Endangered and Threatened Wildlife and Plants; Notice of 12-Month Finding on Petitions To List Porbeagle Shark as Threatened or Endangered Under the Endangered Species Act (ESA), 50463-50482 [2016-18101]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 81, Number 147 (Monday, August 1, 2016)]
[Notices]
[Pages 50463-50482]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-18101]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[Docket No. 150122069-6596-02]
RIN 0648-XD740


Endangered and Threatened Wildlife and Plants; Notice of 12-Month 
Finding on Petitions To List Porbeagle Shark as Threatened or 
Endangered Under the Endangered Species Act (ESA)

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; 12-month finding and availability of status review 
document.

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SUMMARY: We, the National Marine Fisheries Service, have completed a 
comprehensive status review under the Endangered Species Act (ESA) for 
porbeagle shark (Lamna nasus) in response to petitions to list this 
species. Based on the best scientific and commercial information 
available, including the status review report (Curtis et al., 2016), 
and taking into account ongoing efforts to protect these species, we 
have determined that porbeagle sharks do not warrant listing at this 
time. This review identified two Distinct Population Segments (DPS)--
North Atlantic and Southern Hemisphere--of porbeagle sharks. We 
conclude that neither is currently in danger of extinction throughout 
all or a significant portion of its range or likely to become so in the 
foreseeable future. We also conclude that the species itself is not 
currently in danger of extinction throughout all or a significant 
portion of

[[Page 50464]]

its range or likely to become so in the foreseeable future.

DATES: This finding was made on August 1, 2016.

ADDRESSES: The status review document for porbeagle sharks is available 
electronically at: https://www.nmfs.noaa.gov/pr/species/notwarranted.htm. You may also receive a copy by submitting a request 
to the Protected Resources Division, NMFS GARFO, 55 Great Republic 
Drive, Gloucester, MA 01930, Attention: Porbeagle Shark 12-month 
Finding.

FOR FURTHER INFORMATION CONTACT: Julie Crocker, NMFS Greater Atlantic 
Regional Fisheries Office, 978-282-8480 or Marta Nammack, NMFS Office 
of Protected Resources, 301-427-8469.

SUPPLEMENTARY INFORMATION: 

Background

    We, the National Marine Fisheries Service (NMFS), received a 
petition, dated January 20, 2010, from Wild Earth Guardians (WEG) 
requesting that we list porbeagle sharks throughout their entire range, 
or as Northwest Atlantic, Northeast Atlantic, and Mediterranean DPSs 
under the ESA. WEG also requested that we designate critical habitat 
for the species. We also received a petition, dated January 21, 2010, 
from the Humane Society of the United States (HSUS) requesting we list 
a Northwest Atlantic DPS of porbeagle shark as endangered. In response 
to these petitions, we published a ``negative'' 90-finding on July 12, 
2010, in which we concluded that the petitions did not present 
substantial scientific and commercial information indicating that 
listing under the ESA may be warranted.
    In August 2011, the petitioners filed complaints in the U.S. 
District Court for the District of Columbia challenging our denial of 
the petitions. On November 14, 2014, the court published a Memorandum 
Opinion granting the plaintiffs' requests for summary judgment in part, 
denying our request for summary judgment, and vacating the 2010 90-day 
finding for porbeagle sharks. The court ordered us to prepare a new 90-
day finding. The court entered final judgment on December 12, 2014 
(remand). The new 90-day finding, which published on March 27, 2015 (80 
FR 16356), was based primarily on information that had become available 
since 2010, including a new Canadian assessment of the Northwest 
Atlantic stock and new information in recent proceedings from the 
International Convention for the Conservation of Atlantic Tunas 
(ICCAT), regulatory documents, published literature, and Federal 
Register notices as well as the information contained in the original 
petitions. We accepted the 2010 petitions and initiated a review of the 
status of the species consistent with the ESA mandate that listing 
determinations should be made on the basis of the best scientific and 
commercial information available. Under the ESA, if a petition is found 
to present substantial scientific or commercial information that the 
petitioned action may be warranted, a status review shall be promptly 
commenced (16 U.S.C. 1533(b)(3)(A)).
    As described in the 90-day finding (80 FR 16356, March 27, 2015), 
new assessments, management actions, and other information became 
available subsequent to the 2010 90-day finding. This information 
indicated that the petitioned actions may be warranted and a review of 
the status of the species was initiated. The standard for making a 
positive 90-day finding (e.g., that a petitioned action ``may be 
warranted'') is low, and if there is information that can be 
interpreted in more than one way, then a status review may be conducted 
in order to delve into the available information more thoroughly. We 
performed that more detailed review and determined that the best 
available scientific and commercial information taken together does not 
support a listing. This included an in-depth review of the available 
literature, including the new assessments described in the 90-day 
finding and additional reports on porbeagle sharks in the Southern 
Hemisphere. This review informed an Extinction Risk Assessment (ERA), 
which was conducted by a team with expertise in shark biology and 
ecology, stock assessment, population dynamics, and highly migratory 
species management. The status review and the ERA were independently 
peer reviewed by external experts, and other published and unpublished 
information was used to make this 12-month determination.

Listing Species Under the Endangered Species Act

    We are responsible for determining whether the porbeagle shark is 
threatened or endangered under the ESA (16 U.S.C. 1531 et seq.). To 
make this determination, we first consider whether a group of organisms 
constitutes a ``species'' under Section 3 of the ESA, then whether the 
status of the species qualifies it for listing as either threatened or 
endangered. Section 3 of the ESA defines species to include ``any 
subspecies of fish or wildlife or plants, and any distinct population 
segment of any species of vertebrate fish or wildlife which interbreeds 
when mature.'' A DPS is a vertebrate population or group of populations 
that is discrete from other populations in the species and significant 
in relation to the entire species. On February 7, 1996, NMFS and the 
U.S. Fish and Wildlife Service (USFWS; together, the Services) adopted 
a policy describing what constitutes a DPS of a taxonomic species (61 
FR 4722). Under the joint DPS policy, we consider the following when 
identifying a DPS: (1) The discreteness of the population segment in 
relation to the remainder of the species or subspecies to which it 
belongs; and (2) the significance of the population segment to the 
species or subspecies to which it belongs.
    Section 3 of the ESA further defines an endangered species as ``any 
species which is in danger of extinction throughout all or a 
significant portion of its range'' and a threatened species as one 
``which is likely to become an endangered species within the 
foreseeable future throughout all or a significant portion of its 
range.'' Thus, we interpret an ``endangered species'' to be one that is 
presently in danger of extinction. A ``threatened species,'' on the 
other hand, is not presently in danger of extinction, but is likely to 
become so in the foreseeable future (that is, at a later time). In 
other words, the primary statutory difference between a threatened and 
endangered species is the timing of when a species may be in danger of 
extinction, either presently (endangered) or in the foreseeable future 
(threatened). Section 4 of the ESA also requires us to determine 
whether any species is endangered or threatened as a result of any of 
the following five factors: The present or threatened destruction, 
modification, or curtailment of its habitat or range; overutilization 
for commercial, recreational, scientific, or educational purposes; 
disease or predation; the inadequacy of existing regulatory mechanisms; 
or other natural or manmade factors affecting its continued existence 
16 U.S.C. 1533(a)(1)(A)-(E)). Section 4(b)(1)(A) of the ESA requires us 
to make listing determinations based solely on the best scientific and 
commercial data available after conducting a review of the status of 
the species and after taking into account efforts being made by any 
state or foreign nation or political subdivision thereof to protect the 
species. In evaluating the efficacy of existing domestic protective 
efforts, we rely on the Services' joint Policy on Evaluation of 
Conservation Efforts When Making Listing Decisions (``PECE''; 68 FR 
15100; March 28, 2003) for any conservation efforts that have not been 
implemented

[[Page 50465]]

or have been implemented but not yet demonstrated effectiveness.

Status Review

    The status review report for porbeagle sharks is composed of two 
components: (1) A scientific literature review and analysis of the five 
ESA Section 4(a)(1) factors and (2) an assessment of the extinction 
risk. A biologist in NMFS' Greater Atlantic Region's Sustainable 
Fisheries Division with expertise in shark ecology was appointed to 
complete the first component, undertaking a scientific review of the 
life history and ecology, distribution and abundance, and an analysis 
of the ESA Section 4(a)(1) factors. An Extinction Risk Analysis (ERA) 
team was convened to conduct the extinction risk analysis using the 
information in the scientific review as a basis. The ERA team was 
comprised of a fishery management specialist from NMFS' Highly 
Migratory Species Management Division, two research fishery biologists 
from NMFS' Northeast and Southeast Fisheries Science Centers, and the 
Sustainable Fisheries Division biologist who did the scientific 
literature review and analysis of Section 4(a)(1) factors. The ERA team 
had group expertise in shark biology and ecology, population dynamics, 
highly migratory species management, and stock assessment science. The 
ERA team also reviewed the information in the scientific literature 
review. The status review report for porbeagle sharks (Curtis et al., 
2016) compiles the best available information on the status of the 
species as required by the ESA, provides an evaluation of the 
discreteness and significance of populations in terms of the DPS 
policy, and assesses the current and future extinction risk, focusing 
primarily on threats related to the five statutory factors set forth 
above. This report presents the ERA team's professional judgment of the 
extinction risk facing porbeagle sharks but makes no recommendation as 
to the listing status of the species. The status review report is 
available electronically at the Web site listed above.
    The status review report was subjected to independent peer review 
as required by the Office of Management and Budget Final Information 
Quality Bulletin for Peer Review (M-05-03; December 16, 2004). The 
status review report was peer reviewed by four independent specialists 
selected from government, academic, and scientific communities, with 
expertise in shark biology, conservation and management, and specific 
knowledge of porbeagle sharks. The peer reviewers were asked to 
evaluate the adequacy, quality, and completeness of the data considered 
and whether uncertainties in these data were identified and 
characterized in the status review as well as to evaluate the findings 
made in the ``Assessment of Extinction Risk'' section of the report. 
They were also asked to specifically identify any information missing 
or lacking justification, or whether information was applied 
incorrectly in reaching conclusions. All peer reviewer comments were 
addressed prior to finalizing the status review report. Comments 
received are posted online.
    We subsequently reviewed the status review report, cited 
references, and peer review comments, and concluded that the status 
review report, upon which this listing determination is based, provides 
the best available scientific and commercial information on porbeagle 
sharks. Much of the information discussed below on porbeagle shark 
biology, genetic diversity, distribution, abundance, threats, and 
extinction risk is attributable to the status review report. However, 
we have independently applied the statutory provisions of the ESA, 
including evaluation of the factors set forth in Section 4(a)(1)(A)-
(E); our regulations regarding listing determinations; and, our DPS and 
Significant Portion of its Range (SPR) policies in making the listing 
determination.

Taxonomy

    Porbeagle sharks belong to the family Lamnidae, genus Lamna, and 
species nasus. The petitioned subject is a valid species as defined 
under the ESA.

Distribution and Habitat Use

    Porbeagle sharks are found in both the Northern and Southern 
Hemispheres. They are commonly found in waters over the continental 
shelf, shelf edges, and in open ocean waters. In the Northern 
Hemisphere, they are found in the North Atlantic Ocean in pelagic and 
coastal waters in and adjacent to the Northeast coast of the United 
States, Newfoundland Banks, Iceland, Barents, Baltic, and North Seas, 
the coast of Western Europe down to the Northwest African coast, and 
the Mediterranean Sea. They are absent from waters of the North 
Pacific. In the Southern Hemisphere, they are distributed in a 
continuous band around the globe in temperate waters of the Southern 
Atlantic, Southern Indian, and Southern Pacific Oceans. Like other 
lamnid sharks, the porbeagle shark is endothermic (warm-blooded). There 
is no evidence suggesting that the range of the species has contracted.
    It prefers cold, temperate waters and does not occur in equatorial 
waters. Generally, porbeagle sharks prefer waters less than 18 [deg]C 
(64 [deg]F) but have been documented in waters ranging from 1-26 [deg]C 
(34-79 [deg]F) (Compagno, 2002; Francis et al., 2008; Skomal et al., 
2009). Porbeagle sharks are highly mobile and capable of making long-
distance migrations, though individuals often remain within a smaller 
range.
    The porbeagle shark is found from surface and inshore waters (less 
than 1 m (3 ft)) to deep (>1,000 m (>3,281 ft)) depths, with variations 
in depth distribution depending on the season and region (Compagno 
2001; Pade et al., 2009; Saunders et al., 2009; Skomal et al., 2009; 
Campana et al., 2010a; Francis et al., 2015). In the Northwest 
Atlantic, tagged sharks moved from the surface to 1300 m (4265 ft) with 
no difference in depths used during the day or night. Seasonal 
differences in depth distribution were observed (Campana et al., 
2010a). Mature female sharks tagged in the Northwest Atlantic moved to 
the Sargasso Sea, suggesting a pupping area (Campana et al., 2010a). 
Two relatively small tagging studies were conducted in the Northeast 
Atlantic. In these studies, porbeagle sharks ranged from the surface to 
500-700 m (1640-2297 ft) depth, and differences in vertical 
distribution during day and night were observed (Pade et al., 2009; 
Saunders et al., 2009). In a study in the Southern Hemisphere, Francis 
et al. (2015) evaluated the vertical movements of 10 porbeagle sharks. 
All of the sharks in the study dived to depths of at least 600 m (1969 
ft), with a maximum recorded depth of 1024 m (3360 ft) and vertical 
movements were observed.
    The porbeagle shark is a habitat generalist and not substantially 
dependent on any particular habitat type. Its use of habitat is 
influenced by temperature and prey distribution, but the shark has 
broad temperature tolerances and an opportunistic diet (Curtis et al., 
2016). The porbeagle shark is an opportunistic feeder, taking advantage 
of available prey (Joyce et al., 2002; Campana and Joyce 2004). The 
diet is characterized by a diverse range of pelagic, epipelagic, and 
benthic species, depending on what is available (Joyce et al., 2002). 
Prey species include teleosts (a large and diverse group of bony fish), 
including lancetfish, flounders, lumpfish, and Atlantic cod, and 
cephalopods, including squid (Joyce et al., 2002). In the Gulf of 
Maine, porbeagle sharks predominately feed on mackerel, herring, and 
other small fishes, other species of sharks, and squids (Collette and 
Klein-MacPhee, 2002).

