The world’s largest animal is growing quiet, and scientists say it’s a warning we can’t ignore. A series of new studies, including a major six-year acoustic survey published in PLOS ONE on August 8, 2025, reveal that blue whales—those gentle giants stretching up to 100 feet and weighing as much as 200 tons—are singing less than ever before. From the coast of California to the far reaches of the Pacific, the ocean’s most iconic voice is fading, and the silence carries troubling implications for marine life and the planet as a whole.
Researchers from the Monterey Bay Aquarium Research Institute (MBARI), led by biological oceanographer John P. Ryan, spent six years monitoring blue, fin, and humpback whale songs using a hydrophone anchored 3,000 feet deep off the California coast. Their project kicked off in 2015, just as a catastrophic marine heatwave known as ‘The Blob’ engulfed more than 2,000 miles of the Pacific Ocean. The results were startling: blue whale vocalizations dropped by nearly 40 percent during food-scarce years, a direct response to the near disappearance of krill—the tiny, shrimp-like crustaceans that make up their exclusive diet.
“When you really break it down, it’s like trying to sing while you’re starving,” Ryan told National Geographic. “They were spending all their time just trying to find food.” The study found that while humpback whales, able to switch between krill and fish, continued to sing, blue and fin whales grew silent in times of scarcity. The pattern was clear: whale song detection correlated directly with krill population data and ecosystem stress indicators.
But why does this matter to anyone outside the marine biology world? Whale song isn’t just a quirky curiosity—it’s a vital sign of ocean health. Blue whales use their powerful, low-frequency calls to navigate, maintain social bonds, and attract mates across vast, dark expanses of ocean. These songs can travel for miles, helping whales coordinate feeding and mating activities. When blue whales go quiet, it signals more than just a loss of sound; it’s a sign that the ocean’s intricate food web is unraveling.
Oregon State ecologist Dawn Barlow summed it up: blue whales are “ecosystem sentinels.” When these long-lived, wide-roaming animals stop singing, “it’s not just their problem—it’s ours too,” she told National Geographic. Their silence reflects broader environmental shifts, with ramifications that ripple through the entire marine ecosystem.
Marine heatwaves like The Blob are becoming more frequent and severe. A 2025 study found that the average duration of ocean heatwaves has tripled since the 1940s, and today’s events can be up to 5°C hotter than historic norms. These temperature spikes devastate krill populations, forcing blue whales to spend more time foraging and leaving them with little energy for vocalizations. The loss of their songs is a red flag: a sign that the foundation of the ocean food chain is crumbling.
Jarrod Santora, an ecosystem oceanographer and research biologist for the National Oceanic and Atmospheric Administration, put it simply: “Once you truly start listening to how many things make sounds in the ocean, it’s really amazing what you hear.” But lately, there’s a lot less to hear from blue whales.
The consequences go far beyond the whales themselves. Blue whales are crucial to marine ecosystems not just for their size or appetite—they consume up to four tons of krill daily—but for the way they move nutrients around the ocean. According to the Animal Welfare Institute, “Whale fecal plumes contain valuable nutrients like iron, nitrogen, and phosphorus. They stimulate production of microscopic marine algae, or phytoplankton, which form the base of many aquatic food chains. Whales also transport nutrients in their fecal plumes, urine, sloughed skin, and placental materials horizontally, a phenomenon referred to as the ‘whale conveyor belt’, as they migrate between nutrient-rich feeding areas and nutrient-limited breeding/birthing areas.”
If blue whales were to disappear, the effects would cascade throughout the marine environment. Many species that depend on healthy phytoplankton populations and the nutrients whales distribute could be at risk. As oceanographer Kelly Benoit-Bird noted, “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.”
Climate change isn’t the only culprit in the whales’ growing silence. Human-made noise from shipping, drilling, and industrial operations has created what scientists call a “sonic haze” in the ocean, further disrupting the acoustic environment that whales rely on. This noise pollution interferes with navigation, communication, and foraging, making it even harder for whales to connect and thrive. As the PLOS ONE study and MBARI researchers emphasize, the combination of warming seas and rising noise levels is a double blow to these vulnerable giants.
During the COVID-19 lockdowns, ocean noise dropped dramatically as global shipping slowed. Whale activity increased, providing a rare glimpse into how much human noise affects marine life. “Animals changed their distribution and used the habitat differently when there weren’t humans in those spaces anymore,” Benoit-Bird observed.
With these mounting challenges, scientists are calling for new approaches to monitoring and protecting ocean health. Passive Acoustic Monitoring (PAM)—a global network of underwater listening stations—could help track changes in whale behavior and, by extension, the state of marine ecosystems. As the PLOS ONE paper notes, whale song could become a powerful biological sensor for climate change, fisheries management, and ecosystem conservation. “Surprisingly, the acoustic behavior of baleen whales provides insights about which species can better adapt to changing ocean conditions. Our findings can help resource managers and policymakers better protect endangered whales,” Ryan explained in the study.
There are currently between 10,000 and 25,000 blue whales alive in the world’s oceans, but their future is far from assured. Over three million were killed for oil in the 1900s, and today’s threats—climate change, food shortages, and noise—are no less daunting. The increasing silence of blue whales is a powerful conservation signal, one that demands urgent action from policymakers and the public alike. Efforts must focus not only on direct threats like hunting and entanglement, but also on addressing the broader ecological factors—climate change, habitat protection, and noise reduction—that shape whale behavior and survival.
As scientists listen ever more closely to the fading songs of blue whales, they’re not just eavesdropping on a vanishing world—they’re tuning in to the health of the planet itself. If the largest, loudest creatures in the ocean are forced to grow silent, it’s a message we can’t afford to ignore.
