Leopard seals live mostly on and around the pack ice of Antarctica, in Antarctic and sub-Antarctic waters, and they usually live alone. Counting them is a hard job. Aerial seal surveys use helicopters with paired observers searching the same strip of ice independently. In one survey, so few were sighted that it was a major obstacle in making population estimates.

One source estimates a population of at least 35,000 leopard seals but says the estimate is probably low, as of November 2026. An estimate from 2000 put leopard seals at 200,000 to 400,000, as of November 2026. Low densities of solitary animals over vast areas are difficult to estimate.

As of November 2026, scientists in 1999 and 2000 had recorded underwater sound at 101 sites in the Davis Sea, Eastern Antarctica. They recorded between 4 December and 10 January. They wanted to count leopard seals by their calls. The recordings captured a total of 38,270 leopard seal calls. As of November 2026, an acoustic survey of the Davis Sea estimated 5,926 leopard seals across 19,820 square kilometres, about 0.31 seals per square kilometre. As of November 2026, a visual survey of the same region and time estimated only 0.006 leopard seals per square kilometre. The authors of the 2013 Davis Sea study state that visual surveys alone are likely to vastly underestimate the population of leopard seals.

As of November 2026, scientists had tagged 22 leopard seals off the Western Antarctic Peninsula to follow their dives and travels. In that study, as of November 2026, the tagged seals dived on average to about 30 metres and for about three minutes. As of November 2026, among the tagged seals, the farthest distance travelled ranged from 46 km to just over 1,669 km. As of November 2026, two tagged adult female leopard seals spent two weeks on ice in the middle of the ocean.

Leopard seals mate in December and early January, and they are believed to mate in the water. A mother leopard seal gives birth to a single pup on the sea ice. Pups are usually born on the ice in November and December. A newborn pup weighs about 30 kilograms or more, and it is nursed for about four weeks. Once weaned, leopard seal pups start hunting krill. Leopard seals may live for 26 years or more.

Words to know

• acoustic: using sound
• estimate: a best guess
• survey: a careful count
• population: a whole group