chance demographic events can have a large impact on the
population. Species with low mean annual survival rates are generally
at greater population risk from demographic stochasticity than those
that are long-lived and have high mean annual survival rates. In other
words, species that are long-lived and have high annual survival rates
have lower ``safe'' abundance thresholds, above which the risk of
extinction due to chance demographic processes becomes negligible. Even
though the percentage of adult Pacific bluefin tuna relative to
historical levels is low, they still
[[Page 37076]]
number in the hundreds of thousands. In addition, the total population
size in 2014 as estimated by the 2016 ISC stock assessment was
1,625,837. The high number of individuals, both mature and immature,
should therefore counteract a particular year with low survivorship.
Small populations may also face Allee effects. If a population is
critically small in size, Allee effects can act upon genetic diversity
to reduce the prevalence of beneficial alleles through genetic drift.
This may lower the population's fitness by reducing adaptive potential
and increasing the accumulation of deleterious alleles due to increased
levels of inbreeding. Population genetic theory typically sets a
threshold of 50 individuals (i.e., 25 males, 25 females) below which
irreversible loss of genetic diversity is likely to occur in the near
future. This value, however, is not necessarily based upon the number
of individuals present in the population (i.e., census population size,
NC) but rather on the effective population size
(NE), which is linked to the overall genetic diversity in
the population and is typically less than NC. In extreme
cases NE may be much (e.g. 10-10,000 times) smaller,
typically for species that experience high variance in reproductive
success (e.g., sweepstakes recruitment events). NE may also
be reduced in populations that deviate from a 1:1 sex ratio and from
species that have suffered a genetic bottleneck.
With respect to considerations of NE in Pacific bluefin
tuna, the following points are relevant. Although there are no
available data for nuclear DNA diversity in Pacific bluefin tuna, the
relatively high number of unique mitochondrial DNA haplotypes (Tseng et
al., 2014) can be used as a proxy for evidence of high levels of
overall genetic diversity currently within the population. With two
separate spawning grounds, and adult numbers remaining in the hundreds
of thousands, genetic diversity is expected to still be at high levels
with little chance for inbreeding, given that billions of gametes
combine in concentrated spawning events.
Animals that are highly mobile with a large range are less
susceptible to stochastic and catastrophic events (such as oil spills)
than those that occur in concentrated areas across life history stages.
Pacific bluefin tuna are likely to be resilient to catastrophic and
stochastic events for the following reasons: (1) They are highly
migratory, (2) there is a large degree of spatial separation between
life history stages, (3) there are two separated spawning areas, and
(4) adults reproduce over many years such that poor recruitment even
over a series of years will not result in reproductive collapse. As
long as this spatial arrangement persists and poor recruitment years do
not exceed the reproductive age span for the species, Pacific bluefin
tuna should be resilient to both stochastic and catastrophic events.
Although Pacific bluefin tuna are resilient to many of the risks
that small populations face, there is increasing evidence for a
reduction in population growth rate for marine fishes that have been
fished to densities below those expected from natural fluctuations
(Hutchings 2000, 2001). These studies focus on failure to recover at
expected rates. A far more serious issue is not just reducing
population growth but reducing it to the point that populations
decrease (death rates exceed recruitment). Unfortunately, the reviews
of marine fish stocks do not make a distinction between these two
important categories of depensation: Reduced but neutral or positive
growth versus negative growth. Many of the cases reviewed suggested
depensatory effects for populations reduced to relatively low levels
(0.2 to 0.5 SSBmsy) that would increase time to recovery,
but no mention was made of declining towards extinction. However, these
cases did not represent the extent of reduction observed in Pacific
bluefin tuna (0.14 SSBmsy). Thus, this case falls outside
that where recovery has been observed in other marine fishes and thus
there remains considerable uncertainty as to how the species will
respond to reductions in fishing pressure.
