Can Fish Talk?   

   American submariners and sonar operators, listening for enemy ships during World War II, were baffled by what they heard. The USS Salmon surfaced to look for a ship whose "rumbling propellers" did not exist. 

   Sailors of the USS Tarpon heard "repetitive clanging," and on the USS Permit they heard "hammering on steel." In the Chesapeake Bay, a sailor compared the sound to "pneumatic drills tearing up a concrete sidewalk." 

   So much for Cousteau's "silent world."  

   After the war, the Navy began to investigate, choosing a scientist, Marie Poland Fish, who would found the field of marine bioacoustics. She reviewed reports of "beeping, clicking, creaking, harsh croaking, crackling, whistling, grunting, hammering, moaning, mewing," even the "dragging of heavy chains." There was even a 19th century sailor who heard "jingling bells, enormous harps" and the "siren songs" of Homer's story. 

   Sound waves travel through water five times faster than through air. Ms. Fish began collecting subjects for experiments. By 1954, using hydrophones, she had studied more than 180 species, eels (bubbling put-put), sea bream (guttural thumps), sculpin (humming generators), sea horses (snapping fingers), herring (knocks), hardtails (rasps), bass (grunts), and toadfish (fog horns). 

   Some species were multitalented. Chattiest was the sea robin (cackling and clucking like a barnyard fowl). 

   Scientists were able to identify anatomy in some cases. Finfish vocalize by grinding their jaws. The toadfish "vibrates muscles against their air bladders." A spawning group of croakers could raise the ocean's background volume to 114 decibels - rock concert level. 

   The Navy uses this knowledge to train sonar operators to distinguish between enemy vessels and false targets. Except for the growling sound of toadfish in breeding season, guarding their eggs, little is known about languages. 

   Today, sonar, industrial shipping and explosive surveys for oil and gas drown out the creatures. Man made noise has fatally disoriented whales and killed young fish. There are studies to understand how humans distort marine soundscapes. 

   As the pandemic interrupted life on land, the effect of reduced shipping allowed creatures over three quarters of the earth to be heard once again.

 Smithsonian