Many fish produce sounds for courtship and mating, navigation, and defending their territories. Scientists analyze these sounds to study their behavior such as reproduction. Since grouper spawning is brief and it takes them a long time to reach sexual maturity, they are vulnerable to overfishing. ‘Eavesdropping’ on them is key to their survival. Researchers have developed a novel acoustic monitoring technique to classify grouper species by their sounds or ‘grouper calls,’ with accuracy of about 90 percent.