Research has revealed that blue whales have become increasingly silent in recent years – here's what it means for humanity.
For anyone unfamiliar with the ocean, blue whales are the largest species of whale and, measuring on average between 20 and 24 metres, are the biggest animals to ever live on the planet.
However their future is uncertain.
Blue whales have been knocking about on Earth for millions of years and were nearly hunted to extinction during the 1900s, until whaling was banned on blue whales in 1966.
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Since then, blue whale populations have increased; however, there is a new threat to their existence – the planet's changing climate.
The worrying trends were noted after a study conducted by researchers at the Monterey Bay Aquarium Research Institute found that blue whale songs had dropped by almost 40 per cent over the past six years.
Like most breeds of whale, male blue whales utilise song in order to attract a mate during breeding season, with a decrease in song suggesting a worrying trend for the future of the species.
So what's caused this change?
According to John Ryan, a biological oceanographer at the Monterey Bay Aquarium Research Institute, a deciding factor was likely a 2013 marine heatwave known as The Blob.
The Blob is said to have raised ocean temperatures by more than 4.5°F, which caused huge damage to marine populations.
The rise in ocean temperatures led to harmful changes in ocean chemistry, allowing toxic algae to bloom.
"It caused the most widespread poisoning of marine mammals ever documented. These were hard times for whales," he explained in an interview with National Geographic.
The heating up of the ocean also caused the population of krill, which makes up the overwhelming majority of the blue whale's diet, to collapse, meaning that most creatures were struggling to find food.
"When you really break it down, it’s like trying to sing while you're starving. They were spending all their time just trying to find food," he added.
"We don’t hear them singing. They’re spending all their energy searching. There’s just not enough time left over - and that tells us those years are incredibly stressful."
And with 2025's summer months seeing the warmest temperatures on record in the Pacific Ocean, according to the BBC, it looks like a trend which will continue.
Co-author and marine biologist Kelly Benoit-Bird added: "When we have these really hot years and marine heatwaves, it’s more than just temperature.
"The whole system changes, and we don’t get the krill. So the animals that rely only on krill are kind of out of luck.
"There are whole ecosystem consequences of these marine heat waves.
"If they can't find food, and they can traverse the entire West Coast of North America, that is a really large-scale consequence."
Topics: Environment, Animals
Brenna Cooper