Ithaca, N.Y — Researchers from FishEye Collaborative, a conservation-technology nonprofit, Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics, and Aalto University developed a new tool that combines underwater sound recording and 360° video to pinpoint the sounds made by individual fish. The findings were published today in the journal Methods in Ecology and Evolution.

Ecologists often use underwater microphones to monitor the health of marine environments, such as coral reefs. Underwater ecosystems are filled with thumps, pops, and snaps from shrimp and fish.

But until now, ecologists have largely been unable to interpret these sounds to a species level because reefs are crowded with hundreds of different species, very few of which have had sounds accurately attributed to them.

“When it comes to identifying sounds, the same biodiversity we aim to protect is also our greatest challenge,” explains Marc Dantzker, lead author of the research and Executive Director of FishEye Collaborative. “The diversity of fish sounds on a coral reef rivals that of birds in a rainforest. In the Caribbean alone, we estimate that over 700 fish species produce sounds.”

Now, a new tool developed by researchers called an Omnidirectional Underwater Passive Acoustic Camera (UPAC-360) can identify the sources of individual fish sounds. The new tool combines 360° camera with underwater microphones, what scientists call hydrophones, to accurately identify fish through sound.

“Spatial Audio lets you hear the direction from which sounds arrive at the camera,” explained Dantzker. “When we visualize that sound and lay the picture on top of the 360° image, the result is a video that can reveal which sound came from which fish.”

The team identified 46 fish species from the coral reefs of Curaçao in the Caribbean–more than half of these species were never known to make sound.

The research findings represent the most extensive collection of fish sounds ever published. The growing collection is available to everyone at fisheyecollaborative.org/library.

The researchers say that identified sounds from the library can be used to automatically train machine learning systems to detect fish species in underwater recordings. The technology is similar to smartphone apps like the Cornell Lab of Ornithology’s Merlin Bird ID that automatically identifies bird species by song or call. “We are a long way from being able to build ‘Merlin’ for the oceans, but the sounds are useful for scientists and conservationists right away,” says Aaron Rice, a senior author of the study and principal ecologist at the Cornell Lab.

Dantzker adds, “By identifying which species make which sounds, we’re making it possible to decode reef soundscapes, transforming acoustic monitoring into a powerful tool for ocean conservation.”

With many coral reefs in decline due to climate change, pollution, and overfishing, the authors note that new technologies are needed to help support conservation decision making.

“These reefs are declining rapidly, threatening not just biodiversity, but also the food security and livelihoods of nearly a billion people who depend on them,” said Dantzker. “In response, governments and NGOs are investing billions in reef protection and restoration. That’s not enough, so we must ensure that we spend these limited funds effectively. We need to track how reefs are responding both to the stressors and the interventions.”

“By discovering the identity of these hidden voices, acoustics will become a powerful indicator of reef health and resilience and a strategy to monitor wider and deeper,” said Matt Duggan, co-author and PhD candidate at Cornell.

Another strength of the technology is that it can be placed in reefs and left to collect data without the need for a diver or boat to be present. “The fact that our recording system is put out in nature and can record for long periods of time means that we’re able to capture species’ behaviors and sounds that have never before been witnessed,” said Rice.

Although the results are the most extensive collection of such fish sounds ever published, they still represent a fraction of the total species in the reef. The researchers say that this technique opens the door to decoding the whole reef. They’re expanding the research, growing the library for the Caribbean, and broadening their efforts to other reefs around the world, including Hawai’i and Indonesia, in the coming months.

The Cornell Lab of Ornithology is a nonprofit, member-supported organization dedicated to the understanding and protection of birds, wildlife, and our shared planet through research, education, participatory science, and conservation. The mission of the Cornell Lab of Ornithology is to interpret and conserve the earth’s biological diversity through research, education, and citizen science focused on birds.