Endangered and Threatened Wildlife; Determination on Whether To List the Ribbon Seal as a Threatened or Endangered Species, 41371-41384 [2013-16601]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 78, Number 132 (Wednesday, July 10, 2013)]
[Notices]
[Pages 41371-41384]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-16601]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[Docket No. 1206013117-3579-02]
RIN 0648-XA768


Endangered and Threatened Wildlife; Determination on Whether To 
List the Ribbon Seal as a Threatened or Endangered Species

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

ACTION: Notice of a listing determination and availability of a status 
review document.

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SUMMARY: We, NMFS, have completed a comprehensive status review of the 
ribbon seal (Histriophoca fasciata) under the Endangered Species Act 
(ESA). Based on the best scientific and commercial data available, 
including the Biological Review Team's (BRT's) status review report, we 
conclude that listing the ribbon seal as threatened or endangered under 
the ESA is not warranted at this time. We also announce the 
availability of the ribbon seal status review report.

DATES: This listing determination was made on July 10, 2013.

ADDRESSES: The ribbon seal status review report, as well as this 
listing determination, can be obtained via the internet at https://alaskafisheries.noaa.gov/. Supporting documentation used in preparing 
this listing determination is available for public inspection, by 
appointment, during normal business hours at the office of NMFS Alaska 
Region, Protected Resources Division, 709 West Ninth Street, Room 461, 
Juneau, AK 99801. This documentation includes the status review report, 
information provided by the public, and scientific and commercial data 
gathered for the status review.

FOR FURTHER INFORMATION CONTACT: Tamara Olson, NMFS Alaska Region, 
(907) 271-5006; Jon Kurland, NMFS Alaska Region, (907) 586-7638; or 
Marta Nammack, NMFS Office of Protected Resources, (301) 427-8469.

SUPPLEMENTARY INFORMATION:

Background

    On December 20, 2007, we received a petition from the Center for 
Biological Diversity (CBD) to list the ribbon seal as a threatened or 
endangered species under the ESA, primarily due to concern about 
threats to this species' habitat from climate change and

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resultant loss of sea ice. The Petitioner also requested that critical 
habitat be designated for ribbon seals concurrently with listing under 
the ESA. On March 28, 2008, we published a 90-day finding (73 FR 16617) 
in which we determined that the petition presented substantial 
information indicating that the petitioned action may be warranted and 
initiated a status review of the ribbon seal. On December 30, 2008, we 
published our 12-month finding and determined that listing of the 
ribbon seal was not warranted (73 FR 79822).
    On September 3, 2009, CBD and Greenpeace, Inc. (collectively, 
``Petitioners'') filed a complaint in the U.S. District Court for the 
Northern District of California challenging our 12-month finding. On 
December 21, 2010, after considering cross-motions for summary 
judgment, the Court denied the Petitioners' motion for summary judgment 
and granted NMFS's cross-motion. The Petitioners filed a notice of 
appeal of this judgment to the Ninth Circuit Court of Appeals on 
January 18, 2011.
    Information became available since publication of the December 30, 
2008, 12-month finding that had potential implications for the status 
of the ribbon seal relative to the listing provisions of the ESA, 
including new data on ribbon seal movements and diving, as well as a 
modified threat-specific approach to analyzing the ``foreseeable 
future'' which we used in status reviews for spotted (Phoca largha), 
ringed (Phoca hispida), and bearded seals (Erignathus barbatus) that we 
completed subsequent to the ribbon seal status review (75 FR 65239, 
October 22, 2010; 77 FR 76706 and 77 FR 76740, December 28, 2012). In 
consideration of this information, on August 30, 2011, we agreed to 
initiate a new status review and issue a determination on whether 
listing the ribbon seal as threatened or endangered is warranted and 
submit a determination to the Office of the Federal Register by 
December 10, 2012. In addition, under the terms of this agreement, 
following publication of the new listing determination in the Federal 
Register, the Petitioners will file a motion for voluntary dismissal of 
its appeal of the December 21, 2010, judgment. We announced the 
initiation of this status review on December 13, 2011 (76 FR 77467). 
Subsequently, NMFS and the other parties to this agreement agreed to 
change the 12-month deadline to July 10, 2013.
    The 2013 status review report for the ribbon seal (Boveng et al., 
2013) is a compilation of the best scientific and commercial data 
available concerning the status of the species, including 
identification and assessment of the past, present, and foreseeable 
future threats to the species. The BRT that prepared this report was 
composed of eight marine mammal biologists, two fishery biologists, and 
a climate scientist from NMFS's Alaska and Southwest Fisheries Science 
Centers and NOAA's Pacific Marine Environmental Laboratory. The status 
review report underwent independent peer review by three scientists 
with expertise in marine mammal biology and ecology, including 
specifically ribbon seals.

ESA Statutory, Regulatory, and Policy Provisions

    Section 3 of the ESA defines a ``species'' as ``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.'' 
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). Under section 4(a)(1) of the ESA, we must determine 
whether a species is threatened or endangered because of any one or a 
combination of the following factors: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) inadequacy of 
existing regulatory mechanisms; or (E) other natural or human-made 
factors affecting its continued existence. We are to make this 
determination 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 being made by states or foreign 
governments to protect the species. In judging the efficacy of 
protective efforts not yet implemented or not yet shown to be 
effective, we rely on the joint NMFS and FWS Policy for Evaluating 
Conservation Efforts When Making Listing Decisions (68 FR 15100; March 
28, 2003).
    Two key tasks are associated with conducting an ESA status review. 
The first is to identify the taxonomic group under consideration; and 
the second is to conduct an extinction risk assessment which will be 
used to determine whether the petitioned species is threatened or 
endangered.
    To be considered for listing under the ESA, a group of organisms 
must constitute a ``species,'' which section 3(16) of the ESA defines 
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.'' The term ``distinct 
population segment'' (DPS) is not commonly used in scientific 
discourse, so the U.S. Fish and Wildlife Service (FWS) and NMFS 
developed the ``Policy Regarding the Recognition of Distinct Vertebrate 
Population Segments Under the Endangered Species Act'' to provide a 
consistent interpretation of this term for the purposes of listing, 
delisting, and reclassifying vertebrates under the ESA (61 FR 4722; 
February 7, 1996). We describe and use this policy below to guide our 
determination of whether any population segments of this species meet 
the DPS criteria established in the policy.
    The foreseeability of a species' future status is case specific and 
depends upon both the foreseeability of threats to the species and 
foreseeability of the species' response to those threats. When a 
species is exposed to a variety of threats, each threat may be 
foreseeable over a different time frame. For example, threats stemming 
from well-established, observed trends in a global physical process may 
be foreseeable on a much longer time horizon than a threat stemming 
from a potential, though unpredictable, episodic process such as an 
outbreak of disease that may never have been observed to occur in the 
species.
    Since completing the 2008 status review of the ribbon seal (Boveng 
et al., 2008), with its climate impact analysis, NMFS scientists have 
revised their analytical approach to the foreseeability of threats due 
to climate change and responses to those threats, adopting a more 
threat-specific approach based on the best scientific and commercial 
data available for each respective threat. For example, because the 
climate projections in the Intergovernmental Panel on Climate Change's 
(IPCC's) Fourth Assessment Report (AR4; IPCC, 2007) extend through the 
end of the century (and we note the IPCC's Fifth Assessment Report 
(AR5), due in 2014,

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will extend even farther into the future), our updated analysis of 
ribbon seals used the same models to assess impacts from climate change 
through 2100, which is consistent with the time horizon used in our 
recent examination of climate change effects for spotted, ringed, and 
bearded seals. We continue to recognize that the farther into the 
future the analysis extends, the greater the inherent uncertainty, and 
we incorporated that limitation into our assessment of the threats and 
the species' response. Not all potential threats to ribbon seals are 
climate related, and therefore not all can be regarded as foreseeable 
through the end of the 21st century. For example, evidence of 
morbillivirus (phocine distemper) exposure in sea otters has recently 
been reported from Alaska (Goldstein et al., 2009). Thus, distemper may 
be considered a threat to ribbon seals, but the time frame of 
foreseeability of an inherently episodic and novel threat is difficult 
or impossible to establish. Similarly, factors that influence the 
magnitude and foreseeability of threats from oil and gas industry 
activities are difficult to predict beyond a few decades into the 
future because of dynamic and changing trends in the global oil and gas 
industry. These are only two examples of many potential threats without 
clear horizons of foreseeability. Therefore, although it is intuitive 
that foreseeability varies among threats facing ribbon seals, it is 
impractical to explicitly specify separate horizons of foreseeability 
for some of them (i.e., there is no consensus among BRT members, let 
alone a broader community of scientists).
    Faced with the challenge of applying the ``foreseeable future'' 
terminology of the ESA to a comprehensive scientific assessment of 
extinction risk, the BRT opted to evaluate threats and demographic 
risks on two time frames within the period defined by the horizon of 
foreseeability for the threats of primary concern, namely those 
stemming from greenhouse gas (GHG) emissions: (1) the period from now 
to mid-century, corresponding to the time over which the IPCC considers 
climate warming to be essentially determined by past and near-future 
emissions; and (2) the period from now to the end of the century, a 
period in which sustained warming is anticipated under all plausible 
emissions scenarios, but the magnitude of that warming is more 
uncertain. Consideration of threats (and demographic risks) within 
these two time frames was intended to provide a sense of how the BRT's 
judgment of all the threats and the level of certainty about those 
threats may vary over the period of foreseeability for climate-related 
threats. We agree with this threat-specific approach, which creates a 
more robust analysis of the best scientific and commercial data 
available. It is also consistent with the memorandum issued by the 
Department of Interior, Office of the Solicitor, regarding the meaning 
of the term ``foreseeable future'' (Opinion M-37021; January 16, 2009).
    NMFS and FWS recently published a draft policy to clarify the 
interpretation of the phrase ``significant portion of the range'' in 
the ESA definitions of ``threatened'' and ``endangered'' (76 FR 76987; 
December 9, 2011). The draft policy provides that: (1) If a species is 
found to be endangered or threatened in only a significant portion of 
its range, the entire species is listed as endangered or threatened, 
respectively, and the ESA's protections apply across the species' 
entire range; (2) a portion of the range of a species is 
``significant'' if its contribution to the viability of the species is 
so important that, without that portion, the species would be in danger 
of extinction; (3) the range of a species is considered to be the 
general geographical area within which that species can be found at the 
time FWS or NMFS makes any particular status determination; and (4) if 
the species is not endangered or threatened throughout all of its 
range, but it is endangered or threatened within a significant portion 
of its range, and the population in that significant portion is a valid 
DPS, we will list the DPS rather than the entire taxonomic species or 
subspecies.
    The Services are currently reviewing public comment received on the 
draft policy. While the Services' intent is to establish a legally 
binding interpretation of the term ``significant portion of the 
range,'' the draft policy does not have legal effect until such time as 
it may be adopted as final policy. Here, we apply the principles of 
this draft policy as non-binding guidance in evaluating whether to list 
the ribbon seal under the ESA. If the policy changes in a material way, 
we will revisit the determination and assess whether the final policy 
would result in a different outcome.