Hutchings et al. (2012) also show that there is no positive
relationship between per capita population growth rate and fecundity in
a review of 233 populations of teleosts. Thus, the prior confidence
that high fecundity provides more resilience to population reduction
and ability to quickly recover should be abandoned. These findings,
although not providing examples that marine fishes exploited to low
levels will decline towards extinction, suggest that at a minimum such
populations may not recover quickly. However, Pacific bluefin tuna
recently showed an instance of positive growth from a population level
similar to the most recent stock assessment. This suggests potential
for recovery at low population levels. However, the conditions needed
to allow positive growth remain uncertain.
Small Populations Conclusion
We find that small population concerns pose low risk of
contributing to population decline or degradation in Pacific bluefin
tuna over both the 25- and 100-year time scales, though with low
certainty. This was largely due to the estimated population size of
more than 1.6 million individuals, of which at least 140,000 are
reproductively capable. This, coupled with previous evidence of
recovery from similarly low numbers and newly implemented harvest
regulations, strongly suggests that small population concerns are not
particularly serious in Pacific bluefin tuna.
Analysis of Threats
As noted previously, the SRT conducted its analysis in a 3-step
progressive process. First, the SRT evaluated the risk of 25 different
threats (covering all of the ESA section 4(a)(1) categories)
contributing to a decline or degradation of Pacific bluefin tuna. The
second step was to evaluate the extinction risk in each of the 4(a)(1)
categories. Finally, they performed an overall extinction risk analysis
over two timeframes--25 years and 100 years.
In step one, the evaluation of the risk of individual threats
contributing to a decline or degradation of Pacific bluefin tuna
considered how these threats have affected and how they are expected to
continue to affect the species. The threats were evaluated in light of
the vulnerability of and exposure to the threat, and the biological
response. This evaluation of individual threats and the potential
demographic risk they pose forms the basis of understanding used during
the extinction risk analysis to inform the overall assessment of
extinction risk.
Within each threat category, individual threats have not only
different magnitudes of influence on the overall risk to the species
(weights) but also different degrees of certainty. The overall threat
within a category is cumulative across these individual threats. Thus,
the overall threat is no less than that for the individual threat with
the highest influence but may be greater as the threats are taken
together. For example, some of the individual threats rated as
``moderate'' may result in an overall threat for that category of at
least ``moderate'' but potentially ``high.'' When evaluating the
overall threat, individual team members considered all threats taken
together and performed a mental calculation, weighting the threats
according to their expertise using the definitions below.
Each team member was asked to record his or her confidence in their
overall scoring for that category. If, for example, the scoring for the
overall threat confidence was primarily a function of a single threat
and that threat had a high level of certainty, then
[[Page 37077]]
they would likely have a high level of confidence in the overall
confidence score. Alternatively, the overall confidence score could be
reduced due to a combination of threats, some of which the team members
had a low level of certainty about and consequently communicated this
lower overall level of confidence with a corresponding score (using the
definitions below). Generally, the level of confidence will be most
influenced by the level of certainty in the threats of highest
severity. The level of confidence for threats with no to low severity
within a category that contains moderate to high severity threats will
not be important to the overall level of confidence.
The level of severity is defined as the level of risk of this
threat category contributing to the decline or degradation of the
species over each time frame (over the next 25 years or over the next
100 years). Specific rankings for severity are: (1) High: The threat
category is likely to eliminate or seriously degrade the species; (2)
moderate: The threat category is likely to moderately degrade the
species; (3) low: The threat category is likely to only slightly impair
the species; and (4) none: The threat category is not likely to impact
the species.
The level of confidence is defined as the level of confidence that
the threat category is affecting, or is likely to affect, the species
over the time frame considered. Specific rankings for confidence are:
(1) High: There is a high degree of confidence to support the
conclusion that this threat category is affecting, or is likely to
affect, the species with the severity ascribed over the time frame
considered; (2) moderate: There is a moderate degree of confidence to
support the conclusion that this threat category is affecting, or is
likely to affect, the species with the severity ascribed over the time
frame considered; (3) low: There is a low degree of confidence to
support the conclusion that this threat category is affecting, or is
likely to affect, the species with the severity ascribed over the time
frame considered; and (4) none: There is no confidence to support the
conclusion that this threat category is affecting, or is likely to
affect, the species with the severity ascribed over the time frame
considered.
