Name that tuna

It’s easy to assume that the aquatic world is peaceful and quiet. Submerged sounds generally bounce off the waterline and return to where they came from. But the sea is full of sound. The natural ocean soundscape is a blend of geophony – the noises made by swirling, crashing water and the occasional subsea earthquake – and biophony, the sounds made by living things. The latter is the subject of Sing Like Fish, the science writer Amorina Kingdon’s exploration of how marine animals make, sense and use sound. From snapping shrimp that hunt with lethally popping bubbles to humpback whales that sing songs on repeat, non-stop, for twenty-four hours at a time, she recounts enough absorbing facts to disprove thoroughly the idea that sound is of little consequence for sea life.

With a focus on her home waters off the coast of British Columbia, Kingdon sets off, hydrophone in hand, to eavesdrop on the local fish life and meet experts dedicated to learning more about the ocean’s biophony. She hears the male midshipman, a type of toadfish that hums loudly by contracting powerful muscles 100 times a second for an hour or two, setting its gas-filled swim bladder aquiver. It’s a show of stamina, demonstrating to female midshipmen that he will do a good job of guarding the nest of her unhatched eggs if picked as a mate. For their part, the females adjust their auditory range during the mating season to better hear the males’ harmonics.

“Fish sounds”, Kingdon writes, “are a window into lives.” And so many of those lives remain mysterious. In 2003, when the aquatic acousticians Rodney Rountree, Katie Anderson and Francis Juanes lowered a hydrophone into the Hudson River off Pier 26 in New York, they recorded forty-four sound types, of which three were human-made, two from known fish and the rest unidentified voices, probably invertebrates whose sonic worlds are the least studied.

Close to 1,000 sonic fish species have so far been “auditioned”, in many cases by the aptly named Marie Poland Fish, a scientist at the University of Rhode Island. In the 1960s, she travelled the US coasts with a car full of waterproof recording gear and a foldable aquarium tank, catching fish and listening to their voices. This esoteric pursuit was funded by the US military, who were keen to know what they were hearing on their new arrays of underwater listening stations. It’s no surprise that much aquatic acoustic research is driven by humancentric conundrums. How far away is that iceberg? Is that blip on the hydrophone a Soviet submarine or a whale? Do noisy fishing boats scare off the fish they’re trying to catch?

Unavoidably, darker themes run through Sing Like Fish. Many breakthroughs in understanding the complex acoustic lives of marine mammals have come from the grim tanks of amusement parks and military research facilities. In the 1930s, when fishermen in Florida started rounding up dolphins for public displays, they noticed that the animals avoided fine-meshed nets, even in murky water. In contrast, they blundered straight into nets with bigger gaps. This gave scientists the idea that cetaceans use beams of sound to see, as bats do, and that their sonar doesn’t pick up the wider-meshed nets.

Kingdon describes a heartbreaking study of a male beluga whale born in captivity and the devoted scientist who listened through the early days of his life as he babbled like a baby human, before gradually learning from his mother how to talk beluga. When dolphins are kept in isolation in captivity, their signature whistles – calls unique to each individual like names – shoot up from the regular 50 per cent to about 90 per cent of the noises they make. The lonely, captive animals are shrieking: “Here I am!”

Humans are, of course, messing with the sounds of the sea. The destructive din of seismic air guns searching for subsea oil and gas deposits mixes with the clamour of shipping. Bubbles spin off propellers and collapse, meaning vessels are similar to snapping shrimp, only much bigger and louder.

Scientists are still learning about the impacts of oceanic noise pollution, but already we know that it makes deep-diving whales rush perilously for the surface, as well as causing dizziness in lobsters and disarray among plankton. Gains in quietness from engineering tweaks are swamped by the growing size of ships and the skyrocketing volume of shipping. “The culprit is our way of life: oil, consumer goods, even cruise ships”, says Amorina Kingdon. “We cannot bemoan the noisy ocean and order all our household goods online.” Noise pollution, she makes clear, is not the worst problem facing the ocean, but it adds one more stress to already overstressed, overhunted and overheated sea life.

Helen Scales is a marine biologist, writer and broadcaster. Her books include What the Wild Sea Can Be, 2024, and The Brilliant Abyss, 2021. She teaches at the University of Cambridge

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