Federal Register, Volume 80 Issue 118 (Friday, June 19, 2015)

[Federal Register Volume 80, Number 118 (Friday, June 19, 2015)]
[Notices]
[Pages 35306-35317]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-15087]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[Docket No. 150106016-5016-01]
RIN 0648-XD703

Endangered and Threatened Wildlife and Plants; Notice of 12-Month
Finding on a Petition To List Bottlenose Dolphins in Fiordland, New
Zealand as Threatened or Endangered Under the Endangered Species Act

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

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, NMFS, announce a 12-month finding on a petition to list
bottlenose dolphins (Tursiops truncatus) within Fiordland, New Zealand
as threatened or endangered under the Endangered Species Act (ESA).
Based on our review of the best scientific and commercial data
available, we have determined that the bottlenose dolphins within
Fiordland do not meet the criteria for identification as a distinct
population segment. Therefore, these dolphins do not warrant listing,
and we do not propose to list these dolphins under the ESA.

DATES: This finding was made on June 19, 2015.

ADDRESSES: Information used to make this finding is available for
public inspection by appointment during normal business hours at NMFS,
Office of Protected Resources, 1315 East West Highway, Silver Spring,
MD 20910. The petition and the list of the references used in making
this finding are also available on the NMFS Web site at http://www.nmfs.noaa.gov/pr/species/petition81.htm.

FOR FURTHER INFORMATION CONTACT: Lisa Manning, NMFS, Office of
Protected Resources (OPR), (301) 427-8403.

SUPPLEMENTARY INFORMATION:

Background

On July 15, 2013, we received a petition from WildEarth Guardians
to list 81 marine species as threatened or endangered under the
Endangered Species Act (ESA). We found that the petitioned actions may
be warranted for 27 of the 81 species and announced the initiation of
status reviews for each of the 27 species (78 FR 63941, October 25,
2013; 78 FR 66675, November 6, 2013; 78 FR 69376, November 19, 2013; 79
FR 9880, February 21, 2014; and 79 FR 10104, February 24, 2014). Among
the 27 species that we determined may warrant listing under the ESA is
the bottlenose dolphin, Tursiops truncatus, of Fiordland, New Zealand.
This finding addresses those bottlenose dolphins.
We are responsible for determining whether species are threatened
or endangered under the ESA (16 U.S.C. 1531 et seq.). To make this
determination, we consider first whether a group of organisms
constitutes a ``species'' under the ESA, then whether the status of the
species qualifies it for listing as either threatened or endangered.
Section 3 of

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the ESA defines a ``species'' to include ``any subspecies of fish or
wildlife or plants, and any distinct population segment of any species
of vertebrate fish or wildlife which interbreeds when mature.'' On
February 7, 1996, NMFS and the U.S. Fish and Wildlife Service (USFWS;
together, the Services) adopted a policy describing what constitutes a
distinct population segment (DPS) of a taxonomic species (the DPS
Policy, 61 FR 4722). The DPS Policy identifies two elements that must
be considered when identifying a DPS: (1) The discreteness of the
population segment in relation to the remainder of the species (or
subspecies) to which it belongs; and (2) the significance of the
population segment to the remainder of the species (or subspecies) to
which it belongs. As stated in the DPS Policy, Congress expressed its
expectation that the Services would exercise authority with regard to
DPSs sparingly and only when the biological evidence indicates such
action is warranted.
Section 3 of the ESA defines an endangered species as ``any species
which is in danger of extinction throughout all or a significant
portion of its range'' and a threatened species as one ``which is
likely to become an endangered species within the foreseeable future
throughout all or a significant portion of its range.'' We interpret an
``endangered species'' to be one that is presently in danger of
extinction. A ``threatened species,'' on the other hand, is not
presently in danger of extinction, but is likely to become so in the
foreseeable future (that is, at a later time). In other words, the
primary statutory difference between a threatened and endangered
species is the timing of when a species may be in danger of extinction,
either presently (endangered) or in the foreseeable future
(threatened).
Section 4(a)(1) of the ESA requires us to determine whether any
species is endangered or threatened due to any one or a combination of
the following five threat factors: The present or threatened
destruction, modification, or curtailment of its habitat or range;
overutilization for commercial, recreational, scientific, or
educational purposes; disease or predation; the inadequacy of existing
regulatory mechanisms; or other natural or manmade factors affecting
its continued existence. We are also required to make listing
determinations based solely on the best scientific and commercial data
available, after conducting a review of the species' status and after
taking into account efforts being made by any state or foreign nation
to protect the species.

Species Description

Taxonomy and Physical Characteristics

The common bottlenose dolphin, Tursiops truncatus, is one of the
most well-known and well-studied species of marine mammals. The
bottlenose dolphin is a cetacean within suborder Odontoceti (toothed
whales) and family Delphinidae. Up to 20 separate species have been
proposed at various times as a consequence of bottlenose dolphins'
geographically diverse and highly plastic physical characteristics.
Although uncertainty and debate remain regarding their taxonomic
status, two species of Tursiops are now generally recognized--the
common bottlenose, Tursiops truncatus, and the Indo-Pacific bottlenose,
T. aduncus (Connor et al. 2000). A third species, T. australis, which
occurs along the southern coast of Australia, has been recently
proposed (Viaud-Martinez et al. 2008) but is not yet formally accepted.
The bottlenose dolphins in Fiordland, New Zealand have been placed in
T. truncatus based on their longer length; smaller beaks, flippers, and
dorsal fins; and lack of ventral spotting, which is common in T.
aduncus and very rarely seen on T. truncatus (Wang et al., 2000;
Boisseau, 2003). This classification has since been supported by
genetic data (Tezanos-Pinto et al. 2008).
In general, the bottlenose dolphin body form is described as being
robust with a short, thick beak. Their coloration ranges from light
gray to black with lighter coloration on the belly. Coastal animals are
typically smaller and lighter in color, while pelagic animals tend to
be larger, and darker in coloration. Dolphins living in warm, shallow
waters also tend to have smaller body sizes and proportionately larger
flippers than animals living in cool, deep waters (Hersh and Duffield
1990; Chong and Schneider 2001).
Bottlenose adults range in length from about 1.8 to 3.9 m, with
some even larger sizes reported for some populations from the southern
hemisphere (Leatherwood et al., 1983). Based on measurements of two
carcasses and stereophotogrammetry (a technique for obtaining
measurements from photographs) of live dolphins from one fiord
(Doubtful Sound), the bottlenose dolphins in Fiordland appear to be
morphologically similar to pelagic animals and those in temperate
coastal regions, but larger and more robust in body form than
bottlenose dolphins in lower latitudes (Chong and Schneider 2001;
Boisseau 2003). The two carcasses measured were of an adult, 7-year old
male that was 3.2 m long and a sub-adult 3-year old female that was 2.8
m long (Boisseau, 2003). Asymptotic total length in adult bottlenose
dolphins in Doubtful Sound is predicted to reach at least 3.2 m (Chong
and Schneider 2001). Sexual dimorphism of Fiordland bottlenose dolphins
may also occur, with males potentially reaching larger sizes than
females (Boisseau, 2003). Based on laser photogrammetry (also known as
laser-metrics) on 20 adult females and 14 adult males, Rowe and Dawson
(2008) found that adult males in Doubtful Sound have significantly
taller and wider dorsal fins than adult females; however, the
differences were not such that adults could be sexed in the wild on the
basis of their dorsal fins.

