Endangered and Threatened Wildlife; 90-day Finding on a Petition To List the Bigeye Thresher Shark as Threatened or Endangered Under the Endangered Species Act, 48061-48069 [2015-19551]
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Federal Register / Vol. 80, No. 154 / Tuesday, August 11, 2015 / Proposed Rules
Dated: August 5, 2015.
Samuel D. Rauch III,
Deputy Assistant Administrator for
Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2015–19550 Filed 8–10–15; 8:45 am]
BILLING CODE 3510–22–P
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric
Administration
50 CFR Parts 223 and 224
[Docket No. 150506426–5426–01]
RIN 0648–XD942
Endangered and Threatened Wildlife;
90-day Finding on a Petition To List the
Bigeye Thresher Shark as Threatened
or Endangered Under the Endangered
Species Act
National Marine Fisheries
Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA),
Commerce.
ACTION: 90-day petition finding, request
for information, and initiation of status
review.
AGENCY:
We, NMFS, announce the 90day finding on a petition to list the
bigeye thresher shark (Alopias
superciliosus) range-wide, or in the
alternative, as one or more distinct
population segments (DPSs) identified
by the petitioners as endangered or
threatened under the U.S. Endangered
Species Act (ESA). We find that the
petition presents substantial scientific
or commercial information indicating
that the petitioned action may be
warranted for the species worldwide.
Accordingly, we will initiate a status
review of bigeye thresher shark rangewide at this time. To ensure that the
status review is comprehensive, we are
soliciting scientific and commercial
information regarding this species.
DATES: Information and comments on
the subject action must be received by
October 13, 2015.
ADDRESSES: You may submit comments,
information, or data, identified by
‘‘NOAA–NMFS–2015–0089’’ by any one
of the following methods:
• Electronic Submissions: Submit all
electronic public comments via the
Federal eRulemaking Portal. Go to
www.regulations.gov/
#!docketDetail;D=NOAA-NMFS-20150089. Click the ‘‘Comment Now’’ icon,
complete the required fields, and enter
or attach your comments.
• Mail or hand-delivery: Office of
Protected Resources, NMFS, 1315 East-
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SUMMARY:
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West Highway, Silver Spring, MD
20910.
Instructions: You must submit
comments by one of the above methods
to ensure that we receive, document,
and consider them. Comments sent by
any other method, to any other address
or individual, or received after the end
of the comment period, may not be
considered. All comments received are
a part of the public record and will
generally be posted for public viewing
on https://www.regulations.gov without
change. All personal identifying
information (e.g., name, address, etc.),
confidential business information, or
otherwise sensitive information
submitted voluntarily by the sender will
be publicly accessible. We will accept
anonymous comments (enter ‘‘N/A’’ in
the required fields if you wish to remain
anonymous). Attachments to electronic
comments will be accepted in Microsoft
Word, Excel, or Adobe PDF file formats
only
FOR FURTHER INFORMATION CONTACT:
Chelsey Young, NMFS, Office of
Protected Resources (301) 427–8491.
SUPPLEMENTARY INFORMATION:
Background
On April 27, 2015, we received a
petition from Defenders of Wildlife
requesting that we list the bigeye
thresher shark (Alopias superciliosus) as
endangered or threatened under the
ESA, or, in the alternative, to list one or
more distinct population segments
(DPSs), should we find they exist, as
threatened or endangered under the
ESA. Defenders of Wildlife also
requested that critical habitat be
designated for this species in U.S.
waters concurrent with final ESA
listing. The petition states that the
bigeye thresher shark merits listing as
an endangered or threatened species
under the ESA because of the following:
(1) The species faces threats from
historical and continued fishing for both
commercial and recreational purposes;
(2) life history characteristics and
limited ability to recover from fishing
pressure make the species particularly
vulnerable to overexploitation; and (3)
regulations are inadequate to protect the
bigeye thresher shark.
ESA Statutory Provisions and Policy
Considerations
Section 4(b)(3)(A) of the ESA of 1973,
as amended (U.S.C. 1531 et seq.),
requires, to the maximum extent
practicable, that within 90 days of
receipt of a petition to list a species as
threatened or endangered, the Secretary
of Commerce make a finding on whether
that petition presents substantial
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scientific or commercial information
indicating that the petitioned action
may be warranted, and promptly
publish the finding in the Federal
Register (16 U.S.C. 1533(b)(3)(A)). When
we find that substantial scientific or
commercial information in a petition
and in our files indicates the petitioned
action may be warranted (a ‘‘positive 90day finding’’), we are required to
promptly commence a review of the
status of the species concerned, which
includes conducting a comprehensive
review of the best available scientific
and commercial information. Within 12
months of receiving the petition, we
must conclude the review with a finding
as to whether, in fact, the petitioned
action is warranted. Because the finding
at the 12-month stage is based on a
significantly more thorough review of
the available information, a ‘‘may be
warranted’’ finding at the 90-day stage
does not prejudge the outcome of the
status review.
Under the ESA, a listing
determination may address a ‘‘species,’’
which is defined to also include
subspecies and, for any vertebrate
species, any DPS that interbreeds when
mature (16 U.S.C. 1532(16)). A joint
NMFS–U.S. Fish and Wildlife Service
(USFWS) policy clarifies the agencies’
interpretation of the phrase ‘‘distinct
population segment’’ for the purposes of
listing, delisting, and reclassifying a
species under the ESA (‘‘DPS Policy’’;
61 FR 4722; February 7, 1996). A
species, subspecies, or DPS is
‘‘endangered’’ if it is in danger of
extinction throughout all or a significant
portion of its range, and ‘‘threatened’’ if
it is likely to become endangered within
the foreseeable future throughout all or
a significant portion of its range (ESA
sections 3(6) and 3(20), respectively; 16
U.S.C. 1532(6) and (20)). Pursuant to the
ESA and our implementing regulations,
the determination of whether a species
is threatened or endangered shall be
based on any one or a combination of
the following five section 4(a)(1) factors:
The present or threatened destruction,
modification, or curtailment of habitat
or range; overutilization for commercial,
recreational, scientific, or educational
purposes; disease or predation;
inadequacy of existing regulatory
mechanisms; and any other natural or
manmade factors affecting the species’
existence (16 U.S.C. 1533(a)(1), 50 CFR
424.11(c)).
ESA-implementing regulations issued
jointly by NMFS and USFWS (50 CFR
424.14(b)) define ‘‘substantial
information’’ in the context of reviewing
a petition to list, delist, or reclassify a
species as the amount of information
that would lead a reasonable person to
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believe that the measure proposed in the
petition may be warranted. When
evaluating whether substantial
information is contained in a petition,
we must consider whether the petition:
(1) Clearly indicates the administrative
measure recommended and gives the
scientific and any common name of the
species involved; (2) contains detailed
narrative justification for the
recommended measure, describing,
based on available information, past and
present numbers and distribution of the
species involved and any threats faced
by the species; (3) provides information
regarding the status of the species over
all or a significant portion of its range;
and (4) is accompanied by the
appropriate supporting documentation
in the form of bibliographic references,
reprints of pertinent publications,
copies of reports or letters from
authorities, and maps (50 CFR
424.14(b)(2)).
At the 90-day stage, we evaluate the
petitioner’s request based upon the
information in the petition, including its
references, and the information readily
available in our files. We do not conduct
additional research, and we do not
solicit information from parties outside
the agency to help us in evaluating the
petition. We will accept the petitioner’s
sources and characterizations of the
information presented, if they appear to
be based on accepted scientific
principles, unless we have specific
information in our files that indicates
the petition’s information is incorrect,
unreliable, obsolete, or otherwise
irrelevant to the requested action.
Information that is susceptible to more
than one interpretation or that is
contradicted by other available
information will not be dismissed at the
90-day finding stage, so long as it is
reliable and a reasonable person would
conclude that it supports the
petitioner’s assertions. Conclusive
information indicating the species may
meet the ESA’s requirements for listing
is not required to make a positive 90day finding. We will not conclude that
a lack of specific information alone
negates a positive 90-day finding, if a
reasonable person would conclude that
the unknown information itself suggests
an extinction risk of concern for the
species at issue.
To make a 90-day finding on a
petition to list a species, we evaluate
whether the petition presents
substantial scientific or commercial
information indicating the subject
species may be either threatened or
endangered, as defined by the ESA.
First, we evaluate whether the
information presented in the petition,
along with the information readily
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available in our files, indicates that the
petitioned entity constitutes a ‘‘species’’
eligible for listing under the ESA. Next,
we evaluate whether the information
indicates that the species at issue faces
extinction risk that is cause for concern;
this may be indicated in information
expressly discussing the species’ status
and trends, or in information describing
impacts and threats to the species. We
evaluate any information on specific
demographic factors pertinent to
evaluating extinction risk for the species
at issue (e.g., population abundance and
trends, productivity, spatial structure,
age structure, sex ratio, diversity,
current and historical range, habitat
integrity or fragmentation), and the
potential contribution of identified
demographic risks to extinction risk for
the species. We then evaluate the
potential links between these
demographic risks and the causative
impacts and threats identified in ESA
section 4(a)(1).
Information presented on impacts or
threats should be specific to the species
and should reasonably suggest that one
or more of these factors may be
operative threats that act or have acted
on the species to the point that it may
warrant protection under the ESA.
Broad statements about generalized
threats to the species, or identification
of factors that could negatively impact
a species, do not constitute substantial
information that listing may be
warranted. We look for information
indicating that not only is the particular
species exposed to a factor, but that the
species may be responding in a negative
fashion; then we assess the potential
significance of that negative response.
Many petitions identify risk
classifications made by nongovernmental organizations, such as the
International Union for the
Conservation of Nature (IUCN), the
American Fisheries Society, or
NatureServe, as evidence of extinction
risk for a species. Risk classifications by
other organizations or made under other
Federal or state statutes may be
informative, but such classification
alone may not provide the rationale for
a positive 90-day finding under the
ESA. For example, as explained by
NatureServe, their assessments of a
species’ conservation status do ‘‘not
constitute a recommendation by
NatureServe for listing under the U.S.
Endangered Species Act’’ because
NatureServe assessments ‘‘have
different criteria, evidence
requirements, purposes and taxonomic
coverage than government lists of
endangered and threatened species, and
therefore these two types of lists should
not be expected to coincide’’ (https://
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www.natureserve.org/prodServices/pdf/
NatureServeStatusAssessmentsListingDec%202008.pdf). Thus, when a
petition cites such classifications, we
will evaluate the source of information
that the classification is based upon in
light of the standards on extinction risk
and impacts or threats discussed above.
Species Description
Distribution
The bigeye thresher shark (Alopias
superciliosus) is a large, highly
migratory oceanic and coastal species of
shark found throughout the world in
tropical and temperate seas. In the
Western Atlantic (including the Gulf of
Mexico), bigeye threshers can be found
off the Atlantic coast of the United
States (from New York to Florida), and
in the Gulf of Mexico off Florida,
Mississippi and Texas. They can also be
found in Mexico (from Veracruz to
Yucatan), Bahamas, Cuba, Venezuela, as
well as central and southern Brazil. In
the Eastern Atlantic, bigeye threshers
are found from Portugal to the Western
Cape of South Africa, including the
western and central Mediterranean Sea.
In the Indian Ocean, bigeye threshers
are found in South Africa (Eastern Cape
and KwaZulu-Natal), Madagascar,
Arabian Sea (Somalia), Gulf of Aden,
Maldives, and Sri Lanka. In the Pacific
Ocean, from West to East, bigeye
threshers are known from southern
Japan (including Okinawa), Taiwan
(Province of China), Vietnam, between
the Northern Mariana Islands and Wake
Island, down to the northwestern coast
of Australia and New Zealand. Moving
to the Central Pacific, bigeye threshers
are known from the area between Wake,
Marshall, Howland and Baker, Palmyra,
Johnston, Hawaiian Islands, Line
Islands, and between Marquesas and
Galapagos Islands. Finally, in the
Eastern Pacific, bigeye threshers occur
from Canada to Mexico (Gulf of
California) and west of Galapagos
Islands (Ecuador). They are also
possibly found off Peru and northern
Chile (Compagno, 2001).
Physical Characteristics
The bigeye thresher shark possesses
an elongated upper caudal lobe almost
equal to its body length, which is
unique to the Alopiidae family. It has a
broad head, a moderately long and
bulbous snout, curved yet broad-tipped
pectoral fins, distinctive grooves on the
head above the gills, and large teeth.
The first dorsal fin mid base is closer to
the pelvic-fin bases than to the pectoralfin bases. The caudal tip is broad with
a wide terminal lobe. While some of the
above characteristics may be shared by
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other thresher shark species, diagnostic
features separating this species from the
other two thresher shark species
(common thresher, A. vulpinus, and
pelagic thresher, A. pelagicus) are their
extremely large eyes, which extend onto
the dorsal surface of the head, and the
prominent notches that run dorso-lateral
from behind the eyes to behind the gills.
