Grouper Calls – Research Answers

Florida Atlantic scientists have unlocked new insights into the calls of red hind groupers using more than 12 years of underwater audio recordings. These Caribbean fish travel more than 18 miles each winter to gather at offshore spawning sites under full moons. Males make two distinct low-frequency sounds — one to court females and another to defend territory.

To best track these sounds, researchers used passive acoustic monitoring to understand how they relate to behavior and population dynamics. Their discoveries revealed trends in their reproductive behavior – between 2011 and 2017 there was more frequent courtship calls but, in 2018 there was a shift to more competition and territorial calls.

“This shift could indicate changes in the population, such as an increase in the number of older or more dominant males, changes in sex ratios or even a shift in the core spawning area,” said Laurent Chérubin, Ph.D., lead author and a research professor at FAU Harbor Branch Oceanographic Institute.

Changes in the dynamics are especially important for managing the species, particularly during the vulnerable spawning season when overfishing can gravely impact the population.

“What’s remarkable is that even a single underwater microphone can reveal so much about fish populations,” Chérubin said. “With consistent long-term monitoring, we can pick up early warning signs – like shifts in spawning behavior or population stress – and give resource managers the information they need to adapt conservation strategies before it’s too late.”

Read the press release.