Age structure, growth, and demographic parameters in breeding-age female subantarctic fur seals, Arctocephalus tropicalis

2004 ◽  
Vol 82 (7) ◽  
pp. 1043-1050 ◽  
Author(s):  
Willy Dabin ◽  
Gwénaël Beauplet ◽  
Enrique A Crespo ◽  
Christophe Guinet
Keyword(s):  
Age Distribution ◽  
Reproductive Rate ◽  
Reproductive Period ◽  
Demographic Parameters ◽  
Island Population ◽  
Female Population ◽  
Regulatory Processes ◽  
Fur Seals ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

Age distribution was estimated for 108 breeding-age female subantarctic fur seals, Arctocephalus tropicalis (Gray, 1872), sampled during the 1999–2000 breeding season on Amsterdam Island, southern Indian Ocean. The growth features were described and demographic parameters assessed from transversal life tables constructed for this female population. The breeding females had a longer mean body length than was observed for other breeding populations of the same species. These females also showed a later start to reproduction (6 years old), a lower overall age-specific reproductive rate (R6–16 = 48.0%), and a lower survival in older age classes (>13 years). Females reproduced up to a maximum age of 16 years, with none older than 19 years observed in the colony, suggesting an apparent senescence in the population. This consequently reduced the theoretical reproductive period of the females, which has led to a lower number of reproductive outputs per individual (i.e., 3.65 weaned pups per female throughout its reproductive life). Although such differences between islands may be related to genotypic traits, these results are consistent with low food availability and suggest that density-dependent regulatory processes operate on the Amsterdam Island population.

Milking Strategy in Subantarctic Fur Seals Arctocephalus tropicalis Breeding on Amsterdam Island: Evidence from Changes in Milk Composition

2001 ◽  
Vol 74 (4) ◽  
pp. 548-559 ◽  
Author(s):  
Jean‐Yves Georges ◽  
René Groscolas ◽  
Christophe Guinet ◽  
Jean‐Patrice Robin
Keyword(s):  
Milk Composition ◽  
Fur Seals ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

scholarly journals Resistance and tolerance of ten carrot cultivars to the hawthorn-carrot aphid, Dysaphis crataegi Kalt., in Poland

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247978
Author(s):  
Maria Pobożniak ◽  
Małgorzata Gaborska ◽  
Tomasz Wójtowicz
Keyword(s):  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Natural Increase ◽  
Reproductive Period ◽  
Field Resistance ◽  
Intrinsic Rate Of Increase ◽  
Demographic Parameters ◽  
Reproduction Rate ◽  
Net Reproductive Rate ◽  
Rate Of Increase

Damage caused to cultivated carrots by the hawthorn-carrot aphid, Dysaphis crataegi Kalt. (Hemiptera: Aphididae) is one of the factors limiting carrot production in Poland. Planting resistant and tolerant cultivars could reduce yield losses due to the damage caused by this pest. This study was conducted to evaluate the resistance and/or tolerance of 10 carrot genotypes to hawthorn-carrot aphid. Their field resistance was determined under field conditions based on five indicators, namely, mean number of alates (migrants) per plant and mean percentage of plants colonized by them, mean seasonal number of aphids per plant, mean number of aphids per plant and mean percentage of infested plants at peak abundance. Antibiosis experiments were conducted under laboratory conditions and pre-reproductive, reproductive time, fertility, and demographic parameters, represented by the net reproduction rate (Ro), intrinsic rate of increase (rm) and mean generation time (T), were calculated. Five cultivars, Afro F1, Nipomo F1, Samba F1, White Satin F1, and Yellowstone showed field resistance. Antibiosis experiments revealed significant differences among the carrot cultivars in the length of the reproductive period, female fecundity in the time equal to the pre-reproduction time, and total progeny of hawthorn-carrot aphid. The intrinsic rate of natural increase (rm) for apterous aphids varied significantly, ranging between 0.181 (Nipomo F1) and 0.343 females/female/day (White Satin F1). Additionally, the estimated net reproductive rate (R0) was the lowest on Nipomo F1, and this genotype was determined to be resistant. Our results suggest that a very high density of trichomes on the leaf petioles (71.94 trichomes/cm2) could adversely affect the feeding, bionomy, and demographic parameters of hawthorn-carrot aphid on the cultivar Nipomo F1. In addition, Napa F1 and Kongo F1 demonstrated high tolerance. Considering all the results collectively, four genotypes, Afro F1, Kongo F1, Napa F1 and Nipomo F1, were relatively resistant/tolerant to the hawthorn-carrot aphid.

Subantarctic fur seals Arctocephalus tropicalis at Heard Island

Polar Biology ◽  
1989 ◽  
Vol 9 (5) ◽  
pp. 337-339 ◽  
Author(s):  
S. D. Goldsworthy ◽  
P. D. Shaughnessy
Keyword(s):  
Fur Seals ◽  
Heard Island ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

Myeloid and histiocytic sarcomas in subantarctic fur seals Arctocephalus tropicalis, Brazil

2021 ◽  
Author(s):  
L Reisfeld ◽  
NCCA Fernandes ◽  
A Sarmiento ◽  
P Canedo ◽  
F Salvagni ◽  
...  
Keyword(s):  
Fur Seals ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

scholarly journals Characterization of the faecal bacterial community of wild young South American (Arctocephalus australis) and Subantarctic fur seals (Arctocephalus tropicalis)

2016 ◽  
Vol 92 (3) ◽  
pp. fiw029 ◽  
Author(s):  
Aline Weber Medeiros ◽  
Adriana Giongo ◽  
Fernanda P. Valdez ◽  
Derek Blaese de Amorin ◽  
Maurício Tavares ◽  
...  
Keyword(s):  
Bacterial Community ◽  
South American ◽  
Fur Seals ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

