Antarctic Seals: Conservation Efforts Through the Antarctic Seals Convention

Antarctica’s icy waters are home to some of the most resilient marine mammals on the planet – seals. From the elusive Ross seal to the powerful leopard seal, these species have survived extreme conditions for millennia. But they haven’t always been safe from human activity. Centuries of unregulated hunting nearly wiped out several Antarctic seal populations. In response, the international community came together to create a legal framework designed to protect these animals. That framework is the Convention for the Conservation of Antarctic Seals (CCAS), a 1972 treaty that remains a cornerstone of Antarctic wildlife protection today.

Why the seals convention was needed 🔗

When Captain James Cook reached South Georgia in the late 18th century, he reported vast numbers of fur seals along its shores. That report essentially triggered a wave of commercial sealing that would last well over a century. Hunters descended on the Antarctic and sub-Antarctic regions in pursuit of seal pelts, and the killing was relentless – bringing many species to the brink of extinction. By the early 1820s, Antarctic seal populations had already been severely depleted.

In the decades that followed, some conservation efforts emerged. The 1964 Agreed Measures for the Conservation of Antarctic Fauna and Flora offered initial protections, but they applied mainly to land-based species and didn’t adequately cover seals found on the high seas. A Norwegian-led sealing expedition in the early 1960s further highlighted the vulnerability of seal species that fell outside existing protections. Recognising this gap, the Antarctic Treaty Consultative Parties developed a dedicated convention – the CCAS – which was signed in London on 1 June 1972 and entered into force in 1978.

The treaty’s stated purpose was to promote protection, scientific study, and the rational use of Antarctic seals while maintaining ecological balance in the Antarctic ecosystem. It was essentially a precautionary measure, put in place even before large-scale commercial sealing resumed, to ensure that history would not repeat itself.

Species covered under the convention 🔗

The CCAS applies to all seas south of 60° South latitude and covers six key seal species found in Antarctic waters:

Southern elephant seal (Mirounga leonina) – the largest of all seal species, known for the males’ distinctive trunk-like noses. These massive animals can weigh up to 4,000 kilograms and dive to extraordinary depths in search of fish and squid.

Leopard seal (Hydrurga leptonyx) – a top predator in the Antarctic food chain. Leopard seals are known for their powerful jaws and varied diet, which includes fish, krill, penguins, and even other seals.

Weddell seal (Leptonychotes weddellii) – a species that lives farther south than any other mammal. Weddell seals are relatively flexible in their diet, feeding on fish, krill, and squid, which makes them somewhat more adaptable to environmental changes.

Crabeater seal (Lobodon carcinophagus) – despite their name, these seals don’t actually eat crabs. Their diet consists almost entirely of Antarctic krill, making them highly dependent on krill availability.

Ross seal (Ommatophoca rossii) – one of the rarest and least studied Antarctic seals. Ross seals are solitary animals found primarily in the dense pack ice, making population assessments particularly difficult.

Southern fur seals (Arctocephalus sp.) – the only “eared seals” in the Antarctic, once hunted almost to extinction for their dense, valuable pelts. Their populations have made a remarkable recovery since protections were established.

Regulations on catch limits and seasonal restrictions 🔗

The convention doesn’t impose a blanket ban on all seal-related activities. Instead, it establishes a regulated framework. The CCAS Annex sets permissible catch limits for certain species while completely prohibiting the killing or capture of Ross seals, southern elephant seals, and southern fur seals. For species where limited take is allowed, the convention specifies annual catch ceilings.

The treaty also divides Antarctic waters into six sealing zones (based on longitude), and each zone is subject to a rotating closure system. Zones are closed in numerical sequence from 1 September through the end of February each year. This seasonal restriction ensures that seals are not disturbed during critical breeding and pupping periods. Additionally, contracting parties agreed to take steps to ensure their nationals refrain from killing or capturing seals in the water, except in limited quantities for scientific purposes.

Sustainable management and the role of research 🔗

Science sits at the heart of the CCAS. The convention explicitly requires that decisions about seal management be based on the best available scientific and technical evidence. This principle is enforced through a close partnership with the Scientific Committee on Antarctic Research (SCAR), which plays a central advisory role.

The permit system 🔗

Under the convention, each contracting party is required to adopt laws and a permit system to implement the treaty’s provisions. Any killing or capture of seals must be authorised through permits, and the details of these activities – including the number and species of seals taken, the location, and the methods used – must be reported to both SCAR and other contracting parties.

Permits can be issued for three specific purposes: to provide food for people or sled dogs, to supply specimens for scientific research, and to provide specimens for educational or cultural institutions. This permit system ensures that even limited human interaction with seal populations is carefully tracked and controlled.

Monitoring through SCAR 🔗

SCAR’s responsibilities under the convention are substantial. It monitors catch data, advises on whether permissible limits are being approached, and can alert the treaty depositary (the United Kingdom) if it estimates that catch limits for any species are likely to be exceeded during a sealing season. When this happens, each contracting party must take measures to prevent further killing or capture of that species until a collective decision is made. SCAR can also request technical assistance from the Food and Agriculture Organization of the United Nations (FAO) when necessary.

Contracting parties are required to submit annual statistical summaries – by zone and month – covering all seals killed or captured. This data includes vessel information, crew numbers, days of operation, and species-specific counts for both adults and pups. This level of reporting transparency is essential for tracking population trends and adjusting management strategies accordingly.

