Did you know that fish sing? Just like birds, they use sounds for courtship and other communication. This paper looks at best practices for using hydrophones and AI to monitor the choruses of aggregating grouper. The findings are a result of research conducted as part of the Grouper Moon Project, in collaboration with our partners at the Cayman Islands Department of Environment, Oregon State University, and NOAA.
The authors evaluated temporal and spatial trends in the detection of aggregation-associated sounds (AAS) made by Nassau Grouper (Epinephelus striatus) using an array of six hydrophones deployed across the large Nassau Grouper spawning aggregation on Little Cayman, Cayman Islands. The hydrophones collected continuous data for nine days during a winter spawning season. The team subsequently used an automatic classifier to extract the embedded Nassau Grouper sounds. Using the data in a sophisticated statistical model, the authors found variability in spatiotemporal detection rates. The findings of the study suggest hydrophone placement can strongly influence AAS detection rates. Given both the unpredicable movement and behavior of aggregating fish at spawning sites and the limits of AAS detection using standard monitoring tools, the authors suggest spawning site acoustic monitoring programs deploy hydrophone arrays of sufficient size to capture the site-wide trends in AAS rates.