Range and Distribution

Bottlenose dolphins are found in tropical and temperate waters
around the world from roughly 45[deg] N. to 45[deg] S. (Leatherwood and
Reeves, 1983) but are also known to occur in latitudes greater than
45[deg] in multiple locations within both hemispheres (e.g., United
Kingdom, northern Europe, South Africa, New Zealand, and Tierra del
Fuego; Ross 1979; Jefferson et al. 2008; Olavarria et al. 2010; Goodall
et al. 2011). The species includes coastal populations that migrate
into bays, estuaries, and river mouths, as well as offshore populations
that inhabit pelagic waters along the continental shelf. Movement
patterns of bottlenose populations vary, with some exhibiting long-term
residency, seasonal migrations, or even fully pelagic lifestyles.
Individual ranges can be influenced by water temperature and associated
prey distributions (Hansen 1990; Wells et al., 1990), and use of
separate areas to hunt for various preferred prey is not uncommon
(Defran et al., 1999; Sotckin et al., 2006). Other factors that may
affect habitat use include predation pressure (Mann et al. 2000;
Heithaus and Dill 2002) and anthropogenic disturbance (Lusseau 2005b;
Bejder et al. 2006).
Bottlenose dolphins have a discontinuous distribution within the
coastal waters of both the North and South Islands of New Zealand. The
three main coastal regions where they commonly occur are along the
northeastern coast of the North Island, Marlborough Sounds, and
Fiordland (Figure 1).
Bottlenose dolphins have been reported in many of the fiords within
Fiordland, and sightings along the west coast down to Stewart Island
off the southern coast of the South Island are fairly common (Boisseau
2003). Scientific surveys within Fiordland were first initiated in 1990
(Boisseau 2003), but have focused on only a few

[[Page 35308]]

of the 14 fiords where bottlenose dolphins are known to occur. The
Doubtful-Thompson Sound complex (hereafter Doubtful Sound)--the second
largest and best studied of the fiords--hosts a small, resident
population of bottlenose dolphins. Bottlenose dolphins also occur in
the Dusky- Breaksea Sound complex (hereafter Dusky Sound) and Milford
Sound; however, surveys of these fiords are more limited. Anecdotal
reports have been made of large groups of bottlenose dolphins in Dagg
Sound and Preservation Inlet, which lie to the north and south of Dusky
Sound, respectively (Figure 1; Boisseau 2003); and, between 1996 and
2009, there were five reports of groups of 5 to over 100 individuals
(Currey 2008b) in Chalky and Preservation Inlets (Figure 1). Based on
very limited photo-identification data, these dolphins were presumed to
be visitors from one or more other populations and not Fiordland
residents (Currey 2008b). We are not aware of any dedicated survey
efforts in these fiords where dolphins have been occasionally reported.
For those fiords that have been surveyed, more detailed information on
the range and distribution of the dolphins is summarized below.
The bottlenose dolphins in Doubtful Sound have been described as
being highly resident: Almost all adults are observed during each
survey (Henderson et al. 2013), and re-sighting probabilities are
extremely high (mean = 0.9961, 95% CI: 0.9844-0.9991; Currey et al.
2009b). However, the range of these dolphins is not fully understood
and may be changing. A review of historical sightings data indicates
that during 1994-2003, there were only three instances of five or more
dolphins leaving the fiord for more than 3 consecutive days (Henderson
et al. 2013). Boisseau (2003) also reported that on rare occasions,
single dolphins and mother-calf pairs from this fiord made offshore
forays and were absent from the fiord for weeks to months. In 2009, a
group of 15 dolphins that were photo-identified residents of Doubtful
Sound were photographed in Dagg Sound (Henderson et al. 2013). Since
then, the number of documented occurrences of dolphins leaving the
fiord has increased in frequency (Henderson et al. 2013). Between
November 2009 and October 2011 (with 22-35 total survey days per year),
there have been six documented occasions of groups of 6 to 47 dolphins
leaving the fiord for a minimum of 3 to 7 days. It is unlikely that
dolphins were simply missed during the surveys, because this population
is small (61, CV = 1.46%), the individuals were photo-identified using
strict protocols, and survey effort was relatively high (Henderson
2013a; Henderson et al. 2013). These missing groups included roughly
equal numbers of males and females and included adults, sub-adults, and
calves (Henderson et al. 2013). Every individual in this population was
absent on at least one of these six occasions and on an average of 3.55
of these occasions (SE = 0.28); but all were observed during later
surveys (so had not died or permanently emigrated; Henderson et al.
2013). Causes of this apparent change in residency have not yet been
determined. Destination of the dolphins once they leave is also
unknown; however, on two occasions in 2011, Henderson et al. (2013)
observed large groups moving out of Thompson Sound and heading north,
and there are reports of Doubtful Sound dolphins to the south in Dagg
Sound and Dusky Sound (Currey et al., 2008b, citing L. Shaw, pers.
comm.; Tezanos-Pinto et al. 2010, citing G. Funnell, pers. comm.).
Surveys of Dusky Sound are more limited. Currey et al. (2008c)
obtained an asymptotic discovery curve and a high re-sighting rate of
bottlenose dolphins in this fiord complex during summer 2007/2008, and
thus concluded the dolphins were resident at least over the limited
study period. Following the same survey methods as Currey et al.,
(2008c), Henderson (2013a) conducted surveys from February 2009 to
February 2012 in Dusky Sound (about 34 survey days per year), and after
the first survey in 2009, did not identify any ``new'' dolphins (other
than calves), which is further indication of population residency.
During all of the surveys spanning 2007-2012, groups of 2-5 dolphins
were missing on four occasions (Henderson 2013a). These ``missing''
dolphins were typically older males, and because they were always
present in later surveys, permanent emigration was ruled out. Dusky
Sound is relatively large, so it is possible the surveys failed to
capture these particular dolphins. There are only two documented cases
where dolphins identified as part of the Doubtful Sound population have
been observed in Dusky Sound (Currey et al., 2008b, citing pers. comm.
(Lance Shaw)): In 2003, two older males from Doubtful Sound were
observed in the presence of other bottlenose dolphins, and one of the
two (``Quasimodo'') was observed in Dusky Sound again in 2005.
Within northern Fiordland, bottlenose dolphins have been most
studied within Milford Sound, where dolphins are present throughout the
year and where there is a significant amount of boat traffic and
tourism. The bottlenose dolphins of Milford Sound are part of a more
transient population that ranges across at least 6 fiords, several
bays, and a lake system from Lake McKerrow south to Charles Sound
(Figure 1; (Lusseau 2005a). Some photo-identified individuals have even
been reported just north of Fiordland in Jackson Bay, which lies about
60 km north of Lake McKerrow (Russell et al., 2004; as cited in
Tezanos-Pinto et al., 2010). Given that Milford Sound is relatively
small (15.7 km long, 1.6 km wide on average; Stanton & Pickard, 1981),
it is probably not adequate to support a resident population (Lusseau
and Slooten 2002). Published surveys of the remainder of the known
range of these dolphins appear to be lacking.
Seasonal and spatial distribution patterns of bottlenose dolphins
appear to vary among fiords. In Doubtful Sound, the dolphins show a
preference for the inner fiords during summer and the outer fiord
during winter and spring (Elliott et al. 2011; Henderson 2013b). This
pattern was positively correlated with surface water temperature, and
dolphins were rarely sighted in water below 8[deg] C (Henderson 2013b).
It is possible that the dolphins prefer warmer water or that they are
following seasonal changes in prey distributions. However, it is likely
that thermal stress on calves, which are born in the summer and autumn,
explains the dolphins' avoidance of the inner fiords during winter
months ((Elliott et al. 2011). In all seasons, the dolphins remained
close to the fiord walls (Henderson 2013b). In contrast, during their
early and late summer surveys of Dusky Sound, Currey et al. (2008c)
found that the dolphins occurred throughout the entire fiord system. In
a separate study, the dolphin distribution within Dusky Sound was
positively correlated with surface water temperature during winter
only, and in no season were the dolphins found in close association
with the fiord walls as in Doubtful Sound (Henderson 2013b). Currey et
al. (2008c) hypothesize that the differences in seasonal distributions
for the Doubtful and Dusky sounds, which are only 46 km apart at their
entrances, are due to oceanographic conditions specific to each fiord.
Distribution patterns of bottlenose dolphins within the northern
fiords are not yet well understood and have only been evaluated in
Milford Sound. Gaskin (1972, as cited in Lusseau, 2005) indicated that
during ship surveys from 1968-1970, bottlenose dolphins were commonly
observed in Milford Sound in summer but rarely during winter. Sighting
network data for 1996-1999 also suggest that bottlenose dolphins are

