Southern Elephant Seal

Common Name:Southern Elephant Seal

Scientific Name: Mirounga leonina

Southern Elephant Seal

Southern elephant seals (Mirounga leonina) have a circumpolar distribution and breed on subantarctic islands. There are four main stock groups: South Georgia, Peninsula Valdez, Iles Kerguelen (including Heard Island), and Macquarie Island.

From 1950 to 1985 the elephant seal populations at Macquarie Island, Heard Island, and others of the Iles Kergulen stock declined by about 50%. Since then the population at Heard and Kerguelen has remained relatively stable but the Macquarie population has continued to decline at about 1.2% per year.

Description

Southern elephant seals (Mirounga leonina) are the largest of all seals with males reaching 4-5 m in length and 3 500 kg in weight. Females are much smaller at 2-3 m in length and only 500 kg in weight. Southern elephant seals are coloured rusty grey-brown and are covered with thick blubber. Mature males have a large 'trunk', or proboscis which is used to amplify their vocalisations and, together with their bulk, gives rise to their name 'elephant' seal. They often appear cumbersome and indifferent to humans yet, despite their awkwardness, the speed with which they can move their bulk makes them potentially dangerous if harassed.

Size

Adult males can weigh up to 3000kg while adult females weigh between 300 and 900kg just prior to giving birth. Pups weigh about 40kg at birth and are weaned after 24 days by which time they weigh on average 120kg. A large weaner may weigh in excess of 220kg.

Behaviour

Southern elephant seals can dive to over 1500m in depth and can stay submerged for up to 2 hours. Most dives are about 30minutes duration and of depths between 300 and 800m and can dive constantly while at sea spending about 2 minutes on the surface between dives.

Diet

Southern elephant seals feed on squid and fish.

Breeding

Southern elephant seals breed in colonial groups called harems. A single dominant male usually can control a harem of up to 50 females. Once harems get larger than this the dominant beachmaster will allow assistant beachmasters to reside within the harem. Harems can grow to over 1000 females with over 30males.

Southern elephant seals have a thick layer of blubber that sustains them during the breeding season as they do not feed during this time. For many years seals were killed for their blubber which was boiled down to make oil.

Move

Southern elephant seals travel long distances to their foraging areas. Males forage mainly on the Antarctic continental shelf while females forage in more pelagic areas, such as off the Antarctic shelf within the pack ice, or near the Antarctic Polar Frontal Zone. Foraging areas can be several thousand kilometres away from their breeding islands.