Twinning in southern elephant seals: the implications of resource allocation by mothers

2003 ◽  
Vol 30 (1) ◽  
pp. 35 ◽  
Author(s):  
Clive R. McMahon ◽  
Mark A. Hindell
Keyword(s):  
Reproductive Success ◽  
Rare Event ◽  
Elephant Seal ◽  
Lactation Period ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Growth And Survival ◽  
Southern Elephant Seals ◽  
Lactation Duration ◽  
Pup Growth

Southern elephant seals (Mirounga leonina) typically give birth to a single pup and raise it over a short 24-day lactation period. Lactation is characterised by: maternal fasting, rapid pup growth and abrupt weaning after which the weaned pups rely on stored fat for growth and survival. Females are not able to transfer all of their stored resources to their pups because they themselves need to use some to return to their remote foraging grounds after the breeding effort. Therefore the amount of energy expended by a female during lactation may affect not only the survival of her pup, but her own survival and future reproductive success. Female southern elephant seals are therefore under strong selective pressure to allocate finite amounts of resources to their pups. In the rare event of producing twins, females that wean both pups are likely to experience reduced reproductive success. Twin births accounted for 0.38% of all the observed elephant seal births at Macquarie Island in 1999. The mean birth masses, weaning lengths and lactation duration for twin and singleton pups did not differ significantly but weaning mass, weaning girths and lactation growth rates did differ significantly. In all cases, singleton pups were larger and grew faster than twin pups. Twin pups suffered greater pre-weaning mortality than singletons (16.7% and 4.6% respectively) and fewer were seen alive after 18 months (20% compared with 47% respectively).

Growth From Birth to 20 Days in the Elephant Seal, Mirounga-Leonina, at Macquarie-Island

1987 ◽  
Vol 35 (4) ◽  
pp. 307 ◽  
Author(s):  
GJ Little ◽  
MM Bryden ◽  
A Barnes
Keyword(s):  
Birth Weight ◽  
Elephant Seal ◽  
Lactation Period ◽  
Mirounga Leonina ◽  
Average Birth Weight ◽  
Macquarie Island ◽  
Seal Population ◽  
Antarctic Research ◽  
Breeding Seasons ◽  
Pup Growth

Recent investigations by members of Australian National Antarctic Research Expeditions to Macquarie I. have revealed a decrease in the elephant seal population there of approximately 50% over the last 36 years. Lower birth weights and/or slower growth during the lactation period might explain this decrease. To test this hypothesis, growth of pups was studied from birth to 20 days during the 1984 and 1985 breeding seasons; these results were compared as far as possible with similar results for the 1956 and 1965 seasons. Average birth weight has not changed significantly over the last 20 years; it is suggested that if food supply were a major factor in the reduction of the elephant seal population, then birth weights in 1985 would have been lower than those in 1956. At birth, male pups were 7% (3 kg) heavier than female pups in 1985. Results from previous years suggest that this is probably normal in this seal. The weight of pups near weaning (20 or 21 days old) is shown to be significantly less in 1984 and 1985 than 1965, but this may be explained by differences in methodology. It is concluded that, on the evidence available, the pattern of pup growth on Macquarie I. has not altered significantly with time, but more work is needed to reach a clear conclusion.

Early Growth and Milk-Composition in Southern Elephant Seals (Mirounga-Leonina)

1994 ◽  
Vol 42 (6) ◽  
pp. 723 ◽  
Author(s):  
MA Hindell ◽  
MM Bryden ◽  
HR Burton
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Post Partum ◽  
Fat Content ◽  
Lactation Period ◽  
Mirounga Leonina ◽  
Maternal Condition ◽  
Average Growth ◽  
Elephant Seals ◽  
Southern Elephant Seals

