title: Sound characteristics of big-snout croaker, Johnius macrorhynus (Sciaenidae).
abstract: The sounds of a big-snout croaker, Johnius macrorhynus, produced under hand-held and voluntary conditions (in a large aquarium and in the field) were compared. Voluntary calls included "purr" and "dual-knocks", only purrs were produced when the fish was hand-held. The purr is composed of pulses in which the first interpulse interval was six to nine times longer than the other interpulse intervals, which were approximate in duration, and is a unique sound type in the coastal water of Taiwan. Purrs emitted under these conditions did not differ significantly, suggesting that the hand-held sound can be employed to match the sound in the field. These sounds contained energy reaching 5 kHz, with two peaks at about 1 and 2 kHz-the former being the dominant frequency. First interpulse interval, main interpulse interval, repetition rate of pulse, and pulse duration may serve as the diagnostic characters for the species-specific sound (i.e., purrs). One specimen survived in a large aquarium for 6 months and its vocal activity was monitored. The fish produced fewer dual-knocks than purrs, and purrs were about 11 dB louder than dual-knocks emitted in the aquarium. The temporal sequential relationship of these types in the sound of this individual was described.
authors.affiliation: Department of Environmental Biology and Fisheries Science, National Taiwan Ocean University, Keelung, Taiwan 202, ROC.
authors.forename: Yuan C
authors.initials: YC
authors.lastname: Lin
authors.forename: Hin K
authors.initials: HK
authors.lastname: Mok
authors.forename: Bao Q
authors.initials: BQ
authors.lastname: Huang
mesh_terms: D000162:Acoustics; D000818:Animals; D008297:Male; D023421:Models, Animal; D010473:Perciformes / Q000502:physiology*; D013045:Species Specificity; D014828:Vocalization, Animal / Q000502:physiology*