[[Page 50466]]

Life History

    The porbeagle shark is an aplacental, viviparous species with 
oophagy. This means embryos develop inside eggs that are retained in 
the mother's body until the young are born live. There is no placental 
connection, and the eggs are consumed in utero during gestation and 
development (Jensen et al., 2002). Size at birth is approximately 58-67 
cm (22.8-26.4 inches) (Francis et al., 2008; Forselledo, 2012). 
Porbeagle sharks have low productivity, an 8-9 month gestation period 
(Jensen et al., 2002; Francis et al., 2008), and an average litter size 
of four pups (Jensen et al., 2002; Francis et al., 2008). Ages of 
sexual maturity are approximately 8 years for males and 13 years for 
females in the Northwest Atlantic (Jensen et al., 2002; Natanson et 
al., 2002; CITES, 2013) and 8-11 years for males and 15-18 years for 
females in New Zealand (Francis et al., 2008; CITES, 2013). The maximum 
age of porbeagle sharks is estimated at 46 years in an unfished 
population, but may exceed 65 years in the Southern Hemisphere 
(Natanson et al., 2002; ICCAT, 2009; CITES, 2013).
    In a comparison of life history characteristics of 38 shark 
species, the population growth rate of porbeagle sharks in the 
Northwest Atlantic was in the lower-third of the species examined. The 
reported population growth rate was 1.022 (values less than 1 indicate 
negative population growth rates) with a mean generation time of 
approximately 18 years (Cortes, 2002). Juvenile survival rates were 
among the highest of the shark species analyzed, resulting in high 
overall natural survival rates (84-90 percent). A recent assessment 
(Cortes et al., 2015) conducted by ICCAT found that the population 
growth rate for porbeagle sharks in the Atlantic ranked 13th highest 
out of 20 stocks and the generation time was on the order of 20 years. 
The generation time in the Southern Hemisphere is longer due to slower 
growth rates and greater estimated longevity. In sum, porbeagle sharks 
are a slow maturing, relatively long lived species with a relatively 
low population growth rate.

Population Structure

    Stocks are often used to define populations for fisheries 
management purposes. These stock management units are not equivalent to 
DPSs unless they also meet the criteria for identifying a DPS. As 
described in the report for the 2009 porbeagle stock assessment meeting 
(International Council for the Exploration of the Sea (ICES)/ICCAT, 
2009), four stocks have been identified in the Atlantic Ocean. These 
include two in the Northern Hemisphere--the Northwest and Northeast 
Atlantic stocks--and two in the Southern Hemisphere--the Southwest and 
Southeast Atlantic stocks. There may also be an Indo-Pacific stock in 
the Southern Hemisphere, but the stock boundaries remain unclear. The 
Northwest Atlantic stock includes porbeagle sharks from the waters on 
and adjacent to the continental shelf of North America, and the 
Northeast stock includes porbeagle sharks from the waters in and 
adjacent to the Barents Sea south to Northwest Africa, including the 
Mediterranean Sea. In defining stocks, a range of information is 
considered, including fisheries, biological, distribution, genetic, and 
tagging information. While these stocks do not necessarily equate to 
DPSs, they are useful delineations for discussing the population 
abundance and trends as this is how data for this species are 
frequently collected and reported.
    Tagging and genetic data help define stock structure. Tagging 
studies may use conventional or electronic tags to collect data on an 
animal's movements. Conventional tags have a unique number and contact 
information printed on them. When an animal with a tag is captured, 
scientists can use the tag number to identify the location and date of 
release as well as any other information recorded when the animal was 
tagged. This information, along with information recorded when the 
animal is recaptured, can be used to identify information such as how 
long the shark was at large, distance between release and recapture 
locations, and how much the animal grew during that time. There are 
several limitations to interpreting conventional tagging data. First, 
it relies on recapturing the animal and reporting that capture to 
researchers. In studies of porbeagle sharks, the recapture and 
reporting rate is approximately 10 percent of tags deployed (Kohler et 
al., 2002; Curtis et al., 2016), meaning that for every 100 porbeagle 
sharks tagged, only 10 are recaptured and reported back to researchers. 
Second, with a conventional tag the researcher only knows the location 
where the animal was tagged and released and where it was recaptured. 
The animal's movement between these two locations is unknown. For 
example, if an animal was tagged/released and later recaptured within a 
few kilometers, we would not know if the animal had stayed in that 
small area for the entire time or if it had traveled thousands of 
kilometers and returned back to the area. Other tags such as pop-up 
satellite archival tags (e.g., PSATs) are attached to the animal and 
store information including location, light level, depth, and 
temperature throughout the tag's deployment period (typically up to 1 
year). The tag then detaches from the animal, floats to the ocean 
surface, and transmits all of the stored data to a satellite; those 
data are used to reconstruct the movements of the animal during 
deployment. This provides more insight into the animal's movements as 
it collects data on a more continuous (daily) basis. These satellite 
tags allow for collection of movement information even if the animal is 
not recaptured.
    Tagging data indicate that porbeagle shark movements across the 
North Atlantic are limited (that is, a limited number of porbeagle 
sharks move across the Atlantic), but do occur (ICES/ICCAT, 2009). One 
porbeagle shark tagged in the Northeast Atlantic was recaptured off 
Newfoundland, Canada; this means that trans-Atlantic movements occur at 
least occasionally (ICES, 2007). The greatest distance documented 
between conventional tag release and recapture location is 4,260 km. 
The time between tagged/released and recapture has been as long as 16.8 
years (N. Kohler, NMFS, unpublished data as reported in Curtis et al., 
2016).
    Several recent studies have used PSATs to track porbeagle sharks in 
the Northwest and Northeast Atlantic and the Southwest Pacific (Pade et 
al., 2008; ICCAT, 2009; Skomal et al., 2009; Campana et al., 2010a; 
Saunders et al., 2011; Bendall et al., 2013; Francis et al., 2015). The 
maximum displacement by a porbeagle recorded with a satellite tag 
(4,400 km) was similar to that documented with conventional tags. 
However, most animals showed relatively restricted movements and 
fidelity to the site where they were tagged, at least within the 
tracking duration (<1 year). This means that while some porbeagle 
sharks make long distance migrations, most animals did not. While the 
data are limited, a few animals have traveled great distances showing 
the biological potential for the species to move between areas. 
Individuals often remain within the range of a particular stock, but 
these data indicate that porbeagle sharks do occasionally move between 
stock areas.
    Mature female porbeagle sharks appear to make the largest movements 
in the Northwest Atlantic. Several sharks tagged off Canada swam 
southward to the subtropical Sargasso Sea and northern Caribbean 
region, presumably to pup (Campana et al.,

[[Page 50467]]

2010a). Males and immature sharks have also made significant movements 
(Saunders et al., 2011; Francis et al., 2015; J. Sulikowski 
(unpublished data) as cited in Curtis et al., 2016). Saunders et al. 
(2011) report that a small male migrated greater than 2,400 km. In a 
study in the Southern Hemisphere, porbeagle sharks made movements of 
hundreds to thousands of kilometers. In this study, an immature male 
shark had the maximum estimated track length (Francis et al., 2015).
    Genetic data can also help define population structure. Though the 
available data from tags indicate little exchange between the Northwest 
and Northeast Atlantic stocks (likely due to the low overall sample 
size), genetic analysis shows these stocks mix (Pade et al., 2006; 
Testerman et al., 2007; ICES/ICCAT, 2009; Kitamura and Matsunaga, 
2010). Mitochondrial DNA (mtDNA) studies indicate that there is no 
differentiation between the stocks within the North Atlantic (Pade et 
al., 2006; Testerman et al., 2007). These studies documented that 
dominant haplotypes were present in samples from both sides of the 
Atlantic, indicating that there is gene flow that is not being 
identified clearly through the tagging studies. Kitamura and Matsunaga 
(2010) also found no indication of multiple populations in the North 
Atlantic based on genetic studies. Similarly, genetic studies in the 
Southern Hemisphere indicate that porbeagle sharks in that region are 
not significantly differentiated (Testerman et al., 2007; Kitamura and 
Matsunaga, 2010). Genetic analyses also suggest no separation between 
the southeastern Indian Ocean and the southwestern Indian Ocean, 
indicating that the distribution across the Indian Ocean is continuous 
(Semba et al., 2013).
    There are several genetic studies that show marked differences 
between the Northern and Southern Hemispheres, supporting the 
conclusions that these populations do not mix (Pade et al., 2006; 
Testerman et al., 2007; ICES/ICCAT, 2009; Kitamura and Matsunaga, 
2010). It is likely that the porbeagle shark's preference for colder 
temperatures limits movement between the hemispheres (Curtis et al., 
2016). If populations are markedly separated and adapted to the 
environment, the differences that occur are shown as they begin to 
diverge genetically. Within the North Atlantic, the data show that they 
are not genetically distinct, that mixing is occurring, and that they 
are not markedly separated. Similarly, the studies within the Southern 
Hemisphere also indicate that these populations are not genetically 
distinct. However, the populations in the Northern Hemisphere are 
markedly separated from those in the Southern Hemisphere.

Abundance and Trends

    As described above, porbeagle sharks are managed for fisheries 
purposes by stock unit. Therefore, much of the data on the abundance of 
populations is by stock. In the North Atlantic, porbeagle sharks have 
declined from 1960s population levels due to overharvesting. However, 
the populations are currently stable or increasing and are on a 
trajectory to recovery (Curtis et al., 2016), meaning that the 
population in the North Atlantic is growing. The North Atlantic stocks 
of porbeagle sharks are considered overfished. In overfished stocks, 
the biomass is well below the biomass at maximum sustainable yield 
(BMSY), which is the abundance level that can support the 
largest, long-term average catch that can be taken under existing 
conditions, and is considered the biomass target for fisheries 
management. Generally, a stock is first considered overfished once 
estimates of biomass are lower than a specific target level. For many 
fish species that target level is one-half BMSY. However, 
generally for sharks, because their natural mortality is so low, the 
target level can be greater than one-half BMSY (e.g., 0.75 
BMSY). In other words, the specific target at which we would 
consider a shark species to be overfished is species-specific and 
depends on that species' level of natural mortality. Once declared 
overfished, a species continues to be considered overfished until 
biomass returns to a different target level. Generally, that level is 
BMSY.
    While porbeagle sharks in the North Atlantic are overfished, 
overfishing is not occurring. (SCRS, 2014; Curtis et al., 2016). 
Overfishing is a level or rate of fishing mortality that jeopardizes 
the long-term capacity of the stock to produce MSY on a continuing 
basis. As explained above, being overfished does not necessarily mean 
that the population is not growing, it is not an indication of 
population trajectory--it just means that biomass is below a target 
level. An overfished stock can be rebuilding and on a trajectory to 
recovery. Overfishing will slow the rate of biomass growth and, if it 
continues, can reverse replenishment and the population will decrease. 
With respect to extinction risk, an overfished marine fish stock may be 
at greater risk than one that is not overfished, but being overfished 
does not automatically equate to a species having an especially high 
risk of extinction (Curtis et al., 2016).
    This means that while the North Atlantic stock sizes are smaller 
than threshold levels (because of fishing or other causes), the annual 
catch rate is at a level that is allowing rebuilding. There is also 
evidence to suggest that the populations in the Southern Hemisphere, 
while overfished, are stable or increasing (ICES/ICCAT, 2009; Pons and 
Domingo, 2010; Francis et al., 2014; WCPFC, 2014).
    Northwest Atlantic--The estimate of the stock of porbeagle sharks 
in the Northwest Atlantic in 1961 is considered to be at an unexploited 
or virgin level. Therefore, this estimate is used for comparison with 
more recent estimates. Several models have assessed porbeagle shark 
abundance, biomass, and trends in the Northwest Atlantic. Different 
types of models have been used, including forward-projecting age and 
sex structured models (DFO, 2005; Campana et al., 2012) and a Bayesian 
Surplus Production (BSP) model (ICES/ICCAT, 2009). These independent 
models came to the same conclusions with respect to the stock size and 
trends (i.e., stock size below target levels, but increasing).
    For 2005, the stock was estimated to be between 188,000 to 195,000 
(DFO, 2005) individuals, 12-24 percent of the 1961 estimates (Gibson 
and Campana, 2005). Campana et al. (2012) modeled the populations from 
the 1961 baseline and projected forward by adding recruitment to the 
population and removing catches. This assessment ran four different 
models using differing assumptions, a routine practice in fisheries 
stock assessment. This method estimated 196,111-206,956 porbeagle 
sharks in 2009 (Campagna et al., 2012), 22-27 percent of the 1961 
estimates. The estimates for 2005 and 2009 can be directly compared 
because the same models and data sources were used in estimating the 
populations. The results indicate that the overall population is 
increasing; even when comparing the low ends of the estimates (188,000 
porbeagle sharks in 2005 compared to 196,111 porbeagle sharks in 2009).
    Campana et al. (2012) also estimated the number of mature females. 
The estimated number of mature females in 2009 ranged from 11,339 to 
14,207 individuals. The estimates of mature females or spawning stock 
biomass are used as indicators of stock health. All four models 
indicated that the number of mature females in the Northwest Atlantic 
stock is increasing and that the 2009 estimates are higher than the 
2005 levels (Campana et al., 2012).
    Furthermore, estimated total biomass (the weight of all porbeagle 
sharks collectively) is also increasing. In 2009,