Growth rates and changes in body composition of pups were monitored during the 3-week lactation period of southern elephant seals at Macquarie Island. Despite a slight decrease in weight in the first days post-partum, pups attained a mass of 114+/-16.6 kg (mean+/-s.d.) at weaning, representing an average growth rate of 3.53+/-0.80 kg day-1 over the entire lactation period. The proportion of body mass represented by fat was less than 3% at birth, increasing to 40.8+/-12.7% at weaning. Lean tissue mass altered little for most of the lactation period, but did show an increase in the last four days. The fat content of the milk reflected these changes, starting at 16.1+/-6.98% on Day 1 of lactation and increasing to 39.5+/-15.2% about the time of weaning. Fat content of the milk was, however, highly variable and at weaning ranged from 7% to 55%. Although the growth rate of the pup was correlated with mass lost by its mother during lactation, there was no relationship between maternal mass and weaning weight of pups. It is suggested that growth rates may be related to maternal condition and not simply mass, and, further, that differences in growth rates between populations of southern elephant seals are related to maternal energy reserves.

Physiological implications of continuous, prolonged, and deep dives of the southern elephant seal (Mirounga leonina)

1992 ◽  
Vol 70 (2) ◽  
pp. 370-379 ◽  
Author(s):  
Mark A. Hindell ◽  
David J. Slip ◽  
Harry R. Burton ◽  
Michael M. Bryden
Keyword(s):  
Resting Metabolic Rate ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Adult Males ◽  
Mirounga Leonina ◽  
Physiological Mechanisms ◽  
Elephant Seals ◽  
Aerobic Dive Limit ◽  
Southern Elephant Seals ◽  
Extended Surface

The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested that they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use physiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives.

scholarly journals Calibration procedures and first data set of Southern Ocean chlorophyll <i>a</i> profiles collected by elephant seal equipped with a newly developed CTD-fluorescence tags

2012 ◽  
Vol 5 (2) ◽  
pp. 853-891 ◽  
Author(s):  
C. Guinet ◽  
X. Xing ◽  
E. Walker ◽  
P. Monestiez ◽  
S. Marchand ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Elephant Seal ◽  
In Situ Observation ◽  
Mirounga Leonina ◽  
Data Set ◽  
Elephant Seals ◽  
Phytoplankton Concentration ◽  
Southern Elephant Seals ◽  
Indian Sector

Abstract. In-situ observation of the marine environment has traditionally relied on ship-based platforms. The obvious consequence is that physical and biogeochemical properties have been dramatically undersampled, especially in the remote Southern Ocean (SO). The difficulty in obtaining in situ data represents the major limitations to our understanding, and interpretation of the coupling between physical forcing and the biogeochemical response. Southern elephant seals (Mirounga leonina) equipped with a new generation of oceanographic sensors can measure ocean structure in regions and seasons rarely observed with traditional oceanographic platforms. Over the last few years, seals have allowed for a considerable increase in temperature and salinity profiles from the SO. However we were still lacking information on the spatio-temporal variation of phytoplankton concentration. This information is critical to assess how the biological productivity of the SO, with direct consequences on the amount of CO2 "fixed" by the biological pump, will respond to global warming. In this research program, we use an innovative sampling fluorescence approach to quantify phytoplankton concentration at sea. For the first time, a low energy consumption fluorometer was added to Argos CTD-SRDL tags, and these novel instruments were deployed on 27 southern elephant seals between 25 December 2007 and the 4 February 2011. As many as 3388 fluorescence profiles associated with temperature and salinity measurements were thereby collected from a vast sector of the Southern Indian Ocean. This paper address the calibration issue of the fluorometer before being deployed on elephant seals and present the first results obtained for the Indian Sector of the Southern Ocean. This in situ system is implemented in synergy with satellite ocean colour radiometry. Satellite-derived data is limited to the surface layer and is restricted over the SO by extensive cloud cover. However, with the addition of these new tags, we're able to assess the 3 dimension distribution of phytoplankton concentration by foraging southern elephant seals. This approach reveals that for the Indian sector of the SO, the surface chlorophyll a (chl a) concentrations provided by MODIS were underestimated by a factor of the order of 2–3 compared to in situ measurements. The scientific outcomes of this program include an improved understanding of both the present state and variability in ocean biology, and the accompanying biogeochemistry, as well as the delivery of real-time and open-access data to scientists (doi:10.7491/MEMO.1x).

