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Публикации
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17th BIENNIAL CONFERENCE ON THE BIOLOGY OF MARINE MAMMALS -
Cape Town, 29 November – 3 December 2007
О конференции
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Olfaction of abiotic objects and the social environment in
Steller Sea Lion's (Eumetopias jubatus) rookery life
Olfaction is one of the most important senses for the sustentation
of social structure in populations of Steller sea lions (SSL).
SSL receiving information regarding the surrounding social
environment as well as to detect attributes about the surrounding
abiotic objects. To understand the development of olfaction
and its role in the social life of different sexes and age
classes of SSL in connection with their harem was the aim of
our research. The observations were conducted on Medny Island
(Commander Islands) during the summers of 2005/06. During the
two seasons of study 2564 olfactory contacts were registered
(652-muzzle of understratum of rookery, 15- olfactory contacts
with Northern fur seals and 1872-olfactory contacts with the
conspecifics). Besides these mentioned olfactory contacts,
SSL often were also observed smelling the air of the rookery.
Unfortunately, we were unable to estimate the quantity of this
behavior, but it seems likely that general olfaction of wind
contents influences SSL behavior very much. During the reproductive
period the smell duration of abiotic objects averaged 1.5s
(n=338; min=1; max=10), while the average duration of interspecific
olfactory contact was 2.8s (n=913, min=1, max=45). Our observations
demonstrate that SSL spend more time on olfactory contacts
with conspecifics than with abiotic things. At the time immediately
after leaving the water SSL devote most of their olfactory
energies toward the understratum of rookery, and only then
continue to move onto the rookery. Olfaction of abiotic objects
borrows approximate ? of all SSL`s muzzle. Adult females smell
the rookery`s understratum more often than males and other
age classes of both sexes of SSL, however this does not appear
to depend on whether the female gave birth that season or not.
Various rookery smells are very informative for SSL, but in
a reproductive gathering, intimate contact with conspecifics
seems the most important
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Reproductive characteristics and survival of Steller sea
lions (Eumetopias jubatus) females on Kozlova cape
rookery (Eastern Kamchatka, Russia)
Kozlova Cape (Kamchatka, Russia) is the site of the only existing
Steller sea lion rookery along Eastern Kamchatka. Observations
of branded Steller sea lions were conducted using a Remote
Video Monitoring System during June-July 2001 – 2006. Average
annual pup production on Kozlova Cape rookery during this period
was 90.2. A total of 299 sea lion pups of both sexes were branded
on Kozlova Cape rookery during 7 branding trips over 9 years.
Reproductive patterns and survival of 96 females branded at
Kozlova cape as pups in 1996, 1997,1998 and 1999 were analyzed
based on resighting data. No females less than 4 years old
were observed giving birth on Kozlova Cape rookery. Two (4.2%)
females of the 96 that were branded, gave birth every year
during the observation period; the rest had a resting period
of 1 or 2 years. Ninety two percent of the females returned
to their rookery every year during the 6 years of observations,
either to haul out and rest or to produce pups and breed. A
total of 15.6% of branded females nursed yearlings in years
they did not produce pups. All branded females from the 1996,
1997, 1998 cohorts gave birth at least once before reaching
age 8, but 33.3% of the branded females from the 1999 cohort
did not produce any pups up to age 8. Cormack-Jolly-Seber (CJS)
modeling showed that we did not observe a cohort effect in
apparent survival or resight probability. The age specific
apparent survival rates for Steller sea lions on Kozlova Cape
are consistent with previously reported values both for cumulative
(York, 1994) and annual survival (ibid, Holmes and York, 2004).
The cumulative survival to age 5 observed on Kozlova Cape is
low, consistent with the lower juvenile survival rates described
in York (1994).
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New western gray whale (Eschrichtius
robustus) feeding area offshore Eastern Kamchatka, Russia
Vertyankin, Vladimir
V.; Vladimirov, Valeriy A.; Tyurneva, Olga Yu.; Yakovlev, Yuriy
M.; Burkanov, Vladimir N.
