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The secret life of Antarctic krill / Rodolfo Werner

Rodolfo Werner

Krill, a small shrimp-like crustacean, underpins the food web of the entire Antarctic marine ecosystem. Yet climate change and the concentration of krill fishing in just a few areas are a threat to their existence, and therefore to the existence of all species in Antarctica.

Image © Pete Lindzinskey

Rodolfo Werner

Image © Pete Lindzinskey

Toward the ice

The majesty of the mountain peaks and their hanging glaciers; the blue shine and vastness of the sea ice; the long sunsets and endless skies; the delicate beauty of floating icebergs; the rich variety of marine life. Despite being the most frigid place on Earth, and perhaps because of it, Antarctica can have a very special effect on your soul—at least I know it did for me.

I grew up in Buenos Aires, Argentina, on the banks of the La Plata River, a river wide enough to momentarily deceive you into thinking it’s the ocean. I spent long afternoons contemplating and venturing into the river and, as Maria Elena Walsh (a renowned Argentinian poet) used to say, “dreaming of the sea from the river.” As a young man, I always had an eagerness to sail, to travel on the sea, to explore, and to reach unknown places. Without a doubt, this influenced me to study marine biology, hoping to spend my life studying what I love: the sea.

Being Argentinean, the sea always meant to me the seas of the “South,” that is, the Patagonian Sea and the Southern Ocean surrounding ​​Antarctica.

I didn’t know I would actually get to visit Antarctica one day, but since I was a kid the ice continent attracted me in a way that transcends the intellectual, and I found myself always dreaming about venturing into Antarctica and becoming a polar explorer.

Yet nothing could prepare me for what I would feel when I actually visited the southernmost continent of our planet.

From the very first time I set foot in Antarctica, it caused an internal change in me that I didn’t really expect. In the vast icy landmass of Antarctica, time takes on an unusual dimension. In the austral summer, days last for, well, months—providing us with a unique opportunity to reflect on how humanity relates to nature and the responsibility we have to protect the ecosystems that keep us alive. The cliché that everything in the universe is connected and interrelated is distinctly manifest in Antarctica everywhere you look. In fact, all life in Antarctica—from microscopic bacteria to 90 foot-long Antarctic blue whales—is truly connected and dependent on the ocean and on what happens to the ocean. 

An iceberg with a blue shine in Cierva Cove, Antarctica · Rodolfo Werner

I have been fortunate enough to spend almost two decades visiting Antarctica and studying the life of the icy continent. Over the past 17 years, I have become increasingly fascinated by a small shrimp-like crustacean that underpins the life of Antarctica. This little crustacean is called “krill,” and it is perhaps the best example of the inextricable connections of Antarctica.

Mighty krill

“Krill” is a common name to describe about 80 different species of small crustaceans, present in all the world’s oceans, that resemble shrimp but are not actually shrimp. Seven krill species live in the waters around Antarctica, the most abundant of which is known as Euphausia superba, or Antarctic krill. The species name superba, meaning “superb,” points to one of its main characteristics: it is the largest of the krill species, reaching an average length of about six centimeters (about the size of your ring finger). 

Krill form some of the largest aggregations of animal life, swimming in massive groups called swarms. A close-up of an individual krill shows that they seem to swim with a clear purpose, both acutely aware of and sensitive to the surroundings, moving forward, with big black eyes like lanterns, their limbs moving in swift and perfect synchrony. If their feelers touch anything not to their liking, they can immediately change direction, even capable of moving backward quickly. These marvelous creatures can also grow rapidly when food is bountiful and shrink when it is in short supply. To “shrink,” krill shed their carapace (the external skeleton) through a process called molting. They’re also relatively long-lived animals, able to reach a lifespan of up to 11 years. 

Antarctic krill is one of the most abundant species in the world, with a biomass estimated to exceed that of all the people on the planet.

And it needs to be so, given that Antarctic krill underpins the food web of the Antarctic marine ecosystem, acting as the primary source of nutrition and sustenance for species like whales, seals, and penguins. In fact, nearly every species in Antarctica—whether on land, in the water, or in the air—either feeds on krill directly or feeds on species that feed on krill. In other words, the importance of krill cannot be overstated.

