The 52 Hz whale, ‘the loneliest in the world’, and the blue whales singing ever deeper since 1963

What is the 52 Hz whale?

During the Cold War, the US Navy laid arrays of hydrophones on the Pacific floor, called SOSUS, to listen for submarines. Biologists later got to work on some of the recordings. William Watkins and his team at Woods Hole, Massachusetts, found in them a series of calls they could not match to any species: tones of three to ten seconds, in groups, strongest at around 52 hertz. They first noticed them in 1989; from 1992 they tracked them season by season.

In 2004 the team published what 12 years had shown. Only one series of calls was ever heard at a time, never two overlapping, which suggested a single whale. The tracks, from 708 to 11,062 kilometres a season, did not follow the blue, humpback or fin whales heard on the same hydrophones. And one short sentence that still stands: the species producing these calls is unknown. Watkins died in September 2004, before the paper came out.

Both recordings are NOAA PMEL's, from the northeast Pacific, played here 20 times higher than in the sea. The 52 Hz clip is undated; its note measures about 50 Hz.

Is it really the loneliest whale in the world?

The word ‘lonely’ is not in the 2004 paper. The story is: in December 2004 The New York Times wrote about an animal roaming the ocean year after year and getting no reply. The phrase ‘the loneliest whale in the world’ spread later; the oldest dated use we found is from 2012, and its exact origin is unknown.

What the data support is less dramatic. Its voice was the only one of its kind on the Navy arrays, but nothing shows the whale is cut off: 52 hertz is not a frequency other whales cannot hear. Christopher Clark of Cornell University, who recorded it in 1993, said in 2015 that blue, fin and humpback whales ‘can hear this guy, they’re not deaf’; the voice is just odd. Kate Stafford, who studies blue whales, noted that it had survived at least 12 years in good shape, and that its seasons and migration pattern match those of blue whales, even though Watkins found its individual tracks unrelated to theirs.

The rest is hypothesis. That it is a hybrid of a blue and a fin whale, as often written, has not been confirmed: as of 2015, nobody had managed to record a hybrid’s call. That several whales may share the voice was suggested by John Hildebrand of Scripps in a 2015 interview: calls of the same type, found in 2010 recordings off California, reportedly appeared at the same time on two widely separated sensors. The observation has not been published in a scientific journal.

Why are blue whale songs getting deeper?

The 52 Hz story hid the other one. In 2009 Mark McDonald, John Hildebrand and Sarah Mesnick gathered blue-whale recordings from around the world, some from the 1960s, and measured the note of each song. In the northeast Pacific the base note of the B call fell from 21.9 Hz in 1963 to 15.2 Hz in 2008, by 31%. All seven song types with measurements across several years were falling, each at its own rate. And within one year, different whales in the same region sang the same note, to within 3%.

The California measurements went on. Rice and colleagues published 2006–2019 in 2022: the note keeps falling, more slowly, about 0.27 Hz a year at the measured harmonic against 0.4 up to 2008. In 2019 the base note was 14.2 Hz, below the 20 Hz where human hearing usually begins.

The explanations tested so far do not all fit:

Rice and colleagues raise a stranger idea too: the whales may not even perceive the small, steady adjustments they make through each season, and the descent may be an unintended side effect of the way they keep their songs in tune with each other. Their conclusion: no theory so far explains all of it.

How many blue whales were killed?

The oldest blue-whale song recordings in McDonald’s study date from 1959 (North Atlantic), and those of the northeast Pacific song from 1963, just as industrial whaling was ending: blue whales were protected from 1966, though Soviet ships kept killing them illegally into the early 1970s. In the 20th century 379,185 blue whales were caught, by the count of Rocha and colleagues (2014), almost all in the southern hemisphere.

How many blue whales live in the northeast Pacific today is not known for sure. The latest photo-identification estimate for the US West Coast is 1,898 in 2018, and NOAA’s 2023 report says the population trend is unknown and that ships probably kill more whales than the limit NOAA considers sustainable for this population.

Where is the 52 Hz whale now?

Watkins’s published tracking series ends with the winter of 2003–2004; the 2010 detection was only described in an interview. Whether it is alive is unknown, and so is its sex.

One thing changed in this voice too: over 15 years its note slid from about 52 Hz to close to 50 Hz, according to Watkins. In 2015 Hildebrand expected it to be nearer 47 Hz by then, though no recording had been identified for a few years. In proportion, that is less than the blue whales dropped over the same years: about 4% against about 12%. Whether the cause is the same, nobody has studied.

We do not know whether anyone ever answered it. We do know it did not sing into a silent ocean: every year, the blue whales of a region tune to one another, and their note fell over more than five decades of measurements. The voice called the loneliest in the world went down too.