Immigration and emigration in the isolated White Island Weddell seal (Leptonychotes weddellii) population

Abstract

The small, isolated population of Weddell seals (Leptonychotes weddellii Lessen) at White Island, Antarctica, is the southernmost breeding population of mammals in the world and occurs alongside an island surrounded by thick, glacial ice (Hückstädt 2017). Historical records suggest that the White Island population was founded at some point in the late 1950s by immigrant seals from the nearby Erebus Bay Weddell seal population when part of the Ross Sea and McMurdo ice shelves broke out, which allowed seals to swim underneath the ice shelf to reach White Island (Heine 1963, Shaughnessay 1969). However, as the Ross Sea and McMurdo ice shelves advanced, the distance between White Island and the ice-free ocean to the north grew, which trapped and isolated the founding seals at White Island (for a more detailed history of the population, see Gelatt et al. 2010).