Antarctic Seal Study

Press, Volume CVI, Issue 31307, 1 March 1967, Page 14

Antarctic Seal Study

(Special Crjpdt. N.ZPA.7 SCOTT BASE. Antarctic seals are relatively undisturbed by man and therefore make an excellent “vehicle” for studying the life and habits of such mammals. At Scott Base the population dynamics of Weddel seals in McMurdo Sound are being studied by a two-man field party from the University of Canterbury. The project was started last summer by lan Stirling and will be continued by him for three seasons. Assisting Mr Stirling this season is Rod East.

“This study of Weddell seals will apply to Antarctic seals In particular, to all seals generally, and all large vertebrates as a general principle,” said Mr Stirling.

The estimated Weddell sea] population of Antarctica’s coastal waters is 600,000. There are about 2500 in MeMurdo Sound and a quarter to a third of this number has been tagged for the study. A Weddell seal grows to about 10 feet, weighs up to a thousand pounds, and lives for a maximum of 15 years. Pups of 801 b are borne in mid-October and double their weight in 10 days. They are weaned at six weeks then disappear, possibly into the pack ice which rings Antarctica, before returning to breed three years later. Mr Stirling is a graduate of the University of British Columbia, Vancouver, and is studying for his doctorate at Canterbury under a scholarship from the University Grants Committee. He has studied birds and animals in the Arctic for the National Museum of Canada and was granted a scholarship by the Canadian Wildlife Service for a behavioural study of grouse in British Columbia.

“In McMurdo Sound the Weddells are in their natural situation, rookeries are accessible, the seals easy to tag and resightings are frequent,” said Mr Stirling. “The ease of transport between New Zealand and Scott Base, together with the availability of United States ship and helicopter support in McMurdo Sound, affords an excellent opportunity for studying the undisturbed Weddell rookeries.

“About the only other seals in the world whose population dynamics have been studied in detail are the elephant seals of McQuarry Island and the .fur seals of Pribilof Island, just off the Alaska Peninsula. Other Arctic populations have been harvested heavily and not allowed to return to their original numbers,” he said. “It is economically profitable to harvest seals for pelts and blubber, as has been shown in the north, and it is feasible this may happen in the south. Aleardy there have been two exploratory Norwegian expeditions hunting crabeater seals in the Weddell Sea of Antarctica, south of South America,” said Mr Stirling. Indicative of Antarctica’s

rich sea harvest is that between 1923 and 1931, 66 million gallons of whale oil were taken from the Ross Dependency. The New Zealand Government received £37,051 15s in fees and royalties from factories in the area. Birth and death rates, the expected survival of age groups, and productivity, are included in Mr Stirling’s study. Eventually it will be possible to predict which age or sex classes in particular concentrations can be safely harvested as an economic resource.

“Pups are tagged as well as a number of adults, then the daily and seasonal movements of individuals and populations can be fallowed. The seals feed mainly on squids and fish, they can dive as deep as 2000 feet and stay under water for a maximum of 40 minutes,” said Mr Stirling.

“Normally they feed, then lie snoozing on the sea ice in the afternoon and early evening. They either scramble on to the ice at the sea edge, come up through a crack, or chew a hole through a weak spot. Some Weddells stay in McMurdo Sound all winter beneath the ice by keeping a breathing-hole open with their teeth,” he said. To check the suggestion that young seals disappear into the pack ice, Messrs Stirling and East sailed on the United States Coast guard ships, Staten Island and Glacier, up and down McMurdo Sound

and into the Ross Sea pack ice. No concentrations of young were found. However, with the aid of helicopters based on the ships older seals - were observed along the Victoria coast. Each summer a limited ' number of seals is killed for i study of their internal organs. : Once portions have been col- ■ lected by scientists the rei maining carcases are fed to i the Scott Base dogs. Mr Stirling is collecting the canine teeth from the seals which are killed. This tooth is hollow and builds internally each year, giving an accurate measure of the seal's age. Female ovaries are also examined to get an indication of their reproductive condition. As a pilot investigation this summer, pulse rates of sleeping seals were checked with an electronic stethoscope and body temperatures measured under varying environmental conditions. “It appears the flippers help to regulate body heat, and this would make an excellent study in coming seasons,” said Mr Stirling-. As well as being field as slstant, Mr East is studying wounding and infection in the Weddell seal. He is a B.Sc. honours student and was granted the New Zealand Antarctic Society (Canterbury branch) bursary to work in Antarctica this season. University students are not paid while doing research in Antarctica and each season this bursary is given to one Canterbury University student. Mr East is recording cuts on seals. Many are infected, and he is attempting to find the micro-organisms causing the infection. Swabs are taken from cuts and the bacteria cultured. “During the mating season of November and December the males fight and wound each other. Unlike crabeater seals, few scars on Weddells . are caused by killer whale at- 1 tacks,” said Mr East