Sex-specific and latitudinal variance in postnatal growth of the Subantarctic fur seal (Arctocephalus tropicalis)

1994 ◽  
Vol 72 (6) ◽  
pp. 1126-1133 ◽  
Author(s):  
Marthán N. Bester ◽  
Albert S. Van Jaarsveld
Keyword(s):  
Body Size ◽  
Growth Curves ◽  
Postnatal Growth ◽  
Polar Front ◽  
Parameter Estimates ◽  
Antarctic Polar Front ◽  
Fur Seals ◽  
Fur Seal ◽  
Gough Island ◽  
Arctocephalus Tropicalis

Parameter estimates reflecting age-specific growth of Subantarctic fur seals (Arctocephalus tropicalis) on Gough Island were fitted to three sigmoidal (Gompertz, logistic, and von Bertalanffy) growth curves. With a few exceptions, the logistic fit provided the best mathematical approximation of postnatal growth in fur seals from Gough Island, although all fits were significant. Standard length is a better reflection of age-specific changes in size than mass, which displayed considerable variance. Growth was characterized by marked sexual dimorphism. Interisland comparisons of body size from throughout the geographic range of the species suggested a latitudinal graded difference in adult body size, with the largest animals occurring at low-latitude Amsterdam Island and the smallest at Marion Island, which lies just north of the Antarctic Polar Front. These growth and body-size estimates can be used for monitoring the effects of population or ecosystem changes on fur seal productivity, but significant standardization of data collection procedures need to be introduced.

scholarly journals Ontogeny of body size and shape of Antarctic and subantarctic fur seals

2007 ◽  
Vol 85 (12) ◽  
pp. 1275-1285 ◽  
Author(s):  
Sebastián P. Luque ◽  
Edward H. Miller ◽  
John P.Y. Arnould ◽  
Magaly Chambellant ◽  
Christophe Guinet
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Morphological Traits ◽  
Body Shape ◽  
Size And Shape ◽  
Fur Seals ◽  
Fur Seal ◽  
Adult Body ◽  
Weaning Age ◽  
Lactation Duration

Pre- and post-weaning functional demands on body size and shape of mammals are often in conflict, especially in species where weaning involves a change of habitat. Compared with long lactations, brief lactations are expected to be associated with fast rates of development and attainment of adult traits. We describe allometry and growth for several morphological traits in two closely related fur seal species with large differences in lactation duration at a sympatric site. Longitudinal data were collected from Antarctic ( Arctocephalus gazella (Peters, 1875); 120 d lactation) and subantarctic ( Arctocephalus tropicalis (Gray, 1872); 300 d lactation) fur seals. Body mass was similar in neonates of both species, but A. gazella neonates were longer, less voluminous, and had larger foreflippers. The species were similar in rate of preweaning growth in body mass, but growth rates of linear variables were faster for A. gazella pups. Consequently, neonatal differences in body shape increased over lactation, and A. gazella pups approached adult body shape faster than did A. tropicalis pups. Our results indicate that preweaning growth is associated with significant changes in body shape, involving the acquisition of a longer, more slender body with larger foreflippers in A. gazella. These differences suggest that A. gazella pups are physically more mature at approximately 100 d of age (close to weaning age) than A. tropicalis pups of the same age.

Long term population changes of fur seals Arctocephalus gazella and Arctocephalus tropicalis on subantarctic (Crozet) and subtropical (St. Paul and Amsterdam) islands and their possible relationship to El Niño Southern Oscillation

1994 ◽  
Vol 6 (4) ◽  
pp. 473-478 ◽  
Author(s):  
C. Guinet ◽  
P. Jouventin ◽  
J-Y. Georges
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Enso Events ◽  
Fur Seals ◽  
Fur Seal ◽  
Arctocephalus Tropicalis

The population trend over the last decade for subantarctic fur seals (Arctocephalus tropicalis) on Amsterdam and St. Paul islands and on Possession Island (Crozet Archipelago) and Antarctic fur seals (A. gazella) on Possession Island are analysed. At Amsterdam Island, based on pup counts, the subantarctic fur seal population appears to have stabilized after a period of rapid growth. At Possession Island subantarctic fur seal and Antarctic fur seal, with respective annual growth rates of 19.2 and 17.4%, are reaching the maximum growth rate for the genus Arctocephalus. Annual pup censuses at Possession Island since 1978 indicate important variations from year to year with pup production for A. gazella significantly lower the year after an El Niño Southern Oscillation (ENSO) event, but with no such relationship for A. tropicalis. Several other long term demographic studies of seabirds and marine mammals at different breeding locations in the Southern Ocean indicate that the breeding success of several of these predators appears to be widely affected in years which appear to be related to the ENSO events. To clarify this, it is necessary to analyse in more detail the demographic data obtained for the different subantarctic and Antarctic locations where long term monitoring programmes are conducted.

