Antarctic krill supports not only a unique marine ecosystem but also one of the largest fisheries in the Southern Ocean. As outlined in our previous article on krill’s ecological role, these small crustaceans form the foundation of the Antarctic food web. Each year, hundreds of thousands of tons are harvested, mainly in the southwest Atlantic sector. The fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which aims to balance economic use with the protection of marine ecosystems.
Unlike many fisheries, krill management follows an ecosystem-based approach. This means that catch limits are set not only to protect krill itself, but also the many species that depend on it, including penguins, seals, and whales. All vessels are required to carry scientific observers who monitor catches and collect biological data. Currently, the total annual catch limit for the main fishing area is around 620,000 tons, although actual catches have often been lower in the past, with recent seasons approaching this limit.
One important concept in this context is the so-called “trigger level.” This is a precautionary catch threshold that limits how much krill can be taken before stricter spatial management is required. In practice, however, fishing effort tends to cluster in areas where krill is most abundant, which can also be key feeding grounds for predators.
Since 2024, however, key spatial management measures have lapsed after CCAMLR members failed to reach agreement on their renewal. As a result, the fishery continues to operate under an overall catch limit, but without rules that distribute fishing effort across different areas. This has increased concern that fishing could become more concentrated in ecologically sensitive regions.
Recent research highlights how closely fishing activity and wildlife can overlap. A study using acoustic data collected directly from krill fishing vessels showed that whales, penguins, and seals are often present near active fishing operations, with clear seasonal and regional patterns.
The study also indicates that some existing protection measures may not always work as intended. Restrictions designed to reduce interactions with breeding penguins in one area can shift fishing activity elsewhere, potentially increasing encounters in regions that are less well monitored.
Another concern is bycatch, the unintentional capture of non-target species. Although krill nets are designed to target small organisms, they can also catch fish, particularly at early life stages. A recent study combining visual identification with genetic methods found that fish diversity in krill catches has been underestimated, identifying more species than previously recorded and highlighting challenges in accurate monitoring.
While bycatch levels in the krill fishery are generally low compared to many other fisheries, these findings underline the importance of improving observation and reporting. They also point to broader uncertainties in how fishing interacts with the wider ecosystem.
Scientists have also raised concerns about how current management responds to environmental change. Krill populations can vary strongly from year to year, and climate-related shifts in sea ice and ocean conditions may influence their distribution and reproduction. Current catch limits are largely based on historical data and do not fully account for this variability.
As a result, researchers are calling for more adaptive approaches that better reflect the complexity of the Southern Ocean ecosystem. Proposed improvements include integrating ecological data more directly into management decisions and using fishing vessels themselves as platforms for data collection.
Krill fishing in the Southern Ocean remains a tightly regulated industry, but it also sits at the center of an ongoing scientific and political debate. Understanding how fishing, wildlife, and a changing environment interact will be key to ensuring that this small crustacean continues to support one of the most remarkable ecosystems on Earth.
Léa Zinsli, PolarJournal