A longitudinal study of senescence in a pinniped

2002 ◽  
Vol 80 (3) ◽  
pp. 395-401 ◽  
Author(s):  
Pierre A Pistorius ◽  
Marthán N Bester
Keyword(s):  
Longitudinal Study ◽  
Adult Female ◽  
No Reduction ◽  
Marion Island ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Reproductive Senescence ◽  
Southern Elephant Seals ◽  
Female Survival ◽  
Breeding Seasons

To measure the prevalence of senescence in southern elephant seals (Mirounga leonina Linn.) at Marion Island, changes in adult-female survival and breeding probabilities with age were quantified. Mark–recapture data that had been collected over a 17-year period were analysed using recently developed software to obtain likelihood estimates of survival and capture probabilities. With recapture effort constant over the study period, capture probabilities during the breeding seasons were used as indices of breeding probabilities. Longevity in the population was assessed from the resighting of tagged and hence known-age individuals. Less than a 1% difference between prime-age survival and post prime age survival was found over 8 cohorts of marked females. In addition, no reduction in survival of very old individuals was detected, suggesting the absence of senescence in terms of reduced survival in southern elephant seals. No evidence of reproductive senescence in terms of reduced breeding probability with age was detected. Mortality throughout the population therefore resulted in no individuals surviving to the age where physiological decline would become a mortality agent or result in failure to breed. Five percent of female southern elephant seals survived to age 10 and 0.5% to age 17.

Deep divers in even deeper seas: habitat use of male southern elephant seals from Marion Island

2012 ◽  
Vol 24 (6) ◽  
pp. 561-570 ◽  
Author(s):  
Trevor Mcintyre ◽  
Horst Bornemann ◽  
Joachim Plötz ◽  
Cheryl A. Tosh ◽  
Marthán N. Bester
Keyword(s):  
Habitat Use ◽  
Mixed Model ◽  
Marion Island ◽  
Mirounga Leonina ◽  
Fracture Zones ◽  
Elephant Seals ◽  
Sea Floor ◽  
Close Proximity ◽  
Southern Elephant Seals ◽  
Migration Strategies

AbstractWe describe the habitat use of 22 male southern elephant seals (Mirounga leonina) satellite tagged at Marion Island between 2004 and 2008. While a few areas of increased utilization appeared to be associated with areas of shallower bathymetry (such as sea-floor ridges and fracture zones), seals in our study did not target other areas of shallow bathymetry within close proximity to Marion Island. Rather, most elephant seals foraged pelagically over very deep water where much variation was evident in diel vertical migration strategies. These strategies resulted in generally deeper and longer dives than what has been reported for male elephant seals from other colonies. No significant differences were recorded for dive durations or dive depths between adults and sub-adults. However, younger animals displayed a positive relationship between dive durations and age, as well as between dive depths and age, while these relationships became negative for older animals. Mixed model outputs suggested that seals increased their aerobic fitness as migrations progressed, enabling them to undertake longer dives. We conclude that Marion Island male elephant seals exhibit much variability in dive strategy and are seemingly capable of exploiting a range of different prey types occurring in various depth layers.

scholarly journals Climate influences on female survival in a declining population of southern elephant seals ( Mirounga leonina )

2021 ◽  
Author(s):  
Sophia Volzke ◽  
Clive R. McMahon ◽  
Mark A. Hindell ◽  
Harry R. Burton ◽  
Simon J. Wotherspoon
Keyword(s):  
Mirounga Leonina ◽  
Elephant Seals ◽  
Southern Elephant Seals ◽  
Female Survival ◽  
Climate Influences

Age in relation to Breeding to Status of the Male Southern Elephant Seal, Mirounga leonina (L.), at Macquarie Island

1981 ◽  
Vol 8 (2) ◽  
pp. 327 ◽  
Author(s):  
E Jones
Keyword(s):  
Elephant Seal ◽  
Progressive Increase ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Macquarie Island ◽  
Southern Elephant Seals ◽  
Definition Of ◽  
Breeding Seasons ◽  
Breeding Status

Records of the breeding status of known-age male southern elephant seals at Macquarie I. were kept during five breeding seasons between 1969 and 1976. The seven status categories used were: beachmaster, secure assistant, medium harem owner, insecure assistant, small harem owner, attending bachelor, avoiding bachelor. There was a progressive increase in breeding status with age; none younger than 10-y-old bred: 16% of 10-y-olds, 30% of 11-y-olds and 55% of 12-y-olds did so; none younger than 12-y-old attained secure assistant status. At the earliest, beachmaster status may be attained at 14 y old, but no beachmasters of known age were recorded. Due to mortality and competition, most males do not breed and few breed for more than two seasons. Problems associated with the precise definition of status categories are discussed.

