We don't usually think of fish as noisy animals, however, many species of fish are able to produce a variety of sounds, including clicks, purrs, grunts, pops, and even deeper noises like booms. A recent paper published in the The Journal of the Acoustical Society of America looked at the sounds made by different grouper species, as part of the Grouper Moon Project. Each winter, the Grouper Moon Project team visits Little Cayman in the Cayman Islands, to study the endangered Nassau Grouper spawning aggregation and better understand the ecology and dynamics of the aggregating grouper. During winter full moons, nearly 8,000 Nassau Grouper gather at the spawning site, and more than 20 other species of reef fish have been also documented using this important place for reproduction. This study used the sounds produced by Nassau Grouper, Red Hind, Black Grouper, and Yellowfin Grouper to monitor the positions of these fish at the aggregation.
By using fish sounds recorded by multiple instruments, we were able to monitor the presence and location of the fish before, during, and after Nassau Grouper spawning. By knowing the locations of the fish, it was possible to measure how loud these fish sounds are and determine how far away they may be detected. We found that Nassau Grouper sounds were the loudest and may be detectable up to 300 meters from the recording instruments! Additionally, the timing and locations of sound production suggest that there are no Nassau Grouper spawning events that occur during the night, but there may be overlap in space and time between Red Hind and Nassau Grouper spawning aggregations. These continuous and overnight sound recordings added valuable observations to the limited period of times when divers are able to survey the area, and adds to our understanding of this critical spawning aggregation.
The full citation of the paper is: Wilson, KC, A Širović, BX Semmens, SR Gittings, CV Pattengill-Semmens, and C McCoy. 2022. Grouper Source Levels and Aggregation Dynamics Inferred from Passive Acoustic Localization at a Multispecies Spawning Site. The Journal of the Acoustical Society of America. 151, 3052; https://doi.org/10.1121/10.0010236.
To see a full list of all scientific papers that have resulted from REEF's programs, visit www.REEF.org/db/publications.