This student story was published as part of the 2025 NASW Perlman Virtual Mentoring Program organized by the NASW Education Committee, providing science journalism experience for undergraduate and graduate students.
Story by Amelia Macapia
Mentored and edited by Katherine Kornei
In polar waters, tiny organisms called Antarctic krill surge by the billions, stretching over kilometers in orange-brown clouds. As the biggest biomass swarms on Earth, these animals support Antarctic food webs and the feeding behavior of apex predators including whales, seals, and penguins. They also play a major role in atmospheric and carbon sequestrations, cycling carbon-rich materials between surface waters and ocean depths.
But commercial vessels can now maneuver more easily through the Southern Ocean in search of the valuable krill (Euphausia superba). In an environment already warming fast, booming krill fisheries are raising a new set of concerns about polar ecology. A recent study, led by Dominik Bahlburg of the Alfred Wegener Institute, reveals how krill-dependent predators and vessels are wrestling in time and space for the same high-density swarms.
With Norway and China emerging as the biggest players in the global krill industry, the guitar pick-sized animals are processed into pills that flush the flesh of farmed fish to drive up their commercial value. Pharmaceutical demand is also growing for omega-3 supplements and fish oil. It’s a fishery that’s serving wealthy nations, and is not addressing food security, says ecologist Matthew Savoca at Stanford University’s Hopkins Marine Stations, who did not participate in the study.
Immense technical advancements have also propelled krill extraction. “The industry has become incredibly efficient,” says Bahlburg. Vessels actively search for and follow the krill swarms, with cylindrical nets attached to suction systems that continuously pump krill on board. At the cutting edge, fleets can now harvest staggering quantities. During the 2023-2024 season, fisheries engulfed 498,350 tons of krill, the largest harvest since catch data collection began.
In an environment of extremes, Krill management has been challenging, with the total krill stock estimated only twice in 25 years. Bahlburg and his collaborators leveraged fishing vessels already in operation to gather vast quantities of acoustic data in their new paper published in the *Proceedings of the National Academy of Sciences. *Echosounders, or sonar systems, fixed to the bottom of vessels scan the environment by emitting sound waves that reflect billions of krill packed tightly together. By measuring how long the acoustic reflections take to return to the hull of the vessel, researchers can estimate populations of krill and their predators across an area.
The researchers discovered year-round conflict between vessels and key predators, as well as seasonal and regional challenges. Seven years ago, voluntary restrictions were established by the industry, in an effort to reduce competition with penguin breeding colonies. So far, though, this hasn’t prevented or resolved conflict; it’s merely shifted it geographically.
Here’s the catch: As the fleets have moved from the Antarctic Peninsula to the northern shelf of the South Orkney Islands where they begin fishing in summer, vessels compete with penguin breeding colonies during their main breeding season. In autumn, fisheries compete intensively with whales during a critical time when whales need to build fat reserves for migrations to their breeding grounds nearly halfway across the world.
The potential for scarcer swarms of krill, or areas where predators are unable to access sufficient prey, poses a significant challenge. But countries have been unable to agree on a distribution of catch. If even one nation objects to a ruling, it fails. In 2024, Russia and China voted to roll back Conservation Measure 51-07, a ruling established in 2009 by the Commission on the Conservation of Antarctic Marine Living Resources under the Antarctic Treaty System. This measure regulated krill fishing by dispersing it geographically, preventing companies from full-on extractions of the richest krill fields in a single area.
Now, a larger and longer commercial fishing window sits at the helm of an industry that is left to self-regulate and locate based on efficiency and profit. While current krill fisheries are harvesting 1% of their quota, predators need swarms of billions. The 1% of the krill fishery that is harvested is the most valuable in this region. “Think about the undue influence on the 1% of the richest Americans on everyone else; theoretically, it is that kind of effect,” says Savoca.
As far away as they may seem, Antarctic ecosystems are transforming as humans interfere with predator-prey interactions. While current fishing rates appear sustainable in isolation, the krill industry's increasingly efficient methods of fishing and their growing concentration during critical feeding periods and in key habitats create unknown risks. The question isn't just whether we're overfishing krill — it's whether we're disrupting the ecological foundation of the Southern Ocean in one of our planet’s most extraordinary environments.
Top image: The fishing vessel ‘Sejong’ navigates around icebergs near the Antarctic Peninsula coast in the Antarctic Sound. Credit: Dominik Bahlburg, Alfred Wegener Institute.
Amelia Macapia is a science writer and marine biologist at the Woods Hole Oceanographic Institution in Massachusetts. Her interests include ocean and climate issues, bioacoustics, and sensory ecology. She holds a B.Sc. in Biology from Tufts University and has contributed to publications including Tufts Daily, Oceanus Magazine, and MIT Science Policy Review. You can read more about her work on her website, LinkedIn, or email her at ameliamacapia@gmail.com.
Katherine Kornei is a science writer based in Portland, Oregon. She holds a B.S. in Astrophysics from Yale University and an M.S. and Ph.D. in Astronomy from the University of California, Los Angeles. Katherine’s work has appeared in Science, Eos, Scientific American, and the New York Times, among other outlets. www.katherinekornei.com.
The NASW Perlman Virtual Mentoring program is named for longtime science writer and past NASW President David Perlman. Dave, who died in 2020 at the age of 101 only three years after his retirement from the San Francisco Chronicle, was a mentor to countless members of the science writing community and always made time for kind and supportive words, especially for early career writers.
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