[Federal Register: August 9, 2005 (Volume 70, Number 152)]
[Rules and Regulations]
[Page 46365-46386]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09au05-20]
[[Page 46365]]
-----------------------------------------------------------------------
Part VI
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
-----------------------------------------------------------------------
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Determination of
Threatened Status and Special Rule for the Southwest Alaska Distinct
Population Segment of the Northern Sea Otter (Enhydra lutris keny
[[Page 46366]]
oni); Final Rule and Proposed Rule
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AI44
Endangered and Threatened Wildlife and Plants; Determination of
Threatened Status for the Southwest Alaska Distinct Population Segment
of the Northern Sea Otter (Enhydra lutris kenyoni)
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We, the Fish and Wildlife Service (Service), determine
threatened status for the southwest Alaska distinct population segment
of the northern sea otter (Enhydra lutris kenyoni) under the authority
of the Endangered Species Act of 1973, as amended (Act). Once
containing more than half of the world's sea otters, this population
segment has undergone an overall population decline of at least 55-67
percent since the mid-1980s. In some areas within southwest Alaska, the
population has declined by over 90 percent during this time period.
This final rule extends the Federal protection and recovery provisions
of the Act to this population segment.
DATES: This rule is effective on September 8, 2005.
ADDRESSES: The complete file for this final rule is available for
inspection, by appointment, during normal business hours at the Marine
Mammals Management Office, U.S. Fish and Wildlife Service, 1011 East
Tudor Road, Anchorage, Alaska 99503.
FOR FURTHER INFORMATION CONTACT: Douglas Burn, (see ADDRESSES)
(telephone 907/786-3800; facsimile 907/786-3816).
SUPPLEMENTARY INFORMATION:
Background
This section has been updated from the proposed rule to incorporate
comments from peer reviewers, and to include new survey results
collected in 2003 and 2004.
The sea otter (Enhydra lutris) is a mammal in the family Mustelidae
and it is the only species in the genus Enhydra. The overall range of
E. lutris from northern Japan to southern California is approximately
10,000 kilometers (km) (6,212 miles (mi)). There are three recognized
subspecies (Wilson et al. 1991): E. l. lutris, known as the northern
sea otter, occurs in the Kuril Islands, Kamchatka Peninsula, and
Commander Islands in Russia; E. l. kenyoni, also known as the northern
sea otter, has a range that extends from the Aleutian Islands in
southwestern Alaska to the coast of the State of Washington; and E. l.
nereis, known as the southern sea otter, occurs in coastal southern
California. The taxonomy of sea otters is complicated by the lack of
historical information prior to their discovery in 1741, as well as the
population bottlenecks (reductions in genetic diversity as a result of
small population sizes) that resulted from commercial fur harvests that
extirpated the species throughout much of its range. Figure 1 in the
Proposed Rule illustrates the approximate ranges of the three currently
recognized subspecies.
The two subspecies of northern sea otter (E. l. kenyoni and E. l.
lutris) are separated by an expanse of open water that measures
approximately 320 km (200 mi) between the Near Islands of the United
States and the Commander Islands in Russia. Wide, deep-water passes
serve as a barrier to sea otter movements (Kenyon 1969), and
interchange between these two subspecies is considered to be low. (See
later sections on food habits and animal movements.) Genetic analyses
show some similarities between sea otters in the Commander Islands and
Alaska (Cronin et al. 1996), which indicates that movements between
these areas has occurred, at least over evolutionary/geologic time
scales.
The southernmost extent of the range of E. l. kenyoni is in
Washington state and British Columbia, and is the result of
translocations of sea otters from Alaska between 1969 and 1972 (Jameson
et al. 1982). The Washington and British Columbia population is
separated from the nearest sea otters in Alaska by a distance roughly
of 483 km (300 mi) to the north, and is separated from the southern sea
otter (E. l. nereis) by a distance of more than 965 km (600 mi) to the
south.
It is the smallest marine mammal in the world, except for the South
American marine otter (Lontra (= Lutra) felina) (Reidman and Estes
1990). Adult males average 130 centimeters (cm) (4.3 feet (ft)) in
length and 30 kilograms (kg) (66 pounds (lb)) in weight; adult females
average 120 cm (3.9 ft) in length and 20 kg (44 lb) in weight (Kenyon
1969). The northern sea otter in Russian waters (E. l. lutris) is the
largest of the three subspecies, characterized as having a wide skull
with short nasal bones (Wilson et al. 1991). The southern sea otter (E.
l. nereis) is smaller and has a narrower skull with a long rostrum and
small teeth. The northern sea otter in Alaska (E. l. kenyoni) is
intermediate in size and has a longer mandible than either of the other
two subspecies.
Sea otters lack the blubber layer found in most marine mammals and
depend entirely upon their fur for insulation (Riedman and Estes 1990).
Their pelage consists of a sparse outer layer of guard hairs and an
underfur that is the densest mammalian fur in the world, averaging more
than 100,000 hairs per square centimeter (645,000 hairs per square
inch) (Kenyon 1969). As compared to pinnipeds (seals and sea lions)
that have a distinct molting season, sea otters molt gradually
throughout the year (Kenyon 1969).
Sea otters have a relatively high rate of metabolism as compared to
land mammals of similar size (Costa 1978; Costa and Kooyman 1982,
1984). To maintain the level of heat production required to sustain
them, sea otters eat large amounts of food, estimated at 23-33 percent
of their body weight per day (Riedman and Estes 1990). Sea otters are
carnivores that primarily eat a wide variety of benthic (living in or
on the sea floor) invertebrates, including sea urchins, clams, mussels,
crabs, and octopus. In some parts of Alaska, sea otters also eat
epibenthic (living upon the sea floor) fishes (Estes et al. 1982; Estes
1990).
Much of the marine habitat of the sea otter in southwest Alaska is
characterized by a rocky substrate. In these areas, sea otters
typically are concentrated between the shoreline and the outer limit of
the kelp canopy (Riedman and Estes 1990), but can also occur further
seaward. Sea otters also inhabit marine environments that have soft
sediment substrates, such as Bristol Bay and the Kodiak archipelago. As
communities of benthic invertebrates differ between rocky and soft
sediment substrate areas, so do sea otter diets. In general, prey
species in rocky substrate habitats include sea urchins, octopus, and
mussels, while in soft substrates, clams dominate the diet.
Sea otters are considered a keystone species, strongly influencing
the species composition and diversity of the nearshore marine
environment they inhabit (Estes et al. 1978). For example, studies of
subtidal communities in Alaska have demonstrated that, when sea otters
are abundant, epibenthic herbivores such as sea urchins will be present
at low densities whereas kelp, which are consumed by sea urchins, will
flourish. Conversely, when sea otters are absent, grazing by abundant
sea urchin populations creates areas of low kelp abundance, known as
urchin barrens (Estes and Harrold 1988).
Sea otters generally occur in shallow water areas near the
shoreline. They
[[Page 46367]]
primarily forage in shallow water areas less than 100 meters (m) (328
ft) in depth, and the majority of all foraging dives take place in
waters less than 30 m (98 ft) in depth (Bodkin et al. 2004). As water
depth is generally correlated with distance to shore, sea otters
typically inhabit waters within 1-2 km (0.62-1.24 mi) of shore (Riedman
and Estes 1990). While sea otters can also be found at greater
distances from shore, this typically occurs in areas of, or near,
shallow water. For example, a broad shelf of shallow water extends
several miles from shore in Bristol Bay, along the north side of the
Alaska Peninsula. Prior to the onset of the sea otter population
decline (described below), large rafts of sea otters were commonly
observed above this shelf of shallow water at distances as far as 40 km
(25 mi) from shore (Schneider 1976).
Movement patterns of sea otters have been influenced by the
processes of natural population recolonization and the translocation of
sea otters into former habitat. While sea otters have been known to
make long distance movements up to 350 km (217 mi) over a relatively
short period of time when translocated to new or vacant habitat (Ralls
et al. 1992), the home ranges of sea otters in established populations
are relatively small. Once a population has become established and has
reached equilibrium density within the habitat, movement of individual
sea otters appears to be largely dictated by environmental and social
factors, including gender, breeding status, age, climatic variables
(e.g. weather, tidal state, season), and human disturbance, as
described below.
Home range and movement patterns of sea otters vary depending on
the gender and breeding status of the otter. In the Aleutian Islands,
breeding males remain for all or part of the year within the bounds of
their breeding territory, which constitutes a length of coastline
anywhere from 100 m (328 ft) to approximately 1 km (0.62 mi). Sexually
mature females have home ranges of approximately 8-16 km (5-10 mi),
which may include one or more male territories. Male sea otters that do
not hold territories may move greater distances between resting and
foraging areas than territorial males (Lensink 1962, Kenyon 1969,
Riedman and Estes 1990, Estes and Tinker 1996).
Juvenile males (1-2 years of age) are known to disperse later and
for greater distances, up to 120 km (75 mi), from their natal (birth)
area than 1-year-old females, for which the greatest distance traveled
was 38 km (23.6 mi) (Garshelis and Garshelis 1984, Monnett and
Rotterman 1988, Riedman and Estes 1990). Intraspecific aggression
between breeding males and juvenile sea otters may cause juvenile
otters to move from their natal areas to lower quality habitat (Ralls
et al. 1996), and survival of juvenile sea otters, though highly
variable, is influenced by intraspecific aggression and dispersal
(Ballachey et al. 2003).
Sea otter movements are also influenced by local climatic
conditions such as storm events, prevailing winds, and in some areas,
tidal states. Sea otters tend to move to protected or sheltered waters
(bays, inlets, or lees) during storm events or high winds. In calm
weather conditions, sea otters may be encountered further from shore
(Lensink 1962, Kenyon 1969). In the Commander Islands, Russia, weather,
season, time of day, and human disturbance have been cited as factors
that induce sea otter movement (Barabash-Nikiforov 1947, Barabash-
Nikiforov et al. 1968).
Due to their dependence on shallow-water feeding areas, most sea
otters in Alaska occur within State-owned waters, which include the
area from mean high tide to 4.8 km (3 mi) offshore, and any that go
further offshore are within the U.S. Exclusive Economic Zone, which
extends 370.4 km (200 nautical miles) seaward from the coast of the
United States.
While sea otters typically rest in the water, they can also haul
out and rest on shore (Kenyon 1969). Female sea otters typically give
birth in the water, however, they have also been observed to give birth
while on shore (Barabash-Nikiforov et al. 1968, Jameson 1983). Although
they typically haul out and remain close to the water's edge, sea
otters have been observed on land at distances up to several hundred
meters from the water (Riedman and Estes 1990). The majority of coastal
lands within the range of the southwest Alaska population of the
northern sea otter are part of the Service's National Wildlife Refuge
(NWR) system, including Alaska Maritime NWR, Izembek NWR, Alaska
Peninsula/Becharof NWR, and Kodiak NWR. The National Park Service also
has large parcels of coastal lands in southwest Alaska, including
Katmai National Park and Aniakchak National Monument and Preserve. The
vast majority of remaining coastal lands in southwest Alaska are owned
by the State of Alaska and Alaska Native Corporations. Privately owned
lands constitute a very minor proportion of coastal lands in southwest
Alaska.
Female sea otters in Alaska live an estimated 15-20 years, while
male lifespan appears to be about 10-15 years (Calkins and Schneider
1985). First-year survival of sea otter pups is generally substantially
lower than that for prime age (2-10 years old) animals (Monson and
DeGange 1995, Monson et al. 2000). Male sea otters appear to reach
sexual maturity at 5-6 years of age (Schneider 1978, Garshelis 1983).
The average age of sexual maturity for female sea otters is 3-4 years,
but some appear to reach sexual maturity as early as 2 years of age.
The presence of pups and fetuses at different stages of development
throughout the year suggests that reproduction occurs at all times of
the year. Most areas that have been studied show evidence of one or
more seasonal peaks in pupping (Rotterman and Simon-Jackson 1988).
Similar to other mustelids, sea otters can have delayed
implantation of the blastocyst (developing embryo) (Sinha et al. 1966).
As a result, pregnancy can have two phases: from fertilization to
implantation, and from implantation to birth (Rotterman and Simon-
Jackson 1988). The average time between copulation and birth is 6-7
months. Female sea otters typically will not mate while accompanied by
a pup (Lensink 1962; Kenyon 1969; Schneider 1978; Garshelis et al.
1984). The interval between pups is typically 1 year.
Estes (1990) estimated population growth rates ranging from 17-20
percent per year for four northern sea otter populations expanding into
unoccupied habitat. While Bodkin et al. (1999) also reported similar
population growth rates, they also note that population growth rates in
translocated populations were significantly greater than for remnant
populations. After the initial period of growth, populations typically
reach an equilibrium density, defined as the average density,
relatively stable over time, that can be supported by the habitat
(Estes 1990).
