License to krill: Overfishing the ocean’s keystone species

Emerging Voices

License to krill: Overfishing the ocean’s keystone species

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Small shrimp make a big splash when it comes to the ocean’s health. Industrial fishing is threatening krill’s chance of survival — and our own.

Editor’s note: This is the latest in our Emerging Voices series featuring work from university students on topics related to climate and capital.

Krill are the most abundant animal on the planet. They feed the world’s largest creatures, whales, and when they swarm together they give the Southern Ocean a red tint that’s visible from space. But these days, consumers are more likely to recognize krill from the labels on supplement bottles. With the rise of health fads, scientists warn krill-based industries are driving marine animals to starvation. Side effects may include dramatically upsetting the Earth’s climate.

The Southern Ocean surrounding Antarctica is home to the largest krill fishery in the world. Since the 1970s, industrial-scale fishing operations and disappearing sea ice have depleted Antarctic krill populations by 80%. To make matters worse, krill decline plays a significant role in driving global climate change.

Krill poop sinks, contributing to carbon drawdown

With over 700 trillion individuals in the Southern Ocean alone, krill form a vital carbon sink. As they graze on carbon-rich phytoplankton, krill excrete their waste deep in the water column. That’s right…krill poop sinks. And as it does, C02 is removed from the atmosphere where it contributes to global warming and settles deep in the ocean where it’s stored for generations.

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Much like forests, thriving krill can help store a lot of carbon. That makes disturbing the planet’s krill stock an incredible risk. Scientists expect the loss of krill to upset the ocean’s chemical cycling, as krill do the important work of transporting essential nutrients on their daily migrations through the water column. The loss of krill is not just a problem for the South Pole, however. Krill depletion would affect the whole planet’s ocean and climate systems.

Scientists expect the loss of krill to upset the ocean’s chemical cycling, as krill do the important work of transporting essential nutrients on their daily migrations through the water column.

But as krill fisheries ramp up their yearly harvest, it seems these are gambles the industry is willing to take…for all of us.

Small but mighty

Antarctic krill each weigh in at a single gram. But together, these shrimp-like crustaceans swarm into dense clouds tens of kilometers wide and a hundred meters deep. Krill occupy an essential place in the food chain, making up a large percentage of the ocean’s biomass to the tune of 379,000,000 tonnes. To put that in perspective, the collective weight of all blue whales, the largest species in the animal kingdom, weighs in at less than 500,000 tons. Many beloved species, from blue whales to leopard seals to Adélie penguins, all depend on krill.

Krill play the role of “keystone species” in the Antarctic ecosystem. Without them, countless animals that depend on them directly for survival would die while shifting food webs out of balance. These effects can ripple out to other ecosystems whose food webs are intertwined across vast ocean scales.

The word krill is Norwegian for “whale food.” And for good reason. They sustain the largest animal known to have ever lived on earth, the blue whale. High in protein, vitamin A and omega-3 fatty acids, it’s easy to see why krill is a great food source. Now, humans are increasingly keen on this diet. The total harvest of krill, about 150–200,000 tonnes a year in 2021 and much more today, was historically used as food for aquaculture, livestock and pet food. But recent pressure to harvest krill comes from a high demand for an unsuspecting product – krill oil.

Krill oil is now big business

The global market for Antarctic krill oil is booming. It’s been successfully marketed to buyers around the world as the “best” and “cleanest” alternative to fish oil. That’s made krill oil big business. In 2022, $633 million worth of krill oil was traded on the global market. Demand is driven by older, wealthy populations in Europe and Japan who buy krill oil to treat everything from heart disease to high blood pressure. Companies have eagerly jumped to supply these consumers. Their reach is growing.

In 2022, $633 million worth of krill oil was traded on the global market. 

According to an investigation by Oceans Inc., in 2020, vessels fishing in just one subarea of the Southern Ocean caught 446,783 tonnes of krill, the largest single-year harvest on record. According to a report by the Changing Market Foundation, more than half of these krill were harvested by the Norwegian fishing and biotech company Aker BioMarine, a company accused of trapping and killing humpback whales in their massive krill-fishing nets. Other big players are gaining power.

Rushing for gold

Krill fishing isn’t an easy business. For fishing companies that can afford to fish for krill, it’s a treacherous journey to reach the South Pole. Like an international gold rush, wealthy ships compete at the start of the season to catch as much krill as possible before the set international limit is met. The annual krill cap is approached earlier every year, which impacts the feeding season of predators. Pressure is now mounting as investors from nations like China and Russia pour money into more and more efficient vessels capable of processing tonnes more krill to be sold on the global market.

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The body that regulates krill fishing in the Southern Ocean, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has set “precautionary limits” on krill harvests. These limits are designed to protect predators, like penguins, that rely directly on krill. Problematically, this number is based on historically unreliable population surveys, and it aims to preserve just enough krill to maintain a sustainable population.

Clearly, that’s not enough. Predators of krill are starving to death. Studies have found that the food stress experienced by penguins is caused by intense overfishing in krill-abundant areas close to land, overlapping with their breeding grounds. Site location is a factor that such policies cannot account for. Many penguin populations are in sharp decline, and acute overfishing in their habitats is to blame.

The loss of sea ice due to climate change has jeopardized krill spawning grounds, while ocean acidification and plastic pollution are adding new threats.

Climate change triple threat

Krill aren’t just threatened by people. They are under attack from all sides. The loss of sea ice due to climate change has jeopardized krill spawning grounds, while ocean acidification and plastic pollution are adding new threats. These impacts may create a feedback loop, as problems reinforce themselves and become more severe. For example, fewer krill means less carbon drawdown, thereby accelerating ocean acidification and ice melt. The krill fishing industry, however, shows no signs of letting up. A recent market report predicts that the global krill market will reach $1 billion by 2030. 

In 2018, international groups advocated for a marine reserve that would protect 1.8m square kilometers around the Weddell Sea. Such measures would greatly reduce the stress on local marine animals, while a ban on krill fishing would eliminate human competition with Antarctic species. But in 2020, those efforts were rejected by countries like Russia, one of the voting CCAMLR member countries. More public support for a marine protected area would go a long way to push governing agencies, environmental groups, and nations to take a stand for krill.

It’s clear that krill are worth far more in the ocean than in a pill bottle. The benefits of omega-3 oil are dwarfed by the overwhelming costs to the planet if regulatory agencies get it wrong. If the problem of krill decline is not addressed, the world runs the risk of losing its most abundant species — along with the whales and penguins that depend on them. 

Krill’s future is precarious, and, therefore, so is ours. It’s time to stand up for the little guy.

Written by

Anna Hedinger

Anna Hedinger is a student at Wellesley College majoring in Environmental Studies. As a conservationist, they have worked in land and ocean stewardship in rural Montana and Alaska, and grew up maintaining trails in the Bob Marshall Wilderness. Anna is passionate about environmental journalism.