Hydrurga leptonyx 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Phocidae

Scientific Name: Hydrurga leptonyx (de Blainville, 1820)
Common Name(s):
English Leopard Seal
Phoca leptonyx de Blainville, 1820

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2015-01-20
Assessor(s): Hückstädt, L.
Reviewer(s): Kovacs, K.M.
Facilitator/Compiler(s): Lowry, L., Ahonen, H., Pollock, C.M., Chiozza, F. & Battistoni, A.
The most recent circumpolar estimate of Leopard Seal abundance indicates a total population of more than 35,000 individuals, but this is likely a substantial underestimate. There is no indication of a declining trend in the population, although abundance estimates have considerable uncertainty around them and consequently trend is unknown. Leopard Seals depend on sea ice for reproduction and at some time in the future they could be adversely affected by a reduction in sea ice due to continued climate warming. Leopard Seals are currently a widespread and abundant species that does not qualify for any of the IUCN threatened categories, and they should be listed as Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Leopard Seals are widely distributed in Antarctic and sub-Antarctic waters of the Southern Hemisphere, occurring from the coast of the Antarctic continent northward throughout the pack ice and at most sub-Antarctic islands. There is a seasonal presence of juveniles at Kerguelen and Macquarie Islands with the greatest numbers being sighted in September and October (Rounseveld and Eberhard 1980, Borsa 1990). Vagrants regularly reach warm temperate latitudes. Leopard Seals haul out on ice and on land, often preferring ice floes near shore when they are available (Kooyman 1981).
Countries occurrence:
Antarctica; French Southern Territories; Heard Island and McDonald Islands; South Georgia and the South Sandwich Islands (South Georgia, South Sandwich Is.)
Australia; Bouvet Island; Brazil; Chile; Cook Islands; Falkland Islands (Malvinas); New Zealand; Pitcairn; Saint Helena, Ascension and Tristan da Cunha; South Africa
FAO Marine Fishing Areas:
Atlantic – southwest; Atlantic – Antarctic; Indian Ocean – Antarctic; Pacific – southeast; Pacific – southwest; Pacific – Antarctic
Additional data:
Estimated area of occupancy (AOO) - km2:21547648Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:34454727
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):3Lower depth limit (metres):304
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The Leopard Seal is a widespread species and, similar to the other Antarctic seals that inhabit the pack ice, population assessments are very difficult and expensive to conduct and therefore undertaken infrequently. Published global population estimates from many decades ago range from 100,000-300,000 (Scheffer 1958) up to 220,000-440,000 animals (Laws 1984). However, these early estimates were based on very limited sampling and were highly speculative. An analysis of ship and aerial sighting surveys carried out around the continent between 1968 and 1983 provided a point estimate for global Leopard Seal population size in the pelagic pack ice of the Southern Ocean of 300,000 animals (Erickson and Hanson 1990). The most ambitious and coordinated effort to date, the Antarctic Pack-Ice Seal (APIS) project, conducted aerial and shipboard surveys around the continent during 1996-2001, and also included deployment of satellite-linked dive recorders to investigate haulout behaviour. APIS surveys resulted in an estimate of 35,500 (95% CL 10,900-102,600) Leopard Seals in the surveyed areas (Southwell et al. 2012). All estimates have considerable uncertainty associated with them, and only very large changes in Leopard Seal population size could be confidently detected from repeated surveys (Southwell et al. 2008).
Current Population Trend:Unknown
Additional data:
Number of mature individuals:18000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Adult male Leopard Seals are 2.8 to 3.3 m long and weigh up to 300 kg. Adult females are 2.9 to 3.6 m, with very large animals possibly reaching 3.8 m, and weights of 260 to upwards of 500 kg. Pups are 1.0 to 1.6 m in length and weigh 30 to 35 kg at birth. The age at sexual maturity is probably four years for females and 4.5 years for males. Longevity is estimated to be over 26 years (Kooyman 1981, Rogers 2009).