Distribution and Status
Historically, sea otters occurred throughout the coastal waters of
the north Pacific Ocean, from the northern Japanese archipelago around
the north Pacific rim to central Baja California, Mexico. The historic
distribution of sea otters is depicted in Figure 2 of the Proposed
Rule.
Prior to commercial exploitation, the range-wide estimate for the
species was 150,000-300,000 individuals (Kenyon 1969, Johnson 1982).
Commercial hunting of sea otters began shortly after the Bering/
Chirikof expedition to Alaska in 1741. Over the next 170 years, sea
otters were hunted to the brink of extinction first by Russian, and
later by American, fur hunters.
[[Page 46368]]
Sea otters became protected from commercial harvests under the
International Fur Seal Treaty of 1911, when only 13 small remnant
populations were known to still exist (Figure 2 in the Proposed Rule).
The entire species at that time may have been reduced to only 1,000-
2,000 animals. Two of the 13 remnant populations (Queen Charlotte
Island and San Benito Islands) subsequently became extinct (Kenyon
1969, Estes 1980). The remaining 11 populations began to grow in
number, and expanded to recolonize much of the former range. Six of the
remnant populations (Rat Islands, Delarof Islands, False Pass, Sandman
Reefs, Shumagin Islands, and Kodiak Island) were located within the
bounds of what we now recognize as the southwest Alaska population of
the northern sea otter (see Distinct Vertebrate Population Segment).
All 6 of these remnant populations grew during the first 50 years
following protection from further commercial hunting. At several
locations in the Aleutian Islands, the rapid growth of sea otter
populations appears to have initially exceeded the carrying capacity of
the local environment, as sea otter abundance at these islands then
declined, either by starvation or emigration, eventually reaching
equilibrium density (Kenyon 1969).
Population Trends of Sea Otters in Southwest Alaska
The following discussion of population trends is related to the
southwest Alaska distinct population segment of sea otters addressed in
this final rule. The southwest Alaska population ranges from Attu
Island at the western end of Near Islands in the Aleutians, east to
Kamishak Bay on the western side of lower Cook Inlet, and includes
waters adjacent to the Aleutian Islands, the Alaska Peninsula, the
Kodiak archipelago, and the Barren Islands (see Figure 3 of the
Proposed Rule).
Survey methods vary in different locations. In some parts of
southwest Alaska, sea otters have been counted from boats or aircraft
within a narrow band of water adjacent to the shoreline; in others,
transects have been used to sample an area, and the resulting sea otter
density is extrapolated to generate a population estimate for the
entire study area. Like survey efforts of most species, detection of
all the individuals present is not always possible. Sea otters spend
considerable time under water, and it is not possible to detect
individuals that are below the surface at the time a survey is
conducted. Also, observers do not always detect every individual
present on the surface. Only a few surveys have been conducted using
methods that allow for calculation of a correction factor to adjust for
the estimated proportion of otters not detected by observers. One way
to make this adjustment requires an independent estimate of the actual
number of otters present in an area, also known as ``ground-truth,''
combined with the regular survey data in order to calculate a
correction factor to adjust for sea otters not detected during the
survey. Thus, survey results can be of several types: they can be
direct counts or estimates, either of which may be adjusted or
unadjusted for sea otters not detected by observers. In areas where we
compare unadjusted sea otter counts or estimates, we assume that there
is no significant difference between the proportion of otters not
detected by observers.
In the following discussion of population trends, results are
presented separately for surveys conducted in the Aleutian Islands, the
Alaska Peninsula, the Kodiak Archipelago, and Kamishak Bay. For the
Alaska Peninsula, results are presented for various surveys that have
been conducted for north Peninsula offshore areas, south Peninsula
offshore areas, south Alaska Peninsula Islands, and the South Alaska
Peninsula shoreline. The general locations of the survey areas are
depicted in Figure 4 A-D of the Proposed Rule.
Unless otherwise specified, the survey results are unadjusted for
otters not detected by observers. Within each study area, recent
surveys were conducted using methods similar to those used in the past,
so that counts or estimates would be as comparable as possible with
baseline information for that area. Although there may be slight
differences in the time of year that surveys were conducted, we do not
believe these timing differences hinder comparisons of survey results
because otters are likely to remain in the same general area, as they
are not migratory. A summary of sea otter survey data from each survey
area within the southwest Alaska population is presented in Table 1,
followed by a narrative description of the results for each area.
Table 1.--Summary of Sea Otter Population Surveys in Southwest Alaska
[Estimates include 95 percent confidence intervals where available. Estimates for the Kodiak archipelago and
Kamishak Bay are the only values adjusted for sea otters not detected.]
----------------------------------------------------------------------------------------------------------------
Survey area Year Count or estimate Source
----------------------------------------------------------------------------------------------------------------
Aleutian Islands............... 1965 9,700........................ Kenyon (1969).
1992 8,048........................ Evans et al. (1997).
2000 2,442........................ Doroff et al. (2003).
North Alaska Peninsula Offshore 1976 11,681....................... 9,215 3,709 (AUG)
Areas. * 1986 6,474 2,003 7,539 2,103 (OCT)
(JUN). Schneider (1976).
Brueggeman et al. (1988),
Burn and Doroff (2005).
...................................
2000 4,728 3,023 Burn and Doroff (2005).
(MAY).
South Alaska Peninsula Offshore * 1986 13,900 6,456 Brueggeman et al. (1988),
Areas. ........... (MAR). Burn and Doroff (2005).
........... 14,042 5,178
(JUN).
17,500 5,768
(OCT).
2001 1,005 1,597 Burn and Doroff (2005).
(APR).
South Alaska Peninsula Islands. 1962 2,195........................ Kenyon (1969).
1986 2,122........................ Brueggeman et al. (1988).
1989 1,589........................ DeGange et al. (1995).
2001 405.......................... Burn and Doroff (2005).
South Alaska Peninsula 1989 2,632........................ DeGange et al. (1995).
Shoreline. 2001 2,651........................ Burn and Doroff (2005).
Kodiak Archipelago............. 1989 13,526 2,350.... DeGange et al. (1995).
1994 9,817 5,169..... Doroff et al. (in prep.).
[[Page 46369]]
2001 5,893 2,630..... Doroff et al. (in prep.).
2004 6,284 1,807..... Doroff et al. (in prep.).
Kamishak Bay................... 2002 6,918 4,271..... USGS in litt. (2002).
----------------------------------------------------------------------------------------------------------------
*Estimates recalculated by the Service (Burn and Doroff 2005) from original data of Brueggeman et al. (1988).
Aleutian Islands
The first systematic, large-scale population surveys of sea otters
in the Aleutian Islands (Figure 4A of the Proposed Rule) were conducted
from 1957 to 1965 by Kenyon (1969). The descendants of two remnant
colonies had expanded throughout the Rat, Delarof, and western
Andreanof Island groups. The total unadjusted count for the entire
Aleutian archipelago during the 1965 survey was 9,700 sea otters. In
1965, sea otters were believed to have reached equilibrium densities
throughout roughly one-third of the Aleutian archipelago, ranging from
Adak Island in the east to Buldir Island in the west (Estes 1990).
Islands in the other two-thirds of the archipelago had few sea otters,
and researchers expected additional population growth in the Aleutians
to occur through range expansion.
From the mid-1960's to the mid-1980's, otters expanded their range,
and presumably their numbers as well, until they had recolonized all
the major island groups in the Aleutians. Although the maximum size
reached by the sea otter population is unknown, a habitat-based
computer model estimates that the population in the late-1980s may have
numbered approximately 74,000 individuals in the Aleutians (Burn et al.
2003).
In a 1992 aerial survey of the entire Aleutian archipelago, we
counted a total of 8,048 otters (Evans et al. 1997), approximately
1,650 (19 percent) fewer than the total reported for the 1965 survey.
Although sea otters had recolonized all major island groups, they had
unexpectedly declined in number by roughly 50 percent in portions of
the western and central Aleutians since 1965, based on a comparison of
the 1965 and 1992 survey results. Sea otter surveys conducted from
skiffs during the mid-1990s also indicated substantial declines at
several islands in the western and central Aleutians (Estes et al.
1998). It was not known at the time if these observed declines were
representative of the entire Aleutian sea otter population or merely a
local phenomenon.
In April 2000, we conducted another complete aerial survey of the
Aleutian archipelago. We counted 2,442 sea otters, which is a 70-
percent decline from the count 8 years previously (Doroff et al. 2003).
Along the more than 5,000 km (3,107 miles) of shoreline surveyed, sea
otter density was at a uniformly low level, which clearly indicated
that sea otter abundance had declined throughout the archipelago.
The aerial and skiff survey data both indicate that the onset of
the decline began in the latter half of the 1980s or early 1990s.
Doroff et al. (2003) calculated that the decline proceeded at an
average rate of -17.5 percent per year in the Aleutians. Although
otters declined in all island groups within the archipelago, the
greatest declines were observed in the Rat, Delarof, and Andreanof
Island groups. This result was unexpected, as the remnant colonies in
these island groups were the first to recover from the effects of
commercial harvest, and sea otters were believed to have been at
equilibrium density at most of these islands in the mid-1960s.
Doroff et al. (2003) used skiff-based counts at six islands in the
western and central Aleutians as ground-truth data, and calculated that
aerial observers detected roughly 28 percent of the sea otters present.
Adjusting for otters not detected by observers, the estimated
population size in April 2000 was 8,742 sea otters. Additional skiff-
based surveys at these islands conducted in the summer of 2003
indicated that the sea otter population has declined by a further 63
percent at an estimated annual rate of 29 percent per year (Estes et
al. 2005). If the declines at these islands are representative of the
Aleutian archipelago as a whole, the entire population in this area may
number as few as 3,311 individuals.
In July 2004, we also conducted aerial surveys of sea otters at
several islands in the eastern Aleutians using the same methods as the
2000 survey. Due to dense fog, we were only able to survey 223 km of
the total shoreline (62 percent). In 2000 we counted 73 otters within
this surveyed area, but only 38 otters there in 2004; a decline of 48
percent, at an estimated annual rate of 15 percent per year (USFWS in
litt.). These results indicate that similar to the western and central
Aleutians, the sea otter decline has not abated in the eastern
Aleutians.
Alaska Peninsula
Three remnant colonies (at False Pass, Sandman Reefs, and Shumagin
Islands) were believed to have existed near the western end of the
Alaska Peninsula after commercial fur harvests ended in 1911 (Kenyon
1969). During surveys in the late 1950s and early 1960s, substantial
numbers of sea otters were observed between Unimak Island and Amak
Island (2,892 in 1965) on the north side of the Peninsula, and around
Sanak Island and the Sandman reefs (1,186 in 1962), and the Shumagin
Islands on the south side (1,352 in 1962) (Kenyon 1969).
As summarized in Table 1 and described below, surveys of sea otters
along the Alaska Peninsula have covered four areas, with the same
method used in a given area. For the north Alaska Peninsula offshore
area (Figure 4B of the Proposed Rule), shoreline counts are not an
appropriate survey method due to the broad, shallow shelf in Bristol
Bay, a condition under which sea otters occur further from the shore
than elsewhere. Consequently, the north Alaska Peninsula offshore area
has been surveyed from aircraft using north-south transects extending
from the shoreline out over the shelf. Using this method, Schneider
(1976) calculated an unadjusted population estimate of 11,681 sea
otters on the north side of the Alaska Peninsula in 1976, which he
believed to have been within the carrying capacity for that area.
Brueggeman et al. (1988) conducted replicate surveys of the same area
during three time periods in 1986. We re-analyzed the original 1986
survey data to address computational errors in the survey report; our
re-calculated estimates range from 6,474-9,215 sea otters for this area
for the three surveys in 1986 (Burn and Doroff 2005). In May 2000, we
replicated the survey design of Brueggeman et al. (1988) using
identical
[[Page 46370]]
survey methods. The 2000 survey estimate of 4,728 sea otters indicates
abundance on the north side of the Alaska Peninsula had fallen by 27-49
percent in comparison with the minimum and maximum point estimates of
the 1986 survey (Burn and Doroff 2005).
The largest aggregations of sea otters in May 2000 were observed in
Port Moller. This concentration of sea otters has been described as a
seasonal phenomenon, as surveys conducted later in the summer have not
recorded similar numbers of sea otters (B. Murphy, Alaska Department of
Fish and Game, in litt. 2002). To test this assumption, we conducted
sea otter surveys in the Port Moller, Herendeen Bay, and Nelson Lagoon
areas in May and July 2004 (USFWS in litt. 2004). Sea otter abundance
was high during both survey periods, so it is not clear to what degree
there may be seasonal use of these areas.