Based on the best available information and the SRT's SEDM
analysis, we find that overutilization, particularly by commercial
fishing activities, poses a moderate risk of decline or degradation of
the species over both the 25 and 100-year time scales. While the degree
of certainty for this risk assessment was moderate for the 25-year time
frame, it was low for the 100-year time frame. This largely reflects
the inability to accurately predict trends in both population size and
catch over the longer time frame. In addition, management regimes may
shift in either direction in response to the population trends at the
time.
Over the short and long time frames, we find that habitat
destruction, disease, and predation are not likely to pose a risk to
the extinction of the Pacific bluefin tuna. Among the specific threats
in the Habitat Destruction category, water pollution was ranked the
highest (mean severity score 1.5). This was largely due to the fact
that any degradation to Pacific bluefin tuna by water pollution is a
passive event. That is, behavioral avoidance might not be possible,
whereas other specific threats involved factors where active avoidance
would be possible.
We also find that based on the best available information and the
SRT's SEDM analysis, the inadequacy of existing regulatory mechanisms
poses a low risk of decline or degradation to the species over both the
25- and 100-year time scales, given the stable or upward trends of
future projected SSB over the short time scale from various harvest
scenarios in the 2016 ISC stock assessment. The confidence levels were
moderate for the 25-year time frame and low for the 100-year time
frame.
Lastly, we find that other natural or manmade factors, which
included climate change and small population concerns, pose a low risk
of decline or degradation to the species over the 25-year time frame
and moderate risk over the 100-year time frame.
Extinction Risk Analysis
As described previously, following the evaluation of the risk of 25
specific threats contributing to the decline or degradation of Pacific
bluefin tuna, the SRT then conducted step 2 and step 3 to perform an
extinction risk analysis. In step two the SRT used SEDM to evaluate the
contribution of each section 4(a)(1) factor to extinction risk.
Finally, in step 3 the SRT performed an overall extinction risk
analysis over two timeframes--25 years and 100 years.
This final risk assessment considered the threats, the results from
the recent stock assessment, the species life history, and historical
trends. After considering all factors, team members were asked to
distribute 100 plausibility points into one of three risk categories
for the short term and long term time frames. The short-term time frame
was 25 years and the long-term time frame was 100 years.
The SRT defined the extinction risk categories as low, moderate,
and high. The species is deemed to be at low risk of extinction if at
least one of the following conditions is met: (1) The species has high
abundance or productivity; (2) There are stable or increasing trends in
abundance; and (3) The distributional characteristics of the species
are such that they allow resiliency to catastrophes or environmental
changes. The species is deemed to be at moderate risk of extinction if
it is not at high risk and at least one of the following conditions is
met: (1) There are unstable or decreasing trends in abundance or
productivity which are substantial relative to overall population size;
(2) There have been reductions in genetic diversity; or (3) The
distributional characteristics of the species are such that they make
the species vulnerable to catastrophes or environmental changes.
Finally, the species is deemed to be at high risk of extinction if at
least one of the following conditions is met: (1) The abundance of the
species is such that depensatory effects are plausible; (2) There are
declining trends in abundance that are substantial relative to overall
population size; (3) There is low and decreasing genetic diversity; (4)
There are current or predicted environmental changes that may strongly
and negatively affect a life history stage for a significant period of
time; or (5) The species has distributional characteristics that result
in vulnerability to catastrophes or environmental changes.
The SRT members distributed their plausibility points across all
three risk categories, with most members placing their points in the
low and moderate risk categories. Over the 25-year time frame, a large
proportion of plausibility points were assigned to the low and moderate
risk by some team members. Over the 100-year time frame, more points
were assigned to the moderate risk category by all members and a few
members assigned points to the high risk category. After the scores
were recorded, the SRT calculated the average number of points for each
risk category under both the 25 and 100-year timeframes. For both
timeframes, the greatest number of points were in the low risk
category. The average number of points for the low risk category was 68
for the 25-year timeframe and 51 for the 100-year timeframe.