Species Information

    A thorough review of the taxonomy, life history, and ecology of the 
ribbon seal is presented in the status review report (Boveng et al., 
2013). We provide a summary of this information below.

Description

    The ribbon seal is a strikingly[hyphen]marked member of the family 
Phocidae that primarily inhabits the Sea of Okhotsk and the Bering and 
Chukchi seas. This species gets its common and specific (fasciata) 
names from the distinctive band or ``ribbon'' pattern exhibited by 
mature individuals, which consists of four light-colored ribbons on a 
background of darker pelage. Ribbon seals are medium-sized when 
compared to the other three species of ice-associated seals in the 
North Pacific; they are larger than ringed seals, smaller than bearded 
seals, and similar in size to spotted seals. Ribbon seals have 
specialized physiological features that are likely adaptations for deep 
diving and fast swimming, including the highest number and volume of 
erythrocytes (red blood cells) and the highest blood hemoglobin 
(oxygen-transport protein in red blood cells) of all seals, as well as 
larger internal organs than those of other seals.

Distribution, Habitat Use, and Movements

    The distribution of ribbon seals is restricted to the northern 
North Pacific Ocean and adjoining sub-Arctic and Arctic seas, where 
they occur most commonly in the Sea of Okhotsk and Bering Sea. Habitat 
selection by ribbon seals is seasonally related to specific life 
history events that can be broadly divided into two periods: (1) spring 
and early summer (March-June) when whelping, nursing, breeding, and 
molting all take place in association with sea ice on which the seals 
haul out; and (2) mid-summer through fall and winter when ribbon seals 
rarely haul out and are mostly not associated with ice.
    In spring and early summer, ribbon seal habitat is closely 
associated with the distribution and characteristics of seasonal sea 
ice. Ribbon seals are strongly associated with sea ice during the 
breeding season and not known to breed on shore (Burns, 1970; Burns, 
1981). During this time, ribbon seals are concentrated in the ice front 
or ``edge-zone'' of the seasonal pack ice, to as much as 150 km north 
of the southern ice edge (Burns, 1970; Fay, 1974; Burns, 1981; Braham 
et al., 1984; Lowry, 1985; Kelly, 1988). Shustov (1965a) observed that 
ribbon seals were most abundant in the northern part of the ice front 
and this north-south gradient has been observed in several other 
studies as well. Shustov (1965a) also found that ribbon seal abundance 
increased only with ice concentration and was unaffected by ice type, 
shape, or form. This is in contrast to most studies which show that 
ribbon seals generally prefer new, stable, white, clean, hummocky ice 
floes, invariably with an even surface; it is rare to observe them on 
dirty or

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discolored floes, except when the ice begins to melt and haul-out 
options are more limited (Heptner et al., 1976; Burns, 1981; Ray and 
Hufford, 2006). Ribbon seals also seem to choose moderately thick ice 
floes (Burns, 1970; Fay, 1974; Burns, 1981). These types of ice floes 
are often located at the inner zone of the ice front and rarely occur 
near shore, which may explain why ribbon seals are typically found on 
ice floes far away from the coasts during the breeding season (Heptner 
et al., 1976).
    In most years, the Bering Sea pack ice expands to or near the 
southern edge of the continental shelf. Most of this ice melts by early 
summer. However, Burns (1969) described a zone of sea ice that remains 
in the central Bering Sea until melting around mid-June. Satellite 
imagery has verified the presence and persistence of this zone of ice 
and has shown that it is located relatively close to the edge of the 
continental shelf. Ribbon seals are numerous in this area, which is an 
extremely productive region that likely provides rich foraging grounds 
(Burns, 1981). Prey availability could strongly influence whelping 
locations because females probably feed actively during the nursing 
period (Lowry, 1985). In spring and early summer, ribbon seals are 
usually found in areas where water depth does not exceed 200 m, and 
they appear to prefer to haul out on ice that is near or over deeper 
water, indicating their preference for the continental shelf slope 
(Heptner et al., 1976). The seasonal dive-depth patterns of a small 
sample of ribbon seals monitored by satellite telemetry are consistent 
with a preference for feeding on the continental shelf slope (National 
Marine Mammal Laboratory (NMML), unpublished data).
    During May and June, ribbon seals spend much of the day hauled out 
on ice floes while weaned pups develop self-sufficiency and adults 
complete their molt. As the ice melts, seals become more concentrated, 
with at least part of the Bering Sea population moving towards the 
Bering Strait and the southern part of the Chukchi Sea. This suggests 
that proximity to the shelf slope and its habitat characteristics 
(e.g., water depth, available prey) become less important, at least 
briefly around the molting period when feeding is likely reduced.
    Although ribbon seals are strongly associated with sea ice during 
the whelping, breeding, and molting periods, they do not remain so 
after molting is complete. During summer, the ice melts completely in 
the Sea of Okhotsk, and by the time the Bering Sea ice recedes north 
through the Bering Strait, there are usually only a small number of 
ribbon seals hauled out on the ice. Significant numbers of ribbon seals 
are only seen again in winter when the sea ice reforms. The widespread 
distribution and diving patterns of ribbon seals monitored by satellite 
telemetry suggest that these seals are able to exploit many different 
environments and can tolerate a wide range of habitat conditions in 
mid-summer through winter.

Life History

    The rates of survival and reproduction are not well known, but the 
normal lifespan of a ribbon seal is probably 20 years, with a maximum 
of perhaps 30 years. Ribbon seals become sexually mature at 1 to 5 
years of age, probably depending on environmental conditions.
    Whelping in the Bering Sea and northern Sea of Okhotsk occurs on 
seasonal pack ice over a period of about 5-6 weeks, ranging from late 
March to mid-May with a peak in early to mid-April (Tikhomirov, 1964; 
Shustov, 1965b; Burns, 1981), perhaps with some annual variation 
related to weather and ice conditions (Burns, 1981). The timing of 
whelping in the southern Sea of Okhotsk and Tartar Straight is not 
known, but may occur earlier, during March-April (Tikhomirov, 1966). 
Pups are nursed for 3-4 weeks (Tikhomirov, 1968; Burns, 1981), during 
which time mothers continue to feed, sometimes leaving their pups 
unattended on the ice while diving. Most pups are weaned by mid-May, 
which occurs when the mother abandons the pup (Tikhomirov, 1964). 
Breeding occurs shortly after weaning.
    Ribbon seals molt their coat of hair annually between late March 
and July, with the timing of an individual's molt depending upon its 
age and reproductive status (Burns, 1981). Sexually mature seals begin 
molting around the time of mating, and younger seals begin molting 
earlier.

Feeding Habits

    The year-round food habits of ribbon seals are not well known, in 
part because almost all information about ribbon seal diet is from the 
months of February through July, and particularly March through June. 
Ribbon seals primarily consume pelagic (open ocean) and nektobenthic 
(swim near the seafloor) prey, including demersal (dwell near the 
seafloor) fishes, squids, and octopuses. Walleye pollock (Theragra 
chalcogramma) is a primary prey item, at least during spring, in both 
the Bering Sea and the Sea of Okhotsk. Other fish prey species found in 
multiple studies were Arctic cod (Boreogadus saida), Pacific cod (Gadus 
macrocephalus), saffron cod (Eleginus gracilis), Pacific sand lance 
(Ammodytes hexapterus), smooth lumpsucker (Aptocyclus ventricosus), 
eelpouts, capelin (Mallotus villosus), and flatfish species. Several 
species of both squid and octopus make up a significant part of ribbon 
seal diets throughout their range. Some studies have also found that 
crustaceans are an important part of the ribbon seal's diet. Several 
studies indicate that pups and juveniles mainly feed on small 
crustaceans and adults primarily consume fish and nektobenthos, like 
walleye pollock, octopuses, and squids.

Current Abundance and Trends

    Ribbon seal abundance estimates have been based on catch data from 
sealing vessels, aerial surveys, and shipboard observations when seals 
are hauled out on the ice to whelp and molt. Russian estimates of 
Bering Sea abundance and trends were determined in the early 1960s from 
commercial catch data. Aerial survey data were often inappropriately 
extrapolated to the entire area based on densities and ice 
concentration estimates without behavioral research to determine 
factors affecting habitat selection. Very few details of the aerial 
survey methods or data have been published, so it is difficult to judge 
the reliability of the reported numbers. No suitable behavior data have 
been available to correct for the proportion of seals in the water at 
the time of surveys. Current research is just beginning to address 
these limitations and no current and reliable abundance estimates have 
been published.
    Aerial surveys were conducted in portions or all of the ice-covered 
Bering Sea east of the international date line by NMML in 2003 
(Simpkins et al., 2003), 2007 (Cameron and Boveng, 2007; Moreland et 
al., 2008; Ver Hoef et al., 2013), 2008, and 2012. A partial population 
estimate of 61,100 ribbon seals in the eastern and central Bering Sea 
(95 percent confidence interval: 35,200-189,300) was derived from the 
surveys conducted in 2007 (Ver Hoef et al., 2013). Using restrictive 
assumptions, the BRT scaled this number according to distributions of 
ribbon seal breeding areas in 1987 (Fedoseev et al., 1988), to produce 
total Bering Sea estimates ranging from 121,000 to 235,000. Similar 
scaling based on a range-wide distribution presented by Fedoseev (1973) 
produced Bering Sea, Sea of Okhotsk, and total-range estimates of 
143,000, 124,000, and 267,000, respectively. Based on