[[Page 35309]]

less common in this fiord during colder months (Lusseau and Slooten
2002). However, a more recent study, in which Lusseau (2005b) surveyed
Milford Sound with equal effort across four seasons, indicated that the
dolphins occur in the sound more frequently in winter (December-
February). Lusseau (2005b) proposed this change in habitat usage may be
the result of increased boat traffic in Milford Sound during the summer
season.
[GRAPHIC] [TIFF OMITTED] TN19JN15.000

Habitat

Fiordland is a mountainous region extending along more than 200 km
of the southwest coast of the South Island (Figure 1). It includes 14
major fiords and their associated arms. The 14 fiords range in length
from 15 km to 38 km (Gibbs et al. 2000) and can reach depths greater
than 400 m (Heath 1985). Carved by Pleistocene glaciers (26,000-18,000
years ago), the 14 major valleys in Fiordland were once freshwater
lakes; then, about 12,000-6,000 years ago, sea level rose above the
terminal moraine or sill at the mouths of the valleys, inundating them
with seawater (Wing and Jack 2014). The underwater sills (30-145 m
deep) still partially separate the fiords from the Tasman Sea (Heath
1985). The region receives a tremendous

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amount of orographic precipitation (i.e., relief-associated rainfall)--
up to 6-8 m per year (Gibbs et al. 2000). The large volume of
freshwater input along with the deep bathymetry, narrow tidal range,
and somewhat limited ocean swell within the inner fiords, contribute to
a persistent and precipitous salinity stratification within the fiords
(Wing and Jack 2014). Greater wave action and mixing, however, occurs
near the fiord entrances (Wing and Jack 2014). Temperature of the low
salinity upper layer varies seasonally and typically ranges from 12-17
[deg]C, but can reach temperatures as low as 4 [deg]C in some areas
during winter (Heath 1985; Henderson 2013b).
The fiords support highly endemic and diverse invertebrate and
microalgae communities (Wing and Jack 2014). The inner fiords are
characterized by an abundance of sessile invertebrate communities that
include species of bivalves, tube worms, bryozoans, sponges,
brachiopods, cnidarians and ascidians (Wing and Jack 2014). Closer to
the fiord entrances, there is a dramatic transition to macroalgae
communities and kelp forests (Wing and Jack 2014). The diversity of
habitats across the depth and length of each fiord support many higher
tropic level consumers, including deep water species like rattails
(Caelorinchus spp.) and hagfish (Eptatretus cirrhatus), rocky reef
species like spotty (Notolabrus celidotus) and conger eel (Conger
verrauxi), and pelagic fishes like mackerel (Scomber australasicus and
Trachurus declivis). The most heavily fished species in Fiordland are
blue cod (Parapercis colias), the red rock lobsters (Jasus edwardsii),
and sea perch (Helicolenus percoides).
Fiordland is only sparsely populated by people but does support
considerable tourism (hiking, scenic cruises, diving, etc.). In 1952,
New Zealand established the Fiordland National Park, which covers an
area of 1.26 million hectares. The national park is also recognized as
a United Nations Educational, Scientific and Cultural Organization
(UNESCO) World Heritage Site, Te W[amacr]hipounamu. Bordering the
national park are 10 marine reserves, ranging in size from 93 to 3,672
hectares. In total, the marine reserves cover more than 10,000 hectares
of marine habitat within the inner fiords.

Life History and Reproduction

The bottlenose dolphin lifespan is 40-45 years for males and more
than 50 years for females (Hohn et al., 1989). Long-term observations
of identifiable dolphins in Fiordland suggest some may be as old as 40
years (Boisseau 2003; Reynolds et al. 2004). Age at sexual maturity in
bottlenose dolphins varies by population and ranges from 5-13 years for
females and 9-14 years for males (Mead and Potter 1990). In a long-term
study within Doubtful Sound, Henderson et al. (2014) calculated a mean
age of 11.33 years (95% CI: 10.83-11.83) at first reproduction for
three females of known age.
Single calves are born after a gestation period of about a year,
but weaning and calving intervals vary among populations. Calves are
nursed for a year or longer and remain closely associated with their
mothers. On average, calving occurs every 3 to 6 years, and calves
remain associated with their mothers for roughly 3-6 years (Read et al.
1993). The calving interval of bottlenose dolphins in Doubtful Sound
ranges from 1 to 10 years and is highly dependent upon calf survival
(Henderson 2013b). For example, Henderson (2013b) found that when
calves died within a month of birth, their mothers could produce
another calf the following year; and, for mothers with calves surviving
for longer than a year, the average inter-calving interval was 5.3
years.
In general, bottlenose dolphin length at birth is about 0.9 m to
1.2 m (Leatherwood et al., 1983). To our knowledge, sizes of calves
born in Fiordland have not been reported. Based on laser photogrammetry
measurements of dorsal fin base length, Rowe et al. (2010) found that
calves in Doubtful Sound (n = 4) were smaller at first measurement than
calves in Dusky Sound (n = 11), suggesting they were either born later
in the season or were smaller at birth.
While calving can occur throughout the year, seasonal peaks in
calving occur in many populations, especially those in cooler,
temperate regions (Urian et al. 1996; Henderson et al., 2014). The
bottlenose dolphins of Doubtful Sound show a strong birthing peak in
warmer months of the austral summer (Boisseau 2003). In a 16-year study
(1995-2011), Henderson et al. (2014) documented that calving in
Doubtful Sound occurs from October-April but mainly takes place during
December-February, when average water temperatures grow increasingly
warmer. Calving in Dusky Sound appears to have a less pronounced
seasonal peak and occurs from early December to May or June (Rowe et
al. 2010).
Reproductive life is fairly long in bottlenose dolphins, and
females as old as 48 years have been known to raise healthy calves
(Boisseau 2003). Additional, specific life history information for
bottlenose dolphins within Fiordland is lacking.

Diet and Foraging

Bottlenose dolphins are generalists and eat a wide variety of
fishes and invertebrates that reflects both their preferences and the
availability of prey (Corkeron et al. 1990). They are known to forage
both individually and cooperatively and use multiple strategies to
capture prey, such as passive listening, prey herding, and ``fish
whacking'' using their flukes (Reynolds et al. 2000).
Stomach content analyses for Fiordland bottlenose dolphins are not
available. However, a stable isotope analysis comparing isotope ratios
in exfoliated skin tissue samples from dolphins (n = 11) inside
Doubtful Sound provides some indirect information on their diet
(Lusseau and Wing 2006). This analysis suggests that, at least within
Doubtful Sound, the dolphins' diet consists mainly of reef-associated
fish (e.g., wrasses, perch, eel) and other demersal fish species (e.g.,
cod, sea perch; Lusseau and Wing 2006). Pelagic fishes, which enter the
fiord from the adjacent Tasman Sea (e.g., mackerel and squid), and
other deep basin species (e.g., hagfish and rattails) do not appear to
comprise much of the dolphins' diet (Lusseau and Wing 2006). These
results are consistent with observations of dolphins spending the
majority of their time and diving mostly in areas associated with rocky
reefs along the fiords' walls or sills in which demersal and reef-
associated fish are most commonly found. In Milford Sound, tour
operators have reported observing bottlenose dolphins feeding on
yellow-eyed mullet, flounder, eels and trout (Lusseau and Slooten
2002).
For dolphins in Doubtful Sound, some observations suggest
cooperative feeding through synchronous diving, and tour operators in
Milford Sound have reported observing bottlenose dolphins cooperatively
feeding on yellow-eyed mullet by herding and trapping them against the
wall of the fiord (Lusseau and Slooten 2002). However, individual
diving and feeding appear to be more common (Boisseau 2003). Passive
acoustic monitoring of dolphins within Doubtful Sound suggests that the
dolphins forage more frequently at dawn and especially dusk (Elliott et
al. 2011).