The body can be purplish grey or greybrown on the upper surface and sides,
with grey to white coloring on its
underside (light color of abdomen does
not extend over pectoral fin bases like
common thresher) and no white dot on
upper pectoral fin tips like those often
seen in common threshers (Compagno
2001).
per litter (Chen et al., 1997; Compagno,
´
2001; Moreno and Moron, 1992) and a
long gestation period of 12 months,
although this remains uncertain due to
a lack of birthing seasonality data (Liu
et al., 1998). They (like all thresher
sharks) are ovoviviparous and
oophagous (developing embryo in uteri
eat unfertilized eggs produced by the
ovary). Size at birth for the bigeye
thresher ranges from 64–106 cm TL
(Gilmore, 1993), but a mating season has
not yet been identified. Bigeye threshers
have the slowest population growth rate
of all thresher sharks, with an
exceptionally low potential annual rate
of population increase (0.02; IUCN;
´
l=1.009 yr¥1, Cortes, 2009).
Habitat
Bigeye thresher sharks are found in a
diverse spectrum of locations, including
coastal waters over continental shelves,
on the high seas in the epipelagic zone
far from land, in deep waters near the
bottom on continental slopes, and
sometimes in shallow inshore waters.
They are an epipelagic, neritic, and
epibenthic shark, ranging from the
surface and in the intertidal to at least
500 m deep, but mostly below 100 m
depth. In our files, we found
information indicating that bigeye
threshers prefer an optimum swimming
depth of 240–360 m, water temperature
of 10–16 °C, salinity of 34.5–34.7 ppt,
and dissolved oxygen range between
3.0–4.0 ml/l (Cao et al., 2011).
Analysis of Petition and Information
Readily Available in NMFS Files
Below we evaluate the information
provided in the petition and readily
available in our files to determine if the
petition presents substantial scientific
or commercial information indicating
that an endangered or threatened listing
may be warranted as a result of any of
the factors listed under section 4(a)(1) of
the ESA. If requested to list a global
population or, alternatively, a DPS, we
first determine if the petition presents
substantial information that the
petitioned action is warranted for the
global population. If it does, then we
make a positive finding on the petition
and conduct a review of the species
range-wide. If after this review we find
that the species does not warrant listing
range-wide, then we will consider
whether the populations requested by
the petition qualify as DPSs and warrant
listing. If the petition does not present
substantial information that the global
population may warrant listing, but it
has requested that we list any distinct
populations of the species as threatened
or endangered, then we consider
whether the petition provides
substantial information that the
requested population(s) may qualify as
DPSs under the discreteness and
significance criteria of our joint DPS
Policy, and if listing any of those DPSs
may be warranted. We summarize our
analysis and conclusions regarding the
information presented by the petitioners
and in our files on the specific ESA
section 4(a)(1) factors that we find may
be affecting the species’ risk of global
extinction below.
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Feeding Ecology
Bigeye threshers feed on small to
medium sized pelagic fishes (e.g.,
lancetfishes, herring, mackerel and
small billfishes), bottom fishes (e.g.,
hake), and cephalopods (e.g., squids).
Thresher sharks are unique in that they
use their tail in a whip-like fashion to
disorient and incapacitate their prey
prior to consumption (Oliver, 2013).
The arrangement of the eyes, with
keyhole-shaped orbits extending onto
the dorsal surface of the head, suggest
that this species has a dorsal/vertical
binocular field of vision (unlike other
threshers), which may be related to
fixating on prey and striking them with
its tail from below (FAO 2015 species
fact sheet).
Life History
Bigeye thresher sharks have an
estimated lifespan of approximately 20–
21 years and a maximum total length of
about 4.6 m. Maturity in bigeye
threshers occurs at 7–13 years and 275–
300 cm total length (TL) for males and
8–15 years and 290–341cm (TL) for
females. Bigeye threshers have low
reproductive capacity of only 2–4 pups
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Bigeye Thresher Shark Status and
Trends
The petition does not provide a
population abundance estimate for
bigeye thresher sharks, but points to its
‘‘vulnerable’’ status on the IUCN Red
List. The petition asserts that a global
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decline of bigeye thresher sharks has
been caused mainly by commercial and
recreational fishing (both direct harvest
and bycatch), as evidenced by
substantial population declines in every
area where sufficient historical and
current population data exist. In the
Northwest and Western Central
Atlantic, the petition cites an 80 percent
decline in bigeye thresher sharks since
the early 2000s, with an estimated
average overall decline of 63 percent
since the beginning of data collection in
1986. In the Southwest Atlantic, the
petition describes the popularity of
bigeye threshers in the Brazilian Santos
longline fishery, and asserts that some
vessels are directly targeting this species
specifically for its fins. The petition also
describes consistent gradual decreases
in catch per unit effort (CPUE) for this
species in the region. The petition
describes likely declines of bigeye
thresher sharks in the Mediterranean
based on declines of other pelagic shark
species, including congener A. vulpinus,
due to high fishing pressure. In the
Indo-West Pacific, the petition cites the
prevalence of finning activities,
including both legal and extensive
illegal directed shark catch in this
region, and states that the bigeye
thresher in particular is preferentially
retained in certain fisheries. In the
Eastern Central Pacific, the petition cites
83 percent declines in thresher
populations when compared to research
surveys from the 1950s. Finally, the
petition points to increased interest in
recreational fishing of the bigeye
thresher shark, with the potential for
high post-release mortality. The petition
does not provide information on
abundance estimates across the global
range of the species.
The last IUCN assessment of the
bigeye thresher shark was completed in
2009, and several estimates of global
and subpopulation trends and status
have been made and are described in
the following text. In the Northwest
Atlantic, declines in relative abundance
cited by the petitioner were derived
from analyses of logbook data, reported
´
in Baum et al., (2003) and Cortes (2007).
The former study analyzed logbook data
for the U.S. pelagic longline fleets
targeting swordfish and tunas in the
Northwest Atlantic, and reported an 80
percent decline in relative abundance
for thresher sharks (common and bigeye
threshers combined) from 1986 to 2000.
The latter study reported a 63 percent
decline of thresher sharks (at the genus
level) based on logbook data, occurring
´
between 1986 and 2006 (Cortes, 2007).
However, the observer index data from
´
the same study (Cortes, 2007) shows an
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opposite trend in relative abundance,
with a 28 percent increase of threshers
in the Northwest Atlantic since 1992.
Logbook data over the same period
(1992–2006) shows a 50 percent decline
in thresher sharks. The logbook dataset
is the largest available for the western
North Atlantic Ocean, but the observer
dataset is generally more reliable in
terms of consistent identification and
reporting. According to observer data,
relative abundance of thresher sharks
(again, only at the genus level) in the
western North Atlantic Ocean appears
to have stabilized or even be increasing
´
since the late 1990s (Cortes, 2007). A
more recent analysis using logbook data
between 1996 and 2005 provides some
supporting evidence that the abundance
of thresher sharks has potentially
stabilized over this time period (Baum
and Blanchard, 2010). However, it
should be noted that fishing pressure on
thresher sharks began over two decades
prior to the start of this time series; thus,
the estimated declines are not from
virgin biomass. Furthermore, the sample
size in the latter observer analysis was
also very small compared to the
previous logbook analyses, which both
showed declines. Thus, abundance
trend estimates derived from
standardized catch rate indices of the
U.S. pelagic longline fishery suggest that
thresher sharks (both bigeye and
common) have likely undergone a
decline in abundance in this region.
However, the conflicting evidence
between logbook and observer data
showing opposite trends in thresher
shark abundance cannot be fully
resolved at this time. Data are not
available in the petition or in our own
files to assess the trend in population
abundance in this region since 2006, or
to assess the trend specific to the bigeye
thresher shark. Because the logbook data
from this region show consistent
evidence of a significant and continued
decline in thresher sharks, we must
consider this information in our 90-day
determination. Additionally, in the
Southeastern United States, studies
show significant declines in the species,
with decreases in CPUE indicating that
the population of A. superciliosus has
declined by 70 percent from historical
levels (Beerkircher et al., 2002).
For the Northeast Atlantic, there are
no population abundance estimates
available, but data indicate that the
species is taken in driftnets and gillnets.
In the Mediterranean Sea, estimates
show significant declines in thresher
shark abundance during the past two
decades, reflecting data up to 2006.
According to historical data compiled
using a generalized linear model,
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thresher sharks have declined between
96 and 99 percent in abundance and
biomass in the Mediterranean Sea
(Ferretti et al., 2008). Overall, the bigeye
thresher shark has been poorly
documented in the Mediterranean and
is considered scarce or rare.
In the Eastern Central Pacific, logbook
data show a historical decline of
thresher sharks due to pelagic fishing
fleet operations. Trends in abundance
and biomass of thresher sharks in the
eastern tropical Pacific Ocean were
estimated by comparison of pelagic
longline research surveys in the 1950s
with recent data (1990s); these data
were collected by observers on pelagic
longline fishing vessels and
standardized to account for differences
in depth and soak time. This analysis
estimated a decline in combined
thresher abundance of 83 percent and a
decline in biomass to approximately 5
percent of virgin levels (Ward and
Myers, 2005).
In other areas of the world, estimates
of thresher shark abundance are limited.
Bigeye threshers are recorded in the
catches of fisheries operating in the
Indo-West Pacific, but catches of the
species are likely very under-reported.
An analysis of purse seine and longline
observer data from the Western and
Central Pacific produced no clear catch
trends for thresher sharks (Alopias
spp.); however, shark data from observer
data sets are constrained by a lack of
observer coverage, particularly for the
North Pacific, and for the purse seine
fishery by the physical practicalities of
onboard sampling (Clarke, 2011).
Additionally, this study detected a
significant decrease in median size for
thresher sharks in tropical areas, most
likely reflective of trends in bigeye
threshers as they are the most
commonly encountered species in this
region. While catch data are incomplete
and cannot be used to estimate
abundance levels or determine the
magnitude of catches or trends for
bigeye threshers at this time, pelagic
fishing effort in this region is high, with
reported increases in recent years (IUCN
assessment, 2009).
In conclusion, across the species’
global range we find evidence
suggesting that population abundance of
the bigeye thresher shark is declining or,
in the Northwest Atlantic Ocean, may
be stable at a diminished abundance.
While data are still limited with respect
to population size and trends, we find
the petition and our files sufficient in
presenting substantial information on
bigeye thresher shark abundance,
trends, or status to indicate the
petitioned action may be warranted.
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ESA Section 4(a)(1) Factors
The petition indicated three main
categories of threats to the bigeye
thresher shark: overutilization for
commercial, recreational, scientific, or
educational purposes; the inadequacy of
existing regulatory mechanisms; and
other natural or manmade factors
affecting its continued existence. We
discuss each of these below based on
information in the petition, and the
information readily available in our
files.
Overutilization for Commercial,
Recreational, Scientific, or Educational
Purposes
The petition states that ‘‘the bigeye
thresher has shown substantial
population declines in every area where
sufficient historical and current
population data exists’’ and lists four
categories of overutilization: historical,
directed, incidental, and recreational.
The petition describes historical
exploitation as the first category of
overutilization for the species,
predominantly in the Northwest and
Central Atlantic and Eastern Central
Pacific. In the Northwest and Central
Atlantic, bigeye threshers were
historically caught in pelagic longline
fisheries. Bigeye threshers have been a
prohibited species in all commercial
fisheries in the U.S. Atlantic since 2000.
Since these regulations became effective
in 2000, relative abundance of thresher
sharks (again, only at the genus level) in
the western North Atlantic Ocean
appears to have stabilized or even be
increasing since the late 1990s (Baum
´
and Blanchard, 2010; Cortes, 2007).
However, it should be noted that bigeye
threshers are still caught as bycatch and
occasionally landed in the Northwest
Atlantic Ocean despite its prohibited
status (NMFS, 2012; 2013), which may
hinder the ability of the population to
rebound from the historical declines.
As previously mentioned, the petition
also states that logbook data from the
Eastern Central Pacific shows a
historical decline of bigeye thresher
sharks due to pelagic fishing fleet
operations known to take this species.
Trends in abundance and biomass of
thresher sharks in the eastern tropical
Pacific Ocean were estimated by
comparison of pelagic longline research
surveys in the 1950s with recent data
(1990s); these data were collected by
observers on pelagic longline fishing
vessels and standardized to account for
differences in depth and soak time. For
example, in the 1990’s, longliners
deployed more hooks (averaging 2240
hooks per day compared to 322 hooks
in the 1950s) over a wider depth range
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(down to 600 m compared to 200 m) for
longer periods. Thus, while catches of
thresher sharks increased (from 112
threshers in the 1950s survey to 511
threshers in the 1990s survey), this
analysis estimated a decline in
combined thresher abundance of 83
percent, with a decline in mean biomass
to approximately 5 percent of virgin
levels and a decline in mean body mass
from 17 kg to 12 kg). While this analysis
was not species-specific (Ward and
Myers, 2005), we must consider this
information in our 90-day finding given
the potential significant population
decline of bigeye threshers in this
region.