International collaboration for seal conservation 🔗

One of the convention’s greatest strengths is the way it fosters cooperation among nations active in the Antarctic. Currently, 17 countries are parties to the CCAS, including Argentina, Australia, Chile, France, Germany, Japan, Norway, Russia, the United Kingdom, and the United States. New Zealand has signed but not yet ratified the convention.

Review meetings and adaptive management 🔗

The convention requires contracting parties to meet at least every five years to review its operation. The first major review took place in 1988, ten years after the treaty entered into force. These periodic reviews allow parties to assess whether the convention’s measures remain adequate, consider amendments to the Annex, and respond to new scientific findings.

Importantly, the convention includes a provision for emergency action. If SCAR reports that harvesting of any seal species is having a significantly harmful effect on overall stocks or the local ecosystem, any contracting party can request an immediate meeting. The convention also allows for the establishment of a dedicated scientific advisory committee – by a two-thirds majority – if commercial sealing ever reaches significant levels.

Connection to the broader Antarctic Treaty System 🔗

The CCAS doesn’t operate in isolation. It is part of the larger Antarctic Treaty System (ATS), which includes the 1959 Antarctic Treaty, the 1980 Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR), and the 1991 Protocol on Environmental Protection. Together, these agreements create a comprehensive governance framework for Antarctica.

The CCAS specifically paved the way for CCAMLR by establishing the precedent that high-seas resources in the Antarctic could be governed through multilateral agreements. CCAMLR, in turn, takes an ecosystem-based approach to managing marine resources – including krill – which directly affects the food supply of many seal species.

Challenges in marine mammal conservation 🔗

While the CCAS has been remarkably successful in preventing commercial sealing – no significant commercial seal hunting has occurred in Antarctica since the convention was established – the threats to Antarctic seals have shifted. Today, the biggest concern is climate change.

Climate change and sea ice loss 🔗

For species like the crabeater seal, which depends on sea ice for breeding, resting, and access to food, the biggest threat is considered to be climate change and the resulting changes in sea ice cover. Sea ice loss directly reduces available habitat and also disrupts krill populations – the primary food source for several seal species.

Research has shown that different species will respond to warming temperatures in different ways. Crabeater seals, with their specialised krill diet, are considered more vulnerable than Weddell seals, which have a more diverse diet and are influenced more by non-climate factors. This means conservation strategies need to account for species-specific vulnerabilities rather than applying a one-size-fits-all approach.

The krill crisis 🔗

Krill is the foundation of the Antarctic marine food web, and its availability directly affects seal survival. Research from the British Antarctic Survey has found that rapidly rising sea temperatures correlate with declining fur seal populations, likely because warmer waters reduce krill abundance in key foraging areas. At Bird Island in South Georgia, fur seal populations peaked around 2009 and have since declined by roughly 7% per year, reaching their lowest numbers since the 1970s.

The decline is especially concerning because Antarctic fur seals are considered a key indicator species – their population trends reflect the broader health of the Antarctic marine ecosystem. Meanwhile, an isolated population of fur seals in the South Shetland Islands is declining so sharply that NOAA researchers have proposed listing it as critically endangered under the IUCN Red List. Losing this population would also mean losing crucial genetic diversity that the entire species may need to adapt to future climate conditions.

Monitoring gaps 🔗

A persistent challenge in Antarctic seal conservation is the difficulty of conducting accurate population censuses. The remoteness of Antarctica, the vast areas involved, and the fact that many seal species spend much of their time at sea or on inaccessible pack ice make comprehensive monitoring extremely difficult. Without reliable baseline data, detecting population changes – especially gradual ones – becomes nearly impossible until the decline is already severe.

Emerging technologies like satellite-based surveys and improved acoustic monitoring are beginning to help, but significant data gaps remain. The CCAS framework supports research activities, but the practical challenges of conducting fieldwork in one of the harshest environments on Earth mean that many Antarctic seal populations remain poorly understood.

Looking ahead 🔗

The Convention for the Conservation of Antarctic Seals represents one of international law’s early success stories in preventive conservation. It stopped commercial sealing before it could restart, and seal populations have recovered significantly as a result. But the convention was designed primarily to address the threat of over-hunting – not climate change. As environmental conditions in Antarctica continue to shift, the question is whether existing frameworks like the CCAS, along with CCAMLR and the broader Antarctic Treaty System, can adapt quickly enough to protect seal populations from threats that weren’t envisioned when the treaty was written over 50 years ago.

What do you think? Can international treaties designed decades ago adequately protect wildlife from modern threats like climate change? And what role should krill fishery management play in safeguarding the future of Antarctic seal species?

References

1. https://www.umweltbundesamt.de/en/convention-for-the-conservation-of-antarctic-seals
2. https://www.ats.aq/e/related.html
3. https://en.wikipedia.org/wiki/Convention_for_the_Conservation_of_Antarctic_Seals
4. https://sedac.ciesin.columbia.edu/entri/texts/antarctic.seals.1972.html
5. https://iea.uoregon.edu/treaty-text/2808
6. https://www.ccamlr.org/en/organisation/convention-history
7. https://documents.ats.aq/ATCM42/att/ATCM42_att079_e.pdf
8. https://www.bas.ac.uk/media-post/new-threat-to-antarctic-fur-seals/
9. https://www.fisheries.noaa.gov/feature-story/isolated-population-antarctic-fur-seals-could-save-species-theyre-disappearing