What If We Could Help Marine Conservation by Listening to Fish?

This article summarizes methods and findings from FishEye Collaborative’s peer-reviewed paper, "Deciphering complex coral reef soundscapes with spatial audio and 360° video" (Dantzker et al., 2025) published in Methods in Ecology and Evolution (https://doi.org/10.1111/2041-210X.70149), which introduces a scalable approach to species-level fish sound identification in the wild—marking a significant advance in the use of passive acoustic monitoring (PAM) for marine biodiversity research. A presentation based on this work,“Who Said That? Deciphering Complex Coral Reef Soundscapes with Spatial Audio and 360° Video,” was given at the Acoustical Society of America invited symposium “Progress on Bioacoustics of Fish” on May 19, 2025. 

 

Introduction: Soundscapes Hold Answers—If We Can Understand Them

Coral reefs are among the most acoustically active ecosystems in the ocean. It’s likely that most reef-associated fishes are capable of producing sound, and these sounds hold valuable insights about biodiversity, behavior, and ecosystem health. Passive acoustic monitoring (PAM) offers a non-invasive method to access this information at scale. But until now, one critical piece has been missing: the ability to consistently identify which fish are making which sounds.

The Identification Gap: Why Fish Sounds Are Hard to Match to Species

Despite widespread use of PAM in marine systems, most recorded fish sounds can’t be confidently tied to a species. Many known examples come from captive settings, where sounds are often produced under duress. In natural reef environments—where dozens of species may be present in a single recording—identifying who is making each sound has proven difficult. Existing methods, including diver observations and directional cameras, often fall short due to limited visual range, high disturbance, or the potential that the sound you are recording isn’t coming from the animal you can see. Some systems have overcome some of these limitations, but progress has been slow and the dizzying diversity and abundance of coral reefs makes them especially challenging.

This lack of species-level identification limits what researchers and marine managers can do with their sound recordings. Without knowing which species are present, acoustic recordings rely on abstract and often unverified statistical measurements.

A New Approach: Combining Spatial Audio and 360° Video

FishEye Collaborative has developed a scalable approach for in situ fish-sound identification on complex coral reefs. The system, called the UPAC-360 (Omnidirectional Underwater Passive Acoustic Camera), pairs a compact  array of hydrophones with a 360° video camera to create a synchronized, immersive view of the soundscape. Using spatial audio processing and ambisonics algorithms, researchers can visualize the direction of individual sounds and overlay those signals on video footage.

This allows researchers to pinpoint the source of a sound with enough precision to assign it to a visible individual, even in busy reef scenes with overlapping species and movement.

Field Results: First Natural Sound Identifications for 46 Fish Species

Over the course of four days in Curaçao, the FishEye team recorded more than 20 hours of reef activity using the UPAC-360 system. The analysis takes far more time, effort, and expertise, however FishEye Collaborative has established workflows that have accelerated the process. From the four days’   recordings, we identified and ascribed natural sounds to 46 species of Caribbean reef-associated fishes.

Of the 46 reef-associated fish species with sound identifications in this study, none had publicly available natural sound recordings prior to this work. Twenty-one had previously been recorded under duress in captivity, one had been recorded in captivity without additional stressors, and five had been documented in literature but with no accessible recordings. The remaining fishes had never been recorded at all. This makes the FishEye dataset the largest publicly available source of natural, behaviorally grounded recordings for these species.

In some cases, the sound source could be narrowed to a single individual based on the spatial detection zone. In others, behavioral cues—such as territorial displays, jaw clicks, or synchronized movements—added weight to the identification. These verified recordings are now available through FishEye’s open-access reference library at FishEyeCollaborative.org/library, supporting broader PAM research across the region and beyond.

Why It Matters: New Capabilities for Biodiversity Monitoring and Conservation

Species-specific sound data significantly enhances the value of passive acoustic recordings. With accurate identifications, PAM systems can move beyond abstract indices and begin delivering more concrete conservation insights. These include presence/absence data for key taxa, early detection of invasive or indicator species, and the ability to monitor behaviors like spawning or feeding.

The verified sound library also provides the essential training material needed to develop machine learning models for large-scale audio analysis. These models can process months or years of data, making it possible to track ecological patterns at high temporal and spatial resolution—something visual surveys or eDNA approaches often cannot match.

Looking Ahead: Scaling the Approach for Global Application

With over 1,100 fish species on Caribbean coral reefs, 46 might seem like a small fraction. But in terms of natural, in situ recordings linked to known species, it’s unprecedented. This is the largest dataset of its kind—and for FishEye, it’s the start of a much broader campaign of biodiversity listening.

Because fish sounds can vary by geography, depth, and population, expanding the reference dataset will require broader sampling and continued iteration. FishEye’s approach is designed to be scalable. The UPAC-360 system is compact, field-ready, and non-invasive, making it suitable for deployment in a variety of marine environments.

As we expand to additional habitats and taxa, we invite collaboration with scientists, regulators, and marine managers who are working to improve the precision of biodiversity assessments in marine protected areas and nearshore ecosystems. The goal is to create an integrated approach—one that combines traditional and acoustic data—to inform evidence-based conservation.

Conclusion: Listening More Closely to Life on the Reef

Reefs have always been full of sound—we just haven’t had the tools to fully understand what we were hearing. This approach represents a step forward in how underwater soundscapes can be interpreted, transforming passive recordings into a verified record of species activity and ecosystem function. With each identified sound, we get closer to a more complete and actionable understanding of reef biodiversity.