What noise does a fish make? New underwater tool lets ecologists ID fish from their sounds

Researchers from Fisheye Collaborative, a non-profit organization for conservation-technology, Cornell University and the University of Aalto have developed a new tool that combines a underwater sound recording and a 360 ° video to identify the sounds made by individual fish. The results are published in the journal Methods in ecology and evolution.

Ecologists use underwater sound recorders to monitor marine environments such as coral reefs. These recorders capture dense sound landscapes filled with blows, pop and shrimp and fish shots.

But so far, environmentalists have largely missed the capacity to interpret these sounds at a level of species because the reefs are congested with individuals of hundreds of species, which very few have had precise sounds.

“When it comes to identifying the sounds, the same biodiversity that we aim to protect is also our biggest challenge,” said Dr. Marc Dantzker, principal author of research and executive director of Fisheye collaborative. “The diversity of fish sounds on a coral reef rivals that of birds in a tropical forest. In the Caribbean only, we estimate that more than 700 fish species produce sounds.”

Now, a newly developed tool that researchers calls a passive omnidirectional submarine camera (UPAC-360) have enabled them to identify the sources of individual sounds and attribute them to 46 species of fish from the coral reefs of Curaça in the Caribbean. More than half of these species have never been known to make sound.

Research results represent the most extensive collection of fish sounds ever published. The growing collection is available for everyone.

Researchers say that the identified sounds of the library can now be used to automatically train automatic learning systems to detect fish species in submarine records. This is similar to how birds can be identified via smartphones apps like Cornell Lab from Merlin d´Onithology. “We are far from being able to build” Merlin ‘for the oceans, but sounds are useful for scientists and environmentalists “, explains Dr. Aaron Rice, principal author of the study.

Dr. Dantzker adds: “By identifying the species that make sounds, allowing us to decode the sound landscapes of the reefs, transforming acoustic surveillance into a powerful tool for ocean conservation.”

Another technology force is that it can be placed in the reefs and left to collect data without the need for a diver or a boat to be present.

Dr. Rice, a main study of the study, said: “The fact that our recording system is issued in nature and can record for long periods means that we are able to capture the behaviors and sounds of the species that have never been observed before.”

Coral reefs are hot biodiversity hot spots. Shallow tropical coral reefs cover only 0.1% of the bottom of the ocean but support 25% of all marine species. However, they suffer from global drops caused by pressures, including climate change, unbearable pollution and fishing.

Their state in danger means that an effective monitoring of these ecosystems is more important than ever.

“These reefs decrease rapidly, threatening not only biodiversity, but also food security and livelihood of almost a billion people who depend on it,” said Dr. Dantzker. “In response, governments and NGOs invest billions in the protection and restoration of reefs.

Matt Duggan, a study author and a doctorate. The candidate working on the project, added: “So far, the noisiest species ”, such as dolphins, whales and shrimp, have overshadowed the many other voices of the sea. Discovering the identity of these hidden voices, acoustics will become a powerful indicator of health and resilience of the reefs and a strategy to monitor and deeply.

To create the tool – UPC360, researchers have combined spatial audio hydrophones (underwater microphones) with a 360 ° camera. This technique is used to create virtual reality video content, but has never been done underwater.

“Spatial audio allows you to hear the steering from which sounds are coming to the camera,” said Dr. Dantzker. “When we visualize this sound and put the image on the 360 ​​° image, the result is a video that can reveal what sound came from which fish.”

Although the results are the most extensive collection of these ever -published fish sounds, they always represent a fraction of total species in the reef. The researchers say that this technique opens the door to the decoding of the entire reef. They expand research, cultivate the Caribbean library and expand their efforts for other reefs from around the world, including Hawai’i and Indonesia, in the coming months.