Scientists Finally Know What Caused the Eerie Clicking Sound Thousands of Feet Beneath the Pacific Ocean

An enigmatic noise thousands of feet deep into the ocean off the coast of Central California has been a subject of mystery for many experts. Researcher Will Oestreich, a U.S. National Science Foundation postdoctoral fellow at the Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, observed the strange clicking sounds captured by a hydrophone stationed on the ocean floor and runs along the continental slope in the region. At first, Oestreich found himself clueless about the source of the sounds but eventually concluded it to be the echolocation of sperm whales. 

The researcher told SFGATE in October 2024, “It almost sounded like a human machine.” He revealed that the clicking sounds began slowly but kept getting faster before developing into a continuous creak sounding similar to a television static noise. The official YouTube channel for MBARI (@MBARIvideo) shared the recording of the clicking sounds at the lab’s cabled underwater observatory at a depth of 891 meters in March 2024. Eventually, Oestreich realized that the noise was, in fact, the echolocation of several endangered sperm whales hunting for prey deep in the ocean. He also noted the rarity of the occurrence as these ocean predators were not generally found in the region. 

Oestreich explained that while sperm whales are widely spread throughout the ocean, they are usually difficult to spot and observe because of their deep-sea habitats. “We were recording a sound of a highly cryptic species, and it made us wonder: How regular is this? Were we lucky, or is this happening more regularly than we thought?” the researcher pondered. While sperm whale sightings are rare, their sounds are heard far and wide as they can reach over 200 decibels underwater– the loudest animals on Earth. They also highly rely on sound to search for food within the darkness of the deep sea. 

Additionally, the hydrophone or underwater microphone can capture sound waves of about 256,000 times per second from 100 miles away. It can record sounds with frequencies that are way higher or lower than human ears can withstand. “It’s a really cool tool for us researchers because they’re telling us things about their own lives. They’re a top apex predator — tigers of the deep sea — and their behavior reflects a food web that’s difficult for us to study,” the postdoctoral fellow at the lab elucidated. Interestingly, the spacing between each clicking sound indicated the size of the whale’s body. This fact allowed the researchers to identify whether they were hearing sounds of adult males, females with babies, or teenage whales. 

The findings and observations of the research proved that the endangered species were unusually frequenting through Monterey Bay and raised doubts about their seasonal migration patterns, as per the study published in the journal Movement Ecology. Oestreich, who had been tracking the sonic behaviors of whales– mainly blue and fin whales, for the past seven years, shared that they had tracked the sperm whales’ presence on 1,242 days during the time period. The experts hope the research will be useful in studying sperm whales and their response to warming climates, changing ecosystems, and how it affects their prey availability in the Pacific Ocean. 

You can follow @MBARIvideo on YouTube for more interesting underwater facts and occurrences.