Mortality

Natural predators of bottlenose dolphins are mainly shark species,
including bull, dusky, and tiger sharks (Shane et al. 1986). Bottlenose
dolphins in Fiordland are observed with scars

[[Page 35311]]

that may be from shark-attacks (Boisseau 2003), but predation rates
have not been estimated. Anthropogenic sources of mortality appear to
be limited and may predominately consist of boat strikes, which have
been the focus of some conservation concerns (Lusseau 2005; Lusseau et
al. 2006). The mortality rate for the dolphins in Doubtful Sound has
been estimated at 8% per year, which is similar to rates measured for
coastal populations in Florida (e.g., 7-9%; Boisseau 2003).

Behaviors

In general, the daily behaviors of bottlenose dolphins are
categorized into several activities, such as travelling, socializing,
foraging, milling, or resting. Activity budgets may depend on seasonal,
ecological, and other factors (Reynolds et al. 2000). In Doubtful
Sound, the group behavioral budget has been quantitatively divided into
travelling, resting, milling, diving, and social behaviors (Boisseau
2003). About half of the dolphins' behavioral budget is spent on
travelling, which in this case, is defined as movement in a uniform
direction with short, regular dive intervals (Boisseau 2003). The
dolphins' behaviors also appear to vary between the warmer, summer
months and the colder, winter months. In the warmer summer months, the
dolphins spend about 12 percent of their time milling and about 22
percent of their time socializing. (``Milling'' is defined as no net
movement of the group, with individuals typically surfacing facing
different directions. ``Socializing'' involves many aerial behaviors,
physical contact, and the formation of small, tightly spaced clusters.)
In winter, these activities accounted for only 4 percent (milling) and
11 percent (socializing) of the budget (Boisseau 2003). Presumably, the
increase in social behaviors in the summer is associated with mating
activities. In winter, diving also increases to about 22 percent of the
budget (versus 16 percent in summer), possibly reflecting higher energy
requirements in colder months (Boisseau 2003). In Milford Sound, the
dolphins spend a greater proportion of their overall behavioral budget
diving compared to the dolphins in Doubtful Sound (32 percent versus 22
percent; Boisseau, 2003). Socializing (15 percent) and resting (9
percent) are smaller portions of the overall budget for Milford Sound
dolphins when compared to those in Doubtful Sound (20 percent and 13
percent, respectively). Boisseau (2013) hypothesized that the dolphins
use Milford Sound primarily as a foraging ground.
In the wild, bottlenose dolphins may occur alone but are often
observed in groups. Group sizes are highly variable and depend on a
range of physical and biological factors such as physiography, prey
availability, and behavioral state (Shane et al. 1982; Reynolds et al.
2000). In general, group size tends to increase with water depth or
distance from shore (Shane et al. 1982; Reynolds et al. 2000). Coastal
groups often contain about 2-15 dolphins, compared to offshore groups,
which can contain about 25 to over a thousand dolphins (Reynolds et al.
2000; Scott and Chivers 1990; Leatherwood et al. 1983). Social
structure within bottlenose dolphin populations is described as being a
``fission-fusion'' structure in which smaller groups form, but group
membership is dynamic and can change on a fairly frequent basis (e.g.,
hours to days; Connor et al. 2000). This fission-fusion society
involves long-term, repeated associations between and among individual
dolphins rather than constant associations; however, some long-term
stable associations between individual dolphins are also observed and
can last for years or decades (Reynolds et al. 2000).
Based on seven years of systematic surveys in Doubtful Sound (1995-
2001), Lusseau et al., 2003 reported an average group size of 17.2
dolphins (median = 14, n = 1,292), with a skewed distribution towards
smaller groups sizes (mode = 8). Most groups were of mixed sex, and the
social structure appeared to consist of three main groups, each with a
large proportion of strong and relatively stable relationships (Lusseau
et al. 2003). In Dusky Sound, a median group size of 11.3 dolphins
(quartiles: 25% = 6.0, 75% = 19.2; n = 46) was reported by Lusseau and
Slooten (2002) based on sightings network data from 1996 to 1999. For
Milford Sound, Lusseau and Slooten (2002) reported that group size
ranged from less than 5 to more than 40, with a median of 16.4
(quartiles: 25% = 9.0, 75% = 22.7; n = 508). Group size in Milford
Sound also varied across the length of the fiord, with larger groups
more common at the entrance to the fiord, and smaller groups typically
found within the fiord (X\2\ = 33.71, df = 12, p <0.001; Lusseau and
Slooten 2002). Understanding of the social structure within the fiords
to the north and south of Doubtful Sound is lacking (Boisseau 2003).

Abundance and Trends

Monitoring of the bottlenose dolphins within Doubtful Sound has
been ongoing since 1990, and using data from standardized surveys
conducted during 1990-1992, Williams et al. (1993) applied three
different models to estimate a total population size of about 58
dolphins. Based on a survey completed in 2007, Currey et al. (2007)
estimated a total population size of 56 dolphins (1.0% CV); and most
recently, Henderson (2013a) estimated a population size of 61 dolphins
(CV = 1.5%) for 2012. Other than calves, no new dolphins have been
sighted in this fiord since 2004; thus, immigration is probably rare
(Currey et al. 2007; Henderson 2013a). Based on sightings data from
2007-2011, adult survival rates are very high (0.988, 95% CI: 0.956-
0.997), and despite an increase since 2010, calf survival rates are
quite low (0.622, 95% CI: 0.435-0.830; Henderson 2013a). Between 1995
and 2011, the average birth rate for dolphins in Doubtful Sound was
4.11 calves per year (SD = 2.49; Henderson 2013b). The majority of runs
(62%) of an age-structured stochastic population model indicate this
population is declining (Henderson 2013b).
Bottlenose dolphin surveys in Dusky Sound were initiated in 2007,
and based on survey data from 2007-2008, Currey and Rowe (2008)
estimated a resident population totaling 102 bottlenose dolphins (CV =
0.9%). More recently, Henderson (2013a) completed a 4-year survey of
Dusky Sound in 2012 and reported a population census of 124 dolphins,
which closely matched the match-recapture estimate of 122 dolphins (CV
= 0.83%). Henderson (2013a) also reported that no new adults or sub-
adults have been identified in this fiord since 2009, suggesting that
immigration may be rare. Adult survival rates in Dusky Sound are high
(0.966, 95% CI: 0.944-0.98), but calf survival rates are quite low
(0.722, 95% CI: 0.556-0.844, Henderson 2013a). The majority of runs
(60%) of an age-structured stochastic population model indicate a
negative population trend (Henderson 2013b).
The bottlenose dolphin abundance within Milford Sound has been
estimated to be only about 45 to 55 total individuals (Lusseau et al.
unpubl. data, as cited in Lusseau 2005). Boisseau (2003) also reported
a provisional abundance estimate of 47 individuals (CV = 6.5%) for
Milford Sound. It is unclear how fully these estimates account for the
other 6 fiords that this northern community of dolphins is known to use
as part of its range. To our knowledge there are no other abundance
estimates or trend information available for this population.
Based on the separate abundance estimates for Doubtful, Dusky, and
Milford Sounds, the total abundance of

[[Page 35312]]

bottlenose dolphins in Fiordland is probably close to 200 dolphins.
Similarly, based on recent abundance estimates for Doubtful and Dusky
Sounds and stochastic modeling for Milford Sound, Currey et al. (2009a)
estimated a total population of 205 bottlenose dolphins in Fiordland
(CV = 3.5%, 95% CI: 192-219). Using stochastic age-structured Leslie
matrix population models, Currey et al. (2009a) also projected that the
Fiordland population was highly likely to decline over the next one,
three, and five generations.

Distinct Population Segment Analysis

The following sections provide our analysis of whether the
petitioned entity--the bottlenose dolphins occurring within the waters
of Fiordland, New Zealand--qualify as a DPS of Tursiops truncatus. To
complete this analysis we relied on the best scientific and commercial
data available, and we considered all literature and public comments
submitted in response to our 90-day finding (79 FR 9880; February 21,
2014).

