New Publication: Can passive acoustic monitoring replace plane-based aerial photography for quantifying human use of inland waters?

Published in the Journal of Environmental Management

Read the full article here ➜

We are pleased to announce the publication of a new article co-authored by Manuel Vieira from the Fish Bioacoustics Lab (MARE – Marine and Environmental Sciences Centre & ARNET – Aquatic Research Network, Faculty of Sciences, University of Lisbon), in collaboration with Théophile Turco, Marilyn Beauchaud, and Vincent Médoc from the ENES Bioacoustics Research Lab (CRNL, University of Saint-Étienne, CNRS, Inserm, France), Stéphan Jacquet and Jean Guillard from CARRTEL (INRAE, Université Savoie Mont Blanc, France), and Sébastien Cachera from the Comité Intercommunautaire pour l’Assainissement du Lac du Bourget (CISALB, France).

Large inland waters are focal points of human activity and play a critical role in maintaining ecosystem services. Effective management of these systems requires accurate quantification of human use, yet traditional approaches such as aerial photography or field observations are often resource-intensive, spatially constrained, and temporally limited.

This study evaluates whether underwater Passive Acoustic Monitoring (PAM) can serve as a reliable alternative to plane-based aerial photography (PAP) for monitoring boating activity on large freshwater bodies. To our knowledge, it is the first study to directly compare PAM with exhaustive traditional counts, providing new evidence on its reliability and applicability in underwater ecosystems.

Key Findings

• Strong correlations were observed between underwater sound levels and motorboat counts obtained from aerial surveys.

• The use of the one-third octave band centered at 1584 Hz slightly improved correlation strength compared to broadband sound pressure levels (0.01–20 kHz).

• Spectrogram-based visual analyses underestimated boat presence relative to aerial counts.

• Although PAM cannot provide exhaustive counts or high spatial resolution, it offers continuous, long-term, and cost-effective monitoring capabilities that complement or potentially substitute visual approaches.

  
  

Implications

The findings demonstrate that PAM can provide a robust and scalable method for assessing human use of freshwater ecosystems. By capturing acoustic signatures of boating activity, PAM can inform management decisions aimed at balancing recreation and conservation goals, particularly in large and multi-use lakes where conventional surveys are logistically challenging.

This research was conducted as part of the POLLUSON project (2020–2025), led by Vincent Médoc (ENES Bioacoustics Lab, Saint-Étienne) and funded by the Région Auvergne-Rhône-Alpes, which aims to assess anthropogenic noise in large freshwater ecosystems, particularly focusing on boating activity in Lake Bourget.

Reference: Turco, T., Vieira, M., Jacquet, S., Guillard, J., Cachera, S., Beauchaud, M., & Médoc, V. (2025). From sky to underwater: Can passive acoustic monitoring replace plane-based aerial photography for quantifying human use of inland waters? Journal of Environmental Management, 394, 127571. https://doi.org/10.1016/j.jenvman.2025.127571