CONICET | Buscador de Institutos y Recursos Humanos

The population along the coast of Argentina is distributed across 19 colonies (rookeries and haul-out sites), mainly located at Isla Rasa, Isla Arce and Isla Escondida (Chubut province, Figure 1), where a rough estimation of the rate of increase was calculated at about 8%. Fur seal colonies across Tierra del Fuego and Isla de los Estados (Fuegian archipelago) were surveyed in 1997, at which time 4,200 SAFS were estimated (including 358 pups). However, the estimated population trend for Fuegian archipelago is not available due to the lack of data. In this context it was found a recovering population of SAFS in the southwestern Atlantic and an interconnection between areas with different trends, therefore, the aim of the present study is to estimate the abundance and trend of SAFS in the Fuegian archipelago and analyze and describe changes in the social composition and spatial distribution of colonies through time (1997?2012). SAFS from the Fuegian archipelago are recovering. This process includes the establishment of new colonies, and the change of the social structure of others. The high rates of increase estimated are possibly due to a combination of immigration and intrinsic population growth. Therefore, considering that the changes observed in the colonies shows that the fur seals are going through a recolonization process, it is essential to keep monitoring the species and its population trend. The results of the present study and future counts will contribute in this effort, providing data for SAFS in the Fuegian archipelago to evaluate future modifications of the abundance and structure of the colonies at the southern limit of its distribution. Not only is such long-term monitoring of value for the conser-vation and management of this species, but marine mammal population trend can serve as indicators of the general health of an ecosystem.

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