August 11 is a big day in the Antarctic calendar because it’s World Krill Day. It’s the one day of the year where we turn our attention from all our charismatic favourites like penguins and humpback whales, and we focus our attention on the tiny creatures without whom the Southern Ocean would be an empty place: krill.
Without this humble crustacean, which swarms in vast numbers in the polar seas, the entire Antarctic ecosystem as we know it wouldn’t exist. Krill eat the phytoplankton that blooms in Antarctic waters, helping capture and store atmospheric carbon, and providing food for fish, penguins, seals and whales. They’re the most important Antarctic animal you’ll never see. But humans are taking in increased commercial interest in krill, which are being fished in ever-growing numbers in Antarctica. To learn more about efforts to manage the fishery and protect Antarctic waters, we spoke to Dr Rodolfo Werner, a consultant with the Minderoo Foundation and Antarctic and Southern Ocean Coalition (ASOC), as well as science advisor and board member of the Antarctic Wildlife Research Fund, who has been working on krill for over two decades.
Why fish for krill?
The Antarctic krill, also known as Euphausia superba, grows to about the length of an adult’s finger, making it the perfect size to be eaten by penguins or scooped up in huge quantities by whales. It was until the 1960s during the heyday of industrial whaling, that people started thinking of establishing a krill fishery. The Soviet Union, which was one of the largest whaling nations, sent subsidised fleets to operate in East Antarctica, working on the hypothesis that the commercial exploitation of whales might have produced a ‘surplus’ krill population as a result.
Within a decade, Japan also established its own krill fleet, and the fishery eventually moved towards the patch of the Southern Ocean lying between South Georgia and the Antarctic Peninsula where krill was more abundant. The krill weren’t fished for direct human consumption, and still aren’t. They were harvested to make aquaculture feed for farmers or to make pet food. In more recent years, krill oil has become more important. Thanks to its night levels of Omega-3 fatty acids, Antarctic krill oil is now increasingly marketed as a human health supplement.
‘After some years, scientists studying krill were worried that we weren’t managing the fishery,’ explains Dr Werner. ‘This was the first step to start the discussions that led to the creation of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which is also sometimes called the Krill Convention.’ CCAMLR (pronounced to rhyme with Pamela) was the first international convention to attempt to manage the krill fishery, says Werner, that it came into effect on April 7, 1982 on the day of his birthday.
How krill fishing is managed
As its name suggests, CCAMLR put conservation at the heart of what it was about. ‘It was very novel when it was established because it had two principles: ecosystem-based management and the precautionary principle.’ This was a world away from the brutal tragedy of the commons that was industrial whaling. At that time, a maximum catch limit was also established for Antarctic waters. The idea was to ensure that the fishery could be fully sustainable, with no potential to damage local ecosystems by over-exploiting a particular location.
In the early years of CCAMLR, the idea that krill could even be overfished seemed like a distant prospect. The break-up of the Soviet Union led to the collapse of the krill fishery. ‘When I started working with krill in 2003, the fishery was taking less than 100,000 tonnes of krill a year,’ says Werner. ‘The catch limit was six times that at 620,000 tonnes, which is still the maximum catch limit today.’ The number represents around 1% of the estimated krill population in that area of Antarctica.
In 2025, that catch limit was reached for the first time, triggering the complete closure of the krill fishery. The 620,000 tonnes were taken by traditional trawlers and the so called super trawlers with immense vacuum-equipped nets, operating along the northern part of Antarctic Peninsula: an area that’s a key foraging ground for penguins and whales, as well as being the main destination for Antarctic tourism. Due to the concentrated fishing pattern, the concern has always been always about the reduction of krill availability in certain areas that are key for predators.