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application of the 95 percent confidence interval reported by Ver Hoef 
et al. (2013) to the scaled range-wide estimate of 267,000 animals, the 
total range-wide abundance estimate could be as low as 154,000 or as 
high as 827,000. Aerial surveys conducted during the spring of 2012 and 
2013 in the Bering Sea and Sea of Okhotsk included many sightings of 
ribbon seals, and preliminary analyses suggest that abundance estimates 
derived from these data will be higher than those obtained in the more 
limited survey reported by Ver Hoef et al. (2013).
    Within the scaled range-wide estimate of 267,000, the Sea of 
Okhotsk component of about 124,000 is lower than all but one previous 
estimate for that region, and dramatically lower than the most recent 
estimates from Russian surveys during 1979-1990, which ranged from 
410,000 to 630,000 (Fedoseev, 2000). This difference may reflect a 
failure of assumptions rather than a population decline. The BRT's 
estimate for the Sea of Okhotsk was derived from a recent density 
estimate in the Bering Sea, scaled by a much generalized distribution 
from the 1960s of seals in the Sea of Okhotsk. The density estimate for 
the Bering Sea may simply not be applicable to the distribution, and 
vice versa. Lacking details about the Russian survey methods that 
produced the larger numbers, and lacking any data on abundance in 
Russian waters more recent than 1990, the BRT opted to use the smaller 
number for the Sea of Okhotsk.
    The BRT concluded that the current population trend of ribbon seals 
cannot be determined, but that strong upward or downward trends in the 
recent past seem unlikely. High rates of sightings in recent surveys, 
and reports from Alaska Native subsistence hunters (Quakenbush and 
Sheffield, 2007) that indicate stable or rising numbers, suggest that 
there has not been a recent dramatic decline.

Species Delineation

    Under our DPS policy (61 FR 4722; February 7, 1996), two elements 
are considered in a decision regarding the potential identification of 
a DPS: (1) the discreteness of the population segment in relation to 
the remainder of the species or subspecies to which if belongs; and (2) 
the significance of the population segment to the species or subspecies 
to which is belongs. If a population segment is discrete and 
significant (i.e., it is a DPS) its evaluation for threatened or 
endangered status will be based on the ESA's definitions of those terms 
and a review of the factors enumerated in ESA section 4(a)(1).
    A population segment of a vertebrate species may be considered 
discrete if it satisfies either one of the following conditions: (1) 
``It is markedly separated from other populations of the same taxon as 
a consequence of physical, physiological, ecological, or behavioral 
factors. Quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation''; or (2) ``It is 
delimited by international governmental boundaries within which 
differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D)'' of the ESA.
    With respect to discreteness criterion 1, the BRT concluded, and we 
concur, that although there are two main breeding areas for ribbon 
seals, one in the Sea of Okhotsk and one in the Bering Sea, there is 
currently no evidence of discrete populations on which to base a 
separation into DPSs (see Boveng et al., 2013 for additional details). 
As noted above, under the DPS policy, discreteness of a DPS may also be 
considered based on delimitation by international governmental 
boundaries within which differences in control of exploitation, 
management of habitat, conservation status, or regulatory mechanisms 
exist that are notable in light of section 4(a)(1)(D) of the ESA. 
Ribbon seals occur throughout a vast area of international waters and 
waters under the jurisdiction of the United States, the Russian 
Federation, and the State of Alaska. The primary breeding locations are 
in the territorial seas and exclusive economic zones of the United 
States and the Russian Federation. There are differences between the 
United States and the Russian Federation in the control of 
exploitation, management of habitat, and regulatory mechanisms that 
influence ribbon seal conservation status. For example, as noted in the 
threats assessment below, and discussed in more detail in the status 
review report, measures to control exploitation of ribbons seals appear 
to be substantially different between the two nations. While commercial 
hunting for ribbon seals is not allowed in the United States, such 
harvests are permitted by the Russian Federation. Regulations which 
govern commercial harvest of ice seals in Russia are over 20 years old 
and quotas on ribbon seals in Russian waters would allow large 
harvests. It is thus unclear what regulatory mechanisms are currently 
in place to ensure that potential commercial harvests remain within 
sustainable levels. Still, current commercial harvest levels remain low 
because of poor economic viability, and unless efforts to develop new 
uses and markets for seal products are successful, commercial harvest 
of ribbon seals is unlikely to increase in the near future. As 
discussed above, downward trends in ribbon seal population abundance in 
the recent past seem unlikely, which suggests that the differences in 
management between the United States and the Russian Federation are not 
significant, and the potential for this to change is uncertain. We find 
that the differences in management do not rise to a level that provides 
a sufficient basis to justify the use of international boundaries to 
satisfy the discreteness criterion of our DPS Policy (i.e., we found 
that inadequacy of existing regulatory mechanisms does not pose a 
significant threat to the persistence of the ribbon seal and is not 
likely to do so in the foreseeable future). In addition, we note that 
the maritime boundary between the United States and the Russian 
Federation does not specifically delimit the Sea of Okhotsk breeding 
area. Rather, this international boundary divides the eastern and 
central Bering Sea portion of the ribbon seal range (i.e., U.S.) from 
the western Bering Sea and Sea of Okhotsk (i.e., Russian) portion. In 
other words, delimitation by international governmental boundaries 
would place the division in the Bering Sea, where the distribution of 
ribbon seal breeding areas appears to be continuous and where ribbon 
seals move routinely without regard to the maritime boundary. We 
therefore conclude that there are no population segments that satisfy 
the discreteness criteria of our DPS Policy. Since there are no 
discrete population segments, we cannot take the next step of 
determining whether any discrete population segment is significant to 
the taxon to which it belongs.

Summary of Factors Affecting the Ribbon Seal

    The following sections discuss threats to the ribbon seal under 
each of the five factors specified in Section 4(a)(1) of the ESA and 50 
CFR 424. The reader is also directed to section 4.2 of the status 
review report (Boveng et al., 2013) for a more detailed discussion of 
the factors affecting the ribbon seal. As discussed above, the data on 
ribbon seal abundance and trends in abundance are very imprecise, and 
there is little basis for quantitatively linking projected 
environmental conditions or other factors to ribbon seal survival or 
reproduction. Our risk assessment therefore primarily evaluated 
important habitat features and was based upon the

[[Page 41376]]

best available scientific and commercial data and the expert opinion of 
the BRT members.
    A structured approach was used to elicit the BRT members' judgment 
about the significance of the threats facing ribbon seals (excluding 
Factor D). The primary threats identified were grouped by each ESA 
Section 4(a)(1) factor, and each individual threat was scored for its 
significance, in two components (each on a 5-level scale): (1) extent 
(portion of the population that would experience reduced survival or 
reproductive success if the threat condition were to occur), and (2) 
likelihood of occurrence within a specified time period in the 
foreseeable future. For many threats, such as oil spills, there are a 
broad range of plausible extents with little or no consensus about what 
scenarios are most plausible. Consequently, for such threats, the 
process of judging significance was often an iterative one in which 
extent was not always judged before likelihood, and vice-versa. Because 
of potential differences in the strengths of the threats between the 
Bering Sea and Sea of Okhotsk, the BRT assigned scores separately for 
these two portions of the ribbon seal's range.
    Each BRT member assigned extent and likelihood scores for each 
threat for the time period of now to mid-century, and now to the year 
2100. Consideration of threats within these two time frames was 
intended to provide a sense of how the BRT's judgment of all the 
threats and the level of certainty about those threats may vary over 
the period of foreseeability for climate-related threats. For the 
period now to 2100, a threat score was also computed for each threat by 
multiplying the extent score by the likelihood score The range of these 
threat scores was divided into significance categories of ``low'' (1-
4), ``moderate'' (5-10), ``high'' (11-15), ``very high'' (16-20), and 
``extreme'' (21-25). Using the same scale as for the threat scores, 
each BRT member also considered the individual threat scores in 
assigning an overall score for each ESA section 4(a)(1) factor 
(excluding Factor D). These overall factor scores reflect the BRT's 
judgment about the significance of each factor as a whole, including 
cumulative impacts. The average score and range of scores among BRT 
members are reported in the status review report. In this listing 
determination we summarize the average threat and overall factor 
scores. Additional details are contained in the status review report.

A. Present or Threatened Destruction, Modification, or Curtailment of 
the Species' Habitat or Range

    The main concerns about the conservation status of the ribbon seal 
stem from the likelihood that its sea ice habitat has been modified by 
the warming climate and, more so, that the scientific consensus 
projections are for continued and perhaps accelerated warming in the 
foreseeable future which could make large areas of habitat less 
suitable for ribbon seals. A second concern, related by the common 
driver of carbon dioxide (CO2) emissions, is the 
modification of habitat by ocean acidification, which may alter prey 
populations and other important aspects of the marine environment. A 
reliable assessment of the future conservation status of ribbon seals, 
therefore, requires a focus on the observed and projected changes in 
sea ice, ocean temperature, ocean pH (acidity), and associated changes 
in ribbon seal prey species. The threats associated with impacts of the 
warming climate on the habitat of ribbon seals, to the extent that they 
may pose risks to these seals, are expected to manifest throughout the 
current breeding and molting range (for sea ice related threats) or 
throughout the entire range (for ocean warming and acidification) of 
the ribbon seal.

Effects of Climate Change on Annual Formation of the Ribbon Seal's Sea 
Ice Habitat

    Unlike the Arctic Ocean, where some sea ice is present year round 
(i.e., multi-year ice), the ice in the Bering Sea and Sea of Okhotsk is 
seasonal and forms every winter as first-year ice. The main 
thermodynamic physical influence at high latitudes is the cold and 
darkness that occurs in winter. Despite the recent dramatic reductions 
in Arctic Ocean ice extent during summer, the sea ice in the northern 
Bering Sea and Sea of Okhotsk is expected to continue forming annually 
in winter for the foreseeable future, with large interannual variations 
in sea ice extent and duration. The future central Arctic will also 
continue to be an ice[hyphen]covered sea in winter, but will contain 
more first[hyphen]year sea ice than multi[hyphen]year ice.
    Ice extent in marginal seas such as the Bering Sea is characterized 
not by summer minima, since these seas have been ice[hyphen]free in 
summer throughout recorded history, but rather by winter maxima. 
Freezing conditions in the northern Bering Sea persist from December 
through April. Mean monthly maximum temperatures at Nome, Alaska are -
3[deg]C or below for all months November through April. Freezing rather 
than thawing should still predominate in these months even if a 
hypothesized ~3[deg]C global warming signal is realized. The result is 
that the seasonal formation of sea ice in the northern Bering Sea and 
Sea of Okhotsk is substantially decoupled from the summer ice extent in 
the Arctic Ocean, and is expected to continue annually through the 
foreseeable future, along with large interannual variations in extent 
and duration of persistence.

