Among the many puzzles that confronted American sailors during World War II, few were as vexing as the sound of phantom enemies. Especially in the war’s early days, submarine crews and sonar operators listening for Axis vessels were often baffled by what they heard. When the USS Salmon surfaced to search for the ship whose rumbling propellers its crew had detected off the Philippines coast on Christmas Eve 1941, the submarine found only an empty expanse of moonlit ocean. Elsewhere in the Pacific, the USS Tarpon was mystified by a repetitive clanging and the USS Permit by what crew members described as the sound of “hammering on steel.” In the Chesapeake Bay, the clangor—likened by one sailor to “pneumatic drills tearing up a concrete sidewalk”—was so loud it threatened to detonate defensive mines and sink friendly ships.
Once the war ended, the Navy, which had begun to suspect that sea creatures were, in fact, behind the cacophony, turned to investigating the problem. To lead the effort it chose a scientist who, though famous in her day, has been largely overlooked by posterity: Marie Poland Fish, who would found the field of marine bioacoustics.
By the time the Navy brought her on board in 1946, Fish was already a celebrated biologist. Born in 1900, Marie Poland—known to friends as Bobbie, on account of her flapper hairstyle—grew up in Paterson, New Jersey, and was a premedical student at Smith College. Upon graduating in 1921, though, she’d turned to the sea to spend more time with Charles Fish, a young plankton scientist whom she’d met while conducting cancer research at a laboratory on Long Island. In 1923, after spending a year as Charles’ research assistant, she took a job with the U.S. Bureau of Fisheries in Massachusetts; that same year, they married.
Marie swiftly proved her gift for ichthyology, becoming a leading expert in the study of fish eggs and larvae. In 1925, she voyaged to the Sargasso Sea on a research trip with the explorer William Beebe, and, from a strange egg scooped up near Bermuda, managed to hatch what she described as a “ribbon-shaped, transparent prelarva” with “enormous fangs.” It was the elusive American eel—and Fish was the first scientist ever to identify one of its eggs. The sea, she declared, had given up a secret, “which it ha[d] jealously guarded for so many centuries.”
The episode made Fish a minor scientific celebrity: “Girl Solves Ancient Mystery,” newspapers trumpeted. (No matter that she was 27 when the discovery was announced.) From 1928 to 1931—the year her daughter, Marilyn, was born—she undertook a biological survey of Lake Erie on behalf of New York State’s Conservation Department, describing the larval stages of species from whitefish to yellow perch. In 1936, she and Charles established a marine lab at the University of Rhode Island, which survives today as the university’s Graduate School of Oceanography. Marie would go on to serve as Rhode Island’s state ichthyologist, and did a two-year stint classifying fish at the U.S. National Museum, now the Smithsonian National Museum of Natural History.
At the Navy’s behest, Fish began to review the voluminous reports that submarines like the Salmon had filed. American sailors, Fish reported, had registered an astonishing array of sounds, including “beeping, clicking, creaking, harsh croaking, crackling, whistling, grunting, hammering, moaning and mewing,” and even “the dragging of heavy chains.”
“It was obvious that animal noises were being encountered,” Fish concluded, though precisely which animals was less clear. As she dug deep into maritime history, she found intriguing records: One 19th-century sailor had wondered at sounds reminiscent of “jingling bells” and “enormous harp[s].” Even the siren songs of Homeric legend, she speculated, may have been produced by breeding schools of croakers.
To Fish, it was clear that ocean creatures were far noisier than anyone had guessed. Sound waves travel through water efficiently—five times faster than through air—but, as Fish hastened to point out, they don’t readily pass between mediums. If observers had merely “pondered a fact which they might have remembered from their physics lessons,” Fish wrote in Scientific American, they might have known to listen more closely. Yet most of Fish’s peers still considered the briny deep a muted realm. When the explorer Jacques Cousteau published his memoir in 1953, he titled it The Silent World. Fish believed that researchers had simply been listening under the wrong conditions. “Even the most loquacious species are usually silenced by the approach of a vessel,” she observed.
She returned to the University of Rhode Island and, using funding from the Office of Naval Research, began to experiment. Fish fenced off a series of enclosures in Rhode Island’s Narragansett Bay and lowered hydrophones into the shallows, which allowed her to spy unobtrusively on marine animals. She also developed more invasive techniques, such as running jolts of electricity through laboratory aquariums in hopes of stimulating a reaction from the fish within. Collecting subjects for these experiments fell to an undergraduate student named Joseph Munro, who went down to the harbor at 5 o’clock each morning to collect live catches from local fishermen. “Any odd fish that came up from the Gulf Stream, we would transfer it to a barrel in the back of the pickup truck and rush back to the university before it died,” Munro recalls in an interview with Smithsonian. He must have done a decent job: In 1952, Munro married Fish’s daughter, Marilyn.
By 1954, Fish had auditioned more than 180 species, from eels (which emitted a “bubbling ‘put-put’”) to sea bream (“guttural thumps”). A vast acoustic library accumulated on Presto recording discs. Fish had a knack for description. Sculpin, she wrote, hummed like generators. Sea horses clicked like a person snapping their fingers. Herring knocked, hardtails rasped, bass grunted. Some species were multitalented: Toadfish honked like “a medley of fog horns” to attract mates during the breeding season, then, upon settling down to guard their eggs, uttered a “loud growling sound” to ward off trespassers. Chattiest of all was the sea robin, a bottom-dweller whose yakking, to Fish’s ears, evoked “the cackling and clucking of barnyard fowl.”
In 1979, the electronic composer Ann McMillan released an album via Smithsonian Folkways, Gateway Summer Sound: Abstracted Animal and Other Sounds, that used all manner of unconventional noises to create spacey songscapes. The first "natural" sounds that McMillan included in her compositions for the album came from Marie Fish's recordings of marine animals.
