Acoustic property of sound production by fat greenling (Hexagrammos otakii) in spawning season

Fat greenling (Hexagrammos otakii) is one of the important demersal fishes in Japanese local fisheries. Male fishes come over to neritic zone in spawning season, and make the territory as the spawning bed. It was suggested that fat greenling produces specific sounds during the protection of territory.The objective of this study was to examine acoustic properties of male sound production in spawning season as the basic data for estimating habitat density and activity by the passive acoustic methods. Field recordings were conducted during spawning season between Sept. and Nov. in 2014 and 2015. In each experiments, a specialized recorder was set by a territory throughout the breeding process, including courtship, spawning, and egg care. We extracted the acoustic properties such as the frequency of sound production, pulse duration, pulse number, call duration, and the frequency of sound production from recording data. There were different patterns of sound properties and their occurrence frequencies between before and after spawning. It was suggested that fat greenling changes the frequency and property of sound production depending on the situation like courtship, spawning, and protecting eggs.