IPCC Model Projections

    Comprehensive Atmosphere-Ocean General Circulation Models (AOGCMs) 
are the major objective tools that scientists use to understand the 
complex interaction of processes that determine future climate change. 
The IPCC used the simulations from about two dozen AOGCMs developed by 
17 international modeling centers as the basis for the AR4 (IPCC, 
2007). The analysis and synthesis of information presented by the IPCC 
in its AR4 represents the scientific consensus view on the causes and 
future of climate change. The AR4 used a range of future GHG emissions 
produced under six illustrative ``marker'' scenarios from the Special 
Report on Emissions Scenarios (SRES) (IPCC, 2000) to project plausible 
outcomes under clearly-stated assumptions about socio-economic factors 
that will influence the emissions. Conditional on each scenario, the 
best estimate and likely range of emissions were projected through the 
end of the 21st century. It is important to note that these scenarios 
do not contain explicit assumptions about the implementation of 
agreements or protocols on emission limits beyond current mitigation 
policies and related sustainable development practices.
    More recent climate model projection experiments are in progress in 
preparation for publication of the IPCC's Fifth Assessment Report (AR5) 
in 2014. However, the AR5 is not yet available. Therefore, the BRT used 
the modeling results from the AR4 in the status review. Knutti and 
Sedlacek (2012) found that projected global temperature change from the 
new models that will be used in the AR5 is remarkably similar to that 
from those models used in the AR4 after accounting for the different 
underlying emissions scenarios, and the spatial patterns of temperature 
and precipitation change were also very consistent. The AOGCMs provide 
reliable projections because they are built on well-known dynamical and 
physical principles, and they simulate quite well many large scale 
aspects of present-day conditions. However, the coarse resolution of 
most

[[Page 41377]]

current climate models dictates careful application on small scales in 
heterogeneous regions, such as along coastlines.
    There are three main contributors to divergence in AOGCM climate 
projections: large natural variations, across-model differences, and 
the range in emissions scenarios. The first of these, variability from 
natural variation, can be incorporated by averaging the projections 
over decades, or, preferably, by forming ensemble averages from several 
runs of the same model. The second source of variation, across-model 
differences, results from differences among models in factors such as 
spatial resolution. This variation can be addressed and mitigated in 
part by using the ensemble means from multiple models.
    The third source of variation arises from the range in plausible 
emissions scenarios. Conditions such as surface air temperature and sea 
ice area are linked in the IPCC climate models to GHG emissions by the 
physics of radiation processes. When CO2 is added to the 
atmosphere, it has a long residence time and is only slowly removed by 
ocean absorption and other processes. Based on IPCC AR4 climate models, 
expected increases in global warming--defined as the change in global 
mean surface air temperature (SAT)--by the year 2100 depend strongly on 
the assumed emissions of CO2 and other GHGs, versus natural 
variations across-model differences (IPCC, 2007). By contrast, global 
warming projected out to about 2040-2050 will be primarily due to 
emissions that have already occurred and those that will occur over the 
next decade. Thus, conditions projected to mid-century are less 
sensitive to assumed future emission scenarios than are longer-term 
projections to the end of the century. Uncertainty in the amount of 
warming out to mid-century is primarily a function of model-to-model 
differences in the way that the physical processes are incorporated, 
and this uncertainty can be addressed in predicting ecological 
responses by incorporating the range in projections from different 
models. Because the current consensus is to treat all SRES emissions 
scenarios as equally likely, one option for representing the full range 
of variability in potential outcomes would be to project from any model 
under all of the six ``marker'' scenarios. This can be impractical in 
many situations, so the typical procedure for projecting impacts is to 
use an intermediate scenario to predict trends, or one intermediate and 
one extreme scenario to represent a significant range of variability.
    There is no universal method for combining AOGCMs for climate 
projections, and there is no one best model. The approach taken by the 
BRT for selecting the models used to project future sea ice in the 
status review report is summarized below.

Data and Analytical Methods

    Many of the anticipated effects of GHG emissions have been 
projected through the end of the 21st century, subject to certain 
inputs and assumptions, and these projections currently form the most 
widely accepted version of the best available data about future 
environmental conditions. In our risk assessment for ribbon seals, we 
therefore considered climate model projections through the end of the 
21st century to analyze the threats stemming from climate change.
    The IPCC model simulations used in the BRT analyses were obtained 
from the Program for Climate Model Diagnosis and Intercomparison 
(PCMDI) on-line (at https://www-pcmdi.llnl.gov/). Wang and Overland 
(2009) identified a subgroup of six of these models that met 
performance criteria for reasonably reproducing the observed magnitude 
of the seasonal cycle of Northern Hemisphere sea ice extent. Climate 
models generally perform better on continental or larger scales, but 
because habitat changes are not uniform throughout the hemisphere, 
using similar performance criteria, the BRT further evaluated each of 
these six IPCC models independently on their performance at reproducing 
the observed seasonal cycle of sea ice extent during April and May in 
each of four regions--the Sea of Okhotsk, western Bering Sea, eastern 
Bering Sea, and Chukchi Sea.
    All six of the models met the performance criteria for sea ice in 
the Chukchi Sea and four of the six models met the criteria for the 
eastern Bering Sea. Only one of the six models was in reasonable 
agreement with observations for the western Bering Sea; this single 
model was therefore used to project sea ice in this region with caveats 
about the reliability as noted below. Due to model deficiencies and the 
small size of the Sea of Okhotsk region relative to the spatial 
resolution of the climate models, none of the models met the 
performance criteria for this region. Instead, for the Sea of Okhotsk, 
comparison of SAT projections with current climate conditions was 
considered. Thirteen models, which were selected based on their ability 
to represent the climate of the North Pacific (Overland and Wang, 
2007), were used to project future SATs in the Sea of Okhotsk. Whether 
future monthly mean SATs are above or below the freezing point of sea 
water provides a reasonable indicator of the presence or absence of sea 
ice. Projections of SATs for the Sea of Okhotsk were considered under 
both a medium and a high emissions scenario; similarly, model output 
under both of these emissions scenarios was considered for the other 
three regions.
    While our inferences about future regional ice conditions are based 
upon the best available scientific and commercial data, we recognize 
that there are uncertainties associated with predictions based on 
hemispheric projections or indirect means. We also note that judging 
the timing of onset of potential impacts to ribbons seals is 
complicated by the coarse resolution of the IPCC models. For example, 
in June 2008 the NOAA ship Oscar Dyson encountered a field of ice with 
numerous ribbon and spotted seals near St. Matthew Island in an area 
where no ice was visible on the relatively high resolution (12.5 km) 
satellite images of sea ice for that day. Nevertheless, NMFS concluded 
that the models reflect reasonable assumptions regarding habitat 
alterations to be faced by ribbon seals in the foreseeable future.

Regional Sea Ice Projections

    The projections indicate that within this century there will be no 
significant ice reductions in the Chukchi Sea in winter through early 
spring (January to May). A downward trend in ice extent is evident in 
the Chukchi Sea in June toward the end of the century, by which time 
the difference between the emissions scenarios becomes a major 
contributor to the trends. Interannual variability of the model 
projections is larger in the Chukchi Sea after mid-century. In the 
eastern Bering Sea, a gradual downward trend in the sea ice extent is 
apparent over the century in March through May, albeit with a large 
degree of interannual variability. The average sea ice extent in the 
eastern Bering Sea during these months is projected to be at 58 percent 
of the present day value by 2050, and at 37 percent of the present day 
value by 2075. As discussed above, ice projections were only available 
for the western Bering Sea from a single model, so the results must be 
interpreted in the context of possibly large bias and lack of model-to-
model variation. Compared with observations, this model overestimated 
sea ice extent in both March and April, but performed reasonably well 
for May and June. The model projected a rapid decline in sea ice extent 
in the western Bering Sea over the first half of this century in

[[Page 41378]]

March and April, then relative stability to the end of the century. The 
model projected that the western Bering Sea will continue to have ice 
in March and April through nearly the end of the 21st century; however, 
the average sea ice extent in the latter half of this century in these 
months is projected to be approximately 25 percent of the present-day 
extent. The projection for May indicates that there will commonly be 
years when the western Bering Sea will have little or no ice beyond 
mid-century. Mapped projections of sea ice concentrations in the two 
Bering Sea regions indicate that by mid-century and beyond, the Bering 
Sea can be expected to have essentially no ice during May in some 
years, and by 2090 May sea ice can be expected only in the northern 
Bering Sea.
    As noted above, none of the IPCC models performed satisfactorily at 
projecting ice for the Sea of Okhotsk, and so projected SATs were 
considered relative to current climate conditions as a proxy to predict 
sea ice extent and duration. The Sea of Okhotsk lies to the southwest 
of the Bering Sea and thus can be expected to have earlier radiative 
heating in spring. However, this region is dominated by cold 
continental air masses and offshore flow for much of the winter and 
spring. Therefore, the present seasonal cycle of the formation of 
first-year sea ice during winter is expected to continue annually in 
the foreseeable future. Based on the temperature proxies, a 
continuation of sea ice formation or presence is expected for March 
through the end of this century, though the ice may be limited to the 
northern portion of this region in most years after mid-century. 
Conditions for sea ice in April are likely to be limited to the far 
northern reaches of the Sea of Okhotsk, or non-existent if the 
projected warming occurs by 2100. Recent climate data indicate that 
during May, sea ice has warmed to the melting point throughout the Sea 
of Okhotsk region.
    In summary, within the ribbon seal's range large areas of annual 
sea ice are expected to form and persist through April in most years 
throughout this century. However, in the Sea of Okhotsk conditions for 
sea ice in April are likely to be limited to the far northern reaches 
or non-existent if the projected warming occurs by 2100. In May, ice is 
projected to continue to occur in the Bering Sea in most years through 
mid-century, but in the latter half of the century many years are 
expected to have little or no ice. Sea ice extent in June is expected 
to be highly variable through mid-century, as it has been in the past, 
but the models project essentially no ice in the Bering Sea in June 
during the latter half of the century.

