Sometimes, it can seem like the natural world is just being bombarded with one piece of bad news after another. So we’re pleased to announce that, for once, something good has happened – really good!

For the first time in nearly half a century, large groups of southern fin whales have been seen feeding together in the Antarctic. “I’d never seen so many whales in one place before,” said Bettina Meyer, a biologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and at the University of Oldenburg as well as the Helmholtz Institute for Functional Marine Biodiversity, in a statement. 

She’s co-author of a new study, published in the journal Scientific Reports, in which the sight was documented. Meyer, who led the expedition, said she "was absolutely fascinated watching these massive groups feed.” 

Originally sent out to investigate the effects of climate change on krill, one team performed survey flights covering 3,251 kilometers of the Antarctic Peninsula. They found 100 groups of fin whales, each consisting of one to four whales – and in the Weddell Sea, near Elephant Island, they spotted groups of around 50 and 70 individuals in one area.

“I ran straight to our monitor, which uses acoustic measuring methods to show the presence and size of krill swarms in the water,” Meyer explained. “And based on the data, we were able to identify the swarms and even see how the whales hunted them.”

Fin whales are second only to blue whales in size, and can live as long as 90 years. They’re fast swimmers, which for a while gave them an edge over their cetacean brethren when it came to escaping commercial whalers – but with the dawn of modern whaling tools like steamships and explosive harpoons, the species was hunted to near-extinction.

So, news of rebounding fin whale populations is extremely welcome. Not just for the whales themselves: their return to their ancestral feeding grounds has consequences at every step of the ecological ladder.

“When the whale population grows, the animals recycle more nutrients, increasing the productivity of the Southern Ocean,” Meyer explained. “This boosts the growth of algae, which for their part absorb carbon dioxide from the atmosphere through photosynthesis, reducing the atmospheric CO₂ concentration.”

Like so much in life, it all comes down to poop: more whales equals more poop, and whale poop is really good for the ocean. It contains nutrients like iron, which is hard to get in the Antarctic, so it promotes the growth of phytoplankton in the ocean.

Phytoplankton, or microalgae, is food for krill – the tiny bioluminescent crustacean that essentially acts as the foundation of the Antarctic food chain. Poor old krill get eaten by whales, seals, penguins, fish, you name it, – so more krill is good for a whole ecosystem of species.

Best of all, it looks like this isn’t a one-off. A year after the original expeditions, the same research team revisited the whale feeding grounds. This time, they didn’t see 50 or 70 of the beasts – they saw as many as 150.

“Even if we still don’t know the total number of fin whales in the Antarctic, due to the lack of simultaneous observations, this could be a good sign that, nearly 50 years after the ban on commercial whaling, the fin whale population in the Antarctic is rebounding,” says Bettina Meyer.