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Acoustic Localization and Underwater Video
Off the coast of British Columbia, a team of biologists recorded more than a thousand acoustic signals emitted by eight species living on rocky reefs. Using a device that combines acoustic localization and underwater video, each sound could be precisely attributed to a specific species and behavior. The result: a true acoustic map of underwater interactions.
Some sounds are particularly distinctive. The black rockfish, for example, produces a low rumble similar to a frog?s croak, while the spiny rockfish emits a series of sharp clicks and grunts. These sounds vary depending on the situation being observed: fleeing from a predator, foraging, or territorial behavior. This diversity confirms that fish have a much richer repertoire of communication than previously thought.
A signature sound
Beyond behavior, the researchers also showed that these sounds vary depending on the individuals? morphology. Smaller fish emit higher-pitched frequencies than larger ones. By analyzing 47 acoustic parameters and incorporating them into a computer model, the team was able to identify species with 88% accuracy. This result supports the idea of a ?sonic signature? unique to each species.
These advances open up concrete possibilities for the management of marine environments. Acoustics now make it possible to detect the presence of a species without catching it, and even to estimate the size of individual fish. By increasing the number of recordings, it becomes possible to locate spawning grounds, track movements, or detect concentrations of fish, even in deep or hard-to-reach areas.
Discreet and noninvasive, this approach effectively complements traditional observation methods. Ultimately, it could make it possible to assess population abundance and better protect vulnerable species. In other words, listening to the sea could well become one of the key tools of modern marine conservation.
