No recent integrated estimate is available throughout the entire distribution. The worldwide population of southern elephant seals was estimated to be 650,000 in the mid 1990s. Colonies in the South Atlantic, which include the largest breeding aggregation located at South Georgia, are stable or growing, while those in the Southern Indian and Pacific Oceans have decreased by up to 50%. There is some evidence that weaning mass is lower at Macquarie, Heard and Marion Islands, and Iles Kerguelen, than in the South Georgia and Peninsula Valdés (Argentina) populations, suggesting that the Indian and Pacific Ocean populations may have a reduced food supply.

Traditionally, three distinct populations have been distinguished: South Georgia, Macquarie and Iles Kerguelen. However, elephant seals breeding at Península Valdes on the mainland of South America and at the Falkland (Malvinas) Islands are thought to be a distinct population from those at South Georgia. Similarly, the elephant seal populations at the Prince Edward Islands and Iles Crozet are also considered to be distinct from those at Iles Kerguelen and Heard Island, and the small populations in the Tristan de Cunha Islands and Gough Island may also be distinct. Additionally, some colonies have unknown affiliations (e.g. Bouvet). Thus, there may be at least five and perhaps more, distinct breeding populations, although their foraging areas overlap quite extensively at sea (SCAR 1991, Reijnders et al. 1993, Bailleaul 2007, Biuw 2007).

The most important southern elephant seal populations in the world have been either stable or decreasing sharply in the last 50 years (Hindell and Burton 1987, Guinet et al. 1992, Pistorius et al. 2004). Today, some of those that were in decline are apparently returning to a positive trend (Boyd et al. 1996, Guinet et al. 1999).The Valdés population has grown and now is stable (Campagna and Lewis 1992, Lewis et al. 1998). The reason for the differences in the trends in various areas is not known with certainty, but different levels of food availability associated with various oceanographic features seems to have played a role.

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