[[Page 50468]]

total biomass was around 10,000 metric tons (mt), 20-24 percent of the 
1961 estimate. The 2005 assessment did not assess the total biomass. 
However, Campana et al. (2012) did estimate total biomass in 2001. The 
2009 biomass estimate is 4-22 percent higher than the biomass estimated 
from 2001 (Campana et al., 2012; Campana et al., 2010b). Population 
metrics are often expressed in biomass rather than the number of 
individuals, as catch data are reported in weight. An increase in 
biomass is generally indicative of an increase in number of individuals 
(Curtis et. al., 2016) and not just an increase in the weight of the 
same number of individuals. Significantly, all four model variations 
show mean increases in biomass since 2001, confirming the increasing 
biomass estimated in the stock assessment (ICES/ICCAT, 2009). This 
increase likely indicates increased recruitment to the adult stock and 
continued growth of individual fish in the stock (Curtis et al., 2016).
    Maximum likelihoood estimation is a technical, computer-intensive 
statistical approach that allows a researcher to evaluate the 
parameters in a model to identify those with the greatest likelihood of 
having produced the observed (given) data. This statistical analysis 
produces a maximum likelihood value. By iteratively changing the 
parameters in the model until this value is found to be highest 
(maximum), the researcher can identify those parameters most likely to 
have produced the observed data.
    Model runs with different parameters or parameter values will 
result in different maximum likelihood values. Therefore, this approach 
can be used to evaluate a series of models as to which model is the 
preferred model; that is, which model fits the data best. Models with 
higher maximum likelihood values are more likely than those with lower 
values to have produced the observed data. Therefore, models with 
higher maximum likelihood values may be preferred.
    Using this approach, Campana et al. (2012) concluded that Model 1 
was the most plausible model. Model 1 showed increases in the number of 
mature females in the overall populations since 2001, likely reflecting 
the positive effects of management (Campana et al., 2012). Model 2 was 
the least plausible model. Therefore, it is not reasonable to rely on 
Model 2 to assess the population.
    All model variations, except model 2, showed increases in the 
overall population since 2001. Model 2 suggested that there could have 
been slightly fewer fish in 2009 than 2001, but, as noted above, based 
on the maximum likelihood method, the researchers identified this model 
variation as the ``least plausible'' variation and indicated that it is 
not likely an indicator of the true trend in the population (Campana et 
al., 2010b; Campana et al., 2012). Because of this, it is not 
reasonable to rely on Model 2. The overall agreement of all modeled 
population trends provides strong evidence of increasing abundance in 
this stock (Campana et al., 2012).
    Similarly, all four model variations show increases in female stock 
numbers and three of the four show increases in general populations 
from 2005-2009. Again, model 2 was the exception. This model estimated 
a slight decrease (approximately two percent or 4,000 fish) in the 
overall population from 2005 to 2009. As mentioned, this model was 
determined to be the ``least plausible'' (Campana et al., 2012). Even 
if the more conservative model 2 (a lower productivity scenario) more 
closely reflected the reality of porbeagle stock size, the stock was 
still projected to increase under the current harvest levels (Campana 
et al., 2012). Based on the four model runs and taking into account the 
most plausible scenarios as defined by the researchers, the reasonable 
conclusion is that biomass and the general population has increased 
since 2001 and will continue to increase in the future (Curtis et al., 
2016).
    The models used by Campana et al. (2010, 2012) were forward 
projecting age- and sex-based models. These models projected the 
population forward in time from an equilibrium starting abundance 
(i.e., the unfished population in 1961) and age distribution by adding 
recruitment and removing catches. The models assessed both the female 
population and total population.
    In 2009, the ICES/ICCAT stock assessment working group ran a BSP 
model for the Northwest Atlantic stock, which was considered in 
addition to the forward projecting age- and sex-based model from 
Campana et al. (2010). The BSP model was used to confirm the trends 
from the results of Campana's age-structured model. The Campana et al. 
(2010) model and the BSP model are based on different assumptions as to 
how the data should be interpreted and weighted and, therefore, result 
in differing estimates. The BSP model used catch per unit effort (CPUE) 
to estimate biomass and weighted the CPUE data using two approaches 
resulting in two variations of the model. CPUE data in the catch-
weighted model were weighted by relative proportion of the catch 
corresponding to each CPUE series in each year (catch-weighted model; 
meaning that annual data with more catch had a greater influence on the 
model output). The equal-weighted BSP considered eight CPUE series; six 
Canadian CPUE series, the U.S. series, and the Spanish series (limited 
to two areas). Each point in each data series was given equal weight 
(equal weighted model; meaning that the relative amount of catch in 
each annual point had no influence on the model output). Thus the 
Canadian series, which has the majority of the catch, was effectively 
given more weight than the United States or Spanish series. The catch-
weighted BSP model estimated the biomass in 2005 to be 66 percent of 
the 1961 biomass. The equal weighted BSP model estimated the biomass in 
2005 as 37 percent of the 1961 biomass. Both models resulted in 
estimates higher than the estimate of 10-24 percent from the Campana et 
al. (2010) age-structured model. Results of the BSP model applied to 
data through 2009 were similar to those of the age-structured model, 
providing further support that Model 2 (Campana et al., 2012) is less 
reliable. Because the two independent models came to the same 
conclusions with respect to the stock size and trends (i.e., stock size 
below target levels, but increasing), we have confidence in the 
determination that the stock has increased.
    The ICES/ICCAT (2009) working group looked at all available models, 
data, and fits to the data. They determined that, in recent years, 
total biomass is increasing and fishing mortality is decreasing. This 
indicates that the Northwest Atlantic stock is recovering. These 
results are supported by more recent assessments (Campana et al., 2010; 
Campana et al., 2012; SCRS, 2014). In summary, recent biomass and 
abundance appears to be increasing under all available models. While 
the population is overfished, overfishing is not occurring.
    Northeast Atlantic--This stock has the longest history of being 
targeted by commercial fishing. The highest catches occurred between 
the 1930s and 1950s (ICES/ICCAT, 2009). The lack of CPUE data during 
the peak of the fishery makes it difficult to estimate current status 
relative to biomass of an unfished stock. The ICCAT stock assessment 
working group ran various model scenarios to assess the Northeast 
Atlantic stock of porbeagle sharks. The working group found that the 
stock was overfished but that overfishing was not occurring and that 
current management was likely to prevent the stock from declining 
further and allow recovery (ICES/ICCAT, 2009). The working group

[[Page 50469]]

indicated that the stock would recover within 15-34 years (one to two 
generations) if there was no fishing mortality (ICES/ICCAT, 2009). 
Under the 2009 European Union (EU) total allowable catch (TAC) level, 
the stock was projected to increase slowly but not rebuild (i.e., reach 
a target population size that supports maximum sustainable yield) 
within 50 years. The TAC is the amount of the species allowed to be 
harvested by all users, commercial and recreational, over a specified 
time. In 2010, the TAC was set at zero and has remained at zero; 
therefore, it is reasonable to assume that at the current fishing 
levels the stock will continue to increase and rebuild.
    Porbeagle sharks from the Northeast Atlantic stock are also found 
in the Mediterranean Sea. The Mediterranean Sea is in the southeastern 
edge of the porbeagle shark's range in the North Atlantic, and the 
species has always been uncommon in the region (Storai et al., 2005; 
CITES, 2013). There is no information suggesting that porbeagle sharks 
in the Mediterranean Sea are isolated genetically or spatially from the 
larger Northeast Atlantic stock. Given that porbeagle sharks are highly 
mobile and habitat generalists, the animals in the Mediterranean Sea 
are likely to mix with animals in adjacent regions. Ferretti et al. 
(2008) examined various historical data sources, some of which dated 
back to 1800s, from the Mediterranean Sea and estimated that lamnid 
sharks (including porbeagle and shortfin mako sharks) had declined 
significantly from historical levels. The researchers were unable to 
distinguish what portion of the decline is attributable to porbeagle 
sharks. Porbeagle sharks have had a low occurrence and catch rate in 
this region even at the earliest stages of the time series (Ferretti et 
al., 2008). This research was based on small overall sample sizes and 
used methods that have been previously criticized as producing overly 
pessimistic population trends (Burgess et al., 2005). Storai et al. 
(2005) were only able to document 33 verified records of porbeagle 
sharks around Italy from 1871-2004, confirming that these sharks have 
had a low historical occurrence. Other data sources also show low 
historical occurrence throughout the Mediterranean Sea (CITES, 2013). 
The ERA team concluded that porbeagle abundance has possibly declined 
in the Mediterranean Sea, but the species is historically uncommon in 
this region (Curtis et al., 2016).
    Southern Hemisphere--Data on porbeagle sharks in the Southern 
Hemisphere are sparse. This limits the ability to provide a robust 
indication of the stock status and sustainable harvest levels. However, 
there is some information available. The 2009 ICES/ICCAT working group 
found that the available data, from the Uruguayan longline fleet 
operating between 1982 and 2008, indicate a long-term decline in CPUE 
in the Uruguayan fleet, meaning that fewer porbeagle sharks were being 
caught with the same amount of effort in 2008 compared to 1982. The 
data indicate that the CPUE has stabilized since 2000 (ICES/ICCAT, 
2009). In a modeling effort, they concluded that biomass levels may be 
below BMSY and that fishing mortality rates may be above 
those producing MSY (i.e., overfishing may be occurring). Pons and 
Domingo (2010) also evaluated the CPUE using data from 1982-2008. They 
found declines in CPUE in the Uruguayan fleet during the 1990s, but 
that the trend has been stable or slightly increasing since 2000. In 
2013, Uruguay prohibited retention of porbeagle sharks. The Standing 
Committee on Research and Statistics (SCRS, 2014) determined that the 
Southwest Atlantic stock was overfished but overfishing was probably 
not occurring. While data in the Southeast Atlantic was too limited to 
assess whether porbeagle stocks were overfished or if overfishing was 
occurring (ICES/ICCAT, 2009; SCRS, 2014), catch rate patterns suggest 
that this stock has stabilized since 2000 and is no longer declining 
(ICES/ICCAT, 2009; Pons and Domingo, 2010).
    Semba et al. (2013) analyzed porbeagle sharks in the Southern 
Hemisphere using standardized CPUE data from the southern Bluefin Tuna 
longline fishery (1994-2011) and a driftnet survey (1982-1990). The 
study found no decreasing trend in abundance and concluded porbeagle 
sharks had a widely continuous distribution between the South Pacific 
and southeastern Indian Ocean and between the southwestern Indian Ocean 
and southeastern Atlantic Ocean. They also determined that juvenile 
abundance had not changed greatly during the period of 1982 to 2011. 
Due to a lack of fishing effort in the Indian Ocean, the study was 
unable to confirm presence in the central South Indian ocean but noted 
that genetic data indicate that the distribution is likely continuous 
through the Indian Ocean (Semba et al., 2013).
    There are no abundance trend data for porbeagle sharks in 
Australian waters. Historically, Japanese longline vessels operating in 
Australian waters caught porbeagle sharks, but these vessels have been 
excluded from these waters since 1997 and domestic Australian fishing 
effort is greatly reduced in areas where porbeagle sharks were caught 
(Bruce et al., 2014). Porbeagle sharks are also caught incidentally in 
New Zealand's Southern Bluefin Tuna longline fishery. In New Zealand 
waters in recent years, stock status indices showed no sign of 
declining trends in abundance (Francis et al., 2014; WCPFC, 2014). The 
CPUE indices were stable or increasing and the frequency of zero 
catches in the fishery declined, suggesting increases in relative 
abundance since 2005.
    The level of diversity in genetic samples can also be an indicator 
of the population size. Mitochondrial DNA from samples in the North and 
South Atlantic show high diversity, indicative of a large population. 
Porbeagle sharks are the third most dominant species in the sub-
Antarctic region of the South Pacific and are common throughout the 
Southern Hemisphere (Semba et al., 2013).
    In summary, stocks in the North Atlantic have stabilized and appear 
to be increasing. The Southwest Atlantic stock is considered overfished 
but overfishing is not occurring. Information on the Southeast Atlantic 
stock is too limited to determine the overfished/overfishing status, 
but it has been stable and not declining since the 1990s (ICES/ICCAT, 
2009; SCRS, 2014). Populations in New Zealand also appear to be 
increasing (Francis et al., 2014; WCPFC, 2014). Stocks in the Southern 
Hemisphere have stabilized and some may be increasing.

Distinct Population Segment Analysis

    As described above, the ESA's definition of ``species'' includes 
``any subspecies of fish or wildlife or plants, and any distinct 
population segment of any species of vertebrate fish or wildlife which 
interbreeds when mature.'' The term ``distinct population segment'' is 
not recognized in the scientific literature and is not clarified in the 
ESA or its implementing regulations. Therefore, the Services adopted a 
joint policy for recognizing DPSs under the ESA (DPS Policy; 61 FR 
4722) on February 7, 1996. Congress has instructed the Secretaries of 
Interior and Commerce to exercise this authority with regard to DPSs 
``* * * sparingly and only when biological evidence indicates such an 
action is warranted.'' The DPS Policy requires the consideration of two 
elements when evaluating whether a vertebrate population segment 
qualifies as a DPS under the ESA: (1) The discreteness of the 
population segment in relation to the remainder of the species or 
subspecies to which it belongs; and (2)

[[Page 50470]]

the significance of the population segment to the species or subspecies 
to which it belongs.
    A population segment of a vertebrate species may be discrete if it 
satisfies either one of the following conditions: (1) It is markedly 
separated from other populations of the same taxon (an organism or 
group of organisms) as a result of physical, ecological, or behavioral 
factors. Quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation; or (2) it is 
delimited by international governmental boundaries within which 
differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the ESA (e.g., inadequate 
regulatory mechanisms). If a population segment is found to be discrete 
under one or both of the above conditions, its biological and 
ecological significance to the taxon to which it belongs is evaluated. 
This consideration may include, but is not limited to: (1) Persistence 
of the discrete population segment in an ecological setting unusual or 
unique for the taxon; (2) evidence that loss of the discrete population 
segment would result in a significant gap in the range of a taxon; (3) 
evidence that the discrete population segment represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range; or 
(4) evidence that the discrete population segment differs markedly from 
other population segments of the species in its genetic 
characteristics.
    The petition from Wild Earth Guardians requested that we list 
porbeagle sharks throughout their entire range, or as Northwest 
Atlantic, Northeast Atlantic, and Mediterranean Distinct Populations 
Segments (DPS) under the ESA, and that we designate critical habitat 
for the species. The petition from the HSUS requested we list a 
Northwest Atlantic DPS of porbeagle shark as endangered.
    In the Status Review, the ERA team considered the available 
information to assess whether there are any porbeagle population 
segments that satisfy the DPS criteria of both discreteness and 
significance. Rather than limit the analysis to only the potential DPSs 
identified by the petitioners, the ERA team considered whether any DPSs 
could be determined for porbeagle sharks. Data relevant to the 
discreteness question included physical, ecological, behavioral, 
tagging, and genetic data. As described above, porbeagle sharks occur 
in the North Atlantic and in a continuous band around the Southern 
Hemisphere. They are absent from equatorial waters. Recent assessments 
have identified four stocks: The Northwest, Northeast, Southwest, and 
Southeast Atlantic stocks for fishery management purposes. An 
additional Indo-Pacific stock may also be present, but Southern 
Hemisphere stock boundaries are unclear (CITES, 2013).
    The population in the North Atlantic is separated from the 
population in the Southern Hemisphere, as porbeagle sharks are absent 
from equatorial waters. It is likely that their preference for colder 
water temperatures limits movement between the Northern and Southern 
Hemispheres. The genetic data support that they do not move between 
these hemispheres, as genetic studies show marked differences between 
the populations in the North Atlantic and the Southern Hemisphere. This 
indicates that porbeagle sharks in the North Atlantic and porbeagle 
sharks in the Southern Hemisphere do not interbreed (Padre et al., 
2006; Testerman et al., 2007; ICES/ICCAT, 2009; Kitamura and Matsunaga, 
2010). Porbeagle sharks in the Southern Hemisphere are also 
biologically different. In the Southern Hemisphere, porbeagle sharks 
are smaller, slower growing, mature at a smaller size and greater age, 
and may be longer lived than those in the North Atlantic (Francis et 
al., 2007, 2008, 2015). The ERA team concluded, and we concur, that the 
North Atlantic and Southern Hemisphere populations are discrete.
    There is no information indicating that porbeagle sharks in the 
Mediterranean Sea, where they are historically rare, are isolated from 
the Northeast Atlantic stock. There are no direct genetic or tagging 
data on porbeagle sharks in the Mediterranean Sea, but numerous other 
highly migratory species (tunas, sharks) are known to move in and out 
of the Mediterranean Sea. Given that porbeagle sharks are widely 
distributed and highly migratory, it is reasonable to expect that 
porbeagle sharks in the Mediterranean Sea would mix with porbeagle 
sharks in other parts of the Northeast Atlantic. There is no 
information to indicate that porbeagle sharks in the Mediterranean Sea 
are a discrete population. As there is no evidence that the 
Mediterranean Sea population of porbeagle sharks is discrete, it was 
considered as part of the Northeast Atlantic stock for the remainder of 
the analysis.
    Both tagging and genetic data can provide insight into whether a 
population is discrete. Conventional and satellite tagging data suggest 
limited, but occasional movements of porbeagle sharks between the 
Northwest and Northeast Atlantic, as well as long distance movements 
into subtropical latitudes of the North Atlantic (Kohler et al., 2002; 
Pade et al., 2008; ICCAT, 2009; Skomal et al., 2009; Campana et al., 
2010a; Saunders et al., 2011; Bendall et al., 2013). As described 
above, using conventional tagging data to inform our understanding of 
the animal's movements is limited by the frequency of recapture/return 
of tags and by the limited data returned. Though the tagging data offer 
little evidence of mixing between the Northwest and Northeast Atlantic, 
the genetic analyses show that these populations do mix. Mitochondrial 
DNA studies indicate that there is no differentiation among the stocks 
in the North Atlantic. The stocks are indistinguishable genetically, 
indicating that there is mixing and gene flow between them (Pade et 
al., 2006; Testerman et al., 2007). This level of mixing is occurring 
at a rate that has prevented the species from becoming genetically 
differentiated, meaning that there is enough interbreeding between 
porbeagle sharks in the Northwest and Northeast Atlantic that the 
populations are not significantly different genetically. Genetic 
homogeneity across broad regions can be achieved with extremely low 
mixing rates, even one percent per generation (Ward 2000). While the 
mixing rates between the Northwest and Northeast North Atlantic may be 
low, these populations mix sufficiently that there is a lack of genetic 
differentiation between the stocks. Curtis et al. (2016) hypothesize 
two pathways by which these movements may occur: (1) Active emigration 
or vagrancy of mature females from one subpopulation to a neighboring 
one or (2) a lack of philopatry in porbeagle pups born in subtropical 
waters (i.e., not all porbeagle sharks return to their birthplace to 
breed). For example, pups born from Northwest Atlantic mothers may move 
into the Northeast Atlantic as they mature. More tagging and genetic 
studies are needed to determine the pathway and to better assess mixing 
rates (Curtis et al., 2016); however, the current available evidence 
indicates that porbeagle sharks in the Northeast and Northwest Atlantic 
are not discrete.
    In the North Atlantic, the porbeagle shark does cross international 
governmental boundaries. There are regulatory mechanisms in place 
across the species' range with respect to conserving and recovering 
porbeagle stocks. Similar regulatory mechanisms have been implemented 
on both sides of the Atlantic. These mechanisms include regulating 
directed catch and bycatch