Potential Impacts of Changes in Sea Ice on Ribbon Seals

    In association with a long[hyphen]term warming trend, there will 
likely be changes in the frequency of years with extensive ice, the 
quality of ice, and the duration of its persistence that may impact the 
amount of suitable habitat in the geographic areas that ribbon seals 
have preferred in the past. An assessment of the risks posed by these 
changes must consider the ribbon seal life[hyphen]history functions 
associated with sea ice and the potential effects on the vital rates of 
reproduction and survival. As discussed above, the sea ice regimes in 
the Bering Sea and Sea of Okhotsk will continue to be subject to large 
interannual variations in extent and seasonal duration, as they have 
been throughout recorded history. While there may be more frequent 
years in which sea ice coverage is reduced, the late[hyphen]March to 
early[hyphen]May period in which the peak of ribbon seal reproduction 
occurs will continue to have substantial ice for the foreseeable 
future. Still, there will likely be more frequent years in which the 
ice is confined to the northern regions of the observed breeding range.
    In contrast to harp seals (Pagophilus groenlandicus), which are 
their closest relatives, ribbon seals appear much less closely tied to 
traditional geographic locations for important life history functions 
such as whelping and molting. In years of low ice it is likely that 
ribbon seals will adjust, at least in part, by shifting their breeding 
locations in response to the position of the ice edge, as they have 
likely done in the past in response to interannual variability (e.g., 
Fedoseev, 1973; Braham et al., 1984; Fedoseev et al., 1988), at least 
in the Bering Sea (this may not be possible in the Sea of Okhotsk, 
where there is no northern access to higher-latitude ice-covered seas 
because the sea is bounded to the north by land). For example, 
observations indicate that extreme dispersal of ribbon seals within 
their effective range is associated with years of unusual ice 
conditions. The formation of extensive ice in the Bering Sea and Sea of 
Okhotsk has been found to result in the occurrence of large numbers of 
these seals farther south than they normally occur; the reverse is also 
true (Burns, 1981).
    There has not been, however, any study that would verify whether 
vital rates of reproduction or survival have been affected by these 
interannual variations in ice extent and breeding. Whelping, nursing of 
pups, and maturation of weaned pups could conceivably be impacted in 
years when the ice does not extend as far south as it has typically in 
the past, because the breeding areas would be farther from the 
continental shelf break, a zone that seems to be a preferred foraging 
area during spring. If these conditions occur more frequently, as is 
anticipated from projections of future climate and sea ice conditions, 
reproduction and survival of young would likely be impacted. Lacking 
relevant data, the most conservative approach is to assume that the 
population has been at equilibrium with respect to conditions in the 
past, and that a change such as more frequent breeding farther from 
preferred foraging habitats will have some impact on vital rates. Even 
given the uncertainties, we conclude that the anticipated increase in 
frequency of years with low ice extent in April and May is likely to 
have some impact on recruitment. The mechanisms for depressed 
recruitment from increased frequency of years with less ice could 
include reduced nutrition during the nursing period caused by mothers 
unable to reach preferred shelf-break foraging areas; pup mortality 
caused by more frequent failures for mothers to reunite with pups left 
on the ice during foraging trips; and mortality or reduced condition of 
maturing weaned pups caused by reduced availability of suitable ice for 
hauling out.
    As discussed above, ribbon seals have an apparent affinity for 
stable, clean, moderate[hyphen]sized ice floes that are slightly, but 
not deeply interior to the pack ice edge. Ice of this type is likely to 
occur annually in the Bering Sea and Sea of Okhotsk through the middle 
of this century, but it may more frequently be confined to smaller 
areas or areas farther north than in the past. It is more difficult to 
determine whether this type of ice will be relatively more or less 
available as the amount of ice declines as projected through the latter 
half of the century. The availability of moderately-thick, stable ice 
floes could potentially influence ribbon seal demography, particularly 
in May, via survival rates of weaned pups. Pups spend a great deal of 
time on the ice during a transition period of 2 to 3 weeks following 
weaning, presumably developing their capabilities for self-sufficient 
foraging (Burns, 1981). However, they also enter the water frequently 
during this period, and therefore may not be particularly sensitive to 
modest reductions in ice coverage or quality. Thus, although they are 
likely dependent on ice, weaned pups may not require ice floes that can

[[Page 41379]]

persist for weeks to meet their basic haul-out needs. They may, 
however, be relatively limited in their capability to respond to 
rapidly deteriorating ice fields by relocating over large distances, a 
factor that could occur more frequently in the foreseeable future.
    Subadult ribbon seals, which molt earlier than adults during March 
to mid[hyphen]May, and which are not constrained by habitat 
requirements for whelping and breeding, may be the least sensitive to 
the availability and quality of sea ice. For example, in 2007, NMFS 
research cruises in the Bering Sea encountered subadult ribbon seals in 
approximately the expected age class proportions. The obvious presence 
of seals in the subadult age class indicated that catastrophic losses 
had not occurred in the ribbon seal cohorts produced during the warm 
years of 2001-2005.
    Adult ribbon seals, which are the last to molt, might be expected 
to be the most sensitive to timing of the ice melt. Tikhomirov (1964) 
suggested that molting ribbon seals rarely enter the water and that 
stable ice is critical during this period. The pelage molt of phocid 
seals is generally thought to be facilitated or enhanced by elevated 
skin temperatures that can be achieved when hauled out versus in the 
water (Feltz and Fay, 1966). For example, it has been suggested that 
the harbor seal (Phoca vitulina, a small phocid, similar in size and 
body composition to a ribbon seal), could not complete its molt 
entirely in the water at temperatures that the species would normally 
encounter in the wild (Boily, 1995). Analysis of haul[hyphen]out 
records (section 2.6 of the status review report) indicate that 
individual adult ribbon seals haul out almost continuously for a period 
of weeks, mostly during mid[hyphen]May to late June, corresponding to 
the observed peak in molting. Sea ice coverage in June is expected to 
be low or absent more frequently in the foreseeable future. The 
implications of a loss of access to a haul[hyphen]out substrate during 
this period are unknown, but they may include energetic costs, reduced 
fertility, increased susceptibility to skin disorders and pathogens, 
and possibly increased exposure to any risks from which the hair 
normally protects a seal (e.g., abrasion from crawling over snow and 
ice). Many reports of ribbon seals out of their normal range or habitat 
have been associated with some pelage abnormalities, usually consistent 
with a disrupted or delayed molt. However, adult ribbon seals may also 
be less constrained to a specific geographic area or region of the ice 
pack once breeding is complete, around the onset of the adult molt 
(Boveng et al., 2007). They may therefore be capable of considerable 
shifts in distribution to ensure contact with suitable ice through the 
molt period, especially in the Bering Sea where there is access through 
the Bering Strait to the Chukchi Sea, where ice is expected to persist 
more frequently in June. The ultimate effect of decreased availability 
of stable platforms for adults to complete their molt out of the water 
on adult survival rate is currently difficult or impossible to model.
    The impacts discussed above on ribbon seal survival and 
reproduction in years of low ice extent, poor ice quality, or early 
melting are all of a sort that would not necessarily be significant in 
any one year; a year of low ice extent seems unlikely to cause 
widespread mortality through disruption of the adult molt, or increased 
energetic costs for pups developing their foraging capabilities. 
Rather, the overall strength of the impacts is likely a function of the 
frequency of years in which they are anticipated to occur, and the 
proportion of the population's range over which they would occur. Also, 
the effects on different age classes might be expected to be 
correlated, though not always in concert, because they involve ice 
characteristics at different times in the breeding[hyphen]molting 
period; low ice extent during breeding may not always be accompanied by 
early melting, and vice versa. As above, in the assessment of impacts 
on reproduction, we conclude that the anticipated increase in frequency 
of years with low ice extent in April, May, and June is likely to have 
an impact on survival rates.
    The extent to which ribbon seals might adapt to more frequent years 
with early ice melt by shifting the timing of reproduction and molting 
is unknown. There are many examples in the scientific literature of 
shifts in the timing of reproduction by pinnipeds and terrestrial 
mammals in response to body condition and food availability. In most of 
these cases, sub[hyphen]optimal conditions led to later reproduction, 
which would not likely be beneficial to ribbon seals as a response to 
earlier spring ice melt. Over the longer term (i.e., beyond the 
foreseeable future) a shift to an earlier mean melt date may provide 
selection pressure for an evolutionary response over many generations 
toward earlier reproduction.
    In summary, more frequent future years of reduced spring ice extent 
or ice quality could result in reduced vital rates of ribbon seal 
reproduction and survival. These potential impacts are premised on the 
assumption of a population at equilibrium with conditions in the recent 
(cooler) past and the related possibility that changes such as 
displacement of breeding locations or reduced availability of preferred 
ice types will have some energetic costs that will ultimately be 
reflected in vital rates. The age of maturation for ribbon seal females 
has been very low and pregnancy rates have been high in the recent past 
(Quakenbush and Citta, 2008), implying that foraging conditions have 
been favorable, a scenario more likely to reflect population growth 
rather than equilibrium; if so, there may be some capacity to withstand 
a reduction in vital rates without incurring an actual population 
decline. In the absence of relevant data, it is not feasible to 
estimate quantitatively the magnitude of the anticipated impacts. The 
significance of demographic risks to the persistence of ribbon seals 
within the foreseeable future is assessed qualitatively below (see 
Demographic Risks Assessment).
    The threats associated with decreases in sea ice habitat that were 
judged by the BRT to be of high significance include reductions in sea 
ice habitat suitable for molting in both the Bering Sea and the Sea of 
Okhotsk; and reductions in sea ice habitat suitable for whelping and 
nursing, pup maturation, and mating in the Sea of Okhotsk. Reductions 
in sea ice habitat suitable for whelping and nursing, pup maturation, 
and mating in the Bering Sea were judged by the BRT to be of moderate 
significance. We concur with the BRT's assessment.