Long-term evaluation of pup growth and preweaning survival rates in subantarctic fur seals, Arctocephalus tropicalis, on Amsterdam Island

2003 ◽  
Vol 81 (7) ◽  
pp. 1222-1232 ◽  
Author(s):  
Magaly Chambellant ◽  
Gwénaël Beauplet ◽  
Christophe Guinet ◽  
Jean-Yves Georges
Keyword(s):  
Growth Rate ◽  
Food Availability ◽  
Survival Rates ◽  
Birth Date ◽  
Growth And Survival ◽  
Fur Seals ◽  
Pup Growth ◽  
Sst Gradient ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

This study is the first to investigate pup preweaning growth and survival rates over seven consecutive breeding seasons in subantarctic fur seals, Arctocephalus tropicalis, on Amsterdam Island, southern Indian Ocean. Growth and survival were studied in relation to year and pup sex, birth date, birth mass, and growth rate at 60 days of age. The pup growth rate decreased over the 7-year study period and was the lowest ever found in otariids, which suggests that lactating females experience constant low food availability. Male and female pups grew and survived at similar rates. Pups that were heavier at birth grew faster and exhibited better early survival (i.e., the first 2 months of life) than pups that were lighter at birth. However, no such relationship was detected for late survival (i.e., from 2 months to weaning) in this long-lactating species. No relationship was found between pup growth rate, pup survival rate, and sea-surface temperature (SST) gradient during the study period, especially during the later years of good trophic conditions (i.e., a high SST gradient). Such dissociations suggest that variation in food availability may not be the only factor influencing pup performance until weaning. We therefore propose that the subantarctic fur seal population is reaching its carrying capacity and that a density-dependent effect is occurring on Amsterdam Island.

scholarly journals The Influence of the Age of the Mother and Associated Factors on the Mortality Rates in Childbearing

1929 ◽  
Vol 29 (2) ◽  
pp. 160-190 ◽  
Author(s):  
Peter L. McKinlay
Keyword(s):  
Young Women ◽  
Death Rate ◽  
Causes Of Death ◽  
Age Distribution ◽  
Mortality Rates ◽  
Reproductive Period ◽  
Married Women ◽  
Young Mothers ◽  
Female Population ◽  
Reproductive Life

In the present paper an attempt has been made to devise a method of determining mortality rates at ages from causes of death associated with childbearing. The sources of possible fallacy in this procedure have been discussed, and it is probable that the results found will represent fairly accurately the true course of mortality in this country.From all causes of death in childbearing, mortality follows this course: beginning with a high value in the age group 15–20, the rate drops to a minimum in the second quinquennium of reproductive life and thereafter gradually increases with age.The main components of the death rate exhibit a similar age distribution, but other less important causes of death show an uninterrupted increase with age from the commencement of the reproductive period.Eclampsia is much more common in young women, but this may be entirely due to the greater proportion of primiparae at these young ages. Estimated in terms of first births the death rate increases rapidly and steadily with age, subject to a small exception in the first quinquennium which may possibly be a consequence of unfavourable marital selection at that age.The high puerperal mortality of young mothers cannot wholly be accounted for by the excessive dangers of primiparity. Evidence has, however, been submitted that these young women are, on the average, a less healthy sample of the total female population at that age and that, apart from primiparity and adverse selection, the death rate from childbed causes probably follows the same law of mortality as of women in general from all other causes of death.There has been within recent years a decline of nearly 50 per cent, in the puerperal mortality in young mothers of 15–20 and a smaller decrease in the second quinquennium of reproductive life; but there is no evidence of any improvement at later ages. These phenomena have been brought into relation with the change which has taken place in the death rate from all other causes in married women at these ages. The youngest group of married women, relative to unmarried of the same age, were in the more recent period studied in a much more favourable position with regard to their mortality from causes other than those connected with childbearing than they had been formerly. No corresponding improvement has taken place in the relative mortalities from all other causes in older women within the childbearing ages.These results suggest that the general health of the mother is a factor of great importance in determining the height of the mortality rate in pregnancy.

Records of subantarctic fur seals Arctocephalus tropicalis in Australia.

1992 ◽  
Vol 15 (1) ◽  
pp. 135
Author(s):  
N.J. Gales ◽  
D.K. Coughran ◽  
L.F. Queale
Keyword(s):  
Fur Seals ◽  
Subantarctic Fur Seals ◽  
Arctocephalus Tropicalis

NA

A Fur Seal Population Model Based on Age Structure Data

1990 ◽  
Vol 47 (1) ◽  
pp. 122-127 ◽  
Author(s):  
L. L. Eberhardt
Keyword(s):  
Adult Female ◽  
Structure Data ◽  
Age Structure ◽  
Survival Rates ◽  
Reproductive Rate ◽  
Chi Square ◽  
Female Population ◽  
Fur Seals ◽  
Female Survival ◽  
Major Period

About 16 000 female fur seals from the Pribilof Islands population were aged in pelagic collections from 1958 through 1974. A simple simulation model of the female population was used to vary population parameters until a minimum chi-square value was achieved for the fit of simulated annual age structures to those observed in the pelagic collection. Population trajectories resulting from either a diminishing reproductive rate or diminishing adult female survival rate approximated estimated pup population sizes, which were not used in developing the model, except that a subset of five observations was used to constrain model trajectories to the general neighborhood of the observed pup populations. The main finding of the study was that adult female survival rates varied sharply during the 1964 through 1974 period, after the major period of harvests of female fur seals. Further study of the age structure data may thus be useful in evaluating the poorly understood long-term reduction in abundance of Pribilof fur seals.

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