In addition to broad commercial
harvest of the species, the petition states
that direct catch related to the shark fin
trade has resulted in population decline,
and that bigeye thresher sharks are
targeted and preferentially retained for
their fins. For example, the petition
stated in the Indo-West Pacific, a single
thresher fin can fetch US $250, creating
incentives that would drive
overutilization. However, this statement
is not entirely correct. While it is true
that high prices are paid for thresher
sharks, the value of US $250 was not for
a single fin, but rather for the entire
shark (Gilman et al., 2007). Still, in
comparison to other sharks (e.g.,
shortfin mako only fetches US $50 per
shark), thresher sharks appear to be
highly valued and consequently targeted
for both their meat and fins. While the
petition did not provide any
information connecting population
declines as a result of this direct catch,
evidence suggests that the three thresher
shark species, collectively, may account
for approximately 2.3 percent of the fins
auctioned in Hong Kong, the world’s
largest fin-trading center (Clarke, 2006).
This translates to 0.4 million to 3.9
million threshers that may enter the
global fin trade each year (Clarke, 2006),
with bigeye thresher having the highest
value and vulnerability to fishing
compared to the other thresher species
´
(Cortes, 2010); still, the relative
proportion of each thresher shark
species comprising the shark fin trade is
not available in this genus-level
assessment and information on the
species-specific impact of this harvest
on bigeye thresher shark abundance is
not provided by the petitioner.
However, we found species-specific
evidence in our files that bigeye
threshers may be highly utilized in the
shark fin trade. In a genetic barcoding
study of shark fins from markets in
Taiwan, bigeye threshers were one of 20
species identified and comprised 0.07
percent of collected fin samples.
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Additionally, thresher sharks comprised
15 percent of fins genetically tested
from markets throughout Indonesia (the
largest shark catching country in the
world), with bigeye threshers making up
an estimated 7.6 percent of all fins
tested. The high frequency of bigeye
threshers in the markets across
Indonesia provides some evidence that
they are not just caught incidentally, but
are targeted by large-scale fisheries
(Sembiring, 2015). In another genetic
barcoding study of fins from United
Arab Emirates, the fourth largest
exporter in the world of raw dried shark
fins to Hong Kong, the authors found
that the Alopiidae family represented
5.9 percent of the trade from Dubai,
with bigeye thresher comprising 2.31
percent (Jabado et al., 2015). Overall,
evidence that bigeye thresher sharks
(and threshers in general) are highly
valued for their fins, are possibly
targeted in some areas, and comprise a
portion of the Hong Kong fin-trading
auction suggests that this threat may
impact the species.
In the Indian Ocean, the status and
abundance of shark species is poorly
known despite a long history of research
and more than 60 years of commercial
exploitation by large-scale tuna fisheries
(Romanov et al., 2010). Pelagic sharks,
including bigeye threshers, are targeted
in various fisheries, including semiindustrial, artisanal, and recreational
fisheries. Countries that fish for various
pelagic species of sharks include: Egypt,
India, Iran, Oman, Saudi Arabia, Sudan,
United Arab Emirates, and Yemen,
where the probable or actual status of
shark populations is unknown, and
Maldives, Kenya, Mauritius, Seychelles,
South Africa, and United Republic of
Tanzania, where the actual status of
shark populations is presumed to range
from fully exploited to over-exploited
(Young, 2006). In 2013, an Ecological
Risk Assessment (ERA) was developed
by the Indian Ocean Tuna Commission
(IOTC) Scientific Committee to quantify
which shark species are most at risk
from the high levels of pelagic longline
fishing pressure. In this ERA, the IOTC
Scientific Committee noted that A.
superciliosus received a high
vulnerability ranking (No. 2) for
longline gear, as the species is
characterized as one of the least
productive shark species, and is highly
susceptible to catch in longline
fisheries. The ERA also noted that the
available evidence indicates
considerable risk to the status of the
Indian Ocean Alopias spp. stocks at
current catch levels, which, from 2000–
2011 was estimated to be 22,811 mt
(Merua et al., 2013).
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Indirect catch is another category of
overutilization identified by the
petition, which states that post-release
mortality may be high in the species.
However, no information is provided in
the petition to connect the effect of
bycatch on population declines of the
species. In the Northeast Atlantic and
Mediterranean, while there are no target
fisheries for thresher sharks, they are
taken as bycatch in various fisheries,
including the Moroccan driftnet fishery
in the southwest Mediterranean. They
are also caught by industrial and semiindustrial longline fisheries and by
artisanal gillnet fisheries. In our files,
we found evidence that in the last two
decades, thresher sharks (common and
bigeye) have declined between 96 and
99 percent in abundance and biomass in
the Mediterranean Sea (Ferretti, 2008).
Although bigeye thresher sharks have
been a prohibited species in U.S.
Atlantic commercial fisheries since
2000, they are still incidentally taken as
bycatch on pelagic longlines and in
gillnets on the East Coast. For example,
in our files, we found that since the
prohibition on bigeye threshers came
into effect in 2000, approximately 1,493
lbs, dressed weight (677 kg) of bigeye
thresher were landed in the Atlantic
(NMFS, 2012; 2014) despite its
prohibited status. In 2010, the United
States reported that bigeye thresher
represented the second largest amount
of dead discards in the Atlantic
commercial fleet, reporting a total of 46
t (NOAA, 2010 Report to ICCAT). In
2011, this number dropped to 27 t of
bigeye thresher dead discards (NOAA,
2011 Report to ICCAT). Further, several
recent reports assessing the
vulnerability of bigeye threshers and
other pelagic sharks to bycatch in the
U.S. Atlantic pelagic longline fishery
characterized the bigeye thresher as
highly vulnerable (Cortes, 2010; Cortes,
2012; Gallagher et al., 2014). These
landings and dead discards may be
linked to declines in the species across
the Northwest Atlantic portion of its
range; however, as discussed earlier,
conflicting logbook and observer data
decrease the certainty of these trends
´
(Cortes, 2007; Baum and Blanchard,
2010).
In the Southwest Atlantic Ocean, off
the coast of Brazil, bigeye threshers
represent almost 100 percent of thresher
sharks caught in longline fisheries
(Amorin, 1998). The landed catch and
CPUE of bigeye thresher shark in this
fishery increased from 1971 to 1989,
and then gradually decreased from 1990
to 2001; however, this does not
necessarily reflect stock abundance
because changes in the depth of fishing
operations also occurred, which may
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have affected the time series. Thus,
further information is needed to resolve
this. In our files, we found that bigeye
threshers are also taken in Uruguayan
longline fisheries at similar levels. In
one study, observer data from 2001–
2005 recorded a total of 295 A.
superciliosus specimens, in which the
species’ abundance was characterized as
‘‘low’’ despite high fishing effort
(Berrondo et al., 2007). Further,
observer data from 1992–2000 showed
that bigeye threshers experience high
mortality in longline fisheries in the
Southwest Atlantic, with 54 percent
dead upon capture (Beerkircher et al.,
2002). Given the declines reported in
other areas for which data are available
throughout other parts of the species’
range and the high fishing pressure from
fleets throughout the Southwest
Atlantic, A. superciliosus may be
experiencing a level of exploitation in
this part of its range that may increase
its risk of extinction.
In the Eastern Central Pacific, the
petition points to the fact that bigeye
threshers have been recorded as bycatch
in purse seine fleets operating in this
region, in which bigeye threshers
comprised 1 percent of shark species
caught during a Shark Characteristics
Sampling Program conducted from
1994–2004 (Roman-Verdesoto and
¨
Orozco-Zoller, 2005). Bycatch for this
report was defined as sharks that were
discarded dead after being removed
from the net and placed on the vessel.
Since 2010, catches of thresher sharks in
this fishery have fluctuated between 10
t and 14 t; however, in a preliminary
productivity-susceptibility assessment,
bigeye threshers were characterized as
having a low susceptibility to this
fishery (IAATC, 2009). Complete
bycatch and discard data are not readily
available from longline fleets in the
Eastern Pacific. In our files, we found
that bigeye thresher sharks are minor
components of U.S. West Coast
fisheries, taken incidentally and
presumably not overexploited, at least
locally. The bigeye thresher occurs
regularly but in low numbers,
comprising only approximately 9
percent of common thresher catch
(PFMC, 2003). Overall, we found that
apart from blue and silky sharks, there
are no stock assessments available for
shark species in the Eastern Pacific, and
hence the impacts of bycatch on the
population are unknown (IATTC, 2014).
However, despite a lack of information
regarding present levels of bycatch
occurring in other fisheries throughout
the Eastern Pacific, as described earlier,
thresher sharks were estimated to have
experienced an 83 percent decline in
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this part of the species’ range as a result
of fishing mortality in longline fisheries.
Given the high rates of bycatch-related
mortality observed in this species
throughout other parts of its range (e.g.,
Northwest and Southwest Atlantic,
Indian Ocean, and Central Pacific), it is
likely the species experiences similar
rates of bycatch-related mortality in this
part of its range as well. Thus, it is likely
that the historical and continued levels
of exploitation in this part of the
species’ range are impacting the species,
such that listing may be warranted.
We found evidence that bigeye
threshers are known to interact with
longline fisheries throughout the IndoPacific. In the Western and Central
Pacific, where sharks represent 25
percent of the longline fishery catch,
observer data showed that bigeye
thresher shark is the 7th most
commonly bycaught species of shark out
of a total 49 species reported by
observers (Molony, 2007). We found
that bigeye threshers are commonly
taken as bycatch in longline fisheries in
the Republic of the Marshall Islands, in
which they exhibit at-vessel and/or
post-release mortality of 50 percent, and
nearly 99 percent are finned and
subsequently discarded (Bromhead,
2012). Further, in a species status
snapshot for thresher sharks in the
Western and Central Pacific, Clarke et
al., (2011) identified significant
decreasing size trends for thresher
sharks in tropical areas, which may be
indicative of population declines in
these areas. It is thought that these
findings most likely reflect trends of
bigeye threshers as they are the most
common thresher species encountered
in this region, with catches of common
and pelagic threshers characterized as
rare or uncommon. Bigeye threshers are
also commonly caught by Hawaii
longline fisheries, particularly on deepset gear (Walsh et al., 2009), and
represented 4.1 percent of shark catches
from 1995–2006. While catches of
thresher sharks (Alopias spp.) have
trended upward, actual landings of
thresher sharks in Hawaii have
decreased from 50 mt in 2001 to 16 mt
in 2010, presumably due to the
implementation of state and Federal
laws regarding shark finning (NMFS,
2011).
In the Indian Ocean, while fisheries
are directed at other species, bigeye
threshers are commonly caught as
bycatch and catch rates are considered
high (IOTC, 2011; Hererra and Pierre,
2011). For example, bycatch of bigeye
threshers has been recorded in Japanese
and Taiwanese longline fisheries.
According to Japanese observer data,
162 bigeye threshers were bycaught in 6
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months (from July 2010 to January
2011). These data do not include livereleased bigeye thresher sharks (Ardill
et al., 2011), which reportedly have high
post-release mortality rates (IOTC,
2014). Observer data from Taiwanese
longline fleets (with coverage ranging
from only 2.2 percent in 2004 to 20.8
percent in 2007) recorded a total of 445
bigeye threshers bycaught from 2004–
2008, with approximately 61 percent
discarded (Huang and Liu, 2010).
Hooking mortality is apparently very
high in this region; therefore, the IOTC’s
regulation 10/12 that prohibits the
onboard retention of any part of any
thresher species and promotes live
release of thresher sharks may be
ineffective for the conservation of bigeye
thresher sharks. For example, in the
Portuguese longline fleet, bigeye
threshers experienced a high rate of atvessel mortality of 68.4 percent (n = 19)
from May to September 2011 (Ardill et
al., 2011). The IOTC reported in 2014
that ‘‘maintaining or increasing effort in
this region will probably result in
further declines in biomass,
productivity and CPUE’’ for bigeye
threshers (IOTC, 2014).
Overall, there is considerable
uncertainty regarding the actual levels
of bycatch of bigeye thresher shark
occurring throughout its range;
however, it is likely that these rates are
significantly under-reported due to a
lack of comprehensive observer
coverage in areas of its range in which
the highest fishing pressure occurs, as
well as a tendency for fishers to not
record discards in fishery logbooks.
Nevertheless, given the prevalence of
bigeye threshers as incidental catch
throughout its range and the species’
observed high hooking and post-release
mortality rates, combined with the
species’ low productivity, bycatchrelated fishing mortality may be a threat
placing the species at an increased risk
of extinction.
The petition identified recreational
fishing as the fourth category of
overutilization. In our files, we found
evidence that thresher sharks,
particularly common threshers, are
valued by recreational sport fishermen
throughout the species’ U.S. East Coast
and West Coast range; however, bigeye
threshers do not appear to be as
important in recreational fisheries and
are largely prohibited in many fisheries
within the United States. The petition
described results from Heberer (2010),
which identified the potential negative
impact of recreational fishing on the
survival of congener, A. vulpinus, by
assessing post-release survivorship of
sharks captured using the caudal finbased techniques used by most
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recreational fishermen in southern
California. As previously described,
thresher sharks use their elongate upper
caudal lobe to immobilize prey before it
is consumed, and the majority of
common thresher sharks captured in the
southern California recreational fishery
are hooked in the caudal fin and hauledin backwards. This is significant
because common threshers are obligate
ram ventilators that require forward
motion to ventilate the gills (Heberer,
2010), and the reduced ability to extract
oxygen from the water during capture,
as well as the stress induced from these
capture methods, may influence
recovery following release. The findings
of Heberer (2010) demonstrate that large
tail-hooked common thresher sharks
with prolonged fight times (≥85 min)
exhibit a heightened stress response,
which may contribute to an increased
mortality rate. This work suggests,
especially for larger thresher sharks, that
recreational catch-and-release may not
be an effective conservation-based
strategy for the species. A recent paper
by Sepulveda (2014) found similar
evidence for high post-release mortality
of recreationally caught common
thresher sharks in the California
recreational shark fishery. Their results
demonstrated that caudal fin-based
angling techniques, which often result
in trailing gear left embedded in the
shark, can negatively affect post-release
survivorship. This work suggests that
mouth-based angling techniques can,
when performed properly, result in a
higher survivorship of released sharks.
