Fishes produce different types of sounds including grunts, croaks, clicks, and snaps. Sounds may be produced as signals to predators or competitors, to attract mates, or as a fright response. Sounds are also unintentionally produced as a by-product of feeding or swimming. Ichthyologists may study fish sound production and/or usage . Scientists can listen to fish vocalizations, identify species, and document fish distribution patterns, especially those related to spawning (reproduction). These data provide valuable information to resource managers overseeing natural resource policies on the marine environment.
In addition to studying the sounds that fish produce, ichthyologists may use acoustics in their field research to study and track fish species. Fish finders detect the presence of fish primarily by detecting the air in their swim bladders. Sonar systems that are especially designed to locate fish, transmit sound pulses, measure the time it takes for echoes to return from an object (fish), and calculate the distance to that object. Acoustic fish tags are used to monitor and track fish movement. Each fish tag is a transmitter that produces a unique sound. By listening with a hydrophone, the location and depth of a tagged fish can be determined.
Ichthyologists may also study the potential effects on fish from anthropogenic (human-generated) sounds, such as those associated with airguns and pile driving . Potential effects of sound on fish may include: death, tissue damage, temporary hearing loss; behavioral changes; and increased stress. There is also the potential for these sounds to have no effect on fish.