The threat of overfishing krill
The problem arises through the recent lapse of one of CCAMLR’s key instruments. Conservation Measure 51-07 was established in 2009 to distribute annual krill catches between four areas — the Antarctic Peninsula, South Orkneys, South Georgia and the South Sandwich Islands — to ensure that the krill never ran the risk of being overfished in any one area. ‘We agreed to this measure in 2009 in order to split the catches, reducing the possibility of krill fishing concentrating in one particular area. The fishery normally moves, starting in the South Orkneys in the summer and then moving to the Antarctic Peninsula. But some years it’s more challenging to fish in the South Orkneys because of the sea ice, so they’ll move earlier to the Peninsula. Then by the middle of the season they’ll reach the maximum for that area and move on again,’ says Werner. ’But if catches reach the maximum, then the fishery will be closed.’
‘CM 51-07 was an interim measure that was supposed to be extended every year or two depending on what was agreed. But what happened in 2024 was that China blocked its extension. As a result, we’ve gone back to the situation where you can fish 620,000 tonnes of krill wherever you want and whenever you want.’ The result of this is that krill catches in the Antarctic Peninsula doubled in the 2024/25 season. This took place exactly at the time of the season when penguins are foraging to feed their chicks while whales gorge themselves on krill to regain body mass after a winter spent fasting in warmer waters.
‘This is what has always been our concern – concentrated fishing and the potential depletion of krill in certain areas,’ says Werner. ‘This isn’t just along the Peninsula but also in the South Orkneys where the fishery operates in very concentrated places where we’re seeing large aggregations of fin whales. That’s the reason why we’re trying to establish catch limits at a smaller scale. In addition to that, monitoring will be key so as to check how krill predators are doing in those areas. We can best do this with the penguin colonies because they’re the easiest to monitor – and if things aren’t going right then we can change the fishery management.’
A Marine Protected Area for the Antarctic Peninsula?
The biggest opportunity for conservation would be the establishment of a Marine Protected Area (MPA) along the Antarctic Peninsula. In 2016, CCAMLR voted unanimously to do exactly that for the Ross Sea region. At the stroke of a pen, this became the largest protected stretch of ocean in the world, covering an area of just over 2 million square kilometres, or more than three times the size of California. No krill is fished there, although there is an area where research krill fishing could take place. After 6 years of preparation, in 2018 the governments of Argentina and Chile presented a proposal for an MPA in the area what is called Domain One, covering the Antarctic Peninsula and the South Orkney Islands. The idea has yet to be accepted by the CCAMLR Commission.
‘In 2024, there was a proposal to bring the development and management of the fishery and the creation of the MPA into a single plan,’ says Werner. Unfortunately, the discussion at the CCAMLR meeting went badly, and in the end, China blocked any further progress. Further complications are added by the Russian war in Ukraine, as both are also CCAMLR members. For the time being, the plans for both the MPA and managing the catch limits are on hold.
Despite this, as a veteran of these diplomatic wranglings, Werner refuses to be pessimistic. ‘We hope we’ll see some action at the forthcoming CCAMLR meeting in October this year.
‘The question is whether China is really interested in going over the trigger limit this year?’ he says, referring to the current catch limit. Any proposal to increase the krill catch over the magic number of 620,000 tonnes will automatically trigger the division of that catch into smaller scale units, as agreed by CCAMLR many years ago. What’s more, there would be further limits for summer and winter fishing. ‘With that, you’re reducing the risk of fishing in a very concentrated way,’ as well as reducing any possible ecosystem impacts.
CCAMLR, he reminds me, works on consensus. ‘Argentina and Chile, who developed the proposal for the MPA in the Antarctica Peninsula might not allow an increase in the krill fishery unless the MPA is established.’
Where does this leave the poor krill? The wheels of international diplomacy often turn very slowly, but despite the increase in the krill fishery, the Antarctic Peninsula is also home to one of the most optimistic conservation stories of modern times. When CCAMLR was set up in the early 1980s, factory ships still plied polar waters hunting whales to the brink of extinction. In the four decades since the moratorium on whaling, the global population of humpback whales has recovered to over 90% of its pre-whaling numbers – and the Antarctic Peninsula has become one of the world’s best whale-watching destinations.
It took a long time for the world to wake up to the threat to whales, but scientists and conservationists are already in the corner fighting for krill, just as their importance in the Antarctic ecosystem is becoming better known to the world at large.
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