Antarctic Seals

True seals are sometimes called crawling seals, as they are unable to propel their bodies forward on land using their hind and fore flippers like eared seals can. Instead, they move a little like a caterpillar, shuffling slowly over rocks, ice and snow. However, they are expert swimmers and divers, and the holds the world record for the deepest dive, to a depth of almost 7000 feet (>2,133 meters).

True seals can be further subdivided into tribes based on shared characteristics. The Ross seal, crabeater seal, leopard seal and Weddell seal are the sole members of the lobodintini tribe. They all have lobodontine or lobed teeth, which act as sieves and allow them to filter their food. Southern elephant seals, along with their northern counterparts, are the only members of the miroungini tribe.

While eared seals are marine mammals that live predominantly at sea, they haul out on land to breed and rest. They are able to move more efficiently over land than true seals, using their hind and fore flippers to lope or gallop at speeds of up to 12.5 miles per hour (20 kilometers per hour). Their powerful flippers also allow them to move and maneuver quickly underwater.

Another identifying feature of eared seals is the elongated shape of their heads, with a slender, pointed muzzle similar to a dog’s snout.

There is only one type of eared seal living in the Antarctic, the Antarctic fur seal. 

Signed on 1 June 1972 and entered into force in 1978, CCAS provided protection for all six Antarctic seal species in the waters south of 60 degrees South.

CCAS proved successful in allowing seal populations to recover and thrive after decades of commercial exploitation in the Antarctic. 

Read the Convention.

The main purpose of the Protocol is to ensure that environmental protection is central to the planning and conduct of all activities in Antarctica and the Southern Ocean. It identifies the Antarctic environment as a wilderness with intrinsic aesthetic and scientific value, which must be a “fundamental consideration” of all activities in the area.

Read the Protocol. 

With 27 Member nations, and an additional 10 countries acceding to the Convention, CCAMLR is charged with regulating and managing human activity, such as fisheries and scientific research, in the Southern Ocean. These decisions must be informed by a precautionary, ecosystem-based approach, with conservation as the primary goal. 

This is important for seals, as their primary food source, Antarctic krill, is a popular target for fisheries. 

CCAMLR’s role in ensuring the conservation of Antarctic krill, crustaceans, and small fish is vital to the survival of seal populations in the Southern Ocean. 

Learn more about CCAMLR.

ASOC advocates strongly for a representative network of MPAs in the Southern Ocean, starting with existing proposals in East Antarctica, the Weddell Sea, and the Antarctic Peninsula.

If adopted, these MPAs will help create the conditions for Antarctic seals to survive and thrive in the face of a rapidly changing environment.

Despite overwhelming scientific evidence to support the establishment of new Antarctic marine protected areas, only 5% of the Southern Ocean has been protected. 

Learn more about our ongoing campaign for Antarctic Marine Protected Areas. 

Read ASOC policy papers and reports to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

These silent killers include fishing nets, lines and hooks, and fish traps, which continue to “fish”, and which seals can become entangled in, often leading to a slow, painful death. 

In the Southern Ocean, nearly 850 miles (1363 kilometers) of long line was abandoned, lost or discarded in only two fishing seasons. Fishing line takes around 600 years to break down. When it finally does, it disintegrates into harmful microplastics, which can be ingested by fish and crustaceans, and eventually marine mammals and humans.   

Download our ghost gear infographics.

Photo credit: NOAA

Source: Richardson et al., (2022). Global estimates of fishing gear lost to the ocean each year. Science Advances. DOI:10.1126/sciadv.abq0135

Find out more.

Microplastics come from a range of sources, such microbeads from personal hygiene products, and fibers from laundry water. They can also result from the breakdown of larger plastic items, such as abandoned, lost, or discarded fishing gear,  other sources of shipping waste, straws, or bottles.

Scientific research has found microplastics in Antarctic snow, the waters of the Southern Ocean, and in zooplankton, such as Antarctic krill and salps. Given the important role of zooplankton as the foundation of the Antarctic food web – particularly the keystone species krill – some researchers have expressed concerns that microplastics could be transferred up the food web, with harmful effects on species such as penguins and seals. This is an area of current research.

Download ASOC information paper about the discharge of waste water in Antarctic Treaty waters.

Download our plastic pollution infographic.

Download our microplastics from marine paints infographic

Sources:

Merrill et al., (2023). Microplastics in marine mammal blubber, melon, & other tissues: Evidence of translocation, Environmental Pollution, Volume 335, 2023, https://doi.org/10.1016/j.envpol.2023.122252

Caruso et al., (2022) Plastic occurrence, sources, and impacts in Antarctic environment and biota, Water Biology and Security, Volume 1, Issue 2, 2022, 100034,

https://doi.org/10.1016/j.watbs.2022.100034.

Sea ice is a vital part of the Antarctic ecosystem, and essential to the lifecycle of all Antarctic seals. Seals haul out on its surface to rest, molt, and pup, while its underside provides shelter for larval krill, an important food source for most seals in the Southern Ocean. 

Antarctic winter sea ice has been declining since 2016, reaching record low levels in 2023, for the third time in only six years. The exact impacts of reduced sea ice on seal populations are unknown, which is why ASOC encourages Antarctic decision-makers to adopt a precautionary approach to Antarctic ecosystem management. 

Read more about our work. 

Read a report on Antarctic sea ice from the World Meteorological Organization

Read the British Antarctic Survey briefing.

Underwater noise from shipping has a significant impact on marine wildlife, interfering with successful communication, causing stress and hearing damage, and reducing resilience to other threats.

As the number of tourism and shipping vessels increases, particularly on the Antarctic Peninsula, the potential impact on seal populations increases. 

Sources: 

Cziko et al. (2020). Weddell seals produce ultrasonic vocalizations. Journal of the Acoustical Society of America. 1 December 2020; 148 (6): 3784–3796. https://doi.org/10.1121/10.0002867

Erbe et al. (2019). The effects of ship noise on marine mammals  – A review. Sec. Marine Conservation and Sustainability
Volume 6 – 2019  https://doi.org/10.3389/fmars.2019.00606

Halliday et al. (2020). Underwater noise and Arctic marine mammals: review and policy recommendations. Environmental Reviews. 28(4): 438-448. https://doi.org/10.1139/er-2019-0033

Heise, K. (2016). The Effects of Underwater Noise on Marine Animals. Paper presented at the SNAME Maritime Convention, Bellevue, Washington, USA, November 2016.