An investigation of the resonant behavior of the swimbladder for different species and sizes has been performed. Most measurements have been done using the ring-hydrophone method, but also a few normal echo measurements have been done. The results show the resonance frequency to increase with depth, but also to depend on what degree the fish is adapted to the depth. After a sudden transfer to new depth, the resonance frequency will first oscillate and then gradually adjust to a new resonance frequency given by the necessary swimbladder volume to retain neutral buoyancy. The time required to adapt to a deeper depth is longer than for a transfer in the opposite direction suggesting that gas production takes longer time than letting out gas. The observed Q values are also dependent on adaption, but appears to increase almost linearly with the resonance frequency at least for low Q values. The measured values are compared with a model for scattering from swimbladder fish and values for the swimbladder tension and viscosity of the fish tissue are calculated.
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vik et al. (1979) studied this question.