There are a number of factors that contributed to the low ranking
of the overall extinction risk over both the 25 and 100-year time
frames. The large number of mature individuals, while small relative to
the theoretical, model-derived unfished population, coupled
[[Page 37078]]
with the total estimated population size, was deemed sufficiently large
for Pacific bluefin tuna to avoid small population effects. Harvest
regulations have been adopted by member nations to reduce landings and
rebuild the population, with all model results from the ISC analysis
showing stable or increasing trends under current management measures.
Also, the SRT noted that over the past 40 years the SSB has been low
relative to the theoretical, model-derived unfished population (less
than 10 percent of unfished), and it has increased before. While the
SRT agreed that climate change has the potential to negatively impact
the population, many members of the team felt that the Pacific bluefin
tuna's broad distribution across habitat, vagile nature, and generalist
foraging strategy were mitigating factors in terms of extinction risk.
After evaluating the extinction risk SEDM analysis conducted by the
SRT over the 25-year and 100-year timeframes, we considered the overall
extinction risk categories described below:
High risk: A species or DPS with a high risk of extinction is at or
near a level of abundance, productivity, spatial structure, and/or
diversity that places its continued persistence in question. The
demographics of a species or DPS at such a high level of risk may be
highly uncertain and strongly influenced by stochastic or depensatory
processes. Similarly, a species or DPS may be at high risk of
extinction if it faces clear and present threats (e.g., confinement to
a small geographic area; imminent destruction, modification, or
curtailment of its habitat; or disease epidemic) that are likely to
create present and substantial demographic risks.
Moderate risk: A species or DPS is at moderate risk of extinction
if it is on a trajectory that puts it at a high level of extinction
risk in the foreseeable future (see description of ``High risk''
above). A species or DPS may be at moderate risk of extinction due to
projected threats or declining trends in abundance, productivity,
spatial structure, or diversity. The appropriate time horizon for
evaluating whether a species or DPS is more likely than not to be at
high risk in the foreseeable future depends on various case- and
species-specific factors. For example, the time horizon may reflect
certain life history characteristics (e.g., long generation time or
late age-at-maturity) and may also reflect the time frame or rate over
which identified threats are likely to impact the biological status of
the species or DPS (e.g., the rate of disease spread). (The appropriate
time horizon is not limited to the period that status can be
quantitatively modeled or predicted within predetermined limits of
statistical confidence. The biologist (or Team) should, to the extent
possible, clearly specify the time horizon over which it has confidence
in evaluating moderate risk.)
Low risk: A species or DPS is at low risk of extinction if it is
not at moderate or high level of extinction risk (see ``Moderate risk''
and ``High risk'' above). A species or DPS may be at low risk of
extinction if it is not facing threats that result in declining trends
in abundance, productivity, spatial structure, or diversity. A species
or DPS at low risk of extinction is likely to show stable or increasing
trends in abundance and productivity with connected, diverse
populations.
The SRT evaluation of extinction risk placed the majority of
distributed points in the low risk category for both the 25-year and
100-year timeframes. The SRT members explained their assessment of low
risk over those timeframes recognizing that the large number of mature
individuals, while small relative to the theoretical, model-derived
unfished population, coupled with the total estimated population size,
was deemed sufficiently large for Pacific bluefin tuna to avoid small
population effects. Harvest regulations have been adopted by member
nations to reduce landings and rebuild the population, with all model
results from the ISC stock assessment analysis (ISC 2016) showing
stable or increasing trends under current management measures. Also,
the SRT noted that over the past 40 years the SSB has been low relative
to the theoretical, model-derived unfished population (less than 10
percent of unfished), and it has increased before. While the SRT agreed
that climate change has the potential to negatively impact the
population, many members of the team felt that the Pacific bluefin
tuna's broad distribution across habitat, its vagile nature, and its
generalist foraging strategy were mitigating factors in terms of
extinction risk.
Based upon the expert opinion of the SRT and for the reasons
described above, we determine that the overall extinction risk to
Pacific bluefin tuna is most accurately characterized by the
description of the low risk category as noted above.