[[Page 50471]]

and are described further below. Given the lack of genetic 
differentiation between the North Atlantic stocks and the lack of 
significant differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms across 
international borders, we have determined that the two stocks in the 
North Atlantic are not discrete from one another.
    Tagging data in the Southern Hemisphere are very limited. Porbeagle 
sharks have a continuous distribution throughout the Southern 
Hemisphere (Semba et al., 2013). As described above, Southwest and 
Southeast Atlantic stocks have been defined for management purposes, 
and there may also be an Indo-Pacific stock (including Australia, New 
Zealand, and the greater Southwest Pacific). Potential stock boundaries 
have been difficult to define and remain unclear (CITES, 2013). The 
available genetics data have not revealed any clear differentiation 
among samples throughout the region (Pade et al., 2006; Testerman et 
al., 2007; Kitamura and Matsunaga, 2010). Similar to the North 
Atlantic, porbeagle sharks in the Southern Hemisphere cross 
jurisdictional boundaries. As described below, regulatory measures 
restricting harvest are also in place across the range of this 
population. There is no information indicating that the populations in 
the Southern Hemisphere are discrete from one another. Therefore, there 
is no information to indicate there are separate DPSs in the Southern 
Hemisphere. Based on the best available information, the ERA team 
concluded that that there are two discrete populations; one in the 
North Atlantic and the other in the Southern Hemisphere.
    In accordance with the DPS policy, the ERA team also reviewed 
whether these two population segments identified in the discreteness 
analysis were significant. If a population segment is considered 
discrete, its biological and ecological significance relative to the 
species or subspecies must then be considered. We must consider 
available scientific evidence of the discrete segment's importance to 
the taxon to which it belongs. Data relevant to the significance 
question include morphological, ecological, behavioral, and genetic 
data, as described above. The ERA team found that the loss of either 
population segment would result in a significant gap in the range of 
the taxon and, therefore, both were significant. We considered the 
information presented in the status review and the following factors, 
identified in the DPS policy, which can inform the significance 
determination: (a) Persistence of the discrete segment in an ecological 
setting unusual or unique for the taxon; (b) evidence that loss of the 
discrete segment would result in a significant gap in the range of the 
taxon; (c) evidence that the discrete segment represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range; and 
(d) evidence that the discrete segment differs markedly from other 
populations of the species in its genetic characteristics. A discrete 
population segment needs to satisfy only one of these criteria to be 
considered significant.
    The range of each discrete population (i.e., the North Atlantic and 
Southern Hemisphere populations) represents a large portion of the 
species' range, as well as a unique ecosystem that has influenced the 
population. The North Atlantic and Southern Hemisphere ecosystems are 
unique with different physical (e.g., currents), chemical (e.g., 
salinity), and biological (e.g., species size, longevity) properties. 
Each population is in a separate hemisphere, and the loss of either 
segment would result in a significant gap in the range of the species. 
That is, if the North Atlantic population were extirpated, the only 
porbeagle sharks would be in the Southern Hemisphere. As porbeagle 
sharks do not move between hemispheres and equatorial waters are too 
warm to support the species, it is not reasonable to expect that 
porbeagle sharks would move from the Southern Hemisphere into the North 
Atlantic, and the result would be a significant gap in the range of the 
species. In evaluating the factors above, factors a and b indicate that 
the two discrete population segments are significant. Therefore, we 
concur with the ERA team that the two discrete population segments are 
also significant. As such, we are identifying two DPSs of porbeagle 
shark. The extinction risk to the North Atlantic and Southern 
Hemisphere DPSs was evaluated separately for each DPS.

Assessment of Extinction Risk

    The ESA (Section 3) defines endangered species as ``any species 
which is in danger of extinction throughout all or a significant 
portion of its range.'' A threatened species is ``any species which is 
likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range.'' Neither we nor 
the USFWS have developed any formal policy guidance about how to 
further define the thresholds for when a species is endangered or 
threatened. We consider the best available information and apply 
professional judgment in evaluating the level of risk faced by a 
species in deciding whether the species is currently in danger of 
extinction throughout all or in a significant portion of its range 
(endangered) or likely to become so in the foreseeable future 
(threatened). We evaluate both demographic risks, such as low abundance 
and productivity, and threats to the species, including those related 
to the factors specified by the ESA Section 4(a)(1)(A)-(E).

Methods

    As described above, we convened an ERA team to evaluate extinction 
risk to the species. This section discusses the methods used to 
evaluate demographic factors, threats, and overall extinction risk to 
the species now and in the foreseeable future. For this assessment, the 
term ``foreseeable future'' was defined as two generation times (40 
years), consistent with other recent assessments for shark species. A 
generation time is defined as the time it takes, on average, for a 
sexually mature female porbeagle shark to be replaced by offspring with 
the same spawning capacity. As a late-maturing species, with slow 
growth rate and relatively low productivity, it would likely take more 
than a generation time for conservative management actions to be 
realized and reflected in population abundance indices. The ERA team 
reviewed other comparable assessments (which used generation times of 
either one or two generations) and discussed the appropriate timeframe 
for porbeagle sharks. The ERA team determined that, for porbeagle 
sharks, there was reasonable confidence across this time period (40 
years) that the information on threats and management is accurate.
    Often the ability to measure or document risk factors is limited, 
and information is not quantitative or very often lacking altogether. 
Therefore, in assessing risk, it is important to include both 
qualitative and quantitative information. In previous NMFS' status 
reviews, Biological Review Teams have used a risk matrix method, 
described in detail by Wainwright and Kope (1999), to organize and 
summarize the professional judgement of a panel of knowledgeable 
scientists. The approach of considering demographic risk factors to 
help frame the consideration of extinction risk has been used in many 
of our status reviews (see https://www.nmfs.noaa.gov/pr/species for 
links to these reviews). In this approach, the collective condition of 
individual

[[Page 50472]]

populations is considered at the species level according to four 
demographic viability factors: Abundance, growth rate/productivity, 
spatial structure/connectivity, and diversity. Connectivity refers to 
rates of exchange among populations of organisms. These viability 
factors reflect concepts that are well-founded in conservation biology 
and that individually and collectively provide strong indicators of 
extinction risk.
    Using these concepts, the ERA team evaluated demographic risks by 
individually assigning a risk score to each of the four demographic 
criteria (abundance, growth rate/productivity, spatial structure/
connectivity, diversity). The scoring for the demographic risk criteria 
correspond to the following values: 1--very low, 2--low, 3--medium, 4--
high, and 5--very high. A demographic factor was ranked very low if it 
is very unlikely the factor contributes or will contribute 
significantly to the risk of extinction. A factor was ranked low if it 
is unlikely it contributes or will contribute significantly to the risk 
of extinction. A factor was ranked medium if it is likely it 
contributes to or will contribute significantly to the risk of 
extinction. A factor was ranked high if it is highly likely that it 
contributes or will contribute significantly to the risk of extinction, 
and a factor was ranked very high if it is very highly (extremely) 
likely that the factor contributes or will contribute significantly to 
the risk of extinction.
    Each team member scored each demographic factor individually. Each 
team member identified other demographic factors and/or threats that 
would work in combination with factors ranked in the higher categories 
to increase risk to the species. After scores were provided, the team 
discussed the range of perspectives and the supporting data for these 
perspectives. Team members were given the opportunity to adjust the 
scores, if desired, after discussion. The scores were then tallied, 
reviewed, and considered in the overall risk determination. As noted 
above, this scoring was carried out for each of the two identified 
DPSs.
    The ERA team also performed a threats assessment for the porbeagle 
shark by evaluating the impact that a particular threat was currently 
having on the extinction risk of the species. Threats considered 
included habitat destruction, modification, or curtailment; 
overutilization; disease or predation; inadequacy of existing 
regulatory mechanisms; and other natural or manmade threats, because 
these are the five factors identified in Section 4(a)(1) of the ESA. 
The scoring for the threats correspond to the following values: 1--very 
low, 2--low, 3--medium, 4--high, and 5--very high. A threat was given a 
rank of very low if it is very unlikely that the particular threat 
contributes or will contribute to the decline of the species. That is, 
it is very unlikely that the threat will have population-level impacts 
that reduce the viability of the species. A threat was ranked as low if 
it was unlikely the threat contributes or will contribute to the 
decline of the species. A threat was ranked as medium if it was likely 
that it contributes or will contribute to the decline of the species 
and high if it highly likely that it contributes or will contribute to 
the decline of the species. A threat was given a rank of very high if 
it was very highly (extremely) likely that the particular threat 
contributes or will contribute to the decline of the species. Detailed 
definitions of the risk scores can be found in the status review 
report. Similar to the demographic parameters, the ERA team was asked 
to identify other threat(s) and/or demographic factor(s) that may 
interact to increase the species extinction risk. The ERA team also 
considered the ranking with respect to the interactions with other 
factors and threats. For example, team members identified that threats 
due to the inadequacy of existing regulatory mechanisms may interact 
with the threat of overutilization and slow population growth rates (a 
demographic factor) to increase the risk extinction. When potential 
interactions such as these were identified, the team then evaluated 
those interactions (in this case interactions between the regulatory 
mechanisms, overutilization, and growth rates) to determine whether 
they would significantly change the ranking of the threat (in this case 
inadequacy of regulatory mechanisms). Team members again discussed 
their rankings and the supporting data and were given a chance to 
revise scores based on the discussion. These scores were considered 
with the demographic scores in the overall risk assessment.
    The ERA team members were then asked to use their informed 
professional judgment to make an overall extinction risk determination 
for the porbeagle shark. The results of the demographic risks analysis 
and threats assessment, described below, informed this ranking. For 
this analysis, the ERA team defined four levels of extinction risk: Not 
at risk, low risk, moderate risk, and high risk. A species is at high 
risk of extinction when it is at or near a level of abundance, spatial 
structure and connectivity, and/or diversity and resilience that place 
its persistence in question. Demographic risk may be strongly 
influenced by stochastic (random events or processes that may affect 
the population) or depensatory (resulting from a depressed breeding 
population) processes. Similarly, a species may be at high risk of 
extinction if it faces clear and present threats (e.g., confinement to 
a small geographic area, imminent destruction, modification, or 
curtailment of habitat; or disease epidemic) that are likely to create 
imminent demographic risks (e.g., low abundance, genetic diversity, 
resilience). A species is at moderate risk of extinction due to 
projected threats and its likely response to those threats (i.e., 
declining trends in abundance/population growth, spatial structure and 
connectivity, and/or diversity and resilience) if it exhibits a 
trajectory indicating that it is more likely not to be at a high level 
of extinction. A species is at low risk of extinction due to projected 
threats and its likely response to those threats (i.e., stable or 
increasing trends in abundance/population growth, spatial structure and 
connectivity, and/or diversity and resilience) if it exhibits a 
trajectory indicating it is not at moderate level of extinction risk. 
Lastly, a species is not at risk of extinction due to projected threats 
and its response to those threats (i.e., long-term stability, 
increasing trends in abundance/population growth, spatial structure and 
connectivity, and/or diversity and resilience) if it exhibits a 
trajectory indicating that it is not at a low risk of extinction.
    The ERA team adopted the ``likelihood point'' method for ranking 
the overall risk of extinction to allow individual team members to 
express uncertainty. For this approach, each team member distributed 10 
`likelihood points' among the extinction risk categories (that is, each 
team member had 10 points to distribute among the four extinction risk 
categories). Uncertainty is expressed by assigning points to different 
risk categories. For example, a team member would assign all 10 points 
to the `not at risk' category if he/she was certain that the definition 
for `not at risk' was met. However, he/she might assign a small number 
of points to the `low risk' category and the majority to the `not at 
risk' category if there was a low level of uncertainty regarding the 
risk level. The more points assigned to one particular category, the 
higher the level of certainty. This approach has been used in previous 
NMFS status reviews (e.g., Pacific salmon, Southern Resident killer 
whale, Puget Sound rockfish, Pacific herring,

[[Page 50473]]

black abalone, and common thresher shark) to structure the team's 
thinking and express levels of uncertainty when assigning risk 
categories. Although this process helps to integrate and summarize a 
large amount of diverse information, there is no simple way to 
translate the risk matrix scores directly into a determination of 
overall extinction risk. The team scores were tallied (mode, median, 
range), discussed, and summarized for each DPS.
    The ERA team did not make recommendations as to whether the species 
should be listed as threatened or endangered. Rather, the ERA team drew 
scientific conclusions about the overall risk of extinction faced by 
the North Atlantic and Southern Hemisphere populations of porbeagle 
shark under present conditions and in the foreseeable future (as noted 
above, defined as two generation times or 40 years) based on an 
evaluation of the species' demographic risks and assessment of threats.

