Krill under pressure: how fishing fleets are competing with penguins and whales

If you take Omega-3 supplements, there’s a good chance you’ve unknowingly dipped your hand into the Southern Ocean’s food chain. The key ingredient in many fish oil capsules, krill, plays a pivotal role in the Antarctic marine ecosystem, and new research shows that our growing appetite for these tiny crustaceans may be putting stress on the animals that rely on them most.

Antarctic krill, Euphausia superba, may be small at just 1 to 6 centimetres in length, but they are mighty. These translucent, shrimp-like creatures gather in dense swarms that can contain up to 30,000 individuals per cubic metre. They feed primarily on phytoplankton and in turn feed an entire ecosystem, from penguins and seals to baleen whales fattening up for their long migrations.

But krill are no longer just on the menu for marine predators. They’ve become an increasingly lucrative target for industrial fishing, with much of the catch used for animal feed and dietary supplements. Now, scientists are beginning to ask: what happens when industrial fishing vessels and krill predators compete for the same food source?

A new study published in Proceedings of the National Academy of Sciences takes a closer look at that question, using an innovative approach. By analysing over 30,000 hours of acoustic recordings collected over six years by three krill fishing vessels, researchers from Germany’s Alfred Wegener Institute (AWI) and Norway’s Institute of Marine Research were able to track when and where fishing ships and krill predators cross paths.

“During such encounters, ships and krill predators pursue the same krill swarms,” says Dominik Bahlburg from the Alfred Wegener Institute.

“This allowed us to systematically analyse the spatial and temporal dynamics of this competition in order to identify locations and time periods where the interaction between the two groups is particularly intensive.”

The team used AI and acoustic segmentation models to filter out diving signals from whales, seals, and penguins recorded by the ships’ echo sounders.

What emerged were distinct seasonal patterns showing how different predators overlapped with the krill fishing fleet in specific regions. Take the South Orkney Islands, for instance.

“The South Orkney Islands seem to be a real hotspot for encounters with penguins,” says Bahlburg. Fishing vessels frequently encountered penguins here during the summer — right in the middle of their breeding season.

What’s more, the study suggests that voluntary restrictions on fishing near penguin colonies along the Antarctic Peninsula may have simply shifted the pressure elsewhere, rather than reducing it overall.

One finding particularly surprised the team: penguins and fur seals were just as likely to encounter krill fishing vessels in winter as in summer. Until now, winter fishing had been considered less risky to wildlife, as animals tend to be more dispersed and less tethered to breeding grounds.

“However, the fact that the animals are now also encountering ships so frequently at this time may require a reassessment of this development,” Bahlburg notes.

Whales, meanwhile, were rarely observed near fishing vessels in the South Orkneys, but in the autumn months off the Antarctic Peninsula, competition between fisheries and whales was intense. This is the season when whales are bulking up on krill before their migrations to breeding grounds.

“Remarkably, these patterns were quite stable for seals, penguins and whales over a six-year period,” adds Sebastian Menze from the Norwegian Institute of Marine Research.

That stability suggests this new method — using acoustic data from fishing ships paired with machine learning — could become a powerful tool in managing the krill fishery and mitigating its ecological impact.

Best of all, it’s cheap and scalable. Since echo sounders are already a standard part of fishing vessels, the data can be collected with minimal additional cost.

“We are expanding the potential uses for ecological questions and demonstrating new, cost-effective ways in which fishing vessels can actively contribute to krill fishery management,” emphasises Bettina Meyer, from the AWI.

This acoustic approach offers something rare in marine research: high-frequency, year-round data from some of the ocean’s most remote areas.

As the Southern Ocean warms and human demand for krill continues to grow, these insights could help us better protect one of the planet’s most vital and vulnerable ecosystems.