Diurnal and seasonal migration of Weddell seals (Leptonychotes weddellii) in the region of the Argentine Islands archipelago (Western Antarctic)

• Published in: Ukraïnsʹkyĭ antarktychnyĭ z͡h︡urnal no. 14; pp. 158 - 162
• Main Authors: Dykyj, I V, Drongovs'ka, MO
• Format: Journal Article
• Language: English
• Published: 01.01.2015
• Subjects: Leptonychotes weddellii; Marine; Antarctica, Antarctic Peninsula
• ISSN: 1727-7485

The material was collected during three Ukrainian Antarctic Expeditions (2006-2007, 2009-2010, 2011-2012) in the area of the Argentine Islands archipelago (Western Antarctica). The studies of the Weddell seals (Leptonychotes weddellii)migrations were conducted using a method of photographing individual spots on the animal belly. Sex ratio and age of the specimens were determined. Results of re-registration of the tagged seals and photographic database showed that in winter and spring most seals dwelled within the archipelago. However, they were often registered on Winter Is., Skua Is., Galindez Is. and Grotto Is. during the winter-spring period. Some individuals were reported on Leopard Is., Forge Is. and Barchans Is. L. weddellii keep to specific places of rest during the day and always come back after a night of hunt. During the lactation period, males are usually located within the limits of 1-1.5 km from females, which feed in the area of the Penola Strait, the Cornice Channel, and near the coastline of the Winter Is., not leaving their pups for a long time. It is found out that both males and females of this species can overcome great distances (over 25 km). However, a phenomenon of topical conservatism is revealed for the Weddell seals. Some specimens are strongly tied to specific resting places, protected from wind and ocean waves. L. weddelli has a high level of abundance in December-January in the area of the archipelago. 5-7 individuals of seals are always reported within the Stella Creek Strait, where males and animals of the last year generation predominate. In February single specimens of both sexes are observed mainly in the area of Barchans Is., Anagrams Is., Winter Is., Shelter Is. and Rasmussen Is. During the summer seals migrate southwards, outside the archipelago. In particular, animals are reported on Barthelot Is., Darboux Is. and Cape Perez. In late summer and early autumn, most seals migrate northwards and north-westwards, probably, due to ice conditions: 26 individuals of both sexes are marked on the coast of Cruls Is. in February 2007. It is suggested that daily migrations of the Weddell seals are associated with presence of krill in the water area. Seasonal migrations of this species are closely related to the ice conditions, food availability and reproductive period.