On World Penguin Day, an Expert Shares New Warnings

Lucas Krüger, a seabird ecologist with the Instituto Antártico Chileno who attends the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) meetings as a scientific adviser to the Chilean delegation, is the lead and co-author of new studies in Diversity and the Nature publication Scientific Reports that look at recent declines in the populations of chinstrap penguins. Chinstrap penguins are one of three species of Pygoscelis penguins (Latin for brush-tailed) that call the Antarctic Peninsula region home. The region’s other two Pygoscelis penguin species are the Adélies and gentoos.

This interview has been edited for clarity and length.

We interviewed you about penguin research back in 2020. How does your new research relate to that previous study?

Courtesy of Lucas Krüger

Various studies published over the last 10 years have proposed that a reduction in krill density is the main factor for the steep reductions of penguin breeding colonies in the northern part of the Antarctic Peninsula. One article showed that the number of young penguins living to reproductive maturity declined in concert with fewer krill. Since krill abundance varies substantially from one year to another, years of very low krill numbers are expected to affect penguin populations. In 2020, we also published a paper in Ambio that an increase in the frequency of years with low krill abundance could cumulatively lead to a decrease in Pygoscelis penguin populations. Our new article in Scientific Reports shows that after one year of winter with low sea ice cover, krill were less abundant at deeper depths the following summer. Consequently, penguin breeding success was significantly lower that particular summer compared to a previous year when krill were more abundant. This could explain the long-term reductions in the survival of young penguins to adulthood—if we can confirm that this happens consistently over a broader geographical area.

Why is it important to study chinstrap penguins?

The three Pygoscelis penguin species inhabiting the Antarctic Peninsula have adapted to feed on krill, at least in the Antarctic Peninsula where krill is the most abundant prey, but each species is a little different. Gentoos are more flexible in their diet and can compensate for periods of low krill by feeding on other prey. Adélie penguins in the northern part of the peninsula are in decline, yet seem to thrive in other parts of their range, including further south and in East Antarctica. However, more than 60% of the global chinstrap penguin population lives in the Antarctic Peninsula, which is experiencing fast changes. Most chinstrap breeding colonies in the peninsula region have declined over 50% in the last 40 to 50 years. When I calculated their population variability taking their life span into account, I found that the chinstrap population in the Antarctic Peninsula matches the category of vulnerable to extinction, as they have decreased around 30% in three generations.

The population is declining so much that it’s actually vulnerable to extinction? What do you believe is the cause of that? 

I have no doubt that one important contributing factor to the chinstrap penguin population’s decline is the fast warming affecting their prey [krill]. Other contributing factors might include an increase in extreme climatic events, i.e., heavy rains and heat waves affecting the survival of chicks and adults, and possibly other factors we haven’t accounted for. What concerns me the most is that this is happening to a large proportion of the global chinstrap population.

Your research, and that of others, covers long-term cycles in the Antarctic Peninsula. Why is that important?

Such research allows us to understand the fast changes taking place in the Antarctic Peninsula and how biodiversity is responding. A better understanding can help us develop and implement measures to counteract those changes, or at least avoid adding additional stresses.

So back to chinstrap penguins in particular. For several years, you’ve been a scientific adviser to Chile’s delegation to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the international organization responsible for conserving biodiversity in the Southern Ocean surrounding Antarctica. Does CCAMLR have any tools to protect chinstrap penguins?

CCAMLR was originally created in 1982 to reduce the ecosystem impacts of fisheries in Antarctica—particularly the Antarctic krill fishery, which, at the time, was growing rapidly. I think the organization’s main tool to support chinstrap penguins is the regulation of the krill fishery; a sustainable and controlled krill catch by fishing countries is better than an unrestricted fishery. However, with the fast changes in the region where the krill fishery is concentrated, and the uncertainty about how krill are responding to these changes, the efficiency of existing regulations has been questioned.

So, if there is uncertainty in how krill are responding to these changes, what can be done to help protect the penguins?

While we can’t address all uncertainties through krill fishery management alone, CCAMLR can protect key areas for krill and their predators as a precautionary measure to avoid unexpected outcomes of any new management strategy it adopts.

In particular?

CCAMLR is currently reviewing its management strategies regarding the krill fishery, and many scientists involved in this process think that a marine protected area needs to be implemented for the Antarctic Peninsula region.

How does your new research influence the marine protected area proposed for the Antarctic Peninsula region?

Because chinstrap penguins are sensitive to the fast changes affecting krill—and because we’re able to make direct links between krill availability and penguin behavior and population responses—we need to protect key areas for penguins and krill, especially since we cannot address the uncertain outcomes of krill fishery management. We need to avoid the fishery becoming an additional pressure to the Antarctic marine ecosystem. Our research adds one more piece to the puzzle in understanding how climate change is affecting not only penguins, but the ecosystem as a whole. It is urgent that we generate spaces without extra pressures to help species boost their resilience to climate change.

For World Penguin Day, is there one final thing you would like to share about these birds?

Most people see penguins as cute animals. But, in reality, penguins are tough animals that have evolved to exist and inhabit some of the harshest environments on the planet. However, even penguin toughness has limits, and evolution didn’t prepare them for modern pressures. Half of the recognized penguin species globally are at some level of risk of extinction as a result of our impacts on the Southern Ocean and the global ocean as a whole. I have no doubt that, without further action, in the near future we’re going to see more species becoming at risk of extinction. World Penguin Day should not be just a celebration of penguins, but rather a day for being conscious about their plight—and taking action.