Abstract:
Infrasonic noise has been found to be a dominant feature of the aquatic environment created by several types of tanks used extensively for farming fish [Clark et al., J. Acoust. Soc. Am. 99, 2558(A) (1996)]. Ground vibrations, pumps and other mechanical systems for cleaning, aerating and maintaining constant flows in the water can generate noise that is transmitted to the tanks by pipes, mounts, and airborne paths. Fluctuations in pressure and particle velocity can be further amplified by vibrations of the flexible tank walls. Fish can sense waterborne noise through both auditory and mechanosensory systems. When the noise occurs at high levels and for extended periods of time, the fish might not be able to adapt to its presence, and undesirable physiological effects such as lowered growth rate and hormone deficiencies could result. This talk describes an experimental study of physiological effects of infrasonic noise in the 5- to 20-Hz region on fingerlings grown in high densities in fiberglass tanks used for commercial fish farming. Comparisons are made with fish grown in tanks that have been acoustically quieted and in tanks where the noise levels are raised above the levels normally found in such facilities.