Measurements of the Resonance Properties of Dummy Fish Swim Bladders

The resonant properties of fish swim bladders have been widely discussed and utilised in the application of marine biology like fish school localization, species classification and biomass estimation. Measurements and analysis of swim bladder resonance had been carried out mainly on saltwater species using the ring method and the ultrasound that required complicated experimental arrangements and conditions. For freshwater ecosystems, the application of resonant properties of fish swim bladders is not sufficiently established. Hence, a new method was developed for the purpose of measuring the resonance frequency and damping of fish swim bladders using an impedance tube. This tube was designed to be operated in the limit for frequencies below the lowest tube resonance, which was near 400 Hz. As a special form of bubbles in water, the acoustical properties of fish swim bladders can also be measured using the same method developed for measuring free bubbles and large encapsulated bubbles. Resonance frequencies and quality factors for dummy swim bladders of various sizes were measured for the purpose of simulating measurements on fish of various sizes.