Impacts on Ribbon Seals Related to Changes in Ocean Conditions

    Ocean acidification is an ongoing process whereby chemical 
reactions occur that lower seawater pH and carbonate saturation due to 
CO2 absorption by the ocean. Ocean acidification is likely 
to affect the ecosystem structure in the ribbon seals' habitats in the 
foreseeable future. The exact nature of these impacts cannot be 
predicted, and some likely will amplify more than others. As discussed 
above, ribbon seals eat a variety of fishes, squids, octopuses, and 
crustaceans. In addition to interfering with calcification of organisms 
at lower trophic levels, changes in ocean chemistry can have direct 
effects on the physiology of marine invertebrates and fish. Among 
invertebrates, squid are expected to be particularly sensitive to 
increases in CO2. These ecosystem responses may have very 
long lags as they propagate through trophic webs.
    Although the ribbon seal's varied diet would appear to confer some 
resilience

[[Page 41380]]

to shifts in prey availability, major disruptions in the amount of 
productivity reaching pelagic, upper trophic species would be expected 
to have demographic impacts. Survival of juvenile ribbon seals would be 
expected to be the most sensitive, as their diet is narrower and more 
skewed toward invertebrates. Sufficiently large ecosystem shifts that 
persist more than a few years could also impact adult survival and 
reproductive rates. The range of potential ecological scenarios, 
however, is extremely complex and may even include some that could be 
ameliorative or beneficial to ribbon seals. The vast preponderance of 
ocean acidification impacts that have been identified, however, seem 
negative for ribbon seal prey. In the absence of compelling evidence 
for specific positive effects, the net effect of ocean acidification on 
ribbon seals is expected to be negative. The threat posed to ribbon 
seals from decreases in prey density and/or availability due to ocean 
acidification was judged by the BRT to be of moderate significance in 
both the Bering Sea and Sea of Okhotsk, and we agree with this 
assessment.
    Changes in ribbon seal prey, anticipated in response to habitat 
changes resulting from ocean warming and loss of sea ice, have the 
potential for negative impacts, but these impacts are not well 
understood. Some changes already documented in the Bering Sea and the 
North Atlantic Ocean are of a nature that could be ameliorative or 
beneficial to ribbon seals. For example, warming and decrease in ice 
extent could increase pelagic productivity in favor of pelagic foraging 
by ribbon seals. Such ecosystem responses may have very long lags as 
they propagate through trophic webs. The apparent flexibility in ribbon 
seal foraging locations and habits may make the threats posed from 
changes in prey due to ocean warming and loss of ice of lower concern 
than more direct impacts from changes in sea ice. The BRT judged the 
threats posed to ribbon seals from decreases in prey density and/or 
availability due to changes in ice cover and ocean warming to be of 
moderate significance in both the Bering Sea and the Sea of Okhotsk, 
and we agree with this assessment.

Summary of Factor A

    The BRT judged the threats to ribbon seal persistence from 
destruction or modification of habitat to be of greater significance 
than the threats posed from all other factors. Overall, the BRT judged 
the threats posed under Factor A to be of high significance in the 
Bering Sea and of very high significance in the Sea of Okhotsk. The BRT 
concluded that although it is impossible to project the trajectory of 
ribbon seal abundance with any certainty, it is likely that the 
combined effects of diminished sea ice habitat and disrupted prey 
communities will reduce ribbon seals' vital rates of survival and 
reproduction gradually throughout the foreseeable future. We agree with 
the BRT's findings. However, as discussed below, our analysis did not 
indicate these anticipated impacts on ribbon seal vital rates render 
the species likely to become an endangered species within the 
foreseeable future (threatened). Relevant considerations supporting 
this conclusion include: (1) There is evidence from some recent years 
with unusual ice conditions that ribbon seals may compensate for 
changes in sea ice, as least in part, by moving to areas with better 
ice, at least in the Bering Sea; (2) ribbon seals are known to have a 
diet that is ecologically and trophically diverse and they are able to 
forage over a wide range of ocean depths, which should enhance 
resilience to climate-related changes in prey communities; and (3) 
individual ribbon seals have the capability to undertake large seasonal 
movements and shifts between pelagic and pack ice habitats, which may 
mitigate some anticipated impacts of anthropogenic climate change. The 
demographic risks to the persistence of ribbon seals within the 
foreseeable future are considered further below (see Demographic Risks 
Assessment).

B. Overutilization for Commercial, Subsistence, Recreational, 
Scientific, or Educational Purposes

    While commercial hunting for ribbon seals is not allowed in the 
United States, such harvests are permitted by the Russian Federation. 
Commercial harvests by Russian sealers have at times been high enough 
to cause significant reductions in abundance and catch-
per[hyphen]unit[hyphen]effort. The population apparently rebounded from 
a period of high harvest in the 1960s. Substantial but lower numbers 
were harvested for a few years in the early 1990s. Although Russian 
government quotas were recently put in place that would allow large 
harvests (~18,000 annually), the actual takes are low because of poor 
economic viability. There is some effort in Russia to develop new uses 
and markets for seal products, but unless this effort is successful, 
the harvest is unlikely to increase in the near future. The numbers of 
ribbon seals harvested for subsistence use by indigenous hunters in 
Russia and Alaska are considered insignificant by most researchers, 
primarily due to the difficulty of accessing the seals in far offshore 
ice. Subsistence harvest levels have been low historically in Russia, 
and the current subsistence harvest is not thought to be a threat to 
ribbon seals there. Although estimates of subsistence harvest in Alaska 
are varied, all are low and sustainable relative to the population 
size. Subsistence harvest levels could potentially increase in the 
future if ribbon seals are forced to use a reduced and more northerly 
ice field, which could put them in closer proximity to Alaska Native 
communities near the Bering Strait. Changes in subsistence or 
commercial takes cannot be predicted with any certainty at this time. 
Scientific and educational utilization of ribbon seals is currently at 
very low levels and is not projected to increase to significant threat 
levels in the foreseeable future. Overall, the significance of the 
threats posed to ribbon seal persistence from overutilization were 
judged by the BRT to be low in both the Bering Sea and the Sea of 
Okhotsk, and we concur with this finding.

C. Diseases, Parasites, and Predation

    A variety of pathogens (or antibodies), diseases, helminthes, 
cestodes, and nematodes have been found in ribbon seals. The prevalence 
of these agents is not unusual among seals, but the population impact 
is unknown. Beginning in July and August 2011, higher than normal 
numbers of sick and dead ringed seals along the coast of the North 
Slope of Alaska led to the declaration of an unusual mortality event 
(UME). Most pinnipeds with UME symptoms were ringed seals from the 
North Slope, but sick walruses (Odobenus rosmarus), spotted seals, and 
bearded seals were also found on the North Slope and in the Bering 
Strait region. Only one ribbon seal, a yearling, was reported with UME 
symptoms. The cause of the UME is still unknown, but additional 
bacterial and fungal testing and advanced molecular screening for 
unknown viruses are being conducted in a continuing effort to determine 
an explanation. There are a couple possibilities that may explain why 
only one sick ribbon seal was found during this UME. Ribbon seals are 
primarily pelagic and solitary during the summer and fall months when 
most of the UME seals were found. Thus, they might not have become sick 
in the same numbers as other ice seals because disease transmission 
among individuals may be limited due to their solitary lifestyle. 
However, it is also possible that many ribbon seals did become sick 
during the UME, but because they are pelagic they may have died out at 
sea and not stranded in areas where they could be

[[Page 41381]]

counted. There may be an increased risk of outbreaks of novel pathogens 
or parasites as climate[hyphen]related shifts in species distributions 
lead to new modes of transmission. For both the Bering Sea and the Sea 
of Okhotsk, the BRT judged the potential threats to ribbon seals from 
increased infection or disease to be of moderate significance, and from 
an increase in parasites to be of low significance, and we agree with 
these findings.
    There is little or no direct evidence of significant predation on 
ribbon seals, and they are not thought to be a primary prey of any 
predators. Polar bears (Ursus maritimus) and killer whales (Orcinus 
orca) may be the most likely opportunistic predators in the current sea 
ice regime, but walruses and sharks could pose a potentially greater 
risk if reduced sea ice conditions force these species into closer 
proximity in the future. The BRT judged the significance of the threat 
posed to ribbon seals from increased predation associated with changes 
in sea ice cover to be low in both the Bering Sea and the Sea of 
Okhotsk, and we agree with this assessment.

D. Inadequacy of Existing Regulatory Mechanisms

    As noted above in the discussion of Factor A, a primary concern 
about the conservation status of the ribbon seal stems from the 
likelihood that its sea ice habitat has been modified by the warming 
climate and, more so, that the scientific consensus projections are for 
continued and perhaps accelerated warming in the foreseeable future 
combined with modification of habitat by ocean acidification and 
warming water temperatures. Current mechanisms do not effectively 
regulate GHG emissions, which are contributing to global climate change 
and associated modifications to ribbon seal habitat. The projections we 
used to assess risks from GHG emissions were based on the assumption 
that no new regulation will take place (the underlying IPCC emissions 
scenarios were all ``non-mitigated'' scenarios). Therefore, the 
inadequacy of mechanisms to regulate GHG emissions is already included 
in our risk assessment, and contributes to the risks posed to ribbon 
seals by these emissions.
    We also note that regulations which govern commercial harvest of 
ice seals in Russia are over 20 years old and we do not have good 
information regarding whether regulatory mechanisms are in place to 
ensure that potential commercial harvests in Russian waters are 
conducted in a sustainable fashion. As noted above, currently there is 
some effort in Russia to develop new uses and markets for seal 
products, but unless this effort is successful, the harvest is unlikely 
to increase in the near future. The BRT considered the threat posed to 
ribbon seal persistence by commercial harvest to be low in both the 
Bering Sea and the Sea of Okhotsk. We conclude that the data currently 
available do not suggest that inadequacy of mechanisms to regulate 
commercial harvest poses a significant threat to ribbon seals.