Interannual variation in birth mass and postnatal growth rate of Juan Fernández fur seals

1998 ◽  
Vol 76 (5) ◽  
pp. 978-983 ◽  
Author(s):  
Hugo Ochoa-Acuña ◽  
John M Francis ◽  
Daryl J Boness
Keyword(s):  
Growth Rate ◽  
Body Mass ◽  
Growth Rates ◽  
Interannual Variation ◽  
Postnatal Growth ◽  
Male And Female ◽  
Fur Seals ◽  
Fur Seal ◽  
Attendance Pattern

The objectives of this study were to establish body mass at birth, postnatal growth rate, and the factors that influence these parameters for the Juan Fernández fur seal, Arctocephalus philippii. Females of this species have an unusual attendance pattern in which foraging trips and shore visits last, on average, 12.3 and 5.3 days, respectively. Pup mass was obtained from cohorts born during the reproductive seasons in 1988 through 1992. Birth masses of male and female pups were significantly different, averaging 6.1 and 5.5 kg, respectively (F = 13.2, P < 0.0003, n = 238). Birth masses also differed among cohorts, being lowest in 1992 and highest in 1990. During the first 2 months of life, male and female pups grew at the same rate (79 ± 61.5 g · day-1 (mean ± SD); F[1] = 0.03, P = 0.8562). Interannual differences in growth rate during the first month were significant (F[4] = 8.14, P < 0.0001), as was the interaction between month and year effects (F[2] = 6.81, P = 0.0012). Growth rates for the 1990 cohort were lower than those in all other years except 1992. Birth masses and postnatal growth rates of Juan Fernández fur seal pups are comparable to those of other otariid species.

Relationships between childhood growth parameters and adult blood pressure: the Fels Longitudinal Study

2016 ◽  
Vol 8 (1) ◽  
pp. 113-122 ◽  
Author(s):  
R. T. Sabo ◽  
A. Wang ◽  
Y. Deng ◽  
C. S. Sabo ◽  
S. S. Sun
Keyword(s):  
Blood Pressure ◽  
Body Size ◽  
Longitudinal Study ◽  
Cardiovascular Health ◽  
Growth Parameters ◽  
Growth Curves ◽  
Parameter Estimates ◽  
Childhood Growth ◽  
Adiposity Rebound ◽  
And Gender

Previous research has shown that childhood body size is associated with blood pressure in adulthood, and that early and rapid growth rates are correlated with adverse cardiovascular outcomes. Our objectives are to estimate associations between childhood body size growth parameters and adult blood pressure, and to examine the effect of early attainment of critical growth milestones on adult blood pressure, relative to normal or late attainment. Lifetime height and body mass index (BMI) measurements in childhood, and systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements in adulthood are taken from participants in the Fels Longitudinal Study. Childhood growth curves are estimated separately for stature and BMI using the Preece–Baines and third-degree polynomial models, respectively. Associations between the resulting parameter estimates and adult blood pressure are then examined using linear mixed models. Our findings show that the ages of achievement of the stature-based growth onset and peak velocity, as well as the age of achievement of the BMI-based adiposity rebound, are negatively associated with adult blood pressure, implying that early height or BMI growth can lead to increased blood pressure in adulthood. There were subtle differences in these relationships based on age and gender, and also between SBP and DBP. These results expand on the existing literature, showing that not only childhood body size, but also the timing of childhood growth can have a deleterious effect on adult cardiovascular health.

scholarly journals A memory like a female Fur Seal: long-lasting recognition of pup's voice by mothers

2004 ◽  
Vol 76 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Nicolas Mathevon ◽  
Isabelle Charrier ◽  
Thierry Aubin
Keyword(s):  
Field Experiments ◽  
Individual Characteristics ◽  
Lactation Period ◽  
Acoustic Characteristics ◽  
Call Recognition ◽  
Fur Seals ◽  
Fur Seal ◽  
Vocal Recognition ◽  
Modulation Pattern ◽  
Arctocephalus Tropicalis

In colonial mammals like fur seals, mutual vocal recognition between mothers and their pup is of primary importance for breeding success. Females alternate feeding sea-trips with suckling periods on land, and when coming back from the ocean, they have to vocally find their offspring among numerous similar-looking pups. Young fur seals emit a 'mother-attraction call' that presents individual characteristics. In this paper, we review the perceptual process of pup's call recognition by Subantarctic Fur Seal Arctocephalus tropicalis mothers. To identify their progeny, females rely on the frequency modulation pattern and spectral features of this call. As the acoustic characteristics of a pup's call change throughout the lactation period due to the growing process, mothers have thus to refine their memorization of their pup's voice. Field experiments show that female Fur Seals are able to retain all the successive versions of their pup's call.