Evaluation of Demographic Risks

    Abundance: The ERA team evaluated the available information on 
population abundance and trends. They concluded that a ranking of low 
was warranted for both DPSs, as this factor is unlikely to contribute 
significantly to the porbeagle shark's risk of extinction. Kitamura and 
Matsunaga (2010) analyzed mtDNA from sharks in the North and South 
Atlantic. The research found high genetic diversity, indicative of a 
large population. Campana et al. (2012) reports that the large 
population size of the porbeagle shark in the Northwest Atlantic should 
make it such that random factors would not pose a major risk to the 
species. The ERA team concluded that the best available information 
does not indicate a decrease in the productivity of the porbeagle shark 
and that both DPSs exhibit significant diversity indicative of large 
populations (Curtis et al., 2016).
    Both DPSs have declined significantly from historical levels. In 
the North Atlantic, these declines appear to have been halted and the 
DPS' abundance and biomass are increasing (ICES/ICCAT, 2009; Campana et 
al., 2010b; Campana et al., 2012). Further declines are unlikely due to 
improved and continuing management. As described in the status review, 
the North Atlantic population is overfished, but overfishing is not 
occurring (Curtis et al., 2016). Estimates of the population size are 
in the hundreds of thousands of individuals for just the Northwest 
Atlantic portion of the DPS (DFO, 2005; Camapana et al., 2010, 2012). 
The population abundance and trends of porbeagle sharks throughout the 
Southern Hemisphere are stable or increasing. The declines in the 
Southern Hemisphere appear to be halted and, in some regions, the 
abundance has increased in recent years (ICES/ICCAT, 2009; Pons and 
Domingo, 2010; Semba et al., 2013; Francis et al., 2014; WCPFC, 2014; 
Curtis et al., 2016).
    Targeted removal from a population can result in a population 
structure (e.g., size and sex composition) that has been modified from 
unfished conditions. If fisheries remove certain age classes or sexes 
(e.g., selectively target the largest individuals in the population), 
the structure of the population will be modified. Porbeagle sharks are 
overfished and, therefore, it is likely the population structure (e.g., 
the number of large females) has been reduced, resulting in a truncated 
size/age distribution. However, declines have been halted, and stocks 
are rebuilding. As the stocks rebuild, the population structure will 
return to its more natural state with a robust size/age composition.
    Growth rate/productivity: The ERA team evaluated the information 
available on the porbeagle shark's growth rate/productivity. They 
determined that this is a medium risk factor for both DPSs. Life 
history characteristics of late age to maturity, low fecundity, slow 
population growth rates, and long generation time contribute to low 
productivity in porbeagle sharks. These characteristics make both DPSs 
vulnerable to overexploitation and slow to recover from depletion. This 
vulnerability is characteristic of species with this type of life 
history.
    Spatial structure/connectivity: The ERA team evaluated the 
porbeagle shark's spatial structure and connectivity (i.e., rates of 
exchange among populations). They concluded that this factor is very 
unlikely to contribute to the risk of extinction for either the North 
Atlantic or Southern Hemisphere DPS. While there is not mixing across 
the equator, tagging studies show that the species is highly mobile, 
and there are movements over long distances within the North Atlantic 
and the Southern Hemisphere. Genetic studies show that within each DPS, 
mixing occurs, and there is connectivity within each of the two DPSs. 
There is no evidence of isolation of any stock within either DPS. There 
is also no evidence that the range of the species has contracted over 
time or is likely to contract in the future (Curtis et al., 2016). The 
ERA team ranked this factor as very low.
    Diversity: The ERA team also evaluated the diversity within both 
DPSs. They concluded that this is a very low risk factor because 
diversity is high within each DPS. Genetic studies indicate high 
diversity in both DPSs, and there is connectivity across the ocean 
basins. The high genetic diversity indicates that, within hemispheres, 
the populations are not isolated. Significant differentiation within 
either DPS has not been identified, meaning that while diversity is 
high within each DPS (indicative of a large population), each stock 
within a DPS has similar genetics that are not distinct. The species 
does not appear to be at risk due to substantial changes or loss of 
variation in life history characteristics, population demography, 
morphology, behavior, or genetic characteristics.

Evaluation of Threats

    Habitat Destruction, Modification, or Curtailment: The ERA team 
ranked this threat as very low for both DPSs. As described above, 
porbeagle sharks are highly mobile generalists. That is, they are not 
substantially dependent on any particular habitat type. Occurring in 
coastal and offshore waters, this shark is not dependent during any 
life stage on more vulnerable estuarine habitats, and there are no 
indications that its range has contracted or is expected to contract in 
the future (Curtis et al., 2016). While their distribution is 
influenced by temperature and prey distributions, they have broad 
temperature tolerances (1-26 [deg]C) and an opportunistic diet, feeding 
on a wide range of species, depending on what is available (Joyce et 
al., 2002). Both factors make them less vulnerable to impacts from 
habitat changes.
    The literature review found no information to indicate that there 
has been a change in distribution of porbeagle sharks due to climate 
change or that porbeagle sharks would be unable to adapt to potential 
changes in prey distribution. Changes in temperature in the range of 
those predicted under various climate scenarios (Hare et al., 2016) are 
unlikely to have a significant impact on porbeagle sharks (Curtis et 
al., 2016). Fabry et al., (2008) indicate that increases in carbon 
dioxide (CO2) have the potential to affect pH levels in 
marine animals. Active animals have a higher capacity for buffering pH 
changes, and the tolerance of CO2 by marine fish appears to 
be very high (Fabry et al., 2008). Porbeagle sharks are an active and 
highly mobile species. Therefore, it is reasonable to expect that 
porbeagle sharks will tolerate changes in CO2 and buffer pH 
(Compagno, 2001; Fabry et al., 2008; Curtis et al., 2016).

[[Page 50474]]

As detailed in the status review, they also appear to have low exposure 
to pollution and do not appear to be threatened by it. The National 
Shark Research Consortium (2007) determined that it was unlikely that 
infertility rates were associated with contaminant exposure. The 
available information indicates that the fitness of porbeagle sharks is 
not likely to be negatively impacted by mercury or other contaminants 
to any significant degree (Curtis et al., 2016). Therefore, this threat 
is considered to be very low to both the North Atlantic and Southern 
Hemisphere DPSs.
    Overutilization: Overutilization was ranked as medium in the 
threats assessment by each member of the ERA team. In evaluating the 
status of the species, Curtis et al. (2016) reviewed population 
dynamics, including population size, abundance trends, recruitment and 
depensation, and the effects of trade as most shark landings enter 
international trade. Porbeagle sharks have historically been fished 
commercially, and overutilization is considered the primary threat to 
porbeagle shark populations. They have primarily been harvested 
incidentally in longline fisheries targeting other highly migratory 
species. Incidental harvest occurs when the species is caught in a 
fishery targeting other species. Directed fisheries for porbeagle 
sharks have occurred in Canada, France, Norway, Faroe Islands, and 
Uruguay (Curtis et al., 2016). Porbeagle stocks are overfished. Being 
overfished is not, by itself, equivalent to having a high risk of 
extinction. Currently, overfishing is not occurring and populations of 
porbeagle sharks appear to be stable or increasing, and further 
declines are considered unlikely, given conservation and management 
measures. Declines in catch in recent years are largely due to greater 
regulatory controls, especially in nations that had directed fisheries 
(DFO, 2005; ICCAT, 2009).
    In the United States, commercial fishermen can land porbeagle under 
a directed or incidental shark permit. In the past, most porbeagle 
sharks have been landed via pelagic longline, but there have also been 
some incidental landings in Gulf of Maine fisheries targeting other 
species. According to logbook data, pelagic longline fishermen have not 
reported landing any porbeagle sharks in the last few years (2013-2015) 
and reported landing only between 3 and 23 sharks each year from 2010 
through 2012 (NMFS, unpublished data). The majority of porbeagle sharks 
caught by pelagic longline fishermen from 2010 through 2015 were 
released alive (on average 78 percent per year). There are strict 
regulations in the pelagic longline fishery including restrictions on 
hook size, hook type, and bait type. There are no mesh restrictions in 
the shark gillnet fishery under the management plan for highly 
migratory species. However, incidental gillnet landings of porbeagle 
sharks have occurred in the Gulf of Maine. Gillnet fisheries operating 
in this area are subject to the requirements of other fishery 
management plans such as the Northeast multispecies and monkfish plans. 
These plans restrict the mesh sizes and overall fishing effort in the 
Gulf of Maine. The commercial porbeagle shark fishery is regulated by a 
TAC of 11.3 mt dressed weight (dw) (24,912 lb dw) and a commercial 
quota. The U.S. commercial quota is the portion of the TAC that can be 
landed by fishermen with a commercial fishing permit and is adjusted 
annually based on any overharvest from previous years. In recent years, 
the commercial quota was reduced due to overharvest from previous 
fishing years. The commercial quota was 1.5 mt (3,307 lb) dw in 2010, 
1.6 mt (3,479 lb) dw in 2011, and 0.7 mt (1,585 lb) dw in 2012. In 
2013, the fishery was closed due to overharvest in the previous years. 
It reopened in 2014 with a quota of 1.2 mt (2,820 lb) dw; however, by 
early December 2014, 198 percent of the quota (2.5 mt dw or 5,586 lb 
dw) had been reported landed and triggered a commercial fishery closure 
for the rest of 2014 and all of 2015. This reported overharvest 
represents approximately 27 individual fish if the catch consisted of 
large adults (Curtis et al., 2016). It is unlikely that this 
overharvest represents a significant threat to the species as it 
represents only a small fraction of the estimated abundance (i.e., 27 
fish out of hundreds of thousands). The 2016 commercial quota in the 
U.S. is 1.7 mt dw (3,594 lbs dw). There have been no landings in 2016 
so far. In the past, most of the landings occurred in the fall.
    Landings in Canada have progressively decreased from a peak of 
1,400 mt (3,086,471 lbs) in 1995 to 92 mt (202,825 lbs) in 2007, 
corresponding with decreasing TAC levels. Canadian landings have been 
below the TAC since 2007. There were no landings in the directed 
fishery in 2012, and the directed fishery has been closed since 2013.
    At mortality rates less than four percent of the vulnerable 
biomass, recovery for the Northwest Atlantic stock was estimated to be 
achievable in 5 to 100 years (Campana et al., 2012). Estimated recovery 
times vary based on assumed productivity and harvest rates. The authors 
concluded that all the analyses indicate that the porbeagle shark 
population can recover at modest fishing mortalities but that the time 
horizon for recovery is sensitive to the amount of human-induced 
mortality. They note that the known cause of human-induced mortality is 
bycatch, and it is under management controls (Campana et al., 2012). 
Generally, the vulnerable biomass is that portion of the population 
that is biologically available to the fishery to catch. That is, it is 
of a size that can be caught in the gear used in the fishery; the 
vulnerable biomass is not the amount that they are allowed to catch. 
The gears used in the shark fisheries select for larger fish. In 2009, 
the vulnerable biomass in the Northwest Atlantic assessment was 
estimated to be between 4,406 and 5,092 mt (9,713,568 and 11,228,143 
lbs) (Campana et al., 2012).
    There are restrictions on catch in the EU. In 2010, regulations set 
the EU TAC at zero in domestic waters and prohibited EU vessels from 
fishing for, retaining on board, transferring from one ship to another, 
and landing porbeagle sharks in international waters. Since 2010, the 
TAC has been at zero (SCRS, 2014). Under the older TAC of 436 mt 
(961,200 lbs), the Northeast Atlantic stock was projected to remain 
stable (ICES/ICCAT, 2009). The elimination of directed and bycatch 
fisheries is expected to allow the population to rebuild.
    Data in the Southern Hemisphere are more limited. Since 2000, the 
CPUE in the Uruguayan fleet has been stable or slightly increasing 
(Pons and Domingo, 2010); and Uruguay prohibited retention of porbeagle 
sharks in 2013. Argentinian and Chilean fisheries have also harvested 
porbeagle sharks as incidental catch. In Argentina, catches ranged from 
19-70 mt (41,890-154,300 lbs) from 2003-2006. Live sharks greater than 
4.9 ft (1.5 m) are required to be released (CITES, 2013). In Chilean 
fisheries, landings are mostly unreported but are thought to comprise 
less than two percent of harvests (Hernandez et al., 2008). Semba et 
al., (2013) analyzed distribution and abundance trends in the Southern 
Hemisphere using CPUE data from the southern bluefin tuna longline 
fishery (see above). During this study, they found that the fishery 
occurs primarily on the edge of porbeagle shark habitat and that the 
majority of the shark's distribution is located outside of where the 
fishery operates. The authors also assert that there is only a small 
overlap between porbeagle sharks and the eastern Pacific purse seine 
fisheries. Catches in Australia and New Zealand have also declined 
significantly due to reductions in fishing effort and