Variation in weaning mass of pups in relation to maternal mass, postweaning fast duration, and weaned pup behaviour in southern elephant seals (Mirounga leonina) at South Georgia

1993 ◽  
Vol 71 (9) ◽  
pp. 1772-1781 ◽  
Author(s):  
T. Arnbom ◽  
M. A. Fedak ◽  
I. L. Boyd ◽  
B. J. McConnell
Keyword(s):  
Mirounga Leonina ◽  
Elephant Seals ◽  
South Georgia ◽  
Energy Stores ◽  
Southern Elephant Seals ◽  
Fat Stores ◽  
Foraging Ability ◽  
Early Departure ◽  
Breeding Seasons ◽  
Large Groups

Female southern elephant seals, Mirounga leonina, assemble in large groups and each gives birth to a single pup which is nursed for some 3 weeks. Weaning mass is highly variable; some pups are three times as heavy as others at weaning. After weaning, the pup fasts for several weeks before departing to sea. The function of this fast is unknown. We examined the relationships between maternal mass, pup weaning mass, and pup behaviour during the postweaning fast in 377 pups and 128 adult females over four breeding seasons at South Georgia. Pup weaning mass was positively related to maternal postpartum mass, which accounted for 55% of the variation in weaning mass. Over all 4 years male pups were significantly heavier at weaning than female pups (130 vs. 123 kg) but this difference disappeared after maternal mass was controlled for. After fasting for 21–66 days, weaned pups went to sea at an average of 68% of weaning mass. Heavier pups remained on the beach longer after weaning than lighter pups. There was no evidence that pups synchronized their departure to sea. Only male pups were observed to take part in mock fights. With increasing age, weaned pups spent more time in the water. Mortality during the postweaning fast was negligible (0.1 %). The timing of departure of weaned pups may involve a trade-off between an early departure with greater fat (energy) stores but poorer foraging ability and a late departure with increased swimming, diving, and social skills but reduced fat stores.

Entanglement Of Pinnipeds At Marion Island, Southern Ocean: 1991-2001

2002 ◽  
Vol 24 (1) ◽  
pp. 141 ◽  
Author(s):  
G Hofmeyr ◽  
Maine M De ◽  
Mr Beste ◽  
S Kirkman ◽  
P Pistorius ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Fishing Industry ◽  
Marion Island ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Small Impact ◽  
Fur Seals ◽  
Southern Elephant Seals ◽  
Longline Fisheries

Some 101 fur seals Arctocephalus spp. and five southern elephant seals Mirounga leonina were recorded entangled in anthropogenic debris over ten years at Marion Island, Southern Ocean. Approximately 67% of materials causing entanglement originated in the fishing industry. Polypropylene packaging straps were the most common entangling material, followed by trawl netting. Longline hooks embedded in animals, fishing line and portions of plastic were only encountered after the inception in 1996 of longline fishing in the waters around Marion Island. The incidence of entanglement of Arctocephalus spp. during the 1996-2001 longline fisheries period increased by more than 50% over that of the 1991-1996 pre-longline fisheries period. An estimated 0.24% of the populations of fur seals were entangled. The numbers of entangled M. leonina are very low. Longline fishing has had a direct, albeit small, impact on the pinniped populations

Spatial and temporal patterns of changes in condition of southern elephant seals

2015 ◽  
Vol 28 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Trevor McIntyre ◽  
Ashleigh Donaldson ◽  
Marthán N. Bester
Keyword(s):  
Temporal Patterns ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
Marion Island ◽  
Mirounga Leonina ◽  
Foraging Success ◽  
Spatial And Temporal Patterns ◽  
Elephant Seals ◽  
Southern Elephant Seals ◽  
Gains And Losses

AbstractThe study of foraging success in marine predators is complicated by a lack of direct observations and relies mostly on proxy measures of foraging success. This study assessed spatial and temporal patterns of changes in body condition of southern elephant seals (Mirounga leonina) from Marion Island, based on changes in drift rates (which are related to gains and losses of blubber). Seals showed substantial individual variation in condition changes throughout migrations, which was not explained by age-, sex- or reproductive stages. Substantial variation was also evident in the spatial patterns of condition changes, although an area south of the Antarctic Polar Front (APF) between 10°E and 35°E was evidently associated with moderate, yet consistent gains in condition. Seals that foraged more distantly from Marion Island displayed more extreme gains and losses in condition, suggesting a possible risk/reward trade-off associated with foraging further afield versus closer to the island. Increased condition was consistently negatively related to sea surface temperature, suggesting that seals were generally improving their condition faster in cooler water masses. These results support previous studies predicting that continued warming of the Southern Ocean will result in changes to the habitat use patterns exhibited by southern elephant seals at sea.

Tag-loss in southern elephant seals, Mirounga leonina, at Marion Island

1997 ◽  
Vol 9 (2) ◽  
pp. 162-167 ◽  
Author(s):  
I.S. Wilkinson ◽  
M.N. Bester
Keyword(s):  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Island Population ◽  
Marion Island ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Tag Loss ◽  
Southern Elephant Seals ◽  
Marking Technique ◽  
Loss Rates

Rates of tag-loss are determined for Dalton Jumbo Rototags applied to the hind flippers of 4343 (2208 males, 2135 females) southern elephant seal (Mirounga leonina) pups at Marion Island over an eight year period from 1983–1990 as part of a demographic study of the species. Loss rates were the lowest recorded to date for this species (range 0.0–9.1%). No significant relationship existed between age and rate of tag-loss, neither was there any sex or year related differences in age-specific tag-loss rates. The low rates of loss highlight the value of tagging as a marking technique, and allow for high levels of confidence in the reliability of the population parameters that are derived from the tagging data collected for the Marion Island population.

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