Offshore areas on the south side of the Alaska Peninsula (Figure 4B
of the Proposed Rule) were surveyed at three different time periods in
1986 (Brueggeman et al. 1988). Noting computational errors in the
survey report, we re-analyzed the original 1986 survey data, resulting
in estimates of 13,900-17,500 sea otters for the three surveys
conducted in 1986 (Burn and Doroff 2005). We replicated the survey in
April 2001, when our estimate of 1,005 otters for the south Alaska
Peninsula offshore area indicated a decline in abundance of at least 93
percent when compared with the minimum and maximum point estimates in
this area from the 1986 surveys. Specific areas of high sea otter
concentrations in 1986, such as Sandman Reefs, were almost devoid of
sea otters when surveyed in 2001 (Burn and Doroff 2005).
Several island groups along the south side of the Alaska Peninsula
(Figure 4C of the Proposed Rule; Pavlof and Shumagin Islands, as well
as Sanak, Caton, and Deer Islands) are another survey area. In 1962,
Kenyon (1969) counted 1,900 otters along these islands. Twenty-four
years later, in 1986, Brueggeman et al. (1988) counted 2,122 otters in
the same survey area. In 1989, DeGange et al. (1995) counted 1,589
otters along the shorelines of the islands that had been surveyed in
1962 and 1986, which was approximately 16-28 percent fewer sea otters
than were reported in the earlier counts. This decrease was the first
indication of a sea otter population decline in the area of the Alaska
Peninsula. When we counted sea otters in these island groups in 2001,
we recorded only 405 individuals (Burn and Doroff 2005), which is an
81-percent decline from the 1986 count reported by Brueggeman et al.
(1988). We conducted additional aerial surveys at 13 of these islands
in May and July of 2004 using similar methods as in 2001. Sea otter
counts at these islands declined a further 33 percent from 268 to 179
in the past 3 years (USFWS in litt. 2004). Similar to recent surveys in
the Aleutians, these results indicate that the sea otter population
decline in this area has not abated.
The southern shoreline of the Alaska Peninsula from False Pass to
Cape Douglas (Figure 4D of the Proposed Rule) is another survey area.
In 1989, DeGange et al. (1995) counted 2,632 sea otters along this
stretch of shoreline. In 2001 we counted 2,651 sea otters (Burn and
Doroff 2005), nearly the same as the 1989 count. When we subdivided and
compared the results for the eastern and western components of the
survey areas, we found that sea otter density along the eastern end of
the Peninsula, from Cape Douglas to Castle Cape, increased
approximately 4 percent, from 1989 to 2001 (Burn and Doroff 2005). For
the western end of the Peninsula from False Pass to Castle Cape,
however, there was evidence of a population decline, with sea otter
density falling by 35 percent over the same time period. We also
counted 42 sea otters along the shoreline of Unimak Island in 2001, but
there is no suitable baseline data for comparison. Based on what is
known about sea otter movements and the distance between the eastern
and western ends of the Peninsula, we believe that it is unlikely that
these observations represent a change in distribution. In May 2004 we
conducted an aerial survey of Sutwick Island and counted only 23 sea
otters along the shoreline. In May 2001 we counted 73 otters in this
area, which is further evidence that the sea otter decline in southwest
Alaska has not abated (USFWS in litt).
The results from the different survey areas along the Alaska
Peninsula indicate various rates of change. Overall, the combined
counts for the Peninsula have declined by 65-72 percent since the mid-
1980s, based on the data presented in Table 1.
We have calculated an estimate of the sea otter population for the
entire Alaska Peninsula using the most recent survey data, including an
adjustment for otters not detected by observers. In making this
calculation, we first revised the combined total number of sea otters
observed during the most recent surveys (8,789), to account for
potential double-counting in an area of overlap between two of the
study areas along the Peninsula. We then multiplied this revised number
of otters (8,328) by the correction factor of 2.38 provided by Evans et
al. (1997) for the type of aircraft used, to account for otters not
detected by observers. The result is an adjusted estimate of 19,821 sea
otters along the Alaska Peninsula as of 2001.
Kodiak Archipelago
One of the remnant sea otter colonies in southwest Alaska is
thought to have occurred at the northern end of the Kodiak archipelago
(Figure 4D of the Proposed Rule), near Shuyak Island. In 1959, Kenyon
(1969) counted 395 sea otters in the Shuyak Island area. Over the next
30 years, the sea otter population in the Kodiak archipelago grew in
numbers, and its range expanded southward around Afognak and Kodiak
Islands (Schneider 1976, Simon-Jackson et al. 1984, Simon-Jackson et
al. 1985). DeGange et al. (1995) surveyed the Kodiak archipelago in
1989 and calculated an adjusted population estimate of 13,526 sea
otters. In July and August 1994, we conducted an aerial survey using
the methods of Bodkin and Udevitz (1999) and calculated an adjusted
population estimate of 9,817, approximately 27 percent lower than the
estimate for 1989 (Doroff et al. in prep.). In June 2001, we surveyed
the Kodiak archipelago using the same observer, pilot, and methods as
in 1994. The result was an adjusted population estimate of 5,893 sea
otters for the archipelago in 2001 (Doroff et al. prep.), which is a
40-percent decline in comparison to the 1994 estimate and a 56-percent
decline from the 1989 estimate.
In summer 2004 we surveyed the Kodiak archipelago using the same
methods as in 1994 and 2001 and estimated the current population size
at 6,284 sea otters. While this represents a slight increase since
2001, the estimates are not significantly different from one another (Z
= 0.24, p = 0.81; Doroff et al. in prep.). Although these results
suggest that, in contrast to the Aleutian archipelago and Alaska
Peninsula study areas, the sea otter population in the Kodiak
archipelago likely has not declined in the past several years; the
current estimate remains 36 percent lower than in 1994, and 54 percent
lower than in 1989.
Kamishak Bay
Kamishak Bay is located on the west side of lower Cook Inlet, north
of Cape Douglas (Figure 4D of the Proposed Rule). In the summer of
2002, the U.S. Geological Survey (USGS), Biological Resources
Discipline conducted an aerial survey of lower Cook Inlet and the
[[Page 46371]]
Kenai Fiords area. This survey was designed, in part, to estimate sea
otter abundance in Kamishak Bay. The method used was identical to that
of the 2001 aerial survey of the Kodiak archipelago, which includes a
correction factor for sea otters not detected by the observer (Bodkin
and Udevitz 1999). Sea otters were relatively abundant within Kamishak
Bay during the 2002 survey, with numerous large rafts of sea otters
observed. The adjusted estimate for the current sea otter population
size in Kamishak Bay is 6,918 (USGS in litt. 2002). As no previous
estimates for Kamishak Bay exist, the population trend for this area is
unknown.
Overall Comparison
The history of sea otters in southwest Alaska is one of commercial
exploitation to near extinction (1742 to 1911), protection under the
International Fur Seal Treaty (1911), and population recovery (post-
1911). By the mid-to late-1980s, sea otters in southwest Alaska had
grown in numbers and recolonized much of their former range. The
surveys conducted in various areas, described above, provide
information about the geographic extent and magnitude of declines
within those areas. Due to differences in the years of the various
baseline surveys for different areas (1962, 1965, 1976, 1989), it is
difficult to combine those surveys as a basis for estimating the
overall size of the sea otter population throughout southwest Alaska at
the onset of the decline. Therefore, as part of our effort to evaluate
information reflecting the overall magnitude of the decline, we also
have considered information provided by Calkins and Schneider (1985),
who summarized sea otter population estimates worldwide based on data
collected through 1976. Much of the information they present is from
unpublished Alaska Department of Fish and Game survey results, and we
include this information as it is the only comprehensive reference for
estimating the overall magnitude of the sea otter decline in southwest
Alaska.
Calkins and Schneider (1985) provided estimates from survey data
collected as of 1976, adjusted for animals not detected by observers,
for the Aleutian Islands (55,100-73,700), north Alaska Peninsula
(11,700-17,200), south Alaska Peninsula (22,000-30,000) and Kodiak
archipelago (4,000-6,000). They did not report a specific estimate for
the Kamishak Bay area, which presumably was included within their
estimate for the Kenai Peninsula and Cook Inlet area (2,500-3,500
otters), and we are assuming that half of the sea otters estimated for
Kenai Peninsula and Cook Inlet occurred in Kamishak Bay (1,250-1,750).
Combining these estimates, the sea otter population in the area
encompassing the range of the southwest Alaska population was believed
to have numbered between 94,050-128,650 animals as of 1976. As sea
otters had not yet fully recolonized southwest Alaska or reached
equilibrium density in all areas in 1976, additional population growth
was expected. Therefore, the overall population prior to the onset of
the decline in the 1980's probably was higher than the population
estimate for 1976.
Our current estimate of the size of the southwest Alaska population
of the northern sea otter, which includes the 2004 estimate for the
Kodiak archipelago, is 41,865 animals (Table 2). This estimate is based
on range-wide survey information collected from 2000-2004, and is
adjusted for animals not detected. As recent site-specific surveys
indicate the decline has not abated in the Aleutian archipelago and
south Alaska Peninsula study areas, it is possible that the current
population size in 2004 is actually lower.
Table 2.--Recent Population Estimates for the Sea Otter in Southwest Alaska
[Alaska Peninsula and Unimak Island counts are adjusted using a correction factor of 2.38 for twin-engine
aircraft surveys of sea otters according to Evans et al. (1997). Aleutian Islands, Kodiak Archipelago, and
Kamishak Bay surveys are adjusted using survey-specific correction factors.]
----------------------------------------------------------------------------------------------------------------
Unadjusted Adjusted
Survey area Year count or count or Reference
estimate estimate
----------------------------------------------------------------------------------------------------------------
Aleutian Islands.................. 2000 2,442 8,742 Doroff et al. (2003).
North Alaska Peninsula Offshore 2000 4,728 11,253 Burn and Doroff (2005).
Areas.
South Alaska Peninsula Offshore 2001 1,005 2,392 Burn and Doroff (2005).
Areas.
South Alaska Peninsula Shoreline.. 2001 a 2,190 5,212 Burn and Doroff (2005).
South Alaska Peninsula Islands.... 2001 405 964 Burn and Doroff (2005).
Unimak Island..................... 2001 42 100 Burn and Doroff (2005).
Kodiak Archipelago................ 2004 ........... 6,284 Doroff et al. (in prep.).
Kamishak Bay...................... 2002 ........... 6,918 USGS Unpublished data.
--------------
Total......................... ........... ........... 41,865
----------------------------------------------------------------------------------------------------------------
\a\ Does not include a count of 461 sea otters from False Pass to Seal Cape, which was also surveyed as part of
the south Alaska Peninsula Offshore Areas survey.
The 1976 population estimate based on the work of Calkins and
Schneider (1985) is not directly comparable to our current estimate
because of somewhat different survey approaches and estimation
techniques. Nevertheless, the results provide a basis for at least a
rough comparison of the overall extent of the decline of sea otters in
southwest Alaska. When compared to the estimate of 94,050 to 128,650
from Calkins and Schneider (1985), the current estimate of
approximately 41,865 sea otters is 52,185 to 86,785 lower, which is 55
to 67 percent less than the estimate for 1976.
Translocated Sea Otter Populations
As part of efforts to re-establish sea otters in portions of their
historical range, otters from Amchitka Island (part of the Aleutian
Islands) and Prince William Sound were translocated to other areas
outside the range of what we now recognize as the southwest Alaska
distinct population segment, but within the range of E. l. kenyoni
(Jameson et al. 1982). These translocation efforts met with varying
degrees of success. From 1965 to 1969, 412 otters (89 percent from
Amchitka Island, and 11 percent from Prince William Sound, which is in
southcentral Alaska, outside the range of the southwest Alaska DPS)
were translocated to six sites in southeast Alaska (Jameson et al.
1982). In the first 20 years following translocation, these populations
grew in numbers and expanded their range (Pitcher 1989).
[[Page 46372]]
The most recent survey of southeast Alaska, conducted in the summers of
2002 and 2003, estimated the sea otter population at just over 9,000
individuals (USGS in litt. 2003). Comparing this survey with skiff
survey data from the late 1980s, it appears that further range
expansion and population growth in southeast Alaska has not occurred in
the past decade.
Sea otters from Alaska also were translocated to Washington,
Oregon, and British Columbia, Canada, between 1969 and 1972 (Jameson et
al. 1982). Sea otters translocated to British Columbia were captured at
Amchitka Island and Prince William Sound; the otters translocated to
Washington and Oregon were captured at Amchitka Island only. The
British Columbia and Washington populations have grown in number and
expanded their range, while the Oregon population disappeared. The most
recent estimates of population size are 743 in Washington and 2,000 in
British Columbia (Jameson and Jefferies 2004; Watson et al. 1997).
Although these populations, as well as sea otters in southeast Alaska,
are at least in part descended from sea otters at Amchitka Island, they
are geographically isolated from the southwest Alaska population and
their parent population by hundreds of kilometers (see Distinct
Vertebrate Population Segment) and are not included in this proposed
listing action.