Discreteness

The Services' joint DPS Policy states that 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.
(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 (61 FR 4722;
February 7, 1996).
For purposes of this analysis, we defined the population segment of
bottlenose dolphins of Fiordland to consist of the three communities
that occur regularly in, or originate from, Milford Sound, Doubtful
Sound and Dusky Sound. We use the term ``community'' here to mean a
group of dolphins that share a common home range; whereas, we use the
term ``population'' to apply more strictly to a closed reproductive
unit. We considered the range of the possible Fiordland DPS to extend
as far north as Jackson Bay. The more transient community of dolphins
that occur in Milford Sound may range at least as far north as Jackson
Bay, which is about 60 km north of Lake McKerrow at the northern edge
of Fiordland (Figure 1; Russell et al. 2004, as cited in Tezanos-Pinto
et al. 2010). Groups of bottlenose dolphins ranging in size from 2 to
over 100 dolphins have been occasionally sighted as far south as
Preservation Inlet but are of unknown origin (Currey 2008b). Lacking
any basis to exclude the southernmost fiords, we considered the
geographic range of the possible Fiordland population segment to extend
as far south as Preservation Inlet. Dolphins that are only occasional
visitors and not resident to Fiordland were not considered in our
analysis as part of the potential distinct population segment.
There are no physical barriers preventing migration or movement of
bottlenose dolphins out of Fiordland. Groups of dolphins from both
Doubtful and Dusky Sound are known to have traveled outside their
fiords (Henderson 2013a; Henderson et al. 2013), and are thus not
restricted to a particular fiord. The bottlenose dolphins occurring in
northern Fiordland are also known to range over at least 7 fiords and
possibly as far north as Jackson Bay, and they are considered to have a
home range of at least 250 km (Boisseau 2003). Documented movements of
other coastal populations of bottlenose dolphins in New Zealand
indicate that the bottlenose dolphins elsewhere in New Zealand waters
undertake long migrations. For example, a photo-identified bottlenose
dolphin was sighted off of Westport only 66 days after having been
sighted in Marlborough Sounds, indicating it had covered over 370 km in
a maximum of 66 days (Figure 1; Brager and Schneider 1998). The
bottlenose dolphins that occur in the Bay of Islands, which lies at the
northernmost end of the North Island of New Zealand, are also known to
travel to the Hauraki Gulf, over two hundred kilometers to the south
(Berghan et al., 2008), and their range, at minimum, extends 82 km
north and 388 km south of the Bay of Islands (Constantine 2002).
Despite the long-range movements and lack of physical barriers, the
closest bottlenose dolphin sightings north of Fiordland come from
Westport, which is about 400 km north along the coast from Jackson Bay,
and dolphins are only reported to occur there occasionally (Brager and
Schneider 1998). Similarly, bottlenose dolphins have only been
occasionally sighted in the southernmost fiords, to the south of Dusky
Sound (Figure 1; Boisseau 2003; Henderson 2013a). Thus, there may be
some degree of geographic separation of the Fiordland population as a
consequence of existing distribution patterns.
A range of physiological, ecological, and behavioral factors can
act as mechanisms to create or maintain separation among populations.
In this particular case, we examined possible mechanisms, such as
breeding cycles, diet, foraging strategies, and acoustic repertoires
that could contribute to the marked separation of the Fiordland
dolphins. As discussed previously, the breeding and birthing cycles of
the Fiordland dolphins are seasonal, with births peaking in the warmer
months. This reproductive cycle, however, is likely to coincide or at
least overlap with that of other New Zealand populations. For example,
for the Bay of Islands population in the North Island of New Zealand,
the majority of calves are born in the summer months (Constantine
2002). In fact, most global populations exhibit diffuse seasonality,
with birthing peaks occurring in the warmer months (Urian et al. 1996).
The varied diet and variety of foraging strategies that have been
reported for dolphins in Fiordland suggest that these factors are also
unlikely to create ecological barriers to mixing with other populations
or communities. The acoustic repertoire of Fiordland dolphins is highly
diverse and does include some vocalizations that may be unique to
Fiordland (Boisseau 2005). However, many of the vocalizations are
similar to those reported elsewhere (Boisseau 2005), and acoustic
studies on other coastal New Zealand bottlenose dolphin populations
appear to be lacking, thereby precluding comparisons. Other relevant
data, such as social organization within and among communities of
bottlenose dolphins of coastal New Zealand, also appear to be very
limited and could not provide evidence of marked separation. After
examining the best available information, we ultimately concluded there
is insufficient evidence of particular physiological, ecological, or
behavioral mechanisms contributing to the marked separation of the
Fiordland dolphins from other bottlenose dolphin populations.
As highlighted in the DPS Policy, quantitative measures of
morphological discontinuity or differentiation can serve as evidence of
marked separation of populations. We examined whether the morphological
data for bottlenose dolphins in Fiordland, which come from a limited
number of dolphins from Doubtful Sound, provide evidence of marked
separation of the Fiordland dolphins. As discussed previously, the
asymptotic total length for adult bottlenose dolphins in Doubtful Sound

[[Page 35313]]

is predicted to reach at least 3.2 m, which is about 30 percent longer
than adult bottlenose dolphins from the warmer-water populations in
Texas and Florida (Perrin, 1984, Chong and Schneider 2001). Based on
stereophotogrammetric measurements, fluke width and anterior flipper
length also appear to be proportionately smaller for bottlenose
dolphins in Doubtful Sound when compared to stranded bottlenose
dolphins from Texas (Chong and Schneider 2001). The morphology of the
Doubtful Sound dolphins is consistent with the general pattern of
increasing body size with decreasing water temperatures and is similar
to that of other deeper water populations and populations in higher
latitudes (Ross and Cockcroft 1990; Hersh and Duffield 1990).
Bottlenose dolphins elsewhere in New Zealand also exhibit longer body
sizes, and as noted by Constantine (2002), the bottlenose dolphins in
the Bay of Islands ``appear to be morphologically the same as those in
Marlborough Sounds and Doubtful Sound.'' In the Bay of Islands, which
lies along the northeast coast of the North Island, four corpses of
presumed members of that region's coastal population, had measured
lengths of 2.84 m, 3.12 m, 3.13 m, and 3.16 m, comparable to the
estimated length of Fiordland dolphins (Constantine 2002, citing
unpublished data). Other data, such as skull measurements, which would
allow for additional morphological comparisons, do not appear to be
available for the Fiordland dolphins. Overall, we concluded there is no
evidence of marked separation of the Fiordland population segment on
the basis of a quantitative morphological discontinuity.
Photo-identification libraries, in which known individuals are
catalogued based on dorsal fin markings, have been generated and
maintained for many of the coastal populations of bottlenose dolphins
in New Zealand, including Doubtful, Milford and more recently, Dusky
Sound. These libraries allow tracking of the demographics and
individual status of dolphins within the dolphin communities. Over 17
years of photo-identification records have been amassed from surveys of
Doubtful Sound and provide firm evidence that the dolphins of Doubtful
Sound are fairly resident and have a high degree of natal philopatry
(Henderson et al. 2013; Henderson et al. 2014). In surveys conducted
from 2009-2012 in Dusky Sound, Henderson (2013a) also reported that no
new adults or sub-adults were identified in the fiord after 2009,
suggesting that immigration is limited or rare. While movements of
dolphins outside of their main fiord have been documented, especially
for Doubtful Sound, no permanent emigration has been reported, and the
only new individuals identified in each community have been calves
(Henderson 2013a). The lack of documented emigration or immigration in
the datasets for both Doubtful and Dusky Sounds is a strong indicator
that these communities are probably closed, and thus markedly separate
from other coastal New Zealand or pelagic populations. Although there
remains some uncertainty given the limited data for the community that
frequents Milford Sound and for dolphins occurring in the southernmost
fiords, we consider the survey data for Doubtful and Dusky Sounds, the
two largest fiord systems in Fiordland, to be evidence of the
demographic independence of the Fiordland population and thus marked
separation of the Fiordland population segment from other bottlenose
dolphin populations.
The hypothesis that the Fiordland dolphins are demographically
independent is supported by genetic data that indicate restricted gene
flow among New Zealand bottlenose dolphin populations. Analyses of
mitochondrial DNA (mtDNA) control region sequences (n = 193) and 11
nuclear microsatellite loci (nuDNA, n = 219) indicate that three
discontinuous, coastal populations of bottlenose dolphins in New
Zealand--the northeastern North Island, Marlborough Sounds, and
Fiordland populations--are relatively genetically isolated from each
other (overall mtDNA Fst = 0.15, p < 0.001; overall nuDNA Fst = 0.09, p
< 0.001; Tezanos-Pinto et al. 2008; Tezanos-Pinto et al. 2010). All
pairwise comparisons of the three sample populations based on both
mtDNA and nuDNA also indicate significant genetic differentiation (p <
0.001 for all Fst comparisons, Tezanos-Pinto et al. 2010). Within the
Fiordland sample, which included samples collected from Jackson Bay (n
= 5) and Doubtful Sound (n = 14), three dolphins shared an mtDNA
haplotype with the North Island population and one dolphin shared a
haplotype with the Marlborough Sounds population (Tezanos-Pinto et al.
2010). The remaining four haplotypes in the Fiordland sample were
unique to the Fiordland dolphins (Tezanos-Pinto et al. 2010). Tezanos-
Pinto et al. (2010) found no evidence of genetic sub-structuring within
the combined Fiordland sample (i.e. Jackson Bay and Doubtful Sound);
however, sample sizes were too small to allow rigorous statistical
analysis. Tezanos-Pinto et al. (2008) also conducted a global
assessment of genetic structure within T. truncatus by pooling the
mtDNA samples for the three New Zealand populations and comparing that
pooled sample to 13 other regional populations or subpopulations from
the South Pacific, North Pacific and Atlantic Oceans (n = 579).
Overall, all sample populations were significantly differentiated (Fst
= 0.16, [Fcy]st = 0.34, p< 0.0001), and all pair-wise comparisons with
the New Zealand sample population were also significant (p < 0.0055;
Tezanos-Pinto et al. 2008); however, there were no phylogeographically
distinct lineages at a regional scale. Tezanos-Pinto et al. (2010) also
noted that the relatively large number of mtDNA haplotypes (n = 6) and
high levels of haplotype and nucleotide diversity for the Doubtful
Sound sample (h = 0.82 0.056, nucleotide diversity = 1.54
percent 0.83) are inconsistent with expectations of
genetic drift in a small isolated population (e.g., < 50 mature
females). This diversity could reflect relatively recent isolation or
periodic interbreeding with neighboring communities or pelagic
populations. We further note there are significant limitations of the
currently available data due to the lack of genetic samples from the
pelagic populations off New Zealand and from other communities within
Fiordland. Thus, there is still considerable uncertainty regarding the
degree of genetic isolation of the bottlenose dolphins within
Fiordland, and further research is needed to more fully resolve the
population structure.
Although the currently available genetic data do not support a
conclusion that the Fiordland bottlenose dolphin population segment
constitutes a completely separate population segment, the available
genetic data do indicate varying magnitudes of differentiation of New
Zealand dolphins from other global populations. Considering the
available genetic data and the evidence of closed populations within
Fiordland, we conclude that the weight of the evidence is sufficient to
indicate that the Fiordland bottlenose dolphins are markedly separated
from other populations of T. truncatus. Thus, after considering the
best available data and information, we conclude that the Fiordland
population segment of bottlenose dolphins is ``discrete.'' We therefore
proceeded to evaluate the best available information with respect to
the second criterion of the DPS Policy.