“Antarctic krill underpins the food web of the Antarctic marine ecosystem” · Rodolfo Werner

The krill fishery

Unfortunately, the nutritional characteristics that make krill essential to the health of the Antarctic ecosystem also make them a highly prized commodity. Over the last 15 years, the Antarctic krill fishery (i.e. the fishing of krill for commercial purposes) has grown considerably, boosted by technological advances and the emergence of new lucrative markets. Since 2005, the amount of krill catches has risen from around 100,000 tons of krill fished per year to more than 400,000 tons fished during the 2019 to 2020 fishing season. Common applications for krill, which is rich in omega-3 fatty acids, include its use as a nutritional supplement for people and as feed supplements for aquaculture.

Krill is immensely abundant, yet there are very real concerns that Antarctic krill could be overfished in some areas and cause uncertain ecological consequences. One challenge is that krill fishery operations are very localized, that is, concentrated in just a few areas. As a result, the same areas are fished over and over, gradually diminishing the amount of krill and altering the location of the best foraging grounds for other species. This could have serious impacts on predator species, such as penguins, which are highly restricted as to how far into the sea they can go to hunt for food, especially during the breeding season. 

The krill fishery can also impact the reproduction rates of Antarctic species. The availability of krill during the breeding season is essential for the reproductive success of many species that prey on krill. And it’s easy to see why: if you fish very heavily in an area that is being used by particular penguin colonies, for example, you will impact the local amount of krill, and the breeding success of that penguin colony will suffer.

The Antarctic krill fishery is gradually altering the location of the best foraging grounds for other species like penguins · Rodolfo Werner

Virtually all the krill catch is concentrated in an area well-documented as breeding grounds of species that feed on krill. Yet it is very difficult to quantify the feeding needs of krill predators in areas of overlap with the fishery, since the availability of krill becomes challenging to determine. This creates management problems, and how much krill is left in the water is difficult to confirm.

And this is already having important effects.

The current situation of many Adélie and chinstrap penguin colonies in the South Shetland Islands and the Antarctic Peninsula is worrying. Their numbers have decreased by 50 percent in the last 30 years.

And while the exact reasons for the decline in numbers are open to debate, krill fishing has undoubtedly contributed.

Climate change

Adequate management of krill fisheries is critical, but it is also incredibly challenging to implement. And worsening climate change is not making matters any easier. The effects of climate change are already proving to be catastrophic in the Antarctic Peninsula, a finger of land that extends from the Antarctic continent toward the southernmost tip of South America. The Antarctic Peninsula is known as a hotspot for Antarctic krill, and for tourism: 99 percent of visitors to Antarctica visit the Peninsula. Yet it is also one of the areas that has been most affected by rising temperatures due to climate change.

The western Antarctic Peninsula is the fastest warming area in the Southern Ocean and one of the fastest warming areas in the world. As a result, we are seeing a reduction in sea ice, an increase in precipitation in the form of rain, the acidification of the sea, and many other impacts that represent a “sea of uncertainty” for the future of Antarctica. In fact, the massive reduction in sea ice that forms during the winter is producing a decrease in the availability of sea-ice algae, the main food source for krill. Certainly, if the main food source for the Antarctic ecosystem is starving, that sets the stage for a potentially irreversible domino-effect collapse.

Climate change is also extending the fishing period in Antarctica. Historically, the Antarctic krill fishery only operated during the austral summer. However, since the sea ice began to retreat, the season is extending. And to make matters worse, as this sea ice disappears, fishing vessels are increasingly able to fish some parts that were previously too difficult to reach.

A pod of orcas swims toward a crabeater seal on floating ice. Antarctica is experiencing a massive reduction in sea ice due to a warming climate. · Rodolfo Werner

The tip of the solution iceberg

Recognizing the critical role that krill occupies in the Antarctic ecosystem—and in response to increasing commercial interest in Antarctic krill resources, plus a history of over-exploitation of several other marine resources in the Southern Ocean—the Commission for the Conservation of Antarctic Marine Living Resources, or CCAMLR, was established in 1982.

Also known as the “Krill Convention,” CCAMLR seeks to conserve Antarctic marine life through research, monitoring, and the application of conservation measures.

CCAMLR is not perfect, but this international commission, made up of 26 member countries including the European Union, represents an excellent example of international cooperation and of countries coming together to put the protection of an area first, before economic and political interests.