The total number of otters removed from Amchitka as part of this
translocation program was just over 600 animals (Jameson et al. 1982).
Estes (1990) estimated that the sea otter population at Amchitka Island
remained essentially stable at more than 5,000 otters between 1972 and
1986, and consequently there is no evidence that removals for the
translocation program were a contributing factor in the current
population decline.
Previous Federal Action
Based on the results of the April 2000 sea otter survey in the
Aleutian Islands, we added sea otters in the Aleutians to our list of
candidate species on August 22, 2000 (65 FR 67343). The Center for
Biological Diversity (Center) filed a petition to list the Aleutian
population of the northern sea otter as endangered on October 26, 2000.
Although the petition referred to it as the ``Aleutian population,''
the verbal description of the geographic extent corresponded to the
southwest Alaska DPS. On November 14, 2000, we received a Notice of
Intent to sue from the Center challenging our decision not to propose
to list sea otters in the Aleutians under the Act. We responded to the
Center that funds were not available during Fiscal Year 2001 to prepare
a proposed listing rule.
On August 21, 2001, we received a petition from the Center to
designate the Alaska stock of sea otters (State-wide) as depleted under
the Marine Mammal Protection Act (MMPA; 16 U.S.C. 1361 et seq.). Under
the MMPA, a marine mammal species or population stock is considered to
be depleted when it is below its Optimum Sustainable Population (OSP)
level. The OSP is defined in the MMPA as: ``the number of animals which
will result in the maximum productivity of the population or the
species, keeping in mind the carrying capacity of the habitat and the
health of the ecosystem of which they form a constituent element.'' In
accordance with the MMPA, we published a notice in the Federal Register
on September 6, 2001, announcing the receipt of this petition (66 FR
4661). On November 2, 2001, we published our finding on the petition in
the Federal Register (66 FR 55693). While we acknowledged the evidence
of a population decline in the southwest Alaska stock, the best
available information at that time suggested that the southeast Alaska
stock was increasing, and the southcentral Alaska stock was either
stable or increasing. We found that the petitioned action was not
warranted under the MMPA for the following reasons: (1) The best
estimate of the population size for the entire State of Alaska was
greater than the value presented in the petition; (2) based on the best
estimate of population size, the Alaska stock of sea otters was above
OSP level; and (3) recent information had identified the existence of
three stocks of sea otters in Alaska: southwest, southcentral, and
southeast (Gorbics and Bodkin 2001). The boundaries of these three
stocks are depicted in Figure 5 of the Proposed Rule.
We recently revised the MMPA stock assessment reports for sea
otters in Alaska. Draft stock assessment reports identifying the three
stocks of sea otters were made available for public review and comment
from March 28 to June 26, 2002 (67 FR 14959) (March 28, 2002). The sea
otter stock assessment reports were finalized on August 20, 2002, and
notice of their availability was published on October 9, 2002 (67 FR
62979).
On January 11, 2002, we received a petition from the Sea Otter
Defense Initiative (SODI), a project of the Earth Island Institute, in
Deer Isle, Maine. The petition requested that we emergency and
permanently list the southwest Alaska stock of sea otters as
endangered. We responded to SODI on February 1, 2002, informing them
that, based on the best available population estimate that we prepared
in response to the Center's petition to list the Alaska stock of sea
otters as depleted under the MMPA, an emergency listing of the
southwest Alaska stock was not warranted. We also notified SODI that we
had begun the preparation of this proposed rule during Fiscal Year
2002.
Based on additional sea otter surveys along the Alaska Peninsula
and Kodiak archipelago, and the identification of multiple stocks of
sea otters in Alaska, we expanded the candidate species designation on
June 3, 2002, to include the geographic range of the southwest Alaska
stock of the northern sea otter. Notification of this change was
included in our June 13, 2002, notice of review of candidate species
(67 FR 40657).
The Center filed a second Notice of Intent to sue on May 5, 2003,
and on December 4, 2003, the Center and the Turtle Island Restoration
Network (TIRN) filed a lawsuit against Assistant Secretary for Fish and
Wildlife and Parks Craig Manson, Secretary of the Interior Gale Norton,
and the U.S. Fish and Wildlife Service for failure to comply with non-
discretionary provisions of the Act. Specifically, the plaintiffs
challenged the defendants' determination that processing the Center's
October 26, 2000, petition was ``warranted but precluded'' by higher
listing actions. Plaintiffs also challenged the defendants' failure to
issue 90-day and 12-month findings on the petition, and for failure to
implement an effective system to monitor the status of the southwest
Alaska DPS. Finally, the plaintiffs challenged the defendants' adoption
and implementation of their 1996 Petition Management Guidance policy
for processing petitions that request the listing of candidate species.
On February 11, 2004, we published the proposed rule to list the
southwest Alaska DPS of the northern sea otter as threatened (69 FR
6600). On May 13, 2004, the December 4, 2003, lawsuit by the Center and
TIRN was voluntarily dismissed.
Summary of Comments and Recommendations
In the February 11, 2004, proposed rule, we requested all
interested parties to submit factual reports, information, and comments
that might contribute to development of a final determination. A 120-
day public comment period closed on June 10, 2004. We contacted
appropriate Federal agencies, State agencies, county and city
governments, Alaska Native Tribes and tribal organizations, scientific
organizations,
[[Page 46373]]
affected landowners and other interested parties to request comments.
The Secretary personally announced this action and issued a press
release on February 5, 2004, notifying the public of the proposed
listing and comment period. Newspaper articles appeared in the
Anchorage Daily News and Los Angeles Times on February 6, 2004, that
also notified the public about the proposed listing and comment period.
We requested 5 peer reviewers to comment on the proposed rule in
compliance with our policy, published in the Federal Register on July
1, 1994 (59 FR 34270). We held public meetings at 6 locations in
Alaska: Cold Bay (May 3, 2004), King Cove (May 4, 2004), Anchorage (May
13, 2004), Kodiak (May 19, 2004), Sand Point (May 24, 2004), and
Unalaska (May 27, 2004). These meetings were attended by approximately
50 people in total.
We received requests for public hearings in Kodiak, Unalaska, Sand
Point, and Dillingham, Alaska, and held one public hearing in Kodiak,
Alaska on May 19, 2004, immediately following a public meeting. We
published an announcement of the public hearing in the Federal Register
on May 5, 2004 (69 FR 25055), the Anchorage Daily News on May 9, 2004,
and the Kodiak Daily Mirror on May 14, 17, 18, and 19, 2004. The public
hearing was attended by 18 individuals in person, and 5 more by
teleconference.
In accordance with Secretarial Order 3225 regarding the Act and
subsistence uses in Alaska, we engaged in government-to-government
consultation with Alaska Native tribes. Since 1997, we have signed
cooperative agreements annually with The Alaska Sea Otter and Steller
Sea Lion Commission (TASSC) to fund their activities. As a tribally-
authorized Alaska Native Organization, TASSC represents the interests
of sea otter hunters throughout the State of Alaska. We attended TASSC
board meetings during the preparation of the proposed rule and public
comment period, regularly briefing their board of commissioners and
staff on relevant issues. In addition to working closely with TASSC, we
sent copies of the proposed rule to 52 Alaska Native Tribal Councils
specifically requesting their comments on this listing action.
During the public comment period, we received a total of 6,860
comments by letter (27), facsimile (4), e-mail (6,819), and public
hearing testimony (10). We received comments from Alaska Native Tribes
and tribal organizations, Federal commissions, State agencies, local
governments, commercial fishing organizations, conservation
organizations, and private citizens. Seventeen commenters opposed the
listing, and 6,831 supported it. The remaining 12 commenters expressed
neither opposition or support for the listing, but voiced concerns
about the possible effects of listing. The vast majority of comments
were the result of an organized e-mail campaign that produced 6,787
identical comments in support of the listing. Most of the comments that
were opposed to the listing were from residents of southwest Alaska.
Several comments were received after the public comment period closed.
We revised the final rule to reflect comments and information we
received during the comment period. We address substantive comments
concerning the rule below. Comments of a similar nature are grouped
together (referred to as ``Issues'' for the purpose of this summary).
Issue 1: Sea Otter Population Decline
Comment 1: One commenter stated that the current population level
of sea otters in southwest Alaska does not warrant listing under the
Act. Two other commenters noted that following protection from
commercial hunting in 1911, the sea otter population recovered from as
low as 1,000-2,000 individuals.
Our Response: Our determination that the southwest Alaska DPS of
the northern sea otter warrants listing as threatened is based on the
observed declining population trend, rather than the absolute number of
sea otters remaining. The definition of a threatened species is one
that is likely to become endangered within the foreseeable future
throughout all or a significant portion of its range. Recent surveys
conducted in 2003 and 2004 indicate that the population decline has not
abated in several areas within southwest Alaska. If the decline
continues at the observed rates, the population may become extirpated
throughout portions of its range within the next decade (Estes et al.
2005), at which point the DPS may be in danger of extinction.
Therefore, the southwest Alaska DPS of the northern sea otter meets the
definition of threatened, as it is likely to become endangered in the
foreseeable future.
Although sea otters rebounded from an estimated 1,000-2,000
individuals after the cessation of commercial hunting, those remaining
otters were distributed in 13 isolated colonies. The current
distribution of sea otters is different in that they occur throughout
their former range, but at extremely low densities in most areas.
Otters are now absent, or nearly so at some of the smaller islands in
the Aleutian archipelago to the point where it is possible that Allee
effects (reduced productivity at low population densities) may occur
(Estes et al. 2005).
The recovery of sea otters following the cessation of commercial
hunting demonstrated that the species has the potential for recovery
once the cause of its decline has been removed. As the cause of the
current decline is not known with certainty, the future recovery of the
southwest Alaska DPS of the northern sea otter is likewise uncertain.
Comment 2: Several commenters state that sea otters have not really
declined, they have simply moved to other areas.
Our Response: Aerial surveys that documented the geographic extent
and magnitude of the sea otter decline covered the vast majority of
available sea otter habitat in southwest Alaska, so it is highly
unlikely that there has been a redistribution of otters within the
region. As sea otters typically inhabit relatively small home ranges,
it is also unlikely that there has been such a large-scale emigration
of animals outside southwest Alaska. The magnitude of the decline is
estimated to be more than 50,000 otters, so it is highly unlikely that
redistribution on this scale would go unnoticed. Survey data in
adjacent areas, such as the Commander Islands, Russia to the west, and
Kachemak Bay, Kenai Fiords, and Prince William Sound to the east, do
not show population increases that would account for animal movements.
See Population Trends of Sea Otters in Southwest Alaska.
Comment 3: Several commenters were critical of the survey data used
to estimate the sea otter population size and trend. Specific
criticisms included the age of the survey data used, the length of time
between surveys, differences in timing of surveys, differences in
methods, and the variability of the estimates.
Our Response: We used the best scientific information available to
estimate sea otter population size and trend. Although some survey data
is now 3-4 years old, more recent surveys in 2003 and 2004 indicate
that the sea otter population decline has not abated. Although the
length of time between surveys makes it difficult to estimate the onset
of the population decline, it does not affect our ability to estimate
the magnitude of the decline. Differences in timing of surveys is
likely not a factor because study areas were large enough that movement
of individual otters would have minimal effect on the overall
population estimate. To the greatest extent possible, aerial surveys
[[Page 46374]]
of sea otters in southwest Alaska have been conducted using similar
methods to earlier surveys to allow for direct comparison of results.
While some of the sea otter population estimates (such as the pre-
decline surveys along the Alaska Peninsula) have considerable
variability, the magnitude of the decline in these areas is so great
that the likelihood that the population has not declined is exceedingly
small.
Comment 4: Several commenters questioned whether sea otters have
declined in some areas within southwest Alaska. Three commenters stated
that there has been no decline of sea otters in the Kodiak archipelago,
and five commenters cited survey data that suggests the population at
Unalaska Island has been stable for the past 4 years.
Our Response: The results of our summer 2004 aerial survey of the
Kodiak archipelago indicate that the sea otters in this area may not
have continued to decline since 2001; however, the two estimates are
not significantly different statistically. The current estimate remains
36 percent lower than in 1994, and 54 percent lower than in 1989
(Doroff et al. in prep.).
Doroff et al. (2003) estimated that the onset of the decline in the
Aleutians occurred in the late 1980s or early 1990s. In 1992, observers
recorded 554 sea otters along the shoreline of Unalaska island. In
2000, only 374 otters were observed, which is a decline of 32 percent
over the intervening 8-year period. By the time that skiff survey data
from Unalaska were collected beginning in 1999, the majority of the
decline had already occurred. It is not possible to determine sea otter
population trends from the Unalaska skiff survey data, as it has not
been standardized by the amount of survey effort to allow for a valid
comparison over time.