The petition argues that because
common thresher sharks may exhibit
high mortality in recreational fisheries
that bigeye threshers would likely
exhibit similar results. While this may
be true, in our files, we found no
evidence to suggest that bigeye threshers
are declining (or responding in a
negative fashion) as a result of
utilization by recreational fisheries.
While it is not known if this species
enters the California recreational fishery
on any regular basis, presumably only
few are taken. Further, there are no
records from the recreational fishery off
Oregon or Washington (NMFS, 2007),
and in fact, fishing of all thresher
species is prohibited in Washington.
Likewise, in the Northwest Atlantic,
bigeye threshers have been prohibited in
recreational fisheries by Federal
regulations since 1999. Further, U.S.
states from Maine to Florida have
adopted the Interstate Fisheries
Management Plan (FMP) for Atlantic
Coastal Sharks adopted by the Atlantic
States Marine Fisheries Commission
(ASMFC), which prohibits recreational
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fishing of bigeye threshers. Finally,
since prohibition of this species was
implemented in 1999, there has been no
observed recreational harvest of this
species, with the exception of years
2002 and 2006 (NMFS, 2014). The
petition did not provide, nor could we
find in our files, any information
regarding the threat of recreational
fishing to bigeye threshers throughout
the rest of the species’ range. Thus, we
find that the information presented in
the petition, and in our files, does not
comprise substantial information that
would lead us to conclude the species
may have an increased risk of extinction
from overutilization as a result of
recreational fishing activities.
Overall, trends in the North West and
Central Atlantic Ocean suggest that the
species experienced historical declines
from overexploitation, but may be
stabilized and possibly increasing in
recent years, although there is
considerable uncertainty regarding these
trends. Elsewhere across the species’
range, information in the petition and in
our files suggests that the species may
continue to experience declines as a
result of overutilization from both direct
and indirect fishing pressure. In
summary, the petition, references cited,
and information in our files comprise
substantial information indicating that
listing may be warranted because of
overutilization for commercial
purposes.
Inadequacy of Existing Regulatory
Mechanisms
The petition points to ‘‘virtually nonexistent international regulatory
protections’’ to assert that bigeye
threshers qualify for listing due to the
inadequacy of existing regulatory
mechanisms. For example, the petition
mentions the lack of protections from
the Convention on International Trade
of Endangered Species (CITES) for the
bigeye thresher shark, but then states
that even if the species was listed under
CITES, it would still be inadequate due
to the fact that a CITES listing would
only address threats associated with the
international trade of the species, and
would not address such impacts as
bycatch. Although a CITES Appendix II
listing or international reporting
requirements would provide better data
on the global catch and trade of the
bigeye thresher shark, the lack of a
CITES listing or requirements does not
suggest that current regulatory
mechanisms are inadequate to protect
the bigeye thresher shark population
from becoming threatened or
endangered under the ESA. The petition
also asserts that the recent listing of
bigeye thresher shark under Appendix II
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of the Convention of Migratory Species
(CMS) is also inadequate given that the
United States and other range states are
not Member Parties to CMS and are
therefore not bound by the requirements
imposed by the Appendix II listing. The
petition further states that the
Convention text is only suggestive and
not self-executing upon the listing of a
species. On the contrary, we find that a
CMS Appendix II listing now
encourages international cooperation
towards conservation of the species, and
although the United States is not
currently a party to CMS, the United
States is a signatory to a number of CMS
instruments for the conservation of
various marine species, including
sharks.
The petition also asserts that finning
regulations and species-specific
retention bans are ‘‘inadequate’’ for
protecting the bigeye thresher shark
species because they may still be
caught, either directly or indirectly. The
petition also cites several regional
fisheries management organizations
(RFMOs) that implement a 5 percent finto-carcass ratio regulation, describes
what the petitioner contends are
potential loopholes in those regulations,
and states that these general regulations
are inadequate for the bigeye thresher
shark, whose larger fins make it a more
targeted species. The petition further
contends that species-specific retention
bans for bigeye threshers, such as the
ones implemented by ICCAT and IOTC
that specifically prohibit the retention,
transshipping, landing, storing, selling,
or offering for sale any part or whole
carcass of bigeye thresher sharks, are
also inadequate largely because they do
not address incidental catch and
subsequent high mortality rates of the
species. Based on the information
presented in the petition and in our
files, we find that the bigeye thresher
shark is highly valued for its fins, and
can be identified in the shark fin market
at the species level. While regulations
banning the finning of sharks are a
common form of shark management and
have been adopted by far more countries
and regional fishery management
organizations than the petition lists (see
HSI, 2012), we agree with the petition
that due to high rates of hooking
mortality observed in this species as a
result of incidental catch, prohibitions
on the retention of bigeye thresher or
restrictions on the finning of sharks may
not be adequate to protect the bigeye
thresher from fishing mortality rates that
may contribute to its extinction risk,
especially given the species’
significantly low productivity and
intrinsic rate of population increase.
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In addition to the inadequacy of
international regulations, the petition
states that ‘‘while the U.S. has
attempted to protect the bigeye thresher
shark in U.S. waters, piecemeal
protections that fail to cover the species
throughout its migratory range have
proven to be unsuccessful.’’ Though
U.S. regulations by their jurisdictional
nature only cover U.S. fishers, we do
not agree that this makes them
inadequate. We find that U.S. national
fishing regulations include numerous
regulatory mechanisms for both sharks
in general, and bigeye threshers
specifically, that may help protect the
species. For example, in the U.S.
Atlantic, the bigeye thresher has been a
prohibited species in both commercial
and recreational fisheries since 2000
and 1999, respectively, under the 1999
Fishery Management Plan for Atlantic
Tunas, Swordfish, and Sharks. In
addition, current management measures
for the Atlantic shark fisheries include
the following: commercial quotas,
commercial retention limits, limited
entry, time-area closures, and
recreational bag limits. Sharks are
required to be landed with fins naturally
attached to the carcass. Additionally,
several U.S. states have prohibited the
sale or trade of shark fins/products as
well, including Hawaii, Oregon,
Washington, California, Illinois,
Maryland, Delaware, New York, and
Massachusetts, subsequently decreasing
the United States’ contribution to the fin
trade. For example, after the state of
Hawaii prohibited finning in its waters
in 2000 and required shark fins to be
landed with their corresponding
carcasses in the state, shark fin imports
from the United States into Hong Kong
declined significantly (54 percent
decrease, from 374 to 171 tonnes), as
Hawaii could no longer be used as a fin
trading center for the international
fisheries operating and finning in the
Central Pacific (Miller, 2014). Except for
smooth dogfish (Mustelus canis), the
U.S. Shark Conservation Act of 2010
protects all shark species, making it
illegal to remove any of the fins of a
shark (including the tail) at sea; to have
custody, control, or possession of any
such fin aboard a fishing vessel unless
it is naturally attached to the
corresponding carcass; to transfer any
such fin from one vessel to another
vessel at sea, or to receive any such fin
in such transfer, without the fin
naturally attached to the corresponding
carcass; or to land any such fin that is
not naturally attached to the
corresponding carcass, or to land any
shark carcass without such fins
naturally attached. However, we do
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agree with the petition that these
regulations do not address the issue of
bycatch-related mortality of the species,
especially considering the fact that
bigeye threshers are still bycaught in
U.S. fisheries.
Overall, while measures may be
implemented to reduce bycatch, we
found no evidence that these measures
have been incorporated into common
practice throughout the species’ range,
particularly in areas where fishing
pressure is most concentrated. Further,
while numerous finning and speciesspecific retention bans have been
implemented, these regulations fail to
address the species’ high rate of
bycatch-related mortality. In summary,
the petition, references cited, and
information in our files comprise
substantial information indicating that
the species may be impacted by the
inadequacy of regulatory mechanisms in
parts of its range, such that listing may
be warranted.
Other Natural or Manmade Factors
Affecting Its Existence
The petition states that the biological
constraints of the bigeye thresher shark,
such as its low reproduction rate
(typically 2–4 pups a year), coupled
with a late age of maturity
(approximately 12–14 years for females,
and slightly earlier for males, between
9–10 years) contribute to the species’
vulnerability to harvesting and its
inability to recover rapidly. We agree
with the petition that the bigeye
thresher shark exhibits relatively slow
growth rates and low fecundity. An
ecological risk assessment conducted to
inform the International Commission for
the Conservation of Atlantic Tunas
(ICCAT) categorized the relative risk of
overexploitation of the 11 major species
of pelagic sharks, including the bigeye
´
thresher shark (Cortes et al., 2010,
2012). The study derived an overall
vulnerability ranking for each of the 11
species, which was defined as ‘‘a
measure of the extent to which the
impact of a fishery [Atlantic longline]
on a species will exceed its biological
´
ability to renew itself’’ (Cortes et al.,
2010, 2012). This robust assessment
found that bigeye thresher sharks have
a combination of low productivity and
high susceptibility to pelagic longline
gear, which places the bigeye thresher at
high risk of overexploitation to the
combined pelagic longline fisheries in
´
the Atlantic Ocean (Cortes et al., 2010,
2012). In fact, of the 11 species
examined in this study, Atlantic bigeye
thresher sharks were identified as one of
the most vulnerable and least
productive shark species. Even within
the genus Alopias, the bigeye thresher
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Fmt 4702
Sfmt 4702
shark has the slowest population growth
rate of all thresher sharks, with an
exceptionally low potential annual rate
of population increase (0.002–0.009 or
1.6 percent) under sustainable
´
exploitation (Cortes, 2008; Dulvy et al.,
2008; Smith et al., 2008). This makes
them particularly vulnerable to any
level of fisheries exploitation, whether
targeted or caught as bycatch in fisheries
for other species. Given that bigeye
thresher sharks are caught regularly as
incidental bycatch throughout its range
and experience high mortality rates as a
result, and that the species may be
targeted in some areas for its fins, the
species’ growth and reproductive factors
may inhibit the species’ ability to
recover from even moderate levels of
exploitation, thus placing the bigeye
thresher shark at an increased risk of
extinction as a result. In summary, the
petition, references cited, and
information in our files comprise
substantial information indicating that
the species is impacted by ‘‘other
natural or manmade factors,’’ including
the life history trait of slow
productivity, such that listing the
species may be warranted.
Summary of Section 4(a)(1) Factors
We conclude that the petition does
not present substantial scientific or
commercial information indicating that
the ESA section (4)(a)(1) threats of
‘‘present or threatened destruction,
modification, or curtailment of its
habitat or range’’ or ‘‘disease or
predation’’ may be causing or
contributing to an increased risk of
extinction for the global population of
the bigeye thresher shark. However, we
do conclude that the petition and
information in our files present
substantial scientific or commercial
information indicating that the section
4(a)(1) factor ‘‘overutilization for
commercial, recreational, scientific, or
educational purposes,’’ as well as
‘‘inadequacy of existing regulatory
mechanisms’’ and ‘‘other manmade or
natural factors,’’ may be causing or
contributing to an increased risk of
extinction for the species.
Petition Finding
Based on the above information and
the criteria specified in 50 CFR
424.14(b)(2), we find that the petition
and information readily available in our
files present substantial scientific and
commercial information indicating that
the petitioned action of listing the
bigeye thresher shark worldwide as
threatened or endangered may be
warranted. Therefore, in accordance
with section 4(b)(3)(A) of the ESA and
NMFS’ implementing regulations (50
E:\FR\FM\11AUP1.SGM
11AUP1
Federal Register / Vol. 80, No. 154 / Tuesday, August 11, 2015 / Proposed Rules
CFR 424.14(b)(3)), we will commence a
status review of the species. During the
status review, we will determine
whether the species is in danger of
extinction (endangered) or likely to
become so within the foreseeable future
(threatened) throughout all or a
significant portion of its range. We now
initiate this review, and thus, we
consider the bigeye thresher shark to be
a candidate species (69 FR 19975; April
15, 2004). Within 12 months of the
receipt of the petition (April 27, 2016),
we will make a finding as to whether
listing the species as endangered or
threatened is warranted as required by
section 4(b)(3)(B) of the ESA. If listing
the species is found to be warranted, we
will publish a proposed rule and solicit
public comments before developing and
publishing a final rule.
rmajette on DSK2TPTVN1PROD with PROPOSALS
Information Solicited
To ensure that the status review is
based on the best available scientific
and commercial data, we are soliciting
VerDate Sep<11>2014
14:44 Aug 10, 2015
Jkt 235001
information relevant to whether the
bigeye thresher shark is endangered or
threatened. Specifically, we are
soliciting information in the following
areas: (1) Historical and current
distribution and abundance of this
species throughout its range; (2)
historical and current population
trends; (3) life history in marine
environments, including identified
nursery grounds; (4) historical and
current data on bigeye thresher shark
bycatch and retention in industrial,
commercial, artisanal, and recreational
fisheries worldwide; (5) historical and
current data on bigeye thresher shark
discards in global fisheries; (6) data on
the trade of bigeye thresher shark
products, including fins, jaws, meat,
and teeth; (7) any current or planned
activities that may adversely impact the
species; (8) ongoing or planned efforts to
protect and restore the species and its
habitats; (9) population structure
information, such as genetics data; and
(10) management, regulatory, and
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48069
enforcement information. We request
that all information be accompanied by:
(1) Supporting documentation such as
maps, bibliographic references, or
reprints of pertinent publications; and
(2) the submitter’s name, address, and
any association, institution, or business
that the person represents.
