Red List of South African Species

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Least Concern (LC)
Assessors: Luis Hückstädt
Facilitators: Lloyd Lowry Heidi Ahonen Caroline Pollock Federica Chiozza Alessia Battistoni
Reviewers: Peter Boveng

Rationale

Due to its widespread occurrence, large population size and lack of major threats, the Weddell Seal is classified by IUCN as Least Concern.

Distribution

Circumpolar and widespread in the Southern Ocean, Weddell Seals are the world’s southern-most breeding mammal and occur in large numbers on fast ice, right up to the shoreline of the Antarctic continent. They also occur offshore in the pack ice zone north to the seasonally shifting limits of the Antarctic Convergence. A small population lives all year on South Georgia. Weddell Seals are present at many islands along the Antarctic Peninsula that are seasonally ice-free. Vagrants have been recorded in many areas north of the Antarctic in South America, New Zealand and southern Australia (Kooyman 1981, Rice 1998).

Population trend

Trend

The global population of Weddell Seals has been variously estimated at 200,000 to 1,000,000 individuals (Erickson and Hanson 1990, Southwell et al. 2012), although there is large uncertainty in these figures. Weddell Seals are a widespread species and population assessments are very difficult and expensive to conduct, and are therefore infrequently undertaken. Southwell et al. (2012) reported on results from the Antarctic Pack-Ice Seals program which conducted extensive surveys during 1996–2001. They estimated 633,000 Weddell Seals in two of their survey sectors. In the third sector fast ice was not surveyed and Weddell Seal abundance was not estimated.

Threats

At present, there are no immediate or significant threats to the Weddell Seal.

The potential effects of global climate change on Antarctic seals are largely unknown. Sea ice provides habitat used for pupping, resting, avoidance of predators and access to preferred foraging areas. Learmonth et al. (2006) suggest that Weddell Seal numbers may decline with increasing temperatures if Antarctic sea ice is significantly reduced. In contrast, Proffit et al. (2007), reported that the localized cooling and increased sea ice extent in the Ross Sea was associated with decreased reproduction and lower weaning mass of Weddell Seals in McMurdo Sound. Further, the fact that some populations breed on land (e.g., at South Georgia), could demonstrate an ability in the species to colonize different environments, although the extent of such plasticity is uncertain. Thus, the overall effects of global climate change on Weddell Seals are unknown.

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 approach by people in small boats and on land or ice, on Weddell 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 vessel passage through ice fields. Currently there are no reports of significant fisheries interactions. However, the development of new fisheries in Antarctic waters, particularly one targeting the Antarctic Toothfish, could have an impact on Weddell Seal nutrition, and potential operational interactions should be considered in the management plans.

Uses and trade

Weddell Seals served as an important source of food for men and dogs throughout the early periods of Antarctic exploration (Stirling 1971) until the final removal of dogs from the continent in the 1990s. Local populations no doubt suffered declines from these harvests, but the Murdo Sound population has recovered in the 30 years since harvests ended in the 1980s (Testa and Siniff 1987).

Conservation

The Weddell Seal is not listed as endangered or threatened under any national Red List. They are protected by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals, and any future commercial harvest would be regulated by those international agreements.

References 

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