Review of Conservation Efforts
Section 4(b)(1) of the ESA requires that NMFS make listing
determinations based solely on the best scientific and commercial data
available after conducting a review of the status of the species and
taking into account those efforts, if any, being made by any state or
foreign nation, or political subdivisions thereof, to protect and
conserve the species. We are not aware of additional conservation
efforts being made by any state or foreign nation to protect and
conserve the species other than the fishery management agreements
already considered, thus no additional measures were evaluated in this
finding.
Significant Portion of Its Range Analysis
As the definitions of ``endangered species'' and ``threatened
species'' make clear, the determination of extinction risk can be based
on either assessment of the rangewide status of the species, or the
status of the species in a ``significant portion of its range'' (SPR).
Because we determined that the Pacific bluefin tuna is at low risk of
extinction throughout its range, the species does not warrant listing
based on its rangewide status. Next, we needed to determine whether the
species is threatened or endangered in a significant portion of its
range. According to the SPR Policy (79 FR 37577; July 1, 2014), if a
species is found to be endangered or threatened in a significant
portion of its range, the entire species is listed as endangered or
threatened, respectively, and the ESA's protections apply to all
individuals of the species wherever found.
On March 29, 2017, the Arizona District Court in Center for
Biological Diversity, et al., v. Zinke, et al., 4:14-cv-02506-RM (D.
Ariz.), a case brought against the U.S. Fish and Wildlife Service
(FWS), remanded and vacated the joint FWS/NMFS SPR Policy after
concluding that the policy's definition of ``significant'' was invalid.
NMFS is not a party to the litigation. On April 26, 2017, the FWS filed
a Motion to Alter or Amend the Court's Judgment, which is pending. In
the meantime, we based our SPR analysis on our joint SPR Policy, as
discussed below.
The SPR Policy sets out the following three components:
(1) Significant: A portion of the range of a species is
``significant'' if the species is not currently endangered or
threatened throughout its range, but the portion's contribution to the
viability of the species is so important that, without the members in
that portion, the species would be in danger of extinction, or likely
to become so in the foreseeable future, throughout all of its range.
(2) The range of a species is considered to be the general
geographical area within which that species can be found at the time
NMFS
[[Page 37079]]
makes any particular status determination. This range includes those
areas used throughout all or part of the species' life cycle, even if
they are not used regularly (e.g., seasonal habitats). Lost historical
range is relevant to the analysis of the status of the species, but it
cannot constitute a SPR.
(3) If the species is endangered or threatened throughout a
significant portion of its range, and the population in that
significant portion is a valid DPS, we will list the DPS rather than
the entire taxonomic species or subspecies.
When we conduct a SPR analysis, we first identify any portions of
the range that warrant further consideration. The range of a species
can theoretically be divided into portions in an infinite number of
ways. However, there is no purpose to analyzing portions of the range
that are not reasonably likely to be of relatively greater biological
significance, or in which a species may not be endangered or
threatened. To identify only those portions that warrant further
consideration, we determine whether there is substantial information
indicating that (1) the portions may be significant and (2) the species
may be in danger of extinction in those portions or likely to become so
within the foreseeable future. We emphasize that answering these
questions in the affirmative is not a determination that the species is
endangered or threatened throughout a SPR, rather, it is a step in
determining whether a more detailed analysis of the issue is required.
Making this preliminary determination triggers a need for further
review, but does not prejudge whether the portion actually meets these
standards such that the species should be listed.
If this preliminary determination identifies a particular portion
or portions that may be significant and that may be threatened or
endangered, those portions must then be evaluated under the SPR Policy
as to whether the portion is in fact both significant and endangered or
threatened. In making a determination of significance under the SPR
Policy we would consider the contribution of the individuals in that
portion to the viability of the species. That is, we would determine
whether the portion's contribution to the viability of the species is
so important that, without the members in that portion, the species
would be in danger of extinction or likely to become so in the
foreseeable future. Depending on the biology of the species, its range,
and the threats it faces, it may be more efficient to address the
``significant'' question first, or the status question first. If we
determine that a portion of the range we are examining is not
significant, we would not need to determine whether the species is
endangered or threatened there; if we determine that the species is not
endangered or threatened in the portion of the range we are examining,
then we would not need to determine if that portion is significant.