E. Other Natural or Manmade Factors Affecting the Species' Continued 
Existence

    Although some pollutants are elevated in ribbon seals, there is no 
conspicuous evidence of toxicity or other significant impacts to the 
species. Continued and expanded monitoring would be prudent to document 
any trends in the contaminants of greatest concern.
    Oil and gas exploration and development activities may include 
drilling operations, pipeline construction and operation, seismic 
surveys, and vessel and aircraft operations. The main issues for 
evaluating the impacts of exploration and development activities on 
ribbon seals are the effects of noise, physical disturbance, and 
potential oil spills produced from these activities. Any negative 
effects on ribbon seals from noise and disturbance associated with 
development activities are likely to be minor and localized. Ribbon 
seals are also highly dispersed during the summer open[hyphen]water 
season, so the rate of interactions with seismic surveys would likely 
be low, and, in any case, seals have not been shown to be significantly 
impacted by oil and gas seismic surveys. The threat posed to ribbon 
seals by oil spills will increase if offshore oil and gas development 
and shipping activities increase across their range as predicted. The 
potential impacts would be greatest during April-June when the seals 
are relatively aggregated, and substantially lower during the remainder 
of the year when they are dispersed in the open water throughout the 
North Pacific Ocean, Sea of Okhotsk, and Bering and Chukchi seas.
    Estimates from observed bycatch in commercial fisheries indicate 
that less than 200 ribbon seals per year are taken, though mortalities 
may be under[hyphen]reported in some fisheries. This level of estimated 
bycatch of ribbon seals represents less than 0.1 percent of their 
estimated population. Because there is little or no fishery activity 
near the widely distributed low densities of ribbon seals when they are 
associated with ice, and they are highly dispersed during the remainder 
of the year, bycatch is unlikely to be a significant threat to ribbon 
seal populations. For the same reason, competition from fisheries that 
reduce local abundance of ribbon seal prey is unlikely to be a 
significant threat to ribbon seal populations. Broad[hyphen]scale 
reduction in a commercially[hyphen]fished, primary prey species could 
have a significant impact, but the large groundfish fisheries in 
Alaskan waters are managed to prevent depletion of the stocks; none of 
those fisheries is in an overfished status.
    The extraordinary reduction in Arctic sea ice that has occurred in 
recent years has renewed interest in trans[hyphen]Arctic navigation 
routes connecting the Atlantic and Pacific Oceans via the Northwest 
Passage and the Northern Sea Route. Climate models predict that the 
warming trend in the Arctic will accelerate, causing the ice to melt 
earlier in the spring and resume freezing later in the fall, resulting 
in an expansion of potential shipping routes and lengthening the 
potential navigation season. Though few details are available regarding 
actual shipping levels in the Sea of Okhotsk, resource development over 
the last decade stands out as a likely significant contributor. It is 
clear that considerable ship traffic is needed to support present oil 
and gas operations, primarily off the northeastern coast of Sakhalin 
Island and the western coast of the Kamchatka Peninsula, with future 
developments pointing to an ever-growing shipping industry to support 
the area's energy and minerals commerce. Large-scale commercial 
fishing, which occurs in many parts of the Sea of Okhotsk, also 
contributes to ship traffic there.
    The most significant risk posed by shipping activities to ribbon 
seals is the accidental or illegal discharge of oil or other toxic 
substances carried by ships due to their immediate and potentially 
long-term effects on individual animals, populations, food webs, and 
the environment. Shipping activities can also affect ribbon seals 
directly through noise and physical disturbance (e.g., icebreaking 
vessels), as well as indirectly through ship emissions and possible 
effects of introduction of invasive species.
    Current and future shipping activities in the Arctic pose varying 
levels of threat to ribbon seals depending on the type and intensity of 
the shipping activity and its degree of spatial and temporal overlap 
with the seals. These factors are inherently difficult to know or 
predict, making threat assessment uncertain. Ribbon seals are typically 
reported to be widely distributed in low

[[Page 41382]]

densities on sea ice during the spring reproductive season, are likely 
even more dispersed during the summer and fall open-water seasons, and 
are not known to congregate in large numbers. Their highly dispersed 
distribution may help mitigate the risks of localized shipping threats, 
such as oil spills or physical disturbance, since the impacts from such 
events would be less likely to affect large numbers of seals. The fact 
that nearly all shipping activity in the Arctic purposefully avoids 
areas of ice and primarily occurs during the ice-free or low-ice 
seasons may also help mitigate the threats of shipping to ribbon seals 
since this species is closely associated with ice during the whelping, 
nursing, and molting periods when the seals (especially young pups) may 
be most vulnerable to shipping impacts. Icebreakers may pose special 
risks to ribbon seals since they are capable of operating year-round in 
all but the heaviest ice conditions and are sometimes used to escort 
other types of vessels (e.g., tankers and bulk carriers) through ice-
covered areas. If icebreaking activities increase in the Arctic in the 
future as expected, the likelihood of negative impacts (e.g., oil 
spills, pollution, noise, and disturbance) occurring in ice-covered 
areas where ribbon seals reside will likely also increase. Shipping 
impacts alone may comprise a low risk to entire populations, but when 
combined with the effects related to diminishing ice cover, such as 
increasingly denser aggregations, the impacts may be magnified and may 
play an important role in affecting the future health of populations.
    Overall, the BRT judged the threats posed to ribbon seals from 
other natural or man-made factors to be of moderate significance in 
both the Bering Sea and the Sea of Okhotsk. We agree with the BRT's 
finding.

Demographic Risks Assessment

    Threats to a species' long-term persistence are manifested 
demographically as risks to its abundance; productivity; spatial 
structure and connectivity; and genetic and ecological diversity. These 
viability criteria, outlined in McElhany et al. (2000), reflect 
concepts that are well-founded in conservation biology and that 
individually and collectively provide the most direct indices or 
proxies of extinction risk. A species at very low levels of abundance 
and with few populations will be less tolerant to environmental 
variation, catastrophic events, genetic processes, demographic 
stochasticity (variability in population growth rates arising from 
random differences among individuals in survival and reproduction), 
ecological interactions, and other processes. A rate of productivity 
that is unstable or declining over a long period of time can indicate 
poor resiliency to future environmental change. A species that is not 
widely distributed across a variety of well-connected habitats is at 
increased risk of extinction due to environmental perturbations, 
including catastrophic events. A species that has lost locally adapted 
genetic and ecological diversity may lack the raw resources necessary 
to exploit a wide array of environments and endure short- and long-term 
environmental changes.
    The BRT members' assessments of the significance of demographic 
risks to the persistence of ribbon seals were summarized qualitatively 
using a numerical scoring system. This scoring system, which was 
modeled on similar approaches used in other ESA status reviews (e.g., 
Atlantic Wolffish BRT, 2009; Butler et al., 2009; Cameron et al., 2010; 
Kelly et al., 2010), was designed to elicit expert judgment about the 
likelihood that the known and potential threats will impact the 
species' persistence. Specifically, each BRT member considered the risk 
that the population may be placed in danger of extinction by 
demographic problems with abundance, productivity, spatial structure, 
or diversity, within the next 50 years and the next 100 years, and then 
assigned a score to each of these demographic risk categories using the 
following values: 1--very low or zero risk, 2--low risk, 3--medium 
risk, 4--high risk, and 5--very high risk. The average score and the 
range of scores were tabulated for each of the four demographic risk 
categories.
    The BRT judged the demographic risks to the persistence of the 
ribbon seal between now and 2050 to be very low (abundance, 
productivity, and diversity) to low (spatial structure); and between 
now and 2100 to be low (abundance, productivity, and diversity) to 
medium (spatial structure). The medium risk score for demographic 
problems associated with spatial structure primarily reflects the 
anticipated direct impacts to ribbon seals stemming from loss of 
habitat patches and connectivity. We concur with the BRTs findings.
    To supplement the demographic risks assessment and express a 
single, summarized judgment about extinction risk, each BRT member also 
allocated 10 likelihood points among five time interval categories (now 
to 2025, 2026 to 2050, 2051 to 2075, 2076 to 2100, and beyond 2100) to 
indicate his or her judgment about the time until ribbon seals would 
reach a population level of 5,000 individuals, representing a 
hypothetical minimum viable population (MVP). Degree of uncertainty in 
this judgment is expressed by spreading the points across the time 
interval categories. In other words, if a member believed that ribbon 
seals will never decline to 5,000 individuals, or at least not for a 
very long time, all 10 likelihood points would be allocated to the 
interval ``beyond 2100.'' Or, if the member believed strongly that 
ribbon seals will reach that level in the latter half of this century, 
and it is equally likely to happen in either the time interval ``2051 
to 2075'' or ``2076 to 2100,'' five likelihood points would be 
allocated to each of those two categories. Thus, this assignment of 
likelihood points represents the opinion of BRT members as to whether 
the population may decline below the hypothetical MVP in the specified 
time intervals based on reasoned expert judgment. The level of 5,000 
individuals was selected without regard to specific aspects of ribbon 
seal life history that would determine the species' MVP size (which are 
largely unknown). Rather, it was chosen as a value that has been 
asserted to be useful because of its derivation as the approximate 
median from a meta-analysis of MVPs for many species (Traill et al., 
2007; Traill et al., 2010). We note, however, that some have cautioned 
about placing confidence in this value (Flather et al., 2011). The BRT 
members assigned all likelihood points to the three time intervals 
beyond 2050. Among the eleven BRT members, 0 percent of the likelihood 
points was ascribed to the combined intervals from now to 2050, four 
percent was ascribed to the interval 2051 to 2075, 13 percent was 
ascribed to 2076 to 2100, and 83 percent was ascribed to the period 
beyond 2100. In other words, the BRT's collective distribution of 
points among time intervals indicating when the ribbon seal population 
may decline to a hypothetical MVP was concentrated in the time interval 
beyond the end of the current century. The range among BRT members in 
the percentage of likelihood points assigned to the combined time 
interval categories from now to 2100 was 0 percent (five BRT members) 
to 50 percent (i.e., 5 points; one BRT member), reflecting the 
variation in this judgment that results from sparse and uncertain 
information underlying this assessment (the 5 other BRT members 
assigned from 1 to 4 points). The BRT's scoring was of course 
subjective, but it offers an indication of the BRT members' 
professional judgment that

[[Page 41383]]

there is a low near-term extinction risk. We compared the scoring here 
with the BRT's demographic risk assessment and our evaluation of the 
ESA section 4(a)(1) factors above and found them consistent.

