Skin temperatures during free-ranging swimming and diving in antarctic fur seals

This study tests the hypothesis that an endothermic homeotherm should minimise heat flux in cold polar waters by minimising skin temperature. Temperature variability was measured at the surface of the skin of three Antarctic fur seals (Arctocephalus gazella) at intervals of 2 s over a total of 9.7 days while they were swimming and diving freely in polar waters at temperatures of 1.5-4 degrees C. The temperature difference (capdelta T) between skin on the dorsal thorax and the water varied from more than 20 degrees C to close to equality over periods of less than 1 h. Shorter-term variations in capdelta T of up to 5 degrees C occurred in association with diving, although these types of variations also occurred without diving. In general, capdelta T began to decline during the descent phase of a dive and began to increase again during the ascent or at the end of the dive. One of the three individuals examined showed little variation in capdelta T, which remained low (approximately 3 degrees C) throughout the experiment. In the other two fur seals, capdelta T tended to decline during periods of sustained diving and usually increased during periods spent at the surface. Mean calculated heat flux varied from 95 to 236 W m(−)(2) depending on the individual. Metabolic rates based on these calculated heat fluxes were towards the lower end of those measured in previous studies using different methodologies. The study has shown that Antarctic fur seal skin temperature is highly dynamic and suggests that the thoracic surface is an organ used for active thermoregulation.

Download Full-text

Attendance behaviour of Antarctic and subantarctic fur seal females at Marion Island

Antarctic Science ◽

10.1017/s0954102090000438 ◽

1990 ◽

Vol 2 (4) ◽

pp. 309-312 ◽

Cited By ~ 12

Author(s):

Marthán N. Bester ◽

Peter A. Bartlett

Keyword(s):

Arctocephalus Gazella ◽

Marion Island ◽

Fur Seals ◽

Fur Seal ◽

Lactating Females ◽

The Mean ◽

Temperate Environment ◽

The Difference ◽

Antarctic Fur Seals ◽

Subantarctic Fur Seals

The female attendance behaviour of Antarctic fur seals (Arctocephalus gazella) and subantarctic fur seals (A.tropicalis), which breed sympatrically on subantarctic Marion Island, was investigated. Over the same period after the breeding season, the mean duration of feeding trips to sea, and percentage of time spent at sea, did not differ significantly between lactating females of the two species. The difference in mean duration of shore visits was significant and the longer onshore attendance of A. tropicalis probably related to the lower demand by their pups which grow at a slower rate. The subpolar maternal adaptations of A. gazella were unchanged under the more temperate environment at Marion Island, and it remains to be established unequivocally whether conditions there are limiting to the species.

Download Full-text

Wintertime overlaps between female Antarctic fur seals (Arctocephalus gazella) and the krill fishery at South Georgia, South Atlantic

PLoS ONE ◽

10.1371/journal.pone.0248071 ◽

2021 ◽

Vol 16 (3) ◽

pp. e0248071

Author(s):

Connor C. G. Bamford ◽

Victoria Warwick-Evans ◽

Iain J. Staniland ◽

Jennifer A. Jackson ◽

Philip N. Trathan

Keyword(s):

Antarctic Krill ◽

Euphausia Superba ◽

Arctocephalus Gazella ◽

Habitat Models ◽

South Georgia ◽

Fur Seals ◽

Fur Seal ◽

Ice Edge ◽

Future Work ◽

Antarctic Fur Seals

The diet of Antarctic fur seals (Arctocephalus gazella) at South Georgia is dominated by Antarctic krill (Euphausia superba). During the breeding season, foraging trips by lactating female fur seals are constrained by their need to return to land to provision their pups. Post-breeding, seals disperse in order to feed and recover condition; estimates indicate c.70% of females remain near to South Georgia, whilst others head west towards the Patagonian Shelf or south to the ice-edge. The krill fishery at South Georgia operates only during the winter, providing the potential for fur seal: fishery interaction during these months. Here we use available winter (May to September) tracking data from Platform Terminal Transmitter (PTT) tags deployed on female fur seals at Bird Island, South Georgia. We develop habitat models describing their distribution during the winters of 1999 and 2003 with the aim of visualising and quantifying the degree of spatial overlap between female fur seals and krill harvesting in South Georgia waters. We show that spatial distribution of fur seals around South Georgia is extensive, and that the krill fishery overlaps with small, highly localised areas of available fur seal habitat. From these findings we discuss the implications for management, and future work.

Download Full-text

Twins or not? Genetic analysis of putative twins in Antarctic fur seals, Arctocephalus gazella, on the South Shetland Islands

Journal of Experimental Marine Biology and Ecology ◽

10.1016/j.jembe.2011.10.010 ◽

2012 ◽

Vol 412 ◽

pp. 13-19 ◽

Cited By ~ 8

Author(s):

Carolina A. Bonin ◽

Michael E. Goebel ◽

Gregory M. O'Corry-Crowe ◽

Ronald S. Burton

Keyword(s):

Genetic Analysis ◽

South Shetland Islands ◽

Arctocephalus Gazella ◽

The South ◽

Shetland Islands ◽

Fur Seals ◽

Antarctic Fur Seals

Download Full-text

The composition of the milk of antarctic (Arctocephalus gazella) and subantarctic (A. tropicalis) fur seals at Macquarie Island

Australian Journal of Zoology ◽

10.1071/zo98067 ◽

1999 ◽

Vol 47 (6) ◽

pp. 593 ◽

Cited By ~ 10

Author(s):

Simon D. Goldsworthy ◽

Helen M. Crowley

Keyword(s):

Water Content ◽

Energy Content ◽

Post Partum ◽

Milk Composition ◽

Arctocephalus Gazella ◽

Macquarie Island ◽

Fur Seals ◽

Fur Seal ◽

Gross Energy ◽

Subantarctic Fur Seals

The composition of milk collected from 36 antarctic (Arctocephalus gazella) and 17 subantarctic fur seals (A. tropicalis) breeding sympatrically at Macquarie Island was examined over the first 100 days of lactation in the 1990/91 season. The mean composition of milk in A. gazella and A. tropicalis was 41.3% and 44.6% water, 39.8% and 38.6% lipid, 18.1% and 16.1% protein, and the estimated gross energy content of milk was 19.9 and 18.9 kJ g–1, respectively. Neither the composition of milk nor its energy density differed significantly between species, despite a difference of 4–6 months in lactation length. Water content of milk could be used to predict lipid (r2 = 0.67) and protein (r2 = 0.57) content, but was most accurate at predicting gross energy content (r2 = 0.97). These relationships were the same for each species. The water content of milk decreased throughout the first 100 days of lactation in both species, while lipid, protein and energy content all increased. The addition of maternal mass into regression analysis with days post-partum increased the significance of models predicting the content of lipid and proteins in the milk, but not those predicting the water or gross energy content. Milk collected on the first day of 2-day attendance bouts had, on average, 9% greater lipid content, and 5% greater protein content than milk collected on the second day. The growth rates of subantarctic fur seal pups were significantly lower than those of antarctic fur seal pups over the first month of growth, suggesting that (despite similar milk composition, attendance patterns and diet of the two species of fur seal) the overall rates of energy transfer from mother to pup in subantarctic fur seals is lower than in antarctic fur seals.

Download Full-text