Southern elephant seals north of the Antarctic Polar Front

2006 ◽  
Vol 18 (2) ◽  
pp. 213-221 ◽  
Author(s):  
M. Lewis ◽  
C. Campagna ◽  
M.R. Marin ◽  
T. Fernandez
Keyword(s):  
South America ◽  
Atlantic Coast ◽  
Elephant Seal ◽  
Polar Front ◽  
Tierra Del Fuego ◽  
Suitable Habitat ◽  
Antarctic Polar Front ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Southern Elephant Seals

This paper reports on sightings and dispersion of individual southern elephant seals (Mirounga leonina) along the Atlantic and Pacific coasts of South America based on reports of tagged/marked seals from Patagonia and of animals of unknown origin. From 154 sightings, encompassing at least 354 individuals, we found that individuals dispersed to subequatorial latitudes on both sides of the continent, and to more temperate sites, in the Magellanic region of Tierra del Fuego. Nineteen sites were visited by tagged seals from the established colony of Península Valdés (PV, Argentina). PV and the smaller seal population of the Falklands/Malvinas were regularly connected by adults of both sexes. There were more sightings of males than females. No incipient new breeding colonies were found along the Atlantic coast of South America. Some observations coincided with places where elephant seals had been recorded or exploited in the seventeenth and eighteenth centuries. A shortage of suitable habitat for expansion and proximity to predictable food could act as a stabilizing process preventing colonization of new areas from PV. Dispersion data, coherent with population genetics, support a Patagonian elephant seal stock.

scholarly journals Movement responses to environment: fast inference of variation among southern elephant seals with a mixed effects model

2018 ◽  
Author(s):  
I. D. Jonsen ◽  
C. R. McMahon ◽  
T. A. Patterson ◽  
M. Auger-Méthé ◽  
R. Harcourt ◽  
...  
Keyword(s):  
Sea Ice ◽  
Movement Patterns ◽  
Elephant Seal ◽  
Mixed Effects ◽  
Foraging Strategies ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Movement Model ◽  
Elephant Seals ◽  
Southern Elephant Seals

AbstractLike many species, movement patterns of southern elephant seals (Mirounga leonina) are being influenced by long-term environmental change. These seals migrate up to 4000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among individuals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast-estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among-individual variability in southern elephant seal environment-movement relationships. We found that seals making foraging trips to the sea-ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea ice coverage and had variable responses to chlorophyll a concentration, whereas seals that foraged pelagically reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, pelagic foragers may encounter more productive habitat but sea-ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat use.

Cephalopod diet of the southern elephant seal, Mirounga leonina, at King George Island, South Shetland Islands

2000 ◽  
Vol 12 (1) ◽  
pp. 16-19 ◽  
Author(s):  
G.A. Daneri ◽  
A.R. Carlini ◽  
P.G.K. Rodhouse
Keyword(s):  
Stomach Contents ◽  
Elephant Seal ◽  
South Shetland Islands ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
King George Island ◽  
Elephant Seals ◽  
Shetland Islands ◽  
Important Prey ◽  
Southern Elephant Seals

In the summer of 1995/96, 25 southern elephant seals, Mirounga leonina, were stomach lavaged at Stranger Point, King George Island, South Shetland Islands. Cephalopod remains were present in 72% of the individuals sampled (n = 18). Seven species of squid and three of octopus were identified. The squid Psychroteuthis glacialis was the most important prey in terms of numbers (77%), biomass (80.8%) and frequency of occurrence (94.4%). Next in importance in terms of mass was the squid Alluroteuthis antarcticus (7.8%) in the diet of females and the octopodid Pareledone ?charcoti in the diet of males (13.2%). Females preyed on a wider variety of squid taxa than males (7 vs 3) but octopodids occurred only in stomach contents from males. The predominance of P. glacialis in the prey of the South Shetland Islands elephant seals can be explained by the southerly location of the foraging areas of this population compared to South Georgia, Heard and Macquarie islands, where the diet of southern elephant seals has previously been analysed. Psychroteuthis glacialis is the predominant squid in waters close to the Antarctic continent.