Because Pacific bluefin tuna range broadly throughout their
lifecycle around the Pacific basin, there was no portion of the range
that, if lost, would increase the population's extinction risk. In
other words, risk of specific threats to Pacific bluefin tuna are
buffered both in space and time. To be thorough, the SRT examined the
potential for a SPR by considering the greatest known threats to the
species and whether these were localized to a significant portion of
the range of the species. The main threats to Pacific bluefin tuna
identified by the SRT were overutilization, inadequacy of management,
and climate change. Generally, these threats are spread throughout the
range of Pacific bluefin tuna and not localized to a specific region.
We also considered whether any potential SPRs might be identified
on the basis of threats faced by the species in a portion of its range
during one part of its life cycle. We further evaluated the potential
for the two known spawning areas to meet the two criteria for a SPR.
The spawning areas for Pacific bluefin tuna are likely to be somewhat
temporally and spatially fluid in that they are characterized by
physical oceanographic conditions (e.g., temperature) rather than a
spatially explicit area. While commercial fisheries target Pacific
bluefin tuna on the spawning grounds, spatial patterns of commercial
fishing have not changed significantly over many decades. The
historical pattern of exploitation on the spawning areas was part of
the consideration in evaluating the threat of overexploitation to the
species as a whole, and was determined to not significantly increase
the species' risk of extinction for the members utilizing that portion
of the range for the spawning stage of their life cycle. Given that the
species has persisted throughout this time frame and has experienced
similarly low levels of standing stock biomass, it has shown the
ability to rebound and has yet to reach critically low levels.
Therefore, it was determined that this fishery behavior has not
significantly increased the species' risk of extinction for this life
cycle phase.
Significant Portion of Its Range Determination
Pacific bluefin tuna range broadly throughout their life cycle
around the Pacific basin, and there is no portion of the range that
merits evaluation as a potential SPR. If a threat was determined to
impact the fish in the spawning area, it would impact the fish
throughout its range and, therefore, the species would warrant listing
as threatened or endangered based on its status throughout its entire
range. Based on our review of the best available information, we find
that there are no portions of the range of the Pacific bluefin tuna
that were likely to be of heightened biological significance (relative
to other areas) or likely to be either endangered or threatened
themselves.
Final Determination
Section 4(b)(1) of the ESA requires that NMFS make listing
determinations based solely on the best scientific and commercial data
available after conducting a review of the status of the species and
taking into account those efforts, if any, being made by any state or
foreign nation, or political subdivisions thereof, to protect and
conserve the species. We have independently reviewed the best available
scientific and commercial information including the petition, public
comments submitted on the 90-day finding (81 FR 70074; October 11,
2016), the status review report, and other published and unpublished
information, and have consulted with species experts and individuals
familiar with Pacific bluefin tuna. We considered each of the statutory
factors to determine whether it presented an extinction risk to the
species on its own, now or in the foreseeable future, and also
considered the combination of those factors to determine whether they
collectively contributed to the extinction risk of the species, now or
in the foreseeable future.
Our determination set forth here is based on a synthesis and
integration of the foregoing information, factors and considerations,
and their effects on the status of the species throughout its entire
range. Based on our consideration of the best available scientific and
commercial information, as summarized here and in the status review
report, we conclude that no population segments of the Pacific bluefin
tuna meet the DPS policy criteria and that the Pacific bluefin tuna
faces an overall low risk of extinction. Therefore, we conclude that
the species is not currently in danger of extinction throughout its
range nor is it
[[Page 37080]]
likely to become so within the foreseeable future. Additionally, we did
not identify any portions of the species' range that were likely to be
of heightened biological significance (relative to other areas) or
likely to be either endangered or threatened themselves. Accordingly,
the Pacific bluefin tuna does not meet the definition of a threatened
or endangered species, and thus, the Pacific bluefin tuna does not
warrant listing as threatened or endangered at this time.
This is a final action, and, therefore, we are not soliciting
public comments.
References
A complete list of all references cited herein is available upon
request (see FOR FURTHER INFORMATION CONTACT).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 3, 2017.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2017-16668 Filed 8-7-17; 8:45 am]
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