Blue Whales Are Going Silent
Inside the acoustic warning signs of a changing ocean
When I published We Nearly Killed the Blue Whales Once, I focused on the invisible changes in deep Antarctic water that are starving the food web from below.
Since then, I’ve been looking at how those changes are showing up elsewhere, namely across the Pacific. It turns out we’ve had a warning system for years, but we just weren’t listening.
In this piece, I’m following the sound, or rather, the sudden absence of it. Blue whales are still migrating. Still diving. Still surviving. However, they aren’t singing.
That silence is the real headline.
You will not hear it on the news. Most people will not hear it at all.
Yet across one of the loudest landscapes in nature, the world’s biggest mammals have stopped making noise.
Blue whales, the 150-tonne giants that once reverberated through every ocean basin, are falling quiet. They are not silent due to nets or ship strikes. They are simply running out of food.
A blue whale that has no energy to sing is not just tired. It is in trouble. So is the ecosystem around it.
Songs From a Vanishing Ocean
These following recordings, collected by the Australian Antarctic Programme, capture the haunting calls of blue whales in the Southern Ocean. Each example reveals a different aspect of how whales communicate.
Antarctic blue whale D-calls
Recorded in the Ross Sea and sped up 4× to be audible. These social feeding-ground calls vary across individuals, seasons, and years.
Antarctic blue whale Z-calls
Sped-up 8× recording from a 2014 Antarctic mooring near Casey Station. These long-range calls are likely made by individuals for distant communication.
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The Sound of Collapse
In 2014, a mass of warm water settled in the northeast Pacific and refused to leave. Scientists called it “The Blob”. It destabilised ecosystems, scrambled weather and wrecked fisheries.
Researchers from MBARI and NOAA had just started a six-year acoustic monitoring project off the California coast. Their hydrophones recorded every underwater vibration: earthquakes, ships, shrimp snaps, and the low-frequency calls of whales.
During the peak of the marine heatwave, blue whale calls dropped by nearly 40%. Fin whale song also declined. Humpbacks did not go quiet; they have a more varied diet and adapted more easily.
Blue whales feed almost entirely on krill. During the heatwave, krill collapsed. Without tightly packed swarms, whales could not feed efficiently. Every dive became a gamble and when feeding fails, singing stops.
John Ryan, one of the lead authors, said it plainly: “It’s like trying to sing while you’re starving.”
A Mirror on the Other Side of the Ocean
Researchers in New Zealand were studying blue whales for an unrelated project. They were not looking for signs of ecosystem breakdown. Even so, the pattern was hard to miss.
During heatwave years, whales in South Taranaki Bight produced fewer foraging calls. Song intensity fell the following season. The link between low food availability and reduced reproduction was unmistakable.
Dawn Barlow, who led the New Zealand study, described blue whales as ‘sentinels’. Their movements and vocal patterns reflect the overall health of the ocean. A quiet whale population tells you more than a population count ever could.
More Than a Whale Problem
Krill support entire food webs. Seals, penguins, fish and seabirds all depend on them. These small creatures also play a critical role in oceanic carbon cycling. When krill are eaten or die naturally, their carbon is transferred to the deep sea.
Fewer krill means slower carbon transfer. This weakens one of the ocean’s most important climate functions.
There is no separating whale silence from climate instability. They are part of the same unraveling pattern.
When the Ocean Loses Its Rhythm
The Blob did more than warm the water. It altered nutrient flows and disrupted upwelling. Krill and anchovy numbers fell sharply. Algal blooms spread, poisoning sea lions and other marine life.
During this time, researchers recorded not only fewer whale calls but also more stress indicators across multiple species.
Marine heatwaves like The Blob are no longer rare. According to a study in PNAS, their duration has tripled since the 1940s. They now cover entire basins and spike temperatures by up to 5 degrees Celsius.
These events are reshaping the ocean’s ability to recover. Temporary disruptions are becoming long-term shifts.
How Sound Becomes a Warning System
The value of the research lies not only in what it discovered but in how it was collected. Scientists used a single hydrophone on the seafloor, connected by a cable stretching 32 miles to the coast. No boats. No drones. Just years of continuous listening.
That listening revealed a pattern of behavioural collapse. Whales did not vanish, but their calls faded.
This is not sentiment. It is data. Whale song reflects prey availability, ecosystem stability, and reproductive effort. It helps researchers understand where change is happening fastest.
Even other species, like snapping shrimp, have started altering their sound profiles. In warmer water, they snap more frequently and more forcefully. Some scientists think this could indicate stress. The entire underwater soundscape is shifting.
Whales Run on a Different Clock
Blue whales can live more than 80 years. Since industrial whaling ended, only a few dozen generations have passed. Populations have rebounded somewhat, but they remain fragile.
No one knows exactly how repeated marine heatwaves will shape their future. Scientists suspect we may not see the full effects for another century.
We are dealing with species that operate on timescales longer than most human institutions. Listening gives us a way to track their future before we lose our grip on the present.
What You Can Do
If whale silence is a warning, then action is the response. Here’s where to start:
Support ocean sound monitoring
Right now, projects like Listening to the Deep Ocean Environment (LIDO) and Ocean Networks Canada are using hydrophones to listen for stress signals in real time. These tools can predict crises before they become catastrophes.
You can also follow the work of the Monterey Bay Aquarium Research Institute (MBARI), where much of the data in this story was born.
Reduce ocean noise pollution
Shipping noise is constant, global, and devastating — and it's rarely in the headlines. You can back groups like Quiet Oceans and OceanCare, who are lobbying for better shipping routes, speed limits, and technology.
Push for ocean-first climate policy
Your leaders are making climate decisions. Are they listening to the ocean? Find out. Ask them how marine heatwaves, krill, or blue carbon fit into their plans.
Write or call your local representative in the UK or the US.
Look for candidates or policies that mention:
- Blue carbon
- Marine heatwaves
- Deep-sea protection
- Krill and trophic web resilience
Back frontline ocean conservation
Support organisations doing real-time work on whale conservation, food web protection, and habitat resilience.
– Whale and Dolphin Conservation (where I work)
– Blue Marine Foundation
– Sea Change Project
– Indigenous Leadership Initiative (Canada)
– Oceana
Final Thought
The ocean is not just warming, its sound is changing.
Blue whale silence is not abstract. It is a biological signal, a loss of rhythm and a break in the system.
These are animals that once boomed across entire ocean basins. They carry the memory of the seas on timescales longer than we can fathom. When they go quiet, it means something foundational has shifted. Fewer prey. Altered chemistry. Ecological stress echoing across species and generations.
Silence, in this case, is depletion and a warning.
We still tend to see whales as symbols, of majesty, of recovery, of a planet we might one day protect properly. Yet their silence shows how fragile those symbols are when we ignore the systems underneath.
We are late in the story, but we are not too late to listen.
The hydrophone didn’t reveal the problem. It revealed how long it had been building. If we wait for silence, we’ve already waited too long.
If this story resonated, feel free to share it with someone who needs to remember the ocean too. You can also subscribe to Ocean Rising to get weekly dispatches from the deep.
– Luke
I find your posts fascinating and informative. I so love exploring things I Donny have a lot of knowledge about. Thank you, Luke, for sharing their world!