Ultrasonic Measurement of Blubber Thickness of the Southern Elephant Seal, Mirounga-Leonina (Linn)

1987 ◽  
Vol 35 (3) ◽  
pp. 207 ◽  
Author(s):  
NJ Gales ◽  
HR Burton
Keyword(s):  
Subcutaneous Fat ◽  
Elephant Seal ◽  
Ultrasonic Measurement ◽  
Southern Elephant Seal ◽  
Future Research ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Non Invasive ◽  
Fat Reserves ◽  
Southern Elephant Seals

Ultrasound measurements of subcutaneous fat at 18 body sites on each of 23 southern elephant seals Mirounga leonina (Linn.), together with circumference and length measurements, were used to estimate the total subcutaneous blubber weight on each animal. Twelve cows (including animals that were pregnant and others at early, mid-, late and post-lactation), 10 males and one male pup were anaesthetised for these measurements, made at Heard I. (53�01'S.,73�23'E.) on various dates in October and November 1985. Comparison of the estimates of blubber weight from cows at various stages of lactation allowed a mean blubber loss of 62.8 kg per cow per lactation to be calculated. It is suggested that measuring variations in the subcutaneous fat reserves of cows coming ashore to pup at Heard I. may be one relevant approach in any future research that attempts to explain the 60% drop in pup production at that island between 1949 and 1985. The use of ultrasound to estimate the subcutaneous fat reserves of seals was shown to be a safe, non-invasive and logistically practical technique.

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.

scholarly journals Dispersal of southern elephant seals (Mirounga leonina) from Davis Base, Antarctica: Combining population genetics and tracking data

2021 ◽  
Author(s):  
Michelle Chua ◽  
Simon Ho ◽  
Clive McMahon ◽  
Ian Jonsen ◽  
Mark de Bruyn
Keyword(s):  
Genetic Diversity ◽  
Marine Environment ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Tracking Data ◽  
Mirounga Leonina ◽  
Long Distance ◽  
Elephant Seals ◽  
Macquarie Island ◽  
Southern Elephant Seals

Marine animals such as the southern elephant seal (Mirounga leonina) rely on a productive marine environment and are vulnerable to oceanic changes that can affect their reproduction and survival rates. Davis Base, Antarctica, acts as a moulting site for southern elephant seals that forage in Prydz Bay, but the genetic diversity and natal source populations of these seals has not been characterized. Determining the genetic diversity of moulting populations like this one provides essential information on seal dispersal, inter-population mixing, and foraging behaviours. In this study, we combined genetic and animal tracking data on these moulting seals to identify levels of genetic diversity, natal source population, and movement behaviours during foraging and haul-out periods. Using mitochondrial sequence data, we identified two major breeding lineages of seals at Davis Base. We found that the majority of the seals originated from breeding stocks within the South Atlantic Ocean and South Indian Ocean. One seal was grouped with the Macquarie Island breeding stock (South Pacific Ocean). The Macquarie Island population, unlike the other two stocks, is decreasing in size. Tracking data revealed long-distance foraging activity of the Macquarie Island seal around Crozet Islands. We speculate that changes to the Antarctic marine environment have resulted in a shift in foraging and dispersal strategies, which subsequently affects seal population growth rates. These findings have implications for conservation management plans aimed at improving the population status of the southern elephant seal.

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