Comment 5: Several commenters stated that the sea otters have
exceeded the carrying capacity of the environment, and that decline is
part of a natural cycle. Some commenters stated that archaeological
data shows that changes in sea otter abundance have occurred over time.
Our Response: As sea otters recolonized their former range during
the 20th century, the typically observed pattern was for initial rapid
population growth, followed by a period of decline until the population
reached equilibrium density. The driving factor in the subsequent
decline was prey scarcity, which led to either starvation and/or
emigration of otters. If sea otters had in fact exceeded the carrying
capacity of the environment, we would expect to see fewer prey and more
starving sea otters, neither of which have been observed. Contrary to
this expectation, the biomass of sea urchins, the preferred prey
species of sea otters in the Aleutians, is significantly greater in
areas where otters have declined, and sea otter carcasses are
relatively scarce (Estes et al. 1998).
We are aware of some recent archaeological information from a small
number of sites that indicates the presence of sea otter remains in
midden sites has fluctuated over long time scales; however, several
interpretations are possible from these data. For example, it is not
known if the abundance of items in these sites is a function of their
abundance in the environment or hunter selectivity. It is also not
clear if cultural uses of sea otters may have varied over time,
resulting in changes in the deposition of bones present in middens. For
example, if otters were harvested for their pelts only and the
remainder of the carcass were not retrieved, it is unlikely that their
bones would be represented in midden sites.
Comment 6: One commenter stated that the use of counts in some
areas and estimates in other areas was confusing.
Our Response: We revised the rule to clarify the difference between
the counts and estimates in an earlier section (see Population Trends
of Sea Otters in Southwest Alaska). While there are differences between
the two types of surveys, in all cases we compare counts with counts
and estimates with estimates to determine sea otter population trends.
Comment 7: One commenter stated that there are no reliable
estimates of pre-decline abundance of sea otters in southwest Alaska.
Our Response: We acknowledge that the data record for sea otters in
southwest Alaska is sparse, and that with the exception of Calkins and
Schneider (1985), there are no comprehensive population estimates for
the pre-decline population. Burn et al. (2003) used computer models to
estimate the carrying capacity and pre-decline abundance of sea otters
in the Aleutian islands, and their result was comparable to that of
Calkins and Schneider (1985). Regardless of the lack of a comprehensive
pre-decline estimate, comparisons between baseline (1986-1992) and
recent (2000-2001) surveys clearly indicate that the sea otter
population in southwest Alaska has undergone a substantial decline.
Furthermore, aerial and skiff-based surveys conducted in 2003 and 2004
indicate that the decline has not abated throughout much of the region.
Comment 8: One commenter stated that there appears to be different
rates of decline between the different study areas within southwest
Alaska.
Our Response: This observation is correct. In addition to
differences in the overall magnitude of the decline between study
areas, there are also differences in the estimated annual rates of
decline between regions as well as time periods. For example, Doroff et
al. (2003) estimated that sea otters declined at an annual rate of 17.5
percent per year during the 1990s. During the same time period, sea
otters in the Kodiak archipelago declined at an estimated rate of 6-7
percent per year (Doroff et al. in prep.). More recently, otters in the
western and central Aleutians have declined by an estimated 29 percent
per year between 2000 and 2003 (Estes et al. 2005). As the cause of the
decline is not known with certainty, it is unclear why there are
differences in the estimated rates of decline. That the rates are
different does not alter the fact that the sea otter population has
declined significantly throughout much of southwest Alaska.
Issue 2: DPS Justification
Comment 9: Two commenters stated that the sea otter population in
southwest Alaska does not meet the test of discreteness because it is
not genetically distinct from translocated populations. One commenter
also noted that studies indicate there is further genetic
differentiation of sea otters within southwest Alaska. This commenter
also stated that there is no long-term genetic separation in
evolutionary time, and that there is nothing genetically special about
sea otters in southwest Alaska. Lastly, this commenter stated that the
proposed rule did not consider all available genetics information.
Our Response: Genetic distinctness may be important in recognizing
some DPS's, but this kind of evidence is not specifically required in
order for a DPS to be recognized. Genetic information can play two
different roles in the evaluation of whether a population should be
recognized as a distinct vertebrate population segment for the purposes
of listing under the Act. First, quantitative genetic information may,
but is not required to, provide evidence that the population is
markedly separated from other populations and thus meets the DPS
policy's criterion of being discrete. The DPS policy's standard for
discreteness is meant to allow an entity given DPS status under the Act
to be adequately defined and
[[Page 46375]]
described. The standard adopted is believed to allow entities
recognized under the Act to be identified without requiring an
unreasonably rigid test for distinctness. At the same time, the
standard does not require absolute separation of a DPS from other
members of its species, because this can rarely be demonstrated in
nature for any population of organisms. Second, genetic characteristics
that differ markedly from other populations may be one consideration in
evaluating the DPS's biological and ecological significance to the
taxon in which it belongs.
We considered all available genetic information in our discreteness
evaluation. Some of these studies were specifically conducted to look
at population structuring, while others were designed to look at the
amount of genetic variability of both remnant and translocated sea
otter populations. All existing sea otter populations have experienced
at least one genetic bottleneck caused by the commercial fur harvests
from 1741 to 1911. Translocated populations experienced a second
bottleneck, as it is likely that only an unknown portion of the
available genetic diversity was sampled in the process of moving sea
otters into other areas (Larson et al. 2002). Furthermore, we can
consider an entity eligible for listing if the entity meets the third
factor of our DPS policy: 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 of its
historic range.
Rather than rely on genetic information alone to determine if sea
otters in southwest Alaska are markedly separated from other
populations, we gave considerable weight to the work of Gorbics and
Bodkin (2001), who followed the phylogeographic approach of Dizon et
al. (1992) to identify stock structure. We believe that this approach,
which considers multiple lines of evidence including distribution,
population response, morphology, and genetics, provides a more robust
assessment of separation than any single technique alone.
Comment 10: One commenter stated that morphological differences
between sea otters may reflect differences in environmental conditions,
rather than genetic differences.
Our Response: We agree with this observation, which is one reason
we did not base our determination of discreteness for the DPS on
morphological information alone. As outlined in our response to comment
9, we relied upon a method that considered multiple types of
information including morphology, genetics, and geographic distribution
(Dizon et al. 1992).
Comment 11: One commenter and one peer reviewer questioned whether
Cook Inlet constitutes a barrier to sea otter movements.
Our Response: As the historical distribution of sea otters prior to
the onset of commercial fur harvests in 1741 included ice-free waters
of the Pacific rim from northern Japan to Baja, Mexico, it is clear
that expanses of deep water such as Cook Inlet do not constitute an
impenetrable barrier to animal movements. Available survey information
suggests that this may not be a common occurrence, however. In
accordance with our DPS policy, absolute reproductive isolation is not
a prerequisite to recognition of a DPS. This would be an impracticably
stringent standard, and one that would not be satisfied even by some
recognized species that are known to sustain a low frequency of
interbreeding with related species.
Comment 12: One commenter stated that the Service subdivided the
Alaska population into three population stocks under the MMPA in order
to invoke the Act and list sea otters in southwest Alaska as a DPS.
Our Response: The Service initially proposed the identification of
three stocks of sea otters in Alaska in March 1998 (63 FR 10936). The
preparation of three draft stock assessment reports occurred prior to
both the initial publication of information about the sea otter decline
in the Aleutians (Estes et al. 1998) and completion of aerial surveys
that determined the geographic extent and magnitude of the decline. Our
proposal of three sea otter stocks in 1998 was challenged by the Alaska
Sea Otter Commission (ASOC, name now changed to TASSC), an Alaska
Native Organization, in accordance with Section 117(b)(2) of the MMPA.
The Service and ASOC entered into a memorandum of agreement to resolve
this disagreement. After additional genetic analysis addressing the
issue of stock identification was completed, in March 2002 we once
again proposed the identification of three stocks of sea otters in
Alaska (67 FR 14959). ASOC did not challenge the proposal, and we
finalized the stock assessment reports in August 2002 (67 FR 62979).
The identification of three stocks of sea otters in Alaska was based on
the best available scientific information, that had been published in
peer-reviewed scientific journals and was reviewed and approved by the
Alaska Regional Scientific Review Group that advises the Service on our
stock assessment reports.
Comment 13: One commenter stated that the sea otter population in
southwest Alaska does not meet the test of significance because other
genetic information suggests other population groupings are possible.
Our Response: This comment cited studies that indicate there is a
degree of genetic similarity between sea otters in the Commander
Islands, Russia, and California with otters in southwest Alaska. We
relied on the most recent and generally scientifically accepted
taxonomic classification of the sea otter by Wilson et al. (1991) to
determine the significance of the southwest Alaska DPS to both the
species (Enhydra lutris) and the subspecies (Enhydra lutris kenyoni).
The loss of this population would result in a significant gap of over
2,500 km (1,552 miles) in the range of both the species and subspecies.
Criteria for judging the significance of a DPS includes, but is not
limited to, the four examples listed in our DPS policy (see Distinct
Vertebrate Population Segment). Of the 11 surviving remnant populations
present in 1911, 6 occurred within the range of the southwest Alaska
DPS. Although otters were translocated from Amchitka Island, they were
most likely descended from only one remnant colony. Therefore we
believe the extinction of this DPS would constitute a loss of a
significant portion of the genetic diversity of the taxon.
Issue 3: Causes of the Decline
Comment 14: Several commenters stated that the cause of the decline
is unknown. Other commenters stated that the decline was not caused by
human activities, and one commenter stated that killer whales are not
responsible for the decline.
Our Response: We agree that the cause of the decline is not known
with certainty. Although there is still considerable disagreement
within the scientific community, the weight of evidence at this time
suggests that the cause of the decline may be increased predation by
killer whales. It is not a requirement for listing under the Act that
the threat to a species be caused by human activities, nor is it a
requirement that the cause be known at the time of listing.
Comment 15: One commenter stated that none of the five factors
under the Act are applicable in this instance.
Our Response: The third factor in the five factor analysis
identified in section 4(a)(1) of the Act is Disease or Predation. As
stated in our response to comment 14, the best available scientific
information suggests that the cause of
[[Page 46376]]
the decline may be predation by killer whales, so this factor is
applicable to the sea otter decline.
The fourth factor in the five factor analysis is the Inadequacy of
Existing Regulatory Mechanisms. The MMPA of 1972 is the primary
existing statute that protects sea otters in U.S. waters, yet the
southwest Alaska DPS of sea otters has declined despite these existing
protections. Additional provisions that would regulate subsistence
harvest and minimize incidental take in fisheries are not likely to
help conserve the DPS, as the impact of these factors is believed to be
negligible.
The remaining three factors in the five factor analysis (Habitat,
Overutilization, and Other Natural or Manmade factors), while likely
not causes of the current decline, could become threats to the DPS. If
the current population trend continues, sea otters may disappear from
parts of the range of the DPS, and the remaining areas of high
concentration may be more vulnerable to catastrophic events such as
disease epidemics and oil spills.
Comment 16: Several commenters expressed concern over the impacts
of a variety of human activities, including commercial fisheries, fish
waste from processors, oil spills, and contaminants.
Our Response: As stated in our response to comment 15, we do not
believe that these activities have played a significant role in the sea
otter decline in southwest Alaska, and do not pose an immediate threat
to the DPS. We anticipate that these factors will be more fully
considered during the development of a recovery plan.
Issue 4: Threatened vs. Endangered Status
Comment 17: There were 6,814 commenters who stated that the
southwest Alaska DPS of the northern sea otter should be listed as
endangered rather than threatened. Although these commenters did not
express a rationale for listing at the endangered level, one other
commenter stated that the magnitude of the decline in the Aleutian
islands, which constitute a ``significant portion of the range,''
warrants listing the DPS as endangered.
Our Response: The southwest Alaska DPS contains areas with diverse
population trends, including: (1) The Aleutians and portions of the
Alaska Peninsula that have declined precipitously and are continuing to
decline; (2) the Kodiak archipelago, which has declined overall but not
during the past 3 years; and (3) Port Moller and Kamishak Bay, which do
not appear to have declined, and continue to support high
concentrations of sea otters that have the potential to recolonize the
rest of the DPS. The population trend in the Aleutian archipelago,
which constitutes approximately 30 percent of the available habitat
within the range of the DPS, is a cause for concern: The continuation
of the current trends could lead to the loss of all of the otters in
that area in the foreseeable future. Although that loss would not
result in the extinction of the DPS, it might put the DPS in danger of
extinction at that time (see Conclusion of Status Evaluation).
Therefore, a designation of threatened status is most appropriate for
the southwest Alaska DPS of the northern sea otter.
