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Seasonal Movements of the Weddell Seal in McMurdo Sound, Antarctica

1965; Wiley; Volume: 29; Issue: 3 Linguagem: Inglês

10.2307/3798043

1937-2817

M. S. R. Smith,

Polar Research and Ecology

This paper reports a study on the seasonal changes in abundance of the Weddell seal (Leptonychotes weddelli Lesson) in McMurdo Sound, Antarctica. Aerial reconnaissance flights and visual methods were used to count the seals lying on the ice. seals have a daily feeding cycle resulting in the largest number lying on the at 4 PM. overwintering population was estimated at 250 and the maximum summer population at 2,670. arrival of the seals in McMurdo Sound can be divided into two parts: (1) first influx of pregnant females in October, and (2) second influx of the main population November-December. There was a secondary buildup of seals in early February. Details of the first and second influx are shown by a study of the area from Knob Point to the confluence of the Erebus Glacier Tongue and Hut Point Peninsula. Statistical analysis showed that the numbers of seals lying on the was significantly related to wind velocity. The Weddell seal is circumpolar, and its normal habitat is the inshore waters of the Antarctic continent and adjacent islands. It spends much time in the water, but emerges at intervals to lie out on the beaches or on isolated floes not far from land. . . . It is the most southerly ranging mammal, apart from man himself, and is the seal most specialised for life in high latitudes, where so much of the year must be spent under the ice (Bertram 1940: 5-6). This paper describes fluctuations in numbers of the Weddell seal in McMurdo Sound (77 degrees, 30 minutes south, 166 degrees east) between October and March in the three seasons 1961-64. work is part of a long-term project by the University of Canterbury Antarctic Biology Unit and the New Zealand Department of Scientific and Industrial Research in their research program on conservation of Antarctic flora and fauna. This study on the Weddell seal was initiated to establish the state of the population in McMurdo Sound because, since 1956, seals have been killed for dog food. I thank G. Markham, Superintendent of Antarctic Division, Department of Scientific and Industrial Research, and the leaders and members of the New Zealand Antarctic Research Program, 1961-62, 1962-63, 1963-64, for the help generously given. I wish to acknowledge my debt to VX-6 Squadron of the United States Navy Antarctic Support Activities for aerial reconnaissance flights. Also I acknowledge Professor G. A. Knox and Dr. B. Stonehouse, W. Featherston, O. Sutherland, and I. Spellerberg for help in the field and in discussion of these results. For the statistics I acknowledge the help of Miss E. Stevenson of the Applied Mathematics Division, D. S. I. R.