[[Page 35314]]

Significance

Under the DPS Policy, if a population segment is found to be
discrete, then its biological and ecological significance to the taxon
to which it belongs is evaluated. This consideration may include, but
is not limited to: (1) Persistence of the discrete population segment
in an ecological setting unusual or unique for the taxon; (2) evidence
that the loss of the discrete population segment would result in a
significant gap in the range of a taxon; (3) evidence that the discrete
population segment represents the only surviving natural occurrence of
a taxon that may be more abundant elsewhere as an introduced population
outside its historical range; and (4) evidence that the discrete
population segment differs markedly from other populations of the
species in its genetic characteristics (61 FR 4722, February 7, 1996).
Significance of the discrete population segment is not necessarily
determined by the existence of one of these classes of information
standing alone. Accordingly, all relevant and available biological and
ecological information for the discrete population segment is
considered in evaluating the discrete population segment's importance
to the taxon as a whole.

Persistence in an Ecological Setting Unusual or Unique for the Taxon

Bottlenose dolphins occur in a wide range of habitat types around
the world. Within the range of the species, there is no typical or
usual habitat type in terms of water depth, proximity to shore, water
temperature, salinity, or prey resources. Provided there are sufficient
prey resources, bottlenose dolphins can be successful in very diverse
habitat conditions. For example, bottlenose dolphins occur in shallow,
coastal bays, lagoons and estuaries; waters around oceanic islands; and
in deep, offshore waters. They are found in warm, tropical waters as
well as colder temperate waters, generally no farther than 45 degrees
North or South (Leatherwood and Reeves 1983). The waters of Fiordland
are an example of a colder, deeper water, coastal habitat at the
southern limit of the species' range. Other and even more extreme
occurrences of bottlenose dolphins have been recorded in relatively
cold and/or deep-water habitats in the northern hemisphere, such as in
Moray Firth, Scotland (57 degrees N; Cheney et al. 2013) and off the
coast of Norway (Tomilin 1957, as cited in Kenney 1990) and southern
Greenland (Leatherwood and Reeves 1982), and in the southern
hemisphere, for example in the Patagonian and Fuegian channels and
fiords (as far as 53 degrees S; Olavarria et al. 2010; Cheney et al.
2013). Thus, while Fiordland, New Zealand is a biologically and
geologically unique region towards the southern limit of the species'
range, the persistence of bottlenose dolphins in this region is not in
itself significant to the taxon as a whole.
The Petitioner asserted that Fiordland bottlenose dolphins have
developed adaptations in response to their persistence in their cold-
water habitat and that these differences qualify them as
``significant'' under the DPS Policy. Specifically, the Petitioner
cites the larger body size as an adaptation stemming from their cold-
water habitat and an indicator of the ``significance'' of the Fiordland
dolphins. The Petitioner also discusses the dolphins' ``unusual''
seasonal distribution patterns, larger group sizes, and distinct social
structure. Thus, we considered possible adaptations to the particular
ecological setting and whether they indicate that the bottlenose
dolphins in Fiordland are ``significant'' to the taxon as a whole.
As discussed previously, the morphology of the Fiordland bottlenose
dolphins appears to be consistent with the general pattern of
increasing body size with decreasing water temperatures, similar to
that of other deep water populations and populations in higher
latitudes (Hersh and Duffield 1990; Ross and Cockcroft 1990;
Constantine 2002). For example, bottlenose dolphins found in Tierra del
Fuego, South America, reach lengths over three meters, and eastern
North Atlantic dolphins, like those in Moray Firth, Scotland, measure
as long as 3.8 m (Perrin and Reilly 1984; Goodall et al. 2011). Even
larger body lengths of up to 4.1 m have been recorded for bottlenose
dolphins in the northeastern Atlantic (Connor et al. 2000, citing
Frazer 1974 and Lockyer 1985). It has been hypothesized that a larger
body size provides a thermal advantage in colder water by reducing the
surface-area-to-volume ratio (Ross and Cockcroft 1990). In colder
waters, the proportionally smaller appendages may also help minimize
heat loss by decreasing the surface area-to-volume ratio (Boisseau
2003; Ross and Cockcroft 1990). Likewise, smaller body sizes and
proportionally larger flippers in warmer waters may in part be a
consequence of the greater requirement for heat dissipation (Hersh and
Duffield 1990). This pattern of increased body size and smaller
appendages is common in both terrestrial and marine species found
across a wide range of latitudes, and is thus not unique to bottlenose
dolphins (Boisseau 2003; Reynolds et al. 2000). In summary, the
Fiordland population's morphological characteristics are neither
unexpected given its habitat nor unobserved in other bottlenose dolphin
populations. This information strongly suggests that larger body size
is not a unique adaptation to Fiordland but is part of the observed
variability for the taxon; therefore, we conclude this characteristic
does not qualify this population segment as significant to the taxon as
a whole.
In general, group sizes observed for the Fiordland bottlenose
dolphin communities are considered relatively large. As discussed
earlier, group sizes vary among the three Fiordland communities, and
the reported medians from a study of all three communities were 11.3 (n
= n = 46), 16.4 (n = 508), and 21.2 (n = 568) for Dusky, Milford, and
Doubtful Sound, respectively (Lusseau and Slooten 2002). In Milford
Sound, group size also varied significantly depending on location
within the fiord, with larger groups being more common near the
entrance to the fiord (Lusseau and Slooten 2002). Based on observations
of 1,292 groups followed in Doubtful Sound from 1995 to 2001, Lusseau
et al. (2003), found that group sizes ranged from less than 5 to over
55 dolphins and averaged 17.2 dolphins (median = 14).
Although large compared to many coastal, resident populations, the
reported group sizes for the Fiordland dolphins is not dissimilar from
group sizes reported for other coastal populations in New Zealand. For
example, group size for bottlenose dolphins in the Bay of Islands was
found to range from an average of 18.1 dolphins in Spring (median = 20,
range = 2-50, n = 31) down to a low of 13.8 in Winter (median = 12,
range = 2-40, n = 50, Constantine 2002). Dwyer et al. (2013) reported a
high level of year-round use of the waters off the west coast of Great
Barrier Island, which lies at the outer edge of Haukari Gulf, North
Island, by ``large groups'' with a median size of 35 (other statistics
were not available). Lastly, in the Marlborough Sounds, South Island,
group size was found to range from 3-172 dolphins, with a median size
of 12 (n = 45, SD = 38), and with most groups (n = 34) containing more
than 11 dolphins (Merriman et al. 2009).
Group size for Fiordland dolphins is also similar to, or even
smaller than, group sizes reported for bottlenose dolphins occurring in
the comparably cold and deep water habitats of Patagonia. Based on 32
separate sightings recorded during 2001-2010 in the Patagonian fiords
of southern Chile, Olavarria et al. (2010) reported that