Issue 5: Subsistence Harvest
Comment 18: Several commenters stated that the subsistence harvest
of sea otters by Alaska Natives is contributing to the sea otter
decline, and that the removal of 100 otters per year from the
population is not prudent. Several other commenters stated that the
subsistence harvest is not contributing to the decline.
Our Response: The best available scientific information does not
indicate that the subsistence harvest has had a major impact on the
southwest Alaska DPS of the northern sea otter. Some of the largest
observed sea otter declines have occurred in areas where subsistence
harvest is either nonexistent (the Near and Rat islands in the
Aleutians) or extremely low (the Shumagin and Pavlof islands). The
majority of the subsistence harvest in southwest Alaska occurs in the
Kodiak archipelago, where the level of subsistence harvest ranged from
0.4-1.3 percent of the estimated population size from 1989'2001 (Doroff
et al. in prep.). Given the estimated population growth rate of 10
percent per year estimated for the Kodiak archipelago by Bodkin et al.
(1999), we would expect that these harvest levels by themselves would
not cause a population decline.
Section 10(e) of the Act provides an exemption that allows Alaska
Natives to take endangered or threatened species for subsistence
purposes. The Service may only prescribe regulations on subsistence
harvest if we determine that such taking materially and negatively
affects the endangered or threatened species. Areas within the
southwest Alaska DPS with the steepest population declines, such as the
Aleutian islands, have virtually no subsistence harvest due to minimal
human habitation. The majority of the subsistence harvest occurs in the
Kodiak archipelago, where the harvest has been well below the estimated
population growth rate. Given the geographic distribution and historic
levels of the subsistence harvest relative to the size of the sea otter
population, we do not believe the harvest is materially and negatively
affecting the DPS at this time. If the sea otter population continues
to decline in southwest Alaska, however, it is possible that the
harvest of 100 otters per year could materially and negatively impact
the remaining population, and regulation of the harvest would be
warranted.
Comment 19: One commenter stated that the subsistence harvest
should be managed. Conversely, several commenters expressed concern
that the rights of Alaska Natives to take sea otters for subsistence
should be protected.
Our Response: In order to regulate the subsistence harvest of sea
otters by Alaska Natives, the Secretary would have to make a
determination that the harvest was materially and negatively impacting
the DPS, and promulgate regulations under Section 10(e)(4) of the Act.
In addition, once it is listed as threatened under the Act, the
southwest Alaska stock of the northern sea otter will automatically be
considered ``depleted'' under the MMPA, and the Secretary could
prescribe regulations of the subsistence harvest under section
101(b)(3) of the MMPA. In order to do so, the Secretary would be
responsible for demonstrating that such regulations are ``supported by
substantial evidence on the basis of the record as a whole.'' As stated
in the response to Comment 18, we do not believe that the subsistence
harvest poses an immediate threat to the southwest Alaska DPS;
therefore, regulation of the harvest is not warranted at this time.
Comment 20: Several other commenters expressed concern that listing
under the Act may result in the prohibition on export of authentic
Native handicrafts made from sea otters.
Our Response: Our regulations at 50 CFR 17.31 of the Act outline
prohibited activities, including import or export of listed species
from the United States. As we do not believe the current level of
subsistence harvest poses a threat to the southwest Alaska DPS, in
today's Federal Register, we proposed the promulgation of a special
rule under Section 4(d) of the Act that would align the provisions of
the Act relating to the creation, shipment, and sale of the authentic
native handicrafts and clothing by Alaska Natives with what is already
allowed under the MMPA. Export for commercial purposes is prohibited
under both the MMPA and the Act, and would not be authorized under the
proposed special rule.
[[Page 46377]]
Issue 6: Impacts of Listing
Comment 21: Several commenters expressed concern that listing under
the Act may result in additional regulation of commercial fisheries in
southwest Alaska. Other commenters expressed concern about the impacts
of listing on harbor and dock projects in the region.
Our Response: The best available scientific information indicates
that interactions between commercial fisheries and sea otters, either
in the form of competition for prey species or entanglement in gear, do
not pose an immediate threat to sea otters in southwest Alaska.
Information on fishery interactions is limited, however, and additional
observer programs directed at fisheries with the greatest potential for
entanglement of sea otters is recommended.
Harbor and dock projects that have a Federal nexus and that may
affect listed species require interagency consultation under Section 7
of the Act. Those projects that are likely to adversely affect the
species must undergo formal consultation, which may result in minor
changes to the project design to minimize the impact to sea otters.
Lastly, while economic impacts are considered when designating
critical habitat for a listed species, they do not factor into
decisions about listing.
Issue 7: Critical Habitat
Comment 22: Several commenters state that habitat protection is
important for the survival of sea otters in southwest Alaska. Other
commenters stated that it was unclear how critical habitat will be
designated. Yet another commenter stated that critical habitat should
not be broadly defined, and that shallow coves and lagoons may be
important for sea otters as refugia from predators.
Our Response: Although there is no evidence to suggest that loss of
habitat has been a contributing factor in the sea otter decline, we
agree that habitat protection may be an important factor in the
recovery of the population. However, the extent of critical habitat is
not yet determinable. The Service specifically requested input on this
subject during the public comment period, and we are currently
considering how best to delineate critical habitat for the southwest
Alaska DPS of the northern sea otter. Once we are able to determine the
geographic extent of critical habitat, it will be designated through a
separate rulemaking process that will include an opportunity for public
review and comment.
Comment 23: One peer reviewer and one commenter stated that if
killer whale predation is the cause of the sea otter decline, then the
true critical habitat for this DPS may actually be further offshore in
areas not inhabited by the otters themselves. That is, changes in
killer whale habitat may be responsible for increased predation of sea
otters.
Our Response: We find that designation of critical habitat for the
southwest Alaska DPS of the northern sea otter is not determinable at
this time because we are unable to identify the physical and biological
features essential to the conservation of this DPS. See Critical
Habitat. We will consider designating critical habitat for this species
later, as allowed under the Act when the Service considers critical
habitat ``not determinable'' at the time of listing.
Issue 8: Interagency Consultation and Recovery Planning
Comment 24: One reviewer stated that interagency consultation under
Section 7 of the Act will not be an effective means of enhancing the
sea otter population in southwest Alaska.
Our Response: The purpose of interagency consultation is to
determine if activities with a Federal nexus may affect listed species.
Although we cannot identify any human activities that have been
directly responsible for the sea otter decline, interagency
consultation will help minimize the impacts of future activities on the
recovery of the DPS.
Comment 25: One commenter stated that the Service should promptly
form a recovery team and begin the process of recovery planning.
Our Response: We agree that recovery planning should commence as
soon as possible, and have been working throughout the listing process
with potential members of a recovery team. We anticipate forming the
recovery team and beginning the process of recovery planning within the
first year following publication of this final rule.
Comment 26: Several commenters stated that, as there is no evidence
that human activities are directly responsible for the sea otter
decline, a recovery plan will not be effective. Similarly, several
other commenters stated that there are no human actions that can be
taken that would increase the sea otter population in southwest Alaska.
Our Response: We believe that it is premature to conclude that
there are no human actions that could be taken to conserve the sea
otter population in southwest Alaska. This issue will be more
appropriately addressed in the recovery planning process. Although
there is no evidence to suggest that human activities are directly
responsible for the decline, we also believe that the development of a
recovery plan will help identify potential future threats to the
southwest Alaska DPS of the northern sea otter. Protection from these
threats would become even more important should the population continue
to decline. For example, although there is no evidence to suggest that
oil spills have caused the sea otter decline, there may be areas of
high concentrations of sea otters that could benefit from additional
spill response planning and protection measures. The recent spill from
the M/V Selendang Ayu underscores the unpredictable, and potentially
catastrophic, effects of oil spills in southwest Alaska.
Comment 27: One commenter proposed that sea otters could be
translocated from southeast to southwest Alaska to help reverse the
population decline.
Our Response: As evidenced by the success of translocations to
southeast Alaska, Washington State, and British Columbia, Canada, this
technique has been effective at re-establishing sea otter populations
in areas where they had been extirpated by commercial fur harvests.
Specific measures to help conserve the sea otter population in
southwest Alaska will be considered during the recovery planning
process.
Comment 28: One commenter proposed that management authority for
sea otters should be transferred to the Alaska Department of Fish and
Game.
Our Response: The MMPA delegates authority for sea otters in U.S.
waters to the Secretary of the Interior. Sections 109(b) and 109(f) of
the MMPA outline the procedure for transfer of management authority
from Federal to State jurisdiction. Any transfer of authority must be
initiated by a request from the State, which has not occurred.
Issue 9: Research Needs
Comment 29: Several commenters stated that additional research is
needed, including studies into the cause of the decline, the genetic
structure of sea otter populations in Alaska, population surveys,
tagging and tracking individual otters, and fisheries observer
programs, prior to listing the population under the ESA.
Our Response: We fully agree that additional research is needed to
help determine the cause of the sea otter decline as well as identify
future threats to the southwest Alaska DPS. In April 2002 we convened a
workshop in Anchorage, Alaska, to review available information
regarding the sea otter
[[Page 46378]]
decline in southwest Alaska and develop recommendations for future
research. In April 2004, a second similar workshop was hosted by the
Alaska SeaLife Center in Seward, Alaska. We have continued to monitor
the population at several locations throughout southwest Alaska, and
have initiated several studies in conjunction with the U.S. Geological
Survey, Alaska SeaLife Center, and TASSC.
The need for additional research does not preclude us from listing
the DPS at this time, as the Act requires us to consider the best
scientific and commercial data available. Although some of these
studies are ongoing now, to postpone this listing action until
additional research has been completed would not improve the status of
the species, and would not be in keeping with the mandates of the Act.
Issue 10: The Listing Process
Comment 30: Several commenters stated that the Service did not
follow standard operating procedures and Secretarial Order 3225
regarding government-to-government consultation with Alaska Native
Tribes.
Our Response: As detailed in the introduction to this section of
the final rule, the Service actively engaged in consultation with
Alaska Native Tribes in southwest Alaska. From the time that we
developed plans to conduct the aerial survey of sea otters in the
Aleutians in January 2000 until publication of the proposed rule in
February 2004, the Service kept TASSC, a tribally authorized
organization, fully informed on this issue. The Service attended
multiple board meetings each year to present updated information on
survey plans and results, as well as progress on the development of the
proposed rule. In addition to board meetings, we provided TASSC with
monthly updates on these issues. Following publication of the proposed
rule, the Service actively solicited comments from 52 Alaska Native
Tribes within the range of the southwest Alaska DPS of the northern sea
otter. We received comments on the proposed rule from six tribal
councils, as well as TASSC and the Aleut Marine Mammal Commission, both
tribally-authorized Alaska Native Organizations.
Comment 31: Several commenters stated that the listing action was
not initiated by individuals, communities, or organizations within
southwest Alaska.
Our Response: It is not a requirement of the Act that listing
actions be initiated by residents of the area where the species,
subspecies, or DPS occurs. The listing action was initiated by the
Service, the Federal agency with management responsibility for sea
otters in U.S. waters. Biologists from the Marine Mammals Management
Office in Anchorage, Alaska, conducted the aerial surveys of sea otters
in 2000 and 2001 that determined the geographic extent and magnitude of
the decline. Based on the results of these surveys, the Service
designated sea otters in the Aleutians as a candidate species in August
2000. We later expanded candidate species designation to encompass the
range of the southwest Alaska DPS in June 2002.
Comment 32: The Service did not follow its own policy on the
recognition of distinct vertebrate population segments under the Act
(61 FR 4722).
Our Response: As detailed in our responses to earlier comments, the
Service followed the DPS policy. We first examined the discreteness of
the population segment in relation to the remainder of the species to
which it belongs. Next we determined the significance of the population
segment to the species to which it belongs, and finally, we evaluated
the population segment's conservation status in relation to the Act's
standards for listing. In doing so, we found that the sea otters in
southwest Alaska meet the definition of a DPS (see Distinct Vertebrate
Population Segment).
Comment 33: One commenter stated that the public comment period was
inconvenient.
Our Response: The typical public comment period for a proposed rule
to list a species under the Act is 60 days. Understanding that many
residents of southwest Alaska rely on subsistence and/or commercial
fishing, and that these activities are seasonal in nature, we
established a 120-day public comment period to give people more time to
review and comment on the proposed rule. We also scheduled the public
comment period to avoid conflict with summer fishing activities.
Peer Review
In accordance with our July 1, 1994, Interagency Cooperative Policy
for Peer Review in Act Activities (59 FR 34270), we solicited review
from five experts in the fields of ecology, conservation, genetics,
taxonomy, pathology, and management. Three of these experts have direct
experience with sea otters in Alaska, and the other two experts are
well-known marine mammal biologists. The purpose of such a review is to
ensure that listing decisions are based on scientifically sound data,
assumptions, and analyses, including input from appropriate experts.