The western Pacific
gray whale populations (WGWP), one of the most critically endangered
among large whale ones (assessed at around 120 individuals),
has been observed to feed in a limited coastal region of northeastern
Sakhalin Island, Russia and this area is considered their only
foraging range. However, about 20-25 gray whales (GW) are observed
recently to feed annually in June-December in eastern Kamchatka
coastal waters. The majority of them is located in Ol`ga Bay
(up to 15 individuals), and also in Vestnik Bay and near Nalycheva
Cape. It has been hypothesized that they may belong to WGWP.
In order to test this supposition, photos of 12 GWs taken in
Ol`ga Bay and 1 GW taken in Vestnil Bay in 2006, as well as photos
of 3 GWs taken near Nalycheva Cape in 2004 were compared to the
Russian photo-identification catalog of 147 GWs recorded in the
waters off northeastern Sakhalin in 2002-2006. As a result it
has become apparent that 6 of 16 Kamchatka`s GWs (37.5%) were
also recorded offshore Sakhalin Island. Two GWs photographed
off Kamchatka in August 2006, were observed off Sakhalin, nearly
1000 km away, 50 and 39 days later, demonstrating that the animals
are quite capable of moving between the eastern Kamchatka and
Sakhalin feeding areas in the course of a single season. Interestingly,
two of four gray whales photographed in Ol`ga Bay on August 22,
2006 and identified in the catalogue (50%) were calves born in
2003 and 2004 that had not been recorded off Sakhalin Island
since they were first observed. The results obtained indicate
that bays on the east coast of the Kamchatka Peninsula can legitimately
be considered a second feeding location for a part of WGWP. More
work is clearly needed to understand its full feeding range.
||abstract||poster||presentation||
Spatial use by Steller sea lions on Dolgaya
Rock rookery in the Kuril Islands, Russia
Steller sea lions
reproduce at traditional rookeries on which territorial relationships
are established and necessitated in part by the need to optimize
space usage on rookeries. The knowledge of the features and patterns
of spatial use is important in understanding reproduction. Results
indicate that the minimal distance between bulls remains stable
both from year to year and during each years mating period (x=9
m., s.d.=4 m.). However, the minimal distance between females
was observed to change through the breeding season. During the
day of pup birth for each female the average distance to the
next female averaged 7 m (s.d.=3). Interestingly, during the
days following pup birth these distances began to decrease until
the day of copulation, when the distance separating females was
averaged to be 4 m (s.d.=2). The time period between giving birth
and copulation on Dolgaya Rock averaged 12 days (s.d.=4). During
this time, females usually moved within 2 m (s.d.=3) of their
first observed location for each day, while the geometrical center
of the spatial displacements during the days shifted on average
about 1 m of that from the previous day. In total, females shifted
9-10 m from the place of pup birth to the location of copulation.
Additionally, this critical distance is very similar to the minimal
distance estimated between bulls. We observed that in only 29%
of recorded cases did females mate with the male on whose territory
she gave birth. Females returning to the rookery to reproduce
displaced on average 11 meters (s.d.=7) from the precise location
of the previous year`s birth. However, these displacements are
limited spatially, and occur typically within a 6 m radius (s.d.=3).
According to our reckoning, mobility of females, is a very important
factor determining mating behavior of sea lions.
||abstract||poster||presentation||
Overview of abundance and trends of northern
fur seal (Callorhinus ursinus) in Commander Islands, 1958-2006,
caveats and conclusions
The northern
fur seal population in the Commander Islands has grown from approximately
38,000 pups in the late 1950s to the 20th century maximum level
of 75,000 pups in the mid-1970’s, at a rate of 2.8%. Since that
time the population has remained stable producing between 65,000
and 75,000 pups annually. We reviewed and interpreted old data
files to summarize the Commander Island fur seals counts during
this period. Although pup counts began to decrease in the late
1980s, a high variance in the pup counts and increasing numbers
of bachelor males on the rookery following the cessation of the
commercial harvest suggested that the population was stable or
even increasing during that period. The retirement of experienced
scientists and reduced funding contributed to poor data collection
and the interpretation of the system. During several years (1997,
1999, 2000, 2004 and 2005) the reliable method of counting pups
from land was replaced by extrapolations based on the maximum
number of females counted on rookeries in the middle of July.
