Tim Stanton and colleagues have used broadband sound to identify fish of different sizes. Through a resonance classification technique that uses broadband sound to resonate fish swimbladders, fish of 2-5 cm length were observed to be collocated with predator species of 15-30 cm length. This observation, which could not otherwise be detected through conventional acoustics systems, led to new understanding of biological processes associated with the cost-benefit tradeoff in predator-prey relationships.
T.K. Stanton, C.J. Sellers, and J.M. Jech (2012). Resonance classification of mixed assemblages of fish with swimbladders using a modified commercial broadband acoustic echosounder at 1-6 kHz. Can. J. Fish. Aquat. Sci. 69: 854-868.