Underwater recording devices, anchored to cement blocks on the Hudson River floor, spent weeks collecting audio from the murky depths during spring and summer 2021. Researchers expected silence. Atlantic sturgeon — armored, prehistoric, unchanged for 100 million years — had never been known to make a sound.
What came back through the recordings stopped them cold: nearly 7,700 low, reverberating rumbles, described by one scientist as the metallic strike of a kettledrum echoing underwater. A fish that outlasted the dinosaurs had, apparently, been making noise all along.
A prehistoric fish finally breaks its silence
Atlantic sturgeon have patrolled Earth’s rivers for roughly 100 million years — surviving whatever wiped out the dinosaurs, enduring ice ages, outlasting countless species. Yet no one had ever documented them making a sound. That silence ended with this study.
The research team chose their recording site carefully. Hyde Park, New York, on the Hudson River, is believed to host the largest known Atlantic sturgeon spawning aggregation in the United States. Underwater devices, anchored to cement blocks, captured 31 days of audio across spring and summer 2021.
Nearly 7,700 individual low-frequency rumbles emerged from those recordings, peaking around 44 hertz — close to the lower threshold of human hearing. The sounds were completely absent in April, before the fish arrived. By June and early July, at the height of spawning season, the rumbles had built into a full underwater cacophony.
What ‘thunder’ sounds like underwater
Lead researcher Rebecca Cohen, a bioacoustics scientist at the Cornell Lab of Ornithology, describes the sounds as resembling a metallic timpani kettledrum. “You can hear pulses like someone is striking a drum,” she says, “and this continuous rumble around each pulse.” The name the team settled on — “thunders” — fits both the acoustic quality and the sheer collective volume of thousands of rumbles layered on top of each other.
Getting to that clean signal wasn’t simple. Cohen had to filter out interference from nearby trains and percussive thuds produced by freshwater drum fish — a nonnative species sharing the same waters. To confirm the source, the team recorded captive Atlantic sturgeon held in a tank at a National Fish Hatchery in South Carolina, and the sounds matched those from the Hudson River exactly.
More than sound: what the rumbles may mean
Dennis Higgs, a biologist at the University of Windsor who wasn’t involved in the study, believes these thunders may function as communication signals during spawning. They aren’t just auditory, he notes — they’re physical. When spawning lake sturgeon produce a similar rumble, the vibration ripples through the surrounding water. “The females likely hear and feel the water,” Higgs says, “telling them the male is ready to spawn.”
This matters acutely in the Hudson River’s murky conditions, where visibility is essentially zero. A felt vibration could be the most reliable signal available for coordinating fertilization. Higgs previously found that lake sturgeon produce a comparable thunder-like sound, which suggests this trait may be shared across sturgeon species more broadly.
A new tool for saving an endangered species
Every U.S. population of Atlantic sturgeon is currently listed as endangered or threatened, the result of centuries of overfishing and habitat destruction. Protecting them requires knowing where and when they spawn — which has historically meant nets and acoustic tags, both requiring physical handling. For a protected species, that handling causes real stress.
Passive acoustic monitoring offers a different path entirely. By simply listening, researchers can track spawning activity without touching a single fish. Cohen sees this as a meaningful shift in how conservation monitoring can work — listening for thunders could help wildlife managers identify productive spawning locations, estimate population sizes, and track whether conditions are improving, all without disturbing the animals they’re trying to protect.
Noise pollution and the fragile future of sturgeon
That sensitivity to sound cuts both ways. Arthur Popper, a bioacoustics biologist at the University of Maryland, tracked sturgeon in another section of the Hudson during bridge pile-driving construction. The fish actively avoided the area while work was underway, then returned once it stopped. “It’s clear the animals are capable of hearing something,” Popper says.
Industrial noise near spawning grounds isn’t a minor inconvenience. It could disrupt breeding behavior at exactly the moment population recovery depends on it, and filtering out human-made noise to better monitor sturgeon isn’t just a technical challenge — it’s a conservation priority.
A river loud with sturgeon thunder may be one of the clearest signs that a freshwater ecosystem is genuinely healthy, since sturgeon only spawn in clean water. For a species that survived 100 million years, their sound may now be one of the most useful things they’ve ever given us.
If you want to learn more about these findings, you can check the full study here: Cohen RE, Baker PJ, Bowser CH, Breece MW, Flecker AS, Fox DA, Henne JP, Higgs AL, Niemistö ML, Pendleton RM, Sethi SA, White SL, Rice AN (2025) Sounds of Atlantic sturgeon spawning: first description and opportunities for riverine endangered species conservation with passive acoustic monitoring. Endang Species Res 58:1-14 https://doi.org/10.3354/esr01429