A New Explanation for Decreasing Penguin Populations

The Lenfest Ocean Program’s Research series has recently released a study which reexamines changes in Penguin populations. While previous studies showed how changes in ice melt have influenced shifts in penguin populations, this study looks at how penguin populations may also be influenced by the availability of their primary prey – krill. The combination of climate change, increased human fishing and rival krill predators significantly influence krill’s availability. Some studies show that on account of this combination of factors the southern ocean’s krill populations have decreased by nearly 80% since the turn of the 20th century. Krill being the penguins’ primary food source, it is necessary to study the link between the two species, in order to better predict the future of Antarctic penguin populations.

The study uses over thirty years of data, focusing on populations of both Adelie and Chinstrap penguin species. The two penguin species have declined by more than 50% in the South Shetland Islands region, over the course of the study. The study suggests that penguin populations more closely track patterns in krill abundance over time. Penguin populations are likely to continue their decline, so long as climate change and krill populations continue their course of change.

This is most alarming for Chinstrap penguins, which breed almost exclusively around the South Shetland Islands. Because they have such a limited range, the combination of diminishing ice due to climate change, and decreasing krill populations in the South Shetlands is especially concerning to Chinstraps, compared to other penguin species which aggregate in multiple regions.

Though humans are not the only factor that is removing krill from the Southern Ocean ecosystems, how we capture krill is one factor over which people do have some control. This speaks to the importance of creating more Marine Protected Areas (MPA) around the Antarctic. While it was a victory to declare the the Ross Sea an MPA, it is necessary that there be more. With more MPAs especially in areas of great krill aggregation, there would also be greater penguin protection.