References Cited
A complete list of references is
available upon request to the Office of
Protected Resources (see ADDRESSES).
Authority
The authority for this action is the
Endangered Species Act of 1973, as
amended (16 U.S.C. 1531 et seq.).
Dated: August 5, 2015.
Samuel D. Rauch III,
Deputy Assistant Administrator for
Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2015–19551 Filed 8–10–15; 8:45 am]
BILLING CODE 3510–22–P
E:\FR\FM\11AUP1.SGM
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Agencies
[Federal Register Volume 80, Number 154 (Tuesday, August 11, 2015)]
[Proposed Rules]
[Pages 48061-48069]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-19551]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Parts 223 and 224
[Docket No. 150506426-5426-01]
RIN 0648-XD942
Endangered and Threatened Wildlife; 90-day Finding on a Petition
To List the Bigeye Thresher Shark as Threatened or Endangered Under the
Endangered Species Act
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: 90-day petition finding, request for information, and
initiation of status review.
-----------------------------------------------------------------------
SUMMARY: We, NMFS, announce the 90-day finding on a petition to list
the bigeye thresher shark (Alopias superciliosus) range-wide, or in the
alternative, as one or more distinct population segments (DPSs)
identified by the petitioners as endangered or threatened under the
U.S. Endangered Species Act (ESA). We find that the petition presents
substantial scientific or commercial information indicating that the
petitioned action may be warranted for the species worldwide.
Accordingly, we will initiate a status review of bigeye thresher shark
range-wide at this time. To ensure that the status review is
comprehensive, we are soliciting scientific and commercial information
regarding this species.
DATES: Information and comments on the subject action must be received
by October 13, 2015.
ADDRESSES: You may submit comments, information, or data, identified by
``NOAA-NMFS-2015-0089'' by any one of the following methods:
Electronic Submissions: Submit all electronic public
comments via the Federal eRulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2015-0089. Click the ``Comment Now'' icon,
complete the required fields, and enter or attach your comments.
Mail or hand-delivery: Office of Protected Resources,
NMFS, 1315 East-West Highway, Silver Spring, MD 20910.
Instructions: You must submit comments by one of the above methods
to ensure that we receive, document, and consider them. Comments sent
by any other method, to any other address or individual, or received
after the end of the comment period, may not be considered. All
comments received are a part of the public record and will generally be
posted for public viewing on https://www.regulations.gov without change.
All personal identifying information (e.g., name, address, etc.),
confidential business information, or otherwise sensitive information
submitted voluntarily by the sender will be publicly accessible. We
will accept anonymous comments (enter ``N/A'' in the required fields if
you wish to remain anonymous). Attachments to electronic comments will
be accepted in Microsoft Word, Excel, or Adobe PDF file formats only
FOR FURTHER INFORMATION CONTACT: Chelsey Young, NMFS, Office of
Protected Resources (301) 427-8491.
SUPPLEMENTARY INFORMATION:
Background
On April 27, 2015, we received a petition from Defenders of
Wildlife requesting that we list the bigeye thresher shark (Alopias
superciliosus) as endangered or threatened under the ESA, or, in the
alternative, to list one or more distinct population segments (DPSs),
should we find they exist, as threatened or endangered under the ESA.
Defenders of Wildlife also requested that critical habitat be
designated for this species in U.S. waters concurrent with final ESA
listing. The petition states that the bigeye thresher shark merits
listing as an endangered or threatened species under the ESA because of
the following: (1) The species faces threats from historical and
continued fishing for both commercial and recreational purposes; (2)
life history characteristics and limited ability to recover from
fishing pressure make the species particularly vulnerable to
overexploitation; and (3) regulations are inadequate to protect the
bigeye thresher shark.
ESA Statutory Provisions and Policy Considerations
Section 4(b)(3)(A) of the ESA of 1973, as amended (U.S.C. 1531 et
seq.), requires, to the maximum extent practicable, that within 90 days
of receipt of a petition to list a species as threatened or endangered,
the Secretary of Commerce make a finding on whether that petition
presents substantial scientific or commercial information indicating
that the petitioned action may be warranted, and promptly publish the
finding in the Federal Register (16 U.S.C. 1533(b)(3)(A)). When we find
that substantial scientific or commercial information in a petition and
in our files indicates the petitioned action may be warranted (a
``positive 90-day finding''), we are required to promptly commence a
review of the status of the species concerned, which includes
conducting a comprehensive review of the best available scientific and
commercial information. Within 12 months of receiving the petition, we
must conclude the review with a finding as to whether, in fact, the
petitioned action is warranted. Because the finding at the 12-month
stage is based on a significantly more thorough review of the available
information, a ``may be warranted'' finding at the 90-day stage does
not prejudge the outcome of the status review.
Under the ESA, a listing determination may address a ``species,''
which is defined to also include subspecies and, for any vertebrate
species, any DPS that interbreeds when mature (16 U.S.C. 1532(16)). A
joint NMFS-U.S. Fish and Wildlife Service (USFWS) policy clarifies the
agencies' interpretation of the phrase ``distinct population segment''
for the purposes of listing, delisting, and reclassifying a species
under the ESA (``DPS Policy''; 61 FR 4722; February 7, 1996). A
species, subspecies, or DPS is ``endangered'' if it is in danger of
extinction throughout all or a significant portion of its range, and
``threatened'' if it is likely to become endangered within the
foreseeable future throughout all or a significant portion of its range
(ESA sections 3(6) and 3(20), respectively; 16 U.S.C. 1532(6) and
(20)). Pursuant to the ESA and our implementing regulations, the
determination of whether a species is threatened or endangered shall be
based on any one or a combination of the following five section 4(a)(1)
factors: The present or threatened destruction, modification, or
curtailment of habitat or range; overutilization for commercial,
recreational, scientific, or educational purposes; disease or
predation; inadequacy of existing regulatory mechanisms; and any other
natural or manmade factors affecting the species' existence (16 U.S.C.
1533(a)(1), 50 CFR 424.11(c)).
ESA-implementing regulations issued jointly by NMFS and USFWS (50
CFR 424.14(b)) define ``substantial information'' in the context of
reviewing a petition to list, delist, or reclassify a species as the
amount of information that would lead a reasonable person to
[[Page 48062]]
believe that the measure proposed in the petition may be warranted.
When evaluating whether substantial information is contained in a
petition, we must consider whether the petition: (1) Clearly indicates
the administrative measure recommended and gives the scientific and any
common name of the species involved; (2) contains detailed narrative
justification for the recommended measure, describing, based on
available information, past and present numbers and distribution of the
species involved and any threats faced by the species; (3) provides
information regarding the status of the species over all or a
significant portion of its range; and (4) is accompanied by the
appropriate supporting documentation in the form of bibliographic
references, reprints of pertinent publications, copies of reports or
letters from authorities, and maps (50 CFR 424.14(b)(2)).
At the 90-day stage, we evaluate the petitioner's request based
upon the information in the petition, including its references, and the
information readily available in our files. We do not conduct
additional research, and we do not solicit information from parties
outside the agency to help us in evaluating the petition. We will
accept the petitioner's sources and characterizations of the
information presented, if they appear to be based on accepted
scientific principles, unless we have specific information in our files
that indicates the petition's information is incorrect, unreliable,
obsolete, or otherwise irrelevant to the requested action. Information
that is susceptible to more than one interpretation or that is
contradicted by other available information will not be dismissed at
the 90-day finding stage, so long as it is reliable and a reasonable
person would conclude that it supports the petitioner's assertions.
Conclusive information indicating the species may meet the ESA's
requirements for listing is not required to make a positive 90-day
finding. We will not conclude that a lack of specific information alone
negates a positive 90-day finding, if a reasonable person would
conclude that the unknown information itself suggests an extinction
risk of concern for the species at issue.
To make a 90-day finding on a petition to list a species, we
evaluate whether the petition presents substantial scientific or
commercial information indicating the subject species may be either
threatened or endangered, as defined by the ESA. First, we evaluate
whether the information presented in the petition, along with the
information readily available in our files, indicates that the
petitioned entity constitutes a ``species'' eligible for listing under
the ESA. Next, we evaluate whether the information indicates that the
species at issue faces extinction risk that is cause for concern; this
may be indicated in information expressly discussing the species'
status and trends, or in information describing impacts and threats to
the species. We evaluate any information on specific demographic
factors pertinent to evaluating extinction risk for the species at
issue (e.g., population abundance and trends, productivity, spatial
structure, age structure, sex ratio, diversity, current and historical
range, habitat integrity or fragmentation), and the potential
contribution of identified demographic risks to extinction risk for the
species. We then evaluate the potential links between these demographic
risks and the causative impacts and threats identified in ESA section
4(a)(1).
Information presented on impacts or threats should be specific to
the species and should reasonably suggest that one or more of these
factors may be operative threats that act or have acted on the species
to the point that it may warrant protection under the ESA. Broad
statements about generalized threats to the species, or identification
of factors that could negatively impact a species, do not constitute
substantial information that listing may be warranted. We look for
information indicating that not only is the particular species exposed
to a factor, but that the species may be responding in a negative
fashion; then we assess the potential significance of that negative
response.
Many petitions identify risk classifications made by non-
governmental organizations, such as the International Union for the
Conservation of Nature (IUCN), the American Fisheries Society, or
NatureServe, as evidence of extinction risk for a species. Risk
classifications by other organizations or made under other Federal or
state statutes may be informative, but such classification alone may
not provide the rationale for a positive 90-day finding under the ESA.
For example, as explained by NatureServe, their assessments of a
species' conservation status do ``not constitute a recommendation by
NatureServe for listing under the U.S. Endangered Species Act'' because
NatureServe assessments ``have different criteria, evidence
requirements, purposes and taxonomic coverage than government lists of
endangered and threatened species, and therefore these two types of
lists should not be expected to coincide'' (https://www.natureserve.org/prodServices/pdf/NatureServeStatusAssessmentsListing-Dec%202008.pdf).
Thus, when a petition cites such classifications, we will evaluate the
source of information that the classification is based upon in light of
the standards on extinction risk and impacts or threats discussed
above.
Species Description
Distribution
The bigeye thresher shark (Alopias superciliosus) is a large,
highly migratory oceanic and coastal species of shark found throughout
the world in tropical and temperate seas. In the Western Atlantic
(including the Gulf of Mexico), bigeye threshers can be found off the
Atlantic coast of the United States (from New York to Florida), and in
the Gulf of Mexico off Florida, Mississippi and Texas. They can also be
found in Mexico (from Veracruz to Yucatan), Bahamas, Cuba, Venezuela,
as well as central and southern Brazil. In the Eastern Atlantic, bigeye
threshers are found from Portugal to the Western Cape of South Africa,
including the western and central Mediterranean Sea. In the Indian
Ocean, bigeye threshers are found in South Africa (Eastern Cape and
KwaZulu-Natal), Madagascar, Arabian Sea (Somalia), Gulf of Aden,
Maldives, and Sri Lanka. In the Pacific Ocean, from West to East,
bigeye threshers are known from southern Japan (including Okinawa),
Taiwan (Province of China), Vietnam, between the Northern Mariana
Islands and Wake Island, down to the northwestern coast of Australia
and New Zealand. Moving to the Central Pacific, bigeye threshers are
known from the area between Wake, Marshall, Howland and Baker, Palmyra,
Johnston, Hawaiian Islands, Line Islands, and between Marquesas and
Galapagos Islands. Finally, in the Eastern Pacific, bigeye threshers
occur from Canada to Mexico (Gulf of California) and west of Galapagos
Islands (Ecuador). They are also possibly found off Peru and northern
Chile (Compagno, 2001).
Physical Characteristics
The bigeye thresher shark possesses an elongated upper caudal lobe
almost equal to its body length, which is unique to the Alopiidae
family. It has a broad head, a moderately long and bulbous snout,
curved yet broad-tipped pectoral fins, distinctive grooves on the head
above the gills, and large teeth. The first dorsal fin mid base is
closer to the pelvic-fin bases than to the pectoral-fin bases. The
caudal tip is broad with a wide terminal lobe. While some of the above
characteristics may be shared by
[[Page 48063]]
other thresher shark species, diagnostic features separating this
species from the other two thresher shark species (common thresher, A.
vulpinus, and pelagic thresher, A. pelagicus) are their extremely large
eyes, which extend onto the dorsal surface of the head, and the
prominent notches that run dorso-lateral from behind the eyes to behind
the gills. The body can be purplish grey or grey-brown on the upper
surface and sides, with grey to white coloring on its underside (light
color of abdomen does not extend over pectoral fin bases like common
thresher) and no white dot on upper pectoral fin tips like those often
seen in common threshers (Compagno 2001).