Two reviewers sent us letters during the public comment period. Neither
reviewer expressed support or opposition to the listing of the
southwest Alaska DPS of the northern sea otter as threatened, but both
provided corrections on minor factual issues, interpretation of data,
and citations. Their information has been incorporated, as appropriate.
Distinct Vertebrate Population Segment
Pursuant to the Act, we must consider for listing any species,
subspecies, or, for vertebrates, any distinct population segment (DPS)
of these taxa if sufficient information indicates that such action may
be warranted. To interpret and implement the DPS provision of the Act
and Congressional guidance, the Service and the National Marine
Fisheries Service published, on December 21, 1994, a draft Policy
Regarding the Recognition of Distinct Vertebrate Population Segments
Under the Act and invited public comments on it (59 FR 65885). After
review of comments and further consideration, the Services adopted the
interagency policy as issued in draft form, and published it in the
Federal Register on February 7, 1996 (61 FR 4722). This policy
addresses the recognition of DPSs for potential listing actions. The
policy allows for more refined application of the Act that better
reflects the biological needs of the taxon being considered, and avoids
the inclusion of entities that do not require its protective measures.
Under our DPS policy, three elements are considered in a decision
regarding the status of a possible DPS as endangered or threatened
under the Act. These are applied similarly for additions to the list of
endangered and threatened species, reclassification, and removal from
the list. They are: (1) Discreteness of the population segment in
relation to the remainder of the taxon; (2) the significance of the
population segment to the taxon to which it belongs; and (3) the
population segment's conservation status in relation to the Act's
standards for listing (i.e., is the population segment, when treated as
if it were a species, endangered or threatened?). A systematic
application of the above elements is appropriate, with discreteness
criteria applied first, followed by significance analysis. Discreteness
refers to the isolation of a population from other members of the
species and we evaluate this based on specific criteria. We determine
significance by using the available scientific information to determine
the DPS's importance to the taxon to which it belongs. If we determine
that a population segment is discrete and significant, we then evaluate
it for
[[Page 46379]]
endangered or threatened status based on the Act's standards.
Discreteness
Under our Policy Regarding the Recognition of Distinct Vertebrate
Population Segments, 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 Act.
The focus of our DPS evaluation is the subspecies E. l. kenyoni,
which occurs from the west end of the Aleutian Islands in Alaska, to
the coast of the State of Washington (Wilson et al. 1991), as depicted
in Figure 1 of the Proposed Rule. To the west of the Aleutian Islands,
the sea otters in Russia are recognized as a separate subspecies, E. l.
lutris. Although sea otters in Russia are also delimited by an
international governmental boundary, differences in control of
exploitation, management of habitat, conservation status, and
regulatory mechanisms are not clear. Russia includes the sea otter as a
species that is recovering in its Red Data Book of the Russian
Federation (the Red Data Book is a listing of species afforded special
recognition or legal protection within Russia). Sea otters in Russia
are under jurisdiction of the Ministry of Natural Resources, and are
protected from all hunting, although poaching remains a concern. The
distance between the Near Islands in the Aleutians to the Commander
Islands in Russia is approximately 320 km (200 mi), and the amount of
interchange between the two subspecies is believed to be low because of
the long distance between island groups over deep water.
In the lower portion of Cook Inlet, a different type of barrier
exists in the form of an expanse of deep water. The distance across
lower Cook Inlet ranges from 50-90 km (31-56 miles). While sea otters
are physically capable of swimming these distances, the water depths of
up to 260 m (142 fathoms) and lack of food resources for sea otters in
deep water areas makes such movements across this open water area
unlikely. The degree to which this barrier limits sea otter movements
is not known with certainty.
Surveys conducted for sea otters and other species in the area of
lower Cook Inlet confirm the discontinuity of sea otters in this area.
In the summer of 1993, Agler et al. (1995) conducted boat-based surveys
of marine birds and mammals, including sea otters, in lower Cook Inlet.
During approximately 1,574 km (978 miles) of survey effort, only one
sea otter was observed in the center of the Inlet. More recently,
during an aerial survey of sea otters conducted in the summer of 2002,
no otters were observed on 324 km (201 miles) of transects flown across
the center of Cook Inlet (USGS in litt. 2002).
Information gathered incidental to surveys of other species also
indicates that sea otters rarely occur in the offshore areas of lower
Cook Inlet, further confirming the discontinuity of sea otters in this
area. The NMFS has conducted aerial surveys of beluga whales,
Delphinapterus leucas, in Cook Inlet since 1993. In addition to beluga
whales, observers recorded observations of other marine mammals,
including sea otters. During these surveys, which covered a combined
total of 11,583 km (7,197 miles) of systematic transects flown across
the inlet over several years, no sea otters were observed in the
deeper, offshore areas of Cook Inlet (Rugh et al. 2000). The NMFS also
conducted a marine mammal observer program during the Cook Inlet salmon
drift and set gillnet fisheries in 1999 and 2000 (Fadely and Merklein
2001). During this period with several thousand hours of observations,
no sea otters were recorded in the offshore areas of Cook Inlet. Given
the amount of survey effort that has been expended, the almost complete
lack of observations in deeper offshore waters suggests that there may
be only limited exchange of sea otters between the eastern and western
shores of lower Cook Inlet.
Sea otters in southwest and southcentral Alaska also differ
morphologically. Comparison of 10 skull characteristics between 26
adult sea otters from Amchitka Island and 42 sea otters from Prince
William Sound showed numerous statistically significant differences,
with the Amchitka otters being the larger of the two (Gorbics and
Bodkin 2001).
Genetic and morphological differences were part of the basis for
identification of sea otter population stocks under the MMPA (USFWS
2002a, USFWS 2002b, USFWS 2002c). The Service and NMFS have adopted the
methods of Dizon et al. (1992), who outlined four criteria for
consideration when identifying marine mammal population stocks: (1)
Distribution; (2) population response; (3) morphology; and (4)
genetics. Applying these criteria to the best available scientific
information, Gorbics and Bodkin (2001) identified three stocks of sea
otters in Alaska, the southwest, southcentral, and southeast stocks,
with ranges as depicted in Figure 5 of the Proposed Rule.
Within the range of the southwest Alaska stock of the northern sea
otter, we recognize that there are differences in the rates and
magnitude of population decline since the mid-1980s. Although there is
some evidence of additional genetic differentiation within the
southwest Alaska stock (Cronin et al. 2002), the best available
scientific information on taxonomy, genetics, and morphometrics does
not support identification of additional sea otter stocks at this time.
The stock assessment process outlined in Section 117 of the MMPA
includes oversight by Regional Scientific Review Groups (SRGs) composed
of non-Federal marine mammal experts. The information upon which the
Service based currently recognized stock structure was reviewed by the
Alaska Regional SRG, who concurred with the identification of three sea
otter stocks in Alaska. As both the identification of marine mammal
stocks under the MMPA and the discreteness evaluation of a DPS under
the Act are based upon similar criteria, we believe that the
appropriate geographic extent for this DPS corresponds to the entire
southwest Alaska stock, rather than any smaller area within the stock
boundary.
In summary, sea otters from the Aleutian Islands to lower western
Cook Inlet are a population that differs from other sea otters in
several respects. Sea otters to the west of the Aleutians are
geographically separated by an expanse of approximately 320 km of open
water and an international boundary, and are recognized as belonging to
a different taxon, the subspecies E. l. lutris. Within the taxon E. l.
kenyoni, there are physical barriers to movement across the upper and
the lower portions of Cook Inlet, and there are morphological and some
genetic differences between sea otters that correspond to the southwest
and southcentral Alaska stocks that we identified under the MMPA, with
Cook Inlet being the boundary separating these stocks. The geographic
separation between the southwest and southeast Alaska stocks is even
greater than between the southwest and southcentral Alaska stocks.
Based on our consideration of the best scientific information
available, we find
[[Page 46380]]
that the southwest Alaska population of the northern sea otter that
occurs from the Aleutian Islands to Cook Inlet, corresponding to the
southwest Alaska stock as identified by us previously under the MMPA
(Figure 5 of the Proposed Rule), is markedly separated from other
populations of the same taxon as a consequence of physical factors, and
there is genetic and morphological discontinuity that is evidence of
this separation. Therefore, the southwest Alaska population of the
northern sea otter meets the criterion of discreteness under our Policy
Regarding the Recognition of Distinct Vertebrate Population Segments.
Significance
If we determine a population segment is discrete, we next consider
available scientific evidence of its significance to the taxon to which
it belongs. Our policy states that this consideration may include, but
is not limited to, the following:
1. Persistence of the discrete population segment in an ecological
setting unusual or unique for the taxon,
2. Evidence that loss of the discrete population segment would
result in a significant gap in the range of the taxon,
3. Evidence that the discrete population segment represents the
only surviving natural occurrence of a taxon that may be more abundant
elsewhere as an introduced population outside its historic range, or
4. Evidence that the discrete population segment differs markedly
from other populations of the species in its genetic characteristics.
The sea otter population that corresponds to the southwest Alaska
stock contains over 60 percent of the current geographic range for the
subspecies E. l. kenyoni. Following protection from commercial
exploitation in 1911, sea otters recovered quickly in southwest Alaska,
which is a remote part of the State. In the mid-1980s, biologists
believed that 94 percent of the subspecies E. l. kenyoni, and 84
percent of the world population of E. lutris, existed in southwest
Alaska (Calkins and Schneider 1985). Loss of this population segment
would result in a significant gap of more than 2,500 km (1,553 mi.), in
both the current and historical range of the species, E. lutris. Loss
of this DPS would result in the loss of a ``major geographic area'' to
both the species and subspecies.
The range of the southwest Alaska DPS contains 6 of the 11 remnant
sea otter populations that survived the commercial fur harvests.
Descendants of only one of these remnant populations (Amchitka) have
been translocated beyond the boundaries of the DPS to southeast Alaska,
Washington State, and British Columbia, Canada. The genetic diversity
of the other 5 remnant populations within the southwest Alaska DPS
occurs nowhere else in the world. Loss of this DPS would therefore
result in a significant loss of genetic diversity of both the species
E. lutris and subspecies E. lustris kenyoni. The worldwide population
of sea otters underwent a genetic bottleneck as a result of commercial
fur harvests; additional loss of genetic diversity may reduce overall
fitness of both the species and subspecies.
Therefore, we find that the southwest Alaska population segment is
significant to the taxon to which it belongs because the loss of this
segment would result in a significant gap in the range and the segment
contains a significant amount of genetic diversity of the taxon.
Summary of Discreteness and Significance Evaluations
Based on the above consideration of the southwest Alaska population
of the northern sea otter's discreteness and its significance to the
remainder of the taxon, we find that it is a distinct population
segment. The population's discreteness is due to its separation from
other populations of the same taxon as a consequence of physical
factors, and there are morphological and genetic differences from the
remainder of the taxon that are evidence of this separation. The
population segment's significance to the remainder of the taxon is due
principally to the significant gap that its loss would represent in the
range of the taxon. In addition, this population segment represents a
considerable portion of the overall genetic variability of the species.
We refer to this population segment as the southwest Alaska DPS
throughout this final rule.
Conservation Status
Pursuant to the Act, we must consider for listing any species,
subspecies, or, for vertebrates, any distinct population segment of
these taxa, if there is sufficient information to indicate that such
action may be warranted. We have evaluated the conservation status of
the southwest Alaska DPS of the northern sea otter in order to make a
determination relative to whether it meets the Act's standards for
listing the DPS as endangered or threatened. Based on the definitions
provided in section 3 of the Act, endangered means the DPS is in danger
of extinction throughout all or a significant portion of its range, and
threatened means the DPS is likely to become endangered within the
foreseeable future throughout all or a significant portion of its
range.
Summary of Factors Affecting the Species
Section 4 of the Act and regulations (50 CFR part 424) promulgated
to implement the listing provisions of the Act set forth the procedures
for adding species to the Federal list. As defined in section 3 of the
Act, the term ``species'' includes any subspecies of fish or wildlife
or plants, and any distinct population segment of any species or
vertebrate fish or wildlife which interbreeds when mature. We may
determine a species to be an endangered or threatened species due to
one or more of the five factors described in section 4(a)(1) of the
Act. These factors, and their application to the southwest Alaska DPS
of the northern sea otter, are as follows:
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Habitat destruction or modification are not known to be major
factors in the decline of the southwest Alaska DPS of the northern sea
otter. At present, no curtailment of range has occurred, as sea otters
still persist throughout the range of the DPS, albeit at markedly
reduced densities. As there is no evidence to suggest that the decline
has abated, it is possible that additional population losses may occur
that would curtail the range of sea otters in southwest Alaska. In
particular, sea otters in the western and central Aleutian islands, and
Shumagin and Pavlof islands, have declined by an order of magnitude or
more, and recent survey data indicates the decline continues in these
areas. If this trend continues, the range of sea otters in the
southwest Alaska DPS may contract within the foreseeable future.
