From sounds to biodiversity management: fish bioacoustics for conservation
Fish are far from silent. Many species produce sounds that play key roles in behaviors such as courtship, spawning, and territorial defence, among others. These vocalisations are often, though not always, species-specific and contain biologically meaningful information embedded in their intra-sound features. Characteristics such as duration, number of pulses, and pulse period can reflect physiological states and reproductive activities. This widespread reliance on acoustic communication, estimated to occur in nearly two-thirds of ray-finned fish families, underpins the use of Passive Acoustic Monitoring (PAM) to detect and study fish populations and communities in diverse and often inaccessible marine environments. PAM has become a powerful tool for revealing species presence, diel and seasonal activity patterns, habitat use, spawning locations, and biodiversity trends across a range of spatial and temporal scales. Recent advances include the classification of fish sounds using dichotomous frameworks based on measurable acoustic features, enabling the application of ecological indices to assess community dynamics. These frameworks also likely provide a theoretical foundation for developing machine learning applications to monitor fish biodiversity through acoustics. Another key development is the integration of artificial intelligence for detecting and classifying specific fish sounds. The combination of AI, expert manual validation, and curated sound repositories has the potential to significantly enhance the accuracy, efficiency, and scalability of acoustic biodiversity assessments.
This chapter reviews current knowledge on the information embedded within fish sounds (intra-sound features), between fish sounds (rhythmic patterns), and across acoustic communities, with the aim of informing more effective AI development and marine conservation strategies. By tracing the evolution of fish acoustic research from foundational bioacoustics to ecoacoustic approaches, the chapter highlights how PAM can contribute to conservation and marine spatial planning. These efforts align with global conservation goals, such as those outlined in the United Nations Decade of Ocean Science for Sustainable Development, by promoting fishery-independent, scalable, and multidisciplinary monitoring frameworks.