Habitat
Bigeye thresher sharks are found in a diverse spectrum of
locations, including coastal waters over continental shelves, on the
high seas in the epipelagic zone far from land, in deep waters near the
bottom on continental slopes, and sometimes in shallow inshore waters.
They are an epipelagic, neritic, and epibenthic shark, ranging from the
surface and in the intertidal to at least 500 m deep, but mostly below
100 m depth. In our files, we found information indicating that bigeye
threshers prefer an optimum swimming depth of 240-360 m, water
temperature of 10-16 [deg]C, salinity of 34.5-34.7 ppt, and dissolved
oxygen range between 3.0-4.0 ml/l (Cao et al., 2011).
Feeding Ecology
Bigeye threshers feed on small to medium sized pelagic fishes
(e.g., lancetfishes, herring, mackerel and small billfishes), bottom
fishes (e.g., hake), and cephalopods (e.g., squids). Thresher sharks
are unique in that they use their tail in a whip-like fashion to
disorient and incapacitate their prey prior to consumption (Oliver,
2013). The arrangement of the eyes, with keyhole-shaped orbits
extending onto the dorsal surface of the head, suggest that this
species has a dorsal/vertical binocular field of vision (unlike other
threshers), which may be related to fixating on prey and striking them
with its tail from below (FAO 2015 species fact sheet).
Life History
Bigeye thresher sharks have an estimated lifespan of approximately
20-21 years and a maximum total length of about 4.6 m. Maturity in
bigeye threshers occurs at 7-13 years and 275-300 cm total length (TL)
for males and 8-15 years and 290-341cm (TL) for females. Bigeye
threshers have low reproductive capacity of only 2-4 pups per litter
(Chen et al., 1997; Compagno, 2001; Moreno and Mor[oacute]n, 1992) and
a long gestation period of 12 months, although this remains uncertain
due to a lack of birthing seasonality data (Liu et al., 1998). They
(like all thresher sharks) are ovoviviparous and oophagous (developing
embryo in uteri eat unfertilized eggs produced by the ovary). Size at
birth for the bigeye thresher ranges from 64-106 cm TL (Gilmore, 1993),
but a mating season has not yet been identified. Bigeye threshers have
the slowest population growth rate of all thresher sharks, with an
exceptionally low potential annual rate of population increase (0.02;
IUCN; [lambda]=1.009 yr-1, Cort[eacute]s, 2009).
Analysis of Petition and Information Readily Available in NMFS Files
Below we evaluate the information provided in the petition and
readily available in our files to determine if the petition presents
substantial scientific or commercial information indicating that an
endangered or threatened listing may be warranted as a result of any of
the factors listed under section 4(a)(1) of the ESA. If requested to
list a global population or, alternatively, a DPS, we first determine
if the petition presents substantial information that the petitioned
action is warranted for the global population. If it does, then we make
a positive finding on the petition and conduct a review of the species
range-wide. If after this review we find that the species does not
warrant listing range-wide, then we will consider whether the
populations requested by the petition qualify as DPSs and warrant
listing. If the petition does not present substantial information that
the global population may warrant listing, but it has requested that we
list any distinct populations of the species as threatened or
endangered, then we consider whether the petition provides substantial
information that the requested population(s) may qualify as DPSs under
the discreteness and significance criteria of our joint DPS Policy, and
if listing any of those DPSs may be warranted. We summarize our
analysis and conclusions regarding the information presented by the
petitioners and in our files on the specific ESA section 4(a)(1)
factors that we find may be affecting the species' risk of global
extinction below.
Bigeye Thresher Shark Status and Trends
The petition does not provide a population abundance estimate for
bigeye thresher sharks, but points to its ``vulnerable'' status on the
IUCN Red List. The petition asserts that a global decline of bigeye
thresher sharks has been caused mainly by commercial and recreational
fishing (both direct harvest and bycatch), as evidenced by substantial
population declines in every area where sufficient historical and
current population data exist. In the Northwest and Western Central
Atlantic, the petition cites an 80 percent decline in bigeye thresher
sharks since the early 2000s, with an estimated average overall decline
of 63 percent since the beginning of data collection in 1986. In the
Southwest Atlantic, the petition describes the popularity of bigeye
threshers in the Brazilian Santos longline fishery, and asserts that
some vessels are directly targeting this species specifically for its
fins. The petition also describes consistent gradual decreases in catch
per unit effort (CPUE) for this species in the region. The petition
describes likely declines of bigeye thresher sharks in the
Mediterranean based on declines of other pelagic shark species,
including congener A. vulpinus, due to high fishing pressure. In the
Indo-West Pacific, the petition cites the prevalence of finning
activities, including both legal and extensive illegal directed shark
catch in this region, and states that the bigeye thresher in particular
is preferentially retained in certain fisheries. In the Eastern Central
Pacific, the petition cites 83 percent declines in thresher populations
when compared to research surveys from the 1950s. Finally, the petition
points to increased interest in recreational fishing of the bigeye
thresher shark, with the potential for high post-release mortality. The
petition does not provide information on abundance estimates across the
global range of the species.
The last IUCN assessment of the bigeye thresher shark was completed
in 2009, and several estimates of global and subpopulation trends and
status have been made and are described in the following text. In the
Northwest Atlantic, declines in relative abundance cited by the
petitioner were derived from analyses of logbook data, reported in Baum
et al., (2003) and Cort[eacute]s (2007). The former study analyzed
logbook data for the U.S. pelagic longline fleets targeting swordfish
and tunas in the Northwest Atlantic, and reported an 80 percent decline
in relative abundance for thresher sharks (common and bigeye threshers
combined) from 1986 to 2000. The latter study reported a 63 percent
decline of thresher sharks (at the genus level) based on logbook data,
occurring between 1986 and 2006 (Cort[eacute]s, 2007). However, the
observer index data from the same study (Cort[eacute]s, 2007) shows an
[[Page 48064]]
opposite trend in relative abundance, with a 28 percent increase of
threshers in the Northwest Atlantic since 1992. Logbook data over the
same period (1992-2006) shows a 50 percent decline in thresher sharks.
The logbook dataset is the largest available for the western North
Atlantic Ocean, but the observer dataset is generally more reliable in
terms of consistent identification and reporting. According to observer
data, relative abundance of thresher sharks (again, only at the genus
level) in the western North Atlantic Ocean appears to have stabilized
or even be increasing since the late 1990s (Cort[eacute]s, 2007). A
more recent analysis using logbook data between 1996 and 2005 provides
some supporting evidence that the abundance of thresher sharks has
potentially stabilized over this time period (Baum and Blanchard,
2010). However, it should be noted that fishing pressure on thresher
sharks began over two decades prior to the start of this time series;
thus, the estimated declines are not from virgin biomass. Furthermore,
the sample size in the latter observer analysis was also very small
compared to the previous logbook analyses, which both showed declines.
Thus, abundance trend estimates derived from standardized catch rate
indices of the U.S. pelagic longline fishery suggest that thresher
sharks (both bigeye and common) have likely undergone a decline in
abundance in this region. However, the conflicting evidence between
logbook and observer data showing opposite trends in thresher shark
abundance cannot be fully resolved at this time. Data are not available
in the petition or in our own files to assess the trend in population
abundance in this region since 2006, or to assess the trend specific to
the bigeye thresher shark. Because the logbook data from this region
show consistent evidence of a significant and continued decline in
thresher sharks, we must consider this information in our 90-day
determination. Additionally, in the Southeastern United States, studies
show significant declines in the species, with decreases in CPUE
indicating that the population of A. superciliosus has declined by 70
percent from historical levels (Beerkircher et al., 2002).
For the Northeast Atlantic, there are no population abundance
estimates available, but data indicate that the species is taken in
driftnets and gillnets. In the Mediterranean Sea, estimates show
significant declines in thresher shark abundance during the past two
decades, reflecting data up to 2006. According to historical data
compiled using a generalized linear model, thresher sharks have
declined between 96 and 99 percent in abundance and biomass in the
Mediterranean Sea (Ferretti et al., 2008). Overall, the bigeye thresher
shark has been poorly documented in the Mediterranean and is considered
scarce or rare.
In the Eastern Central Pacific, logbook data show a historical
decline of thresher sharks due to pelagic fishing fleet operations.
Trends in abundance and biomass of thresher sharks in the eastern
tropical Pacific Ocean were estimated by comparison of pelagic longline
research surveys in the 1950s with recent data (1990s); these data were
collected by observers on pelagic longline fishing vessels and
standardized to account for differences in depth and soak time. This
analysis estimated a decline in combined thresher abundance of 83
percent and a decline in biomass to approximately 5 percent of virgin
levels (Ward and Myers, 2005).
In other areas of the world, estimates of thresher shark abundance
are limited. Bigeye threshers are recorded in the catches of fisheries
operating in the Indo-West Pacific, but catches of the species are
likely very under-reported. An analysis of purse seine and longline
observer data from the Western and Central Pacific produced no clear
catch trends for thresher sharks (Alopias spp.); however, shark data
from observer data sets are constrained by a lack of observer coverage,
particularly for the North Pacific, and for the purse seine fishery by
the physical practicalities of onboard sampling (Clarke, 2011).
Additionally, this study detected a significant decrease in median size
for thresher sharks in tropical areas, most likely reflective of trends
in bigeye threshers as they are the most commonly encountered species
in this region. While catch data are incomplete and cannot be used to
estimate abundance levels or determine the magnitude of catches or
trends for bigeye threshers at this time, pelagic fishing effort in
this region is high, with reported increases in recent years (IUCN
assessment, 2009).
In conclusion, across the species' global range we find evidence
suggesting that population abundance of the bigeye thresher shark is
declining or, in the Northwest Atlantic Ocean, may be stable at a
diminished abundance. While data are still limited with respect to
population size and trends, we find the petition and our files
sufficient in presenting substantial information on bigeye thresher
shark abundance, trends, or status to indicate the petitioned action
may be warranted.
ESA Section 4(a)(1) Factors
The petition indicated three main categories of threats to the
bigeye thresher shark: overutilization for commercial, recreational,
scientific, or educational purposes; the inadequacy of existing
regulatory mechanisms; and other natural or manmade factors affecting
its continued existence. We discuss each of these below based on
information in the petition, and the information readily available in
our files.
Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
The petition states that ``the bigeye thresher has shown
substantial population declines in every area where sufficient
historical and current population data exists'' and lists four
categories of overutilization: historical, directed, incidental, and
recreational. The petition describes historical exploitation as the
first category of overutilization for the species, predominantly in the
Northwest and Central Atlantic and Eastern Central Pacific. In the
Northwest and Central Atlantic, bigeye threshers were historically
caught in pelagic longline fisheries. Bigeye threshers have been a
prohibited species in all commercial fisheries in the U.S. Atlantic
since 2000. Since these regulations became effective in 2000, relative
abundance of thresher sharks (again, only at the genus level) in the
western North Atlantic Ocean appears to have stabilized or even be
increasing since the late 1990s (Baum and Blanchard, 2010;
Cort[eacute]s, 2007). However, it should be noted that bigeye threshers
are still caught as bycatch and occasionally landed in the Northwest
Atlantic Ocean despite its prohibited status (NMFS, 2012; 2013), which
may hinder the ability of the population to rebound from the historical
declines.
As previously mentioned, the petition also states that logbook data
from the Eastern Central Pacific shows a historical decline of bigeye
thresher sharks due to pelagic fishing fleet operations known to take
this species. Trends in abundance and biomass of thresher sharks in the
eastern tropical Pacific Ocean were estimated by comparison of pelagic
longline research surveys in the 1950s with recent data (1990s); these
data were collected by observers on pelagic longline fishing vessels
and standardized to account for differences in depth and soak time. For
example, in the 1990's, longliners deployed more hooks (averaging 2240
hooks per day compared to 322 hooks in the 1950s) over a wider depth
range
[[Page 48065]]
(down to 600 m compared to 200 m) for longer periods. Thus, while
catches of thresher sharks increased (from 112 threshers in the 1950s
survey to 511 threshers in the 1990s survey), this analysis estimated a
decline in combined thresher abundance of 83 percent, with a decline in
mean biomass to approximately 5 percent of virgin levels and a decline
in mean body mass from 17 kg to 12 kg). While this analysis was not
species-specific (Ward and Myers, 2005), we must consider this
information in our 90-day finding given the potential significant
population decline of bigeye threshers in this region.
In addition to broad commercial harvest of the species, the
petition states that direct catch related to the shark fin trade has
resulted in population decline, and that bigeye thresher sharks are
targeted and preferentially retained for their fins. For example, the
petition stated in the Indo-West Pacific, a single thresher fin can
fetch US $250, creating incentives that would drive overutilization.
