Tracing the Adelie penguins’ food – are the Adelies in decline?

Imagine that you went out to buy shrimp but the closest grocery store didn’t have it in stock. Even then, the same store most likely has their selection of other seafood and meat for you to choose from, so that won’t be too devastating.

Adelie penguins can do the same: when they can’t get enough krill – a tiny shrimp-like crustacean that is their main source of food – they can switch to eating fish such as the Antarctic silverfish.

Link to flickr photo of Adelie penguin
Adelie penguin by Marie and Alistair Knock. Photo from flickr.

Such a switch can be triggered by a competitor for the Adelies’ food: baleen whales. When these whales arrived to the Antarctic in the spring to feed, they ate about 2000 times more krill than penguins would. Researchers found that during such times, the Adelie penguins switched to eating much more fish than they ate krill. Once the whales migrated back to their wintering grounds, the Adelies returned to a primarily krill diet.

Today, a lot is at stake for the Adelie penguins. Krill fisheries are gradually depleting the krill stock, and the rising Antarctic sea temperatures makes it harder for krill to survive: young krill feed on ice-algae living on the surface of floating ice sheets, but global warming melts the ice and removes the krill’s food. Also, the revival of whale and seal populations in this post-whaling period adds competition for the shrinking food source for the Adelies.

Krill are not endangered – they are still abundant according to the World Conservation Union (IUCN) criteria. However, the number of krill has reduced by a striking 80% over the last 30 years.

Link to for photo of Adelie penguins on ice
Adelie penguins by Nick Russill.

Can the Adelie penguins give up on krill and eat fish? The data suggests not – 2011 news reported that Adelie penguin populations are declining along with the krill populations. There are a lot of other possible factors that could be making it harder for the Adelies to survive – but an animal’s food is essential to its living. To protect a species, we must know what food must be secured for them, and we must understand the interconnected web of organisms that can affect its food source.

What do your favorite animals eat?

Further reading:

The impact of climate change on the Adelie penguins is more complex – in some regions, Adelie penguins benefit from broken up ice to be able to access open water to capture food, but in other regions, Adelie penguins suffer from losing ground to lay eggs and raise their young.

The idea for this article was inspired by a related article on At This Time News Magazine, “Adelie penguins: cool, efficient killing machines” that describes a study adding further understanding to how Adelie penguins capture their prey) (This article was published in April 2013 on At this time the news magazine and Community of Accounting and Business Professionals blog)

October 21, 2013Permalink Leave a comment

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