[[Page 50475]]

protective regulations. The available data indicate that this stock has 
stabilized (ICES/ICCAT, 2009; Pons and Domingo, 2010; Semba et al., 
2013; Curtis et al., 2016). Bycatch in non-directed fisheries could be 
an ongoing source of fishing mortality (Simpson and Miri, 2013).
    Although catch on the high seas, including the Japanese catch of 
porbeagle sharks outside of the Canadian Exclusive Economic Zone, was 
once considered a significant factor in total catch from the 
Northwestern Atlantic stock of porbeagle sharks, the ICES/ICCAT (2009) 
assessment found that catch levels on the high seas occurred at low 
levels, indicating that bycatch and directed catch in this area is 
minor and does not pose a significant risk to the species (ICES/ICCAT, 
2009). Information on catch ratios indicated that the relative 
abundance of porbeagle shark in the catch tended to be greatest on or 
near the continental shelf and declined markedly in the high seas 
(ICES/ICCAT, 2009). There were differences in the catch ratios among 
fisheries from different nations, but the relative proportion of 
porbeagle sharks in the high seas catch was almost always less than 2 
percent (ICES/ICCAT, 2009). Bycatch of porbeagle sharks within some 
major ICES and Northwest Atlantic Fisheries Organization (NAFO) 
longline fisheries was reported to be very rare, and bycatch in the 
North and South Atlantic swordfish pelagic longline fisheries was very 
low (ICES/ICCAT 2009). Because North Atlantic porbeagle stocks are 
increasing in abundance, any ongoing discards or additional unreported 
mortality does not appear to be of a magnitude that is negatively 
impacting the stocks.
    In addition to bycatch in pelagic longline gear, incidental catch 
in Canada and the United States occurs in trawl, gillnet, and bottom 
longline fisheries for various groundfish species (Simpson and Miri, 
2013; NAFO, unpublished data: www.nafo.int). Using fisheries data and 
observer data, Simpson and Miri (2013) estimated bycatch in Canada's 
Newfoundland/Grand Banks Region (NAFO Division 3LNOP). From 2006-2010, 
bycatch averaged 19 mt (41,890 lb) per year (Simpson and Miri, 2013). 
Total reported landings, which includes directed and incidental catch, 
from NAFO fisheries averaged 43.2 mt (95,240 lb) per year from 2010-
2014 (NAFO unpublished data as cited in Curtis et al., 2016). These 
data are included in assessment and management of the Northwest 
Atlantic stock.
    Underreporting of incidental catch is often noted as a concern 
(ICES/ICCAT, 2009; CITES, 2013; Simpson and Miri, 2013), particularly 
in high seas fisheries. The level of capture of porbeagle sharks in the 
high seas longline fisheries is unclear as there is non-reporting and 
generic reporting of sharks. However, the ICES/ICCAT (2009) assessment 
estimated the potential porbeagle shark catch based on observed catch 
ratios of porbeagle sharks to tuna and swordfish. For the Northwest 
Atlantic, this analysis indicated that unaccounted high seas longline 
catches were a minor portion of the total reported catch historically 
and that catches have been even smaller in recent years (ICES/ICCAT, 
2009). The data on non-reporting in Southern Hemisphere fisheries are 
less certain, but there is little evidence that these catches would 
significantly alter stock assessments (Semba et al., 2013; Francis et 
al., 2014).
    Recreational catch is minimal (NMFS, 2013). Harvests are extremely 
low in the United States, Canada, and New Zealand (CITES, 2009; WCPFC, 
2014). Regulations in Canada and the United States limit the gear that 
is allowed to be used for sharks. Most porbeagle sharks caught in 
recreational fisheries are released with a small percentage being 
retained. In the United States, porbeagle sharks must be at least 4.5 
ft (137 cm) fork length and one shark (porbeagle or other) per vessel 
per trip can be landed. Recreational gears in the United States are 
restricted to rod and reel and handline.
    Estimates of the catch in the United States vary depending on the 
data source analyzed. Data on recreational catch are available through 
the Marine Recreational Fisheries Statistics Survey (MRFSS) and from 
the large pelagic survey (LPS). MRFSS is a generalized angler survey; 
LPS is a specialized survey focused on highly migratory species such as 
pelagic sharks and tunas. This specialization allows for a higher level 
of sampling needed to obtain more precise estimates. However, because 
of limited overlap in species distribution and recreational fishery 
effort, some species such as porbeagle sharks are less commonly 
encountered by recreational anglers (Curtis et al., 2016). During the 
summer when fishing effort is higher, porbeagle sharks are distributed 
farther north and offshore. Due to these lower encounters, even the 
specialized surveys are not able to produce precise estimates of 
overall catch. Data from the LPS survey from 2010 through 2015 indicate 
that 15 porbeagle sharks were observed or reported as kept and 103 were 
observed or reported as released alive; none were observed or reported 
as released dead (NMFS, 2015).
    When animals are captured and released, whether in commercial or 
recreational fisheries, it is important to understand at-vessel and 
post-release mortality. At-vessel mortality rate is the percentage of 
animals that are dead when retrieved from the fishing gear; post-
release mortality refers to the percentage of animals that die after 
being released from fishing gear alive. Several researchers have 
evaluated at-vessel mortality, and mortality rates have varied. In 
several of the studies, at-vessel mortality in longline gear averaged 
around 20 percent (Marshall et al., 2012; Griggs and Baird, 2013; 
Gallagher et al., 2014; NMFS HMS Logbooks), while other studies have 
found higher rates up to approximately 44 percent (Francis et al., 
2004; Coelho et al., 2012; Campana et al., 2015), meaning that of the 
porbeagle sharks caught, 20-44 percent are dead when retrieved from the 
gear. Campana et al., (2015) also evaluated post-release mortality 
rates as determined from PSAT studies. Healthy porbeagle sharks had a 
10 percent post-release mortality rate, while injured porbeagle sharks 
had a 75 percent mortality rate. The overall mortality due to capture 
and discard mortality was then calculated as the sum of the post-
release mortality rates for healthy and injured sharks, weighted by the 
frequency of injury as recorded by fisheries observers from 2010-2014, 
plus the observed frequency of dead sharks. Of porbeagle sharks 
reported by the observers, the mean annual percentage of injured sharks 
at release from pelagic longlines was 14.6 percent. Healthy sharks 
accounted for 41.6 percent. Applying the 75 percent mortality rate to 
the 14.6 percent injury rates and the 10 percent mortality rate to the 
41.6 percent healthy sharks resulted in an overall post-release 
mortality rate of 27.2 percent. Total mortality includes both hooking 
and post-release mortality. In this study of the Canadian pelagic 
longline fishery, the mean at-vessel mortality was 43.8 percent. When 
combined with an overall post release mortality of live (healthy and 
injured sharks), this yielded an overall non-landed fishing mortality 
of 59 percent (Campana et al., 2015).
    Applying the 27 percent mean post-release mortality rate to the 
mean 20 percent mortality rate from the other studies suggests an 
average total mortality of approximately 47 percent. These studies 
suggest that there is great deal of variability in mortality rates. 
Survival rates are dependent on numerous factors, including soak time,

[[Page 50476]]

handling, water temperature, shark size, shark sex, degree of injury, 
etc. (Campana et al., 2015). The studies indicate a moderate to high 
risk of mortality to a porbeagle shark once it is hooked on longline 
gear (Curtis et al., 2016). The elimination of most directed fisheries 
and reductions in catches are likely reducing overall fishing 
mortality. The status review concluded that, while it had been the 
primary threat, overutilization no longer appears to be a threat to the 
species' survival anywhere in its range. The ERA team ranked the threat 
as medium as it is likely that it contributes or will contribute to the 
decline of the species. Continued fishery management efforts are 
necessary to rebuild populations and prevent future declines (Curtis et 
al., 2016).
    The ERA team also considered whether any of the demographic factors 
or other threats would interact with this threat to increase its 
overall threat level. As described above, stocks have been overfished; 
however, fishing pressure has decreased, and overfishing is no longer 
occurring. Stocks have stabilized, and some are increasing. Under 
current management, stocks are projected to continue to recover. 
Therefore, this threat was ranked as medium. The threat from 
overutilization would be higher if there were threats due to inadequate 
regulation coupled with the life history of porbeagle sharks (low 
productivity). As described below, the inadequacy of existing 
regulations measures was determined to be a low risk by the ERA team 
for the North Atlantic DPS and medium for the Southern Hemisphere DPS. 
Regulatory mechanisms to protect porbeagle sharks are widespread and 
improving throughout their range. The porbeagle shark's inherently low 
productivity indicates that recovery from overutilization will take a 
long time, on the order of decades. After considering these factors, 
the ERA team concluded that the threat from overutilization would not 
significantly increase due to interactions with other risk factors. 
Therefore, the ERA team maintained the ranking of medium.
    The only interactions with overutilization identified by the status 
review team were the inadequacy of regulatory mechanisms and the 
porbeagle shark's growth rate/productivity. However, we also evaluated 
potential interactions between overutilization and spatial structure/
connectivity and overutilization and diversity. Risks associated with 
spatial structure/connectivity and diversity are both ranked very low 
for the North Atlantic and Southern Hemisphere DPSs. Porbeagle sharks 
are distributed broadly across both the North Atlantic and the Southern 
Hemisphere. The species is highly mobile, and, as described above, the 
available data indicate that there is connectivity within each DPS. The 
genetic studies also indicate that there is high genetic diversity and 
reproductive connectivity within each DPS. Genetic diversity appears to 
be sufficiently high and not indicative of isolated or depleted 
populations. Overutilization does not appear to have reduced the 
genetic diversity or limited the spatial distribution and connectivity. 
Given this and that the risk from both these factors is considered very 
low, interactions between these factors and overutilization would not 
increase the ranking from medium.
    Disease and Predation: Disease and predation were ranked as very 
low risk for both DPSs. Porbeagle sharks are an apex predator residing 
at the top of the food web. Rarely, white sharks and orcas will prey on 
porbeagle sharks. However, predation on the species is very low. In 
general, sharks may be susceptible to diseases, but there is no 
evidence that disease has ever caused declines in shark populations 
(Curtis et al., 2016). Sharks have shown occurrences of cancer, but 
rates are unknown (National Geographic, 2003). There is no evidence 
that either of these threats is negatively impacting either DPS.
    Inadequacy of Existing Regulatory Mechanisms: This threat was 
ranked as low for the North Atlantic DPS and as medium for the Southern 
Hemisphere DPS. Porbeagle sharks are managed by Fisheries and Oceans 
Canada (DFO), NMFS, and the EU. Australia, New Zealand, Argentina, and 
Uruguay also manage porbeagle sharks in their waters. Several 
international organizations, including the North East Atlantic 
Fisheries Commission (NEAFC), NAFO, WCPFC, CCAMLR, and ICCAT, also work 
collaboratively on the science and management of this species. 
Porbeagle sharks are listed under several international conventions, 
including the UN Convention on the Law of the Sea (UNCLOS), the 
Barcelona Convention Protocol, the Bern Convention on the Conservation 
of European Wildlife and Habitats, the Convention for the Protection of 
the Marine Environment of the North-east Atlantic (OSPAR), the Bonn 
Convention on the Conservation of Migratory Species (CMS), and CITES.
    Porbeagle sharks are listed under Annex I of UNCLOS which 
establishes conservation for highly migratory fish stocks on the high 
seas and encourages cooperation between nations on their management. 
Listings under Annex II of the Barcelona Convention, Appendix III of 
the Bern Convention, and Annex V of the OSPAR Convention are intended 
to protect porbeagle sharks and their habitats in the Northeast 
Atlantic and the Mediterranean Sea. The CMS Migratory Shark Memorandum 
of Understanding and Appendix II of CMS aim to enhance conservation of 
migratory sharks and require range states to coordinate management 
efforts for trans-boundary stocks. Inclusion under Appendix II of CITES 
results in regulation of trade and close monitoring. International 
trade must be non-detrimental to the survival of the stock. CCAMLR 
implemented a moratorium on all directed shark fishing in the Antarctic 
region in 2006 and encourages the live release of incidentally caught 
sharks. Under these governments, organizations and conventions, 
porbeagle sharks are currently one of the most widely protected sharks 
in the world.
    Management efforts and regulations that benefit porbeagle sharks 
have increased in the United States, Canada, and other waters in recent 
years. In the United States, the shark must be landed with its fins 
naturally attached (which helps prevent the illegal practice of 
finning, as species identification is enhanced by the presence of fins 
which may facilitate identification for enforcement and data 
collection), a commercial fishing permit is required, and the fishery 
is regulated by a TAC that is adjusted annually based on any 
overharvests. Other measures in highly migratory species fisheries in 
the United States include retention limits, time/area closures, 
observer requirements, and reporting requirements. These measures are 
designed to prevent overfishing and allow an increase in biomass. 
Canada has closed the mating grounds to directed fisheries, and catch 
is regulated by a TAC limit that has been lowered in recent years. In 
2013, Canada suspended the directed porbeagle shark fishery and will 
not resume it until the stock has sufficiently recovered (Canada/ICCAT 
2014, Doc. No. PA4-810). Canada also has a national plan for the 
conservation and management of sharks and their long-term sustainable 
use. This plan outlines monitoring and management measures, including 
observer coverage and dockside monitoring. New Zealand and Australia 
have harvest quotas, and catches have been greatly reduced. Uruguay has 
also implemented fishing regulations for porbeagle sharks.
    An ICCAT working paper from the 19th Special Meeting of ICCAT (CPC/
ICCAT, 2015; Doc. No. COC 314/2014)

[[Page 50477]]

summarizes how ICCAT members are implementing shark measures. Belize 
reported that they do not conduct scientific research for porbeagle 
sharks or catch them in the convention area; Japan reports that no tuna 
longline vessels are targeting porbeagle sharks and incidental catch is 
retained with all parts or released alive. The United Kingdom indicated 
that porbeagle sharks are rarely caught. Porbeagle sharks are a 
prohibited species in the EU and Turkey; there is no permitted harvest 
in these countries. Retention of porbeagle sharks has been prohibited 
in Uruguay since 2013. In 2015, ICCAT adopted additional measures that 
require all vessels promptly release unharmed porbeagle sharks when 
brought alive alongside the vessel and improved reporting, and 
encouraged research and monitoring to improve assessments. Similarly, 
NEAFC prohibited all directed fishing for porbeagle in the NEAFC area 
(high seas) by vessels flying their flag. Incidentally caught porbeagle 
sharks must be promptly released unharmed.
    Domestic, regional, and international regulation designed to reduce 
catch and rebuild stocks have been broadly implemented. Directed 
porbeagle shark fisheries have been mostly eliminated, many fisheries 
require live release of incidentally caught animals, and trade 
restrictions have been implemented. This improved management has 
resulted in declining catches, and overfishing is not occurring. The 
ERA team ranked this factor as low for the North Atlantic population 
and as medium for the Southern Hemisphere, where there is less rigorous 
monitoring, reporting and enforcement of regulations resulting in more 
uncertainty in their effectiveness.
    In both DPSs, this threat could interact with the medium threat of 
overutilization to increase the risk of extinction and with the 
demographic factor of slow population growth rates to increase the risk 
of extinction. The threat of overutilization has been reduced through 
improved management as has this threat. The shark's inherently low 
productivity means that recovery from past utilization will take 
decades, but this would not significantly increase the ranking of this 
threat as the current regulations have ended overfishing and stocks are 
rebuilding. The ERA team found that the significant interacting threats 
are being simultaneously reduced, supporting the low and medium 
rankings for the North Atlantic and Southern Hemisphere DPSs, 
respectively.
    We also considered whether measures to protect the species (e.g., 
closed areas, fishery restrictions, etc.) had been implemented 
effectively. With respect to the conservation measures described here, 
the measures have been implemented. Despite some uncertainties around 
the monitoring and enforcement of the measures in the Southern 
Hemisphere, both DPSs have stabilized and, in some areas are 
increasing. Therefore, regulations to reduce the threat of 
overutilization appear to be effective and are positively affecting the 
status of the porbeagle sharks in both DPSs.