However, this statement is not entirely correct. While it is true that
high prices are paid for thresher sharks, the value of US $250 was not
for a single fin, but rather for the entire shark (Gilman et al.,
2007). Still, in comparison to other sharks (e.g., shortfin mako only
fetches US $50 per shark), thresher sharks appear to be highly valued
and consequently targeted for both their meat and fins. While the
petition did not provide any information connecting population declines
as a result of this direct catch, evidence suggests that the three
thresher shark species, collectively, may account for approximately 2.3
percent of the fins auctioned in Hong Kong, the world's largest fin-
trading center (Clarke, 2006). This translates to 0.4 million to 3.9
million threshers that may enter the global fin trade each year
(Clarke, 2006), with bigeye thresher having the highest value and
vulnerability to fishing compared to the other thresher species
(Cort[eacute]s, 2010); still, the relative proportion of each thresher
shark species comprising the shark fin trade is not available in this
genus-level assessment and information on the species-specific impact
of this harvest on bigeye thresher shark abundance is not provided by
the petitioner. However, we found species-specific evidence in our
files that bigeye threshers may be highly utilized in the shark fin
trade. In a genetic barcoding study of shark fins from markets in
Taiwan, bigeye threshers were one of 20 species identified and
comprised 0.07 percent of collected fin samples. Additionally, thresher
sharks comprised 15 percent of fins genetically tested from markets
throughout Indonesia (the largest shark catching country in the world),
with bigeye threshers making up an estimated 7.6 percent of all fins
tested. The high frequency of bigeye threshers in the markets across
Indonesia provides some evidence that they are not just caught
incidentally, but are targeted by large-scale fisheries (Sembiring,
2015). In another genetic barcoding study of fins from United Arab
Emirates, the fourth largest exporter in the world of raw dried shark
fins to Hong Kong, the authors found that the Alopiidae family
represented 5.9 percent of the trade from Dubai, with bigeye thresher
comprising 2.31 percent (Jabado et al., 2015). Overall, evidence that
bigeye thresher sharks (and threshers in general) are highly valued for
their fins, are possibly targeted in some areas, and comprise a portion
of the Hong Kong fin-trading auction suggests that this threat may
impact the species.
In the Indian Ocean, the status and abundance of shark species is
poorly known despite a long history of research and more than 60 years
of commercial exploitation by large-scale tuna fisheries (Romanov et
al., 2010). Pelagic sharks, including bigeye threshers, are targeted in
various fisheries, including semi-industrial, artisanal, and
recreational fisheries. Countries that fish for various pelagic species
of sharks include: Egypt, India, Iran, Oman, Saudi Arabia, Sudan,
United Arab Emirates, and Yemen, where the probable or actual status of
shark populations is unknown, and Maldives, Kenya, Mauritius,
Seychelles, South Africa, and United Republic of Tanzania, where the
actual status of shark populations is presumed to range from fully
exploited to over-exploited (Young, 2006). In 2013, an Ecological Risk
Assessment (ERA) was developed by the Indian Ocean Tuna Commission
(IOTC) Scientific Committee to quantify which shark species are most at
risk from the high levels of pelagic longline fishing pressure. In this
ERA, the IOTC Scientific Committee noted that A. superciliosus received
a high vulnerability ranking (No. 2) for longline gear, as the species
is characterized as one of the least productive shark species, and is
highly susceptible to catch in longline fisheries. The ERA also noted
that the available evidence indicates considerable risk to the status
of the Indian Ocean Alopias spp. stocks at current catch levels, which,
from 2000-2011 was estimated to be 22,811 mt (Merua et al., 2013).
Indirect catch is another category of overutilization identified by
the petition, which states that post-release mortality may be high in
the species. However, no information is provided in the petition to
connect the effect of bycatch on population declines of the species. In
the Northeast Atlantic and Mediterranean, while there are no target
fisheries for thresher sharks, they are taken as bycatch in various
fisheries, including the Moroccan driftnet fishery in the southwest
Mediterranean. They are also caught by industrial and semi-industrial
longline fisheries and by artisanal gillnet fisheries. In our files, we
found evidence that in the last two decades, thresher sharks (common
and bigeye) have declined between 96 and 99 percent in abundance and
biomass in the Mediterranean Sea (Ferretti, 2008).
Although bigeye thresher sharks have been a prohibited species in
U.S. Atlantic commercial fisheries since 2000, they are still
incidentally taken as bycatch on pelagic longlines and in gillnets on
the East Coast. For example, in our files, we found that since the
prohibition on bigeye threshers came into effect in 2000, approximately
1,493 lbs, dressed weight (677 kg) of bigeye thresher were landed in
the Atlantic (NMFS, 2012; 2014) despite its prohibited status. In 2010,
the United States reported that bigeye thresher represented the second
largest amount of dead discards in the Atlantic commercial fleet,
reporting a total of 46 t (NOAA, 2010 Report to ICCAT). In 2011, this
number dropped to 27 t of bigeye thresher dead discards (NOAA, 2011
Report to ICCAT). Further, several recent reports assessing the
vulnerability of bigeye threshers and other pelagic sharks to bycatch
in the U.S. Atlantic pelagic longline fishery characterized the bigeye
thresher as highly vulnerable (Cortes, 2010; Cortes, 2012; Gallagher et
al., 2014). These landings and dead discards may be linked to declines
in the species across the Northwest Atlantic portion of its range;
however, as discussed earlier, conflicting logbook and observer data
decrease the certainty of these trends (Cort[eacute]s, 2007; Baum and
Blanchard, 2010).
In the Southwest Atlantic Ocean, off the coast of Brazil, bigeye
threshers represent almost 100 percent of thresher sharks caught in
longline fisheries (Amorin, 1998). The landed catch and CPUE of bigeye
thresher shark in this fishery increased from 1971 to 1989, and then
gradually decreased from 1990 to 2001; however, this does not
necessarily reflect stock abundance because changes in the depth of
fishing operations also occurred, which may
[[Page 48066]]
have affected the time series. Thus, further information is needed to
resolve this. In our files, we found that bigeye threshers are also
taken in Uruguayan longline fisheries at similar levels. In one study,
observer data from 2001-2005 recorded a total of 295 A. superciliosus
specimens, in which the species' abundance was characterized as ``low''
despite high fishing effort (Berrondo et al., 2007). Further, observer
data from 1992-2000 showed that bigeye threshers experience high
mortality in longline fisheries in the Southwest Atlantic, with 54
percent dead upon capture (Beerkircher et al., 2002). Given the
declines reported in other areas for which data are available
throughout other parts of the species' range and the high fishing
pressure from fleets throughout the Southwest Atlantic, A.
superciliosus may be experiencing a level of exploitation in this part
of its range that may increase its risk of extinction.
In the Eastern Central Pacific, the petition points to the fact
that bigeye threshers have been recorded as bycatch in purse seine
fleets operating in this region, in which bigeye threshers comprised 1
percent of shark species caught during a Shark Characteristics Sampling
Program conducted from 1994-2004 (Roman-Verdesoto and Orozco-
Z[ouml]ller, 2005). Bycatch for this report was defined as sharks that
were discarded dead after being removed from the net and placed on the
vessel. Since 2010, catches of thresher sharks in this fishery have
fluctuated between 10 t and 14 t; however, in a preliminary
productivity-susceptibility assessment, bigeye threshers were
characterized as having a low susceptibility to this fishery (IAATC,
2009). Complete bycatch and discard data are not readily available from
longline fleets in the Eastern Pacific. In our files, we found that
bigeye thresher sharks are minor components of U.S. West Coast
fisheries, taken incidentally and presumably not overexploited, at
least locally. The bigeye thresher occurs regularly but in low numbers,
comprising only approximately 9 percent of common thresher catch (PFMC,
2003). Overall, we found that apart from blue and silky sharks, there
are no stock assessments available for shark species in the Eastern
Pacific, and hence the impacts of bycatch on the population are unknown
(IATTC, 2014). However, despite a lack of information regarding present
levels of bycatch occurring in other fisheries throughout the Eastern
Pacific, as described earlier, thresher sharks were estimated to have
experienced an 83 percent decline in this part of the species' range as
a result of fishing mortality in longline fisheries. Given the high
rates of bycatch-related mortality observed in this species throughout
other parts of its range (e.g., Northwest and Southwest Atlantic,
Indian Ocean, and Central Pacific), it is likely the species
experiences similar rates of bycatch-related mortality in this part of
its range as well. Thus, it is likely that the historical and continued
levels of exploitation in this part of the species' range are impacting
the species, such that listing may be warranted.
We found evidence that bigeye threshers are known to interact with
longline fisheries throughout the Indo-Pacific. In the Western and
Central Pacific, where sharks represent 25 percent of the longline
fishery catch, observer data showed that bigeye thresher shark is the
7th most commonly bycaught species of shark out of a total 49 species
reported by observers (Molony, 2007). We found that bigeye threshers
are commonly taken as bycatch in longline fisheries in the Republic of
the Marshall Islands, in which they exhibit at-vessel and/or post-
release mortality of 50 percent, and nearly 99 percent are finned and
subsequently discarded (Bromhead, 2012). Further, in a species status
snapshot for thresher sharks in the Western and Central Pacific, Clarke
et al., (2011) identified significant decreasing size trends for
thresher sharks in tropical areas, which may be indicative of
population declines in these areas. It is thought that these findings
most likely reflect trends of bigeye threshers as they are the most
common thresher species encountered in this region, with catches of
common and pelagic threshers characterized as rare or uncommon. Bigeye
threshers are also commonly caught by Hawaii longline fisheries,
particularly on deep-set gear (Walsh et al., 2009), and represented 4.1
percent of shark catches from 1995-2006. While catches of thresher
sharks (Alopias spp.) have trended upward, actual landings of thresher
sharks in Hawaii have decreased from 50 mt in 2001 to 16 mt in 2010,
presumably due to the implementation of state and Federal laws
regarding shark finning (NMFS, 2011).
In the Indian Ocean, while fisheries are directed at other species,
bigeye threshers are commonly caught as bycatch and catch rates are
considered high (IOTC, 2011; Hererra and Pierre, 2011). For example,
bycatch of bigeye threshers has been recorded in Japanese and Taiwanese
longline fisheries. According to Japanese observer data, 162 bigeye
threshers were bycaught in 6 months (from July 2010 to January 2011).
These data do not include live-released bigeye thresher sharks (Ardill
et al., 2011), which reportedly have high post-release mortality rates
(IOTC, 2014). Observer data from Taiwanese longline fleets (with
coverage ranging from only 2.2 percent in 2004 to 20.8 percent in 2007)
recorded a total of 445 bigeye threshers bycaught from 2004-2008, with
approximately 61 percent discarded (Huang and Liu, 2010). Hooking
mortality is apparently very high in this region; therefore, the IOTC's
regulation 10/12 that prohibits the onboard retention of any part of
any thresher species and promotes live release of thresher sharks may
be ineffective for the conservation of bigeye thresher sharks. For
example, in the Portuguese longline fleet, bigeye threshers experienced
a high rate of at-vessel mortality of 68.4 percent (n = 19) from May to
September 2011 (Ardill et al., 2011). The IOTC reported in 2014 that
``maintaining or increasing effort in this region will probably result
in further declines in biomass, productivity and CPUE'' for bigeye
threshers (IOTC, 2014).
Overall, there is considerable uncertainty regarding the actual
levels of bycatch of bigeye thresher shark occurring throughout its
range; however, it is likely that these rates are significantly under-
reported due to a lack of comprehensive observer coverage in areas of
its range in which the highest fishing pressure occurs, as well as a
tendency for fishers to not record discards in fishery logbooks.
Nevertheless, given the prevalence of bigeye threshers as incidental
catch throughout its range and the species' observed high hooking and
post-release mortality rates, combined with the species' low
productivity, bycatch-related fishing mortality may be a threat placing
the species at an increased risk of extinction.