Conservation Efforts

    When considering the listing of a species, section 4(b)(1)(A) of 
the ESA requires consideration of efforts by any state, foreign nation, 
or political subdivision of a state or foreign nation to protect the 
species. Such efforts would include measures by Native American tribes 
and organizations, local governments, and private organizations. Also, 
Federal, tribal, state, and foreign recovery actions (16 U.S.C. 
1533(f)), and Federal consultation requirements (16 U.S.C. 1536) 
constitute conservation measures. In addition to identifying these 
efforts, under the ESA and our Policy on the Evaluation of Conservation 
Efforts (PECE; 68 FR 15100; March 28, 2003), we must evaluate the 
certainty of implementing the conservation efforts and the certainty 
that the conservation efforts will be effective on the basis of whether 
the effort or plan establishes specific conservation objectives, 
identifies the necessary steps to reduce threats or factors for 
decline, includes quantifiable performance measures for monitoring 
compliance and effectiveness, incorporates the principles of adaptive 
management, and is likely to improve the species' viability at the time 
of the listing determination.
    At this time, we are not aware of any formalized conservation 
efforts for ribbon seals that have yet to be implemented, or which have 
recently been implemented, but have yet to show their effectiveness in 
removing threats to the species. Therefore, we do not need to evaluate 
any domestic conservation efforts under the PECE.
    NMFS has an agreement with the Ice Seal Committee (ISC) under 
section 119 of the Marine Mammal Protection Act to conserve and provide 
co-management of subsistence use of ice seals by Alaska Natives. The 
ISC co-manages ice seals with NMFS by monitoring subsistence harvest 
and cooperating on needed research and education programs pertaining to 
ice seals. NMFS's National Marine Mammal Laboratory is engaged in an 
active research program for ribbon seals. The new information from 
research will be used to enhance our understanding of the risk factors 
affecting ribbon seals, thereby improving our ability to develop 
effective management measures for the species.
    ESA section 4(b)(1)(B) requires us to give consideration to species 
which have been designated as requiring protection from unrestricted 
commerce by any foreign nation, or pursuant to any international 
agreement; or identified as in danger of extinction, or likely to 
become so within the foreseeable future, by any state agency or any 
agency of a foreign nation that is responsible for the conservation of 
the species. We are not aware of any such special protections or 
designations, or of any conservation efforts undertaken by foreign 
nations specifically to protect ribbon seals. Ribbon seals are not 
afforded any protective measures or special status via the Convention 
for the International Trade in Endangered Species or the International 
Union for Conservation of Nature.

Listing Determination

    We have reviewed the status of the ribbon seal, fully considering 
the best scientific and commercial data available, including the status 
review report. We have reviewed the threats to the ribbon seal, as well 
as other relevant factors, and given consideration to conservation 
efforts and special designations for ribbon seals by states and foreign 
nations. The best available information indicates that the threats 
posed to the persistence of the ribbon seal from foreseeable future 
destruction or modification of habitat attributable to climate change 
are of greater significance than threats from other factors. Although 
the trajectory of ribbon seal abundance is impossible to project with 
certainty, it is likely that the effects of diminished sea ice habitat 
and disrupted prey communities will reduce ribbon seal's vital rates of 
reproduction and survival gradually throughout the foreseeable future. 
However, our analysis did not indicate that the ribbon seal is in 
danger of extinction (endangered) or that the anticipated impacts on 
ribbon seal vital rates render the species likely to become an 
endangered species within the foreseeable future (threatened) 
throughout its range. Relevant considerations supporting this 
conclusion include: (1) There is evidence from some recent years with 
unusual ice conditions that ribbon seals may compensate for changes in 
sea ice, as least in part, by moving to areas with better ice, at least 
in the Bering Sea; (2) ribbon seals are known to have a diet that is 
ecologically and trophically diverse and they are able to forage over a 
wide range of ocean depths, which should enhance resilience to climate-
related changes in prey communities; (3) ribbon seals tend to be highly 
dispersed and mostly solitary during the ice-free season, which would 
provide a hedge against localized threats such as oil spills, 
concentrations of fishery activity, and interactions with shipping; and 
(4) individual ribbon seals have the capability to undertake large 
seasonal movements and shifts between pelagic and pack ice habitats, 
which may mitigate some anticipated impacts of anthropogenic climate 
change. We therefore find that the ribbon seal does not warrant listing 
as threatened or endangered throughout its range at this time.

Significant Portion of the Range Evaluation

    Under the ESA and our implementing regulations, a species warrants 
listing if it is threatened or endangered throughout all or a 
significant portion of its range. In our analysis for this listing 
determination, we initially evaluated the status of and threats to the 
ribbon seal throughout its entire range. We found that the consequences 
of habitat change associated with a warming climate can be expected to 
manifest throughout the current breeding and molting ranges of ribbon 
seals, and that the ongoing and projected changes in sea ice habitat 
are likely to reduce the ribbon seal's vital rates of reproduction and 
survival gradually through the foreseeable future. However, despite the 
expectation of a gradual decline, we concluded that the ribbon seal is 
not endangered nor is it likely to become so within the foreseeable 
future throughout its range.
    The magnitude of the threats posed to the persistence of ribbon 
seals, including from changes in sea ice habitat, is likely to vary to 
some degree across the range of the species depending on a number of 
factors, including where affected populations occur. In light of the 
potential differences in the magnitude of the threats to specific areas 
or populations, we next evaluated whether the ribbon seal might be 
threatened or endangered in any significant portion of its range. In 
accordance with our draft policy on ``significant portion of its 
range,'' our first step in this evaluation was to review the entire 
supporting record for this listing determination to ``identify any 
portions of the range[s] of the [DPSs] that warrant further 
consideration'' (76 FR 77002; December 9, 2011). We evaluated whether 
substantial information indicated ``that (i) the portions may be 
significant [within the meaning of the draft policy] and (ii) the 
species [occupying those portions] may be in danger of extinction or 
likely to become so within the

[[Page 41384]]

foreseeable future'' (76 FR 77002; December 9, 2011). Depending on the 
biology of a species, its range, and the threats it faces, it might be 
more efficient for us to address the significance question first or the 
status question first. Thus, if we determine that a portion of the 
range is not ``significant,'' we do not need to determine whether the 
species occupying that portion is threatened or endangered there; if we 
determine that the members of a species occupying a portion of its 
range are not threatened or endangered, we do not need to determine if 
that portion is ``significant.'' In practice, a key part of the 
determination as to whether a species is in danger of extinction in a 
significant portion of its range is whether the threats are 
geographically concentrated in some way. If the threats to the species 
are essentially uniform throughout its range, no portion is likely to 
warrant further consideration. Moreover, if any concentration of 
threats to the species occurs only in portions of the species' range 
that clearly would not meet the biologically based definition of 
``significant,'' such portions will not warrant further consideration. 
Finally, if threats, even though acting only in a portion of the range 
of the species, would cause the entire species to be threatened or 
endangered, the conclusion would be that the species is threatened or 
endangered throughout its range (rather than only in a significant 
portion of its range).
    All of the ESA threat factors assigned scores by the BRT (Factors 
A, B, C, and E) were judged to be of relatively higher significance in 
the Sea of Okhotsk than in the Bering Sea, and we concur with this 
assessment. Therefore, we evaluated whether there is substantial 
information suggesting that the hypothetical loss of the portion of the 
species residing in the Sea of Okhotsk would reasonably be expected to 
increase the demographic risks to the point that the species would then 
be in danger of extinction, i.e., whether the Sea of Okhotsk portion of 
the species' range should be considered ``significant.'' At present, 
the numbers of ribbon seals in both the Bering Sea and Sea of Okhotsk 
portions of the range are on the order of 100,000 or more in each sea 
basin. As discussed in more detail in the status review report, 
populations or sub-populations of this magnitude and with the life 
history characteristics of the ribbon seal are typically immune to 
demographic risks that are associated with or exacerbated by low 
abundance, such as year-to-year environmental fluctuations, loss of 
diversity, failure of breeding systems, and lack of potential for 
productivity. The climate related threats facing ribbon seals are 
expected to increase more or less in parallel between the Bering Sea 
and Sea of Okhotsk, albeit more quickly in the latter. If ribbon seal 
numbers in the Bering Sea decrease in the future to levels at which the 
demographic risks discussed above become significant, then the loss of 
either the Sea of Okhotsk or the Bering Sea portions would likely place 
the entire species in danger of extinction. However, at least in the 
near term, the BRT concluded, and we agree, that the loss of the Sea of 
Okhotsk portion of the ribbon seal population would not place the 
remainder, the Bering Sea portion, in danger of extinction (Boveng et 
al., 2013, section 4.3.3.3). Because the portion of the ribbon seal 
population residing in the Sea of Okhotsk is not so significant that 
its hypothetical loss would render the species endangered, we conclude 
that the Sea of Okhotsk portion does not constitute a significant 
portion of the ribbon seal's range. Consequently, we need not address 
the question of whether the portion of the species occupying the Sea of 
Okhotsk is threatened or endangered.

Conclusion

    Our review of the information pertaining to the five ESA section 
4(a)(1) factors does not support the assertion that there are threats 
acting on the species or its habitat that have rendered the ribbon seal 
to be in danger of extinction or likely to become so in the foreseeable 
future, throughout all or a significant portion of its range. 
Therefore, listing the ribbon seal as threatened or endangered under 
the ESA is not warranted at this time.
    We will continue to monitor the status of the ribbon seal. If 
conditions change in the future, we will re-evaluate the status of this 
species to determine whether it should be listed as threatened or 
endangered under the ESA. Because of the remaining uncertainties 
regarding the effects of climate change, sea ice cover, and potential 
Russian harvests, following the 2008 status review of the ribbon seal, 
this species was added to our Species of Concern list (https://www.nmfs.noaa.gov/pr/species/concern/). The Species of Concern list 
serves to: (1) Increase public awareness about the species; (2) further 
identify data deficiencies and uncertainties in the species' status and 
the threats it faces; and (3) stimulate cooperative research efforts to 
obtain the information necessary to evaluate the species' status and 
threats. As resources permit, we will conduct further studies of ribbon 
seal abundance and status. We will evaluate results of these and any 
other studies that may be conducted and undertake a new status review, 
if warranted.

References Cited

    A complete list of all references cited in this rulemaking can be 
found on our Web site at https://alaskafisheries.noaa.gov and is 
available upon request from the NMFS office in Juneau, Alaska (see 
ADDRESSES).

Authority

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

    Dated: July 3, 2013.
Alan D. Risenhoover,
Director, Office of Sustainable Fisheries, performing the functions and 
duties of the Deputy Assistant Administrator for Regulatory Programs.
[FR Doc. 2013-16601 Filed 7-9-13; 8:45 am]
BILLING CODE 3510-22-P