Other Natural or Manmade Factors Affecting the Porbeagle's Continued 
Existence

    Overall, this threat was ranked low for both DPSs. Genetic studies 
indicate that isolation is not a factor affecting this species in the 
North Atlantic. In the Southern Hemisphere, the population is 
widespread in a continuous circumglobal band, and there is no evidence 
that any of the populations in the Southern Hemisphere might be 
isolated. Given its migratory nature, isolation does not appear to be a 
factor impacting the porbeagle shark.
    Low productivity has the potential to make the species more 
vulnerable to threats, but is considered in modelling and assessment 
and in management and conservation actions. Several Ecological Risk 
Assessments have evaluated the productivity of the porbeagle shark in 
terms of its vulnerability to certain fisheries. Results from these 
assessments have varied. Cortes et al., (2010) and Murua et al., (2012) 
found porbeagle sharks less vulnerable than other shark species to 
pelagic longline fisheries in the Atlantic and Indian Oceans, 
respectively. Cortes et al., (2010) conducted a quantitative assessment 
that consisted of a risk analysis to evaluate the productivity of the 
stocks and a susceptibility analysis to assess their propensity to 
capture and mortality in pelagic longline fisheries. In this 
assessment, vulnerability considered both productivity and 
susceptibility to evaluate relative risk. They found that porbeagle 
sharks were less vulnerable than other shark species to pelagic 
longlines in the Atlantic Ocean (Cortes et al., 2010). Murua et al., 
(2012) also ranked the vulnerability of porbeagle sharks based on the 
productivity and susceptibility to fishing gear. In the Indian Ocean, 
porbeagle ranked eight (rankings 1-16 with lower numbers being more 
vulnerable (Murua et al., 2012)). SCRS (2014) reported on a risk 
assessment carried out for 20 stocks of pelagic sharks, finding 
porbeagle sharks to rank fourth in vulnerability (1 being most 
vulnerable) to pelagic longline gear. The Ecological Risk Assessment 
conducted by the committee was a quantitative assessment consisting of 
a risk analysis to evaluate productivity and susceptibility of stocks 
in the Atlantic to being caught in pelagic longline gear (SCRS, 2014; 
Cortes et al., 2015).
    The results of an ecological risk assessment are used to determine 
a species' vulnerability to a specific fishery and can be a first step 
in the assessment process. Although a risk assessment considering a 
specific vulnerability may rank porbeagle sharks higher than other 
sharks in some respects, this is not necessarily an indicator of a high 
risk of extinction. Thus, results of stock assessments, which 
incorporate additional and more quantitative sources of information 
than ERAs, should generally outweigh the qualitative outputs from ERAs 
when available.
    Global climate change, including warming and acidification, is 
unlikely to substantially impact porbeagle populations. The species has 
an inherently high adaptive capacity. They are highly mobile, have a 
broad temperature tolerance, and have a generalist diet. They are 
highly likely to adapt to changing conditions. Chin et al., (2010) 
found that continental shelf- and pelagic sharks have a low overall 
vulnerability to climate change.
    In an assessment of 82 Northeast U.S. fishery species, Hare et al., 
(2016) found that porbeagle sharks have, on a scale of low to very 
high, a high vulnerability to climate change. Exposure to warming ocean 
temperatures and ocean acidification was considered high for most 
species in this region (Hare et al., 2016). This high sensitivity was 
influenced by the porbeagle shark's low productivity and overfished 
status. Most other sensitivity attributes, including habitat and prey 
specificity, mobility, early life history requirements, were considered 
to be low for porbeagle sharks (Hare et al., 2016). Therefore, we 
expect the overall vulnerability to drop as populations rebuild. Hare 
et al., (2016) indicated that the overall climate vulnerability ranking 
would drop to moderate if the poor stock status is removed as a factor. 
In addition, the mobility and temperature tolerances of the species are 
expected to limit the impacts from climate change. The distribution of 
porbeagle sharks may shift away from the northeast United States with 
climate change; its overall population is likely to persist (Curtis et 
al., 2016). Due to their high mobility and temperature tolerances, the 
overall directional effect of climate changes was

[[Page 50478]]

considered to be neutral (Hare et al., 2016).
    This threat may interact with the threat of overutilization and the 
demographic factor of low population growth rates. Since 
overutilization is being reduced through improved management, which 
takes into account the porbeagle shark's life history (e.g., 
restricting directed fishing in mating areas), this threat is expected 
to remain as low for both DPSs.

Summary of Demographic Factors and Threats Affecting Porbeagle Sharks

    Both demographic factors and threats were ranked on a scale from 
very low to very high by the ERA team members. For the demographic 
factors, diversity and spatial structure/connectivity were ranked very 
low for each DPS, abundance was ranked low for each DPS, and growth 
rate/productivity was ranked medium for each DPS. For the threats, 
habitat destruction, modification, or curtailment and disease or 
predation were both ranked very low for each DPS; inadequacy of 
existing regulation mechanisms was ranked low for the North Atlantic 
DPS and other natural or manmade threats was ranked low for each DPS; 
overutilization was ranked medium for each DPS and inadequacy of 
existing regulation mechanisms was ranked medium for the Southern 
Hemisphere DPS. No demographic factors or threats were ranked high or 
very high.
    The only demographic factor ranked above low was growth rate/
productivity. The porbeagle shark's life history traits make the 
populations vulnerable to threats and slow to recover from depletion. 
The only threats ranked above low are overutilization (both DPSs) and 
inadequacy of existing regulatory mechanisms (Southern Hemisphere DPS). 
These threats are ranked as medium. Recent management efforts across 
the globe have reduced fishing mortality. There are a number of 
countries or organizations that restrict the harvest of porbeagle 
sharks. Due to these efforts, stocks are no longer declining and most 
have begun to recover. Given their life history traits, recovery is 
likely to take decades, but demographic risks are mostly low and 
significant threats have been reduced. The inadequacy of existing 
regulatory mechanisms for the Southern Hemisphere DPS was ranked medium 
due to uncertainties in monitoring, reporting, and enforcement of 
regulations when compared to the North Atlantic, suggesting the 
Southern Hemisphere DPS may be more vulnerable to this threat.

Overall Risk Summary

    As described, the ERA team used a ``likelihood analysis'' to 
evaluate the overall risk of extinction. The ERA team did not find 
either DPS to be at high risk of extinction as no team members assigned 
points to this category. For the North Atlantic DPS, the current level 
of extinction risk was 7.5 percent likelihood of moderate risk, 80 
percent likelihood of low risk, and 12.5 percent likelihood of not at 
risk. For the foreseeable future, the ERA team found that the level of 
moderate risk remained the same, the level of low risk decreased to 
62.5 percent and the not-at-risk level increased to 30 percent. For the 
Southern Hemisphere population, the current levels were 25 percent 
likelihood of moderate risk, 72.5 percent likelihood of low risk, and 
2.5 percent likelihood of not at risk. Similar to the North Atlantic 
DPS, the level of moderate risk for the Southern Hemisphere DPS 
remained at 25 percent in the foreseeable future; the low risk 
decreased to 70 percent, and the not at risk category increased to 5 
percent.
    While these numbers reflect the percentage of risk assigned to each 
category, we also evaluated the points assigned to each category by 
individual team members to better understand the risk. Each individual 
team member assigned 10 points across the risk categories. As described 
above, no points were assigned to the high risk category for the North 
Atlantic DPS for the current or foreseeable future categories of risk. 
In the North Atlantic DPS, no more than 1 point was assigned by any 
individual to the moderate risk currently or in the foreseeable future. 
Each team member assigned eight points to the low risk category and one 
or two points to the not at risk category for the current risk. For the 
foreseeable future, team members assigned 4 to 8 points to the `low 
risk' and 1 to 6 to the `not at risk' categories.
    As with the North Atlantic DPS, each team member assigned 10 points 
across the four categories for the Southern Hemisphere DPS. No team 
member assigned points to the high risk category for this DPS for 
either the current or foreseeable future level of risk. For the current 
level of extinction risk, team members each assigned 2-3 points to the 
moderate category and 7-8 points to the low category; one team member 
assigned a single point to the not at risk category. For the level of 
risk through the foreseeable future, team members assigned 1-4 points 
to the moderate category and 6-8 points to the low category; two team 
members each assigned one point to the not at risk category.
    The ERA team determined that, overall, both DPSs are at low risk of 
extinction. While the overall risk is low, there is some likelihood of 
a moderate risk of extinction, especially in the Southern Hemisphere 
DPS. The scoring, along with the information in the status review, 
indicates that the moderate level of risk in the Southern Hemisphere 
population is due to the uncertainty in current stock status and 
projections for the Southern Hemisphere, and more uncertainty about the 
adequacy of current and future regulatory mechanisms, including fishery 
monitoring, reporting, and enforcement in that region. In addition, 
generation times are longer in the Southern Hemisphere and the DPS is 
potentially more vulnerable to depletion. Populations with longer 
generation times and low productivity cannot rebound as quickly as 
populations with short generation times and high productivity. 
Considering the factors and despite the uncertainty, each team member 
assigned the majority of the points to the low risk category, resulting 
in 75 percent of the points being assigned to the low/not at risk 
categories. Based on this, we conclude that, while there is some 
uncertainty, the Southern Hemisphere DPS is at low risk of extinction 
currently and in the foreseeable future. We also conclude that the 
North Atlantic DPS is at low risk of extinction currently and in the 
foreseeable future.
    The ERA team noted that there is a higher likelihood that the North 
Atlantic DPS is at low risk of extinction than the Southern Hemisphere 
DPS. Despite these concerns, they still agreed that there was a much 
greater likelihood of Southern Hemisphere porbeagle sharks having an 
overall low risk of extinction. For both DPSs, the ERA team determined 
that overall extinction risk is likely to be lower in the foreseeable 
future (40 years) than it is currently, due to improved management and 
recent indications of population recoveries. This decrease in risk in 
the foreseeable future is reflected in the decrease in the percentages 
in the low level category and the increases in the not at risk 
category. This shift, while relatively small in the Southern 
Hemisphere, indicates that the porbeagle population will face fewer 
threats and populations will grow, provided effective management 
continues to be implemented. Recovery is likely to take decades, but 
the demographic risks are mostly low, and significant threats have been 
reduced.

[[Page 50479]]

    We have independently reviewed the best available scientific and 
commercial information, including the status review report (Curtis et 
al., 2016) and other published and unpublished information. We 
concluded that the two DPSs are not in danger of extinction or likely 
to become so in the foreseeable future throughout their ranges. As 
described earlier, an endangered species is ``any species which is in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species is one ``which is likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The ERA team ranked the demographic 
criteria and the five factors identified in the ESA and completed an 
assessment of overall risk of extinction. The ERA team provided this 
information to us to determine whether listing is warranted. We 
reviewed the results of the ERA and concurred with the team's 
conclusions regarding extinction risk. We then applied the statutory 
definitions of ``threatened species'' and ``endangered species'' to 
determine if listing either of the DPSs based on the ERA results and 
other available information is warranted.
    The ERA team concluded that the level of extinction risk to the 
North Atlantic DPS is low, with 92.5 percent of its likelihood points 
allocated to the ``low risk'' or ``not at risk'' category, both now and 
in the foreseeable future. Furthermore, the percentage assigned to the 
``not at risk'' category increased for the foreseeable future, while 
the percentage assigned to the ``low risk'' category decreased. The ERA 
team allocated only 7.5 percent of its likelihood points to the 
``moderate extinction risk'' category, both now and in the foreseeable 
future. Given this low level of risk and an evaluation of the 
demographic parameters and threats, we have determined that this DPS 
does not meet the definition of an endangered or threatened species 
and, as such, listing under the ESA is not warranted at this time.
    The ERA team concluded that the Southern Hemisphere DPS was at low 
risk of extinction, though their distribution of likelihood points 
indicates that there was some uncertainty about this. However, 75 
percent of the likelihood points were allocated to the ``low risk'' or 
``not at risk of extinction'' category. The ERA Team's uncertainty 
about the level of risk is due to some uncertainty in the stock status, 
projections, and fishery monitoring/enforcement. Described in detail 
elsewhere, the primary threat to porbeagle sharks is overfishing. 
Strict management measures have been implemented to minimize this 
threat and, given that abundance and biomass have stabilized, these 
measures appear to be effective in addressing the threat. In addition, 
the available information indicates that the current population, while 
reduced from known historical levels, is sufficient to maintain 
population viability. We agree with the ERA Team's conclusions, and, 
therefore, we conclude that this DPS does not warrant listing as 
threatened or endangered under the ESA at this time.
    We also considered the risk of extinction of porbeagle sharks 
throughout their range. As described above, porbeagle sharks are found 
in both the Northern and Southern Hemispheres. There is no evidence 
that this range has contracted or that there has been any loss of 
habitat. The abundance and biomass have stabilized and in many areas 
are increasing. As indicated above, overfishing is the primary threat 
to the species throughout its range. Regulations, both domestic and 
international, have been put in place across the range and overfishing 
is not occurring. As the primary threat has been reduced, the 
population has stabilized, and neither of the DPSs are threatened or 
endangered, we have concluded that the species as a whole is not 
threatened or endangered.