The petition identified recreational fishing as the fourth category
of overutilization. In our files, we found evidence that thresher
sharks, particularly common threshers, are valued by recreational sport
fishermen throughout the species' U.S. East Coast and West Coast range;
however, bigeye threshers do not appear to be as important in
recreational fisheries and are largely prohibited in many fisheries
within the United States. The petition described results from Heberer
(2010), which identified the potential negative impact of recreational
fishing on the survival of congener, A. vulpinus, by assessing post-
release survivorship of sharks captured using the caudal fin-based
techniques used by most
[[Page 48067]]
recreational fishermen in southern California. As previously described,
thresher sharks use their elongate upper caudal lobe to immobilize prey
before it is consumed, and the majority of common thresher sharks
captured in the southern California recreational fishery are hooked in
the caudal fin and hauled-in backwards. This is significant because
common threshers are obligate ram ventilators that require forward
motion to ventilate the gills (Heberer, 2010), and the reduced ability
to extract oxygen from the water during capture, as well as the stress
induced from these capture methods, may influence recovery following
release. The findings of Heberer (2010) demonstrate that large tail-
hooked common thresher sharks with prolonged fight times (>=85 min)
exhibit a heightened stress response, which may contribute to an
increased mortality rate. This work suggests, especially for larger
thresher sharks, that recreational catch-and-release may not be an
effective conservation-based strategy for the species. A recent paper
by Sepulveda (2014) found similar evidence for high post-release
mortality of recreationally caught common thresher sharks in the
California recreational shark fishery. Their results demonstrated that
caudal fin-based angling techniques, which often result in trailing
gear left embedded in the shark, can negatively affect post-release
survivorship. This work suggests that mouth-based angling techniques
can, when performed properly, result in a higher survivorship of
released sharks. The petition argues that because common thresher
sharks may exhibit high mortality in recreational fisheries that bigeye
threshers would likely exhibit similar results. While this may be true,
in our files, we found no evidence to suggest that bigeye threshers are
declining (or responding in a negative fashion) as a result of
utilization by recreational fisheries. While it is not known if this
species enters the California recreational fishery on any regular
basis, presumably only few are taken. Further, there are no records
from the recreational fishery off Oregon or Washington (NMFS, 2007),
and in fact, fishing of all thresher species is prohibited in
Washington. Likewise, in the Northwest Atlantic, bigeye threshers have
been prohibited in recreational fisheries by Federal regulations since
1999. Further, U.S. states from Maine to Florida have adopted the
Interstate Fisheries Management Plan (FMP) for Atlantic Coastal Sharks
adopted by the Atlantic States Marine Fisheries Commission (ASMFC),
which prohibits recreational fishing of bigeye threshers. Finally,
since prohibition of this species was implemented in 1999, there has
been no observed recreational harvest of this species, with the
exception of years 2002 and 2006 (NMFS, 2014). The petition did not
provide, nor could we find in our files, any information regarding the
threat of recreational fishing to bigeye threshers throughout the rest
of the species' range. Thus, we find that the information presented in
the petition, and in our files, does not comprise substantial
information that would lead us to conclude the species may have an
increased risk of extinction from overutilization as a result of
recreational fishing activities.
Overall, trends in the North West and Central Atlantic Ocean
suggest that the species experienced historical declines from
overexploitation, but may be stabilized and possibly increasing in
recent years, although there is considerable uncertainty regarding
these trends. Elsewhere across the species' range, information in the
petition and in our files suggests that the species may continue to
experience declines as a result of overutilization from both direct and
indirect fishing pressure. In summary, the petition, references cited,
and information in our files comprise substantial information
indicating that listing may be warranted because of overutilization for
commercial purposes.
Inadequacy of Existing Regulatory Mechanisms
The petition points to ``virtually non-existent international
regulatory protections'' to assert that bigeye threshers qualify for
listing due to the inadequacy of existing regulatory mechanisms. For
example, the petition mentions the lack of protections from the
Convention on International Trade of Endangered Species (CITES) for the
bigeye thresher shark, but then states that even if the species was
listed under CITES, it would still be inadequate due to the fact that a
CITES listing would only address threats associated with the
international trade of the species, and would not address such impacts
as bycatch. Although a CITES Appendix II listing or international
reporting requirements would provide better data on the global catch
and trade of the bigeye thresher shark, the lack of a CITES listing or
requirements does not suggest that current regulatory mechanisms are
inadequate to protect the bigeye thresher shark population from
becoming threatened or endangered under the ESA. The petition also
asserts that the recent listing of bigeye thresher shark under Appendix
II of the Convention of Migratory Species (CMS) is also inadequate
given that the United States and other range states are not Member
Parties to CMS and are therefore not bound by the requirements imposed
by the Appendix II listing. The petition further states that the
Convention text is only suggestive and not self-executing upon the
listing of a species. On the contrary, we find that a CMS Appendix II
listing now encourages international cooperation towards conservation
of the species, and although the United States is not currently a party
to CMS, the United States is a signatory to a number of CMS instruments
for the conservation of various marine species, including sharks.
The petition also asserts that finning regulations and species-
specific retention bans are ``inadequate'' for protecting the bigeye
thresher shark species because they may still be caught, either
directly or indirectly. The petition also cites several regional
fisheries management organizations (RFMOs) that implement a 5 percent
fin-to-carcass ratio regulation, describes what the petitioner contends
are potential loopholes in those regulations, and states that these
general regulations are inadequate for the bigeye thresher shark, whose
larger fins make it a more targeted species. The petition further
contends that species-specific retention bans for bigeye threshers,
such as the ones implemented by ICCAT and IOTC that specifically
prohibit the retention, transshipping, landing, storing, selling, or
offering for sale any part or whole carcass of bigeye thresher sharks,
are also inadequate largely because they do not address incidental
catch and subsequent high mortality rates of the species. Based on the
information presented in the petition and in our files, we find that
the bigeye thresher shark is highly valued for its fins, and can be
identified in the shark fin market at the species level. While
regulations banning the finning of sharks are a common form of shark
management and have been adopted by far more countries and regional
fishery management organizations than the petition lists (see HSI,
2012), we agree with the petition that due to high rates of hooking
mortality observed in this species as a result of incidental catch,
prohibitions on the retention of bigeye thresher or restrictions on the
finning of sharks may not be adequate to protect the bigeye thresher
from fishing mortality rates that may contribute to its extinction
risk, especially given the species' significantly low productivity and
intrinsic rate of population increase.
[[Page 48068]]
In addition to the inadequacy of international regulations, the
petition states that ``while the U.S. has attempted to protect the
bigeye thresher shark in U.S. waters, piecemeal protections that fail
to cover the species throughout its migratory range have proven to be
unsuccessful.'' Though U.S. regulations by their jurisdictional nature
only cover U.S. fishers, we do not agree that this makes them
inadequate. We find that U.S. national fishing regulations include
numerous regulatory mechanisms for both sharks in general, and bigeye
threshers specifically, that may help protect the species. For example,
in the U.S. Atlantic, the bigeye thresher has been a prohibited species
in both commercial and recreational fisheries since 2000 and 1999,
respectively, under the 1999 Fishery Management Plan for Atlantic
Tunas, Swordfish, and Sharks. In addition, current management measures
for the Atlantic shark fisheries include the following: commercial
quotas, commercial retention limits, limited entry, time-area closures,
and recreational bag limits. Sharks are required to be landed with fins
naturally attached to the carcass. Additionally, several U.S. states
have prohibited the sale or trade of shark fins/products as well,
including Hawaii, Oregon, Washington, California, Illinois, Maryland,
Delaware, New York, and Massachusetts, subsequently decreasing the
United States' contribution to the fin trade. For example, after the
state of Hawaii prohibited finning in its waters in 2000 and required
shark fins to be landed with their corresponding carcasses in the
state, shark fin imports from the United States into Hong Kong declined
significantly (54 percent decrease, from 374 to 171 tonnes), as Hawaii
could no longer be used as a fin trading center for the international
fisheries operating and finning in the Central Pacific (Miller, 2014).
Except for smooth dogfish (Mustelus canis), the U.S. Shark Conservation
Act of 2010 protects all shark species, making it illegal to remove any
of the fins of a shark (including the tail) at sea; to have custody,
control, or possession of any such fin aboard a fishing vessel unless
it is naturally attached to the corresponding carcass; to transfer any
such fin from one vessel to another vessel at sea, or to receive any
such fin in such transfer, without the fin naturally attached to the
corresponding carcass; or to land any such fin that is not naturally
attached to the corresponding carcass, or to land any shark carcass
without such fins naturally attached. However, we do agree with the
petition that these regulations do not address the issue of bycatch-
related mortality of the species, especially considering the fact that
bigeye threshers are still bycaught in U.S. fisheries.
Overall, while measures may be implemented to reduce bycatch, we
found no evidence that these measures have been incorporated into
common practice throughout the species' range, particularly in areas
where fishing pressure is most concentrated. Further, while numerous
finning and species-specific retention bans have been implemented,
these regulations fail to address the species' high rate of bycatch-
related mortality. In summary, the petition, references cited, and
information in our files comprise substantial information indicating
that the species may be impacted by the inadequacy of regulatory
mechanisms in parts of its range, such that listing may be warranted.
Other Natural or Manmade Factors Affecting Its Existence
The petition states that the biological constraints of the bigeye
thresher shark, such as its low reproduction rate (typically 2-4 pups a
year), coupled with a late age of maturity (approximately 12-14 years
for females, and slightly earlier for males, between 9-10 years)
contribute to the species' vulnerability to harvesting and its
inability to recover rapidly. We agree with the petition that the
bigeye thresher shark exhibits relatively slow growth rates and low
fecundity. An ecological risk assessment conducted to inform the
International Commission for the Conservation of Atlantic Tunas (ICCAT)
categorized the relative risk of overexploitation of the 11 major
species of pelagic sharks, including the bigeye thresher shark
(Cort[eacute]s et al., 2010, 2012). The study derived an overall
vulnerability ranking for each of the 11 species, which was defined as
``a measure of the extent to which the impact of a fishery [Atlantic
longline] on a species will exceed its biological ability to renew
itself'' (Cort[eacute]s et al., 2010, 2012). This robust assessment
found that bigeye thresher sharks have a combination of low
productivity and high susceptibility to pelagic longline gear, which
places the bigeye thresher at high risk of overexploitation to the
combined pelagic longline fisheries in the Atlantic Ocean
(Cort[eacute]s et al., 2010, 2012). In fact, of the 11 species examined
in this study, Atlantic bigeye thresher sharks were identified as one
of the most vulnerable and least productive shark species. Even within
the genus Alopias, the bigeye thresher shark has the slowest population
growth rate of all thresher sharks, with an exceptionally low potential
annual rate of population increase (0.002-0.009 or 1.6 percent) under
sustainable exploitation (Cort[eacute]s, 2008; Dulvy et al., 2008;
Smith et al., 2008). This makes them particularly vulnerable to any
level of fisheries exploitation, whether targeted or caught as bycatch
in fisheries for other species. Given that bigeye thresher sharks are
caught regularly as incidental bycatch throughout its range and
experience high mortality rates as a result, and that the species may
be targeted in some areas for its fins, the species' growth and
reproductive factors may inhibit the species' ability to recover from
even moderate levels of exploitation, thus placing the bigeye thresher
shark at an increased risk of extinction as a result. In summary, the
petition, references cited, and information in our files comprise
substantial information indicating that the species is impacted by
``other natural or manmade factors,'' including the life history trait
of slow productivity, such that listing the species may be warranted.
Summary of Section 4(a)(1) Factors
We conclude that the petition does not present substantial
scientific or commercial information indicating that the ESA section
(4)(a)(1) threats of ``present or threatened destruction, modification,
or curtailment of its habitat or range'' or ``disease or predation''
may be causing or contributing to an increased risk of extinction for
the global population of the bigeye thresher shark. However, we do
conclude that the petition and information in our files present
substantial scientific or commercial information indicating that the
section 4(a)(1) factor ``overutilization for commercial, recreational,
scientific, or educational purposes,'' as well as ``inadequacy of
existing regulatory mechanisms'' and ``other manmade or natural
factors,'' may be causing or contributing to an increased risk of
extinction for the species.
Petition Finding
Based on the above information and the criteria specified in 50 CFR
424.14(b)(2), we find that the petition and information readily
available in our files present substantial scientific and commercial
information indicating that the petitioned action of listing the bigeye
thresher shark worldwide as threatened or endangered may be warranted.
Therefore, in accordance with section 4(b)(3)(A) of the ESA and NMFS'
implementing regulations (50
[[Page 48069]]
CFR 424.14(b)(3)), we will commence a status review of the species.
During the status review, we will determine whether the species is in
danger of extinction (endangered) or likely to become so within the
foreseeable future (threatened) throughout all or a significant portion
of its range. We now initiate this review, and thus, we consider the
bigeye thresher shark to be a candidate species (69 FR 19975; April 15,
2004). Within 12 months of the receipt of the petition (April 27,
2016), we will make a finding as to whether listing the species as
endangered or threatened is warranted as required by section 4(b)(3)(B)
of the ESA. If listing the species is found to be warranted, we will
publish a proposed rule and solicit public comments before developing
and publishing a final rule.
Information Solicited
To ensure that the status review is based on the best available
scientific and commercial data, we are soliciting information relevant
to whether the bigeye thresher shark is endangered or threatened.
Specifically, we are soliciting information in the following areas: (1)
Historical and current distribution and abundance of this species
throughout its range; (2) historical and current population trends; (3)
life history in marine environments, including identified nursery
grounds; (4) historical and current data on bigeye thresher shark
bycatch and retention in industrial, commercial, artisanal, and
recreational fisheries worldwide; (5) historical and current data on
bigeye thresher shark discards in global fisheries; (6) data on the
trade of bigeye thresher shark products, including fins, jaws, meat,
and teeth; (7) any current or planned activities that may adversely
impact the species; (8) ongoing or planned efforts to protect and
restore the species and its habitats; (9) population structure
information, such as genetics data; and (10) management, regulatory,
and enforcement information. We request that all information be
accompanied by: (1) Supporting documentation such as maps,
bibliographic references, or reprints of pertinent publications; and
(2) the submitter's name, address, and any association, institution, or
business that the person represents.
References Cited
A complete list of references is available upon request to the
Office of Protected Resources (see ADDRESSES).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 5, 2015.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2015-19551 Filed 8-10-15; 8:45 am]
BILLING CODE 3510-22-P