An August, 2006 land count conducted on all rookeries in the
Commander Islands totaled 59,805 pups (55,972 alive and 3,833
dead). We used the land counts of pups, accounted for the general
distribution and abundance of non-pup fur seals throughout the
Commander Islands and concluded that the population of northern
fur seals in the Commander Islands slightly decreased between
the late 1980’s and mid 1990’s, but has remained relatively stable
to the present and produces approximately 60,000 pups annually.
||abstract||poster||presentation|| Northern fur seal (Callorhinus ursinus)
pup production in the Kuril Islands, 2005-2006
Historically,
northern fur seals were widely distributed in the Kuril Islands
across 9-10 rookeries. Uncontrolled harvest in the 19th century
eradicated the population and fur seals were considered extinct
there until two small rookeries were discovered in 1955-56. This
first survey counted 800-900 seals on Khitraya Rock (Srednego
Islands complex) and 2,000 seals on Fur Seal Rock (Lovushki Islands
complex). Regular surveys started in 1962 when approximately
1000 pups were counted on Lovushki and only 2 on Srednego. Pup
production grew rapidly between 1962-1977 (19.9% annual increase).
The population stabilized around 1978 and the pup production
trend from 1978-1988 became slightly negative (-0.8%). Surveys
ceased in 1988 but were restarted with similar methods in 2005.
Spook counts were conducted between July 31 and August 14 in
2005 and August 11-16 in 2006. At Lovushki, we counted 11,248
(±268) live and 611 dead pups in 2005 and 12,180 (±280) live
and 840 dead in 2006 (+8.3%). At Srednego we counted 17,544 (±335)
live and 789 dead pups in 2005 and 12,985 (±285) live and 1,085
dead pups in 2006 (-25.6%). Total pup production in the Kuril
Islands was 30,192 in 2005 and 27,090 in 2006. High inter-annual
variation at Srednego was probably because surveys were conducted
later than was optimal and pups were old enough to swim. Pup
production has increased 82.4% since 1988 (+3.8% annually) and
is now comparable to the Tuleny (Robben) Island population. Total
abundance of fur seals in the Kuril Islands currently exceeds
100,000 individuals.
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Assessing the effects of nutritional
stress on lactating female Steller sea lions (Eumetopias jubatus)
and their pups in temporary captivity
Abstract-Steller
sea lion (SSL) populations in Alaska and Russia have declined
dramatically over the last 30 years. Although nutritional stress
has been implicated in these declines, the mechanisms linking
foraging success to reproductive success are unclear. We conducted
this study to explore the feasibility of capturing and holding
mother/pup pairs in temporary captivity to determine how reduced
energy intake affects the lactating female’s ability to meet
energy requirements of a growing pup and future reproduction.
In July 2005, three mother/pup pairs were captured on Lovushki
Island (Kuril Islands) where SSL populations have been increasing
for 15 years. Six free-ranging adult female SSLs were sampled
on Lovushki for comparison. The three mother/pup pairs were held
at a temporary facility on Paramushir Island for 34 days. Females
were fed a diet of herring. All 3 adults lost mass with a mean
daily percent mass loss of 0.75, 0.30, and 0.16%. Pups nursed
consistently throughout the study period and displayed an increase
in mass (average daily gain of 0.14 to 0.36 kg d-1) correlated
to the condition of their mothers. All blood chemistry parameters
except blood urea nitrogen (BUN) were unexceptional. BUN levels
decreased over time demonstrating the typical protein-sparing
response of a fasting-adapted animal exposed to negative energy
balance (NEB). Pup BUN values were within the normal reported
range. Despite inadequate daily food consumption and reduction
in body mass, the adults were able to compensate for NEB and
maintain milk gross energy contents of 10.63 to 13.57 kJ g-1
wet weight throughout the study period, which is comparable to
gross energy values for free-ranging SSLs. The adult in the poorest
body condition was observed giving birth one year later, suggesting
that SSLs are capable of buffering short-term NEB with little
disruption of current and future reproductive success.
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