Fish was not content merely to classify sound. She and her students dissected numerous specimens in search of noisemaking anatomy. Some finfish, she discovered, vocalized by grinding together their jaws or the “pharyngeal teeth” that studded their throats. Porcupinefish, for example, produced a “raspy whine which sounds like a saw or the creaking of a rusty hinge.” Others, like toadfish, vibrated specialized muscles against their air bladders, like drumsticks against a snare. A spawning aggregation of croakers, Fish learned, was capable of raising the ocean’s background volume to 114 decibels—the equivalent of a rock concert. And while the close confines of the lab were ill-suited to studying marine mammals, she correctly hypothesized that whales echolocate, before the phenomenon was first formally described.
Fish’s renown grew, in part because of her voluminous publication record, and in part because of her gender; very few women then worked in marine sciences, never mind led a new discipline. Fish launched sound-collecting expeditions to the Bahamas, the Virgin Islands and Puerto Rico in an era when some institutions still banned women from ocean voyages. (Roberta Eike, a graduate student at the Marine Biological Laboratory in Woods Hole, Massachusetts, was expelled from the program after being barred from expeditions and then stowing away on one in 1956.) Newspapers thrilled to the “affable redhead” with “a sparkling sense of humor” who “eavesdrop[s] on the gossip of sea animals.”
The Navy consulted what Fish called her “underwater detective agency” to identify novel sounds and used her research to train sonar operators to distinguish between enemy vessels and “false targets,” such as whales. She was also dispatched to France, England and Germany to teach allies. A reporter asked whether she’d ever happened to identify a “true target”—a Russian sub. “Yes, but I can’t tell about those,” she said, and changed the subject. In 1966, the year she retired, the Navy gave her a Distinguished Public Service Award, its highest civilian honor. When Fish died in 1989, at 88, a university colleague eulogized her as “by far our most decorated hero.”
Were Marie Fish to drop a hydrophone into the ocean today, she might not like what she heard. Sonar, industrial shipping and explosive seismic surveys for oil and gas increasingly drown out the grunts of croakers and the chuckling of sea robins. The din, known to some researchers as “acoustical bleaching,” has fatally disoriented whales and killed young fish, and the roar of deep-sea mining could soon penetrate even the remotest depths. And while the study of marine bioacoustics is no longer an obscure field, its practitioners have tended to focus on whales and dolphins. “From her time until now, we still know very little about how fish use sound to communicate, not to mention crustaceans,” says Tzu-Hao Lin, an assistant research fellow at Academia Sinica, the national academy of Taiwan.
In 2018, Lin founded the Ocean Biodiversity Listening Project, a global open-access database of marine recordings, captured in environments ranging from sunlit coral reefs to seafloor vents. The project, he says, is a “library that establishes the relationship between sound and fish species,” a compendium that may help other scientists understand how human activities are distorting marine soundscapes. The military, too, has been compelled to carry on Fish’s work: In 2018, after conservation groups sued the Navy over the impacts of its sonar on whales, the government settled the case by creating a program called SanctSound, deploying hydrophones and drones to monitor noise in the Florida Keys, the Channel Islands and other marine sanctuaries.
In 2020, the ocean’s natural soundscapes became newly audible, as the Covid-19 pandemic slowed ship traffic. In Alaska’s Glacier Bay, for instance, biologists have been able to hear the chatter of humpback whales much more clearly. Perhaps Fish would take solace in our renewed ability to hear the snapping of shrimp and click of sea horses—inhabitants, as she put it, of “the once-silent world covering three quarters of the earth’s surface.”
U.S. and Soviet efforts to train dolphins and sea lions for stealth missions met with mixed success
By Ted Scheinman
Marie Fish wasn’t the only marine biologist whose expertise was sought by the armed forces during the Cold War. In one of the most novel initiatives, the United States trained dolphins and other sea creatures to perform a series of extraordinary naval tasks under the Marine Mammal Program. The USSR countered by attempting to train its own aquatic sentries and spies. Military efforts to exploit the intelligence of marine mammals were often ingenious and sometimes successful. Other times they represented a quixotic exercise in interspecies collaboration.
In 1973, the U.S. Navy began its first tests to hide inter-ship communications by using prerecorded pilot whale noises as a mutually intelligible codebook. Sadly, the Navy didn’t know how to project whale sounds at long distances. But in 2018, Chinese researchers published studies indicating that today’s technology allows the long-distance broadcast of coded dolphin and whale songs.
The first military use of a dolphin came in 1965, when the Navy sent a bottlenose named Tuffy (one of his co-workers is pictured here) to deliver messages, tools and even soda to a long-term ocean research module 200-plus feet underwater off the California coast. The Marine Mammal Program’s collection of animals would peak in the 1980s, with more than 100 dolphins plus a bevy of sea lions. The program today continues on a somewhat more modest scale, with dozens of dolphins and sea lions still ready for deployment.
America’s MK6 project took advantage of dolphins’ powerful biological sonar, training them to serve as floating guards around ships. Dolphins performed this task impressively during the Vietnam War. Rumors abound that U.S. dolphins were schooled in anti-personnel attacks, even killing two Soviet divers who were trying to put a mine on a U.S. cargo ship in Vietnam. The Navy has repeatedly denied such claims.
In the 1970s, the Soviets strapped bombs to dolphins and sent them under enemy ships as unwitting suicide bombers; by one estimate, 2,000 dolphins died in such operations. The Soviets also invented a parachute harness for dolphins, so they could drop the creatures into the sea from planes as high as 1.8 miles in the air. With titanium clamps they carried on their noses, Soviet dolphins could lock a small sphere, roughly the size of a golf ball, onto an enemy (human) swimmer, thus injecting a lethal dose of carbon dioxide.