[[Page 35315]]

group size ranged from 2-100 and averaged 25 dolphins. Similarly, in
eight sightings of bottlenose dolphin groups over the course of 14
surveys during 2000-2001 in the northern Patagonia fiords of southern
Chile, Viddi et al. (2010) reported group sizes of 4-100 dolphins and
an average group size of 34. In addition, when compared to other
bottlenose populations generally, the group sizes reported for
Fiordland are well within the observed variability. For example, Scott
and Chivers (1990) reported fairly large mean and median group sizes of
94 and 12, respectively, for coastal bottlenose dolphins in the eastern
tropical Pacific Ocean (n = 867); and Zaeschmar et al. (2013) reported
groups sizes ranging from 2-250 dolphins and averaging 62.8 dolphins in
waters off the northeastern coast of the North Island, New Zealand (n =
36, SD = 42.8).
Group size may be affected by factors such as presence of
predators, prey availability, habitat complexity, season, and activity
type (e.g., foraging, breeding; Shane et al. 1986; Heithous and Dill
2002; Gowans et al. 2008). Whether and how these and other ecological
factors influence group size has received inconsistent support in the
literature, complicating researchers' ability to establish general,
consistent relationships between group size and ecological factors
(Scott and Chivers 1990; Corkeron 1997; Gygax 2002; Gowans 2008). It
remains unclear the extent to which variation in group size across the
species is a result of random historical processes versus selective
pressures (Gygax 2002). Perhaps lesser but additional complications
hampering interpretations of group size are the differing perceptions
of what constitutes a group, and inconsistencies among studies in terms
of the criteria used to define ``a group'' (Shane et al. 1986; Connor
et al. 2000).
Overall, given the natural variability of group size observed in
bottlenose dolphins, the similarity of group sizes within Fiordland to
those reported elsewhere, and the lack of a clear understanding of the
drivers of this variation, we find there is insufficient evidence that
the group sizes reported for Fiordland communities reflect a special or
unique adaptation to their habitat such that it qualifies the
population segment as ``significant'' to the taxon as a whole.
A characteristic related to group size is social structure, and as
discussed earlier, bottlenose dolphins are highly social animals
exhibiting a ``fission-fusion'' social structure (Connor et al. 2000).
The ``fission-fusion'' social structures of bottlenose dolphins is
highly plastic and ranges dramatically among communities or populations
from being characterized by a high proportion of long-lasting
associations (Lusseau et al. 2003) to consisting mostly of short-term
(several days) associations (e.g., Lusseau et al. 2006). Complexity of
the overall social structure also varies widely and can include few or
many levels of organization and alliances. Influences that contribute
to inter- and intra-population variation in social structure may
include availability of prey, disturbance, dispersal, and other
demographic factors (Ansmann et al. 2012; Augusto et al. 2012; Morteo
et al. 2014; Hamilton et al. 2014). Also, while social structure for a
particular community or population can remain stable over multiple
generations, it is not necessarily a fixed or rigid characteristic for
a particular population or geography and can change in response to
changing conditions, such as changes in fishing practices (Ansmann et
al. 2012).
Doubtful Sound bottlenose dolphins appear to have a relatively
unique social structure that includes a large proportion of strong,
long-lasting associations both within and between sexes (Lusseau et al.
2003). The community structure also seems more stable over time
compared to other populations (Lusseau et al. 2003). However, group
membership was still fluid and thus consistent with a ``fission-
fusion'' model; and, females did display an association pattern similar
to that of populations elsewhere (Lusseau et al. 2003). Lusseau et al.
2003 concluded that the most parsimonious explanation of the observed
social structure is the isolation of the Doubtful Sound community from
other bottlenose communities. According to this hypothesis, the
geographic isolation and consequent lack of immigration and emigration,
promotes the formation of alliances and stability of the overall social
structure. Lusseau et al. (2003) also hypothesized the stable social
structure observed in Doubtful Sound could be driven by the temporally
and spatially variable prey resources within the fiord and a
requirement for greater cooperation among the dolphins in order to
forage efficiently. Data to test either of these hypotheses are not
available. Thus, it is not possible to determine whether the observed
social structure in Doubtful Sound is a special or unique adaptation in
response to ecological constraints, or whether it is simply a
consequence of the community's relative isolation.
To our knowledge, the only study of social structure for bottlenose
dolphins within Fiordland comes from the Doubtful Sound community, and
comparable studies for the remaining fiords appear to be lacking. The
extent to which the social structure of Doubtful Sound can be
extrapolated to the other communities is unknown, especially for the
transient community that occurs in the northern fiords (Boisseau 2003).
Given the unknown social structure of the other Fiordland communities
and the uncertainty of whether the observed social structure in
Doubtful Sound is evolutionarily meaningful, we conclude this
interesting characteristic of the Doubtful Sound community does not
qualify the Fiordland population segment as ``significant'' to the
taxon as a whole.
The Petitioner discusses the seasonal changes in distribution of
the Fiordland dolphins in response to water temperature and asserts
this is relatively unusual behavior. The Petitioner discusses how the
Fiordland dolphins tend to occupy the warmer waters of the inner fiords
during the summer calving season; and in winter, when the inner fiord
waters become colder, the dolphins are found closer to the fiord
entrances. This seasonal change in habitat use has been documented for
the dolphin community in Doubtful Sound (Elliott et al. 2011; Henderson
2013b); however, as discussed in detail previously, it is not
necessarily the case for the other Fiordland communities (Lusseau
2005b, Currey et al. 2008c, Henderson 2013b). Furthermore, seasonal
habitat shifts that are correlated with water temperature are not
uncommon among coastal bottlenose dolphin populations, especially those
at higher latitudes (Shane et al. 1986; Wilson et al. 1997).
Populations at lower-latitudes also show local seasonal changes in
distribution, which may be in response to factors other than water
temperature (Shane et al. 1986). Populations in the western Atlantic
also undergo seasonal migrations that correspond to changes in water
temperature (Connor et al. 2000). Similar to the females in Doubtful
Sound, female dolphins elsewhere have also been observed to make use of
more warmer and more protected areas for calving (Shane et al. 1986;
Wilson et al. 1997). Overall, we conclude that this particular behavior
does not help qualify the Fiordland population segment as
``significant'' to the taxon as a whole.
In summary, while the Fiordland bottlenose dolphins do exhibit
differences from bottlenose dolphin populations in other regions and
habitat types, given the tremendous intraspecific diversity of physical
and

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ecological characteristics of bottlenose dolphins and the noted
inconsistencies and limited information for the Fiordland population
segment, these differences do not set the Fiordland bottlenose dolphins
apart from the remainder of the taxon. Common bottlenose dolphins are
highly adaptable and successfully occupy and persist in a diverse range
of habitat types, including other cold and deep water habitats in both
hemispheres. The available information leads us to conclude that the
particular variations observed for some or all of the Fiordland
bottlenose communities do not make this population segment more
ecologically or biologically important relative to other individual
populations or communities. Therefore, we conclude that persistence of
bottlenose dolphins in Fiordland is not ``significant,'' to the taxon
as a whole.