CCAMLR was conceived as a model convention in that it is governed by two novel basic principles: ecosystem-based management and the precautionary approach. The first one contemplates not only the impact of the fishery on the target species of the fishing activity (that is, the species to be extracted, in this case krill) but also on the dependent species. Given krill’s place in the Antarctic marine ecosystem, this principle is central to CCAMLR. On the other hand, the precautionary approach aims to minimize the impact on the ecosystem that cannot be reversed in a period of 20 to 30 years.

Rodolfo Werner on expedition in Antarctica, in the Gerlache Strait separating the Palmer Archipelago from the Antarctic Peninsula · Rodolfo Werner

Until 2007, the Antarctic krill fishery was poorly regulated, but significant progress has been made since. Krill catch limits now exist in the Antarctic Peninsula. And while these limits still do not take into account the smaller-scale interactions between the fishery, krill, and krill predators, they do represent a step in the right direction until CCAMLR is able to agree on better fisheries management.

What’s next

CCAMLR is currently working toward better management of the krill fisheries. In addition to this, the impact of the fishery could be reduced by moving part of the fishing operations to pelagic areas, that is, areas far from the coast, at least during the breeding season of krill-dependent species. It would also be important to encourage krill fishing vessels to conduct surveys to help with up-to-date estimates of krill biomass, as the long-term availability of krill is in their best interest. In addition, the krill fishing industry should contribute to strengthen and fund programs to monitor the Antarctic marine ecosystem.

Another important tool to protect Antarctic marine life and ecosystems is the establishment of marine protected areas, or MPAs, which are similar to national parks but on the water, and can offer some of the most effective protection to marine resources if implemented adequately. CCAMLR designated its first MPAs in the South Orkney Islands in 2009 and in the Ross Sea in 2016, the latter becoming the largest MPA on the planet, covering more than 1.5 million square kilometers. This was a major achievement for CCAMLR, but there is still a lot of work to be done and MPAs remain one of the most hotly contested issues in CCAMLR meetings, which take place in Hobart, Tasmania in October every year.

Currently, there are proposals for three new MPAs, one in East Antarctica, one in the Weddell Sea, and one in the Antarctic Peninsula. Together, the establishment of these MPAs could become the greatest sanctuary for marine life in the world. But it won’t be easy. In particular, the establishment of an MPA in the Antarctic Peninsula represents a huge challenge for CCAMLR because it requires finding a compromise between the protection of marine biodiversity and krill fishing operations. And the cooperation that makes CCAMLR such a success is a double-edged sword: any action coming from CCAMLR must be supported by consensus from the 26 CCAMLR members. Trying to protect a place with no human population is not easy, but CCAMLR is an example of what can be accomplished when nations decide to work together for the benefit of everyone, even if it takes perseverance and endless amounts of patience.

“Despite being the most frigid place on Earth, and perhaps because of it, Antarctica can have a very special effect on your soul—at least I know it did for me” · Rodolfo Werner
After so many years working on Antarctic issues, I am convinced that economic arguments are becoming increasingly less important when it comes to the conservation of Antarctica. This is because Antarctica should not be measured by its economic value, but by the value of its beauty and its role in maintaining balance for our planet.

It is awe for nature which I believe is necessary in today’s environmental debates, especially at international policy arenas such as CCAMLR. If we recognize the beauty of Antarctica, we can speak up for krill and all the other Antarctic creatures whose fate depends on the choices of CCAMLR members.

Time is not on our side. But while not everyone is fortunate enough to visit the Ice Continent in their lifetimes, we must remember that to protect Antarctica is to protect the planet. Just like krill is small but mighty, so are we relative to the challenges ahead. But by coming together, we can secure the protection of Antarctica, of its wildlife, and ultimately, of ourselves.


Rodolfo Werner

Wildlife conservationist

Rodolfo is a wildlife conservationist from Argentina who has devoted many years of his career to the study and conservation of Patagonian wildlife, marine mammals, the Southern Ocean and Antarctica. He has consulted for many international conservation organizations on issues such as marine protected areas, Antarctic krill, fisheries, policy, and marine mammals. Dr. Werner is currently an advisor to ASOC and the Pew Charitable Trusts.

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