Red hind groupers are one of around 500 known hermaphroditic fish species. Instead of focusing on ambient sound levels, the marine biologists on this team were primarily interested in distinguishing mating calls. To do this, they used a machine-learning program called the Fish Acoustic Detection Algorithm Research (FADAR) system. “It’s a game changer for monitoring and managing reef fish like red hind.”Chérubin and colleagues discovered that male red hinds generally offer their neighbors one of two grunts. Beyond differentiating between the sounds, the team also confirmed consistent seasonal patterns in the grouper’s spawning activity that are closely linked to lunar cycles.