Significant Gap in the Range of the Taxon

The second consideration under the DPS Policy in determining
whether a population may be ``significant'' to its taxon is whether the
``loss of the discrete population segment would result in a significant
gap in the range of a taxon'' (61 FR 4722, February 7, 1996).
Bottlenose dolphins are distributed worldwide from tropical to cold
temperate waters. The bottlenose dolphins within Fiordland constitute a
very small fraction of the global abundance and occupy a very small
fraction of the global range of this species. The roughly 200 dolphins
occupying the fiords along about 200 km of New Zealand's South Island
represent such a numerically and geographically small portion of the
taxon that the hypothetical loss of the dolphins in this region would
not constitute a significant gap in the range of the species.
Furthermore, groups of dolphins from populations of unknown origin have
been sighted in the waters of Fiordland south of Dusky Sound (Boisseau
2003). There are no reported matches of these dolphins to photo-
identified dolphins of Dusky Sound or any other fiord (Henderson
2013a). Thus, it is possible that dolphins from another population use
portions of Fiordland occasionally and could eventually recolonize a
gap left by the loss of the Fiordland dolphins. There is also no
evidence to suggest that the loss of the Fiordland bottlenose dolphins
would inhibit population movement or gene flow among other populations
of the species. Overall, we conclude that loss of the Fiordland
bottlenose dolphins would not result in a significant gap in the range
of the taxon.

Only Natural Occurrence of the Taxon

Under the DPS Policy, a discrete population segment that represents
the ``only surviving natural occurrence of a taxon that may be more
abundant elsewhere as an introduced population outside its historical
range'' can be evidence indicating that the particular population
segment is significant to the taxon as whole (61 FR 4722, February 7,
1996). This consideration is not relevant in this particular case,
because T. truncatus is widely distributed throughout its historical
range.

Genetic Characteristics

As stated in the DPS Policy, in assessing the significance of a
discrete population, we consider whether the discrete population
segment differs markedly from other populations of the species in its
genetic characteristics (61 FR 4722, February 7, 1996). Therefore, we
examined the available data to determine whether there was a reasonable
indication that the Fiordland bottlenose dolphins differ markedly in
their genetic characteristics when compared to other populations. In
conducting this evaluation, we looked beyond whether the genetic data
allow for discrimination among populations or communities, and instead
we focused on whether the data indicate marked genetic differences that
appear to be significant to the taxon as a whole. In this sense, we
give independent meaning to the ``genetic discontinuity'' of the
discreteness criterion of the DPS Policy and the ``markedly differing
genetic characteristics'' of the significance criterion. Following our
approach in the ESA status review for false killer whales (Pseudorca
crassidens; Oleson et al. 2010), we consider that the strength of
evidence for the genetic consideration of ``significance'' should be
greater than that for ``discreteness,'' and we interpret ``markedly''
in this context to mean that the degree of genetic differentiation is
consistent with a population that could have genetic adaptations to the
local habitat.
As discussed earlier, analyses of both maternally derived mtDNA and
11 nuclear microsatellite loci indicate significant levels of
differentiation among Fiordland, Marlborough Sounds and North Island
bottlenose dolphin sample populations (Tezanos-Pinto et al. 2010).
Pairwise comparisons of the Fiordland sample (n = 18) to the other New
Zealand samples (n = 100, North Island; n = 31, Marlborough Sounds)
based on the 11 microsatellite loci, had statistically significant but
fairly low Fst values (0.056 and 0.139, respectively; p < 0.001),
indicating shallow levels of differentiation, especially between
Fiordland and the North Island (Tezanos-Pinto et al. 2010). Pairwise
comparisons of the sample populations for mtDNA control region
sequences also gave significant Fst values (0.12 and 0.20, p < 0.001,
Tezanos-Pinto et al. 2010) of a relatively low magnitude when compared
to an expected value for populations experiencing one migrant per
generation (i.e., an Fst value of roughly 0.33 for mtDNA), indicating a
lower level of genetic differentiation and thus greater gene flow than
would be expected if there was one migrant per generation. (As a
general rule of thumb, geneticists consider gene flow rates below one
effective migrant per generation as the level at which local adaptation
is likely.) Based on the mtDNA data, Tezanos-Pinto et al. (2008)
estimated migration rates per generation of 4.89 females (CI = 0.02-
20.32) from the North Island to Fiordland and 0.31 females from
Marlborough Sounds to Fiordland (CI = 0.00-3.12), which is consistent
with the finding of a lower degree of divergence between the North
Island and the Fiordland dolphins and the possibility of more than one
migrant per generation.
In addition, and as noted earlier, the genetic samples for the
Fiordland dolphins had high levels of haplotype and nucleotide
diversity (h = 0.82 0.056, nucleotide diversity = 1.54
percent 0.83), which Tezanos-Pinto et al. (2010)
hypothesized could reflect relatively recent isolation or periodic
interbreeding with neighboring communities or pelagic populations. This
high level of genetic diversity also contrasts with the low levels of
genetic diversity reported by Natoli et al. (2004) for coastal
bottlenose dolphin populations sampled from various geographic regions.
As discussed previously, Tezanos-Pinto et al. (2008) also conducted
a global assessment of genetic structure within T. truncatus by pooling
the mtDNA samples for the three New Zealand populations and comparing
that pooled sample to 13 other regional populations from the South
Pacific, North Pacific and Atlantic Oceans (n = 579). All populations
were significantly differentiated (Fst = 0.16, [PHgr]st = 0.34, p
<0.0001); however, there were no phylogeographically distinct lineages
at a regional scale (Tezanos-Pinto et al. 2008). Overall, this
assessment suggests that the coastal and pelagic populations sampled
are interconnected on an evolutionary time scale through long-distance
dispersal (Tezanos-Pinto et al. 2008).

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In summary, the Fiordland bottlenose dolphins display a relatively
high level of genetic diversity, relatively low magnitudes of genetic
differentiation, and may experience gene flow at rates above the level
likely to lead to local adaptation. Mechanisms for the observed genetic
diversity are unknown and may be the result of interbreeding with other
populations or insufficient time for drift or local adaptation to
occur. The extremely limited genetic data for the Milford Sound
community and lack of genetic data for the Dusky Sound community add to
the level of uncertainty regarding the evolutionary significance of
genetic characteristics of the Fiordland population segment. Taken
together, there is insufficient data to show that the genetic
characteristics of the Fiordland bottlenose dolphins differ markedly
from other populations of the species.

DPS Conclusion and ESA Finding

According to our analysis, the Fiordland bottlenose dolphin
population is discrete based on evidence it is a relatively closed and
isolated population segment. However, while discrete, the Fiordland
dolphin population segment does not meet any criteria for significance
to the taxon as a whole. As such, based on the best available data, we
conclude that the Fiordland bottlenose dolphins do not constitute a DPS
and thus do not qualify for listing under the ESA. Therefore, we do not
propose to list this population segment. As this is a final action, we
do not solicit comments on it.

References

A complete list of the references used in this proposed rule is
available upon request (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: June 11, 2015.
Samuel D. Rauch, III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2015-15087 Filed 6-18-15; 8:45 am]
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