Significant Portion of Its Range

    Though we find that the porbeagle shark, the North Atlantic DPS of 
the porbeagle shark, and the Southern Hemisphere DPS of the porbeagle 
shark (all of which are considered ``species'' under the ESA) are not 
in danger of extinction now or in the foreseeable future, under the SPR 
Policy, we must go on to evaluate whether these species are in danger 
of extinction, or likely to become so in the foreseeable future, in a 
``significant portion of its range'' (79 FR 37578; July 1, 2014).
    When we conduct an SPR analysis, we first identify any portions of 
the range that warrant further consideration. The range of a species 
can theoretically be divided into portions in an infinite number of 
ways. However, there is no purpose to analyzing portions of the range 
that are not reasonably likely to be significant or in which a species 
may not be endangered or threatened. To identify only those portions 
that warrant further consideration, we determine whether there is 
substantial information indicating that (1) the portions may be 
significant and (2) the species may be in danger of extinction in those 
portions or likely to become so within the foreseeable future. We 
emphasize that answering these questions in the affirmative is not a 
determination that the species is endangered or threatened throughout a 
significant portion of its range--rather, it is a step in determining 
whether a more detailed analysis of the issue is required (79 FR 37578, 
July 1, 2014). Making this preliminary determination triggers a need 
for further review, but does not prejudge whether the portion actually 
meets these standards such that the species should be listed.
    If this preliminary determination identifies a particular portion 
or portions for potential listing, those portions are then fully 
evaluated under the ``significant portion of its range'' authority as 
to whether the portion is both biologically significant and endangered 
or threatened. In making a determination of significance, we consider 
the contribution of the individuals in that portion to the viability of 
the species. That is, we determine whether the portion's contribution 
to the viability is so important that, without the members in that 
portion, the species would be in danger of extinction or likely to 
become so in the foreseeable future.
    The SPR policy further explains that, depending on the particular 
facts of each situation, NMFS may find it is more efficient to address 
the significance issue first, but in other cases it will make more 
sense to examine the status of the species in the potentially 
significant portions first. Whichever question is asked first, an 
affirmative answer is required to proceed to the second question. Id. 
``[I]f we determine that a portion of the range is not `significant,' 
we will not need to determine whether the species is endangered or 
threatened there; if we determine that the species is not endangered or 
threatened in a portion of its range, we will not need to determine if 
that portion is `significant''' (79 FR 37587). Thus, if the answer to 
the first question is negative--whether it addresses the significance 
question or the status question--then the analysis concludes, and 
listing is not warranted.
    As described elsewhere, the ERA team determined that there are two 
DPSs of porbeagle shark. Therefore, we will apply the SPR policy to the 
North Atlantic DPS, the Southern Hemisphere DPS, and the taxonomic 
species separately. The first step in applying the SPR policy is to 
identify portions of the range that may be significant and in which the 
species may be threatened or endangered.
    In the North Atlantic DPS, we preliminarily identified two portions 
for further consideration--the western North Atlantic and the 
Mediterranean

[[Page 50480]]

Sea. Porbeagle sharks in the western North Atlantic may be more 
susceptible to threats than those in the eastern North Atlantic given 
that the western area includes known and suggested locations for mating 
and pupping (birthing). In addition, Campana et al. (2015b) identify 
Emerald Basin off Nova Scotia, Canada, as a potential sensitive life 
history area at least in the fall. Emerald Basin is an area with high 
densities of juveniles (Campana et al., 2015b). The available research 
indicates that mating occurs in at least two locations. The first 
mating ground identified is on the Grand Banks, off southern 
Newfoundland and at the entrance to the Gulf of St. Lawrence. A second 
mating ground was identified on Georges Bank, based on high catch rates 
and similar aggregations of mature females that did not appear to be 
feeding (Campana et al., 2010b). Research also suggests that there may 
be a pupping ground in the Sargasso Sea (Campana et al., 2010a). 
Transmissions were received from 21 PSATs applied in the summer to 
porbeagle sharks off the eastern coast of Canada between 2001 and 2008. 
While males and immature sharks remained in the cool temperate water, 
all tagged mature females exited these waters by December, swimming to 
the Sargasso Sea. Pupping was strongly suggested based on the 
observation that only the sexually mature females made the migration 
and the residency in the Sargasso Sea overlapped with the known pupping 
period (Campana et al., 2010a). However, pupping was not directly 
observed, only logically inferred from the tagging data. Both the 
mating and pupping stages of the life history can concentrate the 
species in specific areas making them more vulnerable to threats in 
those areas.
    In order to determine whether the western North Atlantic 
constitutes a significant portion of the North Atlantic DPS' range, we 
first examined whether this portion of the range is biologically 
significant. A portion of the range of a species is ``significant'' if 
the portion's contribution to the viability of the species is so 
important that, without the members of that portion, the species would 
be in danger of extinction, or likely to become so in the foreseeable 
future, throughout all of its range. As described above, this portion 
of the porbeagle range includes known mating and presumed pupping 
areas. These areas are important to the continued existence of the 
North Atlantic DPS as they allow for recruitment into the population. 
Recruitment into the population must occur for it to increase. While 
similar mating areas likely exist in the Northeast Atlantic, these 
areas have not yet been described. In addition, the loss of porbeagle 
sharks in the western North Atlantic would result in a significant gap 
in the distribution of the North Atlantic DPS as this is a relatively 
large area relative to the spatial distribution throughout the North 
Atlantic. We have concluded that the western North Atlantic portion is 
a significant portion of the North Atlantic DPS under the SPR policy.
    Next, we examined whether porbeagle sharks were endangered or 
threatened in the western North Atlantic portion. As described 
elsewhere, the primary threat to porbeagle sharks is fishing. In the 
mating areas, there is no directed fishery for porbeagle sharks. 
Similarly, there is no directed fishing in the area of Emerald Basin. 
Porbeagle sharks may be incidentally caught in other fisheries. In the 
Sargasso Sea (presumed to be a pupping area), tagged sharks undertook 
multiple ascents and descents between 50 and 850 m (164 and 2,789 ft) 
in waters between 8 and 23 [deg]C (46 and 73[emsp14][deg]F). The mean 
daily depth in April and May was 480 m (1,575 ft) indicating that most 
of the pupping period was spent at depth (Campana et al., 2010), which 
would limit the interactions with anthropogenic threats. While 
individual porbeagle sharks may be caught as bycatch in fisheries on 
the mating grounds or in fisheries in the Sargasso Sea, the population 
in the Northwest Atlantic is increasing (see abundance and trends 
above). If fisheries in these areas were impacting the species to the 
extent that they are threatened or endangered, we would not expect the 
population to continue to grow. That is, impacting essential life 
history needs such as mating or pupping would result in less 
recruitment to the population, which would be reflected in the overall 
population trend. Accordingly, the primary threat in these areas is 
being addressed by existing regulatory measures, precluding directed 
fisheries in the areas. There are no other known significant threats in 
these areas. Based on an evaluation of threats in the areas, the 
population data, and life history of the species, we have determined 
that porbeagle sharks in the western North Atlantic are not threatened 
or endangered.
    The second portion of the North Atlantic DPS' range identified as 
potentially significant under the SPR Policy is the Mediterranean Sea. 
Porbeagle shark abundance in the Mediterranean Sea is low, making them 
more vulnerable to threats in this area. As described elsewhere, the 
main threat to the species in the North Atlantic is fishing. In the 
Mediterranean Sea, catch rates are low. However, the available data 
suggest that porbeagle sharks were historically uncommon in this area. 
In addition, the Mediterranean Sea represents a small portion of the 
range of the North Atlantic DPS, which is found in the Mediterranean 
Sea and the North Atlantic. Given that porbeagle sharks are widely 
distributed and highly mobile within the North Atlantic, we did not 
find that the loss of the Mediterranean Sea portion of the range would 
severely fragment and isolate the population to a point where 
individuals would be prevented from moving to suitable habitats or 
would have an increased vulnerability to threats. We also did not find 
that the loss of this portion would result in a level of abundance for 
the remaining North Atlantic population that would to be so low or 
variable that it would cause the DPS to be at an increased risk of 
extinction due to environmental variation, anthropogenic perturbations, 
or depensatory processes. With mixing between the Northeast Atlantic 
and Mediterranean Sea animals, we would also expect that increases in 
the population in the Northeast Atlantic would have positive impacts on 
the population in the Mediterranean Sea as individuals may move from 
the Northeast Atlantic to the Mediterranean Sea. There is no 
substantial evidence that the loss of the Mediterranean portion of its 
range would isolate the North Atlantic DPS such that the remaining 
populations would be at risk of extinction from demographic processes. 
As described elsewhere, genetic data show that there is mixing between 
the populations across the North Atlantic. If this portion were lost, 
we would not expect it to result in a loss of genetic diversity in the 
DPS as a whole. Overall, we did not find any evidence to suggest that 
this portion of the range has increased importance over any other with 
respect to the species' survival. Given that porbeagle abundance is 
historically low in the Mediterranean Sea, that the Mediterranean Sea 
represents a small portion of the North Atlantic DPS' range, that 
mixing occurs between the Mediterranean Sea and the Northeast Atlantic, 
and that there is no evidence to suggest that the loss of the 
Mediterranean Sea portion would result in the remainder of the North 
Atlantic DPS being endangered or threatened, we have determined that 
this area does not represent a significant part of the North Atlantic 
DPS' range. Given that the portion is not significant, the question of 
whether it is endangered or threatened in this area is not addressed.

[[Page 50481]]

    The other DPS considered under the SPR policy is the Southern 
Hemisphere DPS. Porbeagle sharks in the Southern Hemisphere are found 
in a continuous band around the globe, and the genetic data indicate 
that this population is mixing. For management purposes, ICCAT has 
identified two stocks in the South Atlantic. There may also be an Indo-
Pacific stock. However, stock boundaries in the Southern Hemisphere 
remain unclear (Curtis et al., 2016). As with the North Atlantic DPS, 
the greatest threat to porbeagle sharks in the Southern Hemisphere is 
fishing. Threats from fishing are likely more concentrated closer to 
the coast. However, there is no evidence that porbeagle sharks face a 
higher risk of extinction in one area of the Southern Hemisphere over 
any other. Under the SPR policy, we could not identify, in the 
preliminary analysis, any portion of the porbeagle shark's range in the 
Southern Hemisphere DPS that may be significant and in which members of 
the species may be endangered or threatened. As we did not find 
evidence to suggest that any one portion of the range has increased 
importance over any other with respect to that species' survival, no 
further analysis under the SPR policy was conducted.
    Finally, we also considered whether there is any portion of the 
range of the taxonomic species that could be considered significant 
under the SPR Policy and that is threatened or endangered. Two portions 
of the range of the species could be considered significant: The North 
Atlantic DPS and the Southern Hemisphere DPS. However, as we described 
above in our extinction risk analysis, these two DPSs are not in danger 
of extinction throughout their ranges or likely to become so in the 
foreseeable future. Therefore, there is no need to consider further 
whether any of these two DPSs constitute significant portions of the 
species' range.

Final Determination

    Section 4(b)(1) of the ESA requires that listing determinations be 
based solely on the best scientific and commercial data available after 
conducting a review of the status of the species and taking into 
account those efforts, if any, being made by any state or foreign 
nation, or political subdivisions thereof, to protect and conserve the 
species. We have independently reviewed the best available scientific 
and commercial information, including the petition, public comments 
submitted in response to the 90-day finding (80 FR 16356; March 27, 
2015), the status review report (Curtis et al., 2016), and other 
published and unpublished information, and we have consulted with 
species experts and individuals familiar with porbeagle sharks. We 
identified two DPSs of the porbeagle shark: The North Atlantic DPS and 
the Southern Hemisphere DPS. We considered each of the Section 4(a)(1) 
factors to determine whether it contributed significantly to the 
extinction risk of each DPS on its own. We also considered the 
combination of those factors to determine whether they collectively 
contributed significantly to the extinction risk of the DPSs. As 
previously explained, we could not identify any portion of either DPS' 
range that met both criteria of the SPR policy. Therefore, our 
determination set forth below is based on a synthesis and integration 
of the foregoing information, factors and considerations, and their 
effects on the status of the species throughout each DPS.
    We conclude that neither the North Atlantic nor Southern Hemisphere 
DPS of porbeagle shark is presently in danger of extinction, nor is it 
likely to become so in the foreseeable future throughout all or a 
significant portion of its range. We summarize the factors supporting 
this conclusion as follows: (1) The species is broadly distributed over 
a large geographic range within each hemisphere, with no barrier to 
dispersal within each DPS; (2) genetic data indicate that, within each 
DPS, populations are not isolated, have high genetic diversity, and 
reproductive connectivity; (3) there is no evidence of a range 
contraction, and there is no evidence of habitat loss or destruction; 
(4) while the species possesses life history characteristics that 
increase its vulnerability to overutilization, overfishing is not 
currently occurring within the range of either the North Atlantic or 
Southern Hemisphere DPS; (5) the best available information indicates 
that abundance and biomass has stabilized in the Southern Hemisphere 
and is increasing in the North Atlantic; (6) while the current 
population size in both DPSs has declined from historical numbers, the 
population sizes are sufficient to maintain population viability into 
the foreseeable future and consist of at least hundreds of thousands of 
individuals; (7) the main threat to the species is fishery-related 
mortality from incidental catch; however, there are strict management 
requirements in place to minimize this threat in many areas of the 
North Atlantic and Southern Hemisphere, and these measures appear to be 
effective in addressing this threat; (8) porbeagle shark's high 
mobility, broad temperature tolerance, and generalist habitat and 
opportunistic diet limit potential impacts from climate change; (9) 
directional effects of climate change are expected to be neutral; (10) 
there is no evidence that disease or predation is contributing to 
increasing the risk of extinction of either DPS; and (11) there is no 
evidence that either DPS is currently suffering from depensatory 
processes (such as reduced likelihood of finding a mate or mate choice 
or diminished fertilization and recruitment success) or is at risk of 
extinction due to environmental variation or anthropogenic 
perturbations.
    Based on these findings, we conclude that the North Atlantic and 
Southern Hemisphere DPSs of the porbeagle shark are not currently in 
danger of extinction throughout all or a significant portion of their 
ranges, nor are they likely to become so within the foreseeable future. 
We have further concluded that the species as a whole is not currently 
in danger of extinction throughout all or a significant portion of its 
range nor is it likely to become so in the foreseeable future. 
Accordingly, the porbeagle shark does not meet the definition of a 
threatened or endangered species and, thus, does not warrant listing as 
threatened or endangered at this time.
    Porbeagle sharks from Newfoundland, Canada to Massachusetts, and 
seasonally to New Jersey, were identified as a NMFS ``species of 
concern'' in 2006. A species of concern is one for which we have 
concerns regarding status and threats but for which insufficient 
information is available to indicate a need to list the species under 
the ESA. In identifying species of concern, we consider demographic and 
genetic diversity concerns; abundance and productivity; distribution; 
life history characteristics and threats to the species. Given the 
information presented in the status review and the findings of this 
listing determination, we are removing the designation of species of 
concern for porbeagle sharks in the North Atlantic DPS. This is a final 
action, and, therefore, we do not solicit comments on it.

Classification

National Environmental Policy Act

    The 1982 amendments to the ESA, in section 4(b)(1)(A), restrict the 
information that may be considered when assessing species for listing. 
Based on this limitation of criteria for a listing decision and the 
opinion in Pacific Legal Foundation v. Andrus, 675 F. 2d 825 (6th Cir. 
1981), we have concluded

[[Page 50482]]

that ESA listing actions are not subject to the environmental 
assessment requirements of the National Environmental Policy Act (See 
NOAA Administrative Order 216-6).

References

    A complete list of all references cited herein is available upon 
request (see FOR FURTHER INFORMATION CONTACT).

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: July 25, 2016.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.
[FR Doc. 2016-18101 Filed 7-29-16; 8:45 am]
 BILLING CODE 3510-22-P