The foraging ecology of two sympatric fur seal species, Arctocephalus gazella and Arctocephalus tropicalis, at Macquarie Island during the austral summer

2002 ◽  
Vol 53 (7) ◽  
pp. 1071 ◽  
Author(s):  
S. A. Robinson ◽  
S. G. Goldsworthy ◽  
J. van den Hoff ◽  
M. A. Hindell
Keyword(s):  
Foraging Behaviour ◽  
Foraging Ecology ◽  
Austral Summer ◽  
Sympatric Species ◽  
Arctocephalus Gazella ◽  
Macquarie Island ◽  
Fur Seals ◽  
Fur Seal ◽  
Marine Environmental ◽  
Arctocephalus Tropicalis

Antarctic Arctocephalus gazella and subantarctic Arctocephalus tropicalis fur seals breed sympatrically at Macquarie Island. The two species have different lactation strategies, the former rearing its pup in 4 months and the latter taking 10 months. The diet and at-sea foraging behaviour of these sympatric species was compared during the austral summer period when their pup rearing period overlapped. The prey of the two fur seal species was very similar, with fish dominating the diet. The myctophid, Electrona subaspera, was the main prey item (93.9%) in all months of the study. There were no major differences in the diving behaviour between species. Both species foraged north of the island parallel to the Macquarie Ridge. Foraging activity was concentrated at two sites: (i) within 30�km north of the island; and (ii) at 60 km north. Most locations for overnight foraging trips were within 10 km of the colonies. The different lactation strategies of A. gazella and A. tropicalis allowed for flexibility in foraging behaviour. At Macquarie Island, the local marine environmental conditions have resulted in similar foraging behaviour for both species.

Geographic variation in skull characters of fur seals and sea lions (family Otariidae)

2002 ◽  
Vol 50 (4) ◽  
pp. 415 ◽  
Author(s):  
S. Brunner ◽  
P. D. Shaughnessy ◽  
M. M. Bryden
Keyword(s):  
South Africa ◽  
Geographic Variation ◽  
South African ◽  
West Coast ◽  
South Australia ◽  
Sea Lions ◽  
Fur Seals ◽  
Fur Seal ◽  
Condylobasal Length ◽  
Gough Island

Geographic variation was observed in skulls of several otariid species, with a general change in size corresponding with a change in latitude and primary productivity. The largest specimens were from cool temperate localities, conforming mostly to Rensch's rule. Skulls of Australian sea lions from Western Australia were generally smaller in condylobasal length, but were more robust than those from South Australia. The subantarctic fur seal did not conform to Bergmann's rule: skulls from Amsterdam Island (37�55´S) were largest, those from Gough Island (40�20´S) intermediate and those from Marion Island (46�55´S) the smallest. For both sexes, skulls of southern sea lions from the Falkland Islands were smaller than their equivalents from mainland South America. Similarly, skulls of South African fur seals from south-east South Africa appeared smaller than those from the west coast of South Africa and Namibia; skulls from Namibia grouped separately from those of south-east and west coast, South Africa. We postulate that the Otariidae are in the process of species divergence, much of which may be driven by local factors, particularly latitude and resources.

Fetal growth of northern fur seals: life-history strategy and sources of variation

1991 ◽  
Vol 69 (10) ◽  
pp. 2608-2617 ◽  
Author(s):  
Andrew W. Trites
Keyword(s):  
Specific Growth ◽  
Research Effort ◽  
Life History Strategy ◽  
Growth Curves ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Fur Seal ◽  
History Of ◽  
Sources Of Variation ◽  
Fetal Size

Sex-specific growth curves are described for northern fur seal fetuses, Callorhinus ursinus. The relationships between body length, body mass, and gestational age are derived by regression analysis based on 7000 fetuses collected during 1958–1974 as part of a joint Canadian–American pelagic research effort. Male fetuses grow faster and larger than female fetuses. Length approaches an asymptote with time, but the increase in fetal mass appears exponential until parturition. The size of the fetus is influenced by the age, size, and reproductive history of the mother. Primiparous females produce smaller pups than multiparous females. This difference in fetal size is presumably due to physiological changes associated with having been previously pregnant and is not explained merely by differences in the size and age of the different parities. Older and larger females produce progressively larger fetuses until reaching their reproductive prime at about the age of 10–11 years. Adult females continue to grow beyond this age, but there is a senescent decline in the length and mass of the young they carry. There is no indication that the sex ratio differs from unity either between months, across years, or between mothers of different ages and parities.

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