Photo: Nick Ut / AP.
A blue whale, the largest mammal on Earth, surfaces in the Pacific Ocean near Long Beach, California.
Whether we’re talking about Jonah and the whale or Pinocchio or the lobster fisherman’s uncomfortably close encounter in 2021, we humans have always been fascinated by the largest mammals on Earth. And the blue whale is the most massive of them all. But what is going on with Leviathan of late?
Shola Lawal writes at Al Jazeera that it is not singing as much as it used to.
“Unlike our musical sounds, those produced by whales are a complex range of vocalizations that include groans, clicks and whistles and that can sound like anything from the mooing of a cow to the twitter of a bird. These vocalisations can be so powerful that they can be heard as far as 10km (6 miles) away, and can last for half an hour at a time. …
“For researchers, these complex sounds are a window into whale behavior, even if humans don’t yet know exactly how to decode them.
“The frequency of songs and their intensity can signal various things: an abundance of food, for example. In recent studies, however, researchers have been alarmed to find that blue whales, the largest whales and, indeed, the largest mammals on Earth, have stopped singing at specific times.
“Their eerie quietness, scientists say, is a signal that ocean life is changing fundamentally. The most recent study, conducted by scientists from the Monterey Bay Aquarium Research Institute in California in the US and published in February, examined three types of whales. Researchers found that blue whales, in particular, have become more vulnerable to this change.
“Whale songs are critical for communication between males and females when mating and among schools of whales migrating. …
“The first study, conducted in the sea waters between the islands of New Zealand between 2016 and 2018, was led by scientists from the Marine Mammal Institute at Oregon State University in the US. Over that period of time, researchers tracked specific blue whale vocalizations linked to feeding (called D-calls) and mating (called patterned songs).
“Researchers used continuous recordings from underwater devices called hydrophones, which can log sounds over thousands of kilometers, and which were placed in the South Taranaki Bight – a known foraging spot for blue whales off the west coast of New Zealand.
“They discovered that during some periods, particularly in the warmer months of spring and summer when whales usually fatten up, the frequency and intensity of sounds related to feeding activity dropped – suggesting a reduction in food sources. That decline was followed by reduced occurrences of patterned songs, signaling a dip in reproductive activity.
” ‘When there are fewer feeding opportunities, they put less effort into reproduction,’ lead researcher Dawn Barlow told reporters. The results of that study were published in the journal Ecology and Evolution in 2023.
“Then, in a study published in the scientific journal PLOS One in February [2025] researchers tracked baleen whale sounds in the California Current Ecosystem, the area in the North Pacific Ocean stretching from British Columbia to Baja California. Blue whales are a type of baleen whale, and the study focused on them, alongside their cousins, humpback whales and fin whales.
“Over six years starting in 2015, the scientists found distinct patterns. Over the first two years, ‘times were tough for whales,’ lead researcher John Ryan, of the Monterey Bay Aquarium Research Institute in California, noted in a press statement, as the whales, particularly blue whales, were found to be singing less. Over the next three years, however, all three whale species were back to singing more frequently, the study noted.
“Both studies found one main reason for the reduction of whale song: food or, in this case, the lack of it. It turns out that the research, conducted between 2015 and 2020, captured periods of extreme marine heatwave events that killed off krill, the small shrimp-like animals that blue whales feed on.
“Those heatwaves are part of a looming environmental catastrophe … caused by high-emission human activities, chief among them being the burning of fossil fuels. …
“Krill, which blue whales primarily feed on, are highly sensitive to heat and can all but vanish during heatwaves, the studies found. Their movement patterns also change drastically: instead of staying together, as they usually do, krill disperse when it is hot, making them harder for predators like blue whales to find.
“Typically, when foraging, blue whales sing to others to signal that they have found swarms of krill. … Heatwaves can also trigger harmful chemical changes in the oceans that encourage the growth of toxic algae, which causes poisoning and death to mammals in the oceans and sea birds, researchers have previously found, suggesting that blue whales are also at risk of being poisoned.
“In the more recent study in California, researchers found that in the first two years when whales were singing less frequently, there was also a reduction in other fish populations. …
“ ‘Compared to humpback whales, blue whales in the eastern North Pacific may be more vulnerable due to not only a smaller population size but also a less flexible foraging strategy,’ Ryan, the lead author of the California study said in a statement. …
“It is likely, both studies say, that blue whales need to spend more time and energy finding food when it is scarce, instead of singing.”
At Al Jazeera, here, you read about climate change effects on other species, too.
Photo: CoD Newsroom/Flickr
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