At sea and on the ice, Leopard Seals tend to be solitary. Pups are born on sea ice from early November to late December and the period may be as long as early October to early January (Southwell et al. 2003). Births at South Georgia occur from late August to the middle of September. Pups are probably weaned at four weeks old, and female oestrous occurs at or shortly after weaning. Unlike Crabeater Seals, male Leopard Seals do not haul out with female-pup pairs. Mating is believed to occur in the water, but has never been observed.

Leopard Seals are well known for preying upon penguins. However, their diet is in reality highly varied and changes with seasonal and local abundance of prey. Leopard Seals will consume krill, fish, squid, penguins, a variety of other types of seabirds, and juvenile seals including Crabeater, Southern Elephant and Fur Seals (Rogers 2009, Southwell et al. 2012). In the case of Antarctic Fur Seals, it has been proposed that predation of Leopard Seals on pups might have a significant role in driving population dynamics of the prey species in certain areas (Schwarz et al. 2013). Most prey are caught in the water. Penguins are usually held in the Leopard Seal's teeth by one end and slung in an arc with a rapid snap of the head and neck and smashed on the surface of the water until they are torn open. Smaller pieces are then swallowed. Young, newly fledged naïve penguins are most vulnerable, but adult birds are taken as well. Leopard Seals patrol and regularly station themselves just off Penguin colonies and wait to ambush and chase animals transiting to and from the colonies (Rogers and Bryden 1995).  Krill may be a seasonally important prey (Lowry et al. 1988).

There have been few studies of Leopard Seal diving. Two seals tagged with satellite-linked dive recorders dove mostly to 10-50 m, and the deepest dive recorded was 304 m (Nordøy and Blix 2009).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):10.4
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Small numbers of Leopard Seals have been taken for research purposes and some were previously killed for dog food, but otherwise there is no current or past significant catch of this species (Reijnders et al. 1993).

Threats [top]

Major Threat(s): There are currently no major threats from human activity within the species’ normal range. 

Learmonth et al. (2006) list the effects of global climate change on Leopard Seals as unknown. However, loss of sufficient areas of pack ice habitat suitable for pupping, resting and avoidance of predators, and availability of preferred prey such as Penguins, other Seals, Krill and fish that might all possibly decline, could effect Leopard Seals directly or indirectly to an unknown degree. The effects of loss of large amounts of ice on the Antarctic continent, general climate warming, or sea level rises, on Antarctic ocean circulation and productivity and on Antarctic marine resources such as Seals are unknown. Siniff et al. (2008) suggested that similar to Crabeater Seals, Leopard Seals would be less affected by changes in sea ice than Ross or Weddell Seals.

Two species of Antarctic ice seals, Leopard and Crabeater, have tested positive for antibodies to canine distemper virus (CDV). The effects of an outbreak of this or other diseases on Leopard Seals either as a disease within this species, or repeatedly transmitted to it from an outbreak in a prey species such as the Crabeater Seal, are unknown. Leopard Seals are generally solitary except when females attend their pup or when pairs mate, so transmission of disease within the species would likely be slow or only seasonally significant. CDV is believed to have arrived in the Antarctic with sled dogs before the advent of vaccines. A mass mortality of Crabeater Seals occurred in 1955, with many animals displaying viral illness symptoms prior to death, but the exact cause of death is unknown (Bengtson and Boveng 1991).

Seasonal tourism in the Antarctic and Sub-Antarctic has increased steadily in the last 30 plus years, and is currently at all-time high levels. The effects of increased vessel noise, disturbance from vessels passage, and close approaches by people in small boats and on land on Leopard Seal behaviour, distribution and foraging are unknown. There is also a risk of injury to a small number of animals from collision with boats or crushing from large vessels passing through ice fields.

There are no reports of significant fisheries interactions. Commercial harvest of Krill may pose direct or indirect threats to Leopard Seals, if conducted on a large scale.

Conservation Actions [top]

Conservation Actions: The Leopard Seal is not listed as endangered or threatened on any national Red List. Under the Antarctic Treaty's Convention for the Conservation of Antarctic Seals, the global quota set for Leopard Seals is 12,000 animals annually, but currently there is no harvesting.

Citation: Hückstädt, L. 2015. Hydrurga leptonyx. The IUCN Red List of Threatened Species 2015: e.T10340A45226422. . Downloaded on 21 September 2018.
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