Human-induced habitat effects occur primarily in the form of
removal of some of the prey species used by sea otters as a result of
resource use such as commercial fishing, which occurs throughout
southwest Alaska. While there are some fisheries for benthic
invertebrates in southwest Alaska, there is little competition for prey
resources due to the limited overlap between the geographic
distribution of sea otters and fishing effort. In addition, the total
commercial catch of prey species used by sea otters is relatively small
(Funk 2003). In studies of sea otters in the Aleutians, there was no
evidence that sea otters are nutritionally stressed in that area, and
foraging behavior, measured as percent feeding success, has increased
during the 1990's (Estes et al. 1998).
[[Page 46381]]
Development of harbors and channels by dredging may affect sea
otter habitat on a local scale by disturbing the sea floor and
affecting benthic invertebrates that sea otters eat. There are
approximately 40 communities located within the range of the southwest
Alaska DPS. As harbor and dredging projects typically impact an area of
50 hectares or less, we consider the overall impact of these projects
on sea otter habitat to be negligible.
Catastrophic oil spills have the potential to adversely modify sea
otter habitat, and are discussed in detail under Factor E.
Considering the broad range of the southwest Alaska DPS of the
northern sea otter, along with the relatively minimal amount of human
habitation and activities in this region, destruction or modification
of habitat is not a threat to the continued existence of this DPS in
the foreseeable future. If current population trends continue, however,
the range of sea otters within the DPS may contract. Areas of higher
otter concentrations may be more susceptible to catastrophic events
such as oil spills, disease epidemics, and severe weather conditions
that could remove a significant portion of the remaining sea otter
population.
The most recent example of a catastrophic event occurred on
December 8, 2004, when the M/V Selendang Ayu, a 225-m (738-ft)
freighter lost power and ran aground near Spray Cape on Unalaska
Island. The vessel split apart, spilling approximately 40,000 of the
estimate 500,000 gallons of intermediate fuel oil 380 (IFO 380). It is
uncertain how many otters were in the vicinity at the time of the
spill, but as of January 31, 2005, two oiled otter carcassed had been
recovered by response workers. The full impacts of this vessel
grounding will likely not be known for several years. If a vessel of
this size were to run aground in one of the remaining areas of high sea
otter abundance, the potential exists for serious impacts to the
remaining population.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Following 170 years of commercial exploitation, sea otters were
protected in 1911 under the International Fur Seal Treaty, which
prohibited further hunting. In 1972, the MMPA established a moratorium
on the take of all marine mammals in U.S. waters. Section 101(b) of the
MMPA provides an exemption for Alaska Natives to take marine mammals
for subsistence purposes. Although the Native exemption was established
in 1972, appreciable numbers of sea otters were not harvested until the
mid-1980s (Simon-Jackson 1988). In October 1988, we initiated the
marine mammal Marking, Tagging, and Reporting Program (MTRP) to monitor
the harvest of sea otter, polar bear (Ursus maritimus), and Pacific
walrus (Odobenus rosmarus divergens) in Alaska (50 CFR 18.23(f)).
The majority of the reported sea otter harvest occurs in southeast
and southcentral Alaska. Information from the MTRP estimates that the
subsistence harvest has removed fewer than 1,400 sea otters from the
southwest Alaska DPS since 1989 (average = 85/year; range = 24 to 180/
year). The majority of this harvest occurred in the Kodiak archipelago,
where levels ranged from 0.4 to 1.3 percent of the estimated population
size, which is well below the estimated growth rate of the population
(Doroff et al. in prep.). Although the average harvest in Kodiak from
2001 to 2003 was 76 otters per year, recent survey results indicate
that the sea otter population was relatively stable over that time
period. Based on the geographic extent and magnitude of the decline, it
appears that the current levels of subsistence harvest do not pose an
immediate threat to the southwest Alaska DPS. The impact of the
subsistence harvest will continue to be evaluated to insure that the
level of harvest does not materially and negatively affect the DPS in
the future.
Scientific research on sea otters occurs primarily as aerial and
skiff surveys of abundance, and such surveys are conducted infrequently
(once every few years) and when they occur, they last for very short
durations of time. During the 1990s, 198 otters were captured and
released as part of health monitoring and radio telemetry studies at
Adak and Amchitka (T. Tinker, University of California at Santa Cruz,
in litt. 2003). In 2004, sea otters from the southwest Alaska DPS were
captured as part of a multi-agency health monitoring study. All of the
60 otters captured in this study were released back into the wild. All
future scientific research on the southwest Alaska DPS will require
permits under Section 10 of the Act. In addition, review of permit
applications will require the Service to consult pursuant to Section 7
of the Act. Based on the magnitude of the current decline and the
statutory permit review requirements, we do not believe that the impact
of surveys, or the impact of capture/release activities, will be a
significant threat in the immediate future.
Translocations of sea otters from southwest Alaska to other areas
also has occurred. These translocations took place from 1965 to 1972,
and involved removal of a total of just over 600 sea otters from
Amchitka Island (Jameson et al. 1982). Estes (1990) estimated that the
sea otter population at Amchitka Island remained essentially stable at
more than 5,000 otters between 1972 and 1986, and consequently there is
no evidence that removals for the translocation program have resulted
in overutilization.
As there is no commercial use of sea otters in the United States,
and recreational, scientific, and educational use have been regulated
under the MMPA of 1972, we do not expect these factors will increase in
the foreseeable future. Based on a review of historical harvest
patterns, we also do not expect the subsistence harvest to increase in
the foreseeable future.
C. Disease or Predation
Parasitic infection was identified as a cause of increased
mortality of sea otters at Amchitka Island in 1951 (Rausch 1953). These
highly pathogenic infestations were apparently the result of sea otters
foraging on fish, combined with a weakened body condition brought about
by nutritional stress. More recently, sea otters have been impacted by
parasitic infections resulting from the consumption of fish waste.
Necropsies of carcasses recovered in Orca Inlet, Prince William Sound
(which is not within the range of the southwest Alaska DPS), revealed
that some otters in these areas had developed parasitic infections and
fish bone impactions that contributed to their deaths (Ballachey et al.
2002, King et al. 2000). Measures such as heating and grinding waste
materials, or barging it further offshore, have proven successful at
eliminating these impacts. There is no evidence that the fish
processing operations are resulting in disease on any substantial scope
or scale for the southwest Alaska DPS of the northern sea otter.
The cause of the sea otter decline in the Aleutians has been
explored by reviewing available data on sea otter reproduction,
survival, distribution, habitat, and environmental contaminants. Estes
et al. (1998) concluded that the observed sea otter decline was most
likely the result of increased adult mortality. While disease,
pollution, and starvation may all influence sea otter mortality, no
evidence available at this time suggests these factors are
significantly contributing to the decline in the Aleutians. If the
declining population
[[Page 46382]]
trend continues and sea otters disappear from portions of the range of
the southwest Alaska DPS, however, the remaining otters that persist in
areas of higher concentration may be more vulnerable to disease
epidemics.
The weight of evidence of available information suggests that
predation by killer whales (Orcinus orca) may be the most likely cause
of the sea otter decline in the Aleutian Islands (Estes et al. 1998).
Data that support this hypothesis include: (1) A significant increase
in the number of killer whale attacks on sea otters during the 1990s,
(Hatfield et al. 1998); (2) the number of observed attacks fits
expectations from computer models of killer whale energetics; (3) the
scarcity of beachcast otter carcasses that would be expected if disease
or starvation were occurring; and (4) markedly lower mortality rates
between sea otters in a sheltered lagoon (where killer whales cannot
go) as compared to an adjacent exposed bay. Similar detailed studies
have not yet been conducted in other areas within the southwest Alaska
DPS, and the role of killer whale predation on sea otters outside of
the Aleutians is unknown.
Doroff et al. (2003) speculated that killer whale predation on sea
otters was density dependent, and that as of the April 2000 aerial
survey of the Aleutians, a steady state between predator and prey may
have been attained. Recent skiff survey results of Estes et al. (2005)
indicate that further sea otter declines occurred between 2000 and
2003, so it is not clear if a steady state between predator and prey
had been reached, or whether other factors were involved in the
continuing decline in the Aleutians.
The hypothesis that killer whales may be the principal cause of the
sea otter decline suggests that there may have been significant changes
in the Bering Sea ecosystem (Estes et al. 1998). For the past several
decades, harbor seals (Phoca vitulina) and Steller sea lions
(Eumetopias jubatus), the preferred prey species of transient, marine
mammal-eating killer whales, have been in decline throughout the
western north Pacific. In 1990, Steller sea lions were listed as
threatened under the Act (55 FR 49204). Their designation was later
revised to endangered in western Alaska, and threatened in eastern
Alaska, with the dividing line located at 144 degrees west longitude
(62 FR 24345). Estes et al. (1998) hypothesized that killer whales may
have responded to declines in their preferred prey species, harbor
seals and Steller sea lions, by broadening their prey base to include
sea otters. While the cause of sea lion and harbor seal declines is the
subject of much debate, it is possible that changes in composition and
abundance of forage fish as a result of climatic changes and/or
commercial fishing practices may be contributing factors.
It also recently has been hypothesized that the substantial
reduction of large whales from the North Pacific Ocean as a result of
post-World War II industrial whaling may be the ultimate cause of the
decline of several species of marine mammals in the north Pacific
(Springer et al. 2003). Killer whales are considered to be the foremost
natural predator of large whales. By the early 1970's, the biomass of
large whales had been reduced by 95 percent, a result attributed to
commercial harvesting. This reduction may have caused killer whales to
begin feeding more intensively on smaller coastal marine mammals such
as sea lions and harbor seals. As those species became increasingly
rare, the killer whales that preyed on them may have expanded their
diet to include the even smaller, and calorically inferior, sea otter.
The information supporting this theory is still under review. Although
the proximate cause of the current sea otter decline may be predation
by killer whales, the ultimate cause remains unknown. If these
hypotheses are correct, and prey selection by killer whales is closely
tied to the availability of other species, we would not expect this
threat to decrease in the future, perhaps until populations of other
prey species recover in numbers, or transient killer whale populations
decrease.
Besides killer whales, other predators on sea otters include white
sharks (Carcharodon carcharias), brown bears (Ursus arctos), and
coyotes (Canis latrans) (Riedman and Estes 1990). Carcasses of sea
otter pups have been observed in bald eagle (Haliaeetus leucocephalus)
nests (Sherrod et al. 1975). Although there is anecdotal information
regarding shark attacks on sea otters in Alaska, available data does
not suggest that the impact of sharks and predators other than killer
whales on the southwest Alaska DPS of the northern sea otter is
significant.
D. The Inadequacy of Existing Regulatory Mechanisms
The MMPA (16 U.S.C. 1361), enacted in 1972, is an existing
regulatory mechanism that protects sea otters. The MMPA placed a
moratorium on the taking of marine mammals in U.S. waters. Similar to
the definition of ``take'' under section 3 of the Act, ``take'' is
defined under the MMPA as ``harass, hunt, capture, or kill, or attempt
to harass, hunt, capture or kill'' (16 U.S.C. 1362). The MMPA does not
include provisions for restoration of depleted species or population
stocks, and does not provide measures for habitat protection.
The MMPA defines depleted as a species or population stock that is
below its optimum sustainable population (OSP), which is defined as
``the number of animals which will result in the maximum productivity
of the population or the species, keeping in mind the carrying capacity
of the habitat and the health of the ecosystem of which they form a
constituent element.'' By definition, a marine mammal species or stock
that is designated as ``threatened'' or ``endangered'' under the Act is
also classified as ``depleted'' under the MMPA. The converse is not
true, however, as a marine mammal species or stock may be designated as
depleted under the MMPA, but not be listed as threatened or endangered
under the Act.
Section 118 of the MMPA addresses the taking of marine mammals
incidental to commercial fishing operations. This section, which was
added to the MMPA in 1994, establishes a framework that authorizes the
incidental take of marine mammals during commercial fishing activities.
In addition, this section outlines mechanisms to monitor and reduce the
level of incidental take due to commercial fishing. Information from
monitoring programs administered by NMFS indicates that interactions
between sea otters and commercial fisheries result in less than one
instance of mortality or serious injury per year within the southwest
Alaska DPS and are, therefore, not a cause for concern at this time
(USFWS 2002a). An analysis of State-managed fisheries in southwest
Alaska reached a similar conclusion that there is little geographic
overlap between sea otters and commercial fishing activities (Funk
2003).
Although the MMPA contains provisions to regulate the take of sea
otters by Alaska Natives and to reduce the level of incidental take in
commercial fisheries, we do not believe that these impacts pose an
immediate threat to the southwest Alaska DPS. Therefore, the MMPA is
inadequate to prevent the continuing decline of sea o