Estado actual y tendencia de la población de lobos marinos de un pelo (Otaria favescens) en el litoral norpatagónico
Abstract
The Southern Sea Lion population in the Argentine coast was dramatically reduced between the 30’s and 50’s. 1n the north of Patagonia (Península Valdés and Golfo San Matías) present population size is about one: fifth to one tenth of the original size. The population trend was studied by monitoring the pups born in 1975 and from 1982 through 1990, including previous ii formation gathered in the area. The slope of the function relating the natural log of the number of pups born with time was not statistially different from 0 (F=2.87, p=0.05) until 1989. From 1990, it a slight increase was noted (F=6. 79, p=0.05). The: apparent stability of the last 15 years in central breeding areas obscure changes in social structure or spatial occupance with increase of the number of individuals, in haul out places occupied mainly by juveniles. At the light of the present information, ii can be concluded that, in the north of Patagonia, the sea lion population did not recover the original population size. This can lead to the hypothesis that the: population jumped from an attraction domain to another and a partial occupation of the ecological niche. On the other hand it could also be argued that recovery is taking place, but at an extremely slow rate. Marginal areas seem to